An FTIR spectroscopic study of calf-thymus DNA complexation with Al(III) and Ga(III) cations.
ABSTRACT The interaction of calf-thymus DNA with trivalent Al and Ga cations, in aqueous solution at pH = 6-7 with cation/DNA(P) (P = phosphate) molar ratios (r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2 was characterized by Fourier Transform infrared (FTIR) difference spectroscopy. Spectroscopic results show the formation of several types of cation-DNA complexes. At low metal ion concentration (r = 1/80, 1/40), both cations bind mainly to the backbone PO2 group and the guanine N-7 site of the G-C base pairs (chelation). Evidence for cation chelate formation comes from major shifting and intensity increase of the phosphate antisymmetric stretch at 1222 cm-1 and the mainly guanine band at 1717 cm-1. The perturbations of A-T base pairs occur at high cation concentration with major helix destabilization. Evidence for cation binding to A-T bases comes from major spectral changes of the bands at 1663 and 1609 cm-1 related mainly to the thymine and adenine in-plane vibrations. A major reduction of the B-DNA structure occurs in favor of A-DNA upon trivalent cation coordination.
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ABSTRACT: Note: This article was originally published with an incorrect version of the Acknowledgments, which appeared on p. 218 of the print version. The correct version of the Acknowledgments appeared on pp. 1–2. The corrected article is available below.Journal of Toxicology and Environmental Health Part B 02/2007; 10 Suppl 1:1-269. · 4.72 Impact Factor