Lateral pressure effects on the properties of DPPC model membranes: Molecular Dynamics simulations

A. SERGIO GARAY; J. FRANCO QUARANTA; RODRIGUES DANIEL E.

San Javier, Tucumán

Congreso; XLI Reunión de la Sociedad Argentina de Biofísica; 2012

Sociedad Argentina de Biofísica

Cell membranes contain hundreds of lipid species and proteins arranged in heterogeneous domains. Nowadays it is known that this compositional and morphological heterogeneity is central to their functions of substance trafficking, topological adaptations, and sinergetic to protein interactions. It is therefore necessary to rationalize how the lateral pressure boundary conditions affect the structure, ordering and interactions within the lipid domains. We performed Molecular Dynamics simulations (MD) of model hydrated lipid bilayers of DPPC in Gel(T=22°C) and Liquid crystalline(T=50°C) phases, at several lateral pressure values (ensemble of constant surface tension) to evaluate its influence in the structural and ordering properties. For both phases the MD were performed over a bilayer of 480 lipids, at ST values of 14 and 28 dyn/cm, being the former that which reproduces the experimental NMR Deuterium Order Parameter profiles of the LC-phase. We evaluated the change in area per lipid, thickness, DOP, diffusion coefficient, and hydration of the interfaces. It is found that the area per lipid is much more dependent of the lateral pressure in the LC phase. Also the changes in the lateral pressure profiles normal to the bilayer direction are considered to disentangle the various interactions that originate contributions to interfacial energy from different depth in the membrane.