title: Structural and functional comparison of two human liver dihydrodiol dehydrogenases associated with 3 alpha-hydroxysteroid dehydrogenase activity.
abstract: Two monomeric dihydrodiol dehydrogenases with pI values of 5.4 and 7.6 were co-purified with androsterone dehydrogenase activity to homogeneity from human liver. The two enzymes differed from each other on peptide mapping and in their heat-stabilities; with respect to the latter the dihydrodiol dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase activities of the respective enzymes were similarly inactivated. The pI 5.4 enzyme was equally active towards trans- and cis-benzene dihydrodiols, and towards (S)- and (R)-forms of indan-1-ol and 1,2,3,4-tetrahydronaphth-1-ol and oxidized the 3 alpha-hydroxy group of C19-, C21- and C24-steroids, whereas the pI 7.6 enzyme showed high specificity for trans-benzene dihydrodiol, (S)-forms of the alicyclic alcohols and C19- and C21-steroids. Although the two enzymes reduced various xenobiotic carbonyl compounds and the 3-oxo group of C19- and C21-steroids, and were A-specific in the hydrogen transfer from NADPH, only the pI 5.4 enzyme showed reductase activity towards 7 alpha-hydroxy-5 beta-cholestan-3-one and dehydrolithocholic acid. The affinity of the two enzymes for the steroidal substrates was higher than that for the xenobiotic substrates. The two enzymes also showed different susceptibilities to the inhibition by anti-inflammatory drugs and bile acids. Whereas the pI-5.4 enzyme was highly sensitive to anti-inflammatory steroids, showing mixed-type inhibitions with respect to indan-1-ol and androsterone, the pI 7.6 enzyme was inhibited more potently by non-steroidal anti-inflammatory drugs and bile acids than by the steroidal drugs, and the inhibitions were all competitive. These structural and functional differences suggest that the two enzymes are 3 alpha-hydroxysteroid dehydrogenase isoenzymes.
authors.affiliation: Department of Biochemistry, Gifu Pharmaceutical University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Deyashiki
authors.forename: H
authors.initials: H
authors.lastname: Taniguchi
authors.forename: T
authors.initials: T
authors.lastname: Amano
authors.forename: T
authors.initials: T
authors.lastname: Nakayama
authors.forename: A
authors.initials: A
authors.lastname: Hara
authors.forename: H
authors.initials: H
authors.lastname: Sawada
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D000328:Adult; D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001647:Bile Acids and Salts / Q000494:pharmacology; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008297:Male; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000502:physiology; D044925:Oxidoreductases Acting on CH-CH Group Donors
chemical_list: D000893:Anti-Inflammatory Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D001647:Bile Acids and Salts; D010088:Oxidoreductases; D015096:3-Hydroxysteroid Dehydrogenases; D000429:Alcohol Oxidoreductases; C023125:dihydrodiol dehydrogenases; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D044925:Oxidoreductases Acting on CH-CH Group Donors; C116788:cis-1,2-dihydro-1,2-dihydroxynaphthalene dehydrogenase