在220K的动态过渡下,晶体核核糖酶A失去了功能
B F Rasmussen1, A M Stock, D Ringe
1Structural Biology Laboratory, Rosenstiel Basic Medical Sciences Research Center, Waltham, Massachusetts.
Nature
|June 4, 1992
概括
蛋白质动力学显示一个关键的过渡在220K左右.酶的灵活性对于功能至关重要,由基质结合在核糖酶A (RNaseA) 在温度高于这个过渡点证明.
科学领域:
- 生物物理学的生物物理.
- 结构生物学 结构生物学
- 酶学 是一种酶学.
背景情况:
- 蛋白质在不同温度下表现出双相动态行为,显著的转变在220K左右.
- 这种转变可以通过各种生物物理技术观察到,包括X射线晶体学,莫斯巴乌尔散射和中子散射.
研究的目的:
- 研究蛋白质灵活性在酶功能中的作用.
- 为了确定 A 核糖酶 (RNase A) 的依赖温度的结合特性.
主要方法:
- 高分辨率的X射线衍射被用来研究晶体核糖核酶A.
- 结合试验是在低于 (212 K) 和高于 (228 K) 观察到的动态过渡的温度下进行的.
- 分子动力学模拟也被用来理解不同温度下的原子运动.
主要成果:
- рибо核酶A (RNase A) 在212K时未能结合基质或抑制剂.
- 快速的基质和抑制剂结合发生在228K.
- 一旦在更高的温度下结合,即使在将酶冷却到过渡温度以下之后,抑制剂仍然保持结合.
结论:
- 酶的灵活性,特别是在220K过渡以上,对于基质和抑制剂的结合至关重要.
- 这些发现表明蛋白质动态和催化活性之间存在直接联系.
- 温度依赖的结合表明了酶功能所需的构造变化.
相关概念视频
The Nernst Equation
Nonstandard Reaction Conditions
The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous.
The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous.
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