酶增强合运动/量子力学气道化由类异构酶的实验证据
Thomas C Wilde1, Grzegorz Blotny, Ralph M Pollack
1Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA.
Journal of the American Chemical Society
|April 23, 2008
概括
这项研究研究了在酶和非酶反应中的量子力学道化 (HT). 结果表明,3-oxo-Delta(5) -类固醇异构酶 (KSI) 增强HT,有助于其催化速率的加速.
科学领域:
- 生物化学 生物化学
- 酶动力学 酶动力学
- 量子力学就是量子力学.
背景情况:
- 在酶和非酶系统中观察到量子力学道化 (HT).
- 与非酶反应相比,酶是否增强HT的数据有限.
研究的目的:
- 为了确定3-oxo-Delta(5) -类固醇异构酶 (KSI) 是否增强相对于乙酸催化反应的道化 (HT).
- 调查合运动/HT对KSI.速度加速的贡献.
主要方法:
- 在KSI和乙酸催化异构化中,测量了类固醇在C-6的α-二次动态同位素效应 (KIE).
- 在转移条件下通过测量二次KIE来评估合运动/HT的贡献.
- 分析了野生类型 (WT) KSI和活性位点突变 (Y14F,D99A) 的KIE数据.
主要成果:
- 对于WT KSI和酸盐的正常二次KIEs表明这两种系统中的运动/HT是合的.
- 在转移期间,WT KSI的二次KIE下降表明HT在酶反应中.
- 乙反应的二次KIE没有变化表明没有HT,这表明KSI增强了CM/HT.
- KSI活性部位突变显示KIEs与WT相似,这意味着结残留物对CM/HT贡献不至关重要.
结论:
- 与溶液反应相比,KSI增强了合运动/道化 (CM/HT) 对其催化速率加速的贡献.
- 酶的活性部位促进了增强的量子力学道化.
- 关键活性部位残留物的突变不会显著降低酶增强CM/HT的能力.
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