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Copper(II) complexes of oligopeptides containing aspartyl and glutamyl residues: potentiometric and spectroscopic studies

Kállay, Csilla and Várnagy, Katalin and Micera, Giovanni and Sanna, Daniele and Sóvágó, Imre (2005) Copper(II) complexes of oligopeptides containing aspartyl and glutamyl residues: potentiometric and spectroscopic studies. Journal of Inorganic Biochemistry, Vol. 99 (7), p. 1514-1525. ISSN 0162-0134. Article.

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DOI: 10.1016/j.jinorgbio.2005.04.009

Abstract

Copper(II) complexes of di-, tri- and tetra-peptides built up from Asp and/or Glu residues were studied by potentiometric and various spectroscopic techniques including UV–visible, circular dichroism and electron paramagnetic resonance measurements. The ligands contain two to five carboxylate functions and it generally results in the enhanced metal binding ability of the ligands, which is especially true for the oligopeptides of aspartic acid. In the case of peptides containing aspartyl residue in the N-terminal position the stability enhancement is reflected in the equilibrium data of the species [CuL] containing the (NH2, β-COO)-coordination mode in a 6-membered chelate. In the case of AspAsp and AspAspAsp the (NH2, N−, β-COO) and (NH2, N, N, β-COO)-coordination modes will be favoured, which contain (5,6) and (5,5,6)-joined chelate ring systems, respectively. The outstanding stability of the latter binding mode and the high negative charge of the corresponding species suppresses the metal ion coordination of the third amide function of AspAspAspAsp. It is also important to note that the presence of side chain carboxylate functions results in the formation of carboxylato-bridged polynuclear complexes in medium pH range. The extent of oligomerisation can be significantly enhanced by the increase of concentration and by the decrease of temperature.

Item Type:Article
ID Code:1434
Status:Published
Refereed:Yes
Uncontrolled Keywords:Aspartic acid, glutamic acid, peptides, copper(II), stability constants
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
002 Altri enti e centri di ricerca del Nord Sardegna > CNR-Consiglio Nazionale delle Ricerche > Istituto di chimica biomolecolare, Sassari
Publisher:Elsevier
ISSN:0162-0134
Additional Information:Pubblicato online il 31 maggio 2005.
Deposited On:18 Aug 2009 10:05

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