Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 23: Photo-Biophysics

AKB 23.3: Vortrag

Donnerstag, 30. März 2006, 16:45–17:00, ZEU 255

Single Molecule Spectroscopy of Light Harvesting Complexes — •Sebastian Mackowski, Stephan Wörmke, Christoph Jung, Andreas Zumbusch, Moritz Ehrl, and Christoph Bräuchle — Department Chemie, Ludwig-Maximilians Universität München, Butenandtstrasse 11, 81377 München, Germany

Light harvesting complexes are ideal candidates for studying the interactions between proteins and chromophores. One of the least known is peridinin-chlorophyll-protein (PCP) complex - a photosynthetic molecule composed of a barrel of hydrophobic protein, which shields two subunits each comprising of a single chlorophyll molecule dressed by four peridinin molecules, which are responsible for the light harvesting in the blue-green spectral range. Here we report on single molecule spectroscopy measurements of different types of light harvesting molecules. The experiments carried out at room temperature show that the wild type PCP complexes are quite unstable and they bleach out within several seconds. On the other hand, in order to observe ultranarrow zero-phonon-line emission of this complex at cryogenic temperatures we combined the recently developed vibronic excitation scheme with a solid immersion lens. In this way, the significant increase of the effective numerical aperture of collection optics enables us to monitor time- and energy scales of spectral jumps characteristic for single chromophore fluorescence. Detailed analysis of these spectral fluctuations should provide unique information about the interaction between the protein and the chlorophyll, and should shed light onto the energy landscape of this protein complex.