Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 24: Posters: Membranes and vesicles

BP 24.14: Poster

Tuesday, March 17, 2015, 14:00–16:00, Poster A

Monte-Carlo 2D Model of Bilayer System — •Davit Hakobyan and Andreas Heuer — WWU Münster, Institut für Physikalische Chemie, Münster, Germany

Various Molecular Dynamics (MD) and 2D Monte-Carlo systems were proposed for investigation of the processes in model bilayer systems. Particularly, with help of a relatively simple 2D 3-particle lattice model the phase separation of saturated and unsaturated lipids and cholesterol was demonstrated [Reigada et al. 2008, DOI: 10.1063/1.2817333]. In this lattice model, however, different lipids and cholesterol were only differentiated by the size of the pair-wise interaction and lacked specific properties of lipids and cholesterol.

Here we introduce 2D models of basic bilayer components where their characteristic properties are taken into account. In this model the individual particles of the 2D system present lipids or cholesterol with additional information about the order parameter of the alkyl chain. The free energy of this system is decomposed into separate and carefully chosen entropic and enthalpic parts. The parameters and the balance of entropy and enthalpy for this 2D model were checked against the all-atom MD simulations to certify the adequateness. We further adapt the model to be able to observe phase separation of a ternary system with saturated and unsataurated lipids and cholesterol. In this way we can systematically explore the range of compositions and molecular properties for which phase separation is possible.