The monooxygenase, peroxidase, and peroxygenase properties of cytochrome P450

► The monooxygenase, peroxidase and peroxygenase properties of P450 enzymes have been investigated. ► The conventional O2/NAD(P)H-supported catalytic monooxygenase P450 cycle has been described. ► Surrogate oxidants such as peroxides, peracids, periodate, and iodosobenzene have been outlined. ► Involvement of Compound I as the common transitory monooxygenating P450 species has been described. ► Participation of the ferriperoxo and ferrihydroperoxo monooxygenating species has been proposed.