Asymmetric partitioning of a polymer into a curved membrane

The partitioning of a flexible model polypeptide into curved and flat lipid bilayer model membranes has been investigated using Monte Carlo methods. It is shown that a curved lipid membrane exhibits a gradient of lipid density fluctuations across the bilayer. The fluctuations increase continuously from the side of lower curvature (outer layer) to the side of higher curvature (inner layer). It is found that curvature promotes partitioning of the polymer into the outer layer of the membrane. Moreover, it is shown that in the case of the curved bilayer, the polymer moves spontaneously from the outer to inner layer of the membrane, where it is subsequently localized. It is argued that the curvature-induced gradients of the fluctuations of the mean local lipid density and the local mean lipid orientation across the membrane is the entropical driving force for the observed translocation process. (C) 1995 American Institute of Physics.