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Wu H, Chen QX, Su Y, Chen Z. The Role of Hydrogen Bonds in Thermally Responsive Crystallization-Driven Template Autocatalysis. Angew Chem Int Ed Engl 2024:e202404838. [PMID: 38654551 DOI: 10.1002/anie.202404838] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 04/26/2024]
Abstract
Autocatalysis has been well recognized to implicate in the emergence of life and is intrinsic to the biomolecular replication. Recently, an efficient template autocatalysis driven by solvent-free crystallization has been reported. Herein, we unveil the role of intermolecular hydrogen (H) bonds formed by amides in crystallization-driven template autocatalysis (CDTA), which involves the autocatalytic activity, template selectivity, and thermal responsiveness. We found that the thermal-induced cis-trans isomerization of amides possibly affects the H-bonding-mediated template ability of products for autocatalytic transformation. As a result, CDTA can be reversibly inhibited and activated by tuning the reaction temperatures. Our work sheds light on the significance of noncovalent H-bonding interactions in artificial self-replicators.
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Affiliation(s)
- Huimin Wu
- Tsinghua Shenzhen International Graduate School, Institute of Materials Research, CHINA
| | - Qing-Xuan Chen
- Tsinghua Shenzhen International Graduate School, Institute of Materials Research, CHINA
| | - Yang Su
- Tsinghua Shenzhen International Graduate School, Institute of Materials Research, Shen Zhen, CHINA
| | - Zhen Chen
- Tsinghua Shenzhen International Graduate School, Institue of materials Research, University town of Shenzhen, Nanshan district, 518055, Shenzhen, CHINA
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2
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Yin Q, Chen G, Mu D, Yang Y, Hao J, Lin B, Zhou D, Hou Y, Li N. Natural anti-neuroinflammatory inhibitors in vitro and in vivo from Aglaia odorata. Bioorg Chem 2024; 147:107335. [PMID: 38583250 DOI: 10.1016/j.bioorg.2024.107335] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 03/24/2024] [Accepted: 04/03/2024] [Indexed: 04/09/2024]
Abstract
Fifty compounds including seven undescribed (1, 13, 18-20, 30, 31) and forty-three known (2-12, 14-17, 21-29, 32-50) ones were isolated from the extract of the twigs and leaves of Aglaia odorata with anti-neuroinflammatory activities. Their structures were determined by a combination of spectral analysis and calculated spectra (ECD and NMR). Among them, compounds 13-25 were found to possess tertiary amide bonds, with compounds 16, 17, and 19-21 existing detectable cis/trans mixtures in 1H NMR spectrum measured in CDCl3. Specifically, the analysis of the cis-trans isomerization equilibrium of tertiary amides in compounds 19-24 was conducted using NMR spectroscopy and quantum chemical calculations. Bioactivity evaluation showed that the cyclopenta[b]benzofuran derivatives (2-6, 8, 10, 12) could inhibit nitric oxide production at the nanomolar concentration (IC50 values ranging from 2 to 100 nM) in lipopolysaccharide-induced BV-2 cells, which were 413-20670 times greater than that of the positive drug (minocycline, IC50 = 41.34 μM). The cyclopenta[bc]benzopyran derivatives (13-16), diterpenoids (30-35), lignan (40), and flavonoids (45, 47, 49, 50) also demonstrated significant inhibitory activities with IC50 values ranging from 1.74 to 38.44 μM. Furthermore, the in vivo anti-neuroinflammatory effect of rocaglaol (12) was evaluated via immunofluorescence, qRT-PCR, and western blot assays in the LPS-treated mice model. The results showed that rocaglaol (12) attenuated the activation of microglia and decreased the mRNA expression of iNOS, TNF-α, IL-1β, and IL-6 in the cortex and hippocampus of mice. The mechanistic study suggested that rocaglaol might inhibit the activation of the NF-κB signaling pathway to relieve the neuroinflammatory response.
