J. Biochem, 1986, Vol. 99, No. 5 1425-1431
© 1986 Japanese Biochemical Society
research-article |
3ß-Hydroxysterod Dehydrogenase of Ruminococcus sp. from Human Intestinal Bacteria
*Faculty of Pharmaceutical Sciences Sugitani, Toyama, Toyama 93001
**Research Institute for Wakan-Yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University Sugitani, Toyama, Toyama 93001
Ruminococcus sp. PO1-3 obtained from human intestinal flora is able to reduce dehydrocholate as well as 3-ketoglycyrrhetinate. From this bacterium dehydrocholate- and 3-ketoglycyrrhetinate-reducing activities were purified one thousand fold together with 3-ketocholanate-reducing and 3ß-hydroxyglycyrrhetinate (glycyrrhetic acid) oxidizing activities by means of M
trex Red A, Sephadex G-200 and Octyl-Sepharose column chromatography. The purified enzyme catalyzed the reduction of dehydrocholic acid to ß-hydroxy-7,12-diketocholanic acid and of 3-ketocholanic acid to 3ß-hydroxycholanic acid. Studies on substrate specificity revealed that the enzyme had absolute specificity for the ß-configuration of a hydroxyl group at the 3 position of bile acid and steroids having no double bond in the A/B ring. This enzyme was neither ß-hydroxysteroid dehydrogenase [EC 1.1.1.51
[EC]
] nor 3ß-hydroxy-
5-steroid dehydrogenase [EC 1.1.1.145
[EC]
], but a novel type of enzyme, defined as 3ß-hydroxysteroid dehydrogenase.