Thermodynamic and spectroscopic characterization and in vitro O2 ? scavenger activity of copper(II) glycyl-L-histidyl-glycyl-L-histidine complexes

Copper(II) and zinc(II) complexes of the peptides Ac-HisValHis-NH 2 and Ac-HisValGlyAsp-NH 2 related to the active site of the enzyme CuZnSOD

“…In the case of Ac-HisValHis-NH 2 the pK values can be assigned to the imidazole rings of histidyl residues. The values obtained in this study are in good agreement with previous literature data reported for related ligands [16][17][18][19]. The difference of the two pK values is rather small (0.94 log units), suggesting that the deprotonation of the histidyl residues takes place in overlapping processes.…”

“…It is clear from Table 2 that in the case of Ac-HisValGlyAsp-NH 2 well-resolved CD spectra were obtained only for the amide coordinated species [CuBH À3 ] 2À and [CuBH À4 ] 3À . However, d-d transitions of the bis(ligand) complex of the free tetrapeptide ([CuD 2 ]) were characterised by the appearance of a positive Cotton effect at k ¼ 685 nm (De ¼ þ0:66), which is in a reasonable agreement with the histaminelike coordination of terminal His residue [17,18]. The major species [CuDH À3 ] 2À formed above pH 10 and its CD parameters are as follows: k ¼ 509 nm (De ¼ À1:46), k ¼ 310 nm (De ¼ þ1:75), k ¼ 272 nm (De ¼ À1:68), k ¼ 234 nm (De ¼ +4.20).…”

The cyclopeptides with the multi-His motif as ligands for copper(II)

“…For that reason the interactions between copper(II) and the peptides with one, two, three or more His residues have been intensively studied and well understood [1][2][3]. The multi-His oligopeptides show high specificity in the copper(II) binding by formation e.g.…”

Copper(II) Binding Modes in the Prion Octapeptide PHGGGWGQ: A Spectroscopic and Voltammetric Study

“…[1±7] Such complexes were thermodynamically and spectroscopically characterised and their capability to act as scavenger of O 2 À tested. [3,5,6] From these studies it has been possible to obtain useful information about the mechanism by which these complexes exert their antioxidant activity and then address the relationship between the measured activity and their structural properties. [3,5,6] Another useful strategy to study metal ± peptide interactions employs metal complexation to achieve the folding of polypeptidic chains into well-defined conformations.…”

“…[3,5,6] From these studies it has been possible to obtain useful information about the mechanism by which these complexes exert their antioxidant activity and then address the relationship between the measured activity and their structural properties. [3,5,6] Another useful strategy to study metal ± peptide interactions employs metal complexation to achieve the folding of polypeptidic chains into well-defined conformations. [8] The increasing number of reports about the introduction of metal binding sites into native and/or synthetic proteins, [9] as well as appropriately designed oligopeptides, [7,10] reveal that this is a currently active research field, which can provide useful information for the development of synthetic metalloproteins.…”