Dresden 2017 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
BP: Fachverband Biologische Physik
BP 48: Membranes and Vesicles II
BP 48.6: Vortrag
Donnerstag, 23. März 2017, 11:30–11:45, HÜL 386
Minimum-free-energy paths in membrane fusion: Coarse-grained molecular dynamics simulations — •Yuliya Smirnova and Marcus Müller — Georg August University, Institute for Theoretical Physics, Göttingen, Germany
Collective phenomena in membranes such as fusion and fission involve reorganization of many molecules. Such transformations do not occur spontaneously but require the crossing of large (compared to kBT) free energy barriers. Recent advances in free-energy calculation techniques, in particular, implementation of the so-called string method in MD simulations, allow us to study membrane transformations and calculate free energies along the transformation paths without a priori knowledge of the reaction coordinate. We focus on two initial stages of fusion: (1) bringing two membranes into close apposition and (2) forming an initial lipid connection (stalk) between the two apposed bilayers. With help of the string method, we calculated the minimum free-energy paths of stalk formation between two apposed membranes as a function of membrane separation, lipid composition, and tension. Within the range of membrane separation distances, which allow formation of at least a metastable stalk structure, the free energy-barrier is not sensitive to the separation distance, however, the excess free-energy of the stalk decreases substantially with decreasing distance. Changing lipids to more fusiogenic species or introducing tension does not change the free-energy barrier significantly. On the other hand, the free-energy contribution of bringing two membranes from large to small separation distance significantly decreases for more fusiogenic lipids.