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Zhu S, Qin S, Wei C, Cen L, Xiong L, Luo X, Wang Y. Acetylcholine triggered enzymatic cascade reaction based on Fe 7S 8 nanoflakes catalysis for organophosphorus pesticides visual detection. Anal Chim Acta 2024; 1301:342464. [PMID: 38553122 DOI: 10.1016/j.aca.2024.342464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/08/2024] [Indexed: 04/02/2024]
Abstract
BACKGROUND Organophosphorus pesticides (OPs) play important roles in the natural environment, agricultural fields, and biological prevention. The development of OPs detection has gradually become an effective strategy to avoid the dangers of pesticides abuse and solve the severe environmental and health problems in humans. Although conventional assays for OPs analysis such as the bulky instrument required analytical methods have been well-developed, it still remains the limitation of inconvenient, inefficient and lab-dependence analysis in real samples. Hence, there is an urgent demand to develop efficient detection methods for OPs analysis in real scenarios. RESULTS Here, by virtue of the highly efficient catalytic performance in Fe7S8 nanoflakes (Fe7S8 NFs), we propose an OPs detection method that rationally integrated Fe7S8 NFs into the acetylcholine (ACh) triggered enzymatic cascade reaction (ATECR) for proceeding better detection performances. In this method, OPs serve as the enzyme inhibitors for inhibiting ATECR among ACh, acetylcholinesterase (AChE), and choline oxidase (CHO), then reduce the generation of H2O2 to suppress the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) that catalyzed by Fe7S8 NFs. Benefiting from the integration of Fe7S8 NFs and ATECR, it enables a sensitive detection for OPs (e.g. dimethoate). The proposed method has presented good linear ranges of OPs detection ranging from 0.1 to 10 μg mL-1. Compared to the other methods, the comparable limits of detection (LOD) of OPs are as low as 0.05 μg mL-1. SIGNIFICANCE Furthermore, the proposed method has also achieved a favorable visual detection performance of revealing OPs analysis in real samples. The visual signals of OPs can be transformed into RGB values and gathered by using smartphones, indicating the great potential in simple, sensitive, instrument-free and on-site analysis of pesticide residues in environmental monitoring and biosecurity research.
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Affiliation(s)
- Shu Zhu
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China
| | - Shangying Qin
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China
| | - Chonghui Wei
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China
| | - Li Cen
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China
| | - Luyun Xiong
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China
| | - Xingyu Luo
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China.
| | - Yilin Wang
- Guangxi Key Laboratory of Electrochemical Energy Materials, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, PR China.
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Yang Y, Arai T, Sasaki D, Kuramochi M, Inagaki H, Ohashi S, Sekiguchi H, Mio K, Kubo T, Sasaki YC. Real-time tilting and twisting motions of ligand-bound states of α7 nicotinic acetylcholine receptor. Eur Biophys J 2024; 53:15-25. [PMID: 38233601 PMCID: PMC10853312 DOI: 10.1007/s00249-023-01693-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/29/2023] [Accepted: 12/01/2023] [Indexed: 01/19/2024]
Abstract
The α7 nicotinic acetylcholine receptor is a member of the nicotinic acetylcholine receptor family and is composed of five α7 subunits arranged symmetrically around a central pore. It is localized in the central nervous system and immune cells and could be a target for treating Alzheimer's disease and schizophrenia. Acetylcholine is a ligand that opens the channel, although prolonged application rapidly decreases the response. Ivermectin was reported as one of the positive allosteric modulators, since the binding of Ivermectin to the channel enhances acetylcholine-evoked α7 currents. One research has suggested that tilting motions of the nicotinic acetylcholine receptor are responsible for channel opening and activation. To verify this hypothesis applies to α7 nicotinic acetylcholine receptor, we utilized a diffracted X-ray tracking method to monitor the stable twisting and tilting motion of nAChR α7 without a ligand, with acetylcholine, with Ivermectin, and with both of them. The results show that the α7 nicotinic acetylcholine receptor twists counterclockwise with the channel transiently opening, transitioning to a desensitized state in the presence of acetylcholine and clockwise without the channel opening in the presence of Ivermectin. We propose that the conformational transition of ACh-bound nAChR α7 may be due to the collective twisting of the five α7 subunits, resulting in the compression and movement, either downward or upward, of one or more subunits, thus manifesting tilting motions. These tilting motions possibly represent the transition from the resting state to channel opening and potentially to the desensitized state.
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Affiliation(s)
- Yue Yang
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
| | - Tatsuya Arai
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Daisuke Sasaki
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
| | - Masahiro Kuramochi
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- Graduate School of Science and Engineering, Ibaraki University, Hitachi, 316-8511, Japan
| | - Hidetoshi Inagaki
- Biomedical Research Insitute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan
| | - Sumiko Ohashi
- Biomedical Research Insitute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan
| | - Hiroshi Sekiguchi
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan
| | - Kazuhiro Mio
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Tai Kubo
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan
| | - Yuji C Sasaki
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8561, Japan.
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, 277-8565, Japan.
- Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.
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Li Z, Chan KC, Nickels JD, Cheng X. Electrostatic Contributions to the Binding Free Energy of Nicotine to the Acetylcholine Binding Protein. J Phys Chem B 2022; 126:8669-8679. [PMID: 36260486 PMCID: PMC10056799 DOI: 10.1021/acs.jpcb.2c04641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Biomolecular binding relies on specific attractive interactions between two partner molecules, including electrostatics, dispersion, hydrophobicity, and solvation. Assessing the contributions of electrostatic interactions to binding is key to the understanding of ligand binding mechanisms and the design of improved biomolecular binders. For example, nicotine is a well-known agonist of nicotinic acetylcholine receptors (nAChRs), but the molecular mechanisms for the differential action of nicotine on brain and muscle nAChRs remain elusive. In this work, we have chosen the acetylcholine binding protein (AChBP) in complex with nicotine as a model system to interrogate the electrostatic contributions to nicotine binding. Our absolute binding free energy simulations confirm that nicotine binds AChBP predominantly in its protonated (charged) form. By comparing energetic contributions from decomposed interactions for either neutral or charged nicotine, our calculations shed light on the nature of the binding of nicotine to the AChBP. The preferred binding of charged nicotine over neutral nicotine originates from its stronger electrostatic interactions with AChBP, a cation-π interaction to a tryptophan residue and a hydrogen bond between nicotine and the backbone carbonyl of the tryptophan, whereas the major force driving the binding process appears to be van der Waals interactions. The various nonelectrostatic terms can also indirectly modulate the electrostatic interactions through fine-tuning the binding pose of the ligand in the binding site, providing an explanation of why the binding specificity of nicotine to the brain versus muscle nAChRs is driven by electrostatic interaction, given that the immediate binding site residues, including the key tryptophan residue, are identical in the two receptors.
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Affiliation(s)
- Zoe Li
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio43210, United States
| | - Kevin C Chan
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio43210, United States
| | - Jonathan D Nickels
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio45221, United States
| | - Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy at The Ohio State University, Columbus, Ohio43210, United States
- Translational Data Analytics Institute (TDAI) at The Ohio State University, Columbus, Ohio43210, United States
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Luck VL, Richards DP, Shaikh AY, Franzyk H, Mellor IR. The Effects of Structural Alterations in the Polyamine and Amino Acid Moieties of Philanthotoxins on Nicotinic Acetylcholine Receptor Inhibition in the Locust, Schistocerca gregaria. Molecules 2021; 26:molecules26227007. [PMID: 34834099 PMCID: PMC8622278 DOI: 10.3390/molecules26227007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022] Open
Abstract
Alterations in the polyamine and amino acid (tyrosine) moieties of philanthotoxin-343 (PhTX-343) were investigated for their effects on the antagonism of nicotinic acetylcholine receptors (nAChRs) isolated from the locust (Schistocerca gregaria) mushroom body. Through whole-cell patch-clamp recordings, the philanthotoxin analogues in this study were shown to cause inhibition of the inward current when co-applied with acetylcholine (ACh). PhTX-343 (IC50 = 0.80 μM at -75 mV) antagonised locust nAChRs in a use-dependent manner, suggesting that it acts as an open-channel blocker. The analogue in which both the secondary amine functionalities were replaced with methylene groups (i.e., PhTX-12) was ~6-fold more potent (IC50 (half-maximal inhibitory concentration) = 0.13 μM at -75 mV) than PhTX-343. The analogue containing cyclohexylalanine as a substitute for the tyrosine moiety of PhTX-343 (i.e., Cha-PhTX-343) was also more potent (IC50 = 0.44 μM at -75 mV). A combination of both alterations to PhTX-343 generated the most potent analogue, i.e., Cha-PhTX-12 (IC50 = 1.71 nM at -75 mV). Modulation by PhTX-343 and Cha-PhTX-343 fell into two distinct groups, indicating the presence of two pharmacologically distinct nAChR groups in the locust mushroom body. In the first group, all concentrations of PhTX-343 and Cha-PhTX-343 inhibited responses to ACh. In the second group, application of PhTX-343 or Cha-PhTX-343 at concentrations ≤100 nM caused potentiation, while concentrations ≥ 1 μM inhibited responses to ACh. Cha-PhTX-12 may have potential to be developed into insecticidal compounds with a novel mode of action.
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Affiliation(s)
- Victoria L. Luck
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
| | - David P. Richards
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
| | - Ashif Y. Shaikh
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark; (A.Y.S.); (H.F.)
| | - Henrik Franzyk
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark; (A.Y.S.); (H.F.)
| | - Ian R. Mellor
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
- Correspondence: ; Tel.: +44-1159-513257
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Chen S, Renny MN, C. Tomé L, Olmedo‐Martínez JL, Udabe E, Jenkins EPW, Mecerreyes D, Malliaras GG, McLeod RR, Proctor CM. Reducing Passive Drug Diffusion from Electrophoretic Drug Delivery Devices through Co-Ion Engineering. Adv Sci (Weinh) 2021; 8:2003995. [PMID: 34194928 PMCID: PMC8224430 DOI: 10.1002/advs.202003995] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 02/17/2021] [Indexed: 05/13/2023]
Abstract
Implantable electrophoretic drug delivery devices have shown promise for applications ranging from treating pathologies such as epilepsy and cancer to regulating plant physiology. Upon applying a voltage, the devices electrophoretically transport charged drug molecules across an ion-conducting membrane out to the local implanted area. This solvent-flow-free "dry" delivery enables controlled drug release with minimal pressure increase at the outlet. However, a major challenge these devices face is limiting drug leakage in their idle state. Here, a method of reducing passive drug leakage through the choice of the drug co-ion is presented. By switching acetylcholine's associated co-ion from chloride to carboxylate co-ions as well as sulfopropyl acrylate-based polyanions, steady-state drug leakage rate is reduced up to sevenfold with minimal effect on the active drug delivery rate. Numerical simulations further illustrate the potential of this method and offer guidance for new material systems to suppress passive drug leakage in electrophoretic drug delivery devices.
