title: Photosystem II single crystals studied by EPR spectroscopy at 94 GHz: the tyrosine radical Y(D)(*).
abstract: Electron paramagnetic resonance (EPR) spectroscopy at 94 GHz is used to study the dark-stable tyrosine radical Y(D)(*) in single crystals of photosystem II core complexes (cc) isolated from the thermophilic cyanobacterium Synechococcus elongatus. These complexes contain at least 17 subunits, including the water-oxidizing complex (WOC), and 32 chlorophyll a molecules/PS II; they are active in light-induced electron transfer and water oxidation. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with four PS II dimers per unit cell. High-frequency EPR is used for enhancing the sensitivity of experiments performed on small single crystals as well as for increasing the spectral resolution of the g tensor components and of the different crystal sites. Magnitude and orientation of the g tensor of Y(D)(*) and related information on several proton hyperfine tensors are deduced from analysis of angular-dependent EPR spectra. The precise orientation of tyrosine Y(D)(*) in PS II is obtained as a first step in the EPR characterization of paramagnetic species in these single crystals.
authors.affiliation: Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Technische Universität Berlin, Strasse des 17, Juni 135, D-10623 Berlin, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Hofbauer
authors.forename: A
authors.initials: A
authors.lastname: Zouni
authors.forename: R
authors.initials: R
authors.lastname: Bittl
authors.forename: J
authors.initials: J
authors.lastname: Kern
authors.forename: P
authors.initials: P
authors.lastname: Orth
authors.forename: F
authors.initials: F
authors.lastname: Lendzian
authors.forename: P
authors.initials: P
authors.lastname: Fromme
authors.forename: H T
authors.initials: HT
authors.lastname: Witt
authors.forename: W
authors.initials: W
authors.lastname: Lubitz
mesh_terms: D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D014443:Tyrosine
chemical_list: D005609:Free Radicals; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D014443:Tyrosine