ASYMMETRIES OF A CURVED BILAYER MODEL MEMBRANE

The asymmetries of a simple model bilayer membrane with uniform curvature have been investigated using Monte Carlo methods. It is found that with increasing curvature the two layers of the membranes behave differently due to pure entropic effects. This is shown by means of three quantities; the densities of lipids, the orientational orders of the lipids, and the widths of the two layers. As an important characteristic of the asymmetry of curved bilayers, it is observed that the fluctuation of the orientational order in the inner layer can increase up to four times of its value for a planar bilayer, and can be more than two times larger than the fluctuations in the outer layer. The importance of the asymmetric fluctuations across a curved bilayer membrane for protein insertion into membranes is pointed out. © 1994 American Institute of Physics.