突变对类异构酶中的质子转移反应的影响:从分子动力学模拟的见解
Dhruva K Chakravorty1, Sharon Hammes-Schiffer
1Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Journal of the American Chemical Society
|May 11, 2010
概括
基固醇异构酶 (KSI) 活性部位残留物Tyr14和Asp99的突变通过破坏dienolate中间体的稳定性来降低催化速率. 模拟显示突变物中改变了键和静电相互作用,影响了质子转移效率.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 计算化学计算化学
背景情况:
- 固醇异构酶 (KSI) 催化了重要的质子转移反应.
- 来自Tyr14和Asp99的键稳定了野生型 (WT) KSI中的二烯酸盐中间体.
- 了解活性部位残留物的作用对于阐明酶机制至关重要.
研究的目的:
- 研究Tyr14和Asp99突变对KSI的催化机制的影响.
- 分析在质子转移期间的结合,构造和相互作用的变化.
- 为了将模拟结果与实验动力学数据相关联.
主要方法:
- 使用经验价值键 (EVB) 模型进行分子动力学 (MD) 模拟.
- 分析键模式,形态动力学和相互作用能量.
- 对质子转移步骤的自由能量概况和速率常数的计算.
主要成果:
- 突变Y14F和D99L显著增加了二烯酸盐中间体的自由能量,减少了第一个质子转移速率.
- WT KSI保持了两个活性位点键,而突变物通常只有一个,影响了中间稳定.
- 与WT KSI相比,突变体中中间体的静电稳定性降低了.
结论:
- 突变改变了KSI预先组织的活性部位结构,导致催化效率降低.
- 突变物中的改变的键和静电相互作用破坏了二烯酸盐中间体的稳定.
- 酶活性部位需要特定的结构动态来实现有效的催化,即使在预先组织的情况下也是如此.
相关概念视频
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