Enzymatic characterization of a novel bovine liver dihydrodiol dehydrogenase - reaction mechanism and bile acid dehydrogenase activity
作者:Hirofumi Nanjo、Hideki Adachi、Shoko Morihana、Tadashi Mizoguchi、Tsutomu Nishihara、Tomoyuki Terada
DOI:10.1016/0304-4165(94)00195-4
日期:1995.5
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 K-m 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 anti taurochenodeoxycholic acid) having no 12-hydroxy groups with low K-m values (17 +/- 0.65, 33 +/- 1.9 and 890 +/- 73 mu M, 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.