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在自然的水氧化复合体的S₂到S₃过渡过程中,高自旋脱质中间体的分子识别

Thomas A Corry¹, Patrick J O'Malley¹

¹Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K.

Journal of the American Chemical Society

|May 21, 2020

概括

研究人员在S2到S3过渡期间确定了光系统2的氧化水复合体 (WOC) 中的关键中间体. 这一发现澄清了WOC的自旋状态和连体变化,对于理解光合作用中的水氧化是必不可少的.

科学领域:

生物化学
光合作用研究
有机生物化学

背景情况:

光系统2 (PS2) 含有氧化水复合体 (WOC),负责将水分解为氧,质子和电子.
了解WOC的机制,特别是S2到S3的转换,是人工光合作用和能量转换的关键.

研究的目的:

在WOC的S2到S3过渡中确定一个关键中间体的特定化学结构和旋转状态.
阐明联体变化的作用,以调节 WOC 在催化循环中的电子特性.

主要方法:

用破碎对称密度函数理论 (BS-DFT) 的计算来建模WOC.
使用海森伯格 - 迪拉克 - 范弗莱克 (HDvV) 旋转梯计算来确定旋转状态.
进行X波段电子磁共振 (EPR) 光谱分析以将计算结果与实验数据相关联.

主要成果:

在S2状态模型中,该研究确定了从S = 5/2旋转状态 (W1为水联体) 过渡到S = 7/2旋转状态 (W1为联体).
将g=4. 1的EPR信号分配到S=5/2状态,其中W1作为水联体.
在高pH下观察到的g = 4. 8/ 4. 9 EPR信号被分配到S = 7/ 2状态,其中W1作为氧联体.

结论:

用W1作为氧联体的S=7/2状态被提出为促进向S3状态的关键中间体.
这项工作为WOC机制提供了关键的见解,将电子结构,配体动力学和催化活性联系起来.

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