Darmstadt 2008 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 16: Biomoleküle
MO 16.2: Poster
Dienstag, 11. März 2008, 14:00–19:00, Poster C1
Single-molecule spectroscopy on low-light adapted light-harvesting 2 complexes of Rhodopseudomonas palustris — •Paul Böhm1, Tatas Brotosudarmo2, Silke Oellerich1, Richard Cogdell2, and Jürgen Köhler1 — 1Experimental Physics IV and Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth — 2Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Biomedical Research Building, University of Glasgow
Low temperature (1.4 K) single-molecule fluorescence-excitation spectra have been recorded for a novel low-light (LL) adapted light-harvesting 2 (LH2) complex from Rhodopseudomonas palustris. For bulk samples the main spectroscopic feature of this complex in the near infrared is a ratio of 2.9 between the absorption maxima at 800 nm and 850 nm. All studied individual complexes feature 2-3 broad absorption bands in the 840-870 nm spectral region revealing a characteristic polarization dependence. In the 800 nm region the spectra of the individual complexes show several narrow absorption lines which vary from complex to complex both with respect to the number of lines and spectral positions. These measurements may contribute to the elucidation of the electronic structure of this novel light-harvesting complex, as to the narrow lines in the 800 nm region could indicate localized excitations on one or a few B800 bacteriochlorophyll a molecules, whereas the broad bands in the 850 nm region may suggest that the excitations are delocalized over a large number of B850 bacteriochlorophyll a molecules.