Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 10: Posters 2: Biomolecules, Energy Transfer, Clusters, Quantum Chemistry, Molecular Dynamics and Chirality
MO 10.3: Poster
Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais
Single-Molecule Fluorescence-Excitation Spectroscopy on LH2 Complexes from Allochromatium Vinosum — •Alexander Löhner1, Nichola Picken2, Richard Cogdell2, and Jürgen Köhler1 — 1Experimental Physics IV, University of Bayreuth, Germany — 2Institute of Molecular, Cell & Systems Biology College of Medical Veterinary and Life Sciences, University of Glasgow, United Kingdom
The absorption spectrum of the high-light peripheral light-harvesting complex (LH2 complex) from the photosynthetic purple bacterium Allochromatium vinosum features two strong absorptions around 800 nm and 850 nm. In contrast to LH2 complexes from other species for the high-light LH2 complex from Alc. Vinosum the intruiging feature is that the B800 band is split into two components.
Fluorescence-excitation spectra of the B800 band from 71 single LH2 complexes have been registered. From that spectra it was possible to calculate the intra- and intercomplex spectral heterogeneity, and to extract the relative intensity and the homogeneous linewidth of the B800 absorptions. From this analysis and from the sum of the performed measurements we can rule out that the split of the B800 band comes from different types of LH2 complexes.
From comparison with computer simulations, we find the best agreement between simulation and experiment for a ring-like oligomer of 12 repeat units. The splitting of the B800 band can be reproduced if both an excitonic coupling between dimers of B800 molecules and their interaction with the B850 manifold is taken into account.