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Affiliation(s)
- Qianqian Yin
- School of Traditional Chinese Materia Medica, Key Laboratory of Innovative Traditional Chinese Medicine for Major Chronic Diseases of Liaoning province, Key Laboratory for TCM Material Basis Study and Innovative Drug Development of Shenyang City, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Gang Chen
- School of Traditional Chinese Materia Medica, Key Laboratory of Innovative Traditional Chinese Medicine for Major Chronic Diseases of Liaoning province, Key Laboratory for TCM Material Basis Study and Innovative Drug Development of Shenyang City, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Danyang Mu
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, National Frontiers Science Center for Industrial Intelligence and Systems Optimization, Key Laboratory of Data Analytics and Optimization for Smart Industry, Ministry of Education, Northeastern University, Shenyang 110167, China
| | - Yuxin Yang
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, National Frontiers Science Center for Industrial Intelligence and Systems Optimization, Key Laboratory of Data Analytics and Optimization for Smart Industry, Ministry of Education, Northeastern University, Shenyang 110167, China
| | - Jinle Hao
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Bin Lin
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Di Zhou
- School of Traditional Chinese Materia Medica, Key Laboratory of Innovative Traditional Chinese Medicine for Major Chronic Diseases of Liaoning province, Key Laboratory for TCM Material Basis Study and Innovative Drug Development of Shenyang City, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yue Hou
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, National Frontiers Science Center for Industrial Intelligence and Systems Optimization, Key Laboratory of Data Analytics and Optimization for Smart Industry, Ministry of Education, Northeastern University, Shenyang 110167, China.
| | - Ning Li
- School of Traditional Chinese Materia Medica, Key Laboratory of Innovative Traditional Chinese Medicine for Major Chronic Diseases of Liaoning province, Key Laboratory for TCM Material Basis Study and Innovative Drug Development of Shenyang City, Shenyang Pharmaceutical University, Shenyang 110016, China.
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Anshulata, Vishnoi P, Kanta Sarma B. Conformational Studies of β-Azapeptoid Foldamers: A New Class of Peptidomimetics with Confined Dihedrals. Chemistry 2024; 30:e202303330. [PMID: 37948294 DOI: 10.1002/chem.202303330] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/01/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
Controlling amide bond geometries and the secondary structures of β-peptoids is a challenging task as they contain several rotatable single bonds in their backbone. Herein, we describe the synthesis and conformational properties of novel "β-azapeptoids" with confined dihedrals. We discuss how the acylhydrazide sidechains in these molecules enforce trans amide geometries (ω ~180°) via steric and stereoelectronic effects. We also show that the Θ(Cα -Cβ ) and Ψ(OC-Cα ) backbone torsions of β-azapeptoids occupy a narrow range (170-180°) that can be rationalized by the staggered conformational preference of the backbone methylene carbons and a novel backbone nO →σ*Cβ-N interaction discovered in this study. However, the ϕ (Cβ -N) torsion remains freely rotatable and, depending on ϕ, the sidechains can be parallel, perpendicular, and anti-parallel relative to each other. In fact, we observed parallel and perpendicular relative orientations of sidechains in the crystal geometries of β-azapeptoid dimers. We show that ϕ of β-azapeptoids can be controlled by incorporating a bulky substituent at the backbone β-carbon, which could provide complete control over all the backbone dihedrals. Finally, we show that the ϕ and Ψ dihedrals of β-azapeptoids resemble that of a PPII helix and they retain PPII structure when incorporated in Host-guest proline peptides.
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Affiliation(s)
- Anshulata
- New Chemistry Unit (NCU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru, KA-560064, India
| | - Pratap Vishnoi
- New Chemistry Unit (NCU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru, KA-560064, India
| | - Bani Kanta Sarma
- New Chemistry Unit (NCU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru, KA-560064, India
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Minnullina GA, Efimov SV, Klochkov VV. Cis-trans isomerization in cyclosporin C dissolved in acetonitrile. Biochem Biophys Res Commun 2023; 683:149102. [PMID: 37857163 DOI: 10.1016/j.bbrc.2023.10.034] [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: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 10/21/2023]
Abstract
Cyclosporin is an 11-amino acid cyclic peptide with pharmacologically valuable properties which has a variety of actual and potential applications. Its activity relies on the cell membrane permeability which, in turn, depends on the structure of cyclosporin and its ability to change the conformation. In this work, conformational exchange processes occurring in cyclosporin C were studied using one- and two-dimensional nuclear magnetic resonance spectroscopy. The free energy barrier separating two major conformers observed in polar solution (acetonitrile) was found to be 77 ± 2 kJ/mol. Less populated conformation states are also present in the solution, which agrees with the ease of formation of multiple forms revealed by MD simulations of cyclosporin C.
