Pheophytin-mediated energy storage of photosystem II particles detected by photoacoustic spectroscopy |
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Authors: | M. Fragata R. Popovic E. L. Camm R. M. Leblanc |
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Affiliation: | (1) Centre de recherche en photobiophysique, Université du Québec à Trois-Rivières, G9A 5H7 Trois-Rivières, Québec, Canada;(2) Present address: Botany Department, University of British Columbia, G6T 2B1 Vancouver, BC, Canada |
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Abstract: | The photoacoustic (PA) characteristics (energy storage and heat dissipation) of photosystem II (PSII) core-enriched particles from barley were studied (i) in conditions where there was electron flow, i.e., in the presence of a combination of the electron acceptor K3 Fe (CN)6, referred to as FeCN, and the electron donor diphenylcarbazide (DPC), and (ii) in conditions where electron flow was suppressed, i.e., in the absence of FeCN and DPC. The experimental data show that a decrease of heat dissipation with a minimum at 540 nm can be interpreted as energy storage resulting from the presence of pheophytin (Pheo) in the PSII particles. On account of the capability of the PA method to measure the energy absorbed by the chromophores which is converted to heat, it is suggested that the PA detection of Pheo present in the PSII complex will permit to clarify the function of processes involving non-radiative relaxation of excited states in P680-Pheo-QA interactions.Abbreviations -Car -Carotene - Chl Chlorophyll - DPC Diphenylcarbazide - EPR Electron Paramagnetic Resonance - FeCN potassium ferricyanide - HEPES N-2-hydroxyethylenepiperazine-N-2-ethanesulfonate - P680 reaction center of PSII - PA Photoacoustic - Pheo pheophytin - PSI photosystem I - PSII photosystem II - QA primary electron acceptor of PSII |
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Keywords: | pheophytin photosystem II PSII particles P680-Pheo energy storage photoacoustic spectroscopy |
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