The Structure and Mechanism of Cytochrome P450

Sa？etak The unusual hemoprotein called cytochrome P450 is now recognized as representing a variety of monooxygenases with entirely different substrate specificities. In comparison with hememercaptide models it can be concluded that the unusual spectral properties reside in a heme-mercaptide linkage to the protein. The sixth ligand in the ferric form could be a hydroxyl group which is absent in the enzyme-substrate complex. In the reaction cycle the enzyme-substrate complex is reduced and then reacts with dioxygen to form an oxy-complex. Further reduction is believed to yield an ？oxenoid？ complex of the structure [Fe0]3+, which transfers the oxygen atom to the substrate