Darmstadt 2008 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 1: Biomoleküle

MO 1.5: Vortrag

Montag, 10. März 2008, 15:15–15:30, 3F

Comparison of the fluorescence kinetics of detergent-solubilized and membrane-reconstituted LH2 complexes — •Tobias Pflock¹, Manuela Dezi², Giovanni Venturoli², Richard J. Cogdell³, Jürgen Köhler¹, and Silke Oellerich¹ — ¹Experimentalphysik IV, Universität Bayreuth, D-95447 Bayreuth — ²Dept. of Biology, University of Bologna, Italy — ³GBRC, University of Glasgow, UK

Picosecond time-resolved fluorescence spectroscopy has been used in order to compare the fluorescence kinetics of detergent-solubilized and membrane-reconstituted light-harvesting 2 (LH2) complexes from the bacteria Rhodopseudomonas (Rps.) acidophila and Rhodobacter (Rb.) sphaeroides. LH2 complexes were reconstituted in phospholipid model membranes at different lipid:protein-ratios and all samples were studied exciting with a wide range of excitation densities. While the detergent-solubilized LH2 complexes from Rps. acidophila showed monoexponential decay kinetics (τ_f = 980 ps) for excitation densities of up to 3· 10¹³ photons/(pulse· cm²), the membrane-reconstituted LH2 complexes showed multiexponential kinetics even at low excitation densities and high lipid:protein-ratios. The latter finding indicates an efficient clustering of LH2 complexes in the phospholipid membranes. Similar results were obtained for the LH2 complexes from Rb. sphaeroides.