Purification and Characterization of Liver Carbonyl Reductase in the Japanese Monkey

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Abstract
Two aldehyde reductases and carbonyl reductases from Japanese monkey liver cytosol were purified; the 2 aldehyde reductases obtained were to be homogeneous, while the carbonyl reductases were heterogeneous on polyacrylamide gel electrophoresis. A major aldehyde reductase, which is a dimer of single subunits with a MW of 41,000, reduces aromatic and aliphatic aldehydes with NADH as a more preferable cofactor than NADPH, and is inhibited by pyrazole and o-phenanthroline. The enzyme oxidizes alcohols in the presence of NAD+ as a cofactor. The other monomeric aldehyde reductase with MW of 36,000 is a high-Km aldehyde reductase which reduces aldehydes, D-glucuronate and .alpha.-diketones and which is sensitive to diphenylhydantoin and phenobarbital. The enzyme is not only immunologically identical with human liver aldehyde reductase, but its amino acid composition also closely resembles that of the human liver enzyme. The 2 carbonyl reductases show similar low substrate specificity for aldehydes, ketones and quinones. One enzyme with a MW of 80,000 shows dual cofactor specificity for NADH and NADPH and is selectively inhibited by isobutyramide, whereas another enzyme with MW of 32,500 exhibits absolute cofactor specificity for NADPH and sensitivity to ethacrynic acid and p-chloromercuribenzoic acid.