Interaction Between Tripeptide Gly-Gly-His and Cu2+ Probed by Microcantilevers

Gly-Gly-His (GGH) tripeptide was covalently attached onto a 3-mercaptopropionic acid (MPA) modified gold surface of microcantilever, and its interaction with Cu2+ was studied by microcantilever method. It was found that at a relatively high concentration of Cu2+, the cantilever bent toward the gold side initially with a tensile surface stress, which might be due to the N atom of imidazole ring and carboxyl group in different peptide coordinate with Cu2+. The reversal deflection of microcantilever was observed immediately, which suggest that the peptide-Cu2+ complex are formed with conformation transition. At a relatively low concentration of Cu2+, only the process of conformation transition was observed because the coordination mode might not be formed initially. The influences of pH and concentration of Cl− on the process above were studied. The results show that the maximum deflection was obtained at pH 7, and the bonding of Cu2+ to the Gly-Gly-His tripeptide was inhibited because of the formation of CuClx2−x.