New insights into the metal ion-peptide hydroxamate interactions: Metal complexes of primary hydroxamic acid derivatives of common dipeptides in aqueous solution

Péter Buglyó, Eszter Márta Nagy, Etelka Farkas, Imre Sóvágó, Daniele Sanna, Giovanni Micera

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24 Citations (Scopus)

Abstract

Complex formation of primary dipeptide hydroxamic acids, L-Ala-L-AlaNHOH and L-Ala-L-SerNHOH, as well as the corresponding Z-protected ones, Z-L-Ala-L-AlaNHOH and Z-L-Ala-L-SerNHOH (Z = benzyloxycarbonyl), with iron(III), aluminium(III), nickel(II), copper(II) and zinc(II) was studied in aqueous solution by pH-potentiometric and spectroscopic (UV-Vis, EPR, CD, 1H NMR) methods. The exclusive formation of [O,O] chelated hydroxamate complexes was found with iron(III) and aluminium(III) with all the ligands. Formation of linkage isomers with the involvement of either [O,O] hydroxamate or [NH2,CO] chelates was detected both in the zinc(II)-L-Ala-L-AlaNHOH and -L-Ala-L-SerNHOH systems. Upon increasing the pH, none of these chelating sets are capable of preventing the hydrolysis of the metal ion. The formation of stable complexes was found in the nickel(II) and copper(II) systems above pH ∼ 6 with a [NH2, Namide, Nhydrox.] binding mode after deprotonation and coordination of the peptide amide and the hydroxamate group. With an excess of copper(II), the formation of trinuclear [Cu3HxL2]x+4 type (x = -4 to -6) complexes as the major species was also detected. Blocking the terminal amino group in the Z-protected ligands results in a dramatic decrease of the nickel(II) and zinc(II) binding strengths, and insoluble complexes with copper(II). No indication was found for the role of the hydroxyl group of the serine moiety in metal ion binding.

Original languageEnglish
Pages (from-to)1625-1633
Number of pages9
JournalPolyhedron
Volume26
Issue number8
DOIs
Publication statusPublished - May 21 2007

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Keywords

  • Equilibrium
  • Metal complex
  • Micro constant
  • Peptide hydroxamic acid
  • Stability constant
  • pH-potentiometry

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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