SUBSTRATE BINDING AND CATALYSIS BY GLUTATHIONE-REDUCTASE AS DERIVED FROM REFINED ENZYME - SUBSTRATE CRYSTAL-STRUCTURES AT 2A RESOLUTION
SUBSTRATE BINDING AND CATALYSIS BY GLUTATHIONE-REDUCTASE AS DERIVED FROM REFINED ENZYME - SUBSTRATE CRYSTAL-STRUCTURES AT 2A RESOLUTION
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DOI：
10.1016/0022-2836(89)90298-2
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发表时间：
1989-11-05
影响因子：
5.6
通讯作者：
SCHULZ, GE
中科院分区：
文献类型：
--
作者：
KARPLUS, PA;SCHULZ, GE
四种谷胱甘肽还原酶配合物及其衍生物的x射线结构分析已扩展到2 . ang。决议和细化。结果与已知1.54 . ang的氧化天然酶的结构一起进行了讨论。决议。而剩余坐标误差在0.2 . ang左右。，即使在这个范围内也可以确定一些重大变化。特别感兴趣的是3.2 . ang。烟酰胺C4N对黄素N5F氢化物转移几何的探讨。NADPH的2 " -磷酸氢键的几何形状与NADH结合的无机磷酸盐的几何形状的比较，由精细原子温度因素得出的底物部分的不同迁移率，以及邻近残基的构象变化以及黄素对近端Cys63的硫酸盐的稳定。此外，具有催化活性的His467”与谷胱甘肽- 1的硫的相互作用比与Cys58的远端硫的相互作用更理想。观察到水分子参与NADPH和谷胱甘肽的结合是如此广泛，仅从多肽结构预测结合模式将是非常困难的。精确已知的几何形状使我们能够对酶的机制得出一些结论，并提出了催化的可能情况。
The X-ray structure analyses of four glutathione reductase complexes and derivatives have been extended to 2 .ANG. resolution and refined. The results are discussed in conjunction with the structure of the oxidized native enzyme known at 1.54 .ANG. resolution. While the residual co-ordinate errors are around 0.2 .ANG., some significant shifts even in this range could be established. Points of particular interest are the 3.2 .ANG. approach of C4N of nicotinamide to N5F of flavin in hydride transfer geometry. The hydrogen bond geometries of the 2''-phosphate of NADPH as compared to inferior geometries for an inorganic phosphate binding together with NADH, the differential mobilities of parts of the substrates as derived from refined atomic temperature factors, and the stabilization of the thiolate of the proximal Cys63 by conformational changes of neighboring residues as well as by flavin. In addition, catalytically competent His467'' is seen to interact more optimally with the sulfur of glutathione-I than with the distal sulfur of Cys58. The observed participation of water molecules for both NADPH and glutathione binding is so extensive that a prediction of the binding mode merely from the polypeptide structure would be very difficult. The accurately known geometries allowed us to draw some conclusions on the enzyme mechanism and suggest a possible scenario of the catalysis.