Complex Formation of Zinc(II) Ion with Glycylglycyl-L-histidine : An Investigation by Proton Nuclear Magnetic Resonance Spectroscopy

Abstract

A proton nuclear magnetic resonance (¹H-NMR) study of the interaction of zinc(II) ion with glycylglycyl-L-histidine (Gly-Gly-His) was carried out. The addition of zinc(II) ion affected the NMR spectrum of Gly-Gly-His above pH 6; the signal of the imidazole C-2 proton underwent line broadening and upfield shift, and that of the methylene proton of glycine at the amino terminal was also shifted upfield. It is suggested that Gly-Gly-His functions as a bidentate ligand, coordinating with the zinc(II) ion through the amino nitrogen and the neighboring peptide oxygen, and that the imidazole nitrogen of the complex is linked intermolecularly to the zinc(II) ion of another peptide complex.