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Thakur A, Patil P, Sharma A, Flora S. Advances in the Development of Reactivators for the Treatment of Organophosphorus Inhibited Cholinesterase. CURR ORG CHEM 2020. [DOI: 10.2174/1385272824999201020203544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Organophosphorus Compounds (OPCs) are used as pesticides to control pest, as
chemical weapons in military conflict and unfortunately in the terrorist attack. These compounds
are irreversible inhibitors of acetylcholinesterase, resulting in the accumulation of
acetylcholine that leads to severe health complications which may be ended with the death of
the victim. Current antidotes used for reactivation of organophosphorus inhibited acetylcholinesterase
(OP-AChE) are not able to cross the blood-brain barrier efficiently, therefore being
incapable to reactivate OP-AChE of the central nervous system. Due to limitations with
current antidotes, there is an urgent need for new effective antidotes that could be included in
the treatment regimen of OP poisoning. In this direction, comprehensive work has been done
to improve the permeability of existing antidotes using a variety of strategies that include
synthesis of oxime bonded to peripheral site binding moiety via an alkyl, aryl, or heteroatom-containing linker, synthesis
of sugar oximes, and prodrug of 2-PAM, incorporating fluorine and chlorine in the structure of charged oximes.
Other classes of compounds such as the mannich base, N-substituted hydroxyimino acetamide, alkylating
agents, have been investigated for reactivation of OP-AChE. This review comprises the development of various
classes of reactivators with the aim of either enhancing blood-brain permeability of existing antidotes or discovering
a new class of reactivators.
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Affiliation(s)
- Ashima Thakur
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Pooja Patil
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - Abha Sharma
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Raebareli, India
| | - S.J.S. Flora
- Pharmacology & Toxicology, National Institute of Pharmaceutical Education and Research, Raebareli, India
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Ying WB, Bae K, Ko NY, Kim SH, Ryu SG, Zhu J, Zhang R, Lee B, Lee KJ. Synthesis of poly[2-(3-butenyl)-2-oxazoline] with abundant carboxylic acid functional groups as a fiber-based sol–gel reaction supporter for catalytic applications. J IND ENG CHEM 2019. [DOI: 10.1016/j.jiec.2019.07.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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3
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Kim J, Malpani YR, Lee J, Shin JS, Han SB, Jung YS. Novel tacrine-pyridinium hybrid reactivators of organophosphorus-inhibited acetylcholinesterase: Synthesis, molecular docking, and in vitro reactivation study. Bioorg Med Chem Lett 2018; 28:3784-3786. [PMID: 30301674 DOI: 10.1016/j.bmcl.2018.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/07/2018] [Accepted: 10/03/2018] [Indexed: 12/11/2022]
Abstract
First-line medical treatment against nerve agents consists of co-administration of anticholinergic agents and oxime reactivators, which reactivate inhibited AChE. Pralidoxime, a commonly used oxime reactivator, is effective against some nerve agents but not against others; thus, new oxime reactivators are needed. Novel tacrine-pyridinium hybrid reactivators in which 4-pyridinealdoxime derivatives are connected to tacrine moieties by linear carbon chains of different lengths (C2-C7) were prepared (Scheme 1, 5a-f). Their binding affinities to electric eel AChE were tested because oximes can inhibit free AChE, and the highest AChE activity (95%, 92%, and 90%) was observed at 1 μM concentrations of the oximes (5a, 5b, and 5c, respectively). Based on their inhibitory affinities towards free AChE, 1 μM concentrations of the oxime derivatives (5) were used to examine reactivation of paraoxon-inhibited AChE. Reactivation ability increased as the carbon linker chains lengthened (n = 2-5), and 5c and 5d showed remarkable reactivation ability (41%) compared to that of 2-PAM (16%) and HI-6 (4%) against paraoxon-inhibited electric eel AChE at 1 μM concentrations. Molecular docking simulation showed that the most stable binding free energy was observed in 5c at 73.79 kcal⋅mol-1, and the binding mode of 5c is acceptable for the oxygen atom of oximate to attack the phosphorus atom of paraoxon and reactivate paraoxon-inhibited eel AChE model structure.
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Affiliation(s)
- Jinwoo Kim
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea
| | - Yashwardhan R Malpani
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea
| | - Jooyun Lee
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea
| | - Jin Soo Shin
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea
| | - Soo Bong Han
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea; Department of Medicinal and Pharmaceutical Chemistry, University of Science and Technology, 217 Gajeongro, Yuseong, Daejeon 34113, Republic of Korea
| | - Young-Sik Jung
- Division of Bio and Drug Discovery, Korea Research Institute of Chemical Technology, 141 Gajeongro, Yuseong, Daejeon 34114, Republic of Korea; Department of Medicinal and Pharmaceutical Chemistry, University of Science and Technology, 217 Gajeongro, Yuseong, Daejeon 34113, Republic of Korea.
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4
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Choi J, Moon DS, Ryu SG, Lee B, Lee KJ. Highly functionalized thermoplastic polyurethane from surface click reactions. J Appl Polym Sci 2018. [DOI: 10.1002/app.46519] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jihyun Choi
- Department of Applied Chemical Engineering, College of Engineering; Chungnam National University; Daejeon 305-764 South Korea
| | - Da Som Moon
- Department of Applied Chemical Engineering, College of Engineering; Chungnam National University; Daejeon 305-764 South Korea
| | - Sam Gon Ryu
- The 5th Research and Development Institute; Agency for Defense Development; Yuseong-Gu, Daejeon 305-600 South Korea
| | - Bumjae Lee
- Department of Applied Chemical Engineering, College of Engineering; Chungnam National University; Daejeon 305-764 South Korea
| | - Kyung Jin Lee
- Department of Applied Chemical Engineering, College of Engineering; Chungnam National University; Daejeon 305-764 South Korea
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Gorecki L, Korabecny J, Musilek K, Nepovimova E, Malinak D, Kucera T, Dolezal R, Jun D, Soukup O, Kuca K. Progress in acetylcholinesterase reactivators and in the treatment of organophosphorus intoxication: a patent review (2006-2016). Expert Opin Ther Pat 2017; 27:971-985. [PMID: 28569609 DOI: 10.1080/13543776.2017.1338275] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION organophosphorus compounds act as irreversible inhibitors of the vital enzyme acetylcholinesterase (AChE). this leads in the accumulation of acetylcholine (ACh) leading to cholinergic crisis and death. The main therapeutic approach is based on immediate administration of an ache reactivator as an antidote enabling recovery of the ache function. Areas covered: This review covers the development of AChE reactivators in order to introduce a new efficient drug that will overcome significant failures of common antidotes. Further options together with methods of detection are also discussed in order to assure a complete insight into the treatment of intoxication. Expert opinion: Since organophosphates belong to the most toxic chemical warfare agents, efficient antidotes are a matter of importance. The solution of how to limit the basic drawbacks of clinically used reactivators remained a spotlight for many researches worldwide. Recent strategies of the treatment of OP exposure bring us new possibilities which may overcome classic antidotes. The importance of detection of OP also has to be taken into consideration. Especially, with the fast spreading toxic effect when death can occur within minutes.
