SYNTHESIS AND EVALUATION OF OLIGOPEPTIDES EXHIBITING CELL-ATTACHMENT ACTIBITY FOR MEDICAL USE

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Arg-Gly-Asp-Xaa (RGDX) sequence is a cell-adhesion motif present in several matrix-associated adhesive glycoproteins including fibronectin, vitronectin, and fibrinogen. The RGDX sequence is recognized by several integrins, including the platelet, fibroblast cell, and so on. It has been demonstrated that soluble peptides containing the RGD sequence compete with RGD-containing insoluble matrix proteins for binding to their respective integrins, and thus prevent cell-matrix adhesion. However, the affinity of the short synthetic peptides to their corresponding integrins is lower than that of proteins. In this work, we designed and synthesized Arg-Gly-Asp-Ser (RGDS) mimetic peptides for the purpose of improving the cell attachment activity of RGDS oligopeptide, and their cell-attachment activities were assayed by platelet aggregation inhibition method. Then we discussed on the structure and activity relationship of RGDS mimetic peptides.RGDS and its mimetic peptides were synthesized using l … More iquid phase procedures. The crude peptides were purified by HPLC. All peptides were characterized by NMR, MALDI-TOF MS, amino acid analysis, and elemental analysis. The effects of peptide on platelet function were directly measured by a platelet aggregation assay. The platelet aggregation in human platelet-rich plasma (PRP) was induced by adenosine 5'-diphosphate (ADP).Arg-Gly-Asp-Ser, Har-Gly-Asp-Ser, Can-Gly-Asp-Ser and Arg-Nip-Asp-Ser peptides inhibited the platelet aggregation reaction. The Asp-residue exchanged peptide, such as Arg-Gly-Glu-Ser, Arg-Nip-Glu-Ser, and Arg-Gly-Asn-Ser, show no inhibition effects for the platelet aggregation. The inhibitory activity of Arg-Nip-Asp-Ser was almost as same as that of RGDS. However, activities of Har-Gly-Asp-Ser and Can-Gly-Asp-Ser were significantly lower than that of RGDS. These result suggested that the side-chain length and flexibility of methylene residue were important factor exhibiting cell attachment activity, and also that the guanidino residue of Arg locates in the suitable position for playing the important role as the ligand for the receptor on the cell surface. Their results indicated that the carbonyl group and chain length of the side-chain of Asp residue and the guanidino groups and flexibility of the side-chain of Arg residue would play the important role as the ligand for the integrin receptor on the platelet membrane. Less