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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|Titolo:||Multifrequency ESR of copper(II)-(His)n (His = histidine). 1. Immobile phase|
|Citazione:||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.|
|Appare nelle tipologie:||1.1 Articolo in rivista|