ESR studies of Cu(histidine), in the presence of excess histidine at two microwave frequencies were undertaken to support either the glycine-like or histamine-like complexes. Low-frequency, S-band data are well-resolved for the M, = -I/* line in the gH region, and the number of lines is attributed to four approximately equivalent nitrogen donor atoms. When the pH is increased from 6.8 to 7.3, a second form is detected from the MI= line in the g,,re gion but not in other portions of the spectrum. The change in ESR parameters does not appear to be large enough to account for a change from four nitrogen donor atoms to three nitrogen donor atoms in the square-planar configuration. This small change is more consistent with a change in axial coordination or a change from four nitrogen donor atoms to an altered sef of four nitrogen donor atoms. Further ESR analysis of frozen copper- histidine complexes in the presence of excess histidine where the I4N isotope in the imidazole ring is substituted with l5N is consistent with a structure for which four equivalent ISN nitrogen donor atoms are bound to cupric ion.

Basosi, R., Valensin, G., Gaggelli, E., Froncisz, W., PASENKIEWICZ GIERULA, M., ANTHOLINE W., E., et al. (1986). Multifrequency ESR of copper(II)-(His)n (His = histidine). 1. Immobile phase. INORGANIC CHEMISTRY, 25(17), 3006-3010 [10.1021/ic00237a016].

Multifrequency ESR of copper(II)-(His)n (His = histidine). 1. Immobile phase

BASOSI, RICCARDO;VALENSIN, GIANNI;GAGGELLI, ELENA;
1986

Abstract

ESR studies of Cu(histidine), in the presence of excess histidine at two microwave frequencies were undertaken to support either the glycine-like or histamine-like complexes. Low-frequency, S-band data are well-resolved for the M, = -I/* line in the gH region, and the number of lines is attributed to four approximately equivalent nitrogen donor atoms. When the pH is increased from 6.8 to 7.3, a second form is detected from the MI= line in the g,,re gion but not in other portions of the spectrum. The change in ESR parameters does not appear to be large enough to account for a change from four nitrogen donor atoms to three nitrogen donor atoms in the square-planar configuration. This small change is more consistent with a change in axial coordination or a change from four nitrogen donor atoms to an altered sef of four nitrogen donor atoms. Further ESR analysis of frozen copper- histidine complexes in the presence of excess histidine where the I4N isotope in the imidazole ring is substituted with l5N is consistent with a structure for which four equivalent ISN nitrogen donor atoms are bound to cupric ion.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/33325
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