1
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Hrvat NM, Kovarik Z. Counteracting poisoning with chemical warfare nerve agents. Arh Hig Rada Toksikol 2020; 71:266-284. [PMID: 33410774 PMCID: PMC7968514 DOI: 10.2478/aiht-2020-71-3459] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/01/2020] [Accepted: 11/01/2020] [Indexed: 12/14/2022] Open
Abstract
Phosphylation of the pivotal enzyme acetylcholinesterase (AChE) by nerve agents (NAs) leads to irreversible inhibition of the enzyme and accumulation of neurotransmitter acetylcholine, which induces cholinergic crisis, that is, overstimulation of muscarinic and nicotinic membrane receptors in the central and peripheral nervous system. In severe cases, subsequent desensitisation of the receptors results in hypoxia, vasodepression, and respiratory arrest, followed by death. Prompt action is therefore critical to improve the chances of victim's survival and recovery. Standard therapy of NA poisoning generally involves administration of anticholinergic atropine and an oxime reactivator of phosphylated AChE. Anticholinesterase compounds or NA bioscavengers can also be applied to preserve native AChE from inhibition. With this review of 70 years of research we aim to present current and potential approaches to counteracting NA poisoning.
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Affiliation(s)
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
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2
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Palikov VA, Palikova YA, Dyachenko IA. Study of protective properties of butyrylcholinesterase in acute anticholinesterase poisoning on BChE-KO and BALB/c mice. RESEARCH RESULTS IN PHARMACOLOGY 2020. [DOI: 10.3897/rrpharmacology.6.50941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: The article presents the results of studying the protective properties of recombinant human butyrylcholinesterase (rhBChE) in a model of acute anticholinesterase poisoning in mice knocked out for the BChE gene. Balb/c inbred mice were also used to demonstrate the important role of BChE.Materials and methods: In the study, BChE-ko and Balb/c mice were used. An organophosphorus compound (OPC) paraoxon was used as a toxic agent causing acute anticholinesterase poisoning. rhBChE was used as an antidote for OPC poisoning. To obtain rhBChE, an expression system based on CHO cell lines was chosen. In order to suppress BChE in Balb/c mice, a carboxyl esterase blocker cresylbenzodioxaphosphorin oxide (CBDP) was used. Two parameters were used to study the recovery after toxicity modeling: the end time of the animal tremor and the distance covered in open-field for 3 minutes.Results and discussion: The acute poisoning model using the CBDP blocker showed that the sensitivity of Balb/c mice increased significantly. The use of rhBChE against the background of CBDP allowed achieving 100% survival of animals with the minimum lethal dose of paraoxon. Knockout mice are expected to be more sensitive to the toxin, and the use of a biological trap in the form of rhBChE made it possible for 70% of the animals to survive with the minimum lethal dose of paraoxon. Besides, the use of rhBChE facilitated reducing the recovery time after OPC poisoning.Conclusion: The results of the study showed that the use of rhBChE as a protective agent in acute OPC poisoning significantly increased the survival of the animals and reduced the clinical manifestations of poisoning.
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Zueva IV, Lushchekina SV, Daudé D, Chabrière E, Masson P. Steady-State Kinetics of Enzyme-Catalyzed Hydrolysis of Echothiophate, a P-S Bonded Organophosphorus as Monitored by Spectrofluorimetry. Molecules 2020; 25:molecules25061371. [PMID: 32192230 PMCID: PMC7144395 DOI: 10.3390/molecules25061371] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 02/02/2023] Open
Abstract
Enzyme-catalyzed hydrolysis of echothiophate, a P–S bonded organophosphorus (OP) model, was spectrofluorimetrically monitored, using Calbiochem Probe IV as the thiol reagent. OP hydrolases were: the G117H mutant of human butyrylcholinesterase capable of hydrolyzing OPs, and a multiple mutant of Brevundimonas diminuta phosphotriesterase, GG1, designed to hydrolyze a large spectrum of OPs at high rate, including V agents. Molecular modeling of interaction between Probe IV and OP hydrolases (G117H butyrylcholinesterase, GG1, wild types of Brevundimonas diminuta and Sulfolobus solfataricus phosphotriesterases, and human paraoxonase-1) was performed. The high sensitivity of the method allowed steady-state kinetic analysis of echothiophate hydrolysis by highly purified G117H butyrylcholinesterase concentration as low as 0.85 nM. Hydrolysis was michaelian with Km = 0.20 ± 0.03 mM and kcat = 5.4 ± 1.6 min−1. The GG1 phosphotriesterase hydrolyzed echothiophate with a high efficiency (Km = 2.6 ± 0.2 mM; kcat = 53400 min−1). With a kcat/Km = (2.6 ± 1.6) × 107 M−1min−1, GG1 fulfills the required condition of potential catalytic bioscavengers. quantum mechanics/molecular mechanics (QM/MM) and molecular docking indicate that Probe IV does not interact significantly with the selected phosphotriesterases. Moreover, results on G117H mutant show that Probe IV does not inhibit butyrylcholinesterase. Therefore, Probe IV can be recommended for monitoring hydrolysis of P–S bonded OPs by thiol-free OP hydrolases.
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Affiliation(s)
- Irina V. Zueva
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, Arbuzov str. 8, 420088 Kazan, Russia;
| | - Sofya V. Lushchekina
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin str 4, 119334 Moscow, Russia;
| | - David Daudé
- Gene&GreenTK, HU Méditerranée Infection, Jean Moulin Blvd 19–21, 13005 Marseille, France;
| | - Eric Chabrière
- Aix-Marseille University, IRD, APHM, MEPHI, IHU-Méditerranée Infection, 15005 Marseille, France;
| | - Patrick Masson
- Kazan Federal University, Neuropharmacology Laboratory, Kremlevskaya str 18, 480002 Kazan, Russia
- Correspondence: ; Tel.: +7-96-5581-0473
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4
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Grigorenko BL, Novichkova DA, Lushchekina SV, Zueva IV, Schopfer LM, Nemukhin AV, Varfolomeev SD, Lockridge O, Masson P. Computer-designed active human butyrylcholinesterase double mutant with a new catalytic triad. Chem Biol Interact 2019; 306:138-146. [PMID: 31009643 DOI: 10.1016/j.cbi.2019.04.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 04/04/2019] [Accepted: 04/15/2019] [Indexed: 01/05/2023]
Abstract
A computer-designed mutant of human butyrylcholinesterase (BChE), N322E/E325G, with a novel catalytic triad was made. The catalytic triad of the wild-type enzyme (S198·H438·E325) was replaced by S198·H438·N322E in silico. Molecular dynamics for 1.5 μs and Markov state model analysis showed that the new catalytic triad should be operative in the mutant enzyme, suggesting functionality. QM/MM modeling performed for the reaction of wild-type BChE and double mutant with echothiophate showed high reactivity of the mutant towards the organophosphate. A truncated monomeric (L530 stop) double mutant was expressed in Expi293 cells. Non-purified transfected cell culture medium was analyzed. Polyacrylamide gel electrophoresis under native conditions followed by activity staining with BTC as the substrate provided evidence that the monomeric BChE mutant was active. Inhibition of the double mutant by echothiophate followed by polyacrylamide gel electrophoresis and activity staining showed that this enzyme slowly self-reactivated. However, because Expi293 cells secrete an endogenous BChE tetramer and several organophosphate-reacting enzymes, catalytic parameters and self-reactivation constants after phosphorylation of the new mutant were not determined in the crude cell culture medium. The study shows that the computer-designed double mutant (N322E/E325G) with a new catalytic triad (S198·H438·N322E) is a suitable template for design of novel active human BChE mutants that display an organophosphate hydrolase activity.
