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Biochemistry. 2011 Jul 26;50(29):6308-11. doi: 10.1021/bi200681q. Epub 2011 Jun 27.

S1-state model of the O2-evolving complex of photosystem II.

Author information

1
Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA. sandra.luber@yale.edu

Abstract

We introduce a quantum mechanics/molecular mechanics model of the oxygen-evolving complex of photosystem II in the S(1) Mn(4)(IV,III,IV,III) state, where Ca(2+) is bridged to manganese centers by the carboxylate moieties of D170 and A344 on the basis of the new X-ray diffraction (XRD) model recently reported at 1.9 Å resolution. The model is also consistent with high-resolution spectroscopic data, including polarized extended X-ray absorption fine structure data of oriented single crystals. Our results provide refined intermetallic distances within the Mn cluster and suggest that the XRD model most likely corresponds to a mixture of oxidation states, including species more reduced than those observed in the catalytic cycle of water splitting.

PMID:
21678908
PMCID:
PMC3139771
DOI:
10.1021/bi200681q
[Indexed for MEDLINE]
Free PMC Article

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