Interaction of the Hepatitis A peptide VP3(110-121) with lipid mono and bilayer models of cellular membranes

The surface activity of HAV-VP3(110-121) peptide was studied at different concentrations in an aqueous solution. Saturation was reached at 0.62μM concentration. The ability of the peptide to insert into monolayers of CL, SA, DPPC, DPPC/5% CL and DPPC/5% SA was also performed. Mixed monolayers composed of this peptide and the lipid mixtures were also studied as far as the miscibility of the two components is concerned. The mixed monolayers showing small negative deviations from ideality. The values of excess free energy of mixing (ΔG(M)(E)) suggest that the energy associated to the miscibility process is almost nonsignificant except for a 0.2 molar fraction of DPPC/SA and 0.6 molar fraction of DPPC/CL. The peptide has an expanding effect upon the monolayers but due to its amphoteric character this interaction is not dependent on the electrical charge of the lipids. In fluorescence studies, the peptide showed some degree of interaction with the lipid polar heads, but no interactions were detected with its alkylchains. This results show that after incubation with DPPC/5% CL and DPPC/5% SA liposomes the peptide remains in the outer part of the bilayers.