在多中心酶中通过生物氧化还原链的电子转移机制
Lars J C Jeuken1, Anne K Jones, Stephen K Chapman
1Inorganic Chemistry Laboratory, Oxford University, South Parks Road, OX1 3QR, Oxford, United Kingdom.
Journal of the American Chemical Society
|May 16, 2002
概括
研究人员使用电化学研究了两种烟酸还原酶的分子内电子转移. 他们在电子转移机制中发现了差异,这表明在一个酶中存在超级交换,而在另一个酶中存在速度限制的电子转移.
科学领域:
- 生物化学 生物化学
- 电化学 电化学 电化学
- 酶动力学 酶动力学
背景情况:
- 多中心酶通过复杂的氧化还原链促进分子内电子转移 (IET).
- 了解IET机制对于酶功能和生物能量学至关重要.
- 烟酸还原酶 (FRs) 是无氧呼吸中的关键酶,涉及IET到它们的活性位点.
研究的目的:
- 研究和比较两种不同的烟酸还原酶中的IET机制:黄细胞染色体c(3) (Fcc(3) 和大肠杆菌烟酸还原酶复合体 (FrdAB).
- 利用方波电压测量 (SWV) 作为一种动力工具来探测电子传输路径和速率.
- 为了确定电子转移是直接发生的还是通过跳跃通过氧化还原因子.
主要方法:
- 活性烟酸还原酶在电极表面上的吸附.
- 方波电压测量 (SWV) 的应用,用于大幅度测量电子转移动力学.
- 作为超电位的函数的电子转移速率的动态建模.
- 实验数据与直接和跳跃电子转移模型的比较.
主要成果:
- 无论是Fcc(3) 还是FrdAB,都表现出电子转移到/从它们的埋藏活性位点.
- FrdAB的电子转移动力学与直接和跳跃机制一致.
- 最好的解释是直接的电子转移机制,可能涉及超级交换.
- 对于FrdAB,最大的电子转移速度与催化周转率相关,表明电子转移是限制速度的.
结论:
- 酶结构决定了主要的电子转移机制.
- 通过氧化还原链的超级交换可能会增强一些酶的电子合,如Fcc(3).
- 电子转移可以是酶催化过程中的速度限制步骤,正如FrdAB.所观察到的.
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