Pulsed and parallel-polarization EPR characterization of the photosystem II oxygen-evolving complex.
Photosystem II uses visible light to drive the oxidation of water, resulting in bioactivated electrons and protons, with the production of molecular oxygen as a byproduct. This water-splitting reaction is carried out by a manganese cluster/tyrosine radial ensemble, the oxygen -evolving complex. Although conventional continuous-wave, perpendicular -polarization electron paramagnetic resonance (EPR) spectroscopy has significantly advanced our knowledge of the structure and function of the oxygen-evolving complex, significant additional information can be obtained with the application of additional EPR methodologies. Specifically, parallel-polarization EPR spectroscopy can be use to obtain highly resolved EPR spectra of integer spin Mn species, and pulsed EPR spectroscopy with electron spin echo-based sequences, such as electron spin echo envelope modulation and electron spin echo-electron nuclear double resonance, can be used to measure weak interactions obscured in continuous-wave spectroscopy by inhomogeneous broadening.
Department of Chemistry, University of California, Davis 95616, USA. rdbritt@ucdavis.edu
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D000458:Cyanobacteria / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D007700:Kinetics; D008345:Manganese / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism
D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D008345:Manganese; D013482:Superoxide Dismutase; D010100:Oxygen