title: S1-state model of the O2-evolving complex of photosystem II.
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.
authors.affiliation: Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA. sandra.luber@yale.edu
authors.forename: Sandra
authors.initials: S
authors.lastname: Luber
authors.forename: Ivan
authors.initials: I
authors.lastname: Rivalta
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Umena
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawakami
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kamiya
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
authors.forename: Victor S
authors.initials: VS
authors.lastname: Batista
mesh_terms: D008958:Models, Molecular; D010100:Oxygen / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D011487:Protein Conformation; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D056928:X-Ray Absorption Spectroscopy
chemical_list: D045332:Photosystem II Protein Complex; D010100:Oxygen