Immobilized liposome chromatography for analysis of interactions between lipid bilayers and peptides

Liposomes were sterically immobilized in gel beads to be used for isocratic chromatographic analysis of interactions between lipid bilayers, amino acids, and water-soluble peptides. Tryptophan was more retarded on the immobilized liposomes than were other amino acids, and peptides with C-terminal cysteine were much more retarded than were peptides with serine or aminobutyric acid instead of the cysteine. Peptide sequences could affect the peptide-liposome interactions. For peptides corresponding to polypeptide segments of a membrane protein, the human red cell glucose transporter (Glut1), the retention volumes increased with decreasing water-to-oil transfer free energy of the peptides and were related to the transfer free energy distribution within the peptides as shown by hydropathy plots and to the presence of cysteine. Among these peptides, the partially hydrophobic peptides 125GRFIIGVYCG134 and 201CIVLPFCPES210 and the hydrophilic peptide 421CFQYVEQLC429 were most strongly retarded on immobilized phosphatidylcholine liposomes. The results indicated that the peptide-liposome interactions were mainly of hydrophobic nature and that the structure of the interfacial head-group region of the lipid bilayers was important.