Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 27: Membrane Morphology and Adhesion

BP 27.3: Vortrag

Freitag, 29. Februar 2008, 11:00–11:15, C 243

Adhesion dynamics of fluctuating membranes — •Ellen Reister-Gottfried and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany

We study a system consisting of a fluctuating membrane close to a flat substrate that may adhere to the substrate via receptor-ligand bonds that we model as springs with a certain stiffness. We keep the position of the ligands on the substrate fixed and assume such a high abundance of receptors in the membrane that lateral diffusion has no influence on the adhesion process. While the energy of the membrane and the bonds combined with an appropriate Onsager coefficient determine the equation of motion for the membrane, the binding and unbinding of receptor-ligand pairs is expressed with Kramers rates, that depend on the local distance between membrane and substrate. Applying stochastic simulations we study the adhesion process of an initially unbound membrane as a function of binding energy, spring stiffness, and bending rigidity of the membrane. We analyse two limiting cases: the average distance between the membrane and substrate is i) either fixed or ii) variable allowing center of mass movement of the membrane. For i) we find that membrane fluctuations together with the height dependent reaction rates increase the number of bonds compared to a flat membrane. Furthermore, strong spatial correlations between the bonds are observed. In situation ii) equilibrium calculations for a flat membrane reveal a bimodal binding probability for certain binding energies. Our simulations show that membrane fluctuations break this bimodality. Additionally, spatial correlations are reduced compared to i).