The effect of the ring size of fused chelates on the thermodynamic and spectroscopic properties of peptide complexes of copper(II)

Daniele Sanna, Csaba Gábor Ágoston, Giovanni Micera, Imre Sóvágó

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Abstract

Copper(II) complexes of the tripeptides GlyGly-β-Ala, Gly-β-AlaGly, β-AlaGlyGly, Gly-β-Ala-β-Ala, β-AlaGly-β-Ala, β-Ala-β-Ala-β-Ala and the tetrapeptides GlyGlyGly-β-Ala, GlyGly-β-AlaGly, Gly-β-AlaGlyGly and β-AlaGlyGlyGly were studied by potentiometric, EPR and UV-Vis spectroscopic methods. The stoichiometry of the complexes of peptides containing β-alanine residues are very similar to those of oligoglycines; [CuL]+, [CuL2], [CuH-1L], [CuH-2L]-, [CuH-1L2]- and [CuH-3L]2- were detected as the major species in all cases. The presence of β-alanine residues, however, influenced both thermodynamic stability and coordination geometry of various complexes. In most cases the formation of six-membered chelate rings resulted in a decrease of thermodynamic stability and distortion of coordination geometry of peptide complexes, especially if β-alanine residues were present in N-terminal or adjacent positions. On the contrary, the formation of the mixed (5,6,5) and (5,5,6) linked chelate systems of tripeptides is favoured over the pure five-membered rings.

Original languageEnglish
Pages (from-to)3079-3090
Number of pages12
JournalPolyhedron
Volume20
Issue number26-27
DOIs
Publication statusPublished - Dec 1 2001

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Keywords

  • Chelate ring size
  • Copper(II) complexes
  • EPR
  • Peptides
  • Potentiometry
  • β-alanine

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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