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Affiliation(s)
- G A Minnullina
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan, 420008, Russia.
| | - S V Efimov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan, 420008, Russia
| | - V V Klochkov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan, 420008, Russia
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Chen XR, Igumenova TI. Regulation of eukaryotic protein kinases by Pin1, a peptidyl-prolyl isomerase. Adv Biol Regul 2023; 87:100938. [PMID: 36496344 PMCID: PMC9992314 DOI: 10.1016/j.jbior.2022.100938] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022]
Abstract
The peptidyl-prolyl isomerase Pin1 cooperates with proline-directed kinases and phosphatases to regulate multiple oncogenic pathways. Pin1 specifically recognizes phosphorylated Ser/Thr-Pro motifs in proteins and catalyzes their cis-trans isomerization. The Pin1-catalyzed conformational changes determine the stability, activity, and subcellular localization of numerous protein substrates. We conducted a survey of eukaryotic protein kinases that are regulated by Pin1 and whose Pin1 binding sites have been identified. Our analyses reveal that Pin1 target sites in kinases do not fall exclusively within the intrinsically disordered regions of these enzymes. Rather, they fall into three groups based on their location: (i) within the catalytic kinase domain, (ii) in the C-terminal kinase region, and (iii) in regulatory domains. Some of the kinases downregulated by Pin1 activity are tumor-suppressing, and all kinases upregulated by Pin1 activity are functionally pro-oncogenic. These findings further reinforce the rationale for developing Pin1-specific inhibitors as attractive pharmaceuticals for cancer therapy.
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Affiliation(s)
- Xiao-Ru Chen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Tatyana I Igumenova
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA.
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Akbari V, Mohammadi S, Mehrabi M, Ghobadi S, Farrokhi A, Khodarahmi R. Investigation of the role of prolines 232/233 in RTPPK motif in tau protein aggregation: An in vitro study. Int J Biol Macromol 2022; 219:1100-1111. [PMID: 36049563 DOI: 10.1016/j.ijbiomac.2022.08.160] [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: 02/17/2022] [Revised: 07/26/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022]
Abstract
Disease-related tau protein in Alzheimer's disease is hyperphosphorylated and aggregates into neurofibrillary tangles. The cis-proline isomer of the pSer/Thr-Pro sequence has been proposed to act as a precursor of aggregation ('Cistauosis' hypothesis), but this aggregation scheme is not yet entirely accepted. Hence to investigate isomer-specific-aggregation of tau, proline residues at the RTPPK motif were replaced by alanine residues (with permanent trans configuration) employing genetic engineering methods. RTPAK, RTAPK, and RTAAK mutant variants of tau were generated, and their in vitro aggregation propensity was investigated using multi-spectroscopic techniques. Besides, the cell toxicity of oligomers/fibrils was analyzed and compared to those of the wild-type (WT) tau. Analyses of mutant variants have shown to be in agreement (to some degree) to the theory of the 'cistauosis' hypothesis. The results showed that the trans isomer in the 232-rd residue (P232A mutant rather than P233A) had reduced aggregation propensity. However, this study did not illustrate any statistically significant difference between the wild and the mutant protein aggregations concerning cell toxicity.
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Affiliation(s)
- Vali Akbari
- Department of Biology, Faculty of Sciences, Razi University, Kermanshah, Iran; Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences (KUMS), Kermanshah, Iran
| | - Soheila Mohammadi
- Nano Drug Delivery Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Masomeh Mehrabi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences (KUMS), Kermanshah, Iran
| | - Sirous Ghobadi
- Department of Biology, Faculty of Sciences, Razi University, Kermanshah, Iran.
| | - Alireza Farrokhi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences (KUMS), Kermanshah, Iran
| | - Reza Khodarahmi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences (KUMS), Kermanshah, Iran; Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Kermanshah University of Medical Sciences (KUMS), Kermanshah, Iran.
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Olsztyńska-Janus S, Czarnecki MA. Effect of elevated temperature and UV radiation on molecular structure of linoleic acid by ATR-IR and two-dimensional correlation spectroscopy. Spectrochim Acta A Mol Biomol Spectrosc 2020; 238:118436. [PMID: 32403075 DOI: 10.1016/j.saa.2020.118436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 01/31/2020] [Revised: 04/17/2020] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
The effect of elevated temperature (44 °C) and ultraviolet (UV) radiation on molecular structure of linoleic acid (LA) was studied by Attenuated Total Reflection Infrared (ATR-IR) spectroscopy. To obtain more detailed information on molecular mechanism of these changes we applied moving-window analysis and two-dimensional correlation spectroscopy (2DCOS). Analysis of the time-dependent ATR-IR spectra of LA before and after UV irradiation revealed the structural changes in molecules of LA. The extent of these changes was significantly higher after an application of UV radiation. During 24 h experiment temperature was constant, therefore the spectral changes result from relatively slow processes (and requiring more energy), e.g. cis/trans isomerization, disruption of the C=C double bonds and partial breaking of hydrogen bonds in the cyclic dimers. As a side effect of these structural changes one can observe variations in the orientation of the chains. It is of note that the methyl and methylene groups reveal slightly different behaviour.