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Affiliation(s)
- Bella L Grigorenko
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygina Str. 4, Moscow 119334, Russia; Lomonosov State University, Chemistry Department, Moscow 119991, Russia
| | - Dana A Novichkova
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygina Str. 4, Moscow 119334, Russia
| | - Sofya V Lushchekina
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygina Str. 4, Moscow 119334, Russia.
| | - Irina V Zueva
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov Str. 8, Kazan, 420088, Russia; Kazan Federal University, Neuropharmacology Laboratory, Kremlevskaya Str, 18, Kazan, 420008, Russia
| | - Lawrence M Schopfer
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Alexander V Nemukhin
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygina Str. 4, Moscow 119334, Russia; Lomonosov State University, Chemistry Department, Moscow 119991, Russia
| | - Sergey D Varfolomeev
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygina Str. 4, Moscow 119334, Russia; Lomonosov State University, Chemistry Department, Moscow 119991, Russia
| | - Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Patrick Masson
- Kazan Federal University, Neuropharmacology Laboratory, Kremlevskaya Str, 18, Kazan, 420008, Russia.
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5
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Lushchekina S, Masson P. Catalytic bioscavengers against organophosphorus agents: mechanistic issues of self-reactivating cholinesterases. Toxicology 2018; 409:91-102. [DOI: 10.1016/j.tox.2018.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 12/21/2022]
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6
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Lushchekina SV, Schopfer LM, Grigorenko BL, Nemukhin AV, Varfolomeev SD, Lockridge O, Masson P. Optimization of Cholinesterase-Based Catalytic Bioscavengers Against Organophosphorus Agents. Front Pharmacol 2018; 9:211. [PMID: 29593539 PMCID: PMC5859046 DOI: 10.3389/fphar.2018.00211] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 02/26/2018] [Indexed: 11/13/2022] Open
Abstract
Organophosphorus agents (OPs) are irreversible inhibitors of acetylcholinesterase (AChE). OP poisoning causes major cholinergic syndrome. Current medical counter-measures mitigate the acute effects but have limited action against OP-induced brain damage. Bioscavengers are appealing alternative therapeutic approach because they neutralize OPs in bloodstream before they reach physiological targets. First generation bioscavengers are stoichiometric bioscavengers. However, stoichiometric neutralization requires administration of huge doses of enzyme. Second generation bioscavengers are catalytic bioscavengers capable of detoxifying OPs with a turnover. High bimolecular rate constants (kcat/Km > 106 M−1min−1) are required, so that low enzyme doses can be administered. Cholinesterases (ChE) are attractive candidates because OPs are hemi-substrates. Moderate OP hydrolase (OPase) activity has been observed for certain natural ChEs and for G117H-based human BChE mutants made by site-directed mutagenesis. However, before mutated ChEs can become operational catalytic bioscavengers their dephosphylation rate constant must be increased by several orders of magnitude. New strategies for converting ChEs into fast OPase are based either on combinational approaches or on computer redesign of enzyme. The keystone for rational conversion of ChEs into OPases is to understand the reaction mechanisms with OPs. In the present work we propose that efficient OP hydrolysis can be achieved by re-designing the configuration of enzyme active center residues and by creating specific routes for attack of water molecules and proton transfer. Four directions for nucleophilic attack of water on phosphorus atom were defined. Changes must lead to a novel enzyme, wherein OP hydrolysis wins over competing aging reactions. Kinetic, crystallographic, and computational data have been accumulated that describe mechanisms of reactions involving ChEs. From these studies, it appears that introducing new groups that create a stable H-bonded network susceptible to activate and orient water molecule, stabilize transition states (TS), and intermediates may determine whether dephosphylation is favored over aging. Mutations on key residues (L286, F329, F398) were considered. QM/MM calculations suggest that mutation L286H combined to other mutations favors water attack from apical position. However, the aging reaction is competing. Axial direction of water attack is not favorable to aging. QM/MM calculation shows that F329H+F398H-based multiple mutants display favorable energy barrier for fast reactivation without aging.
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Affiliation(s)
- Sofya V Lushchekina
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia
| | - Lawrence M Schopfer
- Department of Biochemistry and Molecular Biology, Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Bella L Grigorenko
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Alexander V Nemukhin
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Sergei D Varfolomeev
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Oksana Lockridge
- Department of Biochemistry and Molecular Biology, Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Patrick Masson
- Neuropharmacology Laboratory, Kazan Federal University, Kazan, Russia
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7
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A Study of the Protective Properties of an Antibody-Based Antidote Metabolizing Organophosphorus Pesticide Paraoxon. Bull Exp Biol Med 2017; 163:218-221. [PMID: 28726199 DOI: 10.1007/s10517-017-3770-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Indexed: 10/19/2022]
Abstract
A catalytic antibody A17 and its mutants highly efficiently interact with organophosphorus pesticide paraoxon. In this work, we studied the protective properties of antibody A17-K47 in paraoxon poisoning using a mouse model. The optimal paraoxon dose simulating the acute toxic effect of organophosphorus compounds was 550 μg/kg. The pharmacokinetic parameters of A17-K47 antibody were t1/2distr =7.2±1.4 min, t1/2el =330±20 min. The antibody did not cause toxic effects when administered at a ten-fold calculated therapeutic dose (610 mg/kg). The drug did not reduce mortality from acute paraoxon poisoning; however, the absence of drug toxicity opens up prospects for its use in symptomatic treatment of chronic paraoxon poisoning.
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8
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Masson P, Nachon F. Cholinesterase reactivators and bioscavengers for pre- and post-exposure treatments of organophosphorus poisoning. J Neurochem 2017; 142 Suppl 2:26-40. [PMID: 28542985 DOI: 10.1111/jnc.14026] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/02/2017] [Accepted: 03/10/2017] [Indexed: 12/11/2022]
Abstract
Organophosphorus agents (OPs) irreversibly inhibit acetylcholinesterase (AChE) causing a major cholinergic syndrome. The medical counter-measures of OP poisoning have not evolved for the last 30 years with carbamates for pretreatment, pyridinium oximes-based AChE reactivators, antimuscarinic drugs and neuroprotective benzodiazepines for post-exposure treatment. These drugs ensure protection of peripheral nervous system and mitigate acute effects of OP lethal doses. However, they have significant limitations. Pyridostigmine and oximes do not protect/reactivate central AChE. Oximes poorly reactivate AChE inhibited by phosphoramidates. In addition, current neuroprotectants do not protect the central nervous system shortly after the onset of seizures when brain damage becomes irreversible. New therapeutic approaches for pre- and post-exposure treatments involve detoxification of OP molecules before they reach their molecular targets by administrating catalytic bioscavengers, among them phosphotriesterases are the most promising. Novel generation of broad spectrum reactivators are designed for crossing the blood-brain barrier and reactivate central AChE. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Patrick Masson
- Neuropharmacology Laboratory, Kazan Federal University, Kazan, Russia
| | - Florian Nachon
- Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, Cédex, France
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9
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Molecular polymorphism of human enzymes as the basis of individual sensitivity to drugs. Supercomputer-assisted modeling as a tool for analysis of structural changes and enzymatic activity of proteins. Russ Chem Bull 2017. [DOI: 10.1007/s11172-016-1487-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Masson P, Lushchekina SV. Emergence of catalytic bioscavengers against organophosphorus agents. Chem Biol Interact 2016; 259:319-326. [DOI: 10.1016/j.cbi.2016.02.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 12/16/2015] [Accepted: 02/10/2016] [Indexed: 02/05/2023]
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11
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Langston JL, Myers TM. VX toxicity in the Göttingen minipig. Toxicol Lett 2016; 264:12-19. [PMID: 27773723 DOI: 10.1016/j.toxlet.2016.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 09/20/2016] [Accepted: 10/19/2016] [Indexed: 11/18/2022]
Abstract
The present experiments determined the intramuscular LD50 of VX in male Göttingen minipigs at two stages of development. In pubertal animals (115 days old), the LD50 of VX was indeterminate, but approximated 33.3μg/kg. However, in sexually mature animals (152 days old), the LD50 was estimated to be only 17.4μg/kg. Signs of nerve agent toxicity in the Göttingen minipig were similar to those described for other species, with some notable exceptions (such as urticaria and ejaculation). Latencies to the onset of sustained convulsions were inversely related to the administered dose of VX in both ages of minipigs. Additionally, actigraphy was used to quantify the presence of tremor and convulsions and, in some cases, was useful for precisely estimating time of death. The main finding indicates that in minipigs, as in other species, even relatively small differences in age can substantially alter the toxicity of nerve agents. Additionally, actigraphy can serve as a non-invasive method of characterizing the tremors and convulsions that often accompany nerve agent intoxication.
