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Thermodynamic Study of Interaction of TSPP, CoTsPc, and FeTsPc with Calf Thymus DNA

M. Monajjemi1*, H. Aghaie1, and F. Naderi1,2

1Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran, Iran; fax: (98)21-44804172; E-mail: m_monajjemi@yahoo.com

2Shahriyar-Shahr e Ghods Branch, Islamic Azad University, Tehran, Iran

* To whom correspondence should be addressed.

Received November 8, 2006; Revision received December 29, 2006
The interaction of two water soluble phthalocyanines, cobalt(II) 4,4´,4´´,4´´´-tetrasulfo-phthalocyanine (CoTsPc) and iron(II) 4,4´,4´´,4´´´-tetrasulfo-phthalocyanine (FeTsPc), and one water soluble porphyrin, tetra sodium meso-tetrakis(p-sulfophenyl)porphyrin (TSPP), with calf thymus DNA has been studied by UV-Vis spectroscopy at five different temperatures (20, 25, 30, 35, and 40°C). The optical absorption spectra of these materials were analyzed to obtain binding constants and stoichiometries using SQUAD software. The results show that the best fitting corresponds to a 1 : 1 complex model between a base pair of DNA and these materials. All of the studied porphyrin and phthalocyanines showed strong electrolyte effect, and increasing NaCl concentration induced self-aggregation of these materials.
KEY WORDS: DNA, porphyrin, phthalocyanine, SQUAD

DOI: 10.1134/S0006297907060089