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Jaiswal S, Singh B, Dhingra I, Joshi A, Kodgire P. Bioremediation and bioscavenging for elimination of organophosphorus threats: An approach using enzymatic advancements. ENVIRONMENTAL RESEARCH 2024; 252:118888. [PMID: 38599448 DOI: 10.1016/j.envres.2024.118888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/06/2024] [Accepted: 04/05/2024] [Indexed: 04/12/2024]
Abstract
Organophosphorus compounds (OP) are highly toxic pesticides and nerve agents widely used in agriculture and chemical warfare. The extensive use of these chemicals has severe environmental implications, such as contamination of soil, water bodies, and food chains, thus endangering ecosystems and biodiversity. Plants absorb pesticide residues, which then enter the food chain and accumulate in the body fat of both humans and animals. Numerous human cases of OP poisoning have been linked to both acute and long-term exposure to these toxic OP compounds. These compounds inhibit the action of the acetylcholinesterase enzyme (AChE) by phosphorylation, which prevents the breakdown of acetylcholine (ACh) neurotransmitter into choline and acetate. Thus, it becomes vital to cleanse the environment from these chemicals utilizing various physical, chemical, and biological methods. Biological methods encompassing bioremediation using immobilized microbes and enzymes have emerged as environment-friendly and cost-effective approaches for pesticide removal. Cell/enzyme immobilized systems offer higher stability, reusability, and ease of product recovery, making them ideal tools for OP bioremediation. Interestingly, enzymatic bioscavengers (stoichiometric, pseudo-catalytic, and catalytic) play a vital role in detoxifying pesticides from the human body. Catalytic bioscavenging enzymes such as Organophosphate Hydrolase, Organophosphorus acid anhydrolase, and Paraoxonase 1 show high degradation efficiency within the animal body as well as in the environment. Moreover, these enzymes can also be employed to decontaminate pesticides from food, ensuring food safety and thus minimizing human exposure. This review aims to provide insights to potential collaborators in research organizations, government bodies, and industries to bring advancements in the field of bioremediation and bioscavenging technologies for the mitigation of OP-induced health hazards.
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Affiliation(s)
- Surbhi Jaiswal
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Simrol, Khandwa Road, Indore, 453552, India
| | - Brijeshwar Singh
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Simrol, Khandwa Road, Indore, 453552, India
| | - Isha Dhingra
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Simrol, Khandwa Road, Indore, 453552, India
| | - Abhijeet Joshi
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Simrol, Khandwa Road, Indore, 453552, India.
| | - Prashant Kodgire
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Simrol, Khandwa Road, Indore, 453552, India.
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Azman AA, Muhd Noor ND, Leow ATC, Mohd Noor SA, Mohamad Ali MS. Identification and characterization of a promiscuous metallohydrolase in metallo-β-lactamase superfamily from a locally isolated organophosphate-degrading Bacillus sp. strain S3wahi. Int J Biol Macromol 2024; 271:132395. [PMID: 38761915 DOI: 10.1016/j.ijbiomac.2024.132395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 04/23/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
In this present study, characteristics and structure-function relationship of an organophosphate-degrading enzyme from Bacillus sp. S3wahi were described. S3wahi metallohydrolase, designated as S3wahi-MH (probable metallohydrolase YqjP), featured the conserved αβ/βα metallo-β-lactamase-fold (MBL-fold) domain and a zinc bimetal at its catalytic site. The metal binding site of S3wahi-MH also preserves the H-X-H-X-D-H motif, consisting of specific amino acids at Zn1 (Asp69, His70, Asp182, and His230) and Zn2 (His65, His67, and His137). The multifunctionality of S3wahi-MH was demonstrated through a steady-state kinetic study, revealing its highest binding affinity (KM) and catalytic efficiency (kcat/KM) for OP compound, paraoxon, with values of 8.09 × 10-6 M and 4.94 × 105 M-1 s-1, respectively. Using OP compound, paraoxon, as S3wahi-MH native substrate, S3wahi-MH exhibited remarkable stability over a broad temperature range, 20 °C - 60 °C and a broad pH tolerance, pH 6-10. Corresponded to S3wahi-MH thermal stability characterization, the estimated melting temperature (Tm) was found to be 72.12 °C. S3wahi-MH was also characterized with optimum catalytic activity at 30 °C and pH 8. Additionally, the activity of purified S3wahi-MH was greatly enhanced in the presence of 1 mM and 5 mM of manganese (Mn2+), showing relative activities of 1323.68 % and 2073.68 %, respectively. The activity of S3wahi-MH was also enhanced in the presence of DMSO and DMF, showing relative activities of 270.37 % and 307.41 %, respectively. The purified S3wahi-MH retained >60 % residual activity after exposure to non-ionic Tween series surfactants. Nevertheless, the catalytic activity of S3wahi-MH was severely impacted by the treatment of SDS, even at low concentrations. Considering its enzymatic properties and promiscuity, S3wahi-MH emerges as a promising candidate as a bioremediation tool in wide industrial applications, including agriculture industry.
