title: Thallium-DNA complexes in aqueous solution. Major or minor groove binding.
abstract: Thallium (Tl) binds to the major and minor grooves of B-DNA in the solid state (Howerton et al., Biochemistry 40, 10023-10031, 2001). The aim of this study was to examine 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. Direct Tl bindings to guanine and thymine were evident by major spectral changes of DNA bases with overall binding constant of K = 1.40 x 10(4) M(-1) and little perturbations of the backbone phosphate group. Both major and minor groove bindings were observed with no alteration of the B-DNA conformation. At low metal concentration (0.5 mM), the number of cations bound were 10 per 1000 nucleotides, while at higher cation concentration (10 mM), this increased to 30 cations per 1000 nucleotides.
authors.affiliation: Department of Chemistry-Biology, University of Quebec at Trois-Rivieres, C.P. 500, TR, Quebec, Canada G9A 5H7.
authors.forename: A Ahmed
authors.initials: AA
authors.lastname: Ouameur
authors.forename: Sh
authors.initials: Sh
authors.lastname: Nafisi
authors.forename: N
authors.initials: N
authors.lastname: Mohajerani
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D009994:Osmolar Concentration; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013793:Thallium / Q000378:metabolism / Q000494:pharmacology*; D013950:Thymus Gland; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; D004247:DNA; D013793:Thallium