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Affiliation(s)
- Shao‐Tuan Chen
- Electrical Engineering DivisionDepartment of EngineeringUniversity of CambridgeCambridgeCB3 0FAUK
| | - Megan N. Renny
- Materials Science and Engineering ProgramUniversity of ColoradoBoulderCO80309USA
| | - Liliana C. Tomé
- POLYMAT, University of the Basque Country UPV/EHUAvenida Tolosa 72Donostia‐San Sebastian20018Gipuzkoa, Spain
| | - Jorge L. Olmedo‐Martínez
- POLYMAT, University of the Basque Country UPV/EHUAvenida Tolosa 72Donostia‐San Sebastian20018Gipuzkoa, Spain
| | - Esther Udabe
- POLYMAT, University of the Basque Country UPV/EHUAvenida Tolosa 72Donostia‐San Sebastian20018Gipuzkoa, Spain
| | - Elise P. W. Jenkins
- Electrical Engineering DivisionDepartment of EngineeringUniversity of CambridgeCambridgeCB3 0FAUK
| | - David Mecerreyes
- POLYMAT, University of the Basque Country UPV/EHUAvenida Tolosa 72Donostia‐San Sebastian20018Gipuzkoa, Spain
- IkerbasqueBasque Foundation for ScienceBilbao48013Spain
| | - George G. Malliaras
- Electrical Engineering DivisionDepartment of EngineeringUniversity of CambridgeCambridgeCB3 0FAUK
| | - Robert R. McLeod
- Materials Science and Engineering ProgramUniversity of ColoradoBoulderCO80309USA
- Department of Electrical, Computer & Energy EngineeringUniversity of ColoradoBoulderCO80309USA
| | - Christopher M. Proctor
- Electrical Engineering DivisionDepartment of EngineeringUniversity of CambridgeCambridgeCB3 0FAUK
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Prevost MS, Bouchenaki H, Barilone N, Gielen M, Corringer PJ. Concatemers to re-investigate the role of α5 in α4β2 nicotinic receptors. Cell Mol Life Sci 2021; 78:1051-1064. [PMID: 32472188 PMCID: PMC11071962 DOI: 10.1007/s00018-020-03558-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 05/15/2020] [Accepted: 05/22/2020] [Indexed: 01/08/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ion channels expressed in the central nervous systems. nAChRs containing the α4, β2 and α5 subunits are specifically involved in addictive processes, but their functional architecture is poorly understood due to the intricacy of assembly of these subunits. Here we constrained the subunit assembly by designing fully concatenated human α4β2 and α4β2α5 receptors and characterized their properties by two-electrodes voltage-clamp electrophysiology in Xenopus oocytes. We found that α5-containing nAChRs are irreversibly blocked by methanethiosulfonate (MTS) reagents through a covalent reaction with a cysteine present only in α5. MTS-block experiments establish that the concatemers are expressed in intact form at the oocyte surface, but that reconstitution of nAChRs from loose subunits show inefficient and highly variable assembly of α5 with α4 and β2. Mutational analysis shows that the concatemers assemble both in clockwise and anticlockwise orientations, and that α5 does not contribute to ACh binding from its principal (+) site. Reinvestigation of suspected α5-ligands such as galantamine show no specific effect on α5-containing concatemers. Analysis of the α5-D398N mutation that is linked to smoking and lung cancer shows no significant effect on the electrophysiological function, suggesting that its effect might arise from alteration of other cellular processes. The concatemeric strategy provides a well-characterized platform for mechanistic analysis and screening of human α5-specific ligands.
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Affiliation(s)
- Marie S Prevost
- Unité Récepteurs-Canaux, Institut Pasteur, UMR 3571, CNRS, 75015, Paris, France
| | - Hichem Bouchenaki
- Unité Récepteurs-Canaux, Institut Pasteur, UMR 3571, CNRS, 75015, Paris, France
| | - Nathalie Barilone
- Unité Récepteurs-Canaux, Institut Pasteur, UMR 3571, CNRS, 75015, Paris, France
| | - Marc Gielen
- Unité Récepteurs-Canaux, Institut Pasteur, UMR 3571, CNRS, 75015, Paris, France.
- Sorbonne Université, 21, rue de l'école de médecine, 75006, Paris, France.
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Affiliation(s)
- Victor I Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
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8
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Pochini L, Pappacoda G, Galluccio M, Pastore F, Scalise M, Indiveri C. Effect of Cholesterol on the Organic Cation Transporter OCTN1 (SLC22A4). Int J Mol Sci 2020; 21:ijms21031091. [PMID: 32041338 PMCID: PMC7037232 DOI: 10.3390/ijms21031091] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/02/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023] Open
Abstract
The effect of cholesterol was investigated on the OCTN1 transport activity measured as [14C]-tetraethylamonium or [3H]-acetylcholine uptake in proteoliposomes reconstituted with native transporter extracted from HeLa cells or the human recombinant OCTN1 over-expressed in E. coli. Removal of cholesterol from the native transporter by MβCD before reconstitution led to impairment of transport activity. A similar activity impairment was observed after treatment of proteoliposomes harboring the recombinant (cholesterol-free) protein by MβCD, suggesting that the lipid mixture used for reconstitution contained some cholesterol. An enzymatic assay revealed the presence of 10 µg cholesterol/mg total lipids corresponding to 1% cholesterol in the phospholipid mixture used for the proteoliposome preparation. On the other way around, the activity of the recombinant OCTN1 was stimulated by adding the cholesterol analogue, CHS to the proteoliposome preparation. Optimal transport activity was detected in the presence of 83 µg CHS/ mg total lipids for both [14C]-tetraethylamonium or [3H]-acetylcholine uptake. Kinetic analysis of transport demonstrated that the stimulation of transport activity by CHS consisted in an increase of the Vmax of transport with no changes of the Km. Altogether, the data suggests a direct interaction of cholesterol with the protein. A further support to this interpretation was given by a docking analysis indicating the interaction of cholesterol with some protein sites corresponding to CARC-CRAC motifs. The observed direct interaction of cholesterol with OCTN1 points to a possible direct influence of cholesterol on tumor cells or on acetylcholine transport in neuronal and non-neuronal cells via OCTN1.
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Fadilla RN, Rusydi F, Aisyah ND, Khoirunisa V, Dipojono HK, Ahmad F, Mudasir M, Puspitasari I. A Density-Functional Study of the Conformational Preference of Acetylcholine in the Neutral Hydrolysis. Molecules 2020; 25:E670. [PMID: 32033277 PMCID: PMC7037165 DOI: 10.3390/molecules25030670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 01/24/2020] [Accepted: 01/29/2020] [Indexed: 12/17/2022] Open
Abstract
Acetylcholine, which is associated with Alzheimer's disease, is widely known to have conformers. The preference of each conformer to undergo neutral hydrolysis is yet to be considered. In this study, we employed density-functional calculations to build the conformers and investigated their preference in one-step neutral hydrolysis. The results showed the preference in ten possible hydrolysis pathways involving seven acetylcholine conformers (reactant), four transition state structures, and two choline conformers (product). Three out of the seven acetylcholine conformers predicted from the results confirmed experimental findings on the conformers stability. We suggested that two out of ten possible pathways were observed in the experimental results based on agreement in reaction energy. Eventually, this study will emphasize the importance of considering acetylcholine conformers in its hydrolysis study.
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Affiliation(s)
- Rizka N. Fadilla
- Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia; (R.N.F.); (N.D.A.); (V.K.); (I.P.)
- Department of Engineering Physics, Faculty of Industrial Engineering, Institut Teknologi Bandung, Bandung 40132, Indonesia;
| | - Febdian Rusydi
- Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia; (R.N.F.); (N.D.A.); (V.K.); (I.P.)
- Department of Physics, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia
- Precision Sciences & Technology and Applied Physics, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan
| | - Nufida D. Aisyah
- Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia; (R.N.F.); (N.D.A.); (V.K.); (I.P.)
- Department of Engineering Physics, Faculty of Industrial Engineering, Institut Teknologi Bandung, Bandung 40132, Indonesia;
| | - Vera Khoirunisa
- Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia; (R.N.F.); (N.D.A.); (V.K.); (I.P.)
- Department of Engineering Physics, Faculty of Industrial Engineering, Institut Teknologi Bandung, Bandung 40132, Indonesia;
- Engineering Physics Study Program, Institut Teknologi Sumatera, Jl. Terusan Ryacudu, Lampung Selatan 35365, Indonesia
| | - Hermawan K. Dipojono
- Department of Engineering Physics, Faculty of Industrial Engineering, Institut Teknologi Bandung, Bandung 40132, Indonesia;
| | - Faozan Ahmad
- Department of Physics, Faculty of Mathematics and Science, Institut Pertanian Bogor, Bogor 16680, Indonesia;
| | - Mudasir Mudasir
- Department of Chemistry, Faculty of Mathematics and Science, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia;
| | - Ira Puspitasari
- Research Center for Quantum Engineering Design, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia; (R.N.F.); (N.D.A.); (V.K.); (I.P.)
- Information System Study Program, Faculty of Science and Technology, Universitas Airlangga, Jl. Mulyorejo, Surabaya 60115, Indonesia
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Lauer JC, Pang Z, Janßen P, Rominger F, Kirschbaum T, Elstner M, Mastalerz M. Host-Guest Chemistry of Truncated Tetrahedral Imine Cages with Ammonium Ions. ChemistryOpen 2020; 9:183-190. [PMID: 32025463 PMCID: PMC6996569 DOI: 10.1002/open.201900357] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/10/2020] [Indexed: 01/29/2023] Open
Abstract
Three shape-persistent [4+4] imine cages with truncated tetrahedral geometry with different window sizes were studied as hosts for the encapsulation of tetra-n-alkylammonium salts of various bulkiness. In various solvents the cages behave differently. For instance, in dichloromethane the cage with smallest window size takes up NEt4+ but not NMe4+, which is in contrast to the two cages with larger windows hosting both ions. To find out the reason for this, kinetic experiments were carried out to determine the velocity of uptake but also to deduce the activation barriers for these processes. To support the experimental results, calculations for the guest uptakes have been performed by molecular mechanics' simulations. Finally, the complexation of pharmaceutical interested compounds, such as acetylcholine, muscarine or denatonium have been determined by NMR experiments.
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Affiliation(s)
- Jochen C. Lauer
- Organisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Ziwei Pang
- Institut für Physikalische Chemie Theoretische Chemische BiologieUniversität Karlsruhe Geb. 30.44Kaiserstr. 1276131KarlsruheGermany
| | - Paul Janßen
- Organisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Frank Rominger
- Organisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Tobias Kirschbaum
- Organisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Marcus Elstner
- Institut für Physikalische Chemie Theoretische Chemische BiologieUniversität Karlsruhe Geb. 30.44Kaiserstr. 1276131KarlsruheGermany
| | - Michael Mastalerz
- Organisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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Cho DH. Telmisartan Inhibits Nitric Oxide Production and Vessel Relaxation via Protein Phosphatase 2A-mediated Endothelial NO Synthase-Ser 1179 Dephosphorylation. J Korean Med Sci 2019; 34:e266. [PMID: 31674157 PMCID: PMC6823522 DOI: 10.3346/jkms.2019.34.e266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Apart from its blood pressure-lowering effect by blocking the renin-angiotensin-aldosterone system, telmisartan, an angiotensin II type 1 receptor blocker (ARB), exhibits various ancillary effects including cardiovascular protective effects in vitro. Nonetheless, the protective effects of telmisartan in cerebrocardiovascular diseases are somewhat variable in large-scale clinical trials. Dysregulation of endothelial nitric oxide (NO) synthase (eNOS)-derived NO contributes to the developments of various vascular diseases. Nevertheless, the direct effects of telmisartan on endothelial functions including NO production and vessel relaxation, and its action mechanism have not been fully elucidated. Here, we investigated the mechanism by which telmisartan regulates NO production and vessel relaxation in vitro and in vivo. METHODS We measured nitrite levels in culture medium and mouse serum, and performed inhibitor studies and western blot analyses using bovine aortic endothelial cells (BAECs) and a hyperglycemic mouse model. To assess vessel reactivity, we performed acetylcholine (ACh)-induced vessel relaxation assay on isolated rat aortas. RESULTS Telmisartan decreased NO production in normoglycemic and hyperglycemic BAECs, which was accompanied by reduced phosphorylation of eNOS at Ser1179 (p-eNOS-Ser1179). Telmisartan increased the expression of protein phosphatase 2A catalytic subunit (PP2Ac) and co-treatment with okadaic acid completely restored telmisartan-inhibited NO production and p-eNOS-Ser1179 levels. Of the ARBs tested (including losartan and fimasartan), only telmisartan decreased NO production and p-eNOS-Ser1179 levels, and enhanced PP2Ac expression. Co-treatment with GW9662 had no effect on telmisartan-induced changes. In line with in vitro observations, telmisartan reduced serum nitrite and p-eNOS-Ser1179 levels, and increased PP2Ac expression in high fat diet-fed mice. Furthermore, telmisartan attenuated ACh-induced rat aorta relaxation. CONCLUSION We demonstrated that telmisartan inhibited NO production and vessel relaxation at least in part by PP2A-mediated eNOS-Ser1179 dephosphorylation in a peroxisome proliferator-activated receptor γ-independent manner. These results may provide a mechanism that explains the inconsistent cerebrocardiovascular protective effects of telmisartan.
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Affiliation(s)
- Du Hyong Cho
- Department of Pharmacology, Yeungnam University College of Medicine, Daegu, Korea.
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12
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González-Gutiérrez JP, Pessoa-Mahana HA, Iturriaga-Vásquez PE, Reyes-Parada MI, Guerra-Díaz NE, Hodar-Salazar M, Viscarra F, Paillali P, Núñez-Vivanco G, Lorca-Carvajal MA, Mella-Raipán J, Zúñiga MC. Synthesis of Novel Nicotinic Ligands with Multimodal Action: Targeting Acetylcholine α4β2, Dopamine and Serotonin Transporters. Molecules 2019; 24:molecules24203808. [PMID: 31652614 PMCID: PMC6832503 DOI: 10.3390/molecules24203808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/07/2019] [Accepted: 10/20/2019] [Indexed: 11/16/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs), serotonin transporters (SERT) and dopamine transporters (DAT) represent targets for the development of novel nicotinic derivatives acting as multiligands associated with different health conditions, such as depressive, anxiety and addiction disorders. In the present work, a series of functionalized esters structurally related to acetylcholine and nicotine were synthesized and pharmacologically assayed with respect to these targets. The synthesized compounds were studied in radioligand binding assays at α4β2 nAChR, h-SERT and h-DAT. SERT experiments showed not radioligand [3H]-paroxetine displacement, but rather an increase in the radioligand binding percentage at the central binding site was observed. Compound 20 showed Ki values of 1.008 ± 0.230 μM for h-DAT and 0.031 ± 0.006 μM for α4β2 nAChR, and [3H]-paroxetine binding of 191.50% in h-SERT displacement studies, being the only compound displaying triple affinity. Compound 21 displayed Ki values of 0.113 ± 0.037 μM for α4β2 nAChR and 0.075 ± 0.009 μM for h-DAT acting as a dual ligand. Molecular docking studies on homology models of α4β2 nAChR, h-DAT and h-SERT suggested potential interactions among the compounds and agonist binding site at the α4/β2 subunit interfaces of α4β2 nAChR, central binding site of h-DAT and allosteric modulator effect in h-SERT.
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Affiliation(s)
- Juan Pablo González-Gutiérrez
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 8380492 Santiago, Chile.
| | - Hernán Armando Pessoa-Mahana
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 8380492 Santiago, Chile.
| | - Patricio Ernesto Iturriaga-Vásquez
- Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, 4811230 Temuco, Chile.
- Center of Excellence in Biotechnology Research Applied to the Environment, Universidad de La Frontera, 4811230 Temuco, Chile.
| | - Miguel Iván Reyes-Parada
- Centro de Investigación Biomédica y Aplicada (CIBAP), Escuela de Medicina, Facultad de Ciencias Médicas, Universidad de Santiago de Chile, 9170022 Santiago, Chile.
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, 3467987 Sede Talca, Chile.
| | - Nicolas Esteban Guerra-Díaz
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 8380492 Santiago, Chile.
| | - Martin Hodar-Salazar
- Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, 4811230 Temuco, Chile.
| | - Franco Viscarra
- Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, 4811230 Temuco, Chile.
| | - Pablo Paillali
- Departamento de Ciencias Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, Universidad de la Frontera, 4811230 Temuco, Chile.
| | - Gabriel Núñez-Vivanco
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, 3340000 Talca, Chile.
- Escuela de Ingeniería Civil en Bioinformática, Universidad de Talca, Av. Lircay 3340000 Talca, Chile.
| | | | - Jaime Mella-Raipán
- Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, 2360102 Valparaíso, Chile.
| | - María Carolina Zúñiga
- Departamento de Química Inorgánica and Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 8380492 Santiago, Chile.
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13
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Tanaka Y, Funano SI, Noguchi Y, Yalikun Y, Kamamichi N. A valve powered by earthworm muscle with both electrical and 100% chemical control. Sci Rep 2019; 9:8042. [PMID: 31285453 PMCID: PMC6614428 DOI: 10.1038/s41598-019-44116-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 05/07/2019] [Indexed: 01/09/2023] Open
Abstract
Development of bio-microactuators combining microdevices and cellular mechanical functions has been an active research field owing to their desirable properties including high mechanical integrity and biocompatibility. Although various types of devices were reported, the use of as-is natural muscle tissue should be more effective. An earthworm muscle-driven valve has been created. Long-time (more than 2 min) and repeatable displacement was observed by chemical (acetylcholine) stimulation. The generated force of the muscle (1 cm × 3 cm) was 1.57 mN on average for 2 min by the acetylcholine solution (100 mM) stimulation. We demonstrated an on-chip valve that stopped the constant pressure flow by the muscle contraction. For electrical control, short pulse stimulation was used for the continuous and repeatable muscle contraction. The response time was 3 s, and the pressure resistance was 3.0 kPa. Chemical stimulation was then used for continuous muscle contraction. The response time was 42 s, and the pressure resistance was 1.5 kPa. The ON (closed) state was kept for at least 2 min. An on-chip valve was demonstrated that stopped the constant pressure flow by the muscle contraction. This is the first demonstration of the muscle-based valve that is 100% chemically actuated and controlled.
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Affiliation(s)
- Yo Tanaka
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Shun-Ichi Funano
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuji Noguchi
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Department of Robotics and Mechatronics, Tokyo Denki University, 5 Senju-asahi-cho, Adachi-ku, Tokyo, 120-8551, Japan
| | - Yaxiaer Yalikun
- Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Norihiro Kamamichi
- Department of Robotics and Mechatronics, Tokyo Denki University, 5 Senju-asahi-cho, Adachi-ku, Tokyo, 120-8551, Japan
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Weltzin MM, George AA, Lukas RJ, Whiteaker P. Distinctive single-channel properties of α4β2-nicotinic acetylcholine receptor isoforms. PLoS One 2019; 14:e0213143. [PMID: 30845161 PMCID: PMC6405073 DOI: 10.1371/journal.pone.0213143] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/17/2019] [Indexed: 11/19/2022] Open
Abstract
Central nervous system nicotinic acetylcholine receptors (nAChR) are predominantly of the α4β2 subtype. Two isoforms exist, with high or low agonist sensitivity (HS-(α4β2)2β2- and LS-(α4β2)2α4-nAChR). Both isoforms exhibit similar macroscopic potency and efficacy values at low acetylcholine (ACh) concentrations, mediated by a common pair of high-affinity α4(+)/(-)β2 subunit binding interfaces. However LS-(α4β2)2α4-nAChR also respond to higher concentrations of ACh, acting at a third α4(+)/(-)α4 subunit interface. To probe isoform functional differences further, HS- and LS-α4β2-nAChR were expressed in Xenopus laevis oocytes and single-channel responses were assessed using cell-attached patch-clamp. In the presence of a low ACh concentration, both isoforms produce low-bursting function. HS-(α4β2)2β2-nAChR exhibit a single conductance state, whereas LS-(α4β2)2α4-nAChR display two distinctive conductance states. A higher ACh concentration did not preferentially recruit either conductance state, but did result in increased LS-(α4β2)2α4-nAChR bursting and reduced closed times. Introduction of an α4(+)/(-)α4-interface loss-of-function α4W182A mutation abolished these changes, confirming this site's role in mediating LS-(α4β2)2α4-nAChR responses. Small or large amplitude openings are highly-correlated within individual LS-(α4β2)2α4-nAChR bursts, suggesting that they arise from distinct intermediate states, each of which is stabilized by α4(+)/(-)α4 site ACh binding. These findings are consistent with α4(+)/(-)α4 subunit interface occupation resulting in allosteric potentiation of agonist actions at α4(+)/(-)β2 subunit interfaces, rather than independent induction of high conductance channel openings.
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Affiliation(s)
- Maegan M. Weltzin
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
- * E-mail:
| | - Andrew A. George
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
| | - Ronald J. Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, United States of America
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15
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Hoppe A, Marti-Solano M, Drabek M, Bünemann M, Kolb P, Rinne A. The allosteric site regulates the voltage sensitivity of muscarinic receptors. Cell Signal 2017; 42:114-126. [PMID: 29056499 DOI: 10.1016/j.cellsig.2017.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 09/28/2017] [Accepted: 10/19/2017] [Indexed: 11/18/2022]
Abstract
Muscarinic receptors (M-Rs) for acetylcholine (ACh) belong to the class A of G protein-coupled receptors. M-Rs are activated by orthosteric agonists that bind to a specific site buried in the M-R transmembrane helix bundle. In the active conformation, receptor function can be modulated either by allosteric modulators, which bind to the extracellular receptor surface or by the membrane potential via an unknown mechanism. Here, we compared the modulation of M1-Rs and M3-Rs induced by changes in voltage to their allosteric modulation by chemical compounds. We quantified changes in receptor signaling in single HEK 293 cells with a FRET biosensor for the Gq protein cycle. In the presence of ACh, M1-R signaling was potentiated by voltage, similarly to positive allosteric modulation by benzyl quinolone carboxylic acid. Conversely, signaling of M3-R was attenuated by voltage or the negative allosteric modulator gallamine. Because the orthosteric site is highly conserved among M-Rs, but allosteric sites vary, we constructed "allosteric site" M3/M1-R chimeras and analyzed their voltage dependencies. Exchanging the entire allosteric sites eliminated the voltage sensitivity of ACh responses for both receptors, but did not affect their modulation by allosteric compounds. Furthermore, a point mutation in M3-Rs caused functional uncoupling of the allosteric and orthosteric sites and abolished voltage dependence. Molecular dynamics simulations of the receptor variants indicated a subtype-specific crosstalk between both sites, involving the conserved tyrosine lid structure of the orthosteric site. This molecular crosstalk leads to receptor subtype-specific voltage effects.
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Affiliation(s)
- Anika Hoppe
- Department of Cardiovascular Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44780 Bochum, Germany
| | - Maria Marti-Solano
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Matthäus Drabek
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Moritz Bünemann
- Department of Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marbacher Weg 6-10, 35032 Marburg, Germany
| | - Andreas Rinne
- Department of Cardiovascular Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
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16
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Mal K, Abhishekh HA, Chawla MP, Raju TR, Sathyaprabha TN. Influence of age and gender on the function of postganglionic sympathetic sudomotor axons. Natl Med J India 2017; 30:136-138. [PMID: 28936997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
BACKGROUND The quantitative sudomotor axon reflex test (QSART) is an autonomic function test to evaluate the function of postganglionic sympathetic sudomotor axons. The QSART is used for research and in clinical assessment of various neurological diseases, but few studies have assessed the influence of age, gender and reported a normative range. We assessed the influence of age and gender on QSART parameters. METHODS We recruited 61 healthy volunteers (41 men and 20 women) after obtaining written informed consent. The QSART was recorded as per standard protocol after iontophoretic stimulation (using acetylcholine) for 5 minutes. We analysed the sweat response to obtain total sweat production, rate of sweat production and latency time from the start of stimulation to sweat response. We assessed these parameters in the right medial forearm, right proximal leg, right distal leg and right proximal foot. RESULTS Men had significantly higher evoked sweat volume and sweat latency period compared to women. A positive correlation was observed between age and evoked total sweat volume. An inverse correlation was noted between age and evoked sweat latency period. CONCLUSION Postganglionic sudomotor function increased significantly with age. Men had significantly higher sweat volume suggesting sympathetic predominance. These results might help establish normative data for the Indian population.
