title: Enzymatic characterization of a novel bovine liver dihydrodiol dehydrogenase--reaction mechanism and bile acid dehydrogenase activity.
abstract: Bovine liver cytosolic dihydrodiol dehydrogenase (DD3) has been characterized by its unique dihydrodiol dehydrogenase activity for trans-benzenedihydrodiol (trans-1,2-dihydrobenzene-1,2-diol) with the highest affinity and the greatest velocity among three multiple forms of dihydrodiol dehydrogenases (DD1-DD3). It is the first time that DD3 has shown a significant dehydrogenase activity for (S)-(+)-1-indanol with low Km value (0.33 +/- 0.022 mM) and high K(cat) value (25 +/- 0.79 min-1). The investigation of the product inhibition of (S)-(+)-1-indanol with NADP+ versus 1-indanone and NADPH clearly showed that the enzymatic reaction of DD3 may follow a typical ordered Bi Bi mechanism similar to many aldo/keto reductases. Additionally, DD3 was shown to catalyze the dehydrogenation of bile acids (lithocholic acid, taurolithocholic acid and taurochenodeoxycholic acid) having no 12-hydroxy groups with low Km values (17 +/- 0.65, 33 +/- 1.9 and 890 +/- 73 microM, respectively). In contrast, DD1, 3 alpha-hydroxysteroid dehydrogenase, shows a broad substrate specificity for many bile acids with higher affinity than those of DD3. Competitive inhibition of DD3 with androsterone against dehydrogenase activity for (S)-(+)-1-indanol, trans-benzenedihydrodiol or lithocholic acid suggests that these three substrates bind to the same substrate binding site of DD3, different from the case of human liver bile acid binder/dihydrodiol dehydrogenase (Takikawa, H., Stolz, A., Sugiyama, Y., Yoshida, H., Yamamoto, M. and Kaplowitz, N. (1990) J. Biol. Chem. 265, 2132-2136). Considering the reaction mechanism, DD3 may also play an important role in bile acids metabolism as well as the detoxication of aromatic hydrocarbons.
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Osaka University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nanjo
authors.forename: H
authors.initials: H
authors.lastname: Adachi
authors.forename: S
authors.initials: S
authors.lastname: Morihana
authors.forename: T
authors.initials: T
authors.lastname: Mizoguchi
authors.forename: T
authors.initials: T
authors.lastname: Nishihara
authors.forename: T
authors.initials: T
authors.lastname: Terada
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D002417:Cattle; D003600:Cytosol / Q000201:enzymology; D007189:Indans / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D009249:NADP / Q000494:pharmacology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D001647:Bile Acids and Salts; D007189:Indans; D009249:NADP; C013352:indacrinone; D010088:Oxidoreductases; C048338:trans-1,2-dihydrobenzene-1,2-diol dehydrogenase