title: 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.
authors.affiliation: Departement Chimie-Biologie, Université du Québec à Trois-Rivières, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Ahmad
authors.forename: M
authors.initials: M
authors.lastname: Naoui
authors.forename: J F
authors.initials: JF
authors.lastname: Neault
authors.forename: S
authors.initials: S
authors.lastname: Diamantoglou
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D000818:Animals; D002412:Cations / Q000737:chemistry*; