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Bioinorganic Chemistry and Applications
Volume 2007, Article ID 30394, 9 pages
Research Article

Thermodynamic and Structural Characterization of the Copper(II) Complexes of Peptides Containing Both Histidyl and Aspartyl Residues

1Department of Inorganic and Analytical Chemistry, University of Debrecen, Debrecen 4010, Hungary
2Department of Colloid and Environmental Chemistry, University of Debrecen, Debrecen 4010, Hungary
3Department of Chemistry, University of Ioannina, Ioannina 45110, Greece

Received 27 June 2007; Accepted 7 November 2007

Academic Editor: Martin Stillman

Copyright © 2007 Csilla Kállay et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Terminally protected pentapeptides with 2 histidines (Ac-HHVGD-NH2 and Ac-HVGDH-NH2) and the terminally free peptides containing both internal aspartyl and C-terminal histidyl residues (FDAH and VIDAH) have been synthesized, and copper(II) complexes studied by potentiometric, UV-Vis, CD, and EPR spectroscopic techniques in solution. Both thermodynamic and spectroscopic data reveal that side chain donor atoms of aspartyl and histidyl residues have a significant contribution to the metal binding affinity of peptide molecules. In the case of terminally protected peptides, the role of the imidazole-N donor functions is reflected in the enhanced stability of the 3N and 4N coordinated copper(II) complexes. The amino and β-carboxylate groups of FDAH and VIDAH create a very effective metal binding site with the (NH2, N, β-COO) and (NH2, N, N, β-COO) coordination modes including the N-termini, while the histidine sites are available for the formation of the (Nim, N, N) binding mode resulting in the preference of dinuclear complex formation.