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Affiliation(s)
- Kedar Mal
- Centre for Converging Technologies, University of Rajasthan, Jaipur, Rajasthan, India
| | - Hulegar A Abhishekh
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Hosur Road, Bengaluru 560029, Karnataka, India
| | - Mahavir Prasad Chawla
- Centre for Converging Technologies, University of Rajasthan, Jaipur, Rajasthan, India
| | - Trichur R Raju
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Hosur Road, Bengaluru 560029, Karnataka, India
| | - Talakad N Sathyaprabha
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Hosur Road, Bengaluru 560029, Karnataka, India
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Kjær C, Stockett MH, Pedersen BM, Nielsen SB. Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments. J Phys Chem B 2016; 120:12105-12110. [PMID: 27933942 DOI: 10.1021/acs.jpcb.6b10547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here, on the basis of photodissociation action spectroscopy, we establish that the redshift of the Soret absorption band due to binding of a negatively charged carboxylate (as present in aspartic acid and glutamic acid residues) is 0.1-0.2 eV for Chl a and b. This effect is almost enough to reproduce the well-known green color of plants and can account for the strong spectral variation between Chl's. The experimental data serve to benchmark future high-level calculations of excited-state energies. Finally, we demonstrate that complexes between Chl a and histidine, tagged by a quaternary ammonium ion, can be made in the gas phase by electrospray ionization, but more work is needed to produce enough ions for gas-phase spectroscopy.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Mark H Stockett
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Bjarke M Pedersen
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
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Wang YH, Kumarihamy M, Wang M, Smesler A, Khan IA, León F, Cutler SJ, Muhammad I. Quantitative Determination of Betaine, Choline, Acetylcholine, and 20-Hydroxyecdysone Simultaneously from Atriplex Species by UHPLC-UV-MS. Nat Prod Commun 2016; 11:1689-1692. [PMID: 30475508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023] Open
Abstract
A simple, rapid, and sensitive UHPLC-UV-MS method was developed for the quantitative determination of betaine (1), choline (2), acetylcholine (3), and 20-hydroxyecdysone (4) from various species of Atriplex. The baseline separation of the four analytes was achieved on a reversed phase C 18 column within nine minutes. The mobile phase was composed of 50 mM ammonium formate in 2% methanol-water containing 5 mM sodium dodecyl sulfate (pH = 8.2) and methanol with 0.01% ammonium hydroxide. The analytical method was validated for recovery, precision, limits of detection (LOD), and limits of quantification (LOQ). The developed method was applied for the characterization and quantitation of analytes from plant parts of different Atriplex species, including A. canescens, A. fruticulosa, A. fasciculata, A. semibaccata, and A. lentiformis. Compounds 1-4 were found in a range of 0.53-1.61%, detection under limit of quantification (DUL)-0.74, DUL-0.0038, and 0-0.10% (w/w, mg in 100 mg plant material), respectively, in test samples. In leaf and fruit of A. canescens, a high content of 1, 2, and 4 were identified. The content of 1, 2, and 4 in A. canescens explains the potential implications of this native US plant for human health and nutrition. The result of this study provides a new method to analyze these phytoconstituents simultaneously in a mixture.
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Wang S, Jeffries E, Gao J, Sun L, You Z, Wang Y. Polyester with Pendent Acetylcholine-Mimicking Functionalities Promotes Neurite Growth. ACS Appl Mater Interfaces 2016; 8:9590-9599. [PMID: 27010971 DOI: 10.1021/acsami.5b12379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Successful regeneration of nerves can benefit from biomaterials that provide a supportive biochemical and mechanical environment while also degrading with controlled inflammation and minimal scar formation. Herein, we report a neuroactive polymer functionalized by covalent attachment of the neurotransmitter acetylcholine (Ach). The polymer was readily synthesized in two steps from poly(sebacoyl diglyceride) (PSeD), which previously demonstrated biocompatibility and biodegradation in vivo. Distinct from prior acetylcholine-biomimetic polymers, PSeD-Ach contains both quaternary ammonium and free acetyl moieties, closely resembling native acetylcholine structure. The polymer structure was confirmed via (1)H nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Hydrophilicity, charge, and thermal properties of PSeD-Ach were determined by tensiometer, zetasizer, differential scanning calorimetry, and thermal gravimetric analysis, respectively. PC12 cells exhibited the greatest proliferation and neurite outgrowth on PSeD-Ach and laminin substrates, with no significant difference between these groups. PSeD-Ach yielded much longer neurite outgrowth than the control polymer containing ammonium but no the acetyl group, confirming the importance of the entire acetylcholine-like moiety. Furthermore, PSeD-Ach supports adhesion of primary rat dorsal root ganglions and subsequent neurite sprouting and extension. The sprouting rate is comparable to the best conditions from previous report. Our findings are significant in that they were obtained with acetylcholine-like functionalities in 100% repeating units, a condition shown to yield significant toxicity in prior publications. Moreover, PSeD-Ach exhibited favorable mechanical and degradation properties for nerve tissue engineering application. Humidified PSeD-Ach had an elastic modulus of 76.9 kPa, close to native neural tissue, and could well recover from cyclic dynamic compression. PSeD-Ach showed a gradual in vitro degradation under physiologic conditions with a mass loss of 60% within 4 weeks. Overall, this simple and versatile synthesis provides a useful tool to produce biomaterials for creating the appropriate stimulatory environment for nerve regeneration.
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Affiliation(s)
- Shaofei Wang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University , 2999 North Renmin Road, Shanghai 201620, P. R. China
| | - Eric Jeffries
- Departments of Bioengineering, Chemical Engineering, Surgery, and the McGowan Institute, University of Pittsburgh , 3700 O'Hara Street, Pittsburgh, Pennsylvania 15261, United States
| | - Jin Gao
- Departments of Bioengineering, Chemical Engineering, Surgery, and the McGowan Institute, University of Pittsburgh , 3700 O'Hara Street, Pittsburgh, Pennsylvania 15261, United States
| | - Lijie Sun
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University , 2999 North Renmin Road, Shanghai 201620, P. R. China
| | - Zhengwei You
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University , 2999 North Renmin Road, Shanghai 201620, P. R. China
| | - Yadong Wang
- Departments of Bioengineering, Chemical Engineering, Surgery, and the McGowan Institute, University of Pittsburgh , 3700 O'Hara Street, Pittsburgh, Pennsylvania 15261, United States
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20
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Bayri A, Unal S, Altin S, Bulut F, Dayanc BE. Altered isotope charge distribution of acetylcholine neurotransmitter and Myasthenia Gravis. Med Hypotheses 2016; 89:84-8. [PMID: 26968916 DOI: 10.1016/j.mehy.2016.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/25/2016] [Accepted: 01/29/2016] [Indexed: 11/30/2022]
Abstract
Acetylcholine (ACh) is a central neurotransmitter that is used for signal transmission among neurons. For signal transmission in neurons, a neurotransmitter must bind to its receptor in order to produce an action potential. It is known that in Myasthenia Gravis (MG) cases, autoantibodies could block this binding. In the future, the treatment of MG could be achieved via modulation of molecular interaction between ACh and acetylcholine receptor (AChR). This study suggests that if an atom on a ligand (i.e. a neurotransmitter) is replaced with its isotope, it may cause charge redistribution such as that the binding between ligand and its receptor may be improved. Hence suggesting that with replacement of atoms with their isotopes in any biologically important ligand could alter its affinity towards its corresponding receptor, which would have a wide array of applications in medicine.
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Affiliation(s)
- A Bayri
- Inonu University, Physics Department, 44280 Malatya, Turkey
| | - S Unal
- Inonu University, Psychiatry Department, 44280 Malatya, Turkey
| | - S Altin
- Inonu University, Physics Department, 44280 Malatya, Turkey
| | - F Bulut
- Inonu University, Physics Department, 44280 Malatya, Turkey
| | - B E Dayanc
- Inonu University, Department of Molecular Biology and Genetics, 44280 Malatya, Turkey
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Fillafer C, Schneider MF. On the excitation of action potentials by protons and its potential implications for cholinergic transmission. Protoplasma 2016; 253:357-365. [PMID: 25874591 DOI: 10.1007/s00709-015-0815-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/02/2015] [Indexed: 06/04/2023]
Abstract
One of the most conserved mechanisms for transmission of a nerve pulse across a synapse relies on acetylcholine (ACh). Ever since the Nobel Prize-winning works of Dale and Loewi, it has been assumed that ACh-subsequent to its action on a postsynaptic cell-is split into inactive by-products by acetylcholinesterase (AChE). Herein, the widespread assumption of inactivity of ACh's hydrolysis products is falsified. Excitable cells (Chara braunii internodes), which had previously been unresponsive to ACh, became ACh-sensitive in the presence of AChE. The latter was evidenced by a striking difference in cell membrane depolarization upon exposure to 10 mM intact ACh (∆V = -2 ± 5 mV) and its hydrolysate (∆V = 81 ± 19 mV), respectively, for 60 s. This pronounced depolarization, which also triggered action potentials, was clearly attributed to one of the hydrolysis products: acetic acid (∆V = 87 ± 9 mV at pH 4.0; choline ineffective in the range 1-10 mM). In agreement with our findings, numerous studies in the literature have reported that acids excite gels, lipid membranes, plant cells, erythrocytes, as well as neurons. Whether excitation of the postsynaptic cell in a cholinergic synapse is due to protons or due to intact ACh is a most fundamental question that has not been addressed so far.
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Affiliation(s)
- Christian Fillafer
- Biological Physics Group, Department of Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA, 02215, USA.
| | - Matthias F Schneider
- Biological Physics Group, Department of Mechanical Engineering, Boston University, 110 Cummington St., Boston, MA, 02215, USA
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Engi SA, Planeta CS, Crestani CC. Effect of Voluntary Ethanol Consumption Combined with Testosterone Treatment on Cardiovascular Function in Rats: Influence of Exercise Training. PLoS One 2016; 11:e0146974. [PMID: 26760038 PMCID: PMC4711937 DOI: 10.1371/journal.pone.0146974] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/23/2015] [Indexed: 01/15/2023] Open
Abstract
This study evaluated the effects of voluntary ethanol consumption combined with testosterone treatment on cardiovascular function in rats. Moreover, we investigated the influence of exercise training on these effects. To this end, male rats were submitted to low-intensity training on a treadmill or kept sedentary while concurrently being treated with ethanol for 6 weeks. For voluntary ethanol intake, rats were given access to two bottles, one containing ethanol and other containing water, three 24-hour sessions per week. In the last two weeks (weeks 5 and 6), animals underwent testosterone treatment concurrently with exercise training and exposure to ethanol. Ethanol consumption was not affected by either testosterone treatment or exercise training. Also, drug treatments did not influence the treadmill performance improvement evoked by training. However, testosterone alone, but not in combination with ethanol, reduced resting heart rate. Moreover, combined treatment with testosterone and ethanol reduced the pressor response to the selective α1-adrenoceptor agonist phenylephrine. Treatment with either testosterone or ethanol alone also affected baroreflex activity and enhanced depressor response to acetylcholine, but these effects were inhibited when drugs were coadministrated. Exercise training restored most cardiovascular effects evoked by drug treatments. Furthermore, both drugs administrated alone increased pressor response to phenylephrine in trained animals. Also, drug treatments inhibited the beneficial effects of training on baroreflex function. In conclusion, the present results suggest a potential interaction between toxic effects of testosterone and ethanol on cardiovascular function. Data also indicate that exercise training is an important factor influencing the effects of these substances.
