title: Evidence for a direct manganese-oxygen ligand in water binding to the S2 state of the photosynthetic water oxidation complex.
abstract: The interaction of water with the water oxidizing Mn complex of photosystem II has been investigated using electron spin-echo envelope modulation spectroscopy in the presence of H(2)(17)O. The spectra show interaction of the (17)O with the preparation in the S(2) state induced by 200 K illumination. The modulation is observed only in the center of the multiline spectrum. The inferred hyperfine coupling terms are compatible with water (not hydroxyl) oxygen bound to a particular quasi-axial Mn(III) center in a coupled Mn cluster.
authors.affiliation: Department of Biology, University College London, UK. mcw.evans@ucl.ac.uk
authors.forename: M C W
authors.initials: MC
authors.lastname: Evans
authors.forename: J H A
authors.initials: JH
authors.lastname: Nugent
authors.forename: R J
authors.initials: RJ
authors.lastname: Ball
authors.forename: I
authors.initials: I
authors.lastname: Muhiuddin
authors.forename: R J
authors.initials: RJ
authors.lastname: Pace
mesh_terms: D000222:Adaptation, Physiological; D001665:Binding Sites; D003624:Darkness; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005583:Fourier Analysis; D005615:Freezing; D008024:Ligands; D008345:Manganese / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010103:Oxygen Isotopes / Q000737:chemistry; D018532:Pisum sativum; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D008024:Ligands; D010103:Oxygen Isotopes; D045332:Photosystem II Protein Complex; D014867:Water; D008345:Manganese; D010100:Oxygen