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Affiliation(s)
- Jeffrey L Langston
- Analytical Toxicology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Todd M Myers
- Analytical Toxicology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA.
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12
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Masson P. Novel approaches in prophylaxis/pretreatment and treatment of organophosphorus poisoning. PHOSPHORUS SULFUR 2016. [DOI: 10.1080/10426507.2016.1211652] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Patrick Masson
- Neuropharmacology Laboratory, Kazan Federal University, Kazan, Russian Federation
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13
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Maraković N, Knežević A, Vinković V, Kovarik Z, Šinko G. Design and synthesis of N-substituted-2-hydroxyiminoacetamides and interactions with cholinesterases. Chem Biol Interact 2016; 259:122-132. [PMID: 27238725 DOI: 10.1016/j.cbi.2016.05.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 04/20/2016] [Accepted: 05/25/2016] [Indexed: 11/27/2022]
Abstract
Within this study, we designed and synthesized four new oxime compounds of the N-substituted 2-hydroxyiminoacetamide structure and evaluated their interactions with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Our aim was to explore the possibility of extending the dual-binding mode of interaction between the enzyme and the inhibitor to a so-called triple-binding mode of interaction through the introduction of an additional binding moiety. N-substituted 2-hydroxyiminoacetamide 1 was prepared via BOP catalyzed amidation of hydroxyiminoacetic acid with 3-azido-1-phenylpropylamine. An azide group enabled us to prepare more elaborate structures 2-4 by the copper-catalyzed azide-alkyne cycloaddition. The new compounds 1-4 differed in their presumed AChE peripheral site binding moiety, which ranged from an azide group to functionalized heterocycles. Molecular docking studies revealed that all three binding moieties are involved in the non-covalent interactions with ChEs for all of the four compounds, albeit not always in the complete accordance with the proposed hypothesis. All of the four compounds reversibly inhibited the ChEs with their inhibition potency increasing in the same order for both enzymes (1 < 2 < 4 < 3). A higher preference for binding to BChE (KI from 0.30 μmol/L to 130 μmol/L) over AChE (KI from 50 μmol/L to 1200 μmol/L) was observed for all of the compounds. Compounds were screened for reactivation of cyclosarin-, sarin- and VX-inhibited AChE and BChE.
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Affiliation(s)
- Nikola Maraković
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia
| | | | - Vladimir Vinković
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10 000 Zagreb, Croatia
| | - Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia
| | - Goran Šinko
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10 000 Zagreb, Croatia.
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Terekhov SS, Bobik TV, Mokrushina YA, Stepanova AV, Aleksandrova NM, Smirnov IV, Belogurov AA, Ponomarenko NA, Gabibov AG. Expression of DNA-Encoded Antidote to Organophosphorus Toxins in the Methylotrophic Yeast Pichia Pastoris. APPL BIOCHEM MICRO+ 2016. [DOI: 10.1134/s0003683816020162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Terekhov S, Smirnov I, Bobik T, Shamborant O, Zenkova M, Chernolovskaya E, Gladkikh D, Murashev A, Dyachenko I, Palikov V, Palikova Y, Knorre V, Belogurov A, Ponomarenko N, Blackburn GM, Masson P, Gabibov A. A novel expression cassette delivers efficient production of exclusively tetrameric human butyrylcholinesterase with improved pharmacokinetics for protection against organophosphate poisoning. Biochimie 2015; 118:51-9. [DOI: 10.1016/j.biochi.2015.07.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 07/30/2015] [Indexed: 10/23/2022]
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16
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Letort S, Mathiron D, Grel T, Albaret C, Daulon S, Djedaïni-Pilard F, Gouhier G, Estour F. The first 2(IB),3(IA)-heterodifunctionalized β-cyclodextrin derivatives as artificial enzymes. Chem Commun (Camb) 2015; 51:2601-4. [PMID: 25572650 DOI: 10.1039/c4cc09189b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Novel 2,3-heterodisubstituted β-cyclodextrin derivatives were designed as artificial enzymes to degrade chemical warfare agents. One of them reduced the acetylcholinesterase inhibitory potential by soman faster than its monosubstituted analog.
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Affiliation(s)
- S Letort
- Normandie Université, COBRA, UMR 6014 et FR 3038, Université de Rouen, INSA de Rouen, CNRS, 1 rue Tesnière, 76821 Mont-Saint-Aignan Cedex, France.
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17
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Katz FS, Pecic S, Tran TH, Trakht I, Schneider L, Zhu Z, Ton-That L, Luzac M, Zlatanic V, Damera S, Macdonald J, Landry DW, Tong L, Stojanovic MN. Discovery of New Classes of Compounds that Reactivate Acetylcholinesterase Inhibited by Organophosphates. Chembiochem 2015; 16:2205-2215. [PMID: 26350723 DOI: 10.1002/cbic.201500348] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Indexed: 11/11/2022]
Abstract
Acetylcholinesterase (AChE) that has been covalently inhibited by organophosphate compounds (OPCs), such as nerve agents and pesticides, has traditionally been reactivated by using nucleophilic oximes. There is, however, a clearly recognized need for new classes of compounds with the ability to reactivate inhibited AChE with improved in vivo efficacy. Here we describe our discovery of new functional groups--Mannich phenols and general bases--that are capable of reactivating OPC--inhibited AChE more efficiently than standard oximes and we describe the cooperative mechanism by which these functionalities are delivered to the active site. These discoveries, supported by preliminary in vivo results and crystallographic data, significantly broaden the available approaches for reactivation of AChE.
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Affiliation(s)
- Francine S Katz
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Stevan Pecic
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Timothy H Tran
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027 (USA)
| | - Ilya Trakht
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Laura Schneider
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Zhengxiang Zhu
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Long Ton-That
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Michal Luzac
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Viktor Zlatanic
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Shivani Damera
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Joanne Macdonald
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA).,Genecology Research Centre, Inflammation and Healing Research Cluster, School of Science and Engineering, University of the Sunshine Coast, 90 Sippy Downs Drive, Sippy Downs, QLD 4556 (Australia)
| | - Donald W Landry
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA)
| | - Liang Tong
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027 (USA)
| | - Milan N Stojanovic
- Department of Medicine/Division of Experimental Therapeutics, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032 (USA).,Departments of Biomedical Engineering and Systems Biology, Columbia University, 630 W. 168th street, New York, NY 10032 (USA)
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Chapleau RR, McElroy CA, Ruark CD, Fleming EJ, Ghering AB, Schlager JJ, Poeppelman LD, Gearhart JM. High-Throughput Screening for Positive Allosteric Modulators Identified Potential Therapeutics against Acetylcholinesterase Inhibition. JOURNAL OF BIOMOLECULAR SCREENING 2015; 20:1142-9. [PMID: 26078409 DOI: 10.1177/1087057115591006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 05/20/2015] [Indexed: 11/16/2022]
Abstract
The current standard of care for treatment of organophosphate (OP) poisoning includes pretreatment with the weak reversible acetylcholinesterase (AChE) inhibitor pyridostigmine bromide. Because this drug is an AChE inhibitor, similar side effects exist as with OP poisoning. In an attempt to provide a therapeutic capable of mitigating AChE inhibition without such side effects, high-throughput screening was performed to identify a compound capable of increasing the catalytic activity of AChE. Herein, two such novel positive allosteric modulators (PAMs) of AChE are presented. These PAMs increase AChE activity threefold, but they fail to upshift the apparent IC50 of a variety of OPs. Further development and optimization of these compounds may lead to pre- and/or postexposure therapeutics with broad-spectrum efficacy against pesticide and nerve agent poisoning. In addition, they could be used to complement the current therapeutic standard of care to increase the activity of uninhibited AChE, potentially increasing the efficacy of current therapeutics in addition to altering the therapeutic window.
