P450 enzymes are ubiquitous heme-containing monooxygenases and involved in a number of vital processes including carcinogenesis and drug metabolism as well as the biosynthesis of steroid hormones and fat-soluble vitamin metabolism and the conversion of polyunsaturated fatty acids to biologically active molecules. Recent advances in understanding structure-function relationships in cytochrome P450 are summarized. Of particular importance is the role that plays in P450 function, where the active site undergoes large open/close motions to enable substrates to bind and products to leave and electron transfer pathways.

Key words: cytochrome P450, hydroxylation, structure, catalytic mechanism, function