Lipid Phase Separation


Cell membranes contain a variety of lipids. When specific combinations of lipids are mixed, phase separation can occur which may induce raft formation. We study the phase behavior of model membranes composed of (DLPC)1,2 dilauroyl-sn-glycero-3-phosphocholine and (DSPC)1,2-distearoyl-glycero-3-phosphocholine mixtures. Molecular Dynamics (MD) is used in this study with both atomistic and coarse-grained* (CG) models. For instance we performed coarse grained molecular dynamics simulations at microsecond length scale to study the spatio-temporal mode of lipid reorganization affecting two component lipid bilayer patterns. The figure shows a patterned bilayer of two lipid types. Coexistence of fluid and gel phases is depicted by the rotational correlation function for the C_1 centers in the lipids tails, for symmetric-asymmetric DSPC domains, (l) is for (single) leaflet and (b) for bilayer. The reorientation functions in red are slow, and in blue are fast. DLPC-DSPC analysis of bilayer configurations show that at the nano-scale preferred patterns are those that minimize the hydrophobic mismatch.

* J Phys Chem B 2004,108, 750-760.

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