A GASTRIC ALCOHOL-DEHYDROGENASE IN THE BABOON - PURIFICATION AND PROPERTIES OF A HIGH-KM ENZYME, CONSISTENT WITH A ROLE IN 1ST 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.