Akao T, Akao T, Hattori M, Namba T, Kobashi K
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Biochim Biophys Acta. 1987 Sep 25;921(2):275-80.
Ruminococcus sp. PO1-3 from human intestinal flora reduced dehydrocholic acid to 3 beta-hydroxy-7,12-dioxo-5 beta-cholanic acid by means of the enzyme 3 beta-hydroxysteroid dehydrogenase (Akao, T., Akao, T., Hattori, M., Namba, T. and Kobashi, K. (1986) J. Biochem. (Tokyo) 99, 1425-1431). This bacterium and its crude extract gave rise to another product, showing a lower RF value on TLC, from dehydrocholic acid. The product was identified as 3 beta, 7 beta-dihydroxy-12-oxo-5 beta-cholanic acid. The crude extract reduced 7-ketolithocholic acid and its methyl ester, but not 6-ketolithocholic acid and 12-ketochenodeoxycholic acid, in the presence of NADPH, and oxidized ursodeoxycholic acid and beta-muricholic acid, but not cholic acid, chenodeoxycholic acid, deoxycholic acid and hydrocholic acid, in the presence of NADP+. Therefore, besides 3 beta-hydroxysteroid dehydrogenase, 7 beta-hydroxysteroid dehydrogenase was shown to be present in this bacterium. The two dehydrogenases were clearly separated from each other by butyl-Toyopearl 650 M column chromatography. From dehydrocholic acid, 7 beta-hydroxy-3,12-dioxo-5 beta-cholanic acid was produced by 7 beta-hydroxysteroid dehydrogenase and 3 beta, 7 beta-dihydroxy-12-oxo-5 beta-cholanic acid was produced by combination of two enzymes, 7 beta- and 3 beta-hydroxysteroid dehydrogenase.
来自人类肠道菌群的瘤胃球菌属PO1-3通过3β-羟基类固醇脱氢酶将脱氢胆酸还原为3β-羟基-7,12-二氧代-5β-胆烷酸（赤尾，T.，赤尾，T.，服部，M.，难波，T.和小林，K.（1986年）《生物化学杂志》（东京）99，1425 - 1431）。该细菌及其粗提物从脱氢胆酸产生了另一种在薄层色谱上Rf值较低的产物。该产物被鉴定为3β,7β-二羟基-12-氧代-5β-胆烷酸。在NADPH存在的情况下，粗提物还原了7-酮石胆酸及其甲酯，但不还原6-酮石胆酸和12-酮鹅去氧胆酸；在NADP⁺存在的情况下，氧化了熊去氧胆酸和β-鼠胆酸，但不氧化胆酸、鹅去氧胆酸、脱氧胆酸和氢化胆酸。因此，除了3β-羟基类固醇脱氢酶外，该细菌中还存在7β-羟基类固醇脱氢酶。通过丁基-Toyopearl 650 M柱色谱法可将这两种脱氢酶清晰地分离。由脱氢胆酸，7β-羟基-3,12-二氧代-5β-胆烷酸由7β-羟基类固醇脱氢酶产生，3β,7β-二羟基-12-氧代-5β-胆烷酸由7β-和3β-羟基类固醇脱氢酶这两种酶共同作用产生。
