title: Photosynthesis. Electronic structure of the oxygen-evolving complex in photosystem II prior to O-O bond formation.
abstract: The photosynthetic protein complex photosystem II oxidizes water to molecular oxygen at an embedded tetramanganese-calcium cluster. Resolving the geometric and electronic structure of this cluster in its highest metastable catalytic state (designated S3) is a prerequisite for understanding the mechanism of O-O bond formation. Here, multifrequency, multidimensional magnetic resonance spectroscopy reveals that all four manganese ions of the catalyst are structurally and electronically similar immediately before the final oxygen evolution step; they all exhibit a 4+ formal oxidation state and octahedral local geometry. Only one structural model derived from quantum chemical modeling is consistent with all magnetic resonance data; its formation requires the binding of an additional water molecule. O-O bond formation would then proceed by the coupling of two proximal manganese-bound oxygens in the transition state of the cofactor.
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany. nicholas.cox@cec.mpg.de wolfgang.lubitz@cec.mpg.de.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Cox
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Retegan
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Neese
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Pantazis
authors.affiliation: Institut de Biologie et de Technologies de Saclay, CNRS UMR 8221, Commissariat à l'Énergie Atomique (CEA) Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Boussac
authors.affiliation: Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany. nicholas.cox@cec.mpg.de wolfgang.lubitz@cec.mpg.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lubitz
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D055598:Chemical Phenomena; D000458:Cyanobacteria / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D009682:Magnetic Resonance Spectroscopy; D008345:Manganese / Q000737:chemistry; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D014867:Water; D008345:Manganese; D010100:Oxygen