InterPro

Alcohol dehydrogenase (EC:1.1.1.1) (ADH) catalyzes the reversible oxidation of ethanol to acetaldehyde with the concomitant reduction of NAD: Ethanol + NAD = Acetaldehyde + NADH Currently three structurally and catalytically different types of alcohol dehydrogenases are known:

1. Zinc-containing 'long-chain' alcohol dehydrogenases.
2. Insect-type, or 'short-chain' alcohol dehydrogenases.
3. Iron-containing alcohol dehydrogenases.

Zinc-containing ADH's [PMID: 3622514, PMID: 1593644] are dimeric or tetrameric enzymes that bind two atoms of zinc per subunit. One of the zinc atom is essential for catalytic activity while the other is not. Both zinc atoms are coordinated by either cysteine or histidine residues; the catalytic zinc is coordinated by two cysteines and one histidine. Zinc-containing ADH's are found in bacteria, mammals, plants, and in fungi. In most species there are more than one isozyme (for example, human have at least six isozymes, yeast have three, etc.).

A number of other zinc-dependent dehydrogenases are closely related to zinc ADH [PMID: 8504864] and are included in this family, including xylitol dehydrogenase (EC:1.1.1.9); sorbitol dehydrogenase (EC:1.1.1.14); aryl-alcohol dehydrogenase (EC:1.1.1.90); threonine 3-dehydrogenase (EC:1.1.1.103); cinnamyl-alcohol dehydrogenase (EC:1.1.1.195) (CAD); galactitol-1-phosphate dehydrogenase (EC:1.1.1.251); and Pseudomonas putida 5-exo-alcohol dehydrogenase (EC:1.1.1).