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Affiliation(s)
- Ameera Aisyah Azman
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia
| | - Noor Dina Muhd Noor
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia
| | - Adam Thean Chor Leow
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia
| | - Siti Aminah Mohd Noor
- Center for Defence Foundation Studies, National Defence University of Malaysia, Kem Perdana Sungai Besi, Kuala Lumpur 57000, Malaysia
| | - Mohd Shukuri Mohamad Ali
- Enzyme and Microbial Technology Research Center, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; Department of Biochemistry, Faculty of Biotechnology and Biomolecular Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia.
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Job L, Köhler A, Testanera M, Escher B, Worek F, Skerra A. Engineering of a phosphotriesterase with improved stability and enhanced activity for detoxification of the pesticide metabolite malaoxon. Protein Eng Des Sel 2023; 36:gzad020. [PMID: 37941439 DOI: 10.1093/protein/gzad020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/30/2023] [Accepted: 11/03/2023] [Indexed: 11/10/2023] Open
Abstract
Organophosphorus (OP) pesticides are still widely applied but pose a severe toxicological threat if misused. For in vivo detoxification, the application of hydrolytic enzymes potentially offers a promising treatment. A well-studied example is the phosphotriesterase of Brevundimonas diminuta (BdPTE). Whereas wild-type BdPTE can hydrolyse pesticides like paraoxon, chlorpyrifos-oxon and mevinphos with high catalytic efficiencies, kcat/KM >2 × 107 M-1 min-1, degradation of malaoxon is unsatisfactory (kcat/KM ≈ 1 × 104 M-1 min-1). Here, we report the rational engineering of BdPTE mutants with improved properties and their efficient production in Escherichia coli. As result, the mutant BdPTE(VRNVVLARY) exhibits 37-fold faster malaoxon hydrolysis (kcat/KM = 4.6 × 105 M-1 min-1), together with enhanced expression yield, improved thermal stability and reduced susceptibility to oxidation. Therefore, this BdPTE mutant constitutes a powerful candidate to develop a biocatalytic antidote for the detoxification of this common pesticide metabolite as well as related OP compounds.
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Affiliation(s)
- Laura Job
- Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
| | - Anja Köhler
- Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
- Institut für Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstr, 11, 80937 München, Germany
| | - Mauricio Testanera
- Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
| | - Benjamin Escher
- Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
| | - Franz Worek
- Institut für Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstr, 11, 80937 München, Germany
| | - Arne Skerra
- Lehrstuhl für Biologische Chemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
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Stigler L, Köhler A, Koller M, Job L, Escher B, Potschka H, Thiermann H, Skerra A, Worek F, Wille T. Post-VX exposure treatment of rats with engineered phosphotriesterases. Arch Toxicol 2021; 96:571-583. [PMID: 34962578 PMCID: PMC8837561 DOI: 10.1007/s00204-021-03199-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/09/2021] [Indexed: 12/05/2022]
Abstract
The biologically stable and highly toxic organophosphorus nerve agent (OP) VX poses a major health threat. Standard medical therapy, consisting of reactivators and competitive muscarinic receptor antagonists, is insufficient. Recently, two engineered mutants of the Brevundimonas diminuta phosphotriesterase (PTE) with enhanced catalytic efficiency (kcat/KM = 21 to 38 × 106 M−1 min−1) towards VX and a preferential hydrolysis of the more toxic P(−) enantiomer were described: PTE-C23(R152E)-PAS(100)-10-2-C3(I106A/C59V/C227V/E71K)-PAS(200) (PTE-2), a single-chain bispecific enzyme with a PAS linker and tag having enlarged substrate spectrum, and 10-2-C3(C59V/C227V)-PAS(200) (PTE-3), a stabilized homodimeric enzyme with a double PASylation tag (PAS-tag) to reduce plasma clearance. To assess in vivo efficacy, these engineered enzymes were tested in an anesthetized rat model post-VX exposure (~ 2LD50) in comparison with the recombinant wild-type PTE (PTE-1), dosed at 1.0 mg kg−1 i.v.: PTE-2 dosed at 1.3 mg kg−1 i.v. (PTE-2.1) and 2.6 mg kg−1 i.v. (PTE-2.2) and PTE-3 at 1.4 mg kg−1 i.v. Injection of the mutants PTE-2.2 and PTE-3, 5 min after s.c. VX exposure, ensured survival and prevented severe signs of a cholinergic crisis. Inhibition of erythrocyte acetylcholinesterase (AChE) could not be prevented. However, medulla oblongata and diaphragm AChE activity was partially preserved. All animals treated with the wild-type enzyme, PTE-1, showed severe cholinergic signs and died during the observation period of 180 min. PTE-2.1 resulted in the survival of all animals, yet accompanied by severe signs of OP poisoning. This study demonstrates for the first time efficient detoxification in vivo achieved with low doses of heterodimeric PTE-2 as well as PTE-3 and indicates the suitability of these engineered enzymes for the development of highly effective catalytic scavengers directed against VX.
