X-ray spectroscopy of the Mn4Ca cluster in the water-oxidation complex of Photosystem II.
The water-oxidation complex of Photosystem II (PS II) contains a heteronuclear cluster of 4 Mn atoms and a Ca atom. Ligands to the metal cluster involve bridging O atoms, and O and N atoms from amino acid side-chains of the D1 polypeptide of PS II, with likely additional contributions from water and CP43. Although moderate resolution X-ray diffraction-based structures of PS II have been reported recently, and the location of the Mn4Ca cluster has been identified, the structures are not resolved at the atomic level. X-ray absorption (XAS), emission (XES), resonant inelastic X-ray scattering (RIXS) and extended X-ray absorption fine structure (EXAFS) provide independent and potentially highly accurate sources of structural and oxidation-state information. When combined with polarized X-ray studies of oriented membranes or single-crystals of PS II, a more detailed picture of the cluster and its disposition in PS II is obtained.
Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA. khsauer@lbl.gov
Kenneth
K
Sauer
Junko
J
Yano
Vittal K
VK
Yachandra
D017610:Calcium Compounds / Q000737:chemistry* / Q000378:metabolism; D017895:Manganese Compounds / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D013052:Spectrometry, X-Ray Emission; D014867:Water / Q000737:chemistry / Q000378:metabolism*
D017610:Calcium Compounds; D017895:Manganese Compounds; D045332:Photosystem II Protein Complex; D014867:Water