在P450模型复合体上进行硫K边缘XAS和DFT计算:结对电子结构和氧化还原潜力的影响
Abhishek Dey1, Taka-aki Okamura, Norikazu Ueyama
1Department of Chemistry, Stanford University, Stanford, California 94305, USA.
Journal of the American Chemical Society
|August 25, 2005
概括
键通过改变电子结构,显著影响蛋白质中的金属硫键. 这项研究量化了键如何调整P450模型中的铁-硫键共价性,使用SK边缘X射线吸收光谱学.
科学领域:
- 生物化学 生物化学
- 频谱学是一种光谱学.
- 计算化学的计算化学
背景情况:
- 结合对于调整金属蛋白活性位点中的电子结构和反应性至关重要.
- S K-边缘X射线吸收光谱 (XAS) 直接探测联金属键的共价性.
- 与模型复合体相比,蛋白质活性位表现出较少的共价金属-连接体键.
研究的目的:
- 量化评估结对P450模型复合物的金属硫结共价性的影响.
- 为了研究结,电子结构和氧化还原潜力之间的关系.
- 为了将光谱发现与计算分析相关联.
主要方法:
- 在具有不同结的P450模型复合体上使用了SK边缘X射线吸收光谱 (XAS).
- 进行密度函数理论 (DFT) 计算以建模电子和结构效应.
- 开发了一种债券分解分析,以将前边缘强度变化与Fe-S结合相互作用联系起来.
主要成果:
- S K-edge XAS 显示了前边强度的显著下降与增加的结合.
- DFT的计算证实了结,而不是诱导效应,导致了这些光谱变化.
- 结合主要以双极的方式影响Fe-S结合的共价性,在减少状态下影响更大.
结论:
- 结合显著调节Fe-S结合的共价性,影响蛋白质的反应性和氧化还原潜力.
- 观察到的协同变化可以通过SK边缘XAS前边缘强度直接测量.
- 观察到氧化还原潜力的260mV增加,与由于结合而改变的Fe-S键共价性相关.
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