Dehydrogenase medium-chain alcohol

The final member of the yeast medium-chain alcohol dehydrogenase superfamily, encoded by the ZTA1 gene, differs in several key aspects from the six putative yeast reductases shown in Fig. 3A. Most important, this enzyme lacks the residues that ligate the catalytic Zn(II) ion, in common with other crystallin homologs. Related metal-free proteins are capable of reducing quinones [53] however, the catalytic activity and substrate specificity of the protein encoded by ZTA1 is currently unknown. 

The ALDs are a subset of the superfamily of medium-chain dehydrogenases/reductases (MDR). They are widely distributed, cytosolic, zinc-containing enzymes that utilize the pyridine nucleotide [NAD(P)+] as the catalytic cofactor to reversibly catalyze the oxidation of alcohols to aldehydes in a variety of substrates. Both endobiotic and xenobiotic alcohols can serve as substrates. Examples include (72) ethanol, retinol, other aliphatic alcohols, lipid peroxidation products, and hydroxysteroids (73). 

Catalytic Mechanism of Horse Liver Alcohol Dehydrogenase, a Medium-Chain Dehydrogenase... 

CAD is a type A reductase, abstracting the prol hydride from NADPH via a two-electron hydride transfer mechanism. It belongs to the alcohol dehydrogenase (ADH) family, the members of which are zinc-dependent medium-chain dehydrogenases/reductases (MDR) with two Zn ions per subunit. One zinc atom is thought to have a structural role, whereas the other forms the core of the catalytic site. Interestingly, medium-chain zinc-dependent ADHs exist as homotetramers as in bacteria, archaea, and yeast, or as homodimers as in plants and vertebrates. 

Table 25.1. Isozymes of Medium-ChaIn-Length Alcohol Dehydrogenases...

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