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Affiliation(s)
- Richard R Chapleau
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright Patterson AFB, OH, USA Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - Craig A McElroy
- College of Pharmacy, Ohio State University, Columbus, OH, USA
| | - Christopher D Ruark
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright Patterson AFB, OH, USA Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - Emily J Fleming
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright Patterson AFB, OH, USA Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - Amy B Ghering
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright Patterson AFB, OH, USA Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - John J Schlager
- Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - Lee D Poeppelman
- Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
| | - Jeffery M Gearhart
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright Patterson AFB, OH, USA Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate, 711th Human Performance Wing, Air Force Research Laboratory (711 HPW/RHDJ), Wright Patterson AFB, OH, USA
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19
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Atsmon J, Brill-Almon E, Nadri-Shay C, Chertkoff R, Alon S, Shaikevich D, Volokhov I, Haim KY, Bartfeld D, Shulman A, Ruderfer I, Ben-Moshe T, Shilovitzky O, Soreq H, Shaaltiel Y. Preclinical and first-in-human evaluation of PRX-105, a PEGylated, plant-derived, recombinant human acetylcholinesterase-R. Toxicol Appl Pharmacol 2015; 287:202-9. [PMID: 26051873 DOI: 10.1016/j.taap.2015.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/27/2015] [Accepted: 06/01/2015] [Indexed: 12/18/2022]
Abstract
PRX-105 is a plant-derived recombinant version of the human 'read-through' acetylcholinesterase splice variant (AChE-R). Its active site structure is similar to that of the synaptic variant, and it displays the same affinity towards organophosphorus (OP) compounds. As such, PRX-105 may serve as a bio-scavenger for OP pesticides and chemical warfare agents. To assess its potential use in prophylaxis and treatment of OP poisoning we conducted several preliminary tests, reported in this paper. Intravenous (IV) PRX-105 was administered to mice either before or after exposure to an OP toxin. All mice who received an IV dose of 50nmol/kg PRX-105, 2min before being exposed to 1.33×LD50 and 1.5×LD50 of toxin and 10min after exposure to 1.5×LD50 survived. The pharmacokinetic and toxicity profiles of PRX-105 were evaluated in mice and mini-pigs. Following single and multiple IV doses (50 to 200mg/kg) no deaths occurred and no significant laboratory and histopathological changes were observed. The overall elimination half-life (t½) in mice was 994 (±173) min. Additionally, a first-in-human study, to assess the safety, tolerability and pharmacokinetics of the compound, was conducted in healthy volunteers. The t½ in humans was substantially longer than in mice (average 26.7h). Despite the small number of animals and human subjects who were assessed, the fact that PRX-105 exerts a protective and therapeutic effect following exposure to lethal doses of OP, its favorable safety profile and its relatively long half-life, renders it a promising candidate for treatment and prophylaxis against OP poisoning and warrants further investigation.
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Affiliation(s)
- Jacob Atsmon
- Clinical Research Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Israel
| | | | | | | | - Sari Alon
- Protalix Biotherapeutics, Science Park, Carmiel, Israel
| | - Dimitri Shaikevich
- Clinical Research Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Inna Volokhov
- Clinical Research Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Kirsten Y Haim
- Clinical Research Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Israel
| | | | - Avidor Shulman
- Protalix Biotherapeutics, Science Park, Carmiel, Israel.
| | - Ilya Ruderfer
- Protalix Biotherapeutics, Science Park, Carmiel, Israel
| | | | | | - Hermona Soreq
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
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Worek F, Horn G, Wille T, Thiermann H. Adaptation of a dynamic in vitro model with real-time determination of butyrylcholinesterase activity in the presence of cyclosarin and an oxime. Toxicol In Vitro 2015; 29:162-7. [DOI: 10.1016/j.tiv.2014.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 09/29/2014] [Accepted: 10/06/2014] [Indexed: 02/03/2023]
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21
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Brus B, Košak U, Turk S, Pišlar A, Coquelle N, Kos J, Stojan J, Colletier JP, Gobec S. Discovery, biological evaluation, and crystal structure of a novel nanomolar selective butyrylcholinesterase inhibitor. J Med Chem 2014; 57:8167-79. [PMID: 25226236 DOI: 10.1021/jm501195e] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Butyrylcholinesterase (BChE) is regarded as a promising drug target as its levels and activity significantly increase in the late stages of Alzheimer's disease. To discover novel BChE inhibitors, we used a hierarchical virtual screening protocol followed by biochemical evaluation of 40 highest scoring hit compounds. Three of the compounds identified showed significant inhibitory activities against BChE. The most potent, compound 1 (IC50 = 21.3 nM), was resynthesized and resolved into its pure enantiomers. A high degree of stereoselective activity was revealed, and a dissociation constant of 2.7 nM was determined for the most potent stereoisomer (+)-1. The crystal structure of human BChE in complex with compound (+)-1 was solved, revealing the binding mode and providing clues for potential optimization. Additionally, compound 1 inhibited amyloid β(1-42) peptide self-induced aggregation into fibrils (by 61.7% at 10 μM) and protected cultured SH-SY5Y cells against amyloid-β-induced toxicity. These data suggest that compound 1 represents a promising candidate for hit-to-lead follow-up in the drug-discovery process against Alzheimer's disease.
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Affiliation(s)
- Boris Brus
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
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22
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Brandhuber F, Zengerle M, Porwol L, Bierwisch A, Koller M, Reiter G, Worek F, Kubik S. Tabun scavengers based on hydroxamic acid containing cyclodextrins. Chem Commun (Camb) 2013; 49:3425-7. [PMID: 23503705 DOI: 10.1039/c3cc41290c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Arrangement of several hydroxamic acid-derived substituents along the cavity of a cyclodextrin ring leads to compounds that detoxify tabun in TRIS-HCl buffer at physiological pH and 37.0 °C with half-times as low as 3 min.
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Affiliation(s)
- Florian Brandhuber
- Institut für Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstraße 11, D-80937 München, Germany
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23
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Nachon F, Brazzolotto X, Trovaslet M, Masson P. Progress in the development of enzyme-based nerve agent bioscavengers. Chem Biol Interact 2013; 206:536-44. [PMID: 23811386 DOI: 10.1016/j.cbi.2013.06.012] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/15/2013] [Accepted: 06/18/2013] [Indexed: 11/17/2022]
Abstract
Acetylcholinesterase is the physiological target for acute toxicity of nerve agents. Attempts to protect acetylcholinesterase from phosphylation by nerve agents, is currently achieved by reversible inhibitors that transiently mask the enzyme active site. This approach either protects only peripheral acetylcholinesterase or may cause side effects. Thus, an alternative strategy consists in scavenging nerve agents in the bloodstream before they can reach acetylcholinesterase. Pre- or post-exposure administration of bioscavengers, enzymes that neutralize and detoxify organophosphorus molecules, is one of the major developments of new medical counter-measures. These enzymes act either as stoichiometric or catalytic bioscavengers. Human butyrylcholinesterase is the leading stoichiometric bioscavenger. Current efforts are devoted to its mass production with care to pharmacokinetic properties of the final product for extended lifetime. Development of specific reactivators of phosphylated butyrylcholinesterase, or variants with spontaneous reactivation activity is also envisioned for rapid in situ regeneration of the scavenger. Human paraoxonase 1 is the leading catalytic bioscavenger under development. Research efforts focus on improving its catalytic efficiency toward the most toxic isomers of nerve agents, by means of directed evolution-based strategies. Human prolidase appears to be another promising human enzyme. Other non-human efficient enzymes like bacterial phosphotriesterases or squid diisopropylfluorophosphatase are also considered though their intrinsic immunogenic properties remain challenging for use in humans. Encapsulation, PEGylation and other modifications are possible solutions to address this problem as well as that of their limited lifetime. Finally, gene therapy for in situ generation and delivery of bioscavengers is for the far future, but its proof of concept has been established.
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Affiliation(s)
- Florian Nachon
- Institut de Recherche Biomédicale des Armées, BP87, 38702 La Tronche Cédex, France.
