Structural Dynamics of the Oxygen Evolving Complex of Photosystem II in Water-Splitting Action,Journal of the American Chemical Society

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Structural Dynamics of the Oxygen Evolving Complex of Photosystem II in Water-Splitting Action
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-04-12 , DOI: 10.1021/jacs.8b02620
Andrew J. Wilson ₁ , Prashant K. Jain _{1,

2,

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Affiliation

Oxygenic photosynthesis in nature occurs via water splitting catalyzed by the oxygen-evolving complex (OEC) of photosystem II. To split water, the OEC cycles through a sequence of oxidation states (S i, i = 0-4), the structural mechanism of which is not fully understood under physiological conditions. We monitored the OEC in visible-light-driven water-splitting action by using in situ, aqueous-environment surface-enhanced Raman scattering (SERS). In the unexplored low-frequency region of SERS, we found dynamic vibrational signatures of water binding and splitting. Specific snapshots in the dynamic SERS correspond to intermediate states in the catalytic cycle, as determined by density functional theory and isotopologue comparisons. We assign the previously ambiguous protonation configuration of the S0-S3 states and propose a structural mechanism of the OEC's catalytic cycle. The findings address unresolved questions about photosynthetic water splitting and introduce spatially resolved, low-frequency SERS as a chemically sensitive tool for interrogating homogeneous catalysis in operando.

中文翻译：

光系统II在水分解作用中析氧复合物的结构动力学

自然界中的含氧光合作用是通过光系统 II 的析氧复合物 (OEC) 催化的水分解发生的。为了分解水，OEC 在一系列氧化态 (Si, i = 0-4) 中循环，其结构机制在生理条件下尚不完全清楚。我们通过使用原位、水环境表面增强拉曼散射 (SERS) 监测可见光驱动的水分解作用中的 OEC。在 SERS 未开发的低频区域，我们发现了水结合和分裂的动态振动特征。动态 SERS 中的特定快照对应于催化循环中的中间状态，由密度泛函理论和同位素体比较确定。我们分配了先前模糊的 S0-S3 状态的质子化构型，并提出了 OEC 催化循环的结构机制。这些发现解决了关于光合水分解的未解决问题，并引入了空间分辨的低频 SERS 作为一种化学敏感工具，用于询问操作中的均相催化。

更新日期：2018-04-12

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