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

Arg-Gly-Asp-Xaa（RGDX）序列是存在于包括纤连蛋白、玻连蛋白和纤维蛋白原的几种基质相关粘附糖蛋白中的细胞粘附基序。RGDX序列被多种整合素识别，包括血小板、成纤维细胞等，已证实含有RGD序列的可溶性肽与含有RGD的不溶性基质蛋白竞争结合各自的整合素，从而阻止细胞-基质粘附。然而，短合成肽对其相应的整合素的亲和力低于蛋白质。为了提高RGDS寡肽的细胞粘附活性，设计合成了Arg-Gly-Asp-Ser（RGDS）模拟肽，并采用血小板聚集抑制法测定了其细胞粘附活性。在此基础上，探讨了RGDS模拟肽的构效关系。 ...更多信息 液相程序。通过HPLC纯化粗肽。所有的肽通过NMR、MALDI-TOF MS、氨基酸分析和元素分析表征。肽对血小板功能的影响通过血小板聚集测定直接测量。用5 ′-二磷酸腺苷（ADP）诱导人富血小板血浆（PRP）中血小板聚集，Arg-Gly-Asp-Ser、Har-Gly-Asp-Ser、Can-Gly-Asp-Ser和Arg-Nip-Asp-Ser肽对血小板聚集反应有抑制作用。天冬氨酸残基交换肽如Arg-Gly-Glu-Ser、Arg-Nip-Glu-Ser和Arg-Gly-Asn-Ser对血小板聚集无抑制作用。Arg-Nip-Asp-Ser的抑菌活性与RGDS相当。而Har-Gly-Asp-Ser和Can-Gly-Asp-Ser的酶活性显著低于RGDS。这些结果表明，亚甲基侧链的长度和柔性是影响细胞粘附活性的重要因素，也表明Arg的胍基残基位于合适的位置，作为细胞表面受体的配体发挥重要作用。结果表明，天冬氨酸残基侧链的羰基和链长以及精氨酸残基侧链的胍基和柔性将作为血小板膜上整合素受体的配体发挥重要作用。少

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