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Affiliation(s)
- Lukas Gorecki
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic.,b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic
| | - Jan Korabecny
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic.,b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic
| | - Kamil Musilek
- b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic.,c Faculty of Science, Department of Chemistry , University of Hradec Kralove , Hradec Kralove , Czech Republic
| | - Eugenie Nepovimova
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic.,b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic
| | - David Malinak
- b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic.,d Department of Physiology and Pathophysiology, Faculty of Medicine , University of Ostrava , Ostrava , Czech Republic
| | - Tomas Kucera
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic
| | - Rafael Dolezal
- b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic.,c Faculty of Science, Department of Chemistry , University of Hradec Kralove , Hradec Kralove , Czech Republic
| | - Daniel Jun
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic.,b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic
| | - Ondrej Soukup
- a Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences , University of Defence , Hradec Kralove , Czech Republic.,b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic
| | - Kamil Kuca
- b Biomedical Research Centre , University Hospital Hradec Kralove , Hradec Kralove , Czech Republic.,c Faculty of Science, Department of Chemistry , University of Hradec Kralove , Hradec Kralove , Czech Republic
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6
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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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Mathews TP, Carter MD, Johnson D, Isenberg SL, Graham LA, Thomas JD, Johnson RC. High-Confidence Qualitative Identification of Organophosphorus Nerve Agent Adducts to Human Butyrylcholinesterase. Anal Chem 2017; 89:1955-1964. [PMID: 28208252 DOI: 10.1021/acs.analchem.6b04441] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, a data-dependent, high-resolution tandem mass spectrometry (ddHRMS/MS) method capable of detecting all organophosphorus nerve agent (OPNA) adducts to human butyrylcholinesterase (BChE) was developed. After an exposure event, immunoprecipitation from blood with a BChE-specific antibody and digestion with pepsin produces a nine amino acid peptide containing the OPNA adduct. Signature product ions of this peptic BChE nonapeptide (FGES*AGAAS) offer a route to broadly screen for OPNA exposure. Taking this approach on an HRMS instrument identifies biomarkers, including unknowns, with high mass accuracy. Using a set of pooled human sera exposed to OPNAs as quality control (QC) materials, the developed method successfully identified precursor ions with <1 ppm and tied them to signature product ions with <5 ppm deviation from their chemical formulas. This high mass accuracy data from precursor and product ions, collected over 23 independent immunoprecipitation preparations, established method operating limits. QC data and experiments with 14 synthetic reference peptides indicated that reliable qualitative identification of biomarkers was possible for analytes >15 ng/mL. The developed method was applied to a convenience set of 96 unexposed serum samples and a blinded set of 80 samples treated with OPNAs. OPNA biomarkers were not observed in convenience set samples and no false positive or negative identifications were observed in blinded samples. All biomarkers in the blinded serum set >15 ng/mL were correctly identified. For the first time, this study reports a ddHRMS/MS method capable of complementing existing quantitative methodologies and suitable for identifying exposure to unknown organophosphorus agents.
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Affiliation(s)
- Thomas P Mathews
- Battelle at the Centers for Disease Control and Prevention , Atlanta, Georgia 30341, United States
| | - Melissa D Carter
- Centers for Disease Control and Prevention , National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia 30341, United States
| | - Darryl Johnson
- Oak Ridge Institute for Science and Education Fellow at the Centers for Disease Control and Prevention , Atlanta, Georgia 30341, United States
| | - Samantha L Isenberg
- Centers for Disease Control and Prevention , National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia 30341, United States
| | - Leigh Ann Graham
- Battelle at the Centers for Disease Control and Prevention , Atlanta, Georgia 30341, United States
| | - Jerry D Thomas
- Centers for Disease Control and Prevention , National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia 30341, United States
| | - Rudolph C Johnson
- Centers for Disease Control and Prevention , National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia 30341, United States
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8
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Ying WB, Kim S, Lee MW, Go NY, Jung H, Ryu SG, Lee B, Lee KJ. Toward a detoxification fabric against nerve gas agents: guanidine-functionalized poly[2-(3-butenyl)-2-oxazoline]/Nylon-6,6 nanofibers. RSC Adv 2017. [DOI: 10.1039/c7ra01278k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A novel guanidine-functionalized polymer, poly[2-(3-butenyl)-2-oxazoline] (PBuOxz), has been co-electrospun with Nylon-6,6 to form fibers that could be used for the decontamination of chemical warfare agents (CWAs).
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Affiliation(s)
- Wu Bin Ying
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
| | - Sohee Kim
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
| | - Min Woo Lee
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
| | - Na Yeong Go
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
| | | | - Sam Gon Ryu
- Agency for Defense Development (ADD)
- Daejeon
- Korea
| | - Bumjae Lee
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
| | - Kyung Jin Lee
- Department of Applied Chemical Engineering
- College of Engineering
- Chungnam National University
- Daejeon 305–764
- Korea
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9
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Graham LA, Johnson D, Carter MD, Stout EG, Erol HA, Isenberg SL, Mathews TP, Thomas JD, Johnson RC. A high-throughput UHPLC-MS/MS method for the quantification of five aged butyrylcholinesterase biomarkers from human exposure to organophosphorus nerve agents. Biomed Chromatogr 2016; 31. [PMID: 27572107 DOI: 10.1002/bmc.3830] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/04/2016] [Accepted: 08/24/2016] [Indexed: 11/11/2022]
Abstract
Organophosphorus nerve agents (OPNAs) are toxic compounds that are classified as prohibited Schedule 1 chemical weapons. In the body, OPNAs bind to butyrylcholinesterase (BChE) to form nerve agent adducts (OPNA-BChE). OPNA-BChE adducts can provide a reliable, long-term protein biomarker for assessing human exposure. A major challenge facing OPNA-BChE detection is hydrolysis (aging), which can continue to occur after a clinical specimen has been collected. During aging, the o-alkyl phosphoester bond hydrolyzes, and the specific identity of the nerve agent is lost. To better identify OPNA exposure events, a high-throughput method for the detection of five aged OPNA-BChE adducts was developed. This is the first diagnostic panel to allow for the simultaneous quantification of any Chemical Weapons Convention Schedule 1 OPNA by measuring the aged adducts methyl phosphonate, ethyl phosphonate, propyl phosphonate, ethyl phosphoryl, phosphoryl and unadducted BChE. The calibration range for all analytes is 2.00-250. ng/mL, which is consistent with similar methodologies used to detect unaged OPNA-BChE adducts. Each analytical run is 3 min, making the time to first unknown results, including calibration curve and quality controls, less than 1 h. Analysis of commercially purchased individual serum samples demonstrated no potential interferences with detection of aged OPNA-BChE adducts, and quantitative measurements of endogenous levels of BChE were similar to those previously reported in other OPNA-BChE adduct assays.
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Affiliation(s)
- Leigh Ann Graham
- Battelle at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Darryl Johnson
- Oak Ridge Institute for Science and Education Fellow at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Melissa D Carter
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Emily G Stout
- Oak Ridge Institute for Science and Education Fellow at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Huseyin A Erol
- Oak Ridge Institute for Science and Education Fellow at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Samantha L Isenberg
- Battelle at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Thomas P Mathews
- Battelle at the Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Jerry D Thomas
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Rudolph C Johnson
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Gorecki L, Korabecny J, Musilek K, Malinak D, Nepovimova E, Dolezal R, Jun D, Soukup O, Kuca K. SAR study to find optimal cholinesterase reactivator against organophosphorous nerve agents and pesticides. Arch Toxicol 2016; 90:2831-2859. [PMID: 27582056 DOI: 10.1007/s00204-016-1827-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 08/22/2016] [Indexed: 01/13/2023]
Abstract
Irreversible inhibition of acetylcholinesterase (AChE) by organophosphates leads to many failures in living organism and ultimately in death. Organophosphorus compounds developed as nerve agents such as tabun, sarin, soman, VX and others belong to the most toxic chemical warfare agents and are one of the biggest threats to the modern civilization. Moreover, misuse of nerve agents together with organophosphorus pesticides (e.g. malathion, paraoxon, chlorpyrifos, etc.) which are annually implicated in millions of intoxications and hundreds of thousand deaths reminds us of insufficient protection against these compounds. Basic treatments for these intoxications are based on immediate administration of atropine and acetylcholinesterase reactivators which are currently represented by mono- or bis-pyridinium aldoximes. However, these antidotes are not sufficient to ensure 100 % treatment efficacy even they are administered immediately after intoxication, and in general, they possess several drawbacks. Herein, we have reviewed new efforts leading to the development of novel reactivators and proposition of new promising strategies to design novel and effective antidotes. Structure-activity relationships and biological activities of recently proposed acetylcholinesterase reactivators are discussed and summarized. Among further modifications of known oximes, the main attention has been paid to dual binding site ligands of AChE as the current mainstream strategy. We have also discussed new chemical entities as potential replacement of oxime functional group.
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Affiliation(s)
- Lukas Gorecki
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic
| | - Jan Korabecny
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic
| | - Kamil Musilek
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic.,Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic
| | - David Malinak
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Physiology and Pathophysiology, Faculty of Medicine, University of Ostrava, Syllabova 19, 703 00, Ostrava, Czech Republic
| | - Eugenie Nepovimova
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic
| | - Rafael Dolezal
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic
| | - Daniel Jun
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic
| | - Ondrej Soukup
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.,Department of Toxicology and Military Pharmacy, Faculty of Military Health Sciences, University of Defence, Trebesska 1575, 500 01, Hradec Kralove, Czech Republic
| | - Kamil Kuca
- Biomedical Research Centre, University Hospital Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic. .,Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic.
