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BP: Fachverband Biologische Physik

BP 25: Membranes

BP 25.3: Vortrag

Freitag, 27. März 2009, 11:00–11:15, HÜL 186

Specific adhesion of membranes: the role of membrane fluctuations — •Ellen Reister, Ana-Sunčana Smith, and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany

We analyse adhesion of a membrane to a flat surface via receptor-ligand pairs both in equilibrium and during the adhesion process. The membrane is modeled with the Helfrich energy, while the ligands in the membrane may react with receptors attached to the substrate via springs. The corresponding reaction rate depends on the distance between membrane and substrate. The positions of the ligands in the membrane and the tethers attached to the substrate are kept fixed. For the two coupled dynamic processes in the system - membrane fluctuations and receptor-ligand reactions -- we derive equations of motion that are numerically integrated in our novel simulation scheme. To study the influence of thermal membrane shape fluctuations we compare results for a stiff membrane with simulation results. In equilibrium we find that fluctuations make the transition from a bound to an unbound membrane more continuous and that higher binding energies are necessary to maintain the same degree of adhesion. During the dynamic process of adhesion membrane fluctuations are found to increase the adhesion speed. Both in equilibrium and during adhesion observed spatial correlations between bonds indicate that the fluctuating membrane mediates an attractive force between neighboring bonds.