...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >The Temperature Dependence of the Kinetic Isotope Effects of Dihydrofolate Reductase from Thermotoga maritima Is Influenced by Intersubunit Interactions
【24h】

The Temperature Dependence of the Kinetic Isotope Effects of Dihydrofolate Reductase from Thermotoga maritima Is Influenced by Intersubunit Interactions

机译：来自Thermotoga Maritima的二氢酚酸盐还原酶的动力学同位素效应的温度依赖性受到梭菌相互作用的影响

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

Dihydrofolate reductase from the hyperthermophile Thermotoga maritima (TmDHFR) is unique among structurally characterized chromosomal DHFRs in that it forms a stable homodimer. Dimerization is believed to play a key role in the high thermal stability of TmDHFR, which is reflected in a melting temperature in excess of 85 degrees C. The dimer interface of TmDHFR is composed of a hydrophobic core with charged residues around the periphery. In particular, Lys129 of each subunit forms three-membered salt bridges with Glu136 and Glu138 of the other subunit. To probe the role of these salt bridges in the dimerization and thermal stability of TmDHFR, we generated a series of variants (TmDHFR-K129E, TmDHFR-E136K, TmDHFR-E138K, and TmDHFR-E136K/E138K) in which these residues were exchanged for residues whose side chains bear the opposite charge. Our results indicate that these salt bridges are key for the high thermal stability of TmDHFR but are not a requirement for dimerization. Although the rate of dihydrofolate reduction by TmDHFR is not significantly affected by the loss of the K129-E136-E138 salt bridges, changes to the temperature dependence of the kinetic isotope effect on hydride transfer are observed. These changes are in agreement with the proposal that DHFR catalysis may be affected by changes to the conformational ensemble of the enzyme rather than only to the coupling of protein motions to the reaction coordinate.
机译：来自高嗜热嗜热疗法的二氢醇还原酶（TMDHFR）在结构表征染色体DHFR中是独特的，因为它形成稳定的同型二聚体。认为二聚化在TMDHFR的高热稳定性中发挥关键作用，其在过量超过85℃的熔化温度中反映。TMDHFR的二聚体界面由疏水芯构成，疏水芯，周边周围带带电残余物。特别地，每个亚基的Lys129与其他亚基的Glu136和Glu138形成三元盐桥。探讨这些盐桥在TMDHFR的二聚化和热稳定性中的作用，我们产生了一系列变体（TMDHFR-K129E，TMDHFR-E136K，TMDHFR-E138K和TMDHFR-E136K / E138K，其中换了这些残留物侧链承受相反电荷的残留物。我们的结果表明，这些盐桥是TMDHFR的高热稳定性的关键，但不是二聚化的要求。尽管通过TMDHFR的二氢溶胶酸盐率没有显着影响K129-E136-E138盐桥的损失，但观察到动力学同位素效应对氢化物转移的温度依赖性的变化。这些变化与该提议一致，即DHFR催化可能受酶的构象集合的变化影响而不是蛋白质动作与反应坐标的偶联的影响。

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