酸盐还原酶的光谱和计算研究:质子诱导的电子转移和回键对反应性的贡献
Somdatta Ghosh1, Abhishek Dey, Yan Sun
1Department of Chemistry, Stanford University, Stanford, California 94305, USA.
质子化触发了 Rhodobacter sphaeroides 酸盐减少酶中的电子转移,导致了 NO 的产生. 双酸酸与铜结合,激活了结合裂变,这对于酸减少至关重要.
科学领域:
- 生物化学和生物物理学
- 生物有机化学 生物有机化学
- 计算化学计算化学
背景情况:
- 来自Rhodobacter sphaeroides的酸盐还原酶 (NiR) 含有1型 (T1) 和2型 (T2) 铜中心.
- T2铜部位结合化物,这是减少的基质.
- 了解化物减少的机制对于酶功能至关重要.
研究的目的:
- 为了阐明尼罗河地区酸盐结合的T2铜部位的几何和电子结构.
- 研究依赖pH的化物减少机制,包括电子转移和N-O键裂解.
- 确定酸盐结合和铜协调在催化过程中的作用.
主要方法:
- 组合实验技术:光谱 (例如,UV-Vis,EPR) 来探测铜中心.
- 理论计算:密度函数理论 (DFT) 来建模电子结构和反应路径.
- 以pH值为依赖的研究,将质子化状态与酶活性和电子转移相关联.
主要成果:
- 在高pH下,没有从减少的T1转移到酸盐结合的T2铜.
- 低pH值的质子化触发了从T1到T2的电子转移,从而启动了NO的产生.
- DFT计算显示,质子转移先于并触发了N-O债券裂变的电子转移.
- 双酸与铜的结合是激活减少性裂变的关键,涉及背接和产品稳定.
结论:
- 通过NiR减少酸盐的机制涉及一个质子合电子转移过程.
- 对T2铜部位的双酸酸协调对于催化是必不可少的.
- 这种依赖pH的行为对于调节电子转移和NO形成至关重要.
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