Nature's universal oxygenases: the cytochromes P450

Cytochromes P450 are utilized in an enormous diversity of biological reactions, including degradation of xenobiotics, generation of hormones and biosynthesis of a variety of important biological compounds. The cytochrome P450 family is a major participant in nearly all metabolism of pharmaceutical reagents. The presence of different P450 enzymes in various quantities in individuals makes the prediction of drug responses in patients highly complex. A large literature describing mechanistic studies has characterized several intermediates in the oxygenation pathway. It has recently been shown that two or more possible oxygenated forms of the P450 haem can participate in various oxygenations, with some intermediates being highly electrophilic and others being nucleophilic.