1
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Manna U, Das G, Hossain MA. Insights into the binding aspects of fluoride with neutral synthetic receptors. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214357] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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2
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De Boer D, Nguyen N, Mao J, Moore J, Sorin EJ. A Comprehensive Review of Cholinesterase Modeling and Simulation. Biomolecules 2021; 11:580. [PMID: 33920972 PMCID: PMC8071298 DOI: 10.3390/biom11040580] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/08/2021] [Accepted: 04/11/2021] [Indexed: 01/18/2023] Open
Abstract
The present article reviews published efforts to study acetylcholinesterase and butyrylcholinesterase structure and function using computer-based modeling and simulation techniques. Structures and models of both enzymes from various organisms, including rays, mice, and humans, are discussed to highlight key structural similarities in the active site gorges of the two enzymes, such as flexibility, binding site location, and function, as well as differences, such as gorge volume and binding site residue composition. Catalytic studies are also described, with an emphasis on the mechanism of acetylcholine hydrolysis by each enzyme and novel mutants that increase catalytic efficiency. The inhibitory activities of myriad compounds have been computationally assessed, primarily through Monte Carlo-based docking calculations and molecular dynamics simulations. Pharmaceutical compounds examined herein include FDA-approved therapeutics and their derivatives, as well as several other prescription drug derivatives. Cholinesterase interactions with both narcotics and organophosphate compounds are discussed, with the latter focusing primarily on molecular recognition studies of potential therapeutic value and on improving our understanding of the reactivation of cholinesterases that are bound to toxins. This review also explores the inhibitory properties of several other organic and biological moieties, as well as advancements in virtual screening methodologies with respect to these enzymes.
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Affiliation(s)
- Danna De Boer
- Department of Chemistry & Biochemistry, California State University, Long Beach, CA 90840, USA;
| | - Nguyet Nguyen
- Department of Chemical Engineering, California State University, Long Beach, CA 90840, USA; (N.N.); (J.M.)
| | - Jia Mao
- Department of Chemical Engineering, California State University, Long Beach, CA 90840, USA; (N.N.); (J.M.)
| | - Jessica Moore
- Department of Biomedical Engineering, California State University, Long Beach, CA 90840, USA;
| | - Eric J. Sorin
- Department of Chemistry & Biochemistry, California State University, Long Beach, CA 90840, USA;
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3
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Computational studies on cholinesterases: Strengthening our understanding of the integration of structure, dynamics and function. Neuropharmacology 2020; 179:108265. [DOI: 10.1016/j.neuropharm.2020.108265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/21/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022]
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4
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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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5
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Vaknine S, Soreq H. Central and peripheral anti-inflammatory effects of acetylcholinesterase inhibitors. Neuropharmacology 2020; 168:108020. [PMID: 32143069 DOI: 10.1016/j.neuropharm.2020.108020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/09/2020] [Accepted: 02/25/2020] [Indexed: 12/31/2022]
Abstract
Acetylcholinesterase (AChE) inhibitors modulate acetylcholine hydrolysis and hence play a key role in determining the cholinergic tone and in implementing its impact on the cholinergic blockade of inflammatory processes. Such inhibitors may include rapidly acting small molecule AChE-blocking drugs and poisonous anti-AChE insecticides or war agent inhibitors which penetrate both body and brain. Notably, traumatized patients may be hyper-sensitized to anti-AChEs due to their impaired cholinergic tone, higher levels of circulation pro-inflammatory cytokines and exacerbated peripheral inflammatory responses. Those largely depend on the innate-immune system yet reach the brain via vagus pathways and/or disrupted blood-brain-barrier. Other regulators of the neuro-inflammatory cascade are AChE-targeted microRNAs (miRs) and synthetic chemically protected oligonucleotide blockers thereof, whose size prevents direct brain penetrance. Nevertheless, these larger molecules may exert parallel albeit slower inflammatory regulating effects on brain and body tissues. Additionally, oligonucleotide aptamers interacting with innate immune Toll-Like Receptors (TLRs) may control inflammation through diverse routes and in different rates. Such aptamers may compete with the action of both small molecule inhibitors and AChE-inhibiting miRs in peripheral tissues including muscle and intestine. However, rapid adaptation processes, visualized in neuromuscular junctions enable murine survival under otherwise lethal anti-cholinesterase exposure; and both miR inhibitors and TLR-modulating aptamers may exert body-brain signals protecting experimental mice from acute inflammation. The complex variety of AChE inhibiting molecules identifies diverse body-brain communication pathways which may rapidly induce long-lasting central reactions to peripheral stressful and inflammatory insults in both mice and men. This article is part of the special issue entitled 'Acetylcholinesterase Inhibitors: From Bench to Bedside to Battlefield'.