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Affiliation(s)
- Lisa Stigler
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany
| | - Anja Köhler
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany.,Chair of Biological Chemistry, Technical University of Munich, Emil-Erlenmeyer-Forum 5, 85354, Freising, Germany
| | - Marianne Koller
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany
| | - Laura Job
- Chair of Biological Chemistry, Technical University of Munich, Emil-Erlenmeyer-Forum 5, 85354, Freising, Germany
| | - Benjamin Escher
- Chair of Biological Chemistry, Technical University of Munich, Emil-Erlenmeyer-Forum 5, 85354, Freising, Germany
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University Munich, Königinstraße 16, 80539, Munich, Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany
| | - Arne Skerra
- Chair of Biological Chemistry, Technical University of Munich, Emil-Erlenmeyer-Forum 5, 85354, Freising, Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937, Munich, Germany.
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Overview of a bioremediation tool: organophosphorus hydrolase and its significant application in the food, environmental, and therapy fields. Appl Microbiol Biotechnol 2021; 105:8241-8253. [PMID: 34665276 DOI: 10.1007/s00253-021-11633-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 12/14/2022]
Abstract
In the past decades, the organophosphorus compounds had been widely used in the environment and food industries as pesticides. Owing to the life-threatening and long-lasting problems of organophosphorus insecticide (OPs), an effective detection and removal of OPs have garnered growing attention both in the scientific and practical fields in recent years. Bacterial organophosphorus hydrolases (OPHs) have been extensively studied due to their high specific activity against OPs. OPH could efficiently hydrolyze a broad range of substrates both including the OP pesticides and some nerve agents, suggesting a great potential for the remediation of OPs. In this review, the microbial identification, molecular modification, and practical application of OPHs were comprehensively discussed.Key points• Microbial OPH is a significant bioremediation tool against OPs.• Identification and molecular modification of OPH was discussed in detail.• The applications of OPH in food, environmental, and therapy fields are presented.
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Köhler A, Escher B, Job L, Koller M, Thiermann H, Skerra A, Worek F. Catalytic activity and stereoselectivity of engineered phosphotriesterases towards structurally different nerve agents in vitro. Arch Toxicol 2021; 95:2815-2823. [PMID: 34160649 PMCID: PMC8298220 DOI: 10.1007/s00204-021-03094-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/15/2021] [Indexed: 12/20/2022]
Abstract
Highly toxic organophosphorus nerve agents, especially the extremely stable and persistent V-type agents such as VX, still pose a threat to the human population and require effective medical countermeasures. Engineered mutants of the Brevundimonas diminuta phosphotriesterase (BdPTE) exhibit enhanced catalytic activities and have demonstrated detoxification in animal models, however, substrate specificity and fast plasma clearance limit their medical applicability. To allow better assessment of their substrate profiles, we have thoroughly investigated the catalytic efficacies of five BdPTE mutants with 17 different nerve agents using an AChE inhibition assay. In addition, we studied one BdPTE version that was fused with structurally disordered PAS polypeptides to enable delayed plasma clearance and one bispecific BdPTE with broadened substrate spectrum composed of two functionally distinct subunits connected by a PAS linker. Measured kcat/KM values were as high as 6.5 and 1.5 × 108 M-1 min-1 with G- and V-agents, respectively. Furthermore, the stereoselective degradation of VX enantiomers by the PASylated BdPTE-4 and the bispecific BdPTE-7 were investigated by chiral LC-MS/MS, resulting in a several fold faster hydrolysis of the more toxic P(-) VX stereoisomer compared to P(+) VX. In conclusion, the newly developed enzymes BdPTE-4 and BdPTE-7 have shown high catalytic efficacy towards structurally different nerve agents and stereoselectivity towards the toxic P(-) VX enantiomer in vitro and offer promise for use as bioscavengers in vivo.
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Affiliation(s)
- Anja Köhler
- Institut für Pharmakologie und Toxikologie der Bundeswehr, 80937, Munich, Germany
- Lehrstuhl für Biologische Chemie, Technische Universität München, 85354, Freising, Germany
| | - Benjamin Escher
- Lehrstuhl für Biologische Chemie, Technische Universität München, 85354, Freising, Germany
| | - Laura Job
- Lehrstuhl für Biologische Chemie, Technische Universität München, 85354, Freising, Germany
| | - Marianne Koller
- Institut für Pharmakologie und Toxikologie der Bundeswehr, 80937, Munich, Germany
| | - Horst Thiermann
- Institut für Pharmakologie und Toxikologie der Bundeswehr, 80937, Munich, Germany
| | - Arne Skerra
- Lehrstuhl für Biologische Chemie, Technische Universität München, 85354, Freising, Germany.
| | - Franz Worek
- Institut für Pharmakologie und Toxikologie der Bundeswehr, 80937, Munich, Germany.
