Specific binding of integrin αIIbβ3 to RGD peptide immobilized on a nitrilotriacetic acid chip:: A surface plasmon resonance study

Nitrilotriacetic acid has been routinely used in protein purification for its high affinity for His-tagged protein in the presence of Ni2+. Here we reported a type of nitrilotriacetic acid chip (NTA-chip) prepared by transferring NTA-DOGS containing a lipid monolayer to a 50 nm thick gold layer deposited on a glass slide. The surface binding ability of His-tagged protein and regeneration of NTA chip were characterized using a synthetic polypeptide PI (His-His-His-His-His-His-epsilon-aminohexanoic-Gly-Gly-Arg-Gly-Asp-Ser). The effect of divalent cations on integrin binding affinity for RGD ligand was investigated after PI had been immobilized onto the sensor chip. The results show that the NTA-chip is a useful tool to immobilize His-tagged protein on the chip surface, and can provide a functional orientation for further investigation. The results also show that removing of Ca2+ bound on low affinity sites or adding of Mn2+ can increase the binding ability of integrin.