Co-ordination properties of cyclopeptides. Formation and stability of zinc(II) and copper(II) complexes of histidine-containing cyclopeptides, or imidazole
obtained for the formation of chelate rings of unusual size. The thermodynamic quantities associated with copper(II) complexformation with cyclo(-Gly-His-) were determined. The role of the different stereochemical requirements of copper(II) and zinc(II) in the formation of large chelate rings was assessed by means of previously reported data concerning the copper(II)–cyclo(-His-His-) complexes.
l-Histidyl-glycyl-glycyl-l-histidine. Amino-acid structuring of the bleomycin-type pentadentate metal-binding environment capable of efficient double-strand cleavage of plasmid DNA
A tetrapeptide, L-histidyl-glycyl-glycyl-L-histidine (HGGH), was synthesized and the pUC19 plasmid DNA cleaving activity by copper(II) complex of HGGH (Cu(II)-HGGH) was investigated. Cu(II)-HGGH showed bleomycin-like DNA cleaving activity and, at 50 nM, converted a supercoiled DNA efficiently to a linear DNA in the presence of 500 mu M H2O2/sodium ascorbate through an oxidative pathway. (C) 2015 Elsevier Inc. All rights reserved.