CHARACTERIZATION OF NAD-DEPENDENT 3-ALPHA-HYDROXYSTEROID AND 3-BETA-HYDROXYSTEROID DEHYDROGENASE AND OF NADP-DEPENDENT 7-BETA-HYDROXYSTEROID DEHYDROGENASE FROM PEPTOSTREPTOCOCCUS-PRODUCTUS
CHARACTERIZATION OF NAD-DEPENDENT 3-ALPHA-HYDROXYSTEROID AND 3-BETA-HYDROXYSTEROID DEHYDROGENASE AND OF NADP-DEPENDENT 7-BETA-HYDROXYSTEROID DEHYDROGENASE FROM PEPTOSTREPTOCOCCUS-PRODUCTUS
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DOI：
10.1016/0005-2760(89)90272-5
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发表时间：
1989-08-08
期刊：
影响因子：
--
通讯作者：
HAMMANN, R
中科院分区：
文献类型：
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作者：
EDENHARDER, R;PFUTZNER, A;HAMMANN, R
通过形态学、生理学和生物化学数据表征为短消化链霉菌菌株的人粪便分离物显示含有NAD依赖性3 α- 3. beta.-羟基类固醇脱氢酶和NADP依赖性7 β-羟基类固醇脱氢酶所有的酶活性可以证明在粗提物和膜馏分。3.alpha 3. beta.-组成型地合成羟基类固醇脱氢酶。当细菌在3-酮基胆汁酸存在下生长时，特定的酶活性显著降低，而其他胆汁酸则无效。对于3.alpha。（3 β）─羟基类固醇脱氢酶的最适pH值为8.5（9.5），分子量为95000（132000）。3.alpha.- 3. beta.-羟基类固醇脱氢酶是热敏的（在50 ℃下10分钟约75%失活）。7.beta.-羟基类固醇脱氢酶已经存在于未诱导的细胞中，但是当细菌在7-酮胆汁酸存在下生长时，比活性可以增强高达2.5倍以上。二取代胆汁酸比三取代胆汁酸更有效，熊去氧胆酸作为诱导剂无效。对于7 β-β-葡聚糖，显示出10.0的最适pH和约82000的分子量。羟基类固醇脱氢酶该酶制剂减少了相应胆汁酸的7-酮基。再次，二取代的胆汁酸的酶的亲和力高于那些的三取代的胆汁酸，但没有显着差异，共轭和游离胆汁酸观察。7.beta.-羟基类固醇脱氢酶是热敏感的（在50 ℃下10分钟72%失活），但在4 ℃下至少48小时可检测到。
A human fecal isolate, characterized by morphological, physiological and biochemical data as a strain of Peptostreptococcus roductus, was shown to contain NAD-dependent 3.alpha.- and 3.beta.-hydroxysteroid dehydrogenases and a NADP-dependent 7.beta.-hydroxysteroid dehydrogenase. All enzyme activities could be demonstrated in crude extracts and in membrane fractions. The 3.alpha.- and 3.beta.-hydroxysteroild dehydrogenases were synthesized constitutively. Specific enzymatic activities were significantly reduced when bacteria were grown in the presence of 3-keto bile acids, while other bile acids were ineffective. For the 3.alpha.(3.beta.)-hydroxysteroid dehydrogenase, a pH optimum of 8.5 (9.5) and a molecular weight of 95000 (132000) was estimated. 3.alpha.- and 3.beta.-hydroxysteroid dehydrogenases were heat-sensitive (about 75% inactivation at 50.degree.C for 10 min). The 7.beta.-hydroxysteroid dehydrogenase was already present in uninduced cells, but specific activity could be enhanced up to more than 2.5-fold when bacteria were grown in the presence of 7-keto bile acids. Disubstituted bile acids were more effective than trisubstituted ones, ursodeoxycholic acid was ineffective as an inducer. A pH optimum of 10.0 and a molecular weight of about 82000 were shown for the 7.beta.-hydroxysteroid dehydrogenase. The enzyme preparation reduced the 7-keto group of corresponding bile acids. Again the affinities of disubstituted bile acids for the enzyme were higher than those of the trisubstituted bile acids, but no significant differences between conjugated and free bile acids were observed. The 7.beta.-hydroxysteroid dehydrogenase was heat-sensitive (72% inactivation at 50.degree.C for 10 min), but was detectable at 4.degree.C for at least 48 h.