INFLUENCE OF CHANGES IN THE PHOTON PROTECTIVE ENERGY DISSIPATION ON RED LIGHT-INDUCED DETRAPPING OF THE THERMOLUMINESCENCE Z-BAND |
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| Authors: | Christoph Hagen Andrew A Pascal Peter Horton Yorinao Inoue |
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| Institution: | Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Hirosawa2–1, Wako, Saitama351–01, Japan;Institute of General Botany, Friedrich Schiller University Jena, Am Planetarium 1, D-07743 Jena, Germany;Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, P.O. Box 594, Western Bank, Sheffield S10 2UH, UK |
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| Abstract: | -Thermoluminescence emission at 110 K (Z-band) was markedly diminished when thylakoid membranes were exposed to red light during or after Z-band charging with blue light. Analysis of this phenomenon showed that deactivation of Z-band-emitting chlorophyll species occurred preferentially on the low temperature side of the glow curve, and red light of670–680 nm was most efficient in the deactivation. In order to test our hypothesis that this detrapping is related to local heating effects caused by dissipation of absorbed energy, we measured thermoluminescence glow curves and Z-band emission spectra from spinach leaf discs and thylakoid membranes during induction of nonphotochemical chlorophyll fluorescence quenching. Pretreatment of the plant material was designed to achieve different levels of (1) de-epoxidized xanthophylls in the photosynthetic apparatus and (2) the proton concentration in the thylakoid lumen. In comparison, measurements were performed in aggregated and trimeric light-harvesting pigment-protein complexes of photosystem II. We observed on all three levels of organization that a higher capacity of excitation energy dissipation was accompanied by a stronger red light-induced detrapping of Z-band thermoluminescence. |
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