P450

Cytochrome P450 are a family of heme-containing monoxygenases catalyzing the metabolism of xenobiotics in the body where P450 enzymes use O2 and two electrons provided by NAD(P)H with the help of redox partner flavoproteins and iron-sulfur proteins to catalyze the monooxygenation of a variety of substrates. Based on how electrons from NAD(P)H are delivered to the catalytic site, P450 enzymes are divided into four classes, including Class I requiring both an FAD-containing reductase and an iron sulfur redoxin, Class II requiring only an FAD/FMN-containg P450 reductase, Class III requiring no electron donor and Class IV requiring electrons directly from NAD(P)H.