Simulation of the isotropic EXAFS spectra for the S-2 and S-3 structures of the oxygen evolving complex in photosystem II

AuthorCount:3;
Most of the main features of water oxidation in photosystem II are now well understood, including the mechanism for O-O bond formation. For the intermediate S-2 and S-3 structures there is also nearly complete agreement between quantum chemical modeling and experiments. Given the present high degree of consensus for these structures, it is of high interest to go back to previous suggestions concerning what happens in the S-2-S-3 transition. Analyses of extended X-ray adsorption fine structure (EXAFS) experiments have indicated relatively large structural changes in this transition, with changes of distances sometimes larger than 0.3 angstrom and a change of topology. In contrast, our previous density functional theory (DFT)(B3LYP) calculations on a cluster model showed very small changes, less than 0.1 angstrom. It is here found that the DFT structures are also consistent with the EXAFS spectra for the S2 and S3 states within normal errors of DFT. The analysis suggests that there are severe problems in interpreting EXAFS spectra for these complicated systems.

Siegbahn, Per E. M.Stockholms universitet,Institutionen för organisk kemi(Swepub:su)ps (författare)
Ryde, Ulf (författare)
Stockholms universitetInstitutionen för organisk kemi (creator_code:org_t)

Ingår i:Proceedings of the National Academy of Sciences of the United States of America: Proceedings of the National Academy of Sciences112:13, s. 3979-39840027-84241091-6490

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