Pedrini Paola, Andreotti Elisa, Guerrini Alessandra, Dean Mariangela, Fantin Giancarlo, Giovannini Pier Paolo
Dipartimento delle Risorse naturali e culturali, Università di Ferrara, C.so Ercole I d'Este 32, I-44100 Ferrara, Italy.
Steroids. 2006 Mar;71(3):189-98. doi: 10.1016/j.steroids.2005.10.002. Epub 2005 Nov 22.
The paper reports the partial purification and characterization of the 7beta- and 7alpha-hydroxysteroid dehydrogenases (HSDH) and cholylglycine hydrolase (CGH), isolated from Xanthomonas maltophilia CBS 897.97. The activity of 7beta-HSDH and 7alpha-HSDH in the reduction of the 7-keto bile acids is determined. The affinity of 7beta-HSDH for bile acids is confirmed by the reduction, on analytical scale, to the corresponding 7beta-OH derivatives. A crude mixture of 7alpha- and 7beta-HSDH, in soluble or immobilized form, is employed in the synthesis, on preparative scale, of ursocholic and ursodeoxycholic acids starting from the corresponding 7alpha-derivatives. On the other hand, a partially purified 7beta-HSDH in a double enzyme system, where the couple formate/formate dehydrogenase allows the cofactor recycle, affords 6alpha-fluoro-3alpha, 7beta-dihydroxy-5beta-cholan-24-oic acid (6-FUDCA) by reduction of the corresponding 7-keto derivative. This compound is not obtainable by microbiological route. The efficient and mild hydrolysis of glycinates and taurinates of bile acids with CGH is also reported. Very promising results are also obtained with bile acid containing raw materials.
本文报道了从嗜麦芽窄食单胞菌CBS 897.97中分离出的7β-和7α-羟基类固醇脱氢酶（HSDH）以及胆酰甘氨酸水解酶（CGH）的部分纯化及特性。测定了7β-HSDH和7α-HSDH在还原7-酮胆汁酸中的活性。通过在分析规模上还原为相应的7β-OH衍生物，证实了7β-HSDH对胆汁酸的亲和力。以可溶或固定化形式存在的7α-和7β-HSDH粗混合物，用于从相应的7α-衍生物出发，制备规模合成熊去氧胆酸和熊胆酸。另一方面，在双酶系统中，一种部分纯化的7β-HSDH与甲酸/甲酸脱氢酶对可使辅因子循环利用，通过还原相应的7-酮衍生物得到6α-氟-3α,7β-二羟基-5β-胆烷-24-酸（6-FUDCA）。该化合物无法通过微生物途径获得。还报道了利用CGH对胆汁酸甘氨酸盐和牛磺酸盐进行高效温和的水解。使用含胆汁酸的原料也获得了非常有前景的结果。