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Affiliation(s)
- Sheila A. Engi
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista-UNESP, Araraquara, SP, Brazil
- Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
| | - Cleopatra S. Planeta
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista-UNESP, Araraquara, SP, Brazil
- Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
| | - Carlos C. Crestani
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Univ. Estadual Paulista-UNESP, Araraquara, SP, Brazil
- Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
- * E-mail:
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Abongwa M, Buxton SK, Robertson AP, Martin RJ. Curiouser and Curiouser: The Macrocyclic Lactone, Abamectin, Is also a Potent Inhibitor of Pyrantel/Tribendimidine Nicotinic Acetylcholine Receptors of Gastro-Intestinal Worms. PLoS One 2016; 11:e0146854. [PMID: 26751958 PMCID: PMC4709073 DOI: 10.1371/journal.pone.0146854] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 12/21/2015] [Indexed: 11/22/2022] Open
Abstract
Nematode parasites may be controlled with drugs, but their regular application has given rise to concerns about the development of resistance. Drug combinations may be more effective than single drugs and delay the onset of resistance. A combination of the nicotinic antagonist, derquantel, and the macrocyclic lactone, abamectin, has been found to have synergistic anthelmintic effects against gastro-intestinal nematode parasites. We have observed in previous contraction and electrophysiological experiments that derquantel is a potent selective antagonist of nematode parasite muscle nicotinic receptors; and that abamectin is an inhibitor of the same nicotinic receptors. To explore these inhibitory effects further, we expressed muscle nicotinic receptors of the nodular worm, Oesophagostomum dentatum (Ode-UNC-29:Ode-UNC-63:Ode-UNC-38), in Xenopus oocytes under voltage-clamp and tested effects of abamectin on pyrantel and acetylcholine responses. The receptors were antagonized by 0.03 μM abamectin in a non-competitive manner (reduced Rmax, no change in EC50). This antagonism increased when abamectin was increased to 0.1 μM. However, when we increased the concentration of abamectin further to 0.3 μM, 1 μM or 10 μM, we found that the antagonism decreased and was less than with 0.1 μM abamectin. The bi-phasic effects of abamectin suggest that abamectin acts at two allosteric sites: one high affinity negative allosteric (NAM) site causing antagonism, and another lower affinity positive allosteric (PAM) site causing a reduction in antagonism. We also tested the effects of 0.1 μM derquantel alone and in combination with 0.3 μM abamectin. We found that derquantel on these receptors, like abamectin, acted as a non-competitive antagonist, and that the combination of derquantel and abamectin produced greater inhibition. These observations confirm the antagonistic effects of abamectin on nematode nicotinic receptors in addition to GluCl effects, and illustrate more complex effects of macrocyclic lactones that may be exploited in combinations with other anthelmintics.
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Affiliation(s)
- Melanie Abongwa
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Samuel K. Buxton
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Alan P. Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Richard J. Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
- * E-mail:
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Li L, Liu N, Ding R, Wang S, Liu Z, Li H, Zheng X, Dai Q. A novel 4/6-type alpha-conotoxin ViIA selectively inhibits nAchR α3β2 subtype. Acta Biochim Biophys Sin (Shanghai) 2015; 47:1023-8. [PMID: 26511093 DOI: 10.1093/abbs/gmv105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 08/24/2015] [Indexed: 01/01/2023] Open
Abstract
Conotoxins (CTxs) are typically small peptides composed of 12-50 amino acid residues with 2-5 disulfide bridges. Most of them potently and selectively target a wide variety of ion channels and membrane receptors. They are highly valued as neuropharmacological probes and in pharmaceutical development. In this work, a novel α4/6-CTx named ViIA (RDCCSNPPCAHNNPDC-NH2) was identified from a cDNA library of the venom ducts of Conus virgo (C. virgo). ViIA was then synthesized chemically and its disulfide connectivity was identified as 'C(1)-C(3), C(2)-C(4)'. Its molecular targets were further assessed using two-electrode voltage clamping. The results indicated that ViIA selectively inhibited nicotinic acetylcholine receptor (nAChR) α3β2 subtype with an IC50 of 845.5 nM, but did not target dorsal root ganglion sodium (Na(+))-, potassium (K(+))- or calcium (Ca(2+))-ion channels. Further structure-activity relationship analysis demonstrated that Arg(1) and His(11) but not Asp(2) were the functional residues. To the best of our knowledge, ViIA is the first 4/6 α-CTx that selectively inhibits nAChR α3β2 subtype. This finding expands the knowledge of targets of α4/6-family CTxs.
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Affiliation(s)
- Liang Li
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China Beijing Institute of Biotechnology, Beijing 100071, China
| | - Na Liu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Rong Ding
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Shuo Wang
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Haiying Li
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Xing Zheng
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China
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Wang Y, Li S, Feng L, Nie C, Liu L, Lv F, Wang S. Fluorescence Ratiometric Assay Strategy for Chemical Transmitter of Living Cells Using H2O2-Sensitive Conjugated Polymers. ACS Appl Mater Interfaces 2015; 7:24110-24118. [PMID: 26451624 DOI: 10.1021/acsami.5b07172] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A new water-soluble conjugated poly(fluorene-co-phenylene) derivative (PFP-FB) modified with boronate-protected fluorescein (peroxyfluor-1) via PEG linker has been designed and synthesized. In the presence of H2O2, the peroxyfluor-1 group can transform into green fluorescent fluorescein by deprotecting the boronate protecting groups. In this case, upon selective excitation of PFP-FB backbone at 380 nm, efficient fluorescence resonance energy transfer (FRET) from PFP-FB backbone to fluorescein occurs, and accordingly, the fluorescence color of PFP-FB changes from blue to green. Furthermore, the emission color of PFP-FB and the FRET ratio change in a concentration-dependent manner. By taking advantage of PFP-FB, ratiometric detection of choline and acetylcholine (ACh) through cascade enzymatic reactions and further dynamic monitoring of the choline consumption process of cancer cells have been successfully realized. Thus, this new polymer probe promotes the development of enzymatic biosensors and provides a simpler and more effective way for detecting the chemical transmitter of living cells.
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Affiliation(s)
- Yunxia Wang
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Shengliang Li
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Liheng Feng
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Chenyao Nie
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Libing Liu
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Fengting Lv
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
| | - Shu Wang
- Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China
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Colombo ML, Sweedler JV, Shen M. Nanopipet-Based Liquid-Liquid Interface Probes for the Electrochemical Detection of Acetylcholine, Tryptamine, and Serotonin via Ionic Transfer. Anal Chem 2015; 87:5095-100. [PMID: 25877788 PMCID: PMC4483307 DOI: 10.1021/ac504151e] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A nanoscale interface between two immiscible electrolyte solutions (ITIES) provides a unique analytical platform for the detection of ionic species of biological interest such as neurotransmitters and neuromodulators, especially those that are otherwise difficult to detect directly on a carbon electrode without electrode modification. We report the detection of acetylcholine, serotonin, and tryptamine on nanopipet electrode probes with sizes ranging from a radius of ≈7 to 35 nm. The transfer of these analytes across a 1,2-dichloroethane/water interface was studied by cyclic voltammetry and amperometry. Well-defined sigmoidal voltammograms were observed on the nanopipet electrodes within the potential window of artificial seawater for acetylcholine and tryptamine. The half wave transfer potential, E1/2, of acetylcholine, tryptamine, and serotonin were found to be -0.11, -0.25, and -0.47 V vs E(1/2,TEA) (term is defined later in experimental), respectively. The detection was linear in the range of 0.25-6 mM for acetylcholine and of 0.5-10 mM for tryptamine in artificial seawater. Transfer of serotonin was linear in the range of 0.15-8 mM in LiCl solution. The limit of detection for serotonin in LiCl on a radius ≈21 nm nanopipet electrode was 77 μM, for acetylcholine on a radius ≈7 nm nanopipet electrode was 205 μM, and for tryptamine on a radius ≈19 nm nanopipet electrode was 86 μM. Nanopipet-supported ITIES probes have great potential to be used in nanometer spatial resolution measurements for the detection of neurotransmitters.
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Affiliation(s)
- Michelle L. Colombo
- Department of Chemistry, University of Illinois at Urbana–Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Jonathan V. Sweedler
- Department of Chemistry, University of Illinois at Urbana–Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Mei Shen
- Department of Chemistry, University of Illinois at Urbana–Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
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Chen X, Huang X, Geng L, Xue L, Hou S, Zheng X, Brimijoin S, Zheng F, Zhan CG. Kinetic characterization of a cocaine hydrolase engineered from mouse butyrylcholinesterase. Biochem J 2015; 466:243-51. [PMID: 25486543 PMCID: PMC4367957 DOI: 10.1042/bj20141266] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mouse butyrylcholinesterase (mBChE) and an mBChE-based cocaine hydrolase (mCocH, i.e. the A¹⁹⁹S/S²²⁷A/S²⁸⁷G/A³²⁸W/Y³³²G mutant) have been characterized for their catalytic activities against cocaine, i.e. naturally occurring (-)-cocaine, in comparison with the corresponding human BChE (hBChE) and an hBChE-based cocaine hydrolase (hCocH, i.e. the A¹⁹⁹S/F²²⁷A/S²⁸⁷G/A³²⁸W/Y³³²G mutant). It has been demonstrated that mCocH and hCocH have improved the catalytic efficiency of mBChE and hBChE against (-)-cocaine by ~8- and ~2000-fold respectively, although the catalytic efficiencies of mCocH and hCocH against other substrates, including acetylcholine (ACh) and butyrylthiocholine (BTC), are close to those of the corresponding wild-type enzymes mBChE and hBChE. According to the kinetic data, the catalytic efficiency (k(cat)/K(M)) of mBChE against (-)-cocaine is comparable with that of hBChE, but the catalytic efficiency of mCocH against (-)-cocaine is remarkably lower than that of hCocH by ~250-fold. The remarkable difference in the catalytic activity between mCocH and hCocH is consistent with the difference between the enzyme-(-)-cocaine binding modes obtained from molecular modelling. Further, both mBChE and hBChE demonstrated substrate activation for all of the examined substrates [(-)-cocaine, ACh and BTC] at high concentrations, whereas both mCocH and hCocH showed substrate inhibition for all three substrates at high concentrations. The amino-acid mutations have remarkably converted substrate activation of the enzymes into substrate inhibition, implying that the rate-determining step of the reaction in mCocH and hCocH might be different from that in mBChE and hBChE.
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Affiliation(s)
- Xiabin Chen
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Xiaoqin Huang
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Liyi Geng
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905
| | - Liu Xue
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Shurong Hou
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Xirong Zheng
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Stephen Brimijoin
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905
| | - Fang Zheng
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
| | - Chang-Guo Zhan
- Molecular Modeling and Biopharmaceutical Center and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536
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Nichols WA, Henderson BJ, Yu C, Parker RL, Richards CI, Lester HA, Miwa JM. Lynx1 shifts α4β2 nicotinic receptor subunit stoichiometry by affecting assembly in the endoplasmic reticulum. J Biol Chem 2014; 289:31423-32. [PMID: 25193667 PMCID: PMC4223341 DOI: 10.1074/jbc.m114.573667] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/30/2014] [Indexed: 01/11/2023] Open
Abstract
Glycosylphosphatidylinositol-anchored neurotoxin-like receptor binding proteins, such as lynx modulators, are topologically positioned to exert pharmacological effects by binding to the extracellular portion of nAChRs. These actions are generally thought to proceed when both lynx and the nAChRs are on the plasma membrane. Here, we demonstrate that lynx1 also exerts effects on α4β2 nAChRs within the endoplasmic reticulum. Lynx1 affects assembly of nascent α4 and β2 subunits and alters the stoichiometry of the receptor population that reaches the plasma membrane. Additionally, these data suggest that lynx1 shifts nAChR stoichiometry to low sensitivity (α4)3(β2)2 pentamers primarily through this interaction in the endoplasmic reticulum, rather than solely via direct modulation of activity on the plasma membrane. To our knowledge, these data represent the first test of the hypothesis that a lynx family member, or indeed any glycosylphosphatidylinositol-anchored protein, could act within the cell to alter assembly of a multisubunit protein.
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Affiliation(s)
- Weston A Nichols
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brandon J Henderson
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Caroline Yu
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Rell L Parker
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | | | - Henry A Lester
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Julie M Miwa
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
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Xing D, Ma L, Gao C. Synthesis of poly(ester-carbonate) with a pendant acetylcholine analog for promoting neurite growth. Acta Biomater 2014; 10:4127-35. [PMID: 24998182 DOI: 10.1016/j.actbio.2014.06.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 06/16/2014] [Accepted: 06/23/2014] [Indexed: 01/08/2023]
Abstract
The modification of biodegradable polyesters with bioactive molecules has become an important strategy for controlling neuron adhesion and neurite outgrowth in nerve regeneration. In this study we report a biodegradable poly(ester-carbonate) with a pendant acetylcholine analog, which a neurotransmitter for the enhancement of neuron adhesion and outgrowth. The acetylcholine-functionalized poly(ester-carbonate) (Ach-P(LA-ClTMC)) was prepared by copolymerizing l-lactide (LA) and 5-methyl-5-chloroethoxycarbonyl trimethylene carbonate (ClTMC), followed by quaternization with trimethylamine. The acetylcholine analog content could be modulated by changing the molar feeding fraction of ClTMC. The incorporation of the acetylcholine analog improved the hydrophilicity of the films, but the acetylcholine analog content did not significantly influence the surface morphology of the acetylcholine-functionalized films. The results of PC12 cell culture showed that the acetylcholine analog promoted cell viability and neurite outgrowth in a concentration-dependent manner. The longest length of neurite and the percentage of cells bearing neurites were obtained on the Ach-P(LA-ClTMC)-10 film. All the results indicate that the integration of the acetylcholine analog at an appropriate fraction could be an effective strategy for optimizing the existing biodegradable polyesters for nerve regeneration applications.
