两个低屏障键的相互作用在长距离的质子合电子转移中,用于氧化水的氧化
Keisuke Saito1,2, Shunya Nishio1, Hiroshi Ishikita1,2
1Department of Applied Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan.
PNAS nexus
|December 22, 2023
概括
这项研究揭示了氧化TyrZ如何通过键网络驱动光系统II中的质子转移. 这种机制解释了TyrZ氧化和质子化事件之间的长距离相互作用.
科学领域:
- 生物物理学的生物物理.
- 光合作用研究研究光合作用.
- 量子化学是一种量子化学.
背景情况:
- 氨酸D (TyrZ) 在光系II中对电子转移至关重要,它与D1-His190.0形成低屏障H键.
- TyrZ氧化到TyrZ-O•接受Mn4CaO5集群的电子,推进催化循环 (S0-S3状态).
研究的目的:
- 研究S2到S3过渡期间由TyrZ-O•驱动的质子合电子转移的机制.
- 阐明联网在光系统II内的长距离相互作用中介作用.
主要方法:
- 采用量子力学/分子力学 (QM/MM) 方法.
- 在光系统II中模拟了S2到S3的过渡.
主要成果:
- TyrZ-O•形成导致Ca2+位点的水分子 (W4) 重定向,向D1-Glu189.9捐赠键.
- 这种相互作用触发了从W1到Mn4的质子释放,通过低屏障H键激发了D1-Asp61的质子.
- 一个扩展的Grotthuss类网络涉及TyrZ,Mn4CaO5和W1-Asp61系统,促进了质子转移.
结论:
- 质子转移机制依赖于两个低屏障H键的相互作用和一个扩展的格罗图斯式网络.
- 这种网络,而不是直接的静电学,解释了观察到的TyrZ-O•形成和D1-Asp61质子化之间的长距离相互作用.
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