Hydrolytic Cleavage of DNA by Ternary Amino Acid Schiff Base Copper(II) Complexes Having Planar Heterocyclic Ligands

Chakravarty, Akhil R. ; Reddy, Pattubala A. N. ; Nethaji, Munirathinam (2004) Hydrolytic Cleavage of DNA by Ternary Amino Acid Schiff Base Copper(II) Complexes Having Planar Heterocyclic Ligands European Journal of Inorganic Chemistry, 2004 (7). pp. 1440-1446. ISSN 1434-1948

Full text not available from this repository.

Official URL: http://onlinelibrary.wiley.com/doi/10.1002/ejic.20...

Related URL: http://dx.doi.org/10.1002/ejic.200300514


The ternary copper(II) complexes [Cu(salgly)L] (L = phen, 1; dpq, 2), [Cu(salala)L] (L = phen, 3; dpq, 4) and [Cu(salphe)L] (L = phen, 5; dpq, 6), where salgly, salala and salphe are tridentate Schiff-base ligands derived from the condensation of salicylaldehyde with glycine, L-alanine and L-phenylalanine, respectively, are prepared and their nuclease activity studied (phen, 1,10-phenanthroline; dpq, dipyridoquinoxaline). The crystal structure of 3 displays a distorted square-pyramidal (4+1) coordination geometry in which the ONO-donor Schiff base is bonded to the metal atom in the basal plane. The chelating phen ligand displays an axial-equatorial mode of bonding. The complexes exhibit a d-d band near 670 nm and a charge transfer band near 370 nm in methanol. The one-electron paramagnetic complexes display axial EPR spectra in DMF glass at 77 K, indicating a {dx2-y2}1 ground state. The complexes are redox-active and exhibit a quasi-reversible CuII/CuI couple in DMF at approximately -0.6 V vs. SCE. They show catalytic activity in the oxidation of ascorbic acid by molecular oxygen. The ability of the complexes to bind calf thymus (CT) DNA follows the order: 2 ≈ 4 ≈ 6 > 1 ≈ 3 ≈ 5. Complexes 1-6 show oxidative DNA cleavage activity in the presence of mercaptopropionic acid as a reducing agent. All the complexes show hydrolytic cleavage activity in the absence of light or any reducing agent. The oxidative and hydrolytic DNA cleavage efficiencies follow the order: 2 ≈ 4 ≈ 6 > 1 ≈ 3 ≈ 5. The dpq complexes, which have a greater DNA binding ability, display enhanced nuclease activity than their phen analogues. The hydrolytic DNA cleavage rate of 1.8 h-1, observed for 2, is significantly high relative to most of the known copper-based synthetic hydrolases. Mechanistic pathways involved in the nuclease activity of the complexes are discussed.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons, Inc.
Keywords:Copper; Synthetic hydrolase; X-ray diffraction; Schiff bases; Phenanthroline bases
ID Code:6496
Deposited On:20 Oct 2010 10:38
Last Modified:27 May 2011 04:55

Repository Staff Only: item control page