White B A, Lipsky R L, Fricke R J, Hylemon P B
Steroids. 1980 Jan;35(1):103-9. doi: 10.1016/0039-128x(80)90115-4.
The addition of cholic acid to growing cultures of Eubacterium species V.P.I. 12708 caused a 25 and 46-fold increase in 7 alpha-dehydroxylation activity using cell extracts or whole cell suspensions, respectively. Bile acid conversion rates using either [14C]-cholic acid or [14C]-chenodeoxycholic acid as substrates increased at approximately the same rate when either cholic or chenodeoxycholic acid was added to growing cultures as inducer. The induction of 7 alpha-dehydroxylase activity was highly specific requiring a free C-24-carboxyl group and an unhindered 7 alpha-hydroxy group on the B ring of the steroid nucleus. Unexpectedly, cholic acid also rapidly induced NADH:flavin oxidoreductase activity in growing cultures of this bacterium.
向生长中的真杆菌属V.P.I. 12708培养物中添加胆酸，分别使用细胞提取物或全细胞悬浮液时，7α-脱羟基活性提高了25倍和46倍。当向生长中的培养物中添加胆酸或鹅去氧胆酸作为诱导剂时，以[14C]-胆酸或[14C]-鹅去氧胆酸为底物的胆汁酸转化率以大致相同的速率增加。7α-脱羟基酶活性的诱导具有高度特异性，需要甾体核B环上有一个游离的C-24羧基和一个不受阻碍的7α-羟基。出乎意料的是，胆酸还能在该细菌的生长培养物中迅速诱导NADH：黄素氧化还原酶活性。
