Electrochemical, phosphate hydrolysis, DNA binding and DNA cleavage properties of new polyaza macrobicyclic dinickel(II) complexes

Anbu, Sellamuthu and Shanmugaraju, Sankarasekaran and Kandaswamy, Muthusamy (2012) Electrochemical, phosphate hydrolysis, DNA binding and DNA cleavage properties of new polyaza macrobicyclic dinickel(II) complexes. In: RSC ADVANCES, 2 (12). pp. 5349-5357.

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Abstract

A new class of macrobicyclic dinickel(II) complexes Ni2L1,2 B](ClO4)(4) (1-6), where L-1,L-2 are polyaza macrobicyclic binucleating ligands, and B is a N,N-donor heterocyclic base (viz. 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen)) are synthesized and characterized. The redox, catalytic, DNA binding and DNA cleavage properties were studied. They exhibit two irreversible waves in the cathodic region around E-pc = -0.95 V and E-pa = -0.85 V vs. Ag/Ag+ in CH3CN-0.1 M TBAP, respectively. The first order rate constants for the hydrolysis of 4-nitrophenylphosphate to 4-nitrophenolate by the dinickel(II) complexes 1-6 are in the range from 3.36 x 10(-5) to 10.83 x 10(-5) Ms-1. The complexes 3 and 6 show good binding propensity to calf thymus DNA giving binding constant values (K-b) in the range from 3.08 x 10(5) to 5.37 x 10(5) M-1. The binding site sizes and viscosity data suggest the DNA intercalative and/or groove binding nature of the complexes. The complexes display significant hydrolytic cleavage of supercoiled pBR322DNA at pH 7.2 and 37 degrees C. The hydrolytic cleavage of DNA by the complexes is supported by the evidence from free radical quenching and T4 ligase ligation. The pseudo Michaelis-Menten kinetic parameters k(cat) = 5.44 x 10(-2) h(-1) and K-M = 6.23 x 10(-3) M for complex 3 were obtained. Complex 3 also shows an enormous enhancement of the cleavage rate, of 1.5 x 10(6), in comparison to the uncatalysed hydrolysis rate (k = 3.6 x 10(-8) h(-1)) of ds-DNA.

Item Type:	Journal Article
Publication:	RSC ADVANCES
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	Copyright for this article belongs to Royal Society of Chemistry
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	26 Jun 2012 10:29
Last Modified:	28 Jun 2012 08:56
URI:	http://eprints.iisc.ac.in/id/eprint/44750

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