Biophysical studies of lipopeptide-membrane interactions.

There are a number of naturally occurring motifs for lipidation of peptides and proteins. In cases in which this involves adding a single hydrocarbon chain to the peptide, it is either a fatty acid or an isoprenyl group. Lipopeptides will partition between membrane and aqueous phases. When only one hydrocarbon chain is attached to the peptide, the affinity of the lipopeptide for the membrane is only marginally increased over that of the free peptide. The resulting partitioning is largely determined by the extent of the interaction of the peptide moiety with the membrane. In contrast, lipidation involving two hydrocarbon chains, either as two single chains attached at distinct locations of the peptide or a double-chain lipid anchor, firmly attaches the lipopeptide to the membrane. This can allow the placement of specific binding sites on a membrane surface. Such a strategy can be used, for example, to place specific antibodies on the surface of drug-carrying liposomes for the purpose of targeting drug delivery. In addition, lipopeptides will alter the physical properties of membranes. One of these effects is to increase the bilayer to hexagonal phase transition temperature. Substances having this property may also alter functional properties of membranes. While it is unlikely that these changes in the biophysical properties of the membranes. While it is unlikely that these changes in the biophysical properties of the membrane are responsible for specific functions of lipopeptides, such changes may be used to modulate certain properties of a membrane, such as the rate of viral fusion.