Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 26: Biological systems II

CPP 26.4: Talk

Tuesday, March 8, 2005, 16:00–16:15, TU C230

Chromophore-matrix interaction in biological macromolecules — •J. Baier, M. Richter, C. Hofmann, S. Oellerich, and J. Köhler — Experimental Physics IV, University of Bayreuth

The spectral properties of multichromophoric systems are strongly affected by interactions between the individual chromophores as well as interactions between the chromophores and their host. An interesting macromolecular system for studying both types of interactions are
photosynthetic pigment-protein complexes like the bacterial light-harvesting 2 (LH 2) complex of purple bacteria where Bacteriochlorophyll a (BChl a) pigments are embedded in a protein matrix. Both, intramolecular motions and fluctuations of the matrix lead to changes in the chromophore-protein interaction and influence the properties of the optical transitions.

We performed a statistical analysis of spectral diffusion and spectral jumps of absorptions from individual BChl a molecules based on long series of fluorescence-excitation spectra of single LH 2 complexes. The results provide a detailed picture about the dynamics of the coupling between the chromophore and the matrix, i.e. about changes in the local environment of an individual chromophore.