3-DIMENSIONAL STRUCTURE OF HOLO 3-ALPHA,20-BETA-HYDROXYSTEROID DEHYDROGENASE - A MEMBER OF A SHORT-CHAIN DEHYDROGENASE FAMILY
3-DIMENSIONAL STRUCTURE OF HOLO 3-ALPHA,20-BETA-HYDROXYSTEROID DEHYDROGENASE - A MEMBER OF A SHORT-CHAIN DEHYDROGENASE FAMILY
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DOI：
10.1073/pnas.88.22.10064
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发表时间：
1991-11-01
影响因子：
11.1
通讯作者：
ORR, JC
中科院分区：
文献类型：
--
作者：
GHOSH, D;WEEKS, CM;ORR, JC
短链脱氢酶，细菌holo 3- α，20- β -羟基类固醇脱氢酶（EC 1.1.1.53）的x射线结构在2.6埃分辨率下被描述。这种酶以四聚体的形式活跃，在不对称单元中有四个相同的亚基结晶。它具有二核苷酸结合区的α / β折叠特征。然而，亚基的其余部分的折叠，四元结构以及辅因子-酶相互作用的性质与长链脱氢酶中观察到的明显不同。假设活性位点的结构与观察到的酶的立体特异性和四聚体是活性形式的事实是一致的。每个亚基只有一个辅因子和一个底物结合位点；类固醇的3- α端和20- β端都具有特异性，这是由于类固醇在同一催化位点的同一辅因子附近以两个方向结合。
The x-ray structure of a short-chain dehydrogenase, the bacterial holo 3-alpha,20-beta-hydroxysteroid dehydrogenase (EC 1.1.1.53), is described at 2.6 angstrom resolution. This enzyme is active as a tetramer and crystallizes with four identical subunits in the asymmetric unit. It has the alpha/beta-fold characteristic of the dinucleotide binding region. The fold of the rest of the subunit, the quarternary structure, and the nature of the cofactor-enzyme interactions are, however, significantly different from those observed in the long-chain dehydrogenases. The architecture of the postulated active site is consistent with the observed stereospecificity of the enzyme and the fact that the tetramer is the active form. There is only one cofactor and one substrate-binding site per subunit; the specificity for both 3-alpha- and 20-beta-ends of the steroid results from the binding of the steroid in two orientations near the same cofactor at the same catalytic site.