Peptides and liposomes: from biophysical to immunogenic studies.

Synthetic peptide sequences constitute a useful tool to understand protein related diseases. A preliminary study consists of the analysis of peptide interaction with model membranes. The simplest one is based on monomolecular films of lipids spread at the air-water interface that imitate the interfacial environment in which some proteins function. Monolayer methodology provides a reliable screen of the extent to which hydrophobic interactions, charges, dipole potentials and subphase composition drive protein-lipid interaction. One step forward is based on the use of liposomes (lipid-based vesicles) that were originally introduced in 1965 as models of lipid bilayer membranes. Later, they have been widely studied as drug delivery systems mainly due to their safety, structural versatility, composition, fluidity and also because of their ability to incorporate almost any molecule regardless of its structure. In this sense, liposomes have been used as carriers of proteins and peptide antigens. Antigenic materials can be attached to the outer surface, encapsulated within the internal aqueous spaces or reconstituted within the lipid bilayers of the liposomes. In the present review we describe the steps going from the selection of peptides related to viral hepatitis proteins to its diagnostic and therapeutic application, with special emphasis on the use of model membranes to predict peptide mode of interaction with the target cell.