Interaction of a hydrophobic model peptide and its fatty acid derivative with lipid vesicles

The interaction of a peptide [Lys-Phe-Phe-Phe-Ile-Ile-Trp-OCH3] and its fatty acid derivatives [Lys-(epsilon-palmitoyl)-Phe-Phe-Phe-Ile-Ile-Trp-OCH3 and Lys-(epsilon-12-(9-anthroyloxy)stearic acid)-Phe-Phe-Phe-Ile-Ile-OCH3] with model membranes was investigated by fluorescence spectroscopy. The emission characteristics of the Trp fluorophore indicated that only the peptide with the fatty acid chain is associated with lipid vesicles. Quenching experiments with spin probes suggest an orientation for the fatty acylated peptide wherein the fatty acid chain is perpendicular to the bilayer surface and the peptide chain parallel to the bilayer surface.