Structure and Chemistry of Cytochrome P450

The title to a seminar presentation by I. C. Gunsalus in 1973 was Oxygen: An essential toxin, referring to the complex \nrole that atmospheric dioxygen has in biology. The relatively simple function as terminal oxidant for aerobic life was dramatically \naugmented by Osamu Hayaishi with his identification of an enzyme that catalyzes the conversion of catechol to muconic acid by \noxidative cleavage.1 He named this biological catalyst pyrocatechase, which proved to be the landmark discovery of an enzyme \nthat incorporated atmospheric dioxygen into the carbon chain of the substrate, thereby initiating cleavage of the benzene ring. \nThis review of the oxygenase cytochrome P450 is dedicated to Dr. Hayaishi and…