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AKB: Biologische Physik

AKB 4: Membranes: Phase Behavior and Dynamics

AKB 4.1: Talk

Monday, March 27, 2006, 12:00–12:15, ZEU 260

Dynamic simulations of lateral diffusion in fluctuating membranes — •Ellen Reister-Gottfried and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart

When regarding lateral diffusion it is important to remember, that the membrane is flexible and subject to thermal fluctuations. Therefore the Langevin (or Smolouchovski) equation governing the dynamics of a protein diffusing in the membrane becomes a function of the membrane shape. In our novel simulation algorithm we combine the simulation of the membrane dynamics with the simulation of the protein movement. The membrane dynamics follows from the membrane Hamiltonian and a hydrodynamic coupling of the membrane to the surrounding fluid. The movement of the inclusion is calculated by numerically integrating the appropriate Langevin equation, that uses the instantaneous membrane shape. This simulation method allows for studies on large length and time scales and is easily extendable to include various protein-membrane interactions or external potentials acting on the membrane. We use this scheme to calculate diffusion coefficients projected on a flat plane, because this is the quantity, that is typically measured in experiments. In previous work we analytically calculated the difference between the projected and the actual intramembrane diffusion coefficient in the limit that membrane fluctuations are faster than protein diffusion. These results are compared with results achieved with the new simulation method.