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24
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Estour F, Letort S, Müller S, Kalakuntla R, Le Provost R, Wille T, Reiter G, Worek F, Lafont O, Gouhier G. Functionalized cyclodextrins bearing an alpha nucleophile – A promising way to degrade nerve agents. Chem Biol Interact 2013; 203:202-7. [DOI: 10.1016/j.cbi.2012.10.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/11/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
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25
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Rozengart EV, Basova NE, Moralev SN, Lushchekina SV, Masson P, Varfolomeev SD. Research on cholinesterases in the Soviet Union and Russia: A historical perspective. Chem Biol Interact 2013; 203:3-9. [DOI: 10.1016/j.cbi.2013.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Wandhammer M, de Koning M, van Grol M, Loiodice M, Saurel L, Noort D, Goeldner M, Nachon F. A step toward the reactivation of aged cholinesterases – Crystal structure of ligands binding to aged human butyrylcholinesterase. Chem Biol Interact 2013; 203:19-23. [DOI: 10.1016/j.cbi.2012.08.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/05/2012] [Accepted: 08/06/2012] [Indexed: 11/25/2022]
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27
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Hodgins SM, Kasten SA, Harrison J, Otto TC, Oliver ZP, Rezk P, Reeves TE, Chilukuri N, Cerasoli DM. Assessing protection against OP pesticides and nerve agents provided by wild-type HuPON1 purified from Trichoplusia ni larvae or induced via adenoviral infection. Chem Biol Interact 2013; 203:177-80. [DOI: 10.1016/j.cbi.2012.10.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/04/2012] [Accepted: 10/09/2012] [Indexed: 11/28/2022]
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28
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New modified β-cyclodextrin derivatives as detoxifying agents of chemical warfare agents (II). In vitro detoxification of cyclosarin (GF): General screening and toxicokinetic aspects of OP scavengers. Toxicol Lett 2013. [DOI: 10.1016/j.toxlet.2012.11.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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29
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Chemical polysialylation of human recombinant butyrylcholinesterase delivers a long-acting bioscavenger for nerve agents in vivo. Proc Natl Acad Sci U S A 2013; 110:1243-8. [PMID: 23297221 DOI: 10.1073/pnas.1211118110] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The creation of effective bioscavengers as a pretreatment for exposure to nerve agents is a challenging medical objective. We report a recombinant method using chemical polysialylation to generate bioscavengers stable in the bloodstream. Development of a CHO-based expression system using genes encoding human butyrylcholinesterase and a proline-rich peptide under elongation factor promoter control resulted in self-assembling, active enzyme multimers. Polysialylation gives bioscavengers with enhanced pharmacokinetics which protect mice against 4.2 LD(50) of S-(2-(diethylamino)ethyl) O-isobutyl methanephosphonothioate without perturbation of long-term behavior.
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30
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Brandhuber F, Zengerle M, Porwol L, Tenberken O, Thiermann H, Worek F, Kubik S, Reiter G. Detoxification of tabun at physiological pH mediated by substituted β-cyclodextrin and glucose derivatives containing oxime groups. Toxicology 2012; 302:163-71. [DOI: 10.1016/j.tox.2012.08.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 01/10/2023]
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31
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Wales ME, Reeves TE. Organophosphorus hydrolase as an in vivo catalytic nerve agent bioscavenger. Drug Test Anal 2012; 4:271-81. [DOI: 10.1002/dta.381] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 10/03/2011] [Accepted: 10/03/2011] [Indexed: 11/12/2022]
Affiliation(s)
- Melinda E. Wales
- Department of Biochemistry & Biophysics; Texas A&M University; College Station; TX; USA
| | - Tony E. Reeves
- Southwest Research Institute; Microencapsulation and Nanomaterials, Chemistry and Chemical Engineering Division; San Antonio; TX; USA
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32
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Collombet JM. Nerve agent intoxication: Recent neuropathophysiological findings and subsequent impact on medical management prospects. Toxicol Appl Pharmacol 2011; 255:229-41. [DOI: 10.1016/j.taap.2011.07.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 07/07/2011] [Accepted: 07/08/2011] [Indexed: 01/14/2023]
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His-tag truncated butyrylcholinesterase as a useful construct for in vitro characterization of wild-type and variant butyrylcholinesterases. Protein Expr Purif 2011; 80:22-7. [PMID: 21802514 DOI: 10.1016/j.pep.2011.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/10/2011] [Accepted: 07/13/2011] [Indexed: 10/18/2022]
Abstract
Human butyrylcholinesterase (BChE) can scavenge and thereby provide protection against various toxic esters, including organophosphate-based chemical warfare agents and the recreational drug cocaine. It is currently being used in molecular evolution studies to generate novel enzymes with improved ability to hydrolyze toxic ester compounds. Currently, the most commonly used purification strategies for recombinant BChE enzymes involve using affinity resins based on small molecule interactions with the enzyme's substrate binding site. However, as BChE variants are discovered and developed, a generic purification protocol that is insensitive to amino acid substitutions is necessary. In the current manuscript, an expression vector encoding a C-terminal truncation and a His₆-tag was designed for BChE and used to express recombinant "wild-type" enzyme and two variants (i.e., G117H BChE and G117H/E197Q BChE). All the three His₆-tagged enzymes were successfully purified via metal-affinity columns using similar procedures with good recovery. Steady-state kinetic parameters were determined for each enzyme, and values were compared to those obtained with the corresponding non-truncated non-His₆-tagged enzymes. Rates of inhibition by echothiophate, a model compound for organophosphate-based pesticides, and rates of oxime-mediated reactivation after inhibition with a nerve agent model compound were also determined for selected enzymes. Rates of spontaneous reactivation from ETP inhibition were determined for the G117H variants. In all instances examined, truncation of the C-terminus of BChE and introduction of a His₆-tag had no significant effects on the observed kinetic parameters, making this a highly useful construct for in vitro characterization of wild-type and variant BChEs.
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Trovaslet-Leroy M, Musilova L, Renault F, Brazzolotto X, Misik J, Novotny L, Froment MT, Gillon E, Loiodice M, Verdier L, Masson P, Rochu D, Jun D, Nachon F. Organophosphate hydrolases as catalytic bioscavengers of organophosphorus nerve agents. Toxicol Lett 2011; 206:14-23. [PMID: 21683774 DOI: 10.1016/j.toxlet.2011.05.1041] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 05/27/2011] [Accepted: 05/31/2011] [Indexed: 01/30/2023]
Abstract
Bioscavengers are molecules able to neutralize neurotoxic organophosphorus compounds (OP) before they can reach their biological target. Human butyrylcholinesterase (hBChE) is a natural bioscavenger each molecule of enzyme neutralizing one molecule of OP. The amount of natural enzyme is insufficient to achieve good protection. Thus, different strategies have been envisioned. The most straightforward consists in injecting a large dose of highly purified natural hBChE to increase the amount of bioscavenger in the bloodstream. This proved to be successful for protection against lethal doses of soman and VX but remains expensive. An improved strategy is to regenerate prophylactic cholinesterases (ChE) by administration of reactivators after exposure. But broad-spectrum efficient reactivators are still lacking, especially for inhibited hBChE. Cholinesterase mutants capable of reactivating spontaneously are another option. The G117H hBChE mutant has been a prototype. We present here the Y124H/Y72D mutant of human acetylcholinesterase; its spontaneous reactivation rate after V-agent inhibition is increased up to 110 fold. Catalytic bioscavengers, enzymes capable of hydrolyzing OP, present the best alternative. Mesophilic bacterial phosphotriesterase (PTE) is a candidate with good catalytic efficiency. Its enantioselectivity has been enhanced against the most potent OP isomers by rational design. We show that PEGylation of this enzyme improves its mean residence time in the rat blood stream 24-fold and its bioavailability 120-fold. Immunogenic issues remain to be solved. Human paraoxonase 1 (hPON1) is another promising candidate. However, its main drawback is that its phosphotriesterase activity is highly dependent on its environment. Recent progress has been made using a mammalian chimera of PON1, but we provide here additional data showing that this chimera is biochemically different from hPON1. Besides, the chimera is expected to suffer from immunogenic issues. Thus, we stress that interest for hPON1 must not fade away, and in particular, the 3D structure of the hPON1 eventually in complex with OP has to be solved.
