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Reactivation of VX-Inhibited Human Acetylcholinesterase by Deprotonated Pralidoxime. A Complementary Quantum
Jorge Alberto Valle da Silva1, Ander Francisco Pereira2, Steven R LaPlante3
1Chemical, Biological, Radiological and Nuclear Defense Institute, Avenida das Americas, 28705, Guaratiba, 23020-470 Rio de Janeiro/RJ, Brazil.
Abstract:
In the present work, we performed a complementary quantum mechanical (QM) study to describe the mechanism by which deprotonated pralidoxime (2-PAM) could reactivate human (Homo sapiens sapiens) acetylcholinesterase (HssAChE) inhibited by the nerve agent VX. Such a reaction is proposed to occur in subsequent addition-elimination steps, starting with a nucleophile bimolecular substitution (SN2) mechanism through the formation of a trigonal bipyramidal transition state (TS). A near attack conformation (NAC), obtained in a former study using molecular mechanics (MM) calculations, was taken as a starting point for this project, where we described the possible formation of the TS. Together, this combined QM/MM study on AChE reactivation shows the feasibility of the reactivation occurring via attack of the deprotonated form of 2-PAM against the Ser203-VX adduct of HssAChE.
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