Frankfurt 2006 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 60: Laserspektroskopie I
Q 60.2: Vortrag
Donnerstag, 16. März 2006, 11:25–11:40, HII
Investigation of PS II composition in Acaryochloris marina by picosecond fluorescence spectroscopy — •Franz-Josef Schmitt1, Christoph Theiss1, Hann-Jörg Eckert2 und Hans Joachim Eichler1 — 1Optisches Institut P 1-1, Technische Universität Berlin — 2Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin
Most oxygenic photosynthetic organisms contain mainly Chl a and Chl b. The cyanobacterium A.marina is the only known organism containing mainly Chl d and phycobiliproteins in the light harvesting antenna system. The Q-1mmy absorption band of Chl d is shifted towards longer wavelengths with respect to Chl a. This spectroscopic property raises important questions about the mechanism of excitation energy transfer between the antenna pigments. Especially the nature of the primary donor of Photosystem II (PS II) of A.marina is still a matter of discussion. At 77 K a long-lived 15 ns-fluorescence component was observed at 685 nm and ascribed to delayed Chl a-fluorescence occurring after charge recombination between the primary electron donor and the primary electron acceptor of PS II [1]. In this report it is shown that the spectrum of the 15 ns component is not typical for Chl a and was only observed upon excitation at 400 nm but not upon excitation at 632 and 654 nm. After photoinhibition such a fluorescence component appeared in the spectroscopic region of Chl d (725 nm). Based on this results it cannot be assigned to a delayed Chl a-fluorescence and therefore not used as an argument that the primary donor of PS II contains Chl a.
[1] M. Mimuro et al, FEBS Lett. 2004, 556, 95-98.