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Two possible orientations of the HI-6 molecule in the reactivation of organophosphate-inhibited acetylcholinesterase. 2003

Chunyuan Luo, and Haim Leader, and Zoran Radic, and Donald M Maxwell, and Palmer Taylor, and Bhupendra P Doctor, and Ashima Saxena
Division of Biochemistry, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA. chunyuan.luo@na.amedd.army.mil

The inhibition of acetylcholinesterase (AChE) by organophosphorus compounds (OPs) causes acute toxicity or death of the intoxicated individual. One group of these compounds, the OP nerve agents, pose an increasing threat in the world due to their possible use in the battlefield or terrorist acts. Antidotes containing oxime compounds to reactivate the inhibited enzyme are highly valued for treatment against OP poisoning. One of these reactivators, HI-6, was shown to be significantly more effective in treating soman toxicity than other oximes, such as 2-PAM, TMB4, and obidoxime. However, HI-6 was less effective in reactivating AChE inhibited by the OP pesticide, paraoxon. In this study, the mechanism for HI-6-induced reactivation of OP-AChE conjugates was investigated using mouse mutant AChEs inhibited with different OPs including organophosphate paraoxon, and several methylphosphonates. Results indicate that the HI-6 molecule may assume two different orientations in the reactivation of AChE inhibited by organophosphate and Sp methylphosphonates. These conclusions were further corroborated by reactivation studies using an analog of HI-6 in which the bispyridinium moieties are linked by a methylene bridge rather than an ether oxygen.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D009943 Organophosphorus Compounds Organic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is broad array of synthetic compounds that are used as PESTICIDES and DRUGS. Organophosphorus Compound,Organopyrophosphorus Compound,Organopyrophosphorus Compounds,Compound, Organophosphorus,Compound, Organopyrophosphorus,Compounds, Organophosphorus,Compounds, Organopyrophosphorus
D010091 Oximes Compounds that contain the radical R2C Aldoximes,Hydroxyimino Compounds,Ketoxime,Ketoximes,Oxime,Compounds, Hydroxyimino
D010261 Paraoxon An organophosphate cholinesterase inhibitor that is used as a pesticide. Diethyl-p-Nitrophenyl Phosphate,E-600,Fosfakol,Phosphacol,Diethyl p Nitrophenyl Phosphate,E 600,E600,Phosphate, Diethyl-p-Nitrophenyl
D011726 Pyridinium Compounds Derivatives of PYRIDINE containing a cation C5H5NH or radical C5H6N. Compounds, Pyridinium
D002800 Cholinesterase Inhibitors Drugs that inhibit cholinesterases. The neurotransmitter ACETYLCHOLINE is rapidly hydrolyzed, and thereby inactivated, by cholinesterases. When cholinesterases are inhibited, the action of endogenously released acetylcholine at cholinergic synapses is potentiated. Cholinesterase inhibitors are widely used clinically for their potentiation of cholinergic inputs to the gastrointestinal tract and urinary bladder, the eye, and skeletal muscles; they are also used for their effects on the heart and the central nervous system. Acetylcholinesterase Inhibitor,Acetylcholinesterase Inhibitors,Anti-Cholinesterase,Anticholinesterase,Anticholinesterase Agent,Anticholinesterase Agents,Anticholinesterase Drug,Cholinesterase Inhibitor,Anti-Cholinesterases,Anticholinesterase Drugs,Anticholinesterases,Cholinesterase Inhibitors, Irreversible,Cholinesterase Inhibitors, Reversible,Agent, Anticholinesterase,Agents, Anticholinesterase,Anti Cholinesterase,Anti Cholinesterases,Drug, Anticholinesterase,Drugs, Anticholinesterase,Inhibitor, Acetylcholinesterase,Inhibitor, Cholinesterase,Inhibitors, Acetylcholinesterase,Inhibitors, Cholinesterase,Inhibitors, Irreversible Cholinesterase,Inhibitors, Reversible Cholinesterase,Irreversible Cholinesterase Inhibitors,Reversible Cholinesterase Inhibitors
D002801 Cholinesterase Reactivators Drugs used to reverse the inactivation of cholinesterase caused by organophosphates or sulfonates. They are an important component of therapy in agricultural, industrial, and military poisonings by organophosphates and sulfonates. Insecticides, Organophosphate, Antagonists,Insecticides, Organothiophosphate, Antagonists,Organophosphate Insecticide Antagonists,Organothiophosphate Insecticide Antagonists,Antagonists, Organophosphate Insecticide,Antagonists, Organothiophosphate Insecticide,Insecticide Antagonists, Organophosphate,Insecticide Antagonists, Organothiophosphate,Reactivators, Cholinesterase
D004347 Drug Interactions The action of a drug that may affect the activity, metabolism, or toxicity of another drug. Drug Interaction,Interaction, Drug,Interactions, Drug
D000110 Acetylcholinesterase An enzyme that catalyzes the hydrolysis of ACETYLCHOLINE to CHOLINE and acetate. In the CNS, this enzyme plays a role in the function of peripheral neuromuscular junctions. EC 3.1.1.7. Acetylcholine Hydrolase,Acetylthiocholinesterase,Hydrolase, Acetylcholine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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