Simulations of Phospholipids Using a Coarse Grain Model

A computationally efficient coarse grain model designed to closely mimic specific phospholipids is used to study a number of phospholipid systems to demonstrate its strengths and weaknesses. A study of a membrane containing an anesthetic, halothane, illustrates the shortcomings of this model in treating systems without extensive parametrization. In contrast, the power of the model is demonstrated by its ability to successfully simulate the self-assembly of two phospholipid phases from random initial configurations: a lamellar phase and a reverse hexagonal phase in a ternary system containing water, a hydrocarbon, and a phospholipid. The aqueous columns in the reverse hexagonal phase tend to adopt polygonal cross sections and the local structure of phospholipids is still bilayer-like. Molecular dynamics was found to be much more efficient at simulating self-assembly in the current systems than Monte Carlo.