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MO: Fachverband Molekülphysik
MO 16: Biomoleküle
MO 16.10: Poster
Tuesday, March 11, 2008, 14:00–19:00, Poster C1
The Interplay between Symmetry and Electronic Structure of Pigment-Protein Complexes from Purple Bacteria — •Ralf Kunz1, Martin Richter1, Silke Oellerich1, Jürgen Baier1, Thomas Prem1, Francesco Francia2, Giovanni Venturoli2, Dieter Oesterhelt3, June Southall4, Richard Cogdell4 und Jürgen Köhler1 — 1Experimentalphysik IV, Universität Bayreuth — 2University of Bologna — 3MPI für Biochemie, Martinsried — 4University of Glasgow
A recent rather low resolution X-ray crystal structure of the RC-LH1 core complex from the photosynthetic purple bacterium Rps. palustris showed the presence of a physical gap in the LH1 ring. The presence of such a gap, though functionally critical for the cyclic electron transport in the photosynthetic process, has become very controversial. We have now applied single-molecule spectroscopy to the RC-LH1 complexes of the purple bacteria Rps. palustris and Rb. sphaeroides (pufX- strain) to demonstrate that there is such a gap in the LH1 ring structure. More than 80% of the complexes from Rb. sphaeroides only show broad absorption bands, whereas all of the measurable complexes from Rps. palustris also have a narrow line at the low-energy end of their spectrum. We describe how the presence of this narrow feature indicates the presence of a gap in the electronic structure of the LH1 from Rps. palustris, which provides strong support for the physical gap that was previously modelled in its X-ray crystal structure.