We present simulation data for a bilayer composed of a ternary mixture of cholesterol, dioloeoyl phosphatidylcholine anddipalmitoyl phosphatidylcholine. The composition is chosen to be in the two-phase region and the temmperature in thevicinity of the miscibility transition. Using the Anton special purpose computer to generate continuous trajectories longerthe ten microseconds, we find that liquid-liquid phase separation is supported by the Charmm36 empirical potential.The Anton simulation timescale enables complete mixing of the lipids, providing strong evidence that the observed phasecoexistence is robust. The time-and ensemble-averaged mean squared displacement (MSD) displays anomalous scaling on timescales less than 50 nsec and normaldiffusion on longer timescales. The short-time anomalous scaling is explained by a mode-coupling argument[Flenner et alPhys Rev E 79:011907(2009)]. The per-lipid MSD's suggest that a few lipids remain associated with the liquid ordered domainfor the duration of the simulation, suggesting a mechanism for anomalous transport on experimentally accessible timescales.

Modeling liquid-liquid phase separation and lipid transport on the Anton Supercomputer

245th National Meeting (2013)

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