精制1.54分辨率谷胱甘肽还原酶的结构。
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精制1.54分辨率谷胱甘肽还原酶的结构。
J杂志。1987年6月5日,195 (3):701 - 29。
- PubMed ID
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3656429 (在PubMed]
- 文摘
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人类建立了谷胱甘肽还原酶的晶体结构分辨率1.54使用约束最小二乘优化方法。基于77690的独立思考比10一项决议,18.6%获得模型的最后一个r因子服从标准几何在0.025债券长度和键角2.4度。最后2 fo-fc电子密度地图允许区别的碳,氮和氧原子与温度低于25 A2的因素。除了461氨基酸残基,辅基时尚,524年模型包含溶剂分子,大约118的可以被认为是酶的一个组成部分。最大的溶剂集群104二聚体界面和包含相互联系的溶剂分子,其中部分被组织在一个扭曲的片状结构。的主链二面角角度在允许的区域的拉玛钱德朗well-concentrated阴谋。二面角角度的传播beta-pleated表远远大于在阿尔法螺旋和特别是在阿尔法螺旋核心,指示beta-structures塑性就越高。分析了大量的3(10)螺旋。的侧链构象集群交错位置,并显示明确的偏好。此外,流动性梯度是侧链的观察。 Non-polar and polar side-chains show average temperature factor increases per bond of 10% and 25%, respectively. A number of alternative conformations of internal side-chains, in particular serines and methionines, have been detected. The extended FAD molecule also shows a mobility gradient between the very rigid flavin (mean value of B) = 8.7 A2) and the more mobile adenine (mean value of B = 16.2 A2). The entire active center is particularly well ordered, with temperature factors around 10 A2. The dimer interface consists of a rigid contact area, which is well conserved in the Escherichia coli enzyme, and a flexible area that is not. Altogether, the buried surfaces at the crystal contacts are half as large as at the dimer interface, but less specific. The refined structure shows clearly that there are no buried cations compensating the charge of the pyrophosphate moiety of FAD. The flavin deviates slightly from standard geometry, which is possibly caused by the polypeptide environment. In contrast to an earlier interpretation, atom N5 of the flavin can accommodate a proton, and it is conceivable that this proton proceeds to the redox-active disulfide.(ABSTRACT TRUNCATED AT 400 WORDS)