OXIDATIVE BIODEGRADATION OF PHOSPHOROTHIOLATES BY FUNGAL LACCASE

Organophosphorus (OP) insecticides and nerve agents that contain P-S b ond are relatively more resistant to enzymatic hydrolysis. Purified ph enol oxidase (laccase) from the white rot fungus Pleurotus ostreatus ( Po) together with the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-s ulfonate) (ABTS) displayed complete and rapid oxidative degradation of the nerve agents VX and Russian VX (RVX) and the insecticide analog d iisopropyl-Amiton with specific activity: k(sp) = 2200, 667 and 1833 n mol min(-1) mg(-1), respectively (pH 7.4, 37 degrees C). A molar ratio of 1:20 for OP/ABTS and 0.05 M phosphate at pH 7.4 provided the highe st degradation rate of VX and RVX, The thermostable laccase purified f rom the fungus Chaetomium thermophilium (Ct) in the presence of ARTS c aused a 52-fold slower degradation of VX with k(sp) = 42 nmol min(-1) mg(-1). The enzymatic biodegradation products were identified by P-31- NMR and GC/MS analysis. (C) 1998 Federation of European Biochemical So cieties.