title: The properties of cytochrome P-450 and hydroxylase activity of reconstituted proteoliposomal membranes.
abstract: Type I substrates are bound to soluble cytochrome P-450 worse than to microsomes. The incorporation of haemoprotein into phosphatidylcholine liposomes restores the capability of isolated cytochrome P-450 to interact with such substrates as well as the microsomal form. The soluble and lipid-binding cytochrome P-450 does not differ in its thermal stability and protease digestion. Liposome-bound cytochrome P-450 has a higher dimethylaniline, aniline and p-nitroanisole hydroxylase activity than its soluble form. Only the aniline hydroxylase activity of microsomal, proteoliposomal and soluble cytochrome P-450 was inhibited by tyrosine . copper (II) complex with NADPH or cumene hydroperoxide as cosubstrates. The inhibitory action of the Tyr2-Cu2+ complex on the other hydroxylase activities depended on the cytochrome P-450 forms and the type of cosubstrates and substrates used.
mesh_terms: D000814:Aniline Compounds; D000818:Animals; D003300:Copper / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D008854:Microscopy, Electron; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D010713:Phosphatidylcholines; D011510:Proteolipids; D011817:Rabbits; D014443:Tyrosine / Q000494:pharmacology
chemical_list: D000814:Aniline Compounds; D008081:Liposomes; D010713:Phosphatidylcholines; D011510:Proteolipids; D014443:Tyrosine; D003300:Copper; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010634:Phenobarbital