Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 4: Membranes: Phase Behavior and Dynamics

AKB 4.4: Talk

Monday, March 27, 2006, 12:45–13:00, ZEU 260

Ordered domains control membrane diffusion in model membranes — •Carsten Selle, Florian Rückerl, and Josef Käs — University of Leipzig, Insitute for Experimental Physics I, Soft Matter Physics, Linnestr 5, 04103 Leipzig, Germany

We investigate the diffusion properties of biological membrane components by a Single-Particle-Tracking (SPT) technique employing monolayers at the air/water interface as two-dimensional membrane mimetics. Protein diffusion within inhomogeneous membranes was mimicked by motion of surface-charged fluorescent polystyrene beads in monolayers where two differently ordered phases coexist. Associated to ordered liquid-condensed (LC) domains, dimensionally reduced motion of the model proteins in the liquid-expanded (LE) phase was observed. We assume that dipole-dipole interactions between the diffusing beads and LC domains give rise to an attractive potential resulting in a strikingly modified bead diffusion in the LC domain neighborhood. This view point is supported by suitable Monte-Carlo simulations. The simulations demonstrate that model protein diffusion can be strongly affected by both potential depth and also by the domain size. It seems conceivable that living cells could make use of diffusion control accomplished by similar mechanisms in order to enhance kinetics of bimolecular enzyme reactions occuring in the membrane. In recent experiments performed in our lab, giant unilamellar vesicles interacting with fluorescent polystyrene beads have been employed to study the behavior of model proteins at curved sufaces. First results are presented.