Structure-based mechanism of photosynthetic water oxidation

James P. McEvoy, Gary W. Brudvig

Research output: Contribution to journalArticlepeer-review

180 Citations (Scopus)

Abstract

The recently-published 3.5 Å resolution X-ray crystal structure of a cyanobacterial photosystem II (PDB entry 1S5L) provides a detailed architecture of the oxygen-evolving complex (OEC) and the surrounding amino-acids [K. N. Ferreira, T. M. Iverson, K. Maghlaoui, J. Barber and S. Iwata, Science, 2004, 203, 1831-1838]. The revealed geometry of the OEC lends weight to certain hypothesized mechanisms for water-splitting, including the one propounded by this group, in which a calcium-bound water acts as a nucleophile to attack the oxygen of a MnV=O group in the crucial O-O bond-forming step [J. S. Vrettos, J. Limburg and G. W. Brudvig, Biochim. Biophys. Acta, 2001, 1503, 229-245]. Here we re-examine this mechanism in the light of the new crystallographic information and make detailed suggestions concerning the mechanistic functions (especially the redox and proton-transfer roles) of calcium, chloride and certain amino-acid residues in and around the OEC. In particular, we propose an important role for an arginine residue, CP43-Arg357, in abstracting protons from a substrate water molecule during the water-splitting reaction.

Original languageEnglish
Pages (from-to)4754-4763
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume6
Issue number20
DOIs
Publication statusPublished - Oct 21 2004

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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