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Affiliation(s)
- S Olsztyńska-Janus
- Department of Biomedical Engineering, Wrocław University of Science and Technology, pl. Grunwaldzki 13, 50-370 Wrocław, Poland.
| | - M A Czarnecki
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
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Teplyakov A, Obmolova G, Gilliland GL. Structural insights into chemokine CCL17 recognition by antibody M116. Biochem Biophys Rep 2017; 13:27-31. [PMID: 29264403 PMCID: PMC5726885 DOI: 10.1016/j.bbrep.2017.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 12/21/2022] Open
Abstract
The homeostatic chemokine CCL17, also known as thymus and activation regulated chemokine (TARC), has been associated with various diseases such as asthma, idiopathic pulmonary fibrosis, atopic dermatitis and ulcerative colitis. Neutralization of CCL17 by antibody treatment ameliorates the impact of disease by blocking influx of T cells. Monoclonal antibody M116 derived from a combinatorial library shows potency in neutralizing CCL17-induced signaling. To gain insight into the structural determinants of antigen recognition, the crystal structure of M116 Fab was determined in complex with CCL17 and in the unbound form. Comparison of the structures revealed an unusual induced-fit mechanism of antigen recognition that involves cis-trans isomerization in two CDRs. The structure of the CCL17-M116 complex revealed the antibody binding epitope, which does not overlap with the putative receptor epitope, suggesting that the current model of chemokine-receptor interactions, as observed in the CXCR4-vMIP-II system, may not be universal.
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Key Words
- Antibody
- CCL17
- CDR, complementarity determining region
- Cis-trans isomerization
- Crystal structure
- DTT, dithiothreitol
- EDTA, ethylenediaminetetraacetic acid
- Epitope
- HEPES, 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid
- Neutralization
- PDB, Protein Data Bank
- PEG, polyethylene glycol
- RMSD, root-mean-square deviation
- VH, variable domain of the heavy chain
- VL, variable domain of the light chain
- mAb, monoclonal antibody
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Affiliation(s)
- Alexey Teplyakov
- Janssen Research and Development, LLC, Spring House, PA 19477, USA
| | - Galina Obmolova
- Janssen Research and Development, LLC, Spring House, PA 19477, USA
| | - Gary L Gilliland
- Janssen Research and Development, LLC, Spring House, PA 19477, USA
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An B, Yuan H, Zhu Q, Li Y, Guo X, Zhang J. Theoretical insight into the excited-state intramolecular proton transfer mechanisms of three amino-type hydrogen-bonding molecules. Spectrochim Acta A Mol Biomol Spectrosc 2017; 175:36-42. [PMID: 28012390 DOI: 10.1016/j.saa.2016.12.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
Excited-state intramolecular proton transfer (ESIPT) dynamics of the amino-type hydrogen-bonding compound 2-(2'-aminophenyl)benzothiazole (PBT-NH2) as well as its two derivatives 2-(5'-cyano-2'-aminophenyl)benzothiazole (CN-PBT-NH2) and 2-(5'-cyano-2'-tosylaminophenyl)benzothiazole (CN-PBT-NHTs) were studied by the time-dependent density functional theory (TD-DFT) approach with the B3LYP density functional, and their absorption and emission spectra were also explored at the same level of theory. A good agreement is observed between the theoretical simulations and experimental spectra, indicating that the present calculations are reasonably reliable. In addition, it is also found that the energy barriers of the first excited singlet state of the three targeted molecules along the ESIPT reaction are computed to be 0.38, 0.34 and 0.12eV, respectively, showing the trend of gradual decrease, which implies that the introduction of the electron-withdrawing cyano or tosyl group can facilitate the occurrence of the ESIPT reaction of these amino-type H-bonding systems. Following the ESIPT, both CN-PBT-NH2 and CN-PBT-NHTs dye molecules can undergo the cis-trans isomerization reactions in the ground-state and excited-state potential energy curves along the C2-C3 bond between benzothiazole and phenyl moieties, where the energy barriers of the trans-tautomer→cis-tautomer isomerizations in the ground states are calculated to be 0.83 and 0.34eV, respectively. According to our calculations, it is plausible that there may exist the long-lived trans-tautomer species in the ground states of CN-PBT-NH2 and CN-PBT-NHTs.
