Interaction of Apolipoprotein Model Peptides with Liposomes: A High Performance Liquid Chromatography Study

The apparent partition constants of two amphiphilic peptides, Amp1 and Amp2, for partitioning into phosphatidylglycerol/phosphatidylcholine bilayer were measured using size-exclusion high performance liquid chromatograph. The exposed amino groups of vesicle-bound peptides were studied by TNBS assay. It was proposed that their N-terminals were exposed to the aqueous phase, and that the main explanation for the stronger interaction of Amp1 with lipid bilayer compared with Amp2 was its stronger lipid binding ability, though Amp1 was also buried deeper in the lipid membrane. It was also found that the two peptides were polymerized in buffer, with their amino groups almost totally buried within the polymers.