Different modes of DNA cleavage activity of dihydroxo-bridged dicopper(II) complexes having phenanthroline bases

Thomas, Anitha M and Nethaji, Munirathinam and Chakravarty, Akhil R (2004) Different modes of DNA cleavage activity of dihydroxo-bridged dicopper(II) complexes having phenanthroline bases. In: Journal of Inorganic Biochemistry, 98 (6). pp. 1087-1094.

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Abstract

Dihydroxo-bridged dicopper(II) complexes $[{\lbrace}Cu(phen){\rbrace}_2(\mu-OH)_2](ClO_4)_2 (1), [{\lbrace}Cu(dpq){\rbrace}_2$ $(\mu-OH)_2](ClO_4)_2 (2)$ and $[{\lbrace}Cu(dppz)- (DMF){\rbrace}_2(\mu-OH)_2](PF_6)_2 (3),$ where phen, dpq and dppz are 1,10-phenanthroline, dipyridoquinoxaline and dipyridophenazine, respectively, are prepared and their DNA binding and cleavage properties studied. Complex 3 has been structurally characterized by X-ray crystallography. The complexes have a ${\lbrace}Cu_2(\mu-OH)_2{\rbrace}^{2+}$ core with an essentially planar arrangement of two $CuN_2O_2$ basal planes. The complexes are avid binder to calf thymus DNA (Kapp value of $4.8X10^6$ and $5.9X10^6 M^{-1}$ for 2 and 3, respectively, from ethidium displacement assay) and exhibits significant cleavage of supercoiled (SC) pUC19 DNA in dark in presence of mercaptopropionic acid. Besides, the dpq and dppz complexes display photo-induced DNA cleavage on UV (312 nm) and red light (632.8 nm) irradiations in absence of any additives. Mechanistic investigations reveal minor groove binding for the phen and dpq complexes, and major groove preference for the dppz species. The oxidative DNA cleavage reactions in presence of mercaptopropionic acid as a reducing agent involve hydroxyl radicals. The photo-cleavage reactions at UV light involve singlet oxygen as the reactive species, while similar reactions on red light irradiation (632.8 nm) proceed through the formation of hydroxyl radical. The complexes show significant DNA hydrolase activity in absence of any additives under dark reaction conditions.

Item Type:	Journal Article
Publication:	Journal of Inorganic Biochemistry
Publisher:	Elsevier
Additional Information:	The copyright belongs to Elsevier.
Keywords:	Dicopper(II) complexes;Phenanthroline bases;DNA cleavage;Crystal structure;Groove selectivity
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	10 May 2006
Last Modified:	19 Sep 2010 04:26
URI:	http://eprints.iisc.ac.in/id/eprint/6606

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