Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 31: Posters: Membranes and Vesicles

BP 31.15: Poster

Donnerstag, 25. März 2010, 17:15–20:00, Poster B1

The role of diffusion on specific adhesion — •Timo Bihr, Ellen Reister, and Udo Seifert — Uni Stuttgart, II. Institute for Theoretical Physics

We analyse the adhesion of a flexible membrane to a flat substrate. Between the substrate and the membrane acts a confining potential in addition to reactions between receptors and ligands. The ligands in the membrane diffuse freely while the positions of the receptors in the substrate are kept fixed. The backbone of the receptor is modelled as a spring. The membrane fluctuations are described by a Langevin-Equation, which is numerically integrated in our simulation, the diffusion of the ligands is simulated by a simple random walk, and the reaction rate between ligands and receptors depends on the binding energy and the distance between receptor and ligand.

In equilibrium we find that higher binding energies are required to sustain adhesion than in models with fixed ligand positions because of a higher entropy contribution to the free energy. The simulations were run for different ligand concentrations, diffusion constants, reaction rates, binding energies and strain energies of the receptor. The adhesion process depends crucially on the diffusion constant of the ligands. For high diffusion constants bond clusters develop while for low diffusion constants bonds form independently from each other. This effect also has an influence on the average height of the membrane because evenly spread bonds pull the membrane closer to the substrate than bonds that are concentrated in one region.