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Lo R, Ganguly B. Can hydroxylamine be a more potent nucleophile for the reactivation of tabun-inhibited AChE than prototype oxime drugs? An answer derived from quantum chemical and steered molecular dynamics studies. MOLECULAR BIOSYSTEMS 2015; 10:2368-83. [PMID: 24964273 DOI: 10.1039/c4mb00083h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Organophosphorus nerve agents are highly toxic compounds which strongly inhibit acetylcholinesterase (AChE) in the blood and in the central nervous system (CNS). Tabun is one of the highly toxic organophosphorus (OP) compounds and is resistant to many oxime drugs formulated for the reactivation of AChE. The reactivation mechanism of tabun-conjugated AChE with various drugs has been examined with density functional theory and ab initio quantum chemical calculations. The presence of a lone-pair located on the amidic group resists the nucleophilic attack at the phosphorus center of the tabun-conjugated AChE. We have shown that the newly designed drug candidate N-(pyridin-2-yl)hydroxylamine, at the MP2/6-31+G*//M05-2X/6-31G* level in the aqueous phase with the polarizable continuum solvation model (PCM), is more effective in reactivating the tabun-conjugated AChE than typical oxime drugs. The rate determining activation barrier with N-(pyridin-2-yl)hydroxylamine was found to be ∼1.7 kcal mol(-1), which is 7.2 kcal mol(-1) lower than the charged oxime trimedoxime (one of the most efficient reactivators in tabun poisonings). The greater nucleophilicity index (ω(-)) and higher CHelpG charge of pyridinylhydroxylamine compared to TMB4 support this observation. Furthermore, we have also examined the reactivation process of tabun-inhibited AChE with some other bis-quaternary oxime drug candidates such as methoxime (MMB4) and obidoxime. The docking analysis suggests that charged bis-quaternary pyridinium oximes have greater binding affinity inside the active-site gorge of AChE compared to the neutral pyridinylhydroxylamine. The peripheral ligand attached to the neutral pyridinylhydroxylamine enhanced the binding with the aromatic residues in the active-site gorge of AChE through effective π-π interactions. Steered molecular dynamics (SMD) simulations have also been performed with the charged oxime (TMB4) and the neutral hydroxylamine. From protein-drug interaction parameters (rupture force profiles, hydrogen bonds, hydrophobic interactions), geometry and the orientation of the drug candidates, the hydroxylamine is suggested to orchestrate the reactivation process better than TMB4. Furthermore, the calculated log P values show the effective penetration of the neutral drug candidate through the blood-brain barrier. The toxicity measurements and the IC50 values (a measure of the intrinsic affinity toward AChE) suggest that the pyridinylhydroxylamine compound could have similar toxic behavior compared to the prototype oxime antidotes used for reactivation purposes. The newly designed pyridinylhydroxylamine drug candidate can be an effective antidote both kinetically and structurally to reactivate the tabun-inhibited enzyme.
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Affiliation(s)
- Rabindranath Lo
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, Gujarat, India-364 002.
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Mangas I, Taylor P, Vilanova E, Estévez J, França TCC, Komives E, Radić Z. Resolving pathways of interaction of mipafox and a sarin analog with human acetylcholinesterase by kinetics, mass spectrometry and molecular modeling approaches. Arch Toxicol 2015; 90:603-16. [PMID: 25743373 DOI: 10.1007/s00204-015-1481-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/12/2015] [Indexed: 01/07/2023]
Abstract
The hydroxyl oxygen of the catalytic triad serine in the active center of serine hydrolase acetylcholinesterase (AChE) attacks organophosphorus compounds (OPs) at the phosphorus atom to displace the primary leaving group and to form a covalent bond. Inhibited AChE can be reactivated by cleavage of the Ser-phosphorus bond either spontaneously or through a reaction with nucleophilic agents, such as oximes. At the same time, the inhibited AChE adduct can lose part of the molecule by progressive dealkylation over time in a process called aging. Reactivation of the aged enzyme has not yet been demonstrated. Here, our goal was to study oxime reactivation and aging reactions of human AChE inhibited by mipafox or a sarin analog (Flu-MPs, fluorescent methylphosphonate). Progressive reactivation was observed after Flu-MPs inhibition using oxime 2-PAM. However, no reactivation was observed after mipafox inhibition with 2-PAM or the more potent oximes used. A peptide fingerprinted mass spectrometry (MS) method, which clearly distinguished the peptide with the active serine (active center peptide, ACP) of the human AChE adducted with OPs, was developed by MALDI-TOF and MALDI-TOF/TOF. The ACP was detected with a diethyl-phosphorylated adduct after paraoxon inhibition, and with an isopropylmethyl-phosphonylated and a methyl-phosphonylated adduct after Flu-MPs inhibition and subsequent aging. Nevertheless, nonaged nonreactivated complexes were seen after mipafox inhibition and incubation with oximes, where MS data showed an ACP with an NN diisopropyl phosphoryl adduct. The kinetic experiments showed no reactivation of activity. The computational molecular model analysis of the mipafox-inhibited hAChE plots of energy versus distance between the atoms separated by dealkylation showed a high energy demand, thus little aging probability. However, with Flu-MPs and DFP, where aging was observed in our MS data and in previously published crystal structures, the energy demand calculated in modeling was lower and, consequently, aging appeared as a more likely reaction. We document here direct evidence for a phosphorylated hAChE refractory to oxime reactivation, although we observed no aging.
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Affiliation(s)
- I Mangas
- Unit of Toxicology and Chemical Safety, Institute of Bioengineering, University Miguel Hernandez of Elche, Alicante, Spain.
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, 92093, USA.
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense, Military Institute of Engineering, Rio de Janeiro, Brazil.
| | - P Taylor
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - E Vilanova
- Unit of Toxicology and Chemical Safety, Institute of Bioengineering, University Miguel Hernandez of Elche, Alicante, Spain
| | - J Estévez
- Unit of Toxicology and Chemical Safety, Institute of Bioengineering, University Miguel Hernandez of Elche, Alicante, Spain
| | - T C C França
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense, Military Institute of Engineering, Rio de Janeiro, Brazil
- Center for Basic and Applied Research, Faculty of Informatics and Management, University of Hradec Králové, Hradec Králové, Czech Republic
| | - E Komives
- Department of Chemistry-Biochemistry, University of California San Diego, La Jolla, CA, 92093, USA
| | - Z Radić
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, 92093, USA
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13
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Scheffel C, Thiermann H, Worek F. Effect of reversible ligands on oxime-induced reactivation of sarin- and cyclosarin-inhibited human acetylcholinesterase. Toxicol Lett 2015; 232:557-65. [DOI: 10.1016/j.toxlet.2014.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 12/11/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
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14
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Wu T, Zhao W, Yang Z, Gao H, Zhou Z. Temperature-controlled ultrasound- and vortex-assisted liquid-liquid microextraction combined with GC for the determination of the concentrations of organophosphorus pesticides in beverage samples. J Sep Sci 2013; 36:3918-25. [DOI: 10.1002/jssc.201300888] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Tong Wu
- Department of Applied Chemistry; China Agricultural University; Beijing China
| | - Wenting Zhao
- Department of Applied Chemistry; China Agricultural University; Beijing China
| | - Zhonghua Yang
- Department of Applied Chemistry; China Agricultural University; Beijing China
| | - Haixiang Gao
- Department of Applied Chemistry; China Agricultural University; Beijing China
| | - Zhiqiang Zhou
- Department of Applied Chemistry; China Agricultural University; Beijing China
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15
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Carter MD, Crow BS, Pantazides BG, Watson CM, Thomas JD, Blake TA, Johnson RC. Direct quantitation of methyl phosphonate adducts to human serum butyrylcholinesterase by immunomagnetic-UHPLC-MS/MS. Anal Chem 2013; 85:11106-11. [PMID: 24205842 DOI: 10.1021/ac4029714] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydrolysis of G- and V-series organophosphorus nerve agents (OPNAs) containing a phosphorus-methyl bond yields a methylphosphonic acid (MeP) product when adducted to human butyrylcholinesterase (BChE). The MeP adduct is considered a sign of "aging" and results in loss of the o-alkyl identifier specific to each nerve agent. After aging has occurred, common therapeutics such as oximes cannot reactivate the cholinesterase enzyme and relieve cholinergic inhibition. Until now, a direct, quantitative method for determination of the MeP adduct to BChE was unavailable. Aged adducts in serum samples were processed by immunomagnetic separation of BChE by antibody conjugated bead, isotope-dilution, pepsin digestion, followed by UHPLC separation and detection by conventional electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Ions were detected in selected reaction monitoring (SRM) mode, and transition m/z 874.3 → 778.3 was used for quantitation. The analytical response ratio was linearly proportional to the serum concentration of MeP-adducted peptide (MeP-P) over the nominal concentration range of 2.0-250 ng/mL, with a coefficient of determination of R(2) ≥ 0.997. Intrarun accuracy, expressed as %Relative Error (%RE), was ≤13.5%, 16.3%, and 3.20% at 2.0, 16, and 250 ng/mL, respectively; the corresponding precision expressed as %RSD was ≤11.9%, 6.15%, and 3.39%. Interday %RSD was ≤7.13%, 5.69%, and 1.91%. Recovery of MeP-P from serum was ≥68% across the validated concentration range, and contributions from matrix effects were minimal. The method provides a direct, quantitative measurement of MeP-P found in clinical samples suspected of nerve agent exposure and subjected to such post-sampling stresses as elevated temperature and extended shipping.
