Possibility of the right-opened Mn-oxo intermediate (R-oxo(4444)) among all nine intermediates in the S3 state of the oxygen-evolving complex of photosystem II revealed by large-scale QM/MM calculations

• Published in: Chemical physics 2019-02, Vol.518, p.81-90
• Main Authors: Shoji, Mitsuo, Isobe, Hiroshi, Miyagawa, Koichi, Yamaguchi, Kizashi
• Format: Article
• Language: English
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2018.11.003

[Display omitted] •Nine S3 intermediates of the oxygen-evolving complex of photosystem II were investigated.•Full geometrical optimizations for the large-scale QM/MM models were performed.•Mn valence states and the CaMn4O6 structure were compared to the experimental results.•Right-opened Mn-oxo can be a candidate for the S3 intermediate state. Large-scale quantum mechanics/molecular mechanics (QM/MM) calculations were performed to elucidate the possible intermediates in the S3 state of the oxygen-evolving complex of photosystem II. We have investigated nine S3 candidates in the R-/L-opened Mn-hydroxide, Mn-oxo, Mn-peroxide and Mn-superoxide intermediate states, and their optimized CaMn4O6 structures and the Mn valence states were compared to the experimental results revealed by recent serial femtosecond crystallography (SFX) and X-ray emission spectroscopy (XES). By using the Jahn-Teller (JT) deformation formulae, the Mn4-O(5) and O(5)-O(6) distances were estimated from the Mn4-Mn3 distances. Among all the calculated S3 intermediates, not only the right-opened hydroxo intermediate (R-hydroxo), but also the right-opened Mn-oxo intermediate (R-oxo(4444)) were found to be plausible based on the calculated CaMn4O6 structure and the Mn valence state (4444).