title: Amino acid residues involved in the coordination and assembly of the manganese cluster of photosystem II. Proton-coupled electron transport of the redox-active tyrosines and its relationship to water oxidation.
abstract: The combination of site-directed mutagenesis, isotopic labeling, new magnetic resonance techniques and optical spectroscopic methods have provided new insights into cofactor coordination and into the mechanism of electron transport and proton-coupled electron transport in photosystem II. Site-directed mutations in the D1 polypeptide of this photosystem have implicated a number of histidine and carboxylate residues in the coordination and assembly of the manganese cluster, responsible for photosynthetic water oxidation. Many of these are located in the carboxy-terminal region of this polypeptide close to the processing site involved in its maturation. This maturation is a required precondition for cluster assembly. Recent proposals for the mechanism of water oxidation have directly implicated redox-active tyrosine Y(Z) in this mechanism and have emphasized the importance of the coupling of proton and electron transfer in the reduction of Y(Z)(radical) by the Mn cluster. The interaction of both homologous redox-active tyrosines Y(Z) and Y(D) with their respective homologous proton acceptors is discussed in an effort to better understand the significance of such coupling.
authors: CR&D, Experimental Station, E.I. du Pont de Nemours and Co., Wilmington DE 19880-0173, USA. bruce.a.diner@usa.dupont.com
authors: B A
authors: BA
authors: Diner
mesh_terms: D020418:Algal Proteins; D000596:Amino Acids / Q000737:chemistry*; D001665:Binding Sites; D002268:Carboxypeptidases; D002734:Chlorophyll / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D010450:Endopeptidases / Q000737:chemistry; D045342:Light-Harvesting Protein Complexes; D008345:Manganese / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D043484:Proprotein Convertases; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D020418:Algal Proteins; D000596:Amino Acids; D045342:Light-Harvesting Protein Complexes; D009942:Organometallic Compounds; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011522:Protons; C066447:tyrosyl radical Y(D); C114979:tyrosyl radical YZ; D014867:Water; D002734:Chlorophyll; D014443:Tyrosine; D008345:Manganese; C025167:P-680; D002268:Carboxypeptidases; D010450:Endopeptidases; D043484:Proprotein Convertases; C073491:photosystem II, D1 polypeptide carboxy-terminal processing protease; D010100:Oxygen