Molecular dynamics simulation of the hydrocarbon region of a biomembrane using a reduced representation model

The development of a coarse-grained reduced-representation model of the hydrocarbon region of a biological membrane is reported. The potential is based on the popular Gay-Berne model of liquid crystals, and involves the linking of individual Gay-Berne ellipsoids by harmonic springs to form each hydrocarbon chain. Diffusion coefficients and order parameters have been calculated by molecular dynamics computer simulations for a range of parameter sets. The results clearly demonstrate the presence of a phase transition from an ordered low-temperature solid phase reminiscent of the L-alpha phase of phospholipids, to a high-temperature disordered phase reminiscent of the L-alpha phase. Order parameters calculated for each layer of the model are consistent with the experimental segmental order parameters reported for dipalmitoyl phosphatidylcholine. The application of this model to the study of small molecule diffusion within the membrane core is proposed. (C) 2001 John Wiley & Sons, Inc.