Interaction of α-Helical Glycopeptides with Lipid Bilayer Membrane

Abstract

Abstract α-Helical polypeptides having a glyco moiety at one end and a fluorescent probe at the other were prepared and investigated on the interaction with a lipid bilayer membrane. A glycopeptide composed of poly(alanine) and maltose was incorporated into the lipid membrane with the glyco moiety exposed to the aqueous phase and the peptide chain buried in membrane above the phase-transition temperature of the lipid membrane. However, below the phase-transition temperature, the glycopeptide induced the aggregation of dimyristoylphosphatidylcholine (DMPC) small unilamellar vesicles (SUV). Another glycopeptide composed of poly(γ-benzyl glutamate) and glucose also induced the aggregation of DMPC SUV, indicating that such the hydrophobic peptide tends to disturb the membrane structure significantly upon binding. The arrangement of the glycopeptide in a membrane was investigated by using a fluorescent probe connected to the end of the peptide chain. The terminal region of the peptide chain was located at the hydrophobic core of lipid membrane. However, the glycopeptide composed of 25 Ala residues had a smaller fraction taking perpendicular orientation to the membrane than that composed of 15 Ala residues. It was therefore considered that a part of the former glycopeptide molecules exits on the membrane surface, forming aggregates.