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Affiliation(s)
- Melissa D Carter
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention , Atlanta, Georgia 30341, United States
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16
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Chandar NB, Ganguly B. A first principles investigation of aging processes in soman conjugated AChE. Chem Biol Interact 2013; 204:185-90. [DOI: 10.1016/j.cbi.2013.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 05/10/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
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17
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Jiang W, Murashko EA, Dubrovskii YA, Podolskaya EP, Babakov VN, Mikler J, Nachon F, Masson P, Schopfer LM, Lockridge O. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of titanium oxide-enriched peptides for detection of aged organophosphorus adducts on human butyrylcholinesterase. Anal Biochem 2013; 439:132-41. [PMID: 23624322 DOI: 10.1016/j.ab.2013.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 10/26/2022]
Abstract
Exposure to nerve agents or organophosphorus (OP) pesticides can have life-threatening effects. Human plasma butyrylcholinesterase (BChE) inactivates these poisons by binding them to Ser198. After hours or days, these OP adducts acquire a negative charge by dealkylation in a process called aging. Our goal was to develop a method for enriching the aged adduct to facilitate detection of exposure. Human BChE inhibited by OP toxicants was incubated for 4 days to 6 years. Peptides produced by digestion with pepsin were enriched by binding to titanium oxide (TiO2) and analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. It was found that with two exceptions, all aged OP adducts in peptide FGES198AGAAS were enriched by binding to Titansphere tips. Cresyl saligenin phosphate yielded two types of aged adduct, cresylphosphate and phosphate, but only the phosphate adduct bound to Titansphere. The nerve agent VR yielded no aged adduct, supporting crystal structure findings that the VR adduct on BChE does not age. The irreversible nature of aged OP adducts was demonstrated by the finding that after 6 years at room temperature in sterile pH 7.0 buffer, the adducts were still detectable. It was concluded that TiO2 microcolumns can be used to enrich aged OP-modified BChE peptide.
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Affiliation(s)
- Wei Jiang
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA
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18
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Jiang W, Lockridge O. Detectable organophosphorus pesticide exposure in the blood of Nebraska and Iowa residents measured by mass spectrometry of butyrylcholinesterase adducts. Chem Biol Interact 2013; 203:91-5. [DOI: 10.1016/j.cbi.2012.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/03/2012] [Accepted: 09/05/2012] [Indexed: 11/26/2022]
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19
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Alemany LB, Malloy TB, Nunes MM, Zaibaq NG. Importance of cross-correlated relaxation in the spectra of simple organofluorine compounds: Spectral complexity of A3B3X spin systems compared to ABX spin systems. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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20
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Mercey G, Verdelet T, Renou J, Kliachyna M, Baati R, Nachon F, Jean L, Renard PY. Reactivators of acetylcholinesterase inhibited by organophosphorus nerve agents. Acc Chem Res 2012; 45:756-66. [PMID: 22360473 DOI: 10.1021/ar2002864] [Citation(s) in RCA: 245] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Since the September 11, 2001, terrorist attacks in the United States, the specter of a chemical threat against civilian populations has renewed research interest in chemical warfare agents, their mechanisms of action, and treatments that reverse their effects. In this Account, we focus specifically on organophosphorus nerve agents (OPNAs). Although some OPNAs are used as pest control, the most toxic chemicals in this class are used as chemical warfare agents in armed conflicts. The acute toxicity of OPNAs results from the irreversible inhibition of acetylcholinesterase (AChE, EC 3.1.1.7) via the formation of a covalent P-O bond at the serine hydroxyl group in the enzyme active site. AChE breaks down the neurotransmitter acetylcholine at neuronal synapses and neuromuscular junctions. The irreversible inhibition of AChE causes the neurotransmitter to accumulate in the synaptic cleft, leading to overstimulation of cholinergic receptors, seizures, respiratory arrest, and death. The current treatment for OPNA poisoning combines an antimuscarinic drug (e.g., atropine), an anticonvulsant drug (e.g., diazepam), and an AChE reactivator of the pyridinium aldoxime family (pralidoxime, trimedoxime, obidoxime, HI-6, HLö-7). Because of their high nucleophilicity, oximes can displace the phosphyl group from the catalytic serine, thus restoring the enzyme's catalytic activity. During 50 years of research in the reactivator field, researchers have synthesized and tested numerous structural modifications of monopyridinium oximes and bispyridinium oximes. In the past decade, medicinal chemists have focused their research on the more efficient bispyridinium reactivators, but all known reactivators have several drawbacks. First, due to their permanent positive charge, they do not cross the blood-brain barrier (BBB) efficiently and do not readily reactivate AChE in the central nervous system. Second, no single oxime is efficient against a wide variety of OPNAs. Third, oximes cannot reactivate "aged" AChE. This Account summarizes recent strategies for the development of AChE reactivators capable of crossing the BBB. The use of nanoparticulate transport and inhibition of P-glycoprotein efflux pumps improves BBB transport of these AChE reactivators. Chemical modifications that increased the lipophilicity of the pyridinium aldoximes, the addition of a fluorine atom and the replacement of a pyridyl ring with a dihydropyridyl moiety, enhances BBB permeability. The glycosylation of pyridine aldoximes facilitates increased BBB penetration via the GLUT-1 transport system. The development of novel uncharged reactivators that can move efficiently across the BBB represents one of the most promising of these new strategies.
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Affiliation(s)
- Guillaume Mercey
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Tristan Verdelet
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Julien Renou
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Maria Kliachyna
- Faculté de Pharmacie, Université de Strasbourg, CNRS UMR 7199, Laboratoire des Systèmes Chimiques Fonctionnels, 74 route du Rhin, BP 60024, 67401 Illkirch, France
| | - Rachid Baati
- Faculté de Pharmacie, Université de Strasbourg, CNRS UMR 7199, Laboratoire des Systèmes Chimiques Fonctionnels, 74 route du Rhin, BP 60024, 67401 Illkirch, France
| | - Florian Nachon
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, 24 Avenue des Maquis du Grésivaudan, BP87, 38702 La Tronche, France
| | - Ludovic Jean
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
| | - Pierre-Yves Renard
- Equipe de Chimie Bio-Organique, COBRA - CNRS UMR 6014 & FR 3038, Rue Lucien Tesnière, 76131 Mont-Saint-Aignan, France
- Université de Rouen, Place Emile Blondel, 76821, Mont-Saint-Aignan, France
- Institut Universitaire de France, 103 Boulevard Saint Michel, 75005 Paris, France
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21
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Probing O-dealkylation and deamination aging processes in tabun-conjugated AChE: a computational study. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1175-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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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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23
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Koskela H. Use of NMR techniques for toxic organophosphorus compound profiling. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:1365-81. [DOI: 10.1016/j.jchromb.2009.10.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Revised: 10/25/2009] [Accepted: 10/27/2009] [Indexed: 01/21/2023]
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24
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Nachon F, Carletti E, Worek F, Masson P. Aging mechanism of butyrylcholinesterase inhibited by an N-methyl analogue of tabun: implications of the trigonal-bipyramidal transition state rearrangement for the phosphylation or reactivation of cholinesterases. Chem Biol Interact 2010; 187:44-8. [PMID: 20381476 DOI: 10.1016/j.cbi.2010.03.053] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/19/2010] [Accepted: 03/31/2010] [Indexed: 11/28/2022]
Abstract
Cholinesterases are the main target of organophosphorus nerve agents (OPs). Their inhibition results in cholinergic syndrome and death. The enzymes are inhibited by phosphylation of the catalytic serine enzyme, but can be reactivated by oximes to some extent. However, phosphylated cholinesterases undergo a side reaction that progressively prevents their reactivatability. This unimolecular reaction, termed "aging", has been investigated for decades. It was shown that most OP-ChE conjugates aged by O-dealkylation of an alkoxy substituent of the phosphorus atom, a mechanism involving the stabilization of a transient carbocation. In this paper we present structural data supporting a substitution-based mechanism for aging of the huBChE conjugate of an N-mono-methyl analogue of tabun. This mechanism involves an adjacent nucleophilic attack followed by Berry pseudorotation. A similar adjacent attack and subsequent rearrangement of the transition state have been recently proposed for tabun phosphylation of AChE. We suggest that a similar mechanism is also possible for oxime reactivation of phosphylated cholinesterases. This opens new perspectives in terms of reactivator design.
