在1型铜站点调整降低电位不会影响电子转移反应率
Sachiko Yanagisawa1, Christopher Dennison
1Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, UK.
Journal of the American Chemical Society
|November 25, 2005
概括
1型铜位点对于电子转移至关重要. 修改黄瓜基本蛋白质中的轴联体调整了反应性,表明较弱的协调增强了电子转移速率.
科学领域:
- 生物化学 生物化学
- 生物有机化学 生物有机化学
- 蛋白质科学 蛋白质科学
背景情况:
- 1型 (T1) 铜位点对于生物电子转移 (ET) 是至关重要的.
- 这些位点具有保存的His2Cys赤道连接体和可变的轴联接体,包括氨酸 (Met),谷氨酸 (Gln) 或缺乏连接体.
- 黄瓜的基本蛋白 (CBP) 是一种植物素 (PLT),具有T1铜位.
研究的目的:
- 研究轴联体变异对T1铜位的电子自我交换 (ESE) 速率常数和还原潜力的影响.
- 了解调节轴系协调环境如何影响CBP等蛋白质的内在ET反应性.
主要方法:
- 用局部导向的突变生成来创建CBP的Met89Gln和Met89Val变体.
- 测量了电子自我交换 (ESE) 速率常数 (k(ese)) 以评估内在的ET反应性.
- 测量了还原潜力,以评估铜部位电子性质的变化.
主要成果:
- 与野生类型相比,CBP的Met89Gln变异体现出k (((ese) 的约7倍减少.
- Met89Val 突变导致了 k (((ese) 的两倍增加.
- 减小轴相互作用强度 (Gln > Met > Val) 提高了ESE反应率大约一个数量级,并增加了约350mV的减少潜力.
结论:
- T1铜位点的轴协调环境显著影响ET反应性和减少潜力.
- 变量轴协调提供了一个调整ET驱动力的机制,以优化与生物伙伴的相互作用.
- 在三坐标T1铜位点的增强反应性,如在真菌laccases和Fet3p中看到的,可能促进了分子内ET.
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