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Affiliation(s)
- Shani Vaknine
- The Edmond and Lily Safra Center of Brain Science, The Life Sciences Institute, The Hebrew University of Jerusalem, 9190401, Israel
| | - Hermona Soreq
- The Edmond and Lily Safra Center of Brain Science, The Life Sciences Institute, The Hebrew University of Jerusalem, 9190401, Israel.
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6
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McGarry KG, Lalisse RF, Moyer RA, Johnson KM, Tallan AM, Winters TP, Taris JE, McElroy CA, Lemmon EE, Shafaat HS, Fan Y, Deal A, Marguet SC, Harvilchuck JA, Hadad CM, Wood DW. A Novel, Modified Human Butyrylcholinesterase Catalytically Degrades the Chemical Warfare Nerve Agent, Sarin. Toxicol Sci 2019; 174:133-146. [DOI: 10.1093/toxsci/kfz251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Abstract
Chemical warfare nerve agents (CWNAs) present a global threat to both military and civilian populations. The acute toxicity of CWNAs stems from their ability to effectively inhibit acetylcholinesterase (AChE). This inhibition can lead to uncontrolled cholinergic cellular signaling, resulting in cholinergic crisis and, ultimately, death. Although the current FDA-approved standard of care is moderately effective when administered early, development of novel treatment strategies is necessary. Butyrylcholinesterase (BChE) is an enzyme which displays a high degree of structural homology to AChE. Unlike AChE, the roles of BChE are uncertain and possibilities are still being explored. However, BChE appears to primarily serve as a bioscavenger of toxic esters due to its ability to accommodate a wide variety of substrates within its active site. Like AChE, BChE is also readily inhibited by CWNAs. Due to its high affinity for binding CWNAs, and that null-BChE yields no apparent health effects, exogenous BChE has been explored as a candidate therapeutic for CWNA intoxication. Despite years of research, minimal strides have been made to develop a catalytic bioscavenger. Furthermore, BChE is only in early clinical trials as a stoichiometric bioscavenger of CWNAs, and large quantities must be administered to treat CWNA toxicity. Here, we describe previously unidentified mutations to residues within and adjacent to the acyl binding pocket (positions 282–285 were mutagenized from YGTP to NHML) of BChE that confer catalytic degradation of the CWNA, sarin. These mutations, along with corresponding future efforts, may finally lead to a novel therapeutic to combat CWNA intoxication.
