Thermodynamic study of interaction between phthalocyanines with calf thymus DNA

Subject Areas : Journal of Physical & Theoretical Chemistry

M. Aghaie ¹ , F. Naderi ² , M. Monajjemi ³ , H. Aghaie ⁴ , N. Safari ⁵ , P.R. Jamaat ⁶

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Received: 2015-05-03 Accepted : 2015-05-03 Published : 2007-02-01

Keywords: DNA, Phthalocyanine, SQUAD, Formation constant,

Abstract :

The experimental determination of formation constant for interaction of two water soluble phthalocyanines,Cobalt (II) 4,4',4",4'"-tetrasulpho phthalocyanine (CoTsPc ) and Manganese(II) 4,4',4",4"-tetrasulphophthalocyanine (MnTsPc ) , with calf thymus DNA have been studied by UV-Vis spectrophotometric methodat lrnM phosphate buffer , pH 7.4 and at 5 different temperatures 20,25,30,35 and 400CC . The changes of Uv-Vis absorption spectra during the titration of these phthalocyanines with calf thymus DNA revealed a largehypochromicity (up to 45%) of the phthalocyanines maximum bands, usually considered as proof ofphthalocyanine intercalation in to DNA. The calculated formation constants, Ks , according to theSQUAD software were in the range of 104-105 M-1.By using the Van't Hoff equation. The values of enthalpyand entropy changes associated to the (CoTsPc +DNA) and(MnTsPc+DNA) were determined .Then by using AG°=-RTLIIK, we calculated the values of AG° at consideredtemperatures. Our results showed strong electrolytic effects on phthalocyanines behavior and increasingNaCl concentration induced self-aggregation of the CoTsPc and MnTsPc.