Synthesis, characterization and DNA binding and cleavage properties of copper(II)-tryptophan-tryptophan complex

1638-1643Reaction of copper(II) with tryptophan-tryptophan yields a 1:2 chloro bis(trp-trp) cuprate(II) complex. The complex exhibits absorption band at 620 nm (ε = 130 M -1 cm-1), which suggests a square pyramidal geometry at Cu(II) as observed for other Cu(II)-peptide complexes. The giso value of 2.09 for the complex agrees with a Cu(II) environment of distorted square pyramidal geometry. The mononuclear complex binds to calf thymus DNA through moderate intercalative and weak covalent interactions. It converts the supercoiled plasmid pUC19 DNA to the nicked circular form under physiological conditions

Interaction of Ni(II)-ethylenediamine/histamine with histidylglycine and investigation of their DNA cleavage abilities

761-768The interaction of Ni(II)-ethylenediamine (en)/histamine(hist) with histidylglycine(his-gly) and their DNA cleavage abilities have been investigated. The stability constants for the Ni(II)-en-his-gly (1) and Ni(II)-hist-his-gly (2) complexes have been determined at 298.0 K and 0.10 M (KNO3) ionic strength. Both the 1:1:1 ternary complexes have been corroborated by species distribution curves and ESI-MS analysis. The complex geometries have been analyzed by UV-vis experiments and molecular mechanics simulations. The DNA binding abilities of these complexes have been established by UV-vis-absorption, thermal-denaturation and fluorescence spectroscopy. The intrinsic binding constants for the bound complexes, Ni(II)-en-his-gly:DNA and Ni(II)-hist-his-gly:DNA, have been determined to be 280 and 420 M-1 respectively. Gel-electrophoresis experiments reveal that 1 and 2 cleave supercoiled DNA (type-I) to the nicked-circular (type-II) form hydrolytically at physiological pH. A tentative mechanism is proposed for the cleavage

A new S<SUB>4</SUB>-ligated zinc-peptide 1 : 2 complex for the hydrolytic cleavage of DNA

A new sulfur-ligated Zn-peptide 1 : 2 complex, [ZnII(Boc-NH-Cys-Gly-Cys-OMe)2]2- (2), was prepared, characterized, and tested for its DNA-binding and -cleavage properties. Complex 2 was found to cleave DNA hydrolytically. The negative charge in 2 reduces the affinity of the complex for DNA, and enhances its binding specificity

A 1 : 2 copper(II)-tripeptide complex for DNA binding and cleavage agent under physiological conditions

A 1 : 2 copper-tripeptide complex, [CuII(Boc-His-Gly-His-OMe)2]2+, was synthesized and structurally characterized. The absorption band at 577 nm suggests a square-planar geometry around CuII. The DNA-binding and DNA-cleavage properties of the CuII complex were investigated. The complex binds to calf thymus DNA (CT DNA) in an intercalative fashion and cleaves plasmid pUC-19 DNA hydrolytically at micromolar concentrations under physiological conditions. The intrinsic binding constant (Kb = 1.2&#215;102 M-1) for the binding of Cu-tripeptide complex with DNA suggests that this complex is suitable for rapid diffusion on the pharmacological time scale