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Affiliation(s)
- Kevin G McGarry
- Battelle Memorial Institute, Columbus, Ohio
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
| | - Remy F Lalisse
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | | | | | - Alexi M Tallan
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
| | | | - Joeseph E Taris
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
| | - Craig A McElroy
- College of Pharmacy, The Ohio State University, Columbus, Ohio
| | | | - Hannah S Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Yamin Fan
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
| | - Aniliese Deal
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
| | - Sean C Marguet
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | | | - Christopher M Hadad
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - David W Wood
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio
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7
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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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8
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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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9
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Comparison of the Binding of Reversible Inhibitors to Human Butyrylcholinesterase and Acetylcholinesterase: A Crystallographic, Kinetic and Calorimetric Study. Molecules 2017; 22:molecules22122098. [PMID: 29186056 PMCID: PMC6149722 DOI: 10.3390/molecules22122098] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/26/2017] [Accepted: 11/27/2017] [Indexed: 12/17/2022] Open
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) hydrolyze the neurotransmitter acetylcholine and, thereby, function as coregulators of cholinergic neurotransmission. Although closely related, these enzymes display very different substrate specificities that only partially overlap. This disparity is largely due to differences in the number of aromatic residues lining the active site gorge, which leads to large differences in the shape of the gorge and potentially to distinct interactions with an individual ligand. Considerable structural information is available for the binding of a wide diversity of ligands to AChE. In contrast, structural data on the binding of reversible ligands to BChE are lacking. In a recent effort, an inhibitor competition approach was used to probe the overlap of ligand binding sites in BChE. Here, we extend this study by solving the crystal structures of human BChE in complex with five reversible ligands, namely, decamethonium, thioflavin T, propidium, huprine, and ethopropazine. We compare these structures to equivalent AChE complexes when available in the protein data bank and supplement this comparison with kinetic data and observations from isothermal titration calorimetry. This new information now allows us to define the binding mode of various ligand families and will be of importance in designing specific reversible ligands of BChE that behave as inhibitors or reactivators.
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10
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Stojan J. Rapid Mechanistic Evaluation and Parameter Estimation of Putative Inhibitors in a Single-Step Progress-Curve Analysis: The Case of Horse Butyrylcholinesterase. Molecules 2017; 22:molecules22081248. [PMID: 28933751 PMCID: PMC6152194 DOI: 10.3390/molecules22081248] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/21/2017] [Indexed: 11/22/2022] Open
Abstract
Highly efficient and rapid lead compound evaluation for estimation of inhibition parameters and type of inhibition is proposed. This is based on a single progress-curve measurement in the presence of each candidate compound, followed by the simultaneous analysis of all of these curves using the ENZO enzyme kinetics suite, which can be implemented as a web application. In the first step, all of the candidate ligands are tested as competitive inhibitors. Where the theoretical curves do not correspond to the experimental data, minimal additional measurements are added, with subsequent processing according to modified reaction mechanisms.
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Affiliation(s)
- Jure Stojan
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazovtrg 2, 1000 Ljubljana, Slovenia.
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11
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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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12
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Characterization of butyrylcholinesterase in bovine serum. Chem Biol Interact 2017; 266:17-27. [PMID: 28189703 DOI: 10.1016/j.cbi.2017.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/25/2017] [Accepted: 02/07/2017] [Indexed: 02/07/2023]
Abstract
Human butyrylcholinesterase (HuBChE) protects from nerve agent toxicity. Our goal was to determine whether bovine serum could be used as a source of BChE. Bovine BChE (BoBChE) was immunopurified from 100 mL fetal bovine serum (FBS) or 380 mL adult bovine serum by binding to immobilized monoclonal mAb2. Bound proteins were digested with trypsin and analyzed by liquid chromatography-tandem mass spectrometry. The results proved that FBS and adult bovine serum contain BoBChE. The concentration of BoBChE was estimated to be 0.04 μg/mL in FBS, and 0.03 μg/mL in adult bovine serum, values lower than the 4 μg/mL BChE in human serum. Nondenaturing gel electrophoresis showed that monoclonal mAb2 bound BoBChE but not bovine acetylcholinesterase (BoAChE) and confirmed that FBS contains BoBChE and BoAChE. Recombinant bovine BChE (rBoBChE) expressed in serum-free culture medium spontaneously reactivated from inhibition by chlorpyrifos oxon at a rate of 0.0023 min-1 (t1/2 = 301 min-1) and aged at a rate of 0.0138 min-1 (t1/2 = 50 min-1). Both BoBChE and HuBChE have 574 amino acids per subunit and 90% sequence identity. However, the apparent size of serum BoBChE and rBoBChE tetramers was much greater than the 340,000 Da of HuBChE tetramers. Whereas HuBChE tetramers include short polyproline rich peptides derived from lamellipodin, no polyproline peptides have been identified in BoBChE. We hypothesize that BoBChE tetramers use a large polyproline-rich protein to organize subunits into a tetramer and that the low concentration of BoBChE in serum is explained by limited quantities of an unidentified polyproline-rich protein.
