title: The involvement of cytochrome P-488 and P-450 in NADH-dependent O-demethylation of p-nitroanisole in rat liver microsomes.
abstract: These studies have shown that addition of p-nitroanisole to a reaction mixture containing rat liver microsomes resulted in an increase the reoxidation rate of NADH-reduced cytochrome b5. Fortification of rat liver microsomes with partially purified cytochrome b5 produces an increase in both NADPH-dependent and NADH-dependent p-nitroanisole O-demethylation activity. Antiserum to cytochrome P-450 isolated from phenobarbital-treated rat liver microsomes inhibited the NADH-dependent O-demethylation activity as well as the NADPH-dependent O-demethylation activity seen in rat liver microsomes. Addition of either purified cytochrome P-450 or cytochrome P-448 to an incubation mixture containing phenobarbital-treated rat liver microsomes enhanced the NADH-dependent p-nitroanisole O-demethylation activity. These results suggest that NADH-dependent and, in part, NADPH-dependent O-demethylations are catalyzed by cytochrome P-448 and cytochrome P-450 receiving electrons from cytochrome b5.
mesh_terms: D000818:Animals; D000906:Antibodies; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000201:enzymology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009575:Nitroanisole O-Demethylase / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
chemical_list: D000906:Antibodies; D003580:Cytochromes; D009243:NAD; D009249:NADP; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D009575:Nitroanisole O-Demethylase; D010088:Oxidoreductases