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Affiliation(s)
- Dongming Xing
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Lie Ma
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
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30
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Mu L, Droujinine IA, Rajan NK, Sawtelle SD, Reed MA. Direct, rapid, and label-free detection of enzyme-substrate interactions in physiological buffers using CMOS-compatible nanoribbon sensors. Nano Lett 2014; 14:5315-22. [PMID: 25164567 DOI: 10.1021/nl502366e] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We demonstrate the versatility of Al2O3-passivated Si nanowire devices ("nanoribbons") in the analysis of enzyme-substrate interactions via the monitoring of pH change. Our approach is shown to be effective through the detection of urea in phosphate buffered saline (PBS), and penicillinase in PBS and urine, at limits of detection of <200 μM and 0.02 units/mL, respectively. The ability to extract accurate enzyme kinetics and the Michaelis-Menten constant (Km) from the acetylcholine-acetylcholinesterase reaction is also demonstrated.
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Affiliation(s)
- Luye Mu
- Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States
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Peters GH, Werge M, Elf-Lind MN, Madsen JJ, Velardez GF, Westh P. Interaction of neurotransmitters with a phospholipid bilayer: a molecular dynamics study. Chem Phys Lipids 2014; 184:7-17. [PMID: 25159594 DOI: 10.1016/j.chemphyslip.2014.08.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/14/2014] [Accepted: 08/22/2014] [Indexed: 11/15/2022]
Abstract
We have performed a series of molecular dynamics simulations to study the interactions between the neurotransmitters (NTs) γ-aminobutyrate (GABA), glycine (GLY), acetylcholine (ACH) and glutamate (GLU) as well as the amidated/acetylated γ-aminobutyrate (GABA(neu)) and the osmolyte molecule glycerol (GOL) with a dipalmitoylphosphatidylcholine (DPPC) bilayer. In agreement with previously published experimental data, we found the lowest membrane affinity for the charged molecules and a moderate affinity for zwitterionic and polar molecules. The affinity can be ranked as follows: ACH-GLU<<GABA<GLY<<GABA(neu)<<GOL. The latter three penetrated the bilayer at most with the deepest location being close to the glycerol backbone of the phospholipids. Even at that position, these solutes were noticeably hydrated and carried ∼30-80% of the bulk water along. The mobility of hydration water at the solute is also affected by the penetration into the bilayer. Two time scales of exchanging water molecules could be determined. In the bulk phase, the hydration layer contains ∼20% slow exchanging water molecules which increases 2-3 times as the solutes entered the bilayer. Our results indicate that there is no intermediate exchange of slow moving water molecules from the solutes to the lipid atoms and vice versa. Instead, the exchange relies on the reservoir of unbounded ("free") water molecules in the interfacial bilayer region. Results from the equilibrium simulations are in good agreement with the results from umbrella sampling simulations, which were conducted for the four naturally occurring NTs. Free energy profiles for ACH and GLU show a minimum of ∼2-3 kJ/mol close to the bilayer interface, while for GABA and GLY, a minimum of respectively ∼2 kJ/mol and ∼5 kJ/mol is observed when these NTs are located in the vicinity of the lipid glycerol backbone. The most important interaction of NTs with the bilayer is the charged amino group of NTs with the lipid phosphate group.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark.
| | - Mikkel Werge
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | | | - Jesper J Madsen
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Gustavo F Velardez
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Peter Westh
- NSM, Research Unit for Functional Biomaterials, Roskilde University, Roskilde 4000, Denmark.
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Purohit P, Bruhova I, Gupta S, Auerbach A. Catch-and-hold activation of muscle acetylcholine receptors having transmitter binding site mutations. Biophys J 2014; 107:88-99. [PMID: 24988344 PMCID: PMC4119287 DOI: 10.1016/j.bpj.2014.04.057] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 11/18/2022] Open
Abstract
Agonists turn on receptors because their target sites have a higher affinity in the active versus resting conformation of the protein. We used single-channel electrophysiology to measure the lower-affinity (LA) and higher-affinity (HA) equilibrium dissociation constants for acetylcholine in adult-type muscle mouse nicotinic receptors (AChRs) having mutations of agonist binding site amino acids. For a series of agonists and for all mutations of αY93, αG147, αW149, αY190, αY198, εW55, and δW57, the change in LA binding energy was approximately half that in HA binding energy. The results were analyzed as a linear free energy relationship between LA and HA agonist binding, the slope of which (κ) gives the fraction of the overall binding chemical potential where the LA complex is established. The linear correlation between LA and HA binding energies suggests that the overall binding process is by an integrated mechanism (catch-and-hold). For the agonist and the above mutations, κ ∼ 0.5, but side-chain substitutions of two residues had a slope that was significantly higher (0.90; αG153) or lower (0.25; εP121). The results suggest that backbone rearrangements in loop B, loop C, and the non-α surface participate in both LA binding and the LA ↔ HA affinity switch. It appears that all of the intermediate steps in AChR activation comprise a single, energetically coupled process.
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Affiliation(s)
- Prasad Purohit
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York
| | - Iva Bruhova
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York
| | - Shaweta Gupta
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York
| | - Anthony Auerbach
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York.
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Olsen JA, Balle T, Gajhede M, Ahring PK, Kastrup JS. Molecular recognition of the neurotransmitter acetylcholine by an acetylcholine binding protein reveals determinants of binding to nicotinic acetylcholine receptors. PLoS One 2014; 9:e91232. [PMID: 24637639 PMCID: PMC3956608 DOI: 10.1371/journal.pone.0091232] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 02/10/2014] [Indexed: 11/24/2022] Open
Abstract
Despite extensive studies on nicotinic acetylcholine receptors (nAChRs) and homologues, details of acetylcholine binding are not completely resolved. Here, we report the crystal structure of acetylcholine bound to the receptor homologue acetylcholine binding protein from Lymnaea stagnalis. This is the first structure of acetylcholine in a binding pocket containing all five aromatic residues conserved in all mammalian nAChRs. The ligand-protein interactions are characterized by contacts to the aromatic box formed primarily by residues on the principal side of the intersubunit binding interface (residues Tyr89, Trp143 and Tyr185). Besides these interactions on the principal side, we observe a cation-π interaction between acetylcholine and Trp53 on the complementary side and a water-mediated hydrogen bond from acetylcholine to backbone atoms of Leu102 and Met114, both of importance for anchoring acetylcholine to the complementary side. To further study the role of Trp53, we mutated the corresponding tryptophan in the two different acetylcholine-binding interfaces of the widespread α4β2 nAChR, i.e. the interfaces α4(+)β2(−) and α4(+)α4(−). Mutation to alanine (W82A on the β2 subunit or W88A on the α4 subunit) significantly altered the response to acetylcholine measured by oocyte voltage-clamp electrophysiology in both interfaces. This shows that the conserved tryptophan residue is important for the effects of ACh at α4β2 nAChRs, as also indicated by the crystal structure. The results add important details to the understanding of how this neurotransmitter exerts its action and improves the foundation for rational drug design targeting these receptors.
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Affiliation(s)
- Jeppe A. Olsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- NeuroSearch A/S, Ballerup, Denmark
| | - Thomas Balle
- Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
| | - Michael Gajhede
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philip K. Ahring
- Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
- Aniona ApS, Ballerup, Denmark
| | - Jette S. Kastrup
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
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Purón-Sierra L, Miranda MI. Histaminergic modulation of cholinergic release from the nucleus basalis magnocellularis into insular cortex during taste aversive memory formation. PLoS One 2014; 9:e91120. [PMID: 24625748 PMCID: PMC3953328 DOI: 10.1371/journal.pone.0091120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 02/07/2014] [Indexed: 11/19/2022] Open
Abstract
The ability of acetylcholine (ACh) to alter specific functional properties of the cortex endows the cholinergic system with an important modulatory role in memory formation. For example, an increase in ACh release occurs during novel stimulus processing, indicating that ACh activity is critical during early stages of memory processing. During novel taste presentation, there is an increase in ACh release in the insular cortex (IC), a major structure for taste memory recognition. There is extensive evidence implicating the cholinergic efferents of the nucleus basalis magnocellularis (NBM) in cortical activity changes during learning processes, and new evidence suggests that the histaminergic system may interact with the cholinergic system in important ways. However, there is little information as to whether changes in cholinergic activity in the IC are modulated during taste memory formation. Therefore, in the present study, we evaluated the influence of two histamine receptor subtypes, H1 in the NBM and H3 in the IC, on ACh release in the IC during conditioned taste aversion (CTA). Injection of the H3 receptor agonist R-α-methylhistamine (RAMH) into the IC or of the H1 receptor antagonist pyrilamine into the NBM during CTA training impaired subsequent CTA memory, and simultaneously resulted in a reduction of ACh release in the IC. This study demonstrated that basal and cortical cholinergic pathways are finely tuned by histaminergic activity during CTA, since dual actions of histamine receptor subtypes on ACh modulation release each have a significant impact during taste memory formation.
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Affiliation(s)
- Liliana Purón-Sierra
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Qro., México
| | - María Isabel Miranda
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Qro., México
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Tu Q, Pang L, Wang L, Zhang Y, Zhang R, Wang J. Biomimetic choline-like graphene oxide composites for neurite sprouting and outgrowth. ACS Appl Mater Interfaces 2013; 5:13188-13197. [PMID: 24313218 DOI: 10.1021/am4042004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Neurodegenerative diseases or acute injuries of the nervous system always lead to neuron loss and neurite damage. Thus, the development of effective methods to repair these damaged neurons is necessary. The construction of biomimetic materials with specific physicochemical properties is a promising solution to induce neurite sprouting and guide the regenerating nerve. Herein, we present a simple method for constructing biomimetic graphene oxide (GO) composites by covalently bonding an acetylcholine-like unit (dimethylaminoethyl methacrylate, DMAEMA) or phosphorylcholine-like unit (2-methacryloyloxyethyl phosphorylcholine, MPC) onto GO surfaces to enhance neurite sprouting and outgrowth. The resulting GO composites were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, UV-vis spectrometry, scanning electron microscopy, and contact angle analyses. Primary rat hippocampal neurons were used to investigate nerve cell adhesion, spreading, and proliferation on these biomimetic GO composites. GO-DMAEMA and GO-MPC composites provide the desired biomimetic properties for superior biocompatibility without affecting cell viability. At 2 to 7 days after cell seeding was performed, the number of neurites and average neurite length on GO-DMAEMA and GO-MPC composites were significantly enhanced compared with the control GO. In addition, analysis of growth-associate protein-43 (GAP-43) by Western blot showed that GAP-43 expression was greatly improved in biomimetic GO composite groups compared to GO groups, which might promote neurite sprouting and outgrowth. All the results demonstrate the potential of DMAEMA- and MPC-modified GO composites as biomimetic materials for neural interfacing and provide basic information for future biomedical applications of graphene oxide.
