Groman E V, Schultz R M, Engel L L, Orr J C
Eur J Biochem. 1976 Apr 1;63(2):427-9. doi: 10.1111/j.1432-1033.1976.tb10244.x.
In the reduction of 17beta-hydroxy-5alpha-androstan-3-one to the 3beta-alcohol, horse liver alcohol dehydrogenase utilizes the 4-pro-R hydrogen of NADH whereas the 3(17)beta-hydroxysteroid dehydrogenase of Pseudomonas testosteroni utulized the 4-pro-S hydrogen. These observations provide an exception to the rule proposed by Alworth and Bentley that with regard to the paired methylene hydrogens at C-4 of NADH and NADPH "the stereospecificity of a particular reaction is fixed and does not vary with the source of the enzyme preparation". It is also apparent that for these two enzymes, the selection of the side of NADH from which hydride is transferred to substrate cannot in both cases be dictated by the "best fit" of substrate and cofactor.
在将17β-羟基-5α-雄甾烷-3-酮还原为3β-醇的过程中，马肝醇脱氢酶利用NADH的4-前-R氢，而睾丸酮假单胞菌的3(17)β-羟基类固醇脱氢酶利用4-前-S氢。这些观察结果为阿尔沃思和本特利提出的规则提供了一个例外，该规则认为，对于NADH和NADPH在C-4处的成对亚甲基氢，“特定反应的立体特异性是固定的，不会随酶制剂的来源而变化”。同样明显的是，对于这两种酶，在两种情况下，从NADH哪一侧转移氢化物到底物的选择都不能由底物和辅因子的“最佳匹配”来决定。
