光化学核糖酶的α/β子单元界面上的电荷转移动力学
Lisa Olshansky1,2, JoAnne Stubbe1, Daniel G Nocera2
1Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|December 30, 2015
概括
核酸减少酶 (RNR) 使用一种新的光化学方法来研究DNA复制. 这项研究揭示了RNR如何控制电子和质子转移以实现高效的脱氧核酸合成.
科学领域:
- 生物化学
- 分子生物学
- 生物物理
背景情况:
- 核酸减少酶 (RNR) 对于DNA合成至关重要,通过质子合电子转移 (PCET) 催化脱氧核酸的产生.
- 由于形状变化缓慢,研究RNR中的快速PCET动力学具有挑战性.
- 开发了一种新型的光化学方法,使用 (I) 光氧化剂 (光β2) 来探测RNR的电子转移途径.
研究的目的:
- 在RNR中研究电子转移 (ET) 和质子转移 (PT) 的动力学和机制.
- 使用修改后的RNR绘制ET驱动力 (ΔG°) 和速率 (kET) 之间的相关性.
- 阐明RNR子单位在促进PCET中的作用.
主要方法:
- 在RNR的β2子单元上加入[Re(I]光氧化剂.
- 使用氨酸 (FnY) 变体对β-Y356进行光化学氧化以调节ET驱动力.
- 时间分辨率光谱观察反应性.
- 对溶剂同位素组成,缓冲度和pH依赖性的分析,以研究质子转移动力学.
主要成果:
- 在马库斯逆转区域内发生FnY356的光氧化,其重组能量 (λ) 约为1 eV.
- 在存在完整的PCET通路时,观察到增强电子合 (HDA).
- 证据表明α2子单元在β-Y356光氧化过程中促进质子转移 (PT),在紧密的接口内发生易于交换的位置.
结论:
- RNR通过降低重组能量 (λ) 和增加电子合 (HDA) 来控制电子转移.
- α2子单元在指导和促进RNR复合体内的质子转移方面发挥着至关重要的作用.
- 这项研究为DNA复制和修复所必需的核酸减少的复杂机制提供了新的见解.
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