title: S0-State model of the oxygen-evolving complex of photosystem II.
abstract: The S0 → 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 → S1 transition, where oxidation of a Mn center and deprotonation of a μ-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.
authors.affiliation: Department of Chemistry, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Rhitankar
authors.initials: R
authors.lastname: Pal
authors.forename: Christian F A
authors.initials: CF
authors.lastname: Negre
authors.forename: Leslie
authors.initials: L
authors.lastname: Vogt
authors.forename: Ravi
authors.initials: R
authors.lastname: Pokhrel
authors.forename: Mehmed Z
authors.initials: MZ
authors.lastname: Ertem
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
authors.forename: Victor S
authors.initials: VS
authors.lastname: Batista
mesh_terms: D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D008345:Manganese