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AKB: Biologische Physik

AKB 200: Poster Session II

AKB 200.71: Poster

Dienstag, 8. März 2005, 17:00–19:00, Poster TU C

Single Molecule Anisotropy Measurements in Lipid Bilayers — •Jakob C. Schweizer, Zdeněk Petrášek, and Petra Schwille — Biotechnologisches Zentrum der TU Dresden; Institut für Biophysik; Tatzberg 47-51; 01307 Dresden; Germany

Fluorescence widefield microscopy was combined with polarization optics in order to study the fluorescence polarization of single biomolecules. The fluorescence emission was split by a wollaston prism, providing spatially displaced images for the parallel and perpendicular polarization components, respectively. From these images, fluorescence anisotropy values were calculated.

A common cause for fluorescence depolarization, among others, is rotational diffusion. Initial measurements were performed in which orientation and rotational diffusion of flourescent dyes in supported lipid bilayers in different membrane phases were investigated. In these systems, the orientation of transition dipoles of the used dyes was shown to be restricted to two dimensions. The Perrin equation for such a two-dimensional system was deduced. Fluorescence anisotropy values from ensemble measurements and single molecule-measurements were compared. The investigation of rotational diffusion on the single molecule level is expected to yield a deeper insight into the structure and dynamics of biological systems.