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13
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New insights on molecular interactions of organophosphorus pesticides with esterases. Toxicology 2017; 376:30-43. [DOI: 10.1016/j.tox.2016.06.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 05/25/2016] [Accepted: 06/10/2016] [Indexed: 01/01/2023]
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14
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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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15
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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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16
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Understanding the non-catalytic behavior of human butyrylcholinesterase silent variants: Comparison of wild-type enzyme, catalytically active Ala328Cys mutant, and silent Ala328Asp variant. Chem Biol Interact 2016; 259:223-232. [PMID: 27062896 DOI: 10.1016/j.cbi.2016.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 03/15/2016] [Accepted: 04/04/2016] [Indexed: 11/24/2022]
Abstract
Conformational dynamics of wild-type human butyrylcholinesterase (BChE), two mutants of residue Ala328, the catalytically active Ala328Cys, and the catalytically inactive (silent) Ala328Asp, and their interactions with butyrylcholine were studied. The aim was to understand the molecular mechanisms by which point mutations may lead to silent BChE variant or alter catalytic activity. Importance of BChE natural variants is due to medical consequences, i.e. prolonged apnea, following administration of the myorelaxant esters, succinylcholine and mivacurium. Comparison of molecular dynamics (MD) simulations for the three model systems showed that: 1) the active mutant Ala328Cys mutant has some changes in configuration of catalytic residues, which do not prevent binding of butyrylcholine to the active site; 2) in the naturally-occurring silent variant Ala328Asp, the Asp328 carboxylate may either form a salt bridge with Lys339 or a H-bond with His438. In the first case, the Ω-loop swings off the gorge, disrupting the π-cation binding site and the catalytic triad. In the second case, binding of cationic substrates in the catalytic center is also impaired. MD simulations carried out in 0.15 M NaCl, close to physiological ionic strength conditions, favored the second situation. It was seen that Asp328 forms a H-bond with the catalytic triad His438, which in turn disrupts the catalytic machinery. Therefore, we concluded that the Ala328Asp variant is not catalytically active because of that dramatic event. Computational results, consistent with in vitro biochemical data and clinical observations, validate our MD approach.
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17
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Mabbitt PD, Correy GJ, Meirelles T, Fraser NJ, Coote ML, Jackson CJ. Conformational Disorganization within the Active Site of a Recently Evolved Organophosphate Hydrolase Limits Its Catalytic Efficiency. Biochemistry 2016; 55:1408-17. [DOI: 10.1021/acs.biochem.5b01322] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Peter D. Mabbitt
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
| | - Galen J. Correy
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
| | - Tamara Meirelles
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
| | - Nicholas J. Fraser
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
| | - Michelle L. Coote
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
- ARC Centre of
Excellence for Electromaterials Science
| | - Colin J. Jackson
- Research
School of Chemistry, Australian National University, Acton 2601, Canberra, Australia
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18
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Nemukhin AV, Kulakova AM, Lushchekina SV, Ermilov AY, Varfolomeev SD. Modeling chemical transformations at the active sites of cholinesterases by quantum-based simulations. ACTA ACUST UNITED AC 2016. [DOI: 10.3103/s0027131415060061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Jang YJ, Kim K, Tsay OG, Atwood DA, Churchill DG. Update 1 of: Destruction and Detection of Chemical Warfare Agents. Chem Rev 2015; 115:PR1-76. [DOI: 10.1021/acs.chemrev.5b00402] [Citation(s) in RCA: 249] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yoon Jeong Jang
- Molecular Logic Gate Laboratory, Department of Chemistry, KAIST, Daejeon, 305-701, Republic of Korea
| | - Kibong Kim
- Molecular Logic Gate Laboratory, Department of Chemistry, KAIST, Daejeon, 305-701, Republic of Korea
| | - Olga G. Tsay
- Molecular Logic Gate Laboratory, Department of Chemistry, KAIST, Daejeon, 305-701, Republic of Korea
| | - David A. Atwood
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - David G. Churchill
- Molecular Logic Gate Laboratory, Department of Chemistry, KAIST, Daejeon, 305-701, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305−701, Republic of Korea
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20
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Kulakova A, Lushchekina S, Grigorenko B, Nemukhin A. Modeling reactivation of the phosphorylated human butyrylcholinesterase by QM(DFTB)/MM calculations. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2015. [DOI: 10.1142/s0219633615500510] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human butyrylcholinesterase (BChE) is a bioscavenger that protects the enzyme which is critical for the central nerve system, acetylcholinesterase, from poisoning by organophosphorus agents. Elucidating the details of the hydrolysis reaction mechanism is important to understand how the phosphorylated BChE can be reactivated. Application of the QM(DFTB)/MM(AMBER) method to construct the minimum energy pathways for the hydrolysis reaction of the diethylphosphorylated BChE allowed us to suggest a mechanism of reactivation of the wild-type and the G117H mutated enzyme. Unlike previous approaches assuming that either His438 or His117 serves as a general base in the catalysis, in our proposal the Glu197 residue is responsible for activation of the nucleophilic water molecule (Wat) leading to the chemical transformations that restore the catalytic Ser198 residue in BChE. In agreement with the experimental data, it is shown that the G117H mutation facilitates the reactivation of the inhibited enzyme.