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Affiliation(s)
- Qin Tu
- College of Science and ‡College of Veterinary Medicine, Northwest A&F University , Yangling, Shaanxi 712100, People's Republic of China
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Abstract
Cocaine is one of the most addictive drugs, and there is still no FDA (Food and Drug Administration)-approved medication specific for cocaine abuse. A promising therapeutic strategy is to accelerate cocaine metabolism, producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e. cocaine hydrolysis catalyzed by butyrylcholinesterase (BChE) in plasma. However, the native BChE has a low catalytic efficiency against the abused cocaine, i.e. (-)-cocaine. Our recently designed and discovered A199S/F227A/S287G/A328W/Y332G mutant and other mutants of human BChE have a considerably improved catalytic efficiency against (-)-cocaine. In the present study, we carried out both computational modeling and experimental kinetic analysis on the catalytic activities of these promising new BChE mutants against other known substrates, including neurotransmitter acetylcholine (ACh), acetylthiocholine (ATC), butyrylthiocholine (BTC), and (+)-cocaine, in comparison with the corresponding catalytic activity against (-)-cocaine. Both the computational modeling and kinetic analysis have consistently revealed that all the examined amino acid mutations only considerably improve the catalytic efficiency of human BChE against (-)-cocaine, without significantly improving the catalytic efficiency of the enzyme against any of the other substrates examined. In particular, all the examined BChE mutants have a slightly lower catalytic efficiency against neurotransmitter ACh compared to the wild-type BChE. This observation gives us confidence in developing an anti-cocaine enzyme therapy by using one of these BChE mutants, particularly the A199S/F227A/S287G/A328W/Y332G mutant.
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Affiliation(s)
- Shurong Hou
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536, USA.
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Esparza-Martín N, Suria-González S, García-Cantón C, Ramírez-Puga A, Guerra-Rodríguez R, Checa-Andrés MD. Effect of allopurinol on smoking. Nefrologia 2013; 33:858-860. [PMID: 24241378 DOI: 10.3265/nefrologia.pre2013.aug.11863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2013] [Indexed: 06/02/2023] Open
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Peterson KM, Franchi F, Loeffler DL, Psaltis PJ, Harris PC, Lerman LO, Lerman A, Rodriguez-Porcel M. Endothelial dysfunction occurs prior to clinical evidence of polycystic kidney disease. Am J Nephrol 2013; 38:233-40. [PMID: 24008943 DOI: 10.1159/000354236] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/17/2013] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Polycystic kidney disease (PKD), a monogenic disease with an autosomal dominant or an autosomal recessive form of inheritance (ARPKD), is the most common genetic cause of renal dysfunction and end-stage renal failure. In addition to the development of cysts, the autosomal form of PKD is associated with vascular endothelial dysfunction, a marker of vascular disease. Whether vascular endothelial dysfunction is also present in ARPKD, and its relationship with renal dysfunction remain to be determined. METHODS ARPKD rats (PCK model) and controls were studied at 6 and 10 weeks of age, and mean arterial pressure and renal function were measured. Aortic endothelial function was assessed using organ chamber techniques. Aortic endothelial cells (ECs) were isolated, characterized and their function studied. RESULTS Compared to controls, ARPKD animals had a decrease in the vasorelaxation to endothelium-dependent vasodilators, even prior to changes in mean arterial pressure or renal function. The abnormal vasoreactivity was corrected with L-arginine (a precursor of nitric oxide, NO), while the expression of endothelial NO synthase (eNOS) was unchanged. Furthermore, isolated ECs from 6-week-old ARPKD animals showed increased oxidative stress, with preserved eNOS expression and abnormal patterns of migration and angiogenic capacity (measured by the scratch and tube formation assays, respectively). CONCLUSION ARPKD leads to impairments in aortic vascular function and ECs at an early stage, which can have significant functional consequences, potentially representing a novel therapeutic target in this disease.
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Affiliation(s)
- Karen M Peterson
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minn., USA
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Sengupta A, Ghosh S, Sharma S, Sonawat HM. 1H NMR metabonomics indicates continued metabolic changes and sexual dimorphism post-parasite clearance in self-limiting murine malaria model. PLoS One 2013; 8:e66954. [PMID: 23826178 PMCID: PMC3691208 DOI: 10.1371/journal.pone.0066954] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 05/13/2013] [Indexed: 11/18/2022] Open
Abstract
Malaria, a mosquito-borne disease caused by Plasmodium spp. is considered to be a global threat, specifically for the developing countries. In human subjects considerable information exists regarding post-malarial physiology. However, most murine malarial models are lethal, and most studies deal with acute phases occurring as disease progresses. Much less is known regarding physiological status post-parasite clearance. We have assessed the physiological changes at the organ levels using (1)H NMR based metabonomics in a non lethal self-clearing murine malarial model of P. chabaudi parasites and Balb/C, far beyond the parasite clearance point. The results showed distinct metabolic states between uninfected and infected mice at the peak parasitemia, as well as three weeks post-parasite clearance. Our data also suggests that the response at the peak infection as well as recovery exhibited distinct sexual dimorphism. Specifically, we observed accumulation of acetylcholine in the brain metabolic profile of both the sexes. This might have important implication in understanding the pathophysiology of the post malarial neurological syndromes. In addition, the female liver showed high levels of glucose, dimethylglycine, methylacetoacetate and histidine after three weeks post-parasite clearance, while the males showed accumulation of branched chain amino acids, lysine, glutamine and bile acids.
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Affiliation(s)
- Arjun Sengupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Soumita Ghosh
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Shobhona Sharma
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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Quinton L, Servent D, Girard E, Molgó J, Le Caer JP, Malosse C, Haidar EA, Lecoq A, Gilles N, Chamot-Rooke J. Identification and functional characterization of a novel α-conotoxin (EIIA) from Conus ermineus. Anal Bioanal Chem 2013; 405:5341-51. [PMID: 23584713 DOI: 10.1007/s00216-013-6926-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/14/2013] [Accepted: 03/18/2013] [Indexed: 01/22/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are one of the most important families in the ligand-gated ion channel superfamily due to their involvement in primordial brain functions and in several neurodegenerative pathologies. The discovery of new ligands which can bind with high affinity and selectivity to nAChR subtypes is of prime interest in order to study these receptors and to potentially discover new drugs for treating various pathologies. Predatory cone snails of the genus Conus hunt their prey using venoms containing a large number of small, highly structured peptides called conotoxins. Conotoxins are classified in different structural families and target a large panel of receptors and ion channels. Interestingly, nAChRs represent the only subgroup for which Conus has developed seven distinct families of conotoxins. Conus venoms have thus received much attention as they could represent a potential source of selective ligands of nAChR subtypes. We describe the mass spectrometric-based approaches which led to the discovery of a novel α-conotoxin targeting muscular nAChR from the venom of Conus ermineus. The presence of several posttranslational modifications complicated the N-terminal sequencing. To discriminate between the different possible sequences, analogs with variable N-terminus were synthesized and fragmented by MS/MS. Understanding the fragmentation pathways in the low m/z range appeared crucial to determine the right sequence. The biological activity of this novel α-conotoxin (α-EIIA) that belongs to the unusual α4/4 subfamily was determined by binding experiments. The results revealed not only its selectivity for the muscular nAChR, but also a clear discrimination between the two binding sites described for this receptor.
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Affiliation(s)
- Loïc Quinton
- Laboratoire des Mécanismes Réactionnels, Département de Chimie, Ecole Polytechnique, CNRS UMR7651, 91128 Palaiseau Cedex, France
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Haga T. Molecular properties of muscarinic acetylcholine receptors. Proc Jpn Acad Ser B Phys Biol Sci 2013; 89:226-256. [PMID: 23759942 PMCID: PMC3749793 DOI: 10.2183/pjab.89.226] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Accepted: 04/30/2013] [Indexed: 05/28/2023]
Abstract
Muscarinic acetylcholine receptors, which comprise five subtypes (M1-M5 receptors), are expressed in both the CNS and PNS (particularly the target organs of parasympathetic neurons). M1-M5 receptors are integral membrane proteins with seven transmembrane segments, bind with acetylcholine (ACh) in the extracellular phase, and thereafter interact with and activate GTP-binding regulatory proteins (G proteins) in the intracellular phase: M1, M3, and M5 receptors interact with Gq-type G proteins, and M2 and M4 receptors with Gi/Go-type G proteins. Activated G proteins initiate a number of intracellular signal transduction systems. Agonist-bound muscarinic receptors are phosphorylated by G protein-coupled receptor kinases, which initiate their desensitization through uncoupling from G proteins, receptor internalization, and receptor breakdown (down regulation). Recently the crystal structures of M2 and M3 receptors were determined and are expected to contribute to the development of drugs targeted to muscarinic receptors. This paper summarizes the molecular properties of muscarinic receptors with reference to the historical background and bias to studies performed in our laboratories.
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Mahajan S, Sharma R, Mahajan RK. An investigation of drug binding ability of a surface active ionic liquid: micellization, electrochemical, and spectroscopic studies. Langmuir 2012; 28:17238-46. [PMID: 23214438 DOI: 10.1021/la303193n] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Keeping in view the use of surfactants in drug delivery, the interactions of surface active ionic liquids, such as 1-tetradecyl-3-methylimidazolium bromide (C(14)mimBr), with drugs, viz., dopamine hydrochloride (DH) and acetylcholine chloride (AC), have been studied, and the results are further compared with that of the structurally similar conventional cationic surfactant tetradecyltrimethylammonium bromide (TTAB). The micellization and interfacial behavior of C(14)mimBr and TTAB, in the presence of DH and AC, has been investigated from conductivity and surface tension measurements. Various micellar and adsorption characteristics for these drug-surfactant systems (DH/AC + C(14)mimBr/TTAB) have been investigated, indicating favorable interactions between them. The more detailed information regarding the nature of interactions between C(14)mimBr/TTAB and DH/AC is obtained from cyclic voltammetry (CV) and (1)H NMR measurements. CV measurements have been employed to evaluate the binding constant (K) and the Gibbs free energy change (ΔG) for these drug-surfactant complexes. These measurements indicate the existence of cation-π as well as π-π interactions between drugs and surfactants. A detailed analysis of chemical shifts of protons of drug molecules (DH and AC) in the presence of C(14)mimBr and TTAB has been done by (1)H NMR. The results obtained from (1)H NMR are in agreement with those of CV measurements. (1)H NMR studies along with the conductivity and surface tension measurements help in predicting the possible location of adsorption of these drug molecules in C(14)mimBr and TTAB micelles.
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Affiliation(s)
- Suruchi Mahajan
- Department of Chemistry, UGC-Centre for Advanced Studies, Guru Nanak Dev University, Amritsar-143005, India
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Abstract
The modulation of pentameric ligand-gated ion channels (pLGICs) by divalent cations is believed to play an important role in their regulation in a physiological context. Ions such as calcium or zinc influence the activity of pLGIC neurotransmitter receptors by binding to their extracellular domain and either potentiate or inhibit channel activation. Here we have investigated by electrophysiology and X-ray crystallography the effect of divalent ions on ELIC, a close prokaryotic pLGIC homologue of known structure. We found that divalent cations inhibit the activation of ELIC by the agonist cysteamine, reducing both its potency and, at higher concentrations, its maximum response. Crystal structures of the channel in complex with barium reveal the presence of several distinct binding sites. By mutagenesis we confirmed that the site responsible for divalent inhibition is located at the outer rim of the extracellular domain, at the interface between adjacent subunits but at some distance from the agonist binding region. Here, divalent cations interact with the protein via carboxylate side-chains, and the site is similar in structure to calcium binding sites described in other proteins. There is evidence that other pLGICs may be regulated by divalent ions binding to a similar region, even though the interacting residues are not conserved within the family. Our study provides structural and functional insight into the allosteric regulation of ELIC and is of potential relevance for the entire family.
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Affiliation(s)
- Iwan Zimmermann
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Alessandro Marabelli
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Carlo Bertozzi
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Lucia G. Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Raimund Dutzler
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
- * E-mail:
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Torres JM, Lira AF, Silva DR, Guzzo LM, Sant'Anna CMR, Kümmerle AE, Rumjanek VM. Structural insights into cholinesterases inhibition by harmane β-carbolinium derivatives: a kinetics-molecular modeling approach. Phytochemistry 2012; 81:24-30. [PMID: 22717507 DOI: 10.1016/j.phytochem.2012.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 02/23/2012] [Accepted: 05/01/2012] [Indexed: 05/27/2023]
Abstract
The natural indole alkaloids, the β-carbolines, are often associated with cholinesterase inhibition, especially their quaternary salts, which frequently have higher activity than the free bases. Due to lack of information explaining this fact in the literature, the cholinesterase inhibition by the natural product harmane and its two β-carbolinium synthetic derivative salts (N-methyl and N-ethyl) was explored, together with a combination of kinetics and a molecular modeling approach. The results, mainly for the β-carbolinium salts, demonstrated a noncompetitive inhibition profile, ruling out previous findings which associated cholinesterase inhibition by β-carbolinium salts to a possible mimicking of the choline moiety of the natural substrate, acetylcholine. Molecular modeling studies corroborate this kind of inhibition through analyses of inhibitor/enzyme and inhibitor/substrate/enzyme complexes of both enzymes.
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Affiliation(s)
- Juliana M Torres
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, Brazil
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Xian YF, Lin ZX, Zhao M, Mao QQ, Ip SP, Che CT. Uncaria rhynchophylla ameliorates cognitive deficits induced by D-galactose in mice. Planta Med 2011; 77:1977-1983. [PMID: 21858756 DOI: 10.1055/s-0031-1280125] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The stem with hooks of Uncaria rhynchophylla is a component herb of many traditional formulae for the treatment of neurodegenerative diseases. However, scientific evidence of the efficacy of Uncaria rhynchophylla in the treatment of Alzheimer's disease (AD) in animal models is lacking. Thus, in the present study, we investigated whether the 70 % aqueous ethanol extract of Uncaria rhynchophylla (EUR) could protect against D-galactose (D-gal)-induced cognitive deficits in mice. Mice were given a subcutaneous injection of D-gal (50 mg/kg) and orally administered EUR (100, 200, or 400 mg/kg) daily for 8 weeks. The effect of EUR on D-gal-induced cognitive deficits was evaluated by measuring behavioral and neurochemical parameters of AD and the antioxidant status of brain tissue. The results showed that EUR (200 or 400 mg/kg) significantly increased exploratory behavior (assessed by an open-field test) and improved spatial learning and memory function (assessed by the Morris water maze test) in D-gal-treated mice. In addition, EUR (200 or 400 mg/kg) significantly increased the levels of acetylcholine and glutathione and decreased the activity of acetylcholinesterase and the level of malondialdehyde in the brains of D-gal-treated mice. These results indicate that EUR ameliorates cognitive deficits induced by D-gal in mice, and that this action may be mediated, at least in part, by the inhibition of acetylcholinesterase activity and the enhancement of the antioxidant status of brain tissue.
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Affiliation(s)
- Yan-Fang Xian
- School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong SAR, China
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Suratman S, Leach K, Sexton P, Felder C, Loiacono R, Christopoulos A. Impact of species variability and 'probe-dependence' on the detection and in vivo validation of allosteric modulation at the M4 muscarinic acetylcholine receptor. Br J Pharmacol 2011; 162:1659-70. [PMID: 21198541 PMCID: PMC3057301 DOI: 10.1111/j.1476-5381.2010.01184.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 10/28/2010] [Accepted: 11/25/2010] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE We recently characterized LY2033298 as a novel allosteric modulator and agonist at M(4) muscarinic acetylcholine receptors (mAChRs). Evidence also suggested a difference in the potency of LY2033298 at rodent relative to human M(4) mAChRs. The current study investigated the basis for the species difference of this modulator and used this knowledge to rationalize its in vivo actions. EXPERIMENTAL APPROACH LY2033298 was investigated in vitro in CHO cells stably expressing human or mouse M(4) mAChRs, using assays of agonist-induced ERK1/2 or GSK-3α phosphorylation, [(35) S]-GTPγS binding, or effects on equilibrium binding of [(3) H]-NMS and ACh. The in vivo actions of LY2033298 were investigated in a mouse model of amphetamine-induced locomotor activity. The function of LY2033298 was examined in combination with ACh, oxotremorine or xanomeline. KEY RESULTS LY2033298 had similar affinities for the human and mouse M(4) mAChRs. However, LY2033298 had a lower positive co-operativity with ACh at the mouse relative to the human M(4) mAChR. At the mouse M(4) mAChR, LY2033298 showed higher co-operativity with oxotremorine than with ACh or xanomeline. The different degrees of co-operativity between LY2033298 and each agonist at the mouse relative to the human M(4) mAChR necessitated the co-administration of LY2033298 with oxotremorine in order to show in vivo efficacy of LY2033298. CONCLUSIONS AND IMPLICATIONS These results provide evidence for species variability when comparing the allosteric interaction between LY2033298 and ACh at the M(4) mAChR, and also highlight how the interaction between LY2033298 and different orthosteric ligands is subject to 'probe dependence'. This has implications for the validation of allosteric modulator actions in vivo.
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Affiliation(s)
- S Suratman
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Vic., Australia
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Wagner S, Kufleitner J, Zensi A, Dadparvar M, Wien S, Bungert J, Vogel T, Worek F, Kreuter J, von Briesen H. Nanoparticulate transport of oximes over an in vitro blood-brain barrier model. PLoS One 2010; 5:e14213. [PMID: 21151975 PMCID: PMC2997055 DOI: 10.1371/journal.pone.0014213] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 11/09/2010] [Indexed: 11/19/2022] Open
Abstract
Background Due to the use of organophosphates (OP) as pesticides and the availability of OP-type nerve agents, an effective medical treatment for OP poisonings is still a challenging problem. The acute toxicity of an OP poisoning is mainly due to the inhibition of acetylcholinesterase (AChE) in the peripheral and central nervous systems (CNS). This results in an increase in the synaptic concentration of the neurotransmitter acetylcholine, overstimulation of cholinergic receptors and disorder of numerous body functions up to death. The standard treatment of OP poisoning includes a combination of a muscarinic antagonist and an AChE reactivator (oxime). However, these oximes can not cross the blood-brain barrier (BBB) sufficiently. Therefore, new strategies are needed to transport oximes over the BBB. Methodology/Principal Findings In this study, we combined different oximes (obidoxime dichloride and two different HI 6 salts, HI 6 dichloride monohydrate and HI 6 dimethanesulfonate) with human serum albumin nanoparticles and could show an oxime transport over an in vitro BBB model. In general, the nanoparticulate transported oximes achieved a better reactivation of OP-inhibited AChE than free oximes. Conclusions/Significance With these nanoparticles, for the first time, a tool exists that could enable a transport of oximes over the BBB. This is very important for survival after severe OP intoxication. Therefore, these nanoparticulate formulations are promising formulations for the treatment of the peripheral and the CNS after OP poisoning.
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Affiliation(s)
- Sylvia Wagner
- Department of Cell Biology and Applied Virology, Fraunhofer Institute for Biomedical Engineering, Sankt Ingbert, Germany
| | - Jürgen Kufleitner
- Institute of Pharmaceutical Technology, Goethe-University, Frankfurt am Main, Germany
| | - Anja Zensi
- Institute of Pharmaceutical Technology, Goethe-University, Frankfurt am Main, Germany
| | - Miriam Dadparvar
- Institute of Pharmaceutical Technology, Goethe-University, Frankfurt am Main, Germany
| | - Sascha Wien
- Department of Cell Biology and Applied Virology, Fraunhofer Institute for Biomedical Engineering, Sankt Ingbert, Germany
| | - Judith Bungert
- Department of Cell Biology and Applied Virology, Fraunhofer Institute for Biomedical Engineering, Sankt Ingbert, Germany
| | | | - Franz Worek
- Bundeswehr Institute of Pharmacology und Toxicology, München, Germany
| | - Jörg Kreuter
- Institute of Pharmaceutical Technology, Goethe-University, Frankfurt am Main, Germany
| | - Hagen von Briesen
- Department of Cell Biology and Applied Virology, Fraunhofer Institute for Biomedical Engineering, Sankt Ingbert, Germany
- * E-mail:
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Basova NE, Rozengrart EV. [How the various substrates activate the process of enzymatic hydrolysis by different cholinesterases]. Zh Evol Biokhim Fiziol 2010; 46:485-488. [PMID: 21268878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Kinetic analysis of the activating effect of substrate on the cholinesterase catalysis is performed. There are determined values of coefficient of activation A in the pH zone 5.0-7.5 for the process of hydrolysis of acetylcholine, indophenylacetate (IPA), and 2,6-dichlorophenolindophenylacetate (DIPA) by cholinesterase (ChE) of horse blood serum, as well as of IPA and DIPA by ChE of optical ganglia of the Pacific squid Todarodes pacificus. The phenomenon of activation has not been revealed at hydrolysis of phenylacetate by the horse blood serum ChE. The conclusion is made that the cause of the activating effect of substrate on the process of enzymatic hydrolysis by ChEs of different origin is the presence of the onium grouping in the structure of substrates.
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Suga H, Sawyer GW, Ehlert FJ. Mutagenesis of nucleophilic residues near the orthosteric binding pocket of M1 and M2 muscarinic receptors: effect on the binding of nitrogen mustard analogs of acetylcholine and McN-A-343. Mol Pharmacol 2010; 78:745-55. [PMID: 20643905 PMCID: PMC2981396 DOI: 10.1124/mol.110.065367] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 07/19/2010] [Indexed: 11/22/2022] Open
Abstract
Investigating how a test drug alters the reaction of a site-directed electrophile with a receptor is a powerful method for determining whether the drug acts competitively or allosterically, provided that the binding site of the electrophile is known. In this study, therefore, we mutated nucleophilic residues near and within the orthosteric pockets of M(1) and M(2) muscarinic receptors to identify where acetylcholine mustard and 4-[(2-bromoethyl)methyl-amino]-2-butynyl-N-(3-chlorophenyl)carbamate (BR384) bind covalently. BR384 is the nitrogen mustard analog of [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride (McN-A-343). Mutation of the highly conserved aspartic acid in M(1) (Asp105) and M(2) (Asp103) receptors to asparagine largely prevented receptor alkylation by acetylcholine mustard, although modest alkylation still occurred at M(2) D103N at high concentrations of the mustard. Receptor alkylation by BR384 was also greatly inhibited in the M(1) D105N mutant, but some alkylation still occurred at high concentrations of the compound. In contrast, BR384 rapidly alkylated the M(2) D103N mutant. Its affinity was reduced to one tenth, however. The alkylation of M(2) D103N by BR384 was competitively inhibited by N-methylscopolamine and allosterically inhibited by gallamine. Mutation of a variety of other nucleophilic residues, some in combination with D103N, had little effect on M(2) receptor alkylation by BR384. Our results suggest that BR384 alkylates at least one residue other than the conserved aspartic acid at the ligand-binding site of M(1) and M(2) receptors. This additional residue seems to be located within or near the orthosteric-binding pocket and is not part of the allosteric site for gallamine.
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Affiliation(s)
- Hinako Suga
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA 92697-4625, USA
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Pei J, Li Q, Kennedy RT. Rapid and label-free screening of enzyme inhibitors using segmented flow electrospray ionization mass spectrometry. J Am Soc Mass Spectrom 2010; 21:1107-1113. [PMID: 20219390 DOI: 10.1016/j.jasms.2010.02.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 02/05/2010] [Accepted: 02/07/2010] [Indexed: 05/28/2023]
Abstract
Electrospray ionization mass spectrometry (ESI-MS) is an attractive analytical tool for high-throughput screening because of its rapid scan time and ability to detect compounds without need for labels. Impediments to the use of ESI-MS for screening have been the relatively large sample consumed and slow sample introduction rates associated with commonly used flow injection analysis. We have previously shown that by segmenting nanoliter plugs of sample with air, an array of discrete samples can be delivered to a platinum-coated emitter tip for ESI-MS analysis with throughput as high as 0.8 Hz and carry-over between samples less than 0.1%. This method was applied to screening for inhibitors of acetylcholinesterase as a demonstration of the potential of segmented flow ESI-MS for such applications. Each enzyme assay consumed 10 nL of sample. At 1 microL/min infusion rate, 102 samples were analyzed, corresponding to a 0.65 Hz sample analysis rate. Linear quantification of choline was achieved from 200 microM to 10 mM using this method and Z' values were over 0.8 for the assay. Detailed pharmacologic dose-response curves of selected inhibitors were also measured in high-throughput fashion to validate the method.
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Affiliation(s)
- Jian Pei
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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