Photosynthetic water oxidation: Binding and activation of substrate waters for O-O bond formation

David J. Vinyard, Sahr Khan, Gary W Brudvig

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37 Citations (Scopus)


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 Si 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.

Original languageEnglish
Pages (from-to)37-50
Number of pages14
JournalFaraday Discussions
Publication statusPublished - 2015


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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