Because of the multiplicity of possible equilibria in metal-peptide solutions, a new study using multifrequency EPR in combination with computer simulations and second-derivative displays was attempted. This approach permitted the determination with good precision of a set of spin Hamiltonian input parameters for the Cu-GlyHis and Cu-HisGly complexes. Two different arrangements in the first coordination sphere of copper were determined. In the case of the Cu-GlyHis complex, the simultaneous presence of the monomer and the bis complex and their relative percentages were established. For the Cu-HisGly complex, histamine-like coordination is proposed with a limited deviation from planarity. Spectral results obtained at room temperature for fast-tumbling copper complexes provided confirmation of the biological validity of the models. Molecular orbital coefficients characteristic of metal-ligand bonds were derived for effective D4h symmetry. The influence of the coordination modes on the covalent and ionic character of the metal-ligand bonds is discussed. © 1993, American Chemical Society. All rights reserved.

Pogni, R., Della Lunga, G., Basosi, R. (1993). Multi-Microwave Frequency ESR in the Structural Characterization of Copper(II) Dipeptide Complexes. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 115(4), 1546-1550 [10.1021/ja00057a047].

Multi-Microwave Frequency ESR in the Structural Characterization of Copper(II) Dipeptide Complexes

Pogni, Rebecca;Basosi, Riccardo
1993-01-01

Abstract

Because of the multiplicity of possible equilibria in metal-peptide solutions, a new study using multifrequency EPR in combination with computer simulations and second-derivative displays was attempted. This approach permitted the determination with good precision of a set of spin Hamiltonian input parameters for the Cu-GlyHis and Cu-HisGly complexes. Two different arrangements in the first coordination sphere of copper were determined. In the case of the Cu-GlyHis complex, the simultaneous presence of the monomer and the bis complex and their relative percentages were established. For the Cu-HisGly complex, histamine-like coordination is proposed with a limited deviation from planarity. Spectral results obtained at room temperature for fast-tumbling copper complexes provided confirmation of the biological validity of the models. Molecular orbital coefficients characteristic of metal-ligand bonds were derived for effective D4h symmetry. The influence of the coordination modes on the covalent and ionic character of the metal-ligand bonds is discussed. © 1993, American Chemical Society. All rights reserved.
1993
Pogni, R., Della Lunga, G., Basosi, R. (1993). Multi-Microwave Frequency ESR in the Structural Characterization of Copper(II) Dipeptide Complexes. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 115(4), 1546-1550 [10.1021/ja00057a047].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/7145
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