Hepatic microsomal alcohol-oxidizing system. Affinity for methanol, ethanol, propanol, and butanol.
Oxidation of methanol, ethanol, propanol, and butanol by the microsomal fraction of rat liver homogenate is described. This microsomal alcohol-oxidizing system is dependent on NADPH and molecular oxygen and is partially inhibited by CO, features which are common for microsomal drug-metabolizing enzymes. The activity of the microsomal alcohol-oxidizing system could be dissociated from the alcohol peroxidation via catalase-H2O2 by differences in substrate specificity, since higher aliphatic alcohols react only with the microsomal system, but not with catalase-H2O2. Following solubilization of microsomes by ultrasonication and treatment with deoxycholate, the activity of the microsomal alcohol-oxidizing system was separated from contaminating catalase by DEAE-cellulose column chromatography, ruling out an obligatory involvement of catalase-H2O2 in the activity of the NADPH-dependent microsomal alcohol-oxidizing system. In intact hepatic microsomes, the catalase inhibitor sodium azide slightly decreased the oxidation of methanol and ethanol, but not that of propanol and butanol, indicating a facultative role of contaminating catalase in the microsomal oxidation of lower aliphatic alcohols only. It is suggested that the microsomal alcohol-oxidizing system accounts, at least in part, for that fraction of hepatic alcohol metabolism which is independent of the pathway involving alcohol dehydrogenase activity.
D000433:1-Propanol; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000818:Animals; D001386:Azides / Q000494:pharmacology; D000440:Butanols; D000431:Ethanol; D007700:Kinetics; D008297:Male; D000432:Methanol; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009249:NADP; D010084:Oxidation-Reduction; D051381:Rats; D013329:Structure-Activity Relationship
D001386:Azides; D000440:Butanols; D000431:Ethanol; D009249:NADP; D000433:1-Propanol; D000429:Alcohol Oxidoreductases; D000432:Methanol