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Köhler A, Job L, Worek F, Skerra A. Inhibition of an organophosphate-detoxifying bacterial phosphotriesterase by albumin and plasma thiol components. Toxicol Lett 2021; 350:194-201. [PMID: 34303790 DOI: 10.1016/j.toxlet.2021.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/13/2021] [Accepted: 07/19/2021] [Indexed: 11/28/2022]
Abstract
The phosphotriesterase of the bacterium Brevundimonas diminuta (BdPTE) is a naturally occurring enzyme that catalyzes the hydrolysis of organophosphate (OP) nerve agents as well as pesticides and offers a potential treatment of corresponding intoxications. While BdPTE mutants with improved catalytic efficiencies against several OPs have been described, unexpectedly, less efficient breakdown of an OP was observed upon application in an animal model compared with in vitro measurements. Here, we describe detailed inhibition studies with the high-activity BdPTE mutant 10-2C3(C59M/C227A) by human plasma components, indicating that this enzyme is inhibited by serum albumin. The inhibitory activity is mediated by depletion of crucial zinc ions from the BdPTE active site, either via the known high-affinity zinc binding site of albumin or via chemical complex formation with its free thiol side chain at position Cys34. Albumin pre-charged with zinc ions or carrying a chemically blocked Cys34 side chain showed significantly reduced inhibitory activity; in fact, the combination of both measures completely abolished BdPTE inhibition. Consequently, the available zinc ion concentration in blood plays an important role for BdPTE activity in vivo and should be taken into account for therapeutic development and application of a catalytic OP scavenger.
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Affiliation(s)
- Anja Köhler
- Chair of Biological Chemistry, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany; Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstr. 11, 80937 Munich, Germany.
| | - Laura Job
- Chair of Biological Chemistry, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstr. 11, 80937 Munich, Germany.
| | - Arne Skerra
- Chair of Biological Chemistry, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany.
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John H, Thiermann H. Poisoning by organophosphorus nerve agents and pesticides: An overview of the principle strategies and current progress of mass spectrometry-based procedures for verification. J Mass Spectrom Adv Clin Lab 2021; 19:20-31. [PMID: 34820662 PMCID: PMC8601002 DOI: 10.1016/j.jmsacl.2021.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/02/2020] [Accepted: 01/03/2021] [Indexed: 02/07/2023] Open
Abstract
Evidence of poisoning with organophosphorus (OP) nerve agents requires biomedical verification. OP nerve agents undergo common biotransformation pathways producing valuable biomarkers. Internationally accepted methods target remaining poison, hydrolysis products and protein-adducts. Mass spectrometry-based methods provide optimum selectivity and sensitivity for identification. Methods, strategies, current proceedings, quality criteria and real cases of poisoning are presented.
Intoxication by organophosphorus (OP) poisons, like nerve agents and pesticides, is characterized by the life-threatening inhibition of acetylcholinesterase (AChE) caused by covalent reaction with the serine residue of the active site of the enzyme (phosphylation). Similar reactions occur with butyrylcholinesterase (BChE) and serum albumin present in blood as dissolved proteins. For forensic purposes, products (adducts) with the latter proteins are highly valuable long-lived biomarkers of exposure to OP agents that are accessible by diverse mass spectrometric procedures. In addition, the evidence of poison incorporation might also succeed by the detection of remaining traces of the agent itself, but more likely its hydrolysis and/or enzymatic degradation products. These relatively short-lived molecules are distributed in blood and tissue, and excreted via urine. This review presents the mass spectrometry-based methods targeting the different groups of biomarkers in biological samples, which are already internationally accepted by the Organisation for the Prohibition of Chemical Weapons (OPCW), introduces novel approaches in the field of biomedical verification, and outlines the strict quality criteria that must be fulfilled for unambiguous forensic analysis.
