Crystallographic and thermodynamic analysis of the binding of S-octylglutathione to the Tyr 7 to phe mutant of glutathione S-transferase from Schistosoma japonicum
Crystallographic and thermodynamic analysis of the binding of S-octylglutathione to the Tyr 7 to phe mutant of glutathione S-transferase from Schistosoma japonicum
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DOI：
10.1021/bi0483110
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发表时间：
2005-02-01
期刊：
影响因子：
2.9
通讯作者：
Cámara-Artigas, A
中科院分区：
文献类型：
--
作者：
Andújar-Sánchez, M;Smith, AW;Cámara-Artigas, A
谷胱甘肽s -转移酶是一个参与药物和外源代谢的多功能酶家族。位于酶活性位点的两个酪氨酸残基tyr7和tyr111在底物配体的结合和催化中起着重要作用。获得了日本血吸虫谷胱甘肽s -转移酶酪氨酸7到苯丙氨酸突变体[SjGST(Y7F)]与底物谷胱甘肽（GSH）和竞争抑制剂s -辛基谷胱甘肽（S-octyl-GSH）复合物的晶体结构。这些新的结构数据与荧光光谱和热力学数据相结合，通过等温滴定量热法获得，可以详细表征配体结合过程。s -辛基- gsh与SjGST（Y7F）的结合在低于30℃的温度下是焓和熵驱动的。结合的化学计量是每个突变二聚体一个s -辛基-谷胱甘肽分子，而较短的烷基衍生物结合的化学计量是每个突变二聚体两个分子。SjGST (Y7F)()。与野生型酶相比，谷胱甘肽的结构没有明显的差异。SjGST(Y7F)S-。-辛基- gsh与s -辛基- gsh表现出不对称结合。这种对称性的缺乏反映在SjGST(Y7F)S-的下对称空间群上。-辛基-谷胱甘肽晶体（P6(3)）与SjGST（Y7F）的比较（.）GSH晶体（P6(3)22）。此外，s -辛基-谷胱甘肽与A亚基的结合伴随着构象变化，这可能是导致与B亚基缺乏结合的原因。
Glutathione S-transferases are a family of multifunctional enzymes involved in the metabolism of drugs and xenobiotics. Two tyrosine residues, Tyr 7 and Tyr 111, in the active site of the enzyme play an important role in the binding and catalysis of substrate ligands. The crystal structures of Schistosoma japonicum glutathione S-transferase tyrosine 7 to phenylalanine mutant [SjGST(Y7F)] in complex with the substrate glutathione (GSH) and the competitive inhibitor S-octylglutathione (S-octyl-GSH) have been obtained. These new structural data combined with fluorescence spectroscopy and thermodynamic data, obtained by means of isothermal titration calorimetry, allow for detailed characterization of the ligand-binding process. The binding of S-octyl-GSH to SjGST(Y7F) is enthalpically and entropically driven at temperatures below 30degreesC. The stoichiometry of the binding is one molecule of S-octyl-GSH per mutant dimer, whereas shorter alkyl derivatives bind with a stoichiometry of two molecules per mutant dimer. The SjGST(Y7F)(.)GSH structure showed no major structural differences compared to the wild-type enzyme. In contrast, the structure of SjGST(Y7F)S-.-octyl-GSH showed asymmetric binding of S-octyl-GSH. This lack of symmetry is reflected in the lower symmetry space group of the SjGST(Y7F)S-.-octyl-GSH crystals (P6(3)) compared to that of the SjGST(Y7F)(.)GSH crystals (P6(3)22). Moreover, the binding of S-octyl-GSH to the A subunit is accompanied by conformational changes that may be responsible for the lack of binding to the B subunit.