Aldehyde dehydrogenase, a diphosphopyridine nucleotide-linked enzyme.

The dismutation of acetaldehyde to ethyl alcohol and acetic acid has been shown to occur in animal tissues (1, 2). The dependence of this reaction on diphosphopyridine nucleotide was demonstrated by von Euler and Brunius (3). Partial purification of the responsible enzyme system was achieved by Dixon and Lutwak-Mann (4). These authors clearly demonstrated that the mutase activity was independent of aldehyde (xanthine) oxidase activity and proposed that aldehyde mutase should be considered aa a separate enzyme. This view has been accepted by recent text-books of enzymology in which the mutates are classified as separate enzymes (5, 6). It is the purpose of this paper to show that the dismutation of aldehydes in the liver tissue is catalyzed by two separable enzymes. One is the known alcohol dehydrogenase recently obtained in crystalline form from liver tissue (7). The other is an aldehyde dehydrogenase which will be described in this paper. Both of these enzymes have been found to be present in considerable quantities in aldehyde mutase preparations purified according to Dixon and Lutwak-Mann (4).