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 differ ent concentrations in an aqueous solution. Saturation was reached at 0 .62 mu M concentration. The ability of the peptide to insert into mono layers of CLI 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 concer ned. The mixed monolayers showing small negative deviations from ideal ity. The values of excess Gee energy of mixing (Delta G(M)(E)) suggest that the energy associated to the miscibility process is almost nonsi gnificant except for a 0.2 molar fraction of DPPC/SA and 0.6 molar fra ction of DPPC/CL. The peptide has an expanding effect upon the monolay ers but due to its amphoteric character this interaction is not depend ent on the electrical charge of the lipids. In fluorescence studies, t he peptide showed some degree of interaction with the lipid polar head s, but no interactions were detected with its alkylchains. This result s show that after incubation with DPPC/5% CL and DPPC/5% SA liposomes the peptide remains in the outer part of the bilayers.