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Affiliation(s)
- Florian Nachon
- Département de Toxicologie, Centre de Recherches du Service de Santé des Armées (CRSSA), 38702 La Tronche Cedex, France.
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25
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Sanson B, Nachon F, Colletier JP, Froment MT, Toker L, Greenblatt HM, Sussman JL, Ashani Y, Masson P, Silman I, Weik M. Crystallographic snapshots of nonaged and aged conjugates of soman with acetylcholinesterase, and of a ternary complex of the aged conjugate with pralidoxime. J Med Chem 2009; 52:7593-603. [PMID: 19642642 DOI: 10.1021/jm900433t] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organophosphate compounds (OP) are potent inhibitors of acetylcholinesterases (AChEs) and can cause lethal poisoning in humans. Inhibition of AChEs by the OP soman involves phosphonylation of the catalytic serine, and subsequent dealkylation produces a form known as the "aged" enzyme. The nonaged form can be reactivated to a certain extent by nucleophiles, such as pralidoxime (2-PAM), whereas aged forms of OP-inhibited AChEs are totally resistant to reactivation. Here, we solved the X-ray crystal structures of AChE from Torpedo californica (TcAChE) conjugated with soman before and after aging. The absolute configuration of the soman stereoisomer adduct in the nonaged conjugate is P(S)C(R). A structural reorientation of the catalytic His440 side chain was observed during the aging process. Furthermore, the crystal structure of the ternary complex of the aged conjugate with 2-PAM revealed that the orientation of the oxime function does not permit nucleophilic attack on the phosphorus atom, thus providing a plausible explanation for its failure to reactivate the aged soman/AChE conjugate. Together, these three crystal structures provide an experimental basis for the design of new reactivators.
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Affiliation(s)
- Benoît Sanson
- Laboratoire de Biophysique Moléculaire, Institut de Biologie Structurale Jean-Pierre Ebel, Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble, France
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26
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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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Chen L, Bromberg L, Schreuder-Gibson H, Walker J, Alan Hatton T, Rutledge GC. Chemical protection fabrics via surface oximation of electrospun polyacrylonitrile fiber mats. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b818639a] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Bromberg L, Schreuder-Gibson H, Creasy WR, McGarvey DJ, Fry RA, Hatton TA. Degradation of Chemical Warfare Agents by Reactive Polymers. Ind Eng Chem Res 2008. [DOI: 10.1021/ie801150y] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lev Bromberg
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
| | - Heidi Schreuder-Gibson
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
| | - William R. Creasy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
| | - David J. McGarvey
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
| | - Roderick A. Fry
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
| | - T. Alan Hatton
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S. Army Natick Soldier Research, Development & Engineering Center, Macromolecular Science Team, Natick, Massachusetts 01760-5020, Science Applications International Corporation, P.O. Box 68, Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010, and U.S. Army Edgewood Chemical and Biological Center, Research and Technology Directorate, Aberdeen Proving Ground-Edgewood Area,
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29
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dos Santos VMR, Sant'Anna CMR, Moya Borja GE, Chaaban A, Côrtes WS, DaCosta JBN. New bisphosphorothioates and bisphosphoroamidates: Synthesis, molecular modeling and determination of insecticide and toxicological profile. Bioorg Chem 2007; 35:68-81. [PMID: 17055030 DOI: 10.1016/j.bioorg.2006.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 08/30/2006] [Accepted: 08/30/2006] [Indexed: 11/28/2022]
Abstract
A series of new compounds, N,N'-bis(dialkylphosphoryl)diamines and S,S'-bis(dialkylphosphoryl)-1,3-propanedithiols were prepared by a Todd-Atherton like reaction of dialkylphosphites with symmetrical diamines and 1,3-propanedithiols in a biphasic system [F.R. Athertoon, H.T. Howard, A.R. Todd, J. Chem. Soc. (1948) 1106-1111; F.R. Athertoon, H.T. Openshaw, A.R. Todd, J. Chem. Soc. (1945) 660-663]. The structures were characterized by IR, 1H NMR, 13C NMR and mass spectrometry. Compounds with butoxy, isobutoxy and isopropoxy groups linked in the phosphorus atom showed the lowest LD50 values when tested against Musca domestica and Stomoxys calcitrans. The pharmacological and toxicological evaluation of N,N'-bis(diisobutylphosphoryl)-1,3-propylenediamine and S,S'-bis(diisobutylphosphoryl)-1,3-propanedithiol, which were very active against M. domestica and S. calcitrans, demonstrated that these compounds present no toxicological effects against mice in a concentration of 200mg/kg. An explanation for the observed activity profile is presented based on results obtained in a molecular modeling study with insect and mammalian acetylcholinesterase models.
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Affiliation(s)
- Viviane M R dos Santos
- Departamento de Química-ICE, Universidade Federal Rural do Rio de Janeiro (UFRRJ), km 7, BR 465, Seropédica, RJ 23890-000, Brazil
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30
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Majumdar D, Roszak S, Leszczynski J. Probing the Acetylcholinesterase Inhibition of Sarin: A Comparative Interaction Study of the Inhibitor and Acetylcholine with a Model Enzyme Cavity. J Phys Chem B 2006; 110:13597-607. [PMID: 16821887 DOI: 10.1021/jp061497n] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interaction energies have been estimated between sarin and a model enzyme cavity of acetylcholinesterase (ACHE) using the density functional and Møller-Plesset second-order perturbation (MP2) levels of theories. The calculated interaction energies have been compared with those of acetylcholine and the same model ACHE cavity. The ACHE...sarin and ACHE...acetylcholine (Ach) structures have been optimized using DFT based two-layer ONIOM hybrid calculations. The nature of interactions has been investigated in detail using an interaction energy partitioning technique. The effects of solvation on the interaction energies have also been taken into account. An inhibition mechanism during the uptake of sarin inside the ACHE cavity has been proposed from the comparison of the energetics of the ACHE...sarin and ACHE...Ach complexes.