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Affiliation(s)
- Marie Trovaslet-Leroy
- Département de Toxicologie, Institut de Recherches Biomédicales des Armées, 38700 La Tronche, France
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35
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Abstract
Kolinesteraze: struktura, uloga, inhibicijaAcetilkolinesteraza (AChE; E.C. 3.1.1.7) i butirilkolinesteraza (BChE; E.C. 3.1.1.8) enzimi su koji se zbog svoje uloge u organizmu intenzivno istražuju unutar područja biomedicine i toksikologije. Iako strukturno homologni, ovi enzimi razlikuju se prema katalitičkoj aktivnosti, odnosno specifičnosti prema supstratima koje mogu hidrolizirati te selektivnosti za vezanje mnogih liganada. U ovom radu dan je pregled dosadašnjih istraživanja kolinesteraza i njihovih interakcija s ligandima i inhibitorima te su izdvojene aminokiseline aktivnog mjesta koje sudjeluju u tim interakcijama.
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36
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Masson P. Evolution of and perspectives on therapeutic approaches to nerve agent poisoning. Toxicol Lett 2011; 206:5-13. [PMID: 21524695 DOI: 10.1016/j.toxlet.2011.04.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/08/2011] [Indexed: 01/18/2023]
Abstract
After more than 70 years of considerable efforts, research on medical defense against nerve agents has come to a standstill. Major progress in medical countermeasures was achieved between the 50s and 70s with the development of anticholinergic drugs and carbamate-based pretreatment, the introduction of pyridinium oximes as antidotes, and benzodiazepines in emergency treatments. These drugs ensure good protection of the peripheral nervous system and mitigate the acute effects of exposure to lethal doses of nerve agents. However, pyridostigmine and cholinesterase reactivators currently used in the armed forces do not protect/reactivate central acetylcholinesterases. Moreover, other drugs used are not sufficiently effective in protecting the central nervous system against seizures, irreversible brain damages and long-term sequelae of nerve agent poisoning.New developments of medical counter-measures focus on: (a) detoxification of organophosphorus molecules before they react with acetylcholinesterase and other physiological targets by administration of stoichiometric or catalytic scavengers; (b) protection and reactivation of central acetylcholinesterases, and (c) improvement of neuroprotection following delayed therapy.Future developments will aim at treatment of acute and long-term effects of low level exposure to nerve agents, research on alternative routes for optimizing drug delivery, and therapies. Though gene therapy for in situ generation of bioscavengers, and cell therapy based on neural progenitor engraftment for neuronal regeneration have been successfully explored, more studies are needed before practical medical applications can be made of these new approaches.
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Affiliation(s)
- Patrick Masson
- IRBA-CRSSA, Toxicology Dept., 38702 La Tronche Cedex, France.
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37
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X-ray crystallographic snapshots of reaction intermediates in the G117H mutant of human butyrylcholinesterase, a nerve agent target engineered into a catalytic bioscavenger. Biochem J 2011; 434:73-82. [PMID: 21091433 DOI: 10.1042/bj20101648] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OPs (organophosphylates) exert their acute toxicity through inhibition of acetylcholinesterase, by phosphylation of the catalytic serine residue. Engineering of human butyrylcholinesterase, by substitution of a histidine residue for the glycine residue at position 117, led to the creation of OP hydrolase activity. However, the lack of structural information and poor understanding of the hydrolytic mechanism of the G117H mutant has hampered further improvements in the catalytic activity. We have solved the crystallographic structure of the G117H mutant with a variety of ligands in its active site. A sulfate anion bound to the active site suggested the positioning for an OP prior to phosphylation. A fluoride anion was found in the active site when NaF was added to the crystallization buffer. In the fluoride complex, the imidazole ring from the His117 residue was substantially shifted, adopting a relaxed conformation probably close to that of the unliganded mutant enzyme. Additional X-ray structures were obtained from the transient covalent adducts formed upon reaction of the G117H mutant with the OPs echothiophate and VX [ethyl ({2-[bis(propan-2-yl)amino]ethyl}sulfanyl](methyl)phosphinate]. The position of the His117 residue shifted in response to the introduction of these adducts, overlaying the phosphylserine residue. These structural data suggest that the dephosphylation mechanism involves either a substantial conformational change of the His117 residue or an adjacent nucleophilic substitution by water.
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Amitay M, Shurki A. Hydrolysis of organophosphate compounds by mutant butyrylcholinesterase: A story of two histidines. Proteins 2010; 79:352-64. [DOI: 10.1002/prot.22864] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Müller S, Koller M, Le Provost R, Lafont O, Estour F, Wille T, Thiermann H, Worek F, Reiter G. In vitro detoxification of cyclosarin (GF) by modified cyclodextrins. Toxicol Lett 2010; 200:53-8. [PMID: 21035528 DOI: 10.1016/j.toxlet.2010.10.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
Abstract
Developing potent detoxification strategies for prophylaxis and therapy against organophosphate (OP) intoxication still represents a challenging task. Clinical application of numerous investigated substances including enzymes and low molecular scavengers like metal ions or nucleophiles could not yet be realised due to profound disadvantages. Presenting a promising attempt, cyclodextrins (CDs) efficiently enhance the degradation of some organophosphorus compounds. The present study examined the in vitro GF degradation mediated by three CDs and a nucleophilic precursor performed by mass spectrometric detection with ammonia chemical ionisation. All four compounds caused a notable enhancement of GF detoxification that was synergistically accelerated in the case of 2-O-(3-carboxy-4-iodosobenzyl)-β-cyclodextrin (IBA-β-CD) with the alpha-nucleophile 2-iodosobenzoic acid (IBA) grafted on the secondary face of β-cyclodextrin (β-CD). In vitro toxicokinetic investigations of CD derivatives are needed to evaluate the effect of slow terminal elimination phase of the more toxic (-)-GF shown for two CD-derivatives underlining the necessity of detecting the complete kinetic course of inactivation. The observed effect of fast high affinity binding (20-30%) represents an additional therapeutic option of an extremely rapid reduction of GF concentration in vivo. Distinctive differences in the course of reaction are detected depending on β-CD-derivatives, allowing a first inference of possible mechanisms and relevance of attached substituents. However, further profound investigation needs to be done to evaluate the basis of a clinical application of substituted CDs as potential detoxification agents.
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Affiliation(s)
- Susanne Müller
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
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Beck JM, Hadad CM. Reaction profiles of the interaction between sarin and acetylcholinesterase and the S203C mutant: model nucleophiles and QM/MM potential energy surfaces. Chem Biol Interact 2010; 187:220-4. [PMID: 20156428 PMCID: PMC2894988 DOI: 10.1016/j.cbi.2010.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/28/2010] [Accepted: 02/08/2010] [Indexed: 11/19/2022]
Abstract
The phosphonylation mechanism of AChE and the S203C mutation by sarin (GB) is evaluated using two reaction schemes: a small model nucleophile (ethoxide, CH(3)CH(2)O(-)) and quantum mechanical/molecular mechanical (QM/MM) simulations. Calculations utilizing small model nucleophiles indicate that the reaction barrier for addition to GB is the rate-limiting step for both ethoxide and ethyl thiolate (CH(3)CH(2)S(-)); moreover, the activation barrier for addition to the phosphorus center of GB by ethyl thiolate is significantly larger (13.2 kcal/mol) than for ethoxide (8.3 kcal/mol). The decomposition transition state for both nucleophiles was determined to be approximately 1 kcal/mol. QM/MM simulations for AChE suggest a similar reaction mechanism for phosphonylation of the catalytic S203; however, the relative energetics are altered significantly compared to the isolated system. QM/MM results indicate that formation of the penta-coordinate intermediate is the rate-limiting step in the enzymatic system, with an activation barrier of 3.6 kcal/mol. Hydrogen-bonding interactions between the fluoride leaving group of GB with Y124 in AChE are observed throughout the reaction profile. The S203C mutation alters the relative energetics of the reaction, increasing the energy barrier for formation of the penta-coordinate intermediate to a value of 4.5 kcal/mol; moreover, the penta-coordinate intermediate (as product) is stabilized by an additional 6 kcal/mol when compared to wild-type AChE.
