Book of Abstracts: Albany 2003
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
1Department of Chemistry-Biology