Decontamination of nerve agents by immobilized organophosphorus hydrolase

Organophosphorus hydrolase (OPH; EC 3.1.8.1) is known to be capable of hydrolyzing a variety of organophosphorus compounds, such as sarin and paraoxon. We have developed a nerve agent decontamination method using OPH. The gene that encodes OPH was cloned from the bacterial strain Sphingobium fuliginis ATCC 27551, and several OPH gene fusion plasmids were constructed. Escherichia coli was utilized as the expression host for the resulting plasmids. The activities of the recombinant OPH enzymes expressed (KGU0060, KGU0092, and KGU0094) were determined by measuring paraoxon hydrolysis activities. The recombinant OPH enzymes that lacked the signal peptide regions (KGU0092 and KGU0094) were remarkably activated by zinc ion; while the OPH enzyme that contained the signal peptide region (KGU0060) was activated by both zinc and cobalt ions, although the specific activity of this enzyme was much lower than that of KGU0092 or KGU0094. The pH profile demonstrated that the OPH enzymes effectively hydrolyzed the substrate under alkaline conditions. We applied the recombinant OPH to the degradation of nerve agents; it hydrolyzed sarin, tabun, cyclohexyl sarin, and soman with high activities, but not O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX). The enzyme was immobilized to a nickel-chelating sepharose resin. Similarly, all nerve agents could be hydrolyzed by the immobilized enzyme except VX. Our results suggest the possibility for developing a powerful and ecological nerve agent detoxication system using OPH.