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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.49: Poster

Donnerstag, 27. März 2003, 15:30–18:00, P1

Entropic Forces in Biological Systems — •Heiko Elsinger¹, Thomas Gisler¹, Paul Leiderer¹, Rainer Tharmann², Andreas Bausch², and Clemens Bechinger¹ — ¹Universität Konstanz, Fachbereich Physik, 78467 Konstanz — ²Technische Universität München, Lehrstuhl für Biophysik, 85747 Garching

In colloid-polymer mixtures free volume effects are well known to lead to entropic interactions which are responsible for rich phase diagrams in such situations. While the understanding of entropic forces in model systems, e.g. colloidal suspensions, has considerably put forward during the last years, only little is known about the importance of those forces in biological systems where entropic forces are also assumed to play a major role. We investigate by means of surface plasmon spectroscopy and dynamic light scattering experiments the bundle formation of actin filaments in the presence of uncharged polymer coils of polyethylene glycol (PEG). Our results demonstrate that addition of PEG enhances the formation of acting bundles which is interpreted in terms of entropic forces. Because cytoplasmic proteins might have a similar effect as PEG, the actin filaments may form bundles in the cytoplasmic matrix more readily than expected.