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Affiliation(s)
- Jeremy M. Beck
- Department of Chemistry, The Ohio State University, 100 West 18Avenue, Columbus, OH 43210, USA
| | - Christopher M. Hadad
- Department of Chemistry, The Ohio State University, 100 West 18Avenue, Columbus, OH 43210, USA
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Vyas S, Beck JM, Xia S, Zhang J, Hadad CM. Butyrylcholinesterase and G116H, G116S, G117H, G117N, E197Q and G117H/E197Q mutants: a molecular dynamics study. Chem Biol Interact 2010; 187:241-5. [PMID: 20399202 PMCID: PMC2912153 DOI: 10.1016/j.cbi.2010.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 03/24/2010] [Accepted: 04/06/2010] [Indexed: 11/21/2022]
Abstract
Butyrylcholinesterase (BuChE) is a stoichiometric bioscavenger against organophosphorus (OP) nerve agent poisoning, and efforts to make BuChE variants that are catalytically active against a wide spectrum of nerve agents have been ongoing for the last decade. In order to understand the structural consequences for BuChE, we carried out extensive molecular dynamics (MD) simulations on wild-type BuChE (PDB ID: 1P0I) and several known and new variants of this enzyme, but without the presence of any ligand in the active site. The MD simulations on WT-BuChE identified two labile orientations for the catalytic serine, and also showed the likelihood of a backdoor. Upon changes at the G116 position, severe alterations around the active site region were identified. Simulations on both G117H and G117N variants showed the existence of a bound water molecule that is in close proximity to S198. Modeling of the E197Q mutant suggested that Q197 can be in two distinct orientations, one similar to the E202Q-AChE crystal structure and another in proximity to G439 and E441. The double mutant, G117H/E197Q, was found to have structural characteristics of both G117H and E197Q. In light of the computational results, previous experimental observations are discussed.
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Affiliation(s)
- Shubham Vyas
- Department of Chemistry, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210 USA
| | - Jeremy M. Beck
- Department of Chemistry, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210 USA
| | - Shijing Xia
- Department of Chemistry, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210 USA
| | - Jun Zhang
- Human BioMolecular Research Institute, 5310 Eastgate Mall, San Diego, CA 92121 USA
| | - Christopher M. Hadad
- Department of Chemistry, The Ohio State University, 100 West 18 Avenue, Columbus, Ohio 43210 USA
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42
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Structural approach to the aging of phosphylated cholinesterases. Chem Biol Interact 2010; 187:157-62. [DOI: 10.1016/j.cbi.2010.03.027] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Revised: 03/08/2010] [Accepted: 03/12/2010] [Indexed: 12/18/2022]
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Pseudo-catalytic scavenging: searching for a suitable reactivator of phosphorylated butyrylcholinesterase. Chem Biol Interact 2010; 187:167-71. [PMID: 20206154 DOI: 10.1016/j.cbi.2010.02.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/02/2010] [Accepted: 02/15/2010] [Indexed: 11/22/2022]
Abstract
Butyrylcholinesterase is considered to be an endogenous stoichiometric bioscavenger of organophosphorus compounds (OPs), but due to limited concentration of BChE in the organism, stoichiometric reduction of OP is not always sufficient. This can be improved by creating a pseudo-catalytic scavenger adding oximes as reactivators of inhibited exogenous BChE. In order to improve the BChE bioscavenging function in tabun or paraoxon poisoning, we tested in vitro reactivation of phosphorylated human plasma BChE by bispyridinium oximes varying in the length and type of the linker between rings, and in the position of the oxime group on the ring. Among the tested oximes, the most potent reactivators of tabun-inhibited BChE were K117 [1,1'-(2,2'-oxybis(ethane-2,1-diyl))bis(4-hydroxyiminomethyl pyridinium) bromide] and K127 [4-carbamoyl-1-(2-(2-(4-(hydroxyiminomethyl) pyridinium-1-yl)ethoxy)ethyl)pyridinium bromide]. Reactivation by these oximes (1mM) reached about 50% of control activity after only 20 min; however, reactivation stopped at 70%. Reactivation of paraoxon-inhibited BChE by all of the selected oximes was slow. Using molecular mechanics, we performed docking of the oximes to tabun-inhibited BChE in order to discuss possible structural modifications of bispyridinium oximes to improve reactivation of phosphorylated BChE.
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Barakat NH, Zheng X, Gilley CB, MacDonald M, Okolotowicz K, Cashman JR, Vyas S, Beck JM, Hadad CM, Zhang J. Chemical synthesis of two series of nerve agent model compounds and their stereoselective interaction with human acetylcholinesterase and human butyrylcholinesterase. Chem Res Toxicol 2010; 22:1669-79. [PMID: 19715346 DOI: 10.1021/tx900096j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Both G and V type nerve agents possess a center of chirality about phosphorus. The S(p) enantiomers are generally more potent inhibitors than their R(p) counterparts toward acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). To develop model compounds with defined centers of chirality that mimic the target nerve agent structures, we synthesized both the S(p) and the R(p) stereoisomers of two series of G type nerve agent model compounds in enantiomerically enriched form. The two series of model compounds contained identical substituents on the phosphorus as the G type agents, except that thiomethyl (CH(3)-S-) and thiocholine [(CH(3))(3)NCH(2)CH(2)-S-] groups were used to replace the traditional nerve agent leaving groups (i.e., fluoro for GB, GF, and GD and cyano for GA). Inhibition kinetic studies of the thiomethyl- and thiocholine-substituted series of nerve agent model compounds revealed that the S(p) enantiomers of both series of compounds showed greater inhibition potency toward AChE and BChE. The level of stereoselectivity, as indicated by the ratio of the bimolecular inhibition rate constants between S(p) and R(p) enantiomers, was greatest for the GF model compounds in both series. The thiocholine analogues were much more potent than the corresponding thiomethyl analogues. With the exception of the GA model compounds, both series showed greater potency against AChE than BChE. The stereoselectivity (i.e., S(p) > R(p)), enzyme selectivity, and dynamic range of inhibition potency contributed from these two series of compounds suggest that the combined application of these model compounds will provide useful research tools for understanding interactions of nerve agents with cholinesterase and other enzymes involved in nerve agent and organophosphate pharmacology. The potential of and limitations for using these model compounds in the development of biological therapeutics against nerve agent toxicity are also discussed.
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Affiliation(s)
- Nora H Barakat
- Human BioMolecular Research Institute, San Diego, California 92121, USA
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Zheng X, Okolotowicz K, Wang B, Macdonald M, Cashman JR, Zhang J. Direct detection of the hydrolysis of nerve agent model compounds using a fluorescent probe. Chem Biol Interact 2010; 187:330-4. [PMID: 20097185 DOI: 10.1016/j.cbi.2010.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 12/30/2009] [Accepted: 01/18/2010] [Indexed: 11/30/2022]
Abstract
Nerve agents are highly toxic organophosphorus compounds (OPs) that are used as chemical warfare agents. Developing a catalytic bioscavenger to efficiently detoxify nerve agents in the bloodstream of affected individuals has been recognized as an attractive approach to prevent nerve agent toxicity. However, the search for nerve agent catalysts has been hindered by the lack of efficient direct assays for nerve agent hydrolysis. In addition, authentic nerve agents are restricted and access to use for experiments by the general research community is prohibited. Herein we report development of a method that combines use of novel nerve agent model compounds possessing a thiocholine leaving group that reacts with the fluorescent thio-detection probe, BES-Thio, to afford detection of sub-micromolar amounts of nerve agent model compounds hydrolysis products. The detection sensitivity of BES-Thio assay was approximately 10 times better than the Ellman assay. This developed method is useful as a direct, sensitive screening method for evaluating OP hydrolysis efficiency from catalytic cholinesterases. When the assay was assembled in the presence of oxime, OP-inhibited cholinesterases that were able to be reactivated by specific oxime showed oxime-assisted enzyme-mediated OP hydrolysis. Therefore, this method is also useful to screen oxime analogs to identify novel agents that can reactivate OP-inhibited cholinesterases or to screen various enzymes to identify pseudo-catalytic bioscavengers that can be readily reactivated by clinically approved oximes.
