J. Ueda, N. Ikota, A. Hanaki
1987
Citations
0
Influential Citations
21
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract The complex formations of L-histidylglycyl-L- histidylglycine (His-Gly-His-Gly) and L-histidyl-L- histidylglycylglycine (His-His-Gly-Gly) with copper- (II) ion were studied in a slightly alkaline medium by visible absorption, circular dichroism and electron spin resonance spectroscopies. His-Gly-His-Gly coordinates to copper(II) ion via a terminal amino nitrogen, two deprotonated peptide nitrogens and an imidazole nitrogen of the histidyl residue in the third position. The copper(II) ion in the His-His- Gly-Gly complex is coordinated by three nitrogen donors; i.e. , a terminal amino nitrogen, an adjacent deprotonated peptide nitrogen and an imidazole nitrogen of the histidyl residue in the second position. The imidazole nitrogen at the N-terminal does not participate in the chelate formation with the copper(II) ion, but it bridges between the two monomeric complexes so that a broad ESR spectrum without the hyperfine structure is observed.