title: Photosynthetic water oxidation: binding and activation of substrate waters for O-O bond formation.
abstract: Photosynthetic water oxidation occurs at the oxygen-evolving complex (OEC) of Photosystem II (PSII). The OEC, which contains a Mn4CaO5 inorganic cluster ligated by oxides, waters and amino-acid residues, cycles through five redox intermediates known as S(i) states (i = 0-4). The electronic and structural properties of the transient S4 intermediate that forms the O-O bond are not well understood. In order to gain insight into how water is activated for O-O bond formation in the S4 intermediate, we have performed a detailed analysis of S-state dependent substrate water binding kinetics taking into consideration data from Mn coordination complexes. This analysis supports a model in which the substrate waters are both bound as terminal ligands and react via a water-nucleophile attack mechanism.
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, United States. gary.brudvig@yale.edu.
authors.forename: David J
authors.initials: DJ
authors.lastname: Vinyard
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, United States. gary.brudvig@yale.edu.
authors.forename: Sahr
authors.initials: S
authors.lastname: Khan
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT, United States. gary.brudvig@yale.edu.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010788:Photosynthesis; D014867:Water / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D014867:Water; D008345:Manganese; D010100:Oxygen