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Affiliation(s)
- Anna Kulakova
- Chemistry Department, M. V. Lomonosov Moscow State University, 1-3 Leninskiye Gory, Moscow 119991, Russia
| | - Sofya Lushchekina
- N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygin Street, Moscow 119334, Russia
| | - Bella Grigorenko
- Chemistry Department, M. V. Lomonosov Moscow State University, 1-3 Leninskiye Gory, Moscow 119991, Russia
- N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygin Street, Moscow 119334, Russia
| | - Alexander Nemukhin
- Chemistry Department, M. V. Lomonosov Moscow State University, 1-3 Leninskiye Gory, Moscow 119991, Russia
- N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygin Street, Moscow 119334, Russia
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Rauwerdink A, Kazlauskas RJ. How the Same Core Catalytic Machinery Catalyzes 17 Different Reactions: the Serine-Histidine-Aspartate Catalytic Triad of α/β-Hydrolase Fold Enzymes. ACS Catal 2015; 5:6153-6176. [PMID: 28580193 DOI: 10.1021/acscatal.5b01539] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enzymes within a family often catalyze different reactions. In some cases, this variety stems from different catalytic machinery, but in other cases the machinery is identical; nevertheless, the enzymes catalyze different reactions. In this review, we examine the subset of α/β-hydrolase fold enzymes that contain the serine-histidine-aspartate catalytic triad. In spite of having the same protein fold and the same core catalytic machinery, these enzymes catalyze seventeen different reaction mechanisms. The most common reactions are hydrolysis of C-O, C-N and C-C bonds (Enzyme Classification (EC) group 3), but other enzymes are oxidoreductases (EC group 1), acyl transferases (EC group 2), lyases (EC group 4) or isomerases (EC group 5). Hydrolysis reactions often follow the canonical esterase mechanism, but eight variations occur where either the formation or cleavage of the acyl enzyme intermediate differs. The remaining eight mechanisms are lyase-type elimination reactions, which do not have an acyl enzyme intermediate and, in four cases, do not even require the catalytic serine. This diversity of mechanisms from the same catalytic triad stems from the ability of the enzymes to bind different substrates, from the requirements for different chemical steps imposed by these new substrates and, only in about half of the cases, from additional hydrogen bond partners or additional general acids/bases in the active site. This detailed analysis shows that binding differences and non-catalytic residues create new mechanisms and are essential for understanding and designing efficient enzymes.
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Affiliation(s)
- Alissa Rauwerdink
- Department of Biochemistry, Molecular Biology & Biophysics and The Biotechnology Institute, University of Minnesota, Saint Paul, Minnesota 55108, United States
| | - Romas J. Kazlauskas
- Department of Biochemistry, Molecular Biology & Biophysics and The Biotechnology Institute, University of Minnesota, Saint Paul, Minnesota 55108, United States
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22
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Legler PM, Boisvert SM, Compton JR, Millard CB. Development of organophosphate hydrolase activity in a bacterial homolog of human cholinesterase. Front Chem 2014; 2:46. [PMID: 25077141 PMCID: PMC4100338 DOI: 10.3389/fchem.2014.00046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 06/19/2014] [Indexed: 01/10/2023] Open
Abstract
We applied a combination of rational design and directed evolution (DE) to Bacillus subtilis p-nitrobenzyl esterase (pNBE) with the goal of enhancing organophosphorus acid anhydride hydrolase (OPAAH) activity. DE started with a designed variant, pNBE A107H, carrying a histidine homologous with human butyrylcholinesterase G117H to find complementary mutations that further enhance its OPAAH activity. Five sites were selected (G105, G106, A107, A190, and A400) within a 6.7 Å radius of the nucleophilic serine Oγ. All 95 variants were screened for esterase activity with a set of five substrates: pNP-acetate, pNP-butyrate, acetylthiocholine, butyrylthiocholine, or benzoylthiocholine. A microscale assay for OPAAH activity was developed for screening DE libraries. Reductions in esterase activity were generally concomitant with enhancements in OPAAH activity. One variant, A107K, showed an unexpected 7-fold increase in its k cat/K m for benzoylthiocholine, demonstrating that it is also possible to enhance the cholinesterase activity of pNBE. Moreover, DE resulted in at least three variants with modestly enhanced OPAAH activity compared to wild type pNBE. A107H/A190C showed a 50-fold increase in paraoxonase activity and underwent a slow time- and temperature-dependent change affecting the hydrolysis of OPAA and ester substrates. Structural analysis suggests that pNBE may represent a precursor leading to human cholinesterase and carboxylesterase 1 through extension of two vestigial specificity loops; a preliminary attempt to transfer the Ω-loop of BChE into pNBE is described. Unlike butyrylcholinesterase and pNBE, introducing a G143H mutation (equivalent to G117H) did not confer detectable OP hydrolase activity on human carboxylesterase 1 (hCE1). We discuss the use of pNBE as a surrogate scaffold for the mammalian esterases, and the importance of the oxyanion-hole residues for enhancing the OPAAH activity of selected serine hydrolases.
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Affiliation(s)
- Patricia M. Legler
- Naval Research Laboratory, Center for Bio/Molecular Science and EngineeringWashington, DC, USA
| | | | | | - Charles B. Millard
- United States Army Medical Research and Materiel CommandFort Detrick, MD, USA
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23
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Brugnara A, Topić F, Rissanen K, Lande ADL, Colasson B, Reinaud O. Selective recognition of fluoride anion in water by a copper(ii) center embedded in a hydrophobic cavity. Chem Sci 2014. [DOI: 10.1039/c4sc01457j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
CuII coordination combined with hydrophobic pocket hosting allows for strong and selective fluoride binding in water at near neutral pH.
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Affiliation(s)
- Andrea Brugnara
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques
- CNRS UMR 8601
- Université Paris Descartes
- 75006 Paris, France
| | - Filip Topić
- Department of Chemistry
- Nanoscience Center
- University of Jyväskylä
- 40014 Jyväskylä, Finland
| | - Kari Rissanen
- Department of Chemistry
- Nanoscience Center
- University of Jyväskylä
- 40014 Jyväskylä, Finland
| | - Aurélien de la Lande
- Laboratoire de Chimie Physique
- CNRS UMR 8000
- Université Paris-Sud 11
- 91400 Orsay, France
| | - Benoit Colasson
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques
- CNRS UMR 8601
- Université Paris Descartes
- 75006 Paris, France
| | - Olivia Reinaud
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques
- CNRS UMR 8601
- Université Paris Descartes
- 75006 Paris, France
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24
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Bennion BJ, Lau EY, Fattebert JL, Huang P, Schwegler E, Corning W, Lightstone FC. MODELING THE BINDING OF CWAs TO AChE AND BuChE. ACTA ACUST UNITED AC 2013. [DOI: 10.31482/mmsl.2013.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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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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26
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Cametti M, Rissanen K. Highlights on contemporary recognition and sensing of fluoride anion in solution and in the solid state. Chem Soc Rev 2012. [PMID: 23188119 DOI: 10.1039/c2cs35439j] [Citation(s) in RCA: 241] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The fluoride anion has recently gained well deserved attention among the scientific community for its importance in many fields of human activities, but also for concerns on its effect on health and the environment. Although surprisingly overlooked in systematic studies in the past, fluoride has nowadays become a topical target in the field of anion recognition. A multitude of scientific reports are published every year where the establishment of efficient and specific interaction with fluoride is sought in polar and aqueous media. Here, the emphasis is directed to a detailed description of the most interesting contemporary studies in the field, with a particular focus given to those published in the last few years.