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Affiliation(s)
- Xueying Zheng
- Human BioMolecular Research Institute, San Diego, CA 92121, United States
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Butyrylcholinesterase for protection from organophosphorus poisons: catalytic complexities and hysteretic behavior. Arch Biochem Biophys 2009; 494:107-20. [PMID: 20004171 DOI: 10.1016/j.abb.2009.12.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 11/24/2009] [Accepted: 12/01/2009] [Indexed: 12/13/2022]
Abstract
Butyrylcholinesterase is a promiscuous enzyme that displays complex kinetic behavior. It is toxicologically important because it detoxifies organophosphorus poisons (OP) by making a covalent bond with the OP. The OP and the butyrylcholinesterase are both inactivated in the process. Inactivation of butyrylcholinesterase has no adverse effects. However, inactivation of acetylcholinesterase in nerve synapses can be lethal. OP-inhibited butyrylcholinesterase and acetylcholinesterase can be reactivated with oximes provided the OP has not aged. Strategies for preventing the toxicity of OP include (a) treatment with an OP scavenger, (b) reaction of non-aged enzyme with oximes, (c) reactivation of aged enzyme, (d) slowing down aging with peripheral site ligands, and (e) design of mutants that rapidly hydrolyze OP. Option (a) has progressed through phase I clinical trials with human butyrylcholinesterase. Option (b) is in routine clinical use. The others are at the basic research level. Butyrylcholinesterase displays complex kinetic behavior including activation by positively charged esters, ability to hydrolyze amides, and a lag time (hysteresis) preceding hydrolysis of benzoylcholine and N-methylindoxyl acetate. Mass spectrometry has identified new OP binding motifs on tyrosine and lysine in proteins that have no active site serine. It is proposed, but not yet proven, that low dose exposure involves OP modification of proteins that have no active site serine.
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Otto TC, Harsch CK, Yeung DT, Magliery TJ, Cerasoli DM, Lenz DE. Dramatic differences in organophosphorus hydrolase activity between human and chimeric recombinant mammalian paraoxonase-1 enzymes. Biochemistry 2009; 48:10416-22. [PMID: 19764813 DOI: 10.1021/bi901161b] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human serum paraoxonase-1 (HuPON1) has the capacity to hydrolyze aryl esters, lactones, oxidized phospholipids, and organophosphorus (OP) compounds. HuPON1 and bacterially expressed chimeric recombinant PON1s (G2E6 and G3C9) differ by multiple amino acids, none of which are in the putative enzyme active site. To address the importance of these amino acid differences, the abilities of HuPON1, G2E6, G3C9, and several variants to hydrolyze phenyl acetate, paraoxon, and V-type OP nerve agents were examined. HuPON1 and G2E6 have a 10-fold greater catalytic efficiency toward phenyl acetate than G3C9. In contrast, bacterial PON1s are better able to promote hydrolysis of paraoxon, whereas HuPON1 is considerably better at catalyzing the hydrolysis of nerve agents VX and VR. These studies demonstrate that mutations distant from the active site of PON1 have large and unpredictable effects on the substrate specificities and possibly the hydrolytic mechanisms of HuPON1, G2E6, and G3C9. The replacement of residue H115 in the putative active site with tryptophan (H115W) has highly disparate effects on HuPON1 and G2E6. In HuPON1, variant H115W loses the ability to hydrolyze VR but has improved activity toward paraoxon and VX. The H115W variant of G2E6 has paraoxonase activity similar to that of wild-type G2E6, modest activity with phenyl acetate and VR, and enhanced VX hydrolysis. VR inhibits H115W HuPON1 competitively when paraoxon is the substrate and noncompetitively when VX is the substrate. We have identified the first variant of HuPON1, H115W, that displays significantly enhanced catalytic activity against an authentic V-type nerve agent.
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Affiliation(s)
- Tamara C Otto
- Physiology and Immunology Branch, Research Division, U.S. Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5400, USA
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Duysen EG, Li B, Lockridge O. The butyrylcholinesterase knockout mouse a research tool in the study of drug sensitivity, bio-distribution, obesity and Alzheimer's disease. Expert Opin Drug Metab Toxicol 2009; 5:523-8. [PMID: 19416087 DOI: 10.1517/17425250902915555] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Butyrylcholinesterase (BChE) mutations common in the human population may result in complete or partial BChE deficiency, making the BChE knockout (KO) mouse a model for human deficiencies. The BChE KO mouse cannot tolerate standard doses of the muscle relaxant succinylcholine or the Alzheimer's disease drugs huperzine A and donepezil. It is resistant to the asthma drug bambuterol. The importance of BChE in detoxication of cocaine has been demonstrated by hepatotoxicity and cardiotoxicity in cocaine-challenged BChE KO mice. The BChE KO mouse becomes obese on a high-fat diet, suggesting a role for BChE in fat metabolism. BChE serves as a backup for acetylcholinesterase by hydrolyzing the neurotransmitter acetylcholine in acetylcholinesterase knockout mice. Imaging studies show that BChE injected intrathecally crosses the blood-brain barrier. Mice, but not humans, have carboxylesterase in their blood. Carboxylesterase obscures the role of BChE in detoxication of organophosphorus pesticides. Future studies will make a double knockout that has neither BChE nor carboxylesterase. The double knockout is expected to be unusually sensitive to the toxicity of organophosphorus pesticides. Knowledge of drug sensitivities in the mouse model of human BChE deficiency will aid in understanding adverse drug effects in humans.
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Affiliation(s)
- Ellen G Duysen
- Researcher Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198 6805, USA.
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Aurbek N, Thiermann H, Eyer F, Eyer P, Worek F. Suitability of human butyrylcholinesterase as therapeutic marker and pseudo catalytic scavenger in organophosphate poisoning: A kinetic analysis. Toxicology 2009; 259:133-9. [DOI: 10.1016/j.tox.2009.02.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 02/20/2009] [Accepted: 02/20/2009] [Indexed: 10/21/2022]
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50
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Microcalorimetric study of the inhibition of butyrylcholinesterase by paraoxon. Anal Biochem 2009; 389:97-101. [PMID: 19341699 DOI: 10.1016/j.ab.2009.03.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2008] [Revised: 03/25/2009] [Accepted: 03/26/2009] [Indexed: 11/23/2022]
Abstract
The inhibition of horse serum butyrylcholinesterase (EC 3.1.1.8) by the organophosphorus compound paraoxon (diethyl 4-nitrophenyl phosphate) was studied by flow microcalorimetry at 37 degrees C in Tris buffer (pH 7.5) using a modification of the kinetic model described by Stojan and coworkers [J. Stojan, V. Marcel, S. Estrada-Mondaca, A. Klaebe, P. Masson, D. Fournier, A putative kinetic model for substrate metabolisation by Drosophila acetylcholinesterase, FEBS Lett. 440 (1998) 85-88]. The reversible steps of the inhibition were studied in the mixing cell of the calorimeter, whereas the irreversible step was studied in the flow-through cell. A new pseudo-first-order approximation was developed to allow the kinetic analysis of inhibition progress curves in the presence of substrate when a significant amount of substrate is transformed. This approximation also allowed one to compute an analytical expression of the calorimetric curves using a gamma distribution to describe the impulse response of the calorimeter. Fitting models to data by nonlinear regression, with simulated annealing as a stochastic optimization method, allowed the determination of all kinetic parameters. It was found that paraoxon binds to both the enzyme and acyl-enzyme, but with weak affinities (K(i) = 0.123 mM and K'(i) = 5.5 mM). A slight activation was observed at the lowest paraoxon concentrations and was attributed to the binding of the substrate to the enzyme-inhibitor complex. The bimolecular inhibition rate constant k(i) = 2.8 x 10(4) M(-1) s(-1) was in agreement with previous studies. It is hoped that the methods developed in this work will contribute to extending the application range of microcalorimetry in the field of irreversible inhibitors.
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