Accessibility of tyrosine Y(.)(Z) to exogenous reductants and Mn(2+) in various Photosystem II preparations.
The reduction of tyrosine Y(.)(Z) by benzidine and exogenous Mn(2+) was studied by kinetic EPR experiments in various Photosystem II (PSII) preparations. Using lanthanide treated PSII membranes it was demonstrated that neither the extrinsic polypeptides (17, 23 and 33 kDa) nor the Mn complex block the accessibility of Y(.)(Z) to exogenous reductants, such as benzidine. In addition, it was shown that in the presence of the native Mn complex exogenous Mn(2+) does not reduce Y(.)(Z).
Department of Chemistry, University of Crete, PO Box 1470, 71409 Heraklion, Crete, Greece.
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Ghanotakis
D001560:Benzidines / Q000494:pharmacology; D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones; D007700:Kinetics; D008345:Manganese / Q000737:chemistry* / Q000494:pharmacology; D008674:Metals, Rare Earth; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D019163:Reducing Agents / Q000737:chemistry* / Q000494:pharmacology; D014443:Tyrosine / Q000737:chemistry*
D001560:Benzidines; D006873:Hydroquinones; D008674:Metals, Rare Earth; D010455:Peptides; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D019163:Reducing Agents; C029876:benzidine; D014443:Tyrosine; D008345:Manganese; C031927:hydroquinone