Architecture of Peptide Assembly in Liposome

Abstract

Two chains of amphiphilic α-helical dodecapeptides were connected to a cyclic octapeptide in a parallel or antiparallel arrangement. Conformation, orientation, and association of the dodeca-peptide chains in the presence of dimyristoylphosphatidylcholine (DMPC) liposome were studied. The peptides were easily incorporated into the bilayer membrane. CD measurements revealed that the dodecapeptides took a distorted a-helix conformation due to intramolecular association. Fluorescence quenching measurement of a probe connected to each terminal region of the dodecapeptides revealed that the dodecapeptide chain was located on the membrane surface with a parallel orientation to the surface. Thermal denaturation of the helical structure was suppressed by connecting the two dodecapeptide chains to the cyclic peptide. These experimental results indicate that a supersecondary structure composed of associated α-helices was constructed on the surface of DMPC liposome by using a cyclic peptide as a template.