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Koller M, Thiermann H, Worek F. Screening of chiral shift reagents suitable to generically separate the enantiomers of V-agents by 31P-NMR spectroscopy. Toxicol Lett 2020; 320:28-36. [PMID: 31805340 DOI: 10.1016/j.toxlet.2019.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/28/2019] [Accepted: 12/01/2019] [Indexed: 11/30/2022]
Abstract
Fourteen amino acids protected at the N-terminal and at their side chains were screened for resolving the enantiomers of V-agents by NMR. While none of the shift reagents tested showed really effective separation in proton NMR, two of them (BOC-Gln(Xan)-OH, 16, and Z-Arg(Z)2-OH), 21, with 16 superior to 21) were found suitable to separate the enantiomers of all V-agent homologues involved in the test by 31P-NMR. Molar ratios investigated were 1:0.5, 1:1, 1:1.5, 1:2, and 1:3 with the V-agent set to 1 throughout the experiments. All these ratios were more or less effective, but 1:3 was found to separate the V-agents the most reliable way. It is postulated that three chiral solvating molecules are then coordinated around the organophosphate: ion pair formation with the amino nitrogen of the V agent side chain, hydrogen bonding provided by the PO unit, and extension of coordination at the phosphorus atom itself. After chiral separation of VX by semi-preparative LC-MS the enantiomers were examined with both configurations of 16 releasing four different 31P NMR peaks which correspond to four different complexes: R-S3, R-R3, S-R3, and S-S3. Comparing these results with literature data it is assumed that (+)-VX corresponds to the RP configuration and (-)-VX to the SP-configuration.
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Affiliation(s)
- Marianne Koller
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937, Munich, Germany.
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Abstract
The role of phosphotriesterase as an enzyme which is able to hydrolyze organophosphate compounds cannot be disputed. Contamination by organophosphate (OP) compounds in the environment is alarming, and even more worrying is the toxicity of this compound, which affects the nervous system. Thus, it is important to find a safer way to detoxify, detect and recuperate from the toxicity effects of this compound. Phosphotriesterases (PTEs) are mostly isolated from soil bacteria and are classified as metalloenzymes or metal-dependent enzymes that contain bimetals at the active site. There are three separate pockets to accommodate the substrate into the active site of each PTE. This enzyme generally shows a high catalytic activity towards phosphotriesters. These microbial enzymes are robust and easy to manipulate. Currently, PTEs are widely studied for the detection, detoxification, and enzyme therapies for OP compound poisoning incidents. The discovery and understanding of PTEs would pave ways for greener approaches in biotechnological applications and to solve environmental issues relating to OP contamination.
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Rosenberg Y, Fink J, MacLoughlin R, Ooms-Konecny T, Sullivan D, Gerk W, Mao L, Jiang X, Lees J, Urban L, Rajendran N. Aerosolized recombinant human butyrylcholinesterase delivered by a nebulizer provides long term protection against inhaled paraoxon in macaques. Chem Biol Interact 2019; 309:108712. [PMID: 31201777 DOI: 10.1016/j.cbi.2019.06.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/05/2019] [Accepted: 06/11/2019] [Indexed: 02/07/2023]
Abstract
The recent intentional use of nerve agents and pesticides in Europe and Afghanistan highlights the need for an effective countermeasure against organophosphates (OP) toxins. The most developed pretreatment candidate to date is plasma (native) human butyrylcholinesterase (HuBChE), which is limited in availability and because of its 1:1 stoichiometry with OPs, a large dose will present challenges when delivered parenterally both in terms of pharmacokinetics and manageability in the field. A tetrameric recombinant (r) form of human BChE produced in CHO-K1 cells with similar structure, in vivo stability and antidotal efficacy as the native form, has been developed to deliver rHuBChE as an aerosol (aer) to form a pulmonary bioshield capable of neutralizing inhaled OPs in situ and prevent AChE inhibition in the blood and in the brain; the latter associated with the symptoms of OP toxicity. Previous proof-of-concept macaque studies demonstrated that delivery of 9 mg/kg using a microsprayer inserted down the trachea, resulted in protection against an inhaled dose of 15ug/kg of aer-paraoxon (aer-Px) given 72 h later. In the present studies, pulmonary delivery of rHuBChE in macaques was achieved using Aerogen vibrating mesh nebulizers, similar to that used for human self-administration. The promising findings indicate that despite the poor lung deposition observed in macaques using nebulizers (13-20%), protective levels of RBC-AChE were still present in the blood even when exposure aer-Px (55 μg/kg) was delayed for five days. This long term retention of 5 mg/kg rHuBChE deposited in the lung bodes well for the use of an aer-rHuBChE pretreatment in humans where a user-friendly customized nebulizer with increased lung deposition up to 50% will provide even longer protection at a lower dose.
