催化能力:S-O分裂硫酸酶的极端情况
David R Edwards1, Danielle C Lohman, Richard Wolfenden
1Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA. dredward@email.unc.edu
Journal of the American Chemical Society
|November 18, 2011
概括
硫酸盐单酶是强大的生物催化剂,可以实现硫酸盐水解的速度提升高达2 × 10^26倍. 这超越了酸酶,澄清了硫酸盐与酸单的明显反应性.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 化学动力学 化学动力学
背景情况:
- 硫酸盐单酶是催化硫酸盐单的水解的酶.
- 了解它们的催化功率需要与自发水解速率进行比较.
- 生物催化剂的先前基准,如酸酶,显示速度增强高达10^21倍.
研究的目的:
- 通过S-O键裂解来确定未激活的硫酸基单的自发水解速率.
- 建立基准来判断硫酸盐单酶的催化效率.
- 为了比较硫酸盐单与酸盐单的活性.
主要方法:
- 研究了自发的硫酸氨酸单水解 (S-O裂变) 的温度依赖性.
- 使用布朗斯特德图表将水解速率常数与pK (a) (LG) 值相关联.
- 额外推算的速率常数,以估计性酒精类离开组的自发水解速率.
主要成果:
- 确定酸硫酸单的自发水解速率常数 (k(25) ((N)) 为 3 × 10(-26) s(-1).
- 细菌硫酸酶的催化速率增强 (k ((cat) /k ((uncat)) 高达2 × 10^26倍.
- 硫酸盐单水解通过硫酸酶显著比酸酶催化更有效.
结论:
- 硫酸盐单酶是已知的最强大的生物催化剂之一,比酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸酸.
- 这项研究消除了硫酸盐和酸盐单具有相似的水解反应活性的概念.
- 硫酸酶实现了非凡的速率提升,突出了它们至关重要的生物作用.
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