Biochemistry of methanol poisoning. III. The enzymic pathway for the conversion of methanol to formaldehyde.

Abstrsct—An enzyme system capable of oxidizing both methanol and ethanol in the 0 presence of DPN was purified almost nine ty-fold from the liver of the rhesus monkey. Data for theK, values for the two alcohols and DPN and for the R values in the presence of some inhibitors are presented. The enzyme ap rs to be identical to liver alcohol hydrogenase AD 1. Eihlili competitively inhibited the oxidation of methanol b y this enzyme. The purified enzyme had appreciable activity when, in place of DPN, TPN was used as the hydrogen-acceptor. Contrary to the observations of earlier authors, crystalline ADH, purified from horse liver, had an appreciable activity with methanol as substrate. The data on the elimination of methanol in the blood of monkeys administered methanol by stomach tube agrees with the rates of its oxidation, as observed in vitro. It is concluded that the dehydrogenase mechanism, and not the catalase-peroxide system, is responsible for the physiological oxidation of methanol.