S0-State Model of the Oxygen-Evolving Complex of Photosystem II

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• 作者：Rhitankar Pal ; Christian F. A. Negre ; Leslie Vogt ; Ravi Pokhrel ; Mehmed Z. Ertem ; Gary W. Brudvig ; Victor S. Batista
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：November 5, 2013
• 年：2013
• 卷：52
• 期：44
• 页码：7703-7706
• 全文大小：300K
• 年卷期：v.52,no.44(November 5, 2013)
• ISSN：1520-4995

文摘

The S₀ 鈫?S₁ transition of the oxygen-evolving complex (OEC) of photosystem II is one of the least understood steps in the Kok cycle of water splitting. We introduce a quantum mechanics/molecular mechanics (QM/MM) model of the S₀ state that is consistent with extended X-ray absorption fine structure spectroscopy and X-ray diffraction data. In conjunction with the QM/MM model of the S₁ state, we address the proton-coupled electron-transfer (PCET) process that occurs during the S₀ 鈫?S₁ transition, where oxidation of a Mn center and deprotonation of a 渭-oxo bridge lead to a significant rearrangement in the OEC. A hydrogen bonding network, linking the D1-D61 residue to a Mn-bound water molecule, is proposed to facilitate the PCET mechanism.