Structure and chemistry of cytochrome P450

Cytochrome P450s, abbreviated CYP, are now recognized to occupy a great variety of phylogenetically distributed isoform activities, and these are variations in metabolic profile and substrate specificity are ultimately dictated by the bioinorganic chemistry of heme iron and oxygen as controlled by the protein environment. This review attempts to place the current knowledge base of cytochrome P450 structure-function in context with the general aspects of metalloenzyme function. Topics discussed are as follows: (a) active-site structure of P450 enzymes; (b) enzymatic reaction cycle of cytochrome P450; (c) role of distal pocket in P450 dioxygen activation; (d) crystallographic characterization of P450 reaction intermediates; and (e) alternative proton-transfer pathways in functionally different cytochrome P450s.