Oxidative biodegradation of phosphorothiolates by fungal laccase

Organophosphorus (OP) insecticides and nerve agents that contain P-S bond are relatively more resistant to enzymatic hydrolysis. Purified phenol oxidase (laccase) from the white rot fungus Pleurotus ostreatus (Po) together with the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) displayed complete and rapid oxidative degradation of the nerve agents VX and Russian VX (RVX) and the insecticide analog diisopropyl-Amiton with specific activity: k(sp)=2200, 667 and 1833 nmol min^-1 mg^-1, respectively (pH 7.4, 37°C). A molar ratio of 1:20 for OP/ABTS and 0.05 M phosphate at pH 7.4 provided the highest degradation rate of VX and RVX. The thermostable laccase purified from the fungus Chaetomium thermophilium (Ct) in the presence of ABTS caused a 52-fold slower degradation of VX with k(sp)=42 nmol min^-1 mg^-1. The enzymatic biodegradation products were identified by ³¹P-NMR and GC/MS analysis. Copyright (C) 1998 Federation of European Biochemical Societies.