HYDROGEN PEROXIDE-SUPPORTED ACTIVITIES OF SEMISYNTHETIC FLAVOCYTOCHROME 2B4

Semisynthetic flavocytochromes, obtained by covalent binding of ribofl avin with cytochromes P450 2B4, were able to catalyze the H2O2-mediate d reactions of aniline p-hydroxylation, aminopyrine N-demethylation an d p-nitroanizole O-dealkylation. The rates of the flavocytochrome-cata lyzed, H2O2-supported reactions far exceeded those of the appropriate NADH-dependent reactions and were comparable with the cytochrome P450 2B4-catalyzed, peroxide-mediated reaction rates. The kinetic parameter s (k(cat), K-m) for the peroxide-dependent flavocytochrome P450 2B4 re actions were obtained. Sodium cyanide and SKF-525A, a specific P450 in hibitor, were both shown to inhibit these reactions. The generation of active oxygen species by flavocytochrome 2B4 was registered by chemil uminescence intensity.