Reactivity patterns of cytochrome P450 enzymes: Multifunctionality of the active species, and the two states-two oxidants conundrum

This focused review discusses mechanisms of oxygenation of organic compounds by cytochrome P450, based on density functional theory (DFT) and hybrid DFT and molecular mechanics (DFT/MM). The reactivity of the active species, Compound I, generally involves two-state reactivity (TSR) and sometimes multi-state reactivity (MSR). The reactivity of the ferric-hydroperoxide species (Compound 0) is reviewed too. According to DFT calculations, Compound 0 must be silent in the presence of Compound I. Much of the experimental mechanistic data is shown to be accounted for by the TSR/MSR concept.