Studies on the localization of reaction sites within the reduced nicotinamide-adenine dinucleotide phosphate-oxygenase system of rat liver microsomes for the N- and C-oxidation of dimethylaniline and for the peroxidation of unsaturated fatty acids

Abstract

Studies on the localization within the NADPH-oxygenase system of rat liver microsomes of the reaction site for the N-oxidation of dimethylaniline indicate that only the initial component of the electron transport chain, can participate in the reaction. The results support the hypothesis that cytochrome P-450 is essential for the NADPH-dependent peroxidation of unsaturated fatty acids by endoplasmic reticulum, as well as for the C-oxidation of dimethylaniline. Ferrous pyrophosphate, when used as a cofactor to couple NADPH oxidation to the peroxidation of unsaturated fatty acids, produces spectral changes very similar to the absorption spectrum of the cytochrome P-450-carbon monoxide complex. The results further indicate that there are two modes of formaldehyde formation from dimethylaniline: the first, by means of direct oxidation of the C-atom of the methyl group, without participation of dimethylaniline- N-oxide, and the second from dimethylaniline- N-oxide by means of transfer of oxygen from the N- to the C-atom.