Molecular Modeling Analysis and Protein Engineering Design for Enhancement of VX Hydrolysis Activity by Organophosphorus Hydrolase from Pseudomonas diminuta

摘要

Bacterial enzymes are used in decontaminating organophosphorus nerve agents and insecticides. This study addresses the use of molecular modeling to find a more positive way for decontaminating the chemical warfare nerve agent o- ethyl S-2-(DIISOPROPYLAMINO)ETHYL methylphosphonothioate (VX). Because organophosphorus hydrolase from Pseudomonas diminuta (OPHPd) has limited hydrolytic activity against VX, a computer-assisted molecular modeling and structure-activity study was done to evaluate OPHPd x-ray crystal structure to identify enzyme regions that could be modified by protein engineering to enhance VX hydrolytic activity. Steric physicochemical, and electrostatic comparisons of the amino acids of the active regions' of the crystal structures of OPHPd and acetylcholinesterase (AChE) from Torpedo californica were made, and the potential hydrolytic mechanisms involved with VX/AChE and VX/OPHPd interactions were analyzed. The results of the ACHE/OPHPd comparisons are discussed, and a protein engineering design to modify specific OPHPd amino acids to enhance VX hydrolysis is reported.