...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Induced fit and the catalytic mechanism of isocitrate dehydrogenase
【24h】

Induced fit and the catalytic mechanism of isocitrate dehydrogenase

机译：异柠檬酸脱氢酶的诱导拟合及其催化机理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

NADP ~+ dependent isocitrate dehydrogenase (IDH; EC 1.1.1.42) belongs to a large family of α-hydroxyacid oxidative β-decarboxylases that catalyze similar three-step reactions, with dehydrogenation to an oxaloacid intermediate preceding β-decarboxylation to an enol intermediate followed by tautomerization to the final α-ketone product. A comprehensive view of the induced fit needed for catalysis is revealed on comparing the first "fully closed" crystal structures of a pseudo-Michaelis complex of wild-type Escherichia coli IDH (EcoIDH) and the "fully closed" reaction product complex of the K100M mutant with previously obtained "quasi-closed" and "open" conformations. Conserved catalytic residues, binding the nicotinamide ring of NADP ~+ and the metal-bound substrate, move as rigid bodies during domain closure by a hinge motion that spans the central β-sheet in each monomer. Interactions established between Thr105 and Ser113, which flank the "phosphorylation loop", and the nicotinamide mononucleotide moiety of NADP ~+ establish productive coenzyme binding. Electrostatic interactions of a Lys100-Leu103-Asn115-Glu336 tetrad play a pivotal role in assembling a catalytically competent active site. As predicted, Lys230* is positioned to deprotonate/reprotonate the α-hydroxyl in both reaction steps and Tyr160 moves into position to protonate C3 following β-decarboxylation. A proton relay from the catalytic triad Tyr160-Asp307-Lys230* connects the α-hydroxyl of isocitrate to the bulk solvent to complete the picture of the catalytic mechanism.
机译：依赖NADP〜+的异柠檬酸脱氢酶（IDH; EC 1.1.1.42）属于一个大的α-羟酸氧化β-脱羧酶家族，催化类似的三步反应，先将草酸脱氢为草酸中间体，然后再进行β-脱羧为烯醇中间体。通过互变异构化成最终的α-酮产物。通过比较野生型大肠杆菌IDH（EcoIDH）的拟Michaelis配合物和K100M的“完全关闭”反应产物配合物的第一个“完全关闭”晶体结构，可以全面了解催化所需的诱导拟合。具有先前获得的“准封闭”和“开放”构象的突变体。结合NADP〜+的烟酰胺环和与金属结合的底物的保守催化残基在域闭合期间通过跨越每个单体中心β-折叠的铰链运动而作为刚性体移动。在位于“磷酸化环”侧翼的Thr105和Ser113之间建立的相互作用与NADP〜+的烟酰胺单核苷酸部分建立了有效的辅酶结合。 Lys100-Leu103-Asn115-Glu336四元体的静电相互作用在组装催化活性位点中起着关键作用。如所预测的，Lys230 *被定位为在两个反应步骤中使α-羟基去质子化/再质子化，而Tyr160进入位置以在β-脱羧后质子化C3。来自催化三联体Tyr160-Asp307-Lys230 *的质子中继将异柠檬酸的α-羟基连接到本体溶剂上，以完成催化机理的描述。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号