Copper(II) complexes of dipeptides of histidine containing additional chelating bis(imidazol-2-yl) agent at the C-termini (PheHis-BIMA [N-phenylalanyl-histidyl-bis(imidazol-2-yl)methylamine] and HisPhe-BIMA [N-histidyl-phenylalanyl-bis(imidazol-2-yl)methylamine]) were studied by potentiometric, UV-Visible and Electron Paramagnetic Resonance (EPR) techniques. The imidazole nitrogen donor atoms of the bis(imidazol-2-yl)methyl group are described as the primary metal binding sites forming stable mono- and bis(ligand) complexes at acidic pH. The formation of a ligand-bridged dinuclear complex [Cu(2)L(2)](4+) is detected in equimolar solutions of copper(II) and HisPhe-BIMA. The coordination isomers of the dinuclear complex are described via the metal binding of the bis(imidazol-2-yl)methyl, amino-carbonyl and amino-imidazole(His) functions. In the case of the copper(II)-PheHis-BIMA system the [NH(2), N(-)(amide), N(Im)] tridentate coordination of the ligand is favoured and results in the formation of di- and trinuclear complexes [Cu(2)H(-1)L](3+) and [Cu(3)H(-2)L(2)](4+) in equimolar solutions. The presence of these coordination modes shifts the formation of "tripeptide-like" ([NH(2), N(-), N(-), N(Im)]-coordinated) [CuH(-2)L] complexes into alkaline pH range as compared to other dipeptide derivatives of bis(imidazol-2-yl) ligands. Although there are different types of imidazoles in these ligands, the deprotonation and coordination of the pyrrole-type N(I)H groups does not occur below pH 10. (C) 2003 Elsevier Inc. All rights reserved.

Acid-base properties and copper(II) complexes of di-peptides containing histidine and additional chelating bis(imidazol-2-yl) residues / Osz, K; Varnagy, K; Suli Vargha, H; Csampay, A; Sanna, D; Micera, Giovanni; Sovago, I.. - In: JOURNAL OF INORGANIC BIOCHEMISTRY. - ISSN 0162-0134. - 98:1(2004), pp. 24-32. [10.1016/j.jinorgbio.2003.09.009]

Acid-base properties and copper(II) complexes of di-peptides containing histidine and additional chelating bis(imidazol-2-yl) residues

MICERA, Giovanni;
2004

Abstract

Copper(II) complexes of dipeptides of histidine containing additional chelating bis(imidazol-2-yl) agent at the C-termini (PheHis-BIMA [N-phenylalanyl-histidyl-bis(imidazol-2-yl)methylamine] and HisPhe-BIMA [N-histidyl-phenylalanyl-bis(imidazol-2-yl)methylamine]) were studied by potentiometric, UV-Visible and Electron Paramagnetic Resonance (EPR) techniques. The imidazole nitrogen donor atoms of the bis(imidazol-2-yl)methyl group are described as the primary metal binding sites forming stable mono- and bis(ligand) complexes at acidic pH. The formation of a ligand-bridged dinuclear complex [Cu(2)L(2)](4+) is detected in equimolar solutions of copper(II) and HisPhe-BIMA. The coordination isomers of the dinuclear complex are described via the metal binding of the bis(imidazol-2-yl)methyl, amino-carbonyl and amino-imidazole(His) functions. In the case of the copper(II)-PheHis-BIMA system the [NH(2), N(-)(amide), N(Im)] tridentate coordination of the ligand is favoured and results in the formation of di- and trinuclear complexes [Cu(2)H(-1)L](3+) and [Cu(3)H(-2)L(2)](4+) in equimolar solutions. The presence of these coordination modes shifts the formation of "tripeptide-like" ([NH(2), N(-), N(-), N(Im)]-coordinated) [CuH(-2)L] complexes into alkaline pH range as compared to other dipeptide derivatives of bis(imidazol-2-yl) ligands. Although there are different types of imidazoles in these ligands, the deprotonation and coordination of the pyrrole-type N(I)H groups does not occur below pH 10. (C) 2003 Elsevier Inc. All rights reserved.
Acid-base properties and copper(II) complexes of di-peptides containing histidine and additional chelating bis(imidazol-2-yl) residues / Osz, K; Varnagy, K; Suli Vargha, H; Csampay, A; Sanna, D; Micera, Giovanni; Sovago, I.. - In: JOURNAL OF INORGANIC BIOCHEMISTRY. - ISSN 0162-0134. - 98:1(2004), pp. 24-32. [10.1016/j.jinorgbio.2003.09.009]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/83560
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