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Affiliation(s)
- Massimo Cametti
- Department of Chemistry, Materials and Chemical Engineering Giulio Natta, Politecnico di Milano, Via Mancinelli 7, I-20131, Milan, Italy.
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27
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Yao Y, Liu J, Zhan CG. Why does the G117H mutation considerably improve the activity of human butyrylcholinesterase against sarin? Insights from quantum mechanical/molecular mechanical free energy calculations. Biochemistry 2012; 51:8980-92. [PMID: 23092211 DOI: 10.1021/bi3009246] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human butyrylcholinesterase (BChE) is recognized as the most promising bioscavenger for organophosphorus (OP) warfare nerve agents. The G117H mutant of human BChE has been identified as a potential catalytic bioscavenger with a remarkably improved activity against OP nerve agents such as sarin, but it still does not satisfy the clinical use. For further design of the higher-activity mutants against OP nerve agents, it is essential to understand how the G117H mutation improves the activity. The reaction mechanisms and the free energy profiles for spontaneous reactivation of wild-type BChE and its G117H mutant phosphorylated by sarin have been explored, in this study, by performing first-principles quantum mechanical/molecular mechanical free energy calculations, and the remarkable role of the G117H mutation on the activity has been elucidated. For both the wild-type and G117H mutant enzymes, H438 acts as a general base to initiate the spontaneous reactivation that consists of two reaction steps: the nucleophilic attack at the phosphorus by a water molecule and decomposition of the pentacoordinated phosphorus intermediate. The calculated overall free energy barriers, i.e., 30.2 and 23.9 kcal/mol for the wild type and G117H mutant, respectively, are in good agreement with available experimental kinetic data. On the basis of the calculated results, the mutated residue (H117 in the G117H mutant) cannot initiate the spontaneous reactivation as a general base. Instead, it skews the oxyanion hole and makes the phosphorus more open to the nucleophilic water molecule, resulting in a remarkable change in the rate-determining step and significantly improved catalytic activity of human BChE.
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Affiliation(s)
- Yuan Yao
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
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28
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Brazzolotto X, Wandhammer M, Ronco C, Trovaslet M, Jean L, Lockridge O, Renard PY, Nachon F. Human butyrylcholinesterase produced in insect cells: huprine-based affinity purification and crystal structure. FEBS J 2012; 279:2905-16. [DOI: 10.1111/j.1742-4658.2012.08672.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lebedev AA, Young P, Isupov MN, Moroz OV, Vagin AA, Murshudov GN. JLigand: a graphical tool for the CCP4 template-restraint library. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:431-40. [PMID: 22505263 PMCID: PMC3322602 DOI: 10.1107/s090744491200251x] [Citation(s) in RCA: 333] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 01/19/2012] [Indexed: 12/30/2022]
Abstract
Biological macromolecules are polymers and therefore the restraints for macromolecular refinement can be subdivided into two sets: restraints that are applied to atoms that all belong to the same monomer and restraints that are associated with the covalent bonds between monomers. The CCP4 template-restraint library contains three types of data entries defining template restraints: descriptions of monomers and their modifications, both used for intramonomer restraints, and descriptions of links for intermonomer restraints. The library provides generic descriptions of modifications and links for protein, DNA and RNA chains, and for some post-translational modifications including glycosylation. Structure-specific template restraints can be defined in a user's additional restraint library. Here, JLigand, a new CCP4 graphical interface to LibCheck and REFMAC that has been developed to manage the user's library and generate new monomer entries is described, as well as new entries for links and associated modifications.