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Affiliation(s)
| | - James Fink
- Department of Respiratory Care, Texas State University, Round Rock, TX, 78665, USA
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Herbert J, Thiermann H, Worek F, Wille T. COPD and asthma therapeutics for supportive treatment in organophosphate poisoning. Clin Toxicol (Phila) 2019; 57:644-651. [PMID: 30696282 DOI: 10.1080/15563650.2018.1540785] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Context: Nerve agents like sarin or VX have repeatedly been used in military conflicts or homicidal attacks, as seen in Syria or Malaysia 2017. Together with pesticides, nerve agents assort as organophosphorus compounds (OP), which inhibit the enzyme acetylcholinesterase. To counteract subsequent fatal symptoms due to acetylcholine (ACh) accumulation, oximes plus atropine are administered, a regimen that lacks efficacy in several cases of OP poisoning. New therapeutics are in development, but still need evaluation before clinical employment. Supportive treatment with already approved drugs presents an alternative, whereby compounds from COPD and asthma therapy are likely options. A recent pilot study by Chowdhury et al. included β2-agonist salbutamol in the treatment of OP-pesticide poisoned patients, yielding ambiguous results concerning the addition. Here, we provide experimental data for further investigations regarding the value of these drugs in OP poisoning. Methods: By video-microscopy, changes in airway area were analyzed in VX-poisoned rat precision cut lung slices (PCLS) after ACh-induced airway contraction and subsequent application of selected anticholinergics/β2-agonists. Results: Glycopyrrolate and ipratropium efficiently antagonized an ACh-induced airway contraction in VX-poisoned PCLS (EC50 glycopyrrolate 15.8 nmol/L, EC50 ipratropium 2.3 nmol/L). β2-agonists formoterol and salbutamol had only negligible effects when solely applied in the same setting. However, combination of formoterol or salbutamol with low dosed glycopyrrolate or atropine led to an additive effect compared to the sole application [50.6 ± 8.8% airway area increase after 10 nmol/L formoterol +1 nmol/L atropine versus 11.7 ± 9.2% (10 nmol/L formoterol) or 8.6 ± 5.9% (1 nmol/L atropine)]. Discussion: We showed antagonizing effects of anticholinergics and β2-agonists on ACh-induced airway contractions in VX-poisoned PCLS, thus providing experimental data to support a prospective comprehensive clinical study. Conclusions: Our results indicate that COPD and asthma therapeutics could be a valuable addition to the treatment of OP poisoning.
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Affiliation(s)
- Julia Herbert
- a Bundeswehr Institute of Pharmacology and Toxicology , Neuherbergstraße 11, Munich , Germany
| | - Horst Thiermann
- a Bundeswehr Institute of Pharmacology and Toxicology , Neuherbergstraße 11, Munich , Germany
| | - Franz Worek
- a Bundeswehr Institute of Pharmacology and Toxicology , Neuherbergstraße 11, Munich , Germany
| | - Timo Wille
- a Bundeswehr Institute of Pharmacology and Toxicology , Neuherbergstraße 11, Munich , Germany
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Lushchekina S, Masson P. Catalytic bioscavengers against organophosphorus agents: mechanistic issues of self-reactivating cholinesterases. Toxicology 2018; 409:91-102. [DOI: 10.1016/j.tox.2018.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 12/21/2022]
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Marquart K, Herbert J, Amend N, Thiermann H, Worek F, Wille T. Effect of cholinergic crisis on the potency of different emergency anaesthesia protocols in soman-poisoned rats. Clin Toxicol (Phila) 2018; 57:343-349. [PMID: 30307341 DOI: 10.1080/15563650.2018.1520241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND In a military or terrorist scenario, combination of organophosphorus compounds (OP) poisoning with physical trauma requiring surgical treatment and thus general anaesthesia are possible. Previous in vitro studies showed an altered potency of relevant anaesthetics during cholinergic crisis. Hence, it is not clear, which anaesthetics are suitable to achieve the necessary stage of surgical anaesthesia in OP poisoning. METHODS In the present study, different anaesthetic regimens (ketamine-midazolam, propofol-fentanyl, thiopental-fentanyl), relevant in military emergency medicine, were examined in soman-poisoned rats. Clinical signs and cardiovascular variables were recorded continuously. Blood samples for acetylcholinesterase (AChE) activity were drawn. After euthanasia or death of the animals, brain and diaphragm were collected for cholinesterase assays. RESULTS Propofol-fentanyl and thiopental-fentanyl resulted in surgical anaesthesia throughout the experiments. With ketamine-midazolam, surgical anaesthesia without respiratory impairment could not be achieved in pilot experiments (no soman challenge) and was therefore not included in the study. Soman-poisoned and control animals required a comparable amount of propofol-fentanyl or thiopental-fentanyl. In combination with atropine, significantly less propofol was needed. Survival rate was higher with thiopental compared to propofol. Atropine improved survival in both groups. Blood and tissue AChE activities were strongly inhibited after soman administration with and without atropine treatment. DISCUSSION The current in vivo study did not confirm concerns of altered potency of existing anaesthetic protocols for the application of propofol or thiopental with fentanyl due to soman poisoning. Despite severe cholinergic crisis, sufficient anaesthetic depth could be achieved in all animals. CONCLUSION Further experiments in in vivo models closer to human pharmaco- and toxicokinetics (e.g., swine) are required for confirmation of the initial findings and for improving extrapolation to humans.
