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).
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry