The Covalent Coupling of Arg-Gly-Asp-Containing Peptides to Liposomes: Purification and Biochemical Function of the Lipopeptide

With the advent of liposomes as drug carriers, there arises a need for efficient targeted deliveryin vivo.Proteins coupled to liposomes usually yield heterogeneous products that are ill-defined both chemically and in terms of spatial orientation. We now report on the disulfide linkage to the surface of intact liposomes of a peptide representing one-half of a ligand–receptor pair. An RGD-motif-containing peptide was coupled to the phospholipid PDP-DOPE of the liposomes by a thiol-disulfide exchange. The resulting lipopeptides were amenable to definition by TLC, HPLC, and MS and found to be in a functional orientation allowing biochemical interaction with their receptor, the integrin glycoprotein IIb-IIIa.