Book of Abstracts: Albany 2003

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Conversation 13
Abstract Book
June 17-21 2003

Thallium(I) Binds to Major and Minor Grooves of DNA in Aqueous Solution

Tl(I) is not a biological cation but it has been shown to be a useful K(I) mimic. We report the binding of Tl(I) cation with calf-thymus DNA in aqueous solution at physiological pH, using constant concentration of DNA (12.5 mM) and various concentrations of metal ions (0.5 to 20 mM). UV-visible and FTIR spectroscopic methods were used to determine the cation binding site, the binding constant and DNA structural variations in aqueous solution. Solution study showed Tl bindings to guanine and adenine N-7 sites, thymine O-2 atom and the backbone PO2 group with overal binding constant of K = 1.40 × 104 M-1. Both major and minor groove cation bindings were recently reported in the crystal structure of Tl(I) with B-DNA complexes (1), which show similarities with our study in aqueous solution (2).

Preferential binding model proposed for Thallium (Tl)-DNA interaction. (A) Major groove; (B) Minor groove.

A. Ahmed Ouameur1
Sh. Nafisi2
N. Mohajerani2
H. A. Tajmir-Riahi1,*

1Department of Chemistry-Biology
University of Québec at Trois-Riviéres
C.P. 500, TR
Québec, Canada G9A 5H7
2Department of Chemistry
Azad University
Tehran Central Branch
Tehran, Iran

References and Footnotes
  1. S. B. Howerton, C. C. Sines, D. VanDerveer and L. D. Williams, Biochemistry 40, 10023-10031 (2002).
  2. A. Ahmed-Ouameur, Sh. Nafisi, N. Mohajerani and H. A. Tajmir-Riahi, J. Biomol. Struct. Dyn. In press (2003).