Nickel(II) complexes of oligopeptides containing aspartyl and glutamyl residues. Potentiometric and spectroscopic studies

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Abstract

Nickel(II) complexes of di-, tri- and tetra-peptides built up from Asp and/or Glu residues have been studied by potentiometric, UV-Vis and circular dichroism spectroscopic methods. The stoichiometry of the complexes are the same as in the case of common oligopeptides, but the presence of the side chain carboxylate groups results in differences in their stabilities and coordination modes. The presence of the β-carboxylate groups increases the metal binding affinity of the peptides in all cases. This is due to the coordination of the first, second and third aspartic acid residue in the case of the NiL, NiH-1L and NiH-2L complexes, respectively. The high negative charge of Asp4 suppresses the metal ion coordination of the third amide function, therefore the NiH-3L complex does not form with this tetra-peptide. In the case of peptides containing glutamic acid, no stability enhancement appears because there is only a weak interaction between the nickel(II) ion and the γ-carboxylate group, which is not able to compensate the disfavoured effect of the increasing negative charge of the complexes.

Original languageEnglish
Pages (from-to)811-817
Number of pages7
JournalPolyhedron
Volume26
Issue number4
DOIs
Publication statusPublished - Mar 1 2007

Keywords

  • Aspartic acid
  • Glutamic acid
  • Nickel(II)
  • Peptides
  • Stability constants

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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