节细菌属D-xylose异构酶的结构应变B3728含有抑制剂木糖醇、山梨糖醇分辨率2.5和2.3,分别。
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节细菌属D-xylose异构酶的结构应变B3728含有抑制剂木糖醇、山梨糖醇分辨率2.5和2.3,分别。
J杂志。1989年7月5日,208 (1):129 - 57。
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2769749 (在PubMed]
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D-xylose异构酶的结构节细菌属菌株含有多元醇抑制剂B3728木糖醇、山梨糖醇已经解决了在2.5和2.3,分别。结构已经使用约束最小二乘优化方法精制。山梨糖醇的最终结晶r个因子(木糖醇)结合分子,43615(32989)反射是15.6 (14.7)。是四聚物分子和晶体的不对称单元包含一个二聚体,最终的模型,包含6086独特的蛋白质、抑制剂和镁原子一起535绑定溶剂分子。每个酶亚基包含两个域:主域名是parallel-strandedα-β桶,已报道的其他14酶。c端结构域是一个循环组成的五个螺旋段和参与分子间接触单元构成四聚物。分析了对分子的结构对称,intersubunit联系人、抑制剂绑定和活性部位几何。精致的模型显示了两个独立的子单元相似,除了当地solvent-exposed螺旋偏差由于溶剂接触。酶是依赖于二价阳离子催化活性。每个单体两个金属离子是必需的,和高亲和性镁(II)站点已被确认的结构给出结果。 The metal ion is complexed, at the high-affinity site, by four carboxylate side-chains of the conserved residues, Glu180, Glu216, Asp244 and Asp292. The inhibitor polyols are bound in the active site in an extended open chain conformation and complete an octahedral co-ordination shell for the magnesium cation via their oxygen atoms O-2 and O-4. The active site lies in a deep pocket near the C-terminal ends of the beta-strands of the barrel domain and includes residues from a second subunit. The tetrameric molecule can be considered to be a dimer of "active" dimers, the active sites being composed of residues from both subunits. The analysis has revealed the presence of several internal salt-bridges stabilizing the tertiary and quaternary structure. One of these, between Asp23 and Arg139, appears to play a key role in stabilizing the active dimer and is conserved in the known sequences of this enzyme.(ABSTRACT TRUNCATED AT 400 WORDS)