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Affiliation(s)
- Katharina Marquart
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Julia Herbert
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Niko Amend
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Horst Thiermann
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Franz Worek
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
| | - Timo Wille
- a Bundeswehr Institute of Pharmacology and Toxicology , Munich , Germany
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Napon G, Dafferner AJ, Saxena A, Lockridge O. Identification of Carboxylesterase, Butyrylcholinesterase, Acetylcholinesterase, Paraoxonase, and Albumin Pseudoesterase in Guinea Pig Plasma through Nondenaturing Gel Electrophoresis. Comp Med 2018; 68:367-374. [PMID: 30278860 DOI: 10.30802/aalas-cm-18-000047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Drugs to protect against nerve agent toxicity are tested in animals. The current preferred small animal model is guinea pigs because their plasma bioscavenging capacity resembles that of NHP. We stained nondenaturing polyacrylamide slab gels with a variety of substrates, inhibitors, and antibodies to identify the esterases in heparinized guinea pig plasma. An intense band of carboxylesterase activity migrated behind albumin. Minor carboxylesterase bands were revealed after background activity from paraoxonase was inhibited by using EDTA. The major butyrylcholinesterase band was a disulfide-linked dimer. Incubation with the antihuman butyrylcholinesterase antibody B2 18-5 shifted the butyrylcholinesterase dimer band to slower migrating complexes. Carboxylesterases were distinguished from butyrylcholinesterase by their sensitivity to inhibition by bis-p-nitrophenyl phosphate. Acetylcholinesterase tetramers formed a complex with the antihuman acetylcholinesterase antibody HR2. Organophosphorus toxicants including cresyl saligenin phosphate, dichlorvos, and chlorpyrifos oxon irreversibly inhibited the serine esterases but not paraoxonase. Albumin pseudoesterase activity was seen in gels stained with α- or β-naphthyl acetate and fast blue RR. We conclude that guinea pig plasma has 2 types of carboxylesterase, butyrylcholinesterase dimers and 5 minor butyrylcholinesterase forms, a small amount of acetylcholinesterase tetramers, paraoxonase, and albumin pseudoesterase activity. A knockout mouse with no carboxylesterase activity in plasma is available and may prove to be a better model for studies of nerve agent toxicology than guinea pigs.
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Affiliation(s)
- Geoffroy Napon
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA; University of Nebraska-Omaha, Omaha, Nebraska, USA
| | - Alicia J Dafferner
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Ashima Saxena
- Division of Biochemistry, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA; US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Oksana Lockridge
- Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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16
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Automated Design of Efficient and Functionally Diverse Enzyme Repertoires. Mol Cell 2018; 72:178-186.e5. [PMID: 30270109 DOI: 10.1016/j.molcel.2018.08.033] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/02/2018] [Accepted: 08/21/2018] [Indexed: 11/22/2022]
Abstract
Substantial improvements in enzyme activity demand multiple mutations at spatially proximal positions in the active site. Such mutations, however, often exhibit unpredictable epistatic (non-additive) effects on activity. Here we describe FuncLib, an automated method for designing multipoint mutations at enzyme active sites using phylogenetic analysis and Rosetta design calculations. We applied FuncLib to two unrelated enzymes, a phosphotriesterase and an acetyl-CoA synthetase. All designs were active, and most showed activity profiles that significantly differed from the wild-type and from one another. Several dozen designs with only 3-6 active-site mutations exhibited 10- to 4,000-fold higher efficiencies with a range of alternative substrates, including hydrolysis of the toxic organophosphate nerve agents soman and cyclosarin and synthesis of butyryl-CoA. FuncLib is implemented as a web server (http://FuncLib.weizmann.ac.il); it circumvents iterative, high-throughput experimental screens and opens the way to designing highly efficient and diverse catalytic repertoires.
