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序列女性秒结晶学是否描绘了氧化复合物的特定状态的催化中间体?

Maria Drosou¹, Gerard Comas-Vilà², Frank Neese¹

¹Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.

Journal of the American Chemical Society

|May 3, 2023

概括

使用X射线自由电子激光器 (XFEL) 的连续秒结晶学 (SFX) 揭示了氧化复合物 (OEC) 的结构模型. 然而,这些模型的几何数据与S2状态的预期氧化状态不完全一致.

科学领域:

生物化学和生物物理
结构生物学
光合作用研究

背景情况:

用X射线自由电子激光器 (XFEL) 进行的连续秒结晶学 (SFX) 已经产生了光系统II (PSII) 氧进化复合体 (OEC) 中间体的结构模型.
这些模型代表了OEC通过催化S状态循环中间体 (S1,S2,S3,S0) 的快速推进.
由于对光谱验证的氧化状态的几何参数和预期的协调化学之间的差异,这些模型的解释受到争议.

研究的目的:

在OEC中使用SFX-XFEL晶体数据批判性地评估S1 → S2过渡的结构和电子特性.
评估现有的1闪 (1F) 晶体模型与OEC预期的S2状态的一致性.
研究在双闪 (2F) 结构模型中确定氧化状态的可行性.

主要方法:

对OEC现有的1闪 (1F) SFX-XFEL晶体模型进行分析.
应用几何和电子结构标准,包括一种新的有效氧化状态方法.
结晶学数据与氧化状态和电子计数的协调化学预期的比较.

主要成果:

一闪 (1F) 模型与S2状态的等价性是可疑的.
在1F/S2模型中,的氧化状态和未配对的电子数量与纯S2状态或S1→S2过渡不完全一致.
在二闪 (2F) 模型中确定氧化状态几乎是不可能的.

结论:

在仅从晶体模型的字面解释中推断电子结构时,建议谨慎.
需要对结构和机制解释进行重新评估,特别是那些假设与特定OEC催化中间体完全相对应的解释.
当前的SFX-XFEL模型可能无法准确地表示OEC的独特S状态中间体.

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