Ethanol metabolizing system inDrosophila melanogaster: subcellular distribution of some main enzymes

The involvement of catalase in alcohol metabolism in Drosophila melanogaster larvae

The involvement of catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6) in the metabolism of alcohols was investigated by comparing Drosophila melanogaster larvae in which catalase was inhibited by dietary 3-amino-1,2,4-triazole (3AT) to larvae fed a diet without 3AT. 3AT inhibited up to 80% of the catalase activity with concordant small increases in the in vitro activities of sn-glycerol-3-phosphate dehydrogenase, fumarase, and malic enzyme, but with a 16% reduction in the in vivo incorporation of label from [14C]glucose into lipid. When the catalase activity was inhibited to different degrees in ADH-null larvae, there was a simple linear correlation between the catalase activity and flux from [14C]ethanol into lipid. By feeding alcohols simultaneously with 3AT, ethanol and methanol were shown to react efficiently with catalase in wild-type larvae at moderately low dietary concentrations. Drosophila catalase did not react with other longer chain alcohols. Catalase apparently represents a minor pathway for ethanol degradation in D. melanogaster larvae, but it may be an important route for methanol elimination from D. melanogaster larvae.