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Affiliation(s)
- Beibei An
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China
| | - Huijuan Yuan
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China
| | - Qiuling Zhu
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China
| | - Yuanyuan Li
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China
| | - Xugeng Guo
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China.
| | - Jinglai Zhang
- Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People's Republic of China.
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Fuller DR, Glover MS, Pierson NA, Kim D, Russell DH, Clemmer DE. Cis→Trans Isomerization of Pro(7) in Oxytocin Regulates Zn(2+) Binding. J Am Soc Mass Spectrom 2016; 27:1376-82. [PMID: 27154022 PMCID: PMC5161230 DOI: 10.1007/s13361-016-1410-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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] [Received: 03/09/2016] [Revised: 04/11/2016] [Accepted: 04/14/2016] [Indexed: 05/28/2023]
Abstract
Ion mobility/mass spectrometry techniques are employed to investigate the binding of Zn(2+) to the nine-residue peptide hormone oxytocin (OT, Cys(1)-Tyr(2)-Ile(3)-Gln(4)-Asn(5)-Cys(6)-Pro(7)-Leu(8)-Gly(9)-NH2, having a disulfide bond between Cys(1) and Cys(6) residues). Zn(2+) binding to OT is known to increase the affinity of OT for its receptor [Pearlmutter, A. F., Soloff, M. S.: Characterization of the metal ion requirement for oxytocin-receptor interaction in rat mammary gland membranes. J. Biol. Chem. 254, 3899-3906 (1979)]. In the absence of Zn(2+), we find evidence for two primary OT conformations, which arise because the Cys(6)-Pro(7) peptide bond exists in both the trans- and cis-configurations. Upon addition of Zn(2+), we determine binding constants in water of KA = 1.43 ± 0.24 and 0.42 ± 0.12 μM(-1), for the trans- and cis-configured populations, respectively. The Zn(2+) bound form of OT, having a cross section of Ω = 235 Å(2), has Pro(7) in the trans-configuration, which agrees with a prior report [Wyttenbach, T., Liu, D., Bowers, M. T.: Interactions of the hormone oxytocin with divalent metal ions. J. Am. Chem. Soc. 130, 5993-6000 (2008)], in which it was proposed that Zn(2+) binds to the peptide ring and is further coordinated by interaction of the C-terminal, Pro(7)-Leu(8)-Gly(9)-NH2, tail. The present work shows that the cis-configuration of OT isomerizes to the trans-configuration upon binding Zn(2+). In this way, the proline residue regulates Zn(2+) binding to OT and, hence, is important in receptor binding. Graphical Abstract ᅟ.
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Affiliation(s)
- Daniel R Fuller
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Matthew S Glover
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Nicholas A Pierson
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
- Merck Research Laboratories, Rahway, NJ, 07065, USA
| | - DoYong Kim
- Department of Chemistry, Texas A&M University, College Station, TX, 77842, USA
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, TX, 77842, USA
| | - David E Clemmer
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
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Yuvaraj AR, Yam WS, Chan TN, Goh YP, Hegde G. New para-substituted non-symmetric isoflavones for their fast photo-switching ability: synthesis and their liquid crystal characterization. Spectrochim Acta A Mol Biomol Spectrosc 2015; 135:1115-1122. [PMID: 25173529 DOI: 10.1016/j.saa.2014.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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: 06/12/2014] [Revised: 08/01/2014] [Accepted: 08/05/2014] [Indexed: 06/03/2023]
Abstract
The first example of non-symmetric isoflavone-based fast photo-switchable liquid crystals with different functional groups at the terminal position were synthesized and characterized. Polarizing optical microscopy study revealed that the compounds showed least ordered nematic phase. Optical photo switching study exhibited very fast photoisomerization effect in solution. The E-Z and Z-E conversion occurred around 3-5s and 40-700 s respectively. This is also the first example of para-substituted non-symmetric isoflavone liquid crystals exhibiting very fast photo switching property in solution. Argument based on non-symmetrical behaviour might be the reason for the observed behaviour.
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Affiliation(s)
- A R Yuvaraj
- Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Gambang, Kuantan, Malaysia
| | - Wan Sinn Yam
- School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Tze Nee Chan
- School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Yit Peng Goh
- School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Gurumurthy Hegde
- Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Gambang, Kuantan, Malaysia.
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