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BP: Fachverband Biologische Physik

BP 31: Posters: Membranes and Vesicles

BP 31.7: Poster

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

Monte Carlo simulation of two-component membranes: Phase separation dynamics and anomalous diffusion — •Jens Ehrig, Eugene P. Petrov, and Petra Schwille — Biophysics, BIOTEC, TU Dresden, Tatzberg 47/49, 01307 Dresden

Anomalous subdiffusion is an intriguing phenomenon frequently observed in cell membranes, e.g. in SPT, FCS, and FRAP experiments. It is usually ascribed to the presence of membrane heterogeneities with dimensions below the optical resolution limit. In order to understand how the sub-micrometer-scale phase separation in the cell membrane can affect the lipid diffusion and manifest itself experimentally, we carry out dynamic Monte Carlo simulations of a two-component lipid membrane (DMPC/DSPC) with the size on the micrometer scale over time intervals of order of a second. Our model correctly reproduces the thermodynamic properties, as well as the phase diagram of the lipid mixture. Upon an abrupt temperature quench of the system into the two-phase coexistence region of the phase diagram, a power-law domain growth is observed, as predicted theoretically and observed experimentally. For certain ranges of the membrane compositions and temperatures it is found that the Brownian motion of lipid molecules shows strong deviations from the normal diffusion law. In cases where the membrane shows critical fluctuations, results of simulated single particle tracking and fluorescence correlation spectroscopy experiments show transient subdiffusion behavior spanning several orders of magnitude in time.