Abstract

The liver catalase inhibitor, 3-amino-1,2,4- triazole, does not affect ethanol oxidation in the rat, either in vivo or in vitro, while methanol oxidation by rat liver slices is inhibited more than 50%. Xanthine doubles the rate of methanol oxidation in vitro, but does not affect that of ethanol. These findings best fit the theory that all ethanol is oxidized by alcohol dehydrogenase while methanol is oxidized by catalase, acting as a peroxidase. In equimolar amounts, ethanol inhibits methanol metabolism in both the rat liver slice and in a pure beef catalase system by about one-half. Methanol does not inhibit ethanol oxidation in the liver slice, but in the pure beef catalase system some inhibition is seen. In the organism, ethanol probably inhibits methanol metabolism by competing for the active site on the enzyme catalase, but is not oxidized to a measurable extent by this enzyme. The possibility that other enzymes may be involved in methanol oxidation is not excluded.