Electrochemistry of copper(II)-peptide complexes containing histidine residues

Copper(II)-peptide complexes (peptide = GHL¹ 1 GHL = glycyl-L-histidyl-L-lysine; GHG = glycyl-L-histidylglycine; GH = glycyl-L-histidine; GGG = triglycine; GGH = glycyl-L-histidine., GHG and GH) were investigated in aqueous solution by various electrochemical methods. The electrode reaction was measured at various pH levels. The distribution profile of the species was determined using potentiometric titration. After considering the effect of electrostatic repulsion between charged electrode surface and GHL, the coordination structure of Cu(II)-GHL determined by the two methods was in agreement. Electroplating was used to investigate the adsorption mechanism of Cu(II)-GHL, and it was found that the adsorption of Cu(II)-GHL changed the coordination structure of Cu(II)-GHL, causing a shift in the reduction potential of adsorbed Cu(II)-GHL toward the reduction potential of free Cu(II) ion.