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Affiliation(s)
- D Majumdar
- Computational Center for Molecular Structure and Interactions, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, USA
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31
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Paukku Y, Michalkova A, Majumdar D, Leszczynski J. Investigation on the low energy conformational surface of tabun to probe the role of its different conformers on biological activity. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.02.068] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Segev O, Columbus I, Ashani Y, Cohen Y. Probing the Molecular Interaction of Chymotrypsin with Organophosphorus Compounds by 31P Diffusion NMR in Aqueous Solutions. J Org Chem 2004; 70:309-14. [PMID: 15624938 DOI: 10.1021/jo0485942] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present study, we applied for the first time (31)P diffusion NMR to resolve different species obtained by the addition of organophosphorus compounds (OP) such as diisopropyl phosphorofluoridate (DFP) or 1-pyrenebutyl phosphorodichloridate (PBPDC) to alpha-chymotrypsin (Cht). (31)P diffusion NMR was used since the products of these reactions constitute a mixture of OP-covalent conjugates of the enzyme and OP-containing hydrolysis products that have noninformative (1)H NMR spectra. It was shown that the peak, attributed to the covalent native diisopropylphosphoryl-Cht (DIP-Cht) conjugate by chemical shift considerations, has a greater diffusion coefficient (D = (0.65 +/- 0.01) x 10(-5) cm(2) s(-1)) than expected from its molecular mass (approximately 25 kDa). This peak was therefore suggested to consist of at least two superimposed signals of diisopropyl phosphoryl (DIP) pools of high and low molecular weights that happen to have the same chemical shift. This conclusion was substantiated by the use of DMSO-d(6) that separated the overlapping signals. Diffusion measurements performed on the extensively dialyzed and unfolded DIP-Cht conjugate still resulted in a high diffusion coefficient ((0.30 +/- 0.05) x 10(-5) cm(2) s(-1)) relative to the assumed molecular mass. This observation was attributed to a dynamic dealkylation at the OP moiety (i.e., aging) that occurred during the relatively long diffusion measurements, where DIP-Cht was converted to the corresponding monoisopropyl phosphoryl Cht (MIP-Cht) conjugate. Homogeneous aged forms of OP-Cht were obtained by use of DFP and heat-induced dealkylation of DIP-Cht, and by PBPDC that provided the aged form via the hydrolysis of a P-Cl bond (PBP-Cht). The thermally stable aged conjugates enabled a reliable determination of the diffusion coefficients over several days of data acquisition, and the values found were (0.052 +/- 0.002) x 10(-5) cm(2) s(-1) and (0.054 +/-0.004) x 10(-5) cm(2) s(-1) for the MIP-Cht and the PBP-Cht adducts, respectively, values in the range expected for a species with a molecular weight of 25 kDa. The advantages and limitations of (31)P diffusion NMR in corroborating the type of species that prevail in such systems are briefly discussed.
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Affiliation(s)
- Omri Segev
- School of Chemistry, The Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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33
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George KM, Schule T, Sandoval LE, Jennings LL, Taylor P, Thompson CM. Differentiation between acetylcholinesterase and the organophosphate-inhibited form using antibodies and the correlation of antibody recognition with reactivation mechanism and rate. J Biol Chem 2003; 278:45512-8. [PMID: 12933813 DOI: 10.1074/jbc.m304781200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two types of polyclonal antibodies were generated from (a) a decapeptide sequence that includes the active site serine of acetylcholinesterase (anti-AChE10S) and (b) the identical decapeptide sequence phosphorylated at the active site serine of acetylcholinesterase (anti-AChE10SP). The anti-AChE10S antiserum was found to specifically recognize native, control, and vehicle-treated recombinant mouse AChE (rMoAChE) but did not recognize rMoAChE that was phosphorylated by the four organophosphate (OP) compounds tested. Conversely the anti-AChE10SP antiserum recognized phosphoserine rMoAChE that resulted from reaction with phosphorous oxychloride (POCl3) but did not recognize native or vehicle-treated rMoAChE. Anti-AChE10SP also did not recognize OP-AChE conjugates that resulted from the reaction of rMoAChE with other OP compounds that afford neutral or monoanionic phosphoserine groups thereby indicating a high specificity for a precise OP conjugate. Antisera recognition correlated well with the rates of enzyme inhibition, aging, and oxime-induced reactivation indicating these antisera can both quantify the extent and type of inhibition and also differentiate between select mechanisms of inhibition. The ability to discern mechanistic differences between native AChE and OP-AChE conjugates suggests that these antisera can be used to identify biomarkers of OP exposure in a mechanism-based approach.
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Affiliation(s)
- Kathleen M George
- Center for Environmental Health Sciences, The University of Montana, Missoula, Montana 59812, USA
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34
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Doorn JA, Schall M, Gage DA, Talley TT, Thompson CM, Richardson RJ. Identification of butyrylcholinesterase adducts after inhibition with isomalathion using mass spectrometry: difference in mechanism between (1R)- and (1S)-stereoisomers. Toxicol Appl Pharmacol 2001; 176:73-80. [PMID: 11601883 DOI: 10.1006/taap.2001.9279] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous kinetic studies found that butyrylcholinesterase (BChE) inhibited by (1R)-isomalathions readily reactivated, while enzyme inactivated by (1S)-isomers did not. This study tested the hypothesis that (1R)- and (1S)-isomers inhibit BChE by different mechanisms, yielding distinct adducts identifiable by peptide mass mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Equine BChE (EBChE) was inhibited to <10% of control activity with each isomer of isomalathion and the reference compound isoparathion methyl. Control and treated enzyme was digested with trypsin, and peptides were fractionated with HPLC. Separated and unseparated peptides were analyzed with MALDI-TOF-MS. Identity of an organophosphorus peptide adduct was confirmed by fragmentation using postsource decay analysis. EBChE inhibited by (1R)-isomalathions or (S)-isoparathion methyl readily reactivated after oxime treatment with 30-40% activity recovered. Enzyme inactivated by (1S)-isomalathions or (R)-isoparathion methyl recovered <2% and <5% activity, respectively, after oxime treatment. MALDI-TOF-MS analysis revealed that inhibition of EBChE by (1R)-isomalathions and (R)- or (S)-isoparathion methyl yielded O,S-dimethyl phosphate adducts. Enzyme inactivated by (1S)-isomalathions produced only O-methyl phosphate adduct. EBChE modified by (1R)-isomalathions or either enantiomer of isoparathion methyl yielded an O-methyl phosphate adduct as well. The results indicate that EBChE inhibition by (1R)-isomalathions proceeds with loss of diethyl thiosuccinate, but inactivation by (1S)-isomers occurs with loss of thiomethyl as the primary leaving group followed by rapid expulsion of diethyl thiosuccinate to yield an aged enzyme. Furthermore, the data suggest that aging of the O,S-dimethyl phosphate adduct occurs via an S(N)2 process with loss of thiomethyl.
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Affiliation(s)
- J A Doorn
- Toxicology Program, The University of Michigan, Ann Arbor, Michigan 48109, USA
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35
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Elhanany E, Ordentlich A, Dgany O, Kaplan D, Segall Y, Barak R, Velan B, Shafferman A. Resolving pathways of interaction of covalent inhibitors with the active site of acetylcholinesterases: MALDI-TOF/MS analysis of various nerve agent phosphyl adducts. Chem Res Toxicol 2001; 14:912-8. [PMID: 11453739 DOI: 10.1021/tx0100542] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding reaction pathways of phosphylation, reactivation, and "aging" of AChE with toxic organophosphate compounds is both a biochemical and a pharmacological challenge. Here we describe experiments which allowed to resolve some of the less well understood reaction pathways of phosphylation and "aging" of acetylcholinesterase (AChE) involving phosphoroamidates (P-N agents) such as tabun or the widely used pesticide methamidophos. Tryptic digests of phosphylated AChEs (from human and Torpedo californica), ZipTip peptide fractionation and matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF/MS) enabled reproducible signal enrichment of the isotopically resolved peaks of organophosphoroamidate conjugates of the AChE active site Ser peptides. For tabun and its hexadeuterio analogue, we find, as expected, that the two phosphoramidate adducts of the active site peptide differ by 6.05 mass units but following aging we find that the two corresponding phospho-peptides have identical molecular weights. We further show that the aging product of paraoxon-AChE adduct is identical to the aging product of the tabun-AChE conjugate. These results unequivocally demonstrate that the pathway of aging of tabun adducts of the human or the Torpedo californica AChEs proceeds through P-N bond scission. For methamidophos, we show that phosphylation of AChE involves elimination of the thiomethyl moiety and that the spontaneous reactivation of the resulting organophosphate adduct generates the phosphorus free AChE active site Ser-peptide.
