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BP: Fachverband Biologische Physik

BP 16: Biological Membranes I

BP 16.7: Talk

Tuesday, March 15, 2011, 12:15–12:30, ZEU 260

Molecular Dynamics simulations of phase separation of ternary lipid-cholesterol structure — •Davit Hakobyan and Andreas Heuer — WWU Münster, Institut für Physikalische Chemie, Corrensstraße 30, 48149 Münster, Germany

This project is supported by SFB 858

The separation of liquid-ordered and liquid-disordered phases of lipids in membranes is a subject of continued experimental and theoretical investigations. Yet, the driving force of phase separation is still to be understood. Comparison of energetic and entropic components between cholesterol-saturated lipid and cholesterol-unsaturated lipid complexes [1] indicates that phase separation is the consequence of a cooperative effect of lipids and cholesterols interactions. Here we present the results of coarse-grained (CG) simulations using MARTINI potential [2] for binary dipalmitoyl phosphatidylcholine (DPPC) /dilinoleyl phosphatidylcholine (DUPC) and ternary DPPC/DUPC/CHOL systems. Investigation of temporal evolution of order parameters as a function of nearest-neighbors shows rather clear distinction between systems with and without CHOL. For the former case the order parameter for the saturated DPPC is differentiated among nearest neighbors while for the latter case it is not, which might be thought of as a distinctive property of phase separated and mixed systems. The numerical analysis is complemented by studying a more detailed united atom model of the same system.

[1] Z. Zhang, et al., J. Phys. Chem. B, 111, 12888-12897, 2007.

[2] S.J. Marrink, et al., J. Phys. Chem. B, 111, 7812-7824, 2007.