Elsevier

Journal of Energy Chemistry

Volume 57, June 2021, Pages 436-442
Journal of Energy Chemistry

Necessity of structural rearrangements for Osingle bondO bond formation between O5 and W2 in photosystem II

https://doi.org/10.1016/j.jechem.2020.09.008Get rights and content
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Abstract

Numerous aspects of the water oxidation mechanism in photosystem II have not been fully elucidated, especially the Osingle bondO bond formation pathway. However, a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates. In this work, we studied Osingle bondO bond formation between O5 and W2 based on the native Mn4Ca cluster by density functional calculations. Structural rearrangements before the formation of the S4 state were found as a prerequisite for Osingle bondO bond formation between O5 and W2, regardless if the suggested pathways involving the typical Mn1(IV)-Oradical dot species or the recently proposed Mn4(VII)(O)2 species. Possible alternatives for the S2 → S3 and S3 → S4 transitions accounting for such required rearrangements are discussed. These findings reflect that the structural flexibility of the Mn4Ca cluster is essential to allow structural rearrangements during the catalytic cycle.

Graphical abstract

Osingle bondO bond formation between O5 and W2 in the non-rearranged oxygen-evolving complex has quite high barriers, and thus structural rearrangement during the catalytic cycle is necessary to facilitate their coupling.

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Keywords

Density functional theory
Oxygen-evolving complex
Substrate water
Osingle bondO bond formation
Structural rearrangement

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These authors contributed equally to this work.