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

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

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Models, Molecular*
  • Oxygen / metabolism*
  • Photosystem II Protein Complex / chemistry*
  • Protein Conformation
  • Quantum Theory
  • Spectroscopy, Fourier Transform Infrared
  • X-Ray Absorption Spectroscopy

Substances

  • Photosystem II Protein Complex
  • Oxygen