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|Title:||Coordination behaviour of glycylglycine with zinc(II) in presence of -histidine, histamine and imidazole ligands|
|Authors:||Nair, M Sivasankaran|
Pillai, M Sankaranarayana
|Abstract:||Computer-based analysis of the pH titrations data obtained in aqueous perchlorate media at 37ᵒC and 1=0.15 mol dm-3 (NaClO4) for the zinc(II)-glycylglycine/glycinamide (A)--histidine and histamine (B) mixed ligand systems shows the presence of the mixed ligand species ZnABH and ZnAB, ZnAB arid ZnAB2 mixed species are formed in the zinc(II)-glycylglycine/glycinamide (A)-imidazole (B) systems. There is no evidence for the formation of the zinc(II) binary and mixed ligand species containing amide deprotonated dipeptide below pH 7.5. The results indicate that the dipeptide binds the metal through N-amino and O-peptido groups in the ZnABH and ZnAB mixed species as also in the ZnA or ZnA2 type of binary species. In the ZnABH species the extra proton is attached to the primary amino group of the -histidine or histamine secondary ligand (B). The carboxylate group of -histidine is also involved in coordination in both the ZnAB and ZnABH types of mixed species. It appears that the ZnAB2 species is more stable than the ZnAB species in the zinc(II)-glycylglycine/glycinamide (A)-imidazole (B).|
|Appears in Collections:||IJC-A Vol.29A(06) [June 1990]|
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