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Affiliation(s)
- Andrey A Lebedev
- CCP4, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, England.
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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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Wandhammer M, Carletti E, Van der Schans M, Gillon E, Nicolet Y, Masson P, Goeldner M, Noort D, Nachon F. Structural study of the complex stereoselectivity of human butyrylcholinesterase for the neurotoxic V-agents. J Biol Chem 2011; 286:16783-9. [PMID: 21454498 PMCID: PMC3089521 DOI: 10.1074/jbc.m110.209569] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 02/28/2011] [Indexed: 11/06/2022] Open
Abstract
Nerve agents are chiral organophosphate compounds (OPs) that exert their acute toxicity by phosphorylating the catalytic serine of acetylcholinesterase (AChE). The inhibited cholinesterases can be reactivated using oximes, but a spontaneous time-dependent process called aging alters the adduct, leading to resistance toward oxime reactivation. Human butyrylcholinesterase (BChE) functions as a bioscavenger, protecting the cholinergic system against OPs. The stereoselectivity of BChE is an important parameter for its efficiency at scavenging the most toxic OPs enantiomer for AChE. Crystals of BChE inhibited in solution or in cristallo with racemic V-agents (VX, Russian VX, and Chinese VX) systematically show the formation of the P(S) adduct. In this configuration, no catalysis of aging seems possible as confirmed by the three-dimensional structures of the three conjugates incubated over a period exceeding a week. Crystals of BChE soaked in optically pure VX(R)-(+) and VX(S)-(-) solutions lead to the formation of the P(S) and P(R) adduct, respectively. These structural data support an in-line phosphonylation mechanism. Additionally, they show that BChE reacts with VX(R)-(+) in the presence of racemic mixture of V-agents, at odds with earlier kinetic results showing a moderate higher inhibition rate for VX(S)-(-). These combined results suggest that the simultaneous presence of both enantiomers alters the enzyme stereoselectivity. In summary, the three-dimensional data show that BChE reacts preferentially with P(R) enantiomer of V-agents and does not age, in complete contrast to AChE, which is selectively inhibited by the P(S) enantiomer and ages.
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Affiliation(s)
- Marielle Wandhammer
- From the Département de Toxicologie, Institut de Recherche Biomédicale des Armées-CRSSA, 38700 La Tronche, France
- the Laboratoire de Conception et Application de Molécules Bioactives, UMR 7199, Faculté de Pharmacie, 67400 Illkirch, France
| | - Eugénie Carletti
- From the Département de Toxicologie, Institut de Recherche Biomédicale des Armées-CRSSA, 38700 La Tronche, France
| | - Marcel Van der Schans
- the Research Group Diagnosis and Therapy, Business Unit Biological and Chemical Protection, TNO Defence, Security and Safety, 2288 GJ Rijswijk, The Netherlands, and
| | - Emilie Gillon
- From the Département de Toxicologie, Institut de Recherche Biomédicale des Armées-CRSSA, 38700 La Tronche, France
| | - Yvain Nicolet
- the Laboratoire de Cristallographie et Cristallogenèse des Protéines, Institut de Biologie Structurale, 38027 Grenoble, France
| | - Patrick Masson
- From the Département de Toxicologie, Institut de Recherche Biomédicale des Armées-CRSSA, 38700 La Tronche, France
| | - Maurice Goeldner
- the Laboratoire de Conception et Application de Molécules Bioactives, UMR 7199, Faculté de Pharmacie, 67400 Illkirch, France
| | - Daan Noort
- the Research Group Diagnosis and Therapy, Business Unit Biological and Chemical Protection, TNO Defence, Security and Safety, 2288 GJ Rijswijk, The Netherlands, and
| | - Florian Nachon
- From the Département de Toxicologie, Institut de Recherche Biomédicale des Armées-CRSSA, 38700 La Tronche, France
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32
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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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