Studies on the mechanism of hepatic microsomal N-oxide formation. N-oxidation of NN-dimethylaniline by a reconstituted rabbit liver microsomal cytochrome P-448 enzyme system.
The N-oxidation of NN-dimethylaniline was studied by using a reconstituted rabbit liver microsomal enzyme system consisting of highly purified cytochrome P-448, NADPH-cytochrome c reductase and lipid factor. Both cytochrome P-448 and NADPH-cytochrome c reductase were required for optimum N-oxygenating activity; the catalytic capacity of the reductase fraction for supporting N-oxide formation varied with the isolation procedure applied. Addition of microsomal lipids to the assay media stimulated N-oxidation of the arylamine. N-Oxide formation appeared to be not generally controlled by electron transfer from cytochrome b5 to cytochrome P-448. The present work confirms that cytochrome P-448 can mediate about 44% of the rabbit liver microsomal N-oxidation of NN-dimethylaniline, thus reinforcing the existence of at least two distinct tertiary amine N-oxidases, i.e. haemoprotein and flavoprotein oxidase, in liver microsomal fractions.
D000814:Aniline Compounds / Q000378:metabolism*; D000818:Animals; D003497:Cyclic N-Oxides / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification; D003580:Cytochromes / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D050356:Lipid Metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D010084:Oxidation-Reduction; D011817:Rabbits
D000814:Aniline Compounds; D003497:Cyclic N-Oxides; D003580:Cytochromes; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase