title: Calcium in the oxygen-evolving complex: structural and mechanistic role determined by X-ray spectroscopy.
abstract: This review describes the results from X-ray Absorption Spectroscopy studies that have contributed to an understanding of the role of Ca in the photosynthetic water-oxidation reaction. The results include the first Mn, Ca and Sr X-ray spectroscopy studies using Ca or Sr-substituted PS II samples that established the presence of a MnCa heteronuclear structure and its orientation, and the most recent Sr X-ray spectroscopy study using biosynthetically prepared Sr-containing PS II in the various S-states that provide important insights into the requirement for Ca in the mechanism of the Mn(4)Ca catalytic center.
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. VKYachandra@lbl.gov
authors.forename: Vittal K
authors.initials: VK
authors.lastname: Yachandra
authors.forename: Junko
authors.initials: J
authors.lastname: Yano
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000502:physiology*; D020134:Catalytic Domain; D010100:Oxygen / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy
chemical_list: D045332:Photosystem II Protein Complex; D010100:Oxygen; D002118:Calcium