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BP: Fachverband Biologische Physik

BP 3: Membranes and Interfaces

BP 3.2: Talk

Monday, March 26, 2007, 14:30–14:45, H43

Energy barriers for membrane fusion — •Andrea Grafmueller and Reinhard Lipowsky — Max-Planck-Institut of Colloids and Interfaces, Potsdam, Germany

The fusion of bilayer membranes and vesicles has been studied using Dissipative Particle Dynamics (DPD) simulations. A large number of fusion attempts between a vesicle and a planar membrane segment is monitored varying the area per lipid molecule which determines the initial membrane tension. Fusion events are observed with a high success rates at high tensions. For these successful events, the fusion time, i.e., the time from first contact between the bilayers until the opening of the pore, shows a strong, exponential dependence on the membrane tension. The observed fusion process starts with the adhesion of the vesicle to the tense planar segment. Inter-bilayer flipflops disturb the bilayer order near the rim of the adhered area. Finally, the molecules in this disordered region reorganize into a small segment of a single (hemifused) bilayer, which ruptures at the edge. A detailed analysis of the observed fusion events reveals that these events are governed by at least two successive energy barriers.