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Affiliation(s)
- E Elhanany
- Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, 74100, Israel
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36
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Barak D, Ordentlich A, Kaplan D, Barak R, Mizrahi D, Kronman C, Segall Y, Velan B, Shafferman A. Evidence for P-N bond scission in phosphoroamidate nerve agent adducts of human acetylcholinesterase. Biochemistry 2000; 39:1156-61. [PMID: 10653663 DOI: 10.1021/bi992009n] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acetylcholinesterases (AChEs) form conjugates with certain highly toxic organophosphorus (OP) agents that become gradually resistant to reactivation. This phenomenon termed "aging" is a major factor limiting the effectiveness of therapy in certain cases of OP poisoning. While AChE adducts with phosphonates and phosphates are known to age through scission of the alkoxy C-O bond, the aging path for adducts with phosphoroamidates (P-N agents) like the nerve agent N,N-dimethylphosphonocyanoamidate (tabun) is not clear. Here we report that conjugates of tabun and of its butyl analogue (butyl-tabun) with the E202Q and F338A human AChEs (HuAChEs) age at similar rates to that of the wild-type enzyme. This is in marked contrast to the large effect of these substitutions on the aging of corresponding adducts with phosphates and phosphonates, suggesting that a different aging mechanism may be involved. Both tabun and butyl-tabun appear to be similarly accommodated in the active center, as suggested by molecular modeling and by kinetic studies of phosphylation and aging with a series of HuAChE mutants (E202Q, F338A, F295A, F297A, and F295L/F297V). Mass spectrometric analysis shows that HuAChE adduct formation with tabun and butyl-tabun occurs through loss of cyanide and that during the aging process both of these adducts show a mass decrease of 28 +/- 4 Da. Due to the nature of the alkoxy substituent, such mass decrease can be unequivocally assigned to loss of the dimethylamino group, at least for the butyl-tabun conjugate. This is the first demonstration that AChE adducts with toxic P-N agents can undergo aging through scission of the P-N bond.
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Affiliation(s)
- D Barak
- Departments of Organic Chemistry, Biochemistry and Molecular Biology, and Analytical Chemistry, Israel Institute for Biological Research, Ness-Ziona, 70450, Israel
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37
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Viragh C, Kovach IM, Pannell L. Small molecular products of dealkylation in soman-inhibited electric eel acetylcholinesterase. Biochemistry 1999; 38:9557-61. [PMID: 10423232 DOI: 10.1021/bi991112+] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Product analysis of dealkylation in P(S)C(S)-soman-inhibited electric eel acetylcholinesterase (AChE) by GC-MS using the selected ion monitoring mode has been carried out. The instrument was calibrated with pure standards of 2,3-dimethyl-1-butene and 2, 3-dimethyl-2-butene in the gas phase and methylene chloride extracts of 2,3-dimethyl-2-butanol and 3,3-dimethyl-2-butanol from the aqueous phase. The dealkylation in soman-inhibited AChE at pH 5.0 +/- 0.2 and 25 degrees C produces close to 40% alkenes and 50-60% 2, 3-dimethyl-2-butanol. No 3,3-dimethyl-2-butanol could be detected to provide direct evidence of the intervention of a secondary carbenium ion in the reaction path. All the products of the reaction originate from a tertiary carbenium ion. These findings are in good agreement with the results of Michel et al. [(1967) Arch. Biochem. Biophys. 121, 29], which were obtained by countercurrent distribution of tritium-labeled products and their identification by scintillation counting. The early experiments were performed with the mixture of the four soman diastereomers, all labeled with tritium in Calpha.
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Affiliation(s)
- C Viragh
- Department of Chemistry, The Catholic University of America, Washington, D.C. 20064, USA
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38
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Kovach IM, Enyedy EJ. Active-Site-Dependent Elimination of 4-Nitrophenol from 4-Nitrophenyl Alkylphosphonyl Serine Protease Adducts. J Am Chem Soc 1998. [DOI: 10.1021/ja9728031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ildiko M. Kovach
- Contribution from the Department of Chemistry, The Catholic University of America, Washington, D.C. 20064
| | - Edith J. Enyedy
- Contribution from the Department of Chemistry, The Catholic University of America, Washington, D.C. 20064
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39
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Masson P, Fortier PL, Albaret C, Froment MT, Bartels CF, Lockridge O. Aging of di-isopropyl-phosphorylated human butyrylcholinesterase. Biochem J 1997; 327 ( Pt 2):601-7. [PMID: 9359435 PMCID: PMC1218835 DOI: 10.1042/bj3270601] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Organophosphate-inhibited cholinesterases can be reactivated by nucleophilic compounds. Sometimes phosphylated (phosphorylated or phosphonylated) cholinesterases become progressively refractory to reactivation; this can result from different reactions. The most frequent process, termed 'aging', involves the dealkylation of an alkoxy group on the phosphyl moiety through a carbocation mechanism. In attempting to determine the amino acid residues involved in the aging of butyrylcholinesterase (BuChE), the human BuChE gene was mutated at several positions corresponding to residues located at the rim of the active site gorge and in the vicinity of the active site. Mutant enzymes were expressed in Chinese hamster ovary cells. Wild-type BuChE and mutants were inhibited by di-isopropylfluorophosphate at pH 8.0 and 25 degrees C. Di-isopropyl-phosphorylated enzymes were incubated with the nucleophilic oxime 2-pyridine aldoxime methiodide and their reactivatability was determined. Reactivatability was expressed by the first-order rate constant of aging and/or the half-life of aging (t12). The t12 was found to be of the order of 60 min for wild-type BuChE. Mutations on Glu-197 increased t12 60-fold. Mutation W82A increased t12 13-fold. Mutation D70G increased t12 8-fold. Mutations in the vicinity of the active site serine residue had either moderate or no effect on aging; t12 was doubled for F329C and F329A, increased only 4-fold for the double mutant A328G+F329S, and no change was observed for the A328G mutant, indicating that the isopropoxy chain to be dealkylated does not directly interact with Ala-328 and Phe-329. These results were interpreted by molecular modelling of di-isopropylphosphorylated wild-type and mutant enzymes. Molecular dynamics simulations indicated that the isopropyl chain that is lost interacted with Trp-82, suggesting that Trp-82 has a role in stabilizing the carbonium ion that is released in the dealkylation step. This study emphasized the important role of the Glu-197 carboxylate in stabilizing the developing carbocation, and the allosteric control of the dealkylation reaction by Asp-70. Indeed, although Asp-70 does not interact with the phosphoryl moiety, mutation D70G affects the rate of aging. This indirect control was interpreted in terms of change in the conformational state of Trp-82 owing to internal motions of the Omega loop (Cys-65-Cys-92) in the mutant enzyme.
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Affiliation(s)
- P Masson
- Centre de Recherches du Service de Santé des Armées, Unité de Biochimie, 24 avenue des Maquis du Grésivaudan, B.P. 87, 38702 La Tronche Cédex, France
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40
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Saxena A, Maxwell DM, Quinn DM, Radić Z, Taylor P, Doctor BP. Mutant acetylcholinesterases as potential detoxification agents for organophosphate poisoning. Biochem Pharmacol 1997; 54:269-74. [PMID: 9271331 DOI: 10.1016/s0006-2952(97)00180-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It has been demonstrated that cholinesterases (ChEs) are an effective mode of pretreatment to prevent organophosphate (OP) toxicity in mice and rhesus monkeys. The efficacy of ChE as a bioscavenger of OP can be enhanced by combining enzyme pretreatment with oxime reactivation, since the scavenging capacity extends beyond a stoichiometric ratio of ChE to OP. Aging has proven to be a major barrier to achieving oxime reactivation of acetylcholinesterase (AChE) inhibited by the more potent OPs. To further increase the stoichiometry of OP to ChE required, we have sought AChE mutants that are more easily reactivated than wild-type enzyme. Substitution of glutamine for glutamate (E199) located at the amino-terminal to the active-site serine (S200) in Torpedo AChE generated an enzyme largely resistant to aging. Here we report the effect of the corresponding mutation on the rate of inhibition, reactivation by 1-(2-hydroxyiminomethyl-1-pyridinium)-1(4-carboxyaminopyridinium)- dimethyl ether hydrochloride (HI-6), and aging of mouse AChE inhibited by C(+)P(-)- and C(-)P(-)-epimers of soman. The E202 to Q mutation decreased the affinity of soman for AChE, slowed the reactivation of soman-inhibited AChE by HI-6, and decreased the aging of mutant AChE. These effects were more pronounced with C(-)P(-)-soman than with C(+)P(-)-soman. In vitro detoxification of soman and sarin by wild-type and E202Q AChE in the presence of 2 mM HI-6 showed that, E202Q AChE was 2-3 times more effective in detoxifying soman and sarin than wild-type AChE. These studies show that these recombinant DNA-derived AChEs are a great improvement over wild-type AChE as bioscavengers. They can be used to develop effective methods for the safe disposal of stored OP nerve agents and potential candidates for pre- or post-exposure treatment for OP toxicity.
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Affiliation(s)
- A Saxena
- Walter Reed Army Institute of Research, Washington, DC 20307, U.S.A
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41
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Barak R, Ordentlich A, Barak D, Fischer M, Benschop HP, De Jong LP, Segall Y, Velan B, Shafferman A. Direct determination of the chemical composition of acetylcholinesterase phosphonylation products utilizing electrospray-ionization mass spectrometry. FEBS Lett 1997; 407:347-52. [PMID: 9175882 DOI: 10.1016/s0014-5793(97)00375-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
While non-reactivability of cholinesterases from their phosphyl conjugates (aging) is attributed to an unimolecular process involving loss of alkyl group from the phosphyl moiety, no conclusive evidence is available that this is the only reaction path and involvement of other post-inhibitory processes cannot be ruled out. To address this issue, molecular masses of the bacterially expressed recombinant human acetylcholinesterase and of its conjugates with a homologous series of alkyl methylphosphonofluoridates, were measured by electrospray-ionization mass spectrometry (ESI-MS). The measured mass of the free enzyme was 64,700 Da (calculated 64,695 Da) and those of the methylphosphono-HuAChE adducts, bearing isopropyl, isobutyl, 1,2-dimethylpropyl and 1,2,2-trimethylpropyl substituents, were 64,820, 64,840, 64,852 and 64,860 Da, respectively. These values reflect both the addition of the phosphonyl moiety and the gradual mass increase due to branching of the alkoxy substituent. The composition of these adducts change with time to yield a common product with molecular mass of 64,780 Da which is consistent with dealkylation of the phosphonyl moieties. Furthermore, in the case of 1,2-dimethylpropyl methylphosphono-HuAChE, the change in the molecular mass and the kinetics of non-reactivability appear to occur in parallel indicating that dealkylation is indeed the predominant molecular transformation leading to 'aging' of phosphonyl-AChE adducts.
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Affiliation(s)
- R Barak
- Department of Analytical Chemistry, Israel Institute for Biological Research, Ness-Ziona
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42
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Shafferman A, Ordentlich A, Barak D, Stein D, Ariel N, Velan B. Aging of phosphylated human acetylcholinesterase: catalytic processes mediated by aromatic and polar residues of the active centre. Biochem J 1996; 318 ( Pt 3):833-40. [PMID: 8836126 PMCID: PMC1217693 DOI: 10.1042/bj3180833] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have examined the effects of 11 substitutions of active centre gorge residues of human acetylcholinesterase (HuAChE) on the rates of phosphonylation by 1,2,2-trimethylpropyl methyl-phosphonofluoridate (soman) and the aging of the resulting conjugates. The rates of phosphonylation were reduced to as little as one-seventieth, mainly in mutants of the hydrogen-bond network (Glu-202, Glu-450, Tyr-133). These recombinant enzymes as well as the F338A, W86A, W86F and D74N mutant HuAChEs varied in their resistance to aging (15-3300-fold relative to the wild type). The most dramatic resistance to aging was observed for the phosphonyl conjugate of the mutant W86A enzyme (1850-3300-fold relative to the wild type). It is proposed that Trp-86 contributes to the aging process by stabilizing the evolving carbonium ion on the 1,2,2-trimethylpropyl moiety, via charge-pi interaction. The rate-enhancing effect of Trp-86 provides a rationale for the unique facility of aging in soman-inhibited cholinesterases, compared with the corresponding conjugates in other serine hydrolases. Replacements of Glu-202 by aspartic acid, glutamine or alanine residues resulted in a similar (1/130-1/300) decrease of the rates of aging. A comparable decrease was also observed for the conjugate of the F338A mutant. These results, and the similar pH dependence of aging rates for the wild-type and E202Q and F338A mutant HuAChEs, indicate that Glu-202 is not involved in proton transfer to the phosphonyl moiety. On the basis of these findings and of molecular modelling we suggest that Glu-202 and Phe-338 contribute to the aging process by stabilizing the imidazolium of the catalytic triad His-447 via charge-charge and charge-pi interactions respectively, thereby facilitating an oxonium formation on the phosphonyl moiety.
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Affiliation(s)
- A Shafferman
- Department of Biochemistry and Molecular Biology, Israel Institute for Biological Research, Ness-Ziona, Israel
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43
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Aslanian D, Gróf P, Renault F, Masson P. Raman spectroscopic study of conjugates of butyrylcholinesterase with organophosphates. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1249:37-44. [PMID: 7766682 DOI: 10.1016/0167-4838(95)00035-s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Raman spectra of human butyrylcholinesterase (BuChE; E.C. 3.1.1.8) were analyzed in the native state and after conjugation with organophosphates (soman, DFP and paraoxon). The secondary structure of the native BuChE in Tris-HCl buffer (pH 7.5), determined from analysis of the amide I polypeptide vibration band, indicates 47% alpha-helices, 26% beta-sheets, 16% turns and 12% undefined structure. We obtained the same values for paraoxon-phosphorylated BuChE, but 39% helical structure, 31% beta-sheets, 17% turns and 13% undefined structure for 'aged' DFP-BuChE conjugates and 36% helical structure, 34% beta-sheets, 20% turns and 10% undefined structure for 'aged' soman-BuChE conjugates. The approximately 10% decrease of alpha-helical structure observed upon phosphorylation by DFP and phosphonylation by soman, probably corresponds to the 'aging' process, which does not take place in the case of paraoxon. Considerable differences have been observed between native, paraoxon inhibited and 'aged' BuChE in aromatic ring vibrations, suggesting that the dealkylation of organophosphate conjugates modifies the environment or the interactions of aromatic amino-acid residues. In the aliphatic side chains an increase of the number of gauche configurations has been observed in 'aged' DFP-BuChE and soman-BuChE.
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Affiliation(s)
- D Aslanian
- Laboratoire de Physique des Solides, Associé au CNRS, Université Pierre et Marie Curie, Paris, France
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Ashani Y, Radić Z, Tsigelny I, Vellom DC, Pickering NA, Quinn DM, Doctor BP, Taylor P. Amino acid residues controlling reactivation of organophosphonyl conjugates of acetylcholinesterase by mono- and bisquaternary oximes. J Biol Chem 1995; 270:6370-80. [PMID: 7890775 DOI: 10.1074/jbc.270.11.6370] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Single and multiple site mutants of recombinant mouse acetylcholinesterase (rMoAChE) were inhibited with racemic 7-(methylethoxyphosphinyloxy)-1-methylquinolinium iodide (MEPQ) and the resulting mixture of two enantiomers, CH3PR,S(O)(OC2H5)-AChE(EMPR,S-AChE), were subjected to reactivation with 2-(hydroxyiminomethyl)-1-methylpyridinium methanesulfonate (P2S) and 1-(2'-hydroxyiminomethyl-1'-pyridinium)-3-(4"-carbamoyl-1"- pyridinium)-2-oxapropane dichloride (HI-6). Kinetic analysis of the reactivation profiles revealed biphasic behavior with an approximate 1:1 ratio of two presumed reactivatable enantiomeric components. Equilibrium dissociation and kinetic rate constants for reactivation of site-specific mutant enzymes were compared with those obtained for wild-type rMoAChE, tissue-derived Torpedo AChE and human plasma butyrylcholinesterase. Substitution of key amino acid residues at the entrance to the active-site gorge (Trp-286, Tyr-124, Tyr-72, and Asp-74) had a greater influence on the reactivation kinetics of the bisquaternary reactivator HI-6 compared with the monoquaternary reactivator P2S. Replacement of Phe-295 by Leu enhanced reactivation by HI-6 but not by P2S. Of residues forming the choline-binding subsite, the E202Q mutation had a dominant influence where reactivation by both oximes was decreased 16- to 33-fold. Residues Trp-86 and Tyr-337 in this subsite showed little involvement. These kinetic findings, together with energy minimization of the oxime complex with the phosphonylated enzyme, provide a model for differences in the reactivation potencies of P2S and HI-6. The two kinetic components of oxime reactivation of MEPQ-inhibited AChEs arise from the chirality of O-ethyl methylphosphonyl moieties conjugated with Ser-203 and may be attributable to the relative stability of the phosphonyl oxygen of the two enantiomers in the oxyanion hole.
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Affiliation(s)
- Y Ashani
- Division of Biochemistry, Walter Reed Army Institute of Research, Washington, D.C. 20307-5100
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