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17
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Catalytic bioscavengers as countermeasures against organophosphate nerve agents. Chem Biol Interact 2018; 292:50-64. [DOI: 10.1016/j.cbi.2018.07.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 12/30/2022]
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18
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19
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Lushchekina SV, Schopfer LM, Grigorenko BL, Nemukhin AV, Varfolomeev SD, Lockridge O, Masson P. Optimization of Cholinesterase-Based Catalytic Bioscavengers Against Organophosphorus Agents. Front Pharmacol 2018; 9:211. [PMID: 29593539 PMCID: PMC5859046 DOI: 10.3389/fphar.2018.00211] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 02/26/2018] [Indexed: 11/13/2022] Open
Abstract
Organophosphorus agents (OPs) are irreversible inhibitors of acetylcholinesterase (AChE). OP poisoning causes major cholinergic syndrome. Current medical counter-measures mitigate the acute effects but have limited action against OP-induced brain damage. Bioscavengers are appealing alternative therapeutic approach because they neutralize OPs in bloodstream before they reach physiological targets. First generation bioscavengers are stoichiometric bioscavengers. However, stoichiometric neutralization requires administration of huge doses of enzyme. Second generation bioscavengers are catalytic bioscavengers capable of detoxifying OPs with a turnover. High bimolecular rate constants (kcat/Km > 106 M−1min−1) are required, so that low enzyme doses can be administered. Cholinesterases (ChE) are attractive candidates because OPs are hemi-substrates. Moderate OP hydrolase (OPase) activity has been observed for certain natural ChEs and for G117H-based human BChE mutants made by site-directed mutagenesis. However, before mutated ChEs can become operational catalytic bioscavengers their dephosphylation rate constant must be increased by several orders of magnitude. New strategies for converting ChEs into fast OPase are based either on combinational approaches or on computer redesign of enzyme. The keystone for rational conversion of ChEs into OPases is to understand the reaction mechanisms with OPs. In the present work we propose that efficient OP hydrolysis can be achieved by re-designing the configuration of enzyme active center residues and by creating specific routes for attack of water molecules and proton transfer. Four directions for nucleophilic attack of water on phosphorus atom were defined. Changes must lead to a novel enzyme, wherein OP hydrolysis wins over competing aging reactions. Kinetic, crystallographic, and computational data have been accumulated that describe mechanisms of reactions involving ChEs. From these studies, it appears that introducing new groups that create a stable H-bonded network susceptible to activate and orient water molecule, stabilize transition states (TS), and intermediates may determine whether dephosphylation is favored over aging. Mutations on key residues (L286, F329, F398) were considered. QM/MM calculations suggest that mutation L286H combined to other mutations favors water attack from apical position. However, the aging reaction is competing. Axial direction of water attack is not favorable to aging. QM/MM calculation shows that F329H+F398H-based multiple mutants display favorable energy barrier for fast reactivation without aging.
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Affiliation(s)
- Sofya V Lushchekina
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia
| | - Lawrence M Schopfer
- Department of Biochemistry and Molecular Biology, Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Bella L Grigorenko
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Alexander V Nemukhin
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Sergei D Varfolomeev
- Laboratory of Computer Modeling of Bimolecular Systems and Nanomaterials, N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia.,Chemistry Department, Lomonosov State University, Moscow, Russia
| | - Oksana Lockridge
- Department of Biochemistry and Molecular Biology, Eppley Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Patrick Masson
- Neuropharmacology Laboratory, Kazan Federal University, Kazan, Russia
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Herbert J, Thiermann H, Worek F, Wille T. Precision cut lung slices as test system for candidate therapeutics in organophosphate poisoning. Toxicology 2017; 389:94-100. [DOI: 10.1016/j.tox.2017.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/14/2017] [Accepted: 07/18/2017] [Indexed: 01/23/2023]
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21
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Masson P, Nachon F. Cholinesterase reactivators and bioscavengers for pre- and post-exposure treatments of organophosphorus poisoning. J Neurochem 2017; 142 Suppl 2:26-40. [PMID: 28542985 DOI: 10.1111/jnc.14026] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/02/2017] [Accepted: 03/10/2017] [Indexed: 12/11/2022]
Abstract
Organophosphorus agents (OPs) irreversibly inhibit acetylcholinesterase (AChE) causing a major cholinergic syndrome. The medical counter-measures of OP poisoning have not evolved for the last 30 years with carbamates for pretreatment, pyridinium oximes-based AChE reactivators, antimuscarinic drugs and neuroprotective benzodiazepines for post-exposure treatment. These drugs ensure protection of peripheral nervous system and mitigate acute effects of OP lethal doses. However, they have significant limitations. Pyridostigmine and oximes do not protect/reactivate central AChE. Oximes poorly reactivate AChE inhibited by phosphoramidates. In addition, current neuroprotectants do not protect the central nervous system shortly after the onset of seizures when brain damage becomes irreversible. New therapeutic approaches for pre- and post-exposure treatments involve detoxification of OP molecules before they reach their molecular targets by administrating catalytic bioscavengers, among them phosphotriesterases are the most promising. Novel generation of broad spectrum reactivators are designed for crossing the blood-brain barrier and reactivate central AChE. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Patrick Masson
- Neuropharmacology Laboratory, Kazan Federal University, Kazan, Russia
| | - Florian Nachon
- Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, Cédex, France
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22
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Goldsmith M, Aggarwal N, Ashani Y, Jubran H, Greisen PJ, Ovchinnikov S, Leader H, Baker D, Sussman JL, Goldenzweig A, Fleishman SJ, Tawfik DS. Overcoming an optimization plateau in the directed evolution of highly efficient nerve agent bioscavengers. Protein Eng Des Sel 2017; 30:333-345. [DOI: 10.1093/protein/gzx003] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/10/2017] [Indexed: 11/13/2022] Open
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