Dresden 2009 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 26: Photobiophysics
BP 26.3: Vortrag
Freitag, 27. März 2009, 11:30–11:45, ZEU 260
Analysis of pigment-protein-complexes by hole burning- and time resolved fluorescence spectroscopy — •Elmar Hassan Hubrich1, Franz-Josef Schmitt1, Jörg Pieper2, Hans Joachim Eichler1, and Gernot Renger2 — 1Institut für Optik und Atomare Physik — 2Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin
The water-soluble chlorophyll-binding protein (WSCP) found in plants is primarily expressed under stress conditions (drought, heat). The precise function is still not clearified. In contrast to other photosynthetic pigment-protein complexes WSCP binds a maximum number of one molecule chlorophyll (Chl a or b) per subunit and does not contain carotenoids. WSCP forms tetrameric complexes, with two strongly excitonically coupled chlorophylls in an “open sandwich” geometry. Chl bound to WSCP shows a drastically reduced formation of reactive singlet oxygen in comparison to Chl in solution. WSCP is an excellent minimal model system to investigate pigment-pigment and pigment-protein interactions. We applied the complementary techniques of picosecond fluorescence spectroscopy (time- and wavelength-correlated single photon counting) and hole-burning spectroscopy. A fluorescence rise kinetics was found with a characteristic lifetime of 80 ps at 10 K, noticeably shorter lifetime and markedly reduced amplitude at 160 K and a time constant below the detection limit at higher temperatures. Hole burning and temperature dependent absorption spectroscopy were used to determine the spectral positions of the exciton states and to characterize their coupling to protein vibrations.