title: The mechanistic plurality of cytochrome P-450 and its biological ramifications.
abstract: The mechanistic plurality of the microsomal cytochrome P-450 enzyme system is illustrated by studies of the oxidative metabolism of benzo[a]pyrene, 3-hydroxybenzo[a]pyrene and arachidonic acid. Rat liver microsomal metabolism of benzo[a]pyrene or 3-hydroxy-benzo[a]pyrene, supported by cumene hydroperoxide, generates benzo[a]pyrene quinones via molecular oxygen-dependent and -independent pathways. Arachidonic acid is metabolized by rat liver microsomal fractions to a variety of oxygenated products, including cis-trans diene conjugated monohydroxy-acids, epoxy-acids as well as omega- and omega-1-oxidation products. The chemistry of the different reaction products is discussed in terms of the possible mechanisms responsible for their formation and the role of the haemoprotein during catalysis. An integrated view for the reaction cycle of cytochrome P-450 is presented.
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D001555:Benzene Derivatives / Q000378:metabolism; D001564:Benzo(a)pyrene; D001580:Benzopyrenes / Q000378:metabolism; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000201:enzymology; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats
chemical_list: D001095:Arachidonic Acids; D001555:Benzene Derivatives; D001580:Benzopyrenes; D004852:Epoxy Compounds; D016718:Arachidonic Acid; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D009251:NADPH-Ferrihemoprotein Reductase; C007164:cumene hydroperoxide; D010634:Phenobarbital