Evidence for two different active oxygen species in cytochrome P450 BM3 mediated sulfoxidation and N-dealkylation reactions

Herein, we report the results from two experiments that are consistent with sulfoxidation and N-dealkylation involving two different enzyme substrate complexes and thus two different active oxygen species that do not interchange. The first experiment involves the use of a mutant that may increase the amount of the hydroperoxy-iron species (FeIIIO2H).1 This mutant increases the amount of sulfoxidation relative to the amount of N-dealkylation by 4-fold. In a second experiment, deuterium substitution on the N-methyl groups of substrate does not result in an increase in sulfoxidation. This later result is consistent with N-dealkylation and sulfoxidation being mediated by two different active oxygen species. While the data indicate two active oxygen species, they do not distinguish between the different possibilities for the active oxygen species.