Comparison of mesoscopic phospholipid-water models

In this study we show how a coarse-grained model of a phospholipid can be developed and we study the parameter sets applied to the formation of a coarse-grained dimyristoyl phosphatidyl choline ( DMPC) bilayer. We create a model comprising a head group of three hydrophilic beads, to which two hydrophobic tails are connected. From results obtained with molecular dynamics simulations on a single lipid in water, a bond-bending potential between three subsequent beads was added. Using a bead volume of 90 Angstrom(3), we reproduce the experimental values of the area per lipid and the hydrophobic thickness. There is no linear relation between the repulsion parameter a(ij) and the level of coarse graining. The key factor in the formation of a lipid bilayer is the difference between the water - water and the water - hydrophobic tail repulsion parameters.