A Gastric Alcohol Dehydrogenase in the Baboon: Purification and Properties of a ‘High‐K_m,’ Enzyme, Consistent with a Role in ‘First Pass’ Alcohol Metabolism

The major isozyme of alcohol dehydrogenase in baboon stomach, ADH3, has been purified to homogeneity and characterized with a range of alcohol and aldehyde substrates. Using K_cat/K_m, values as an indication of substrate efficacy, medium‐chain length aliphatic alcohols and aldehydes were identified as the preferred substrates. ADH3 showed ‘high‐K_m’ properties with respect to ethanol, and is expected to significantly contribute to ‘first‐pass’ metabolism of alcohol. The enzyme exhibited more than two orders of magnitude higher turnover of substrate than the baboon liver ‘low‐K_m’ ADH, and may play a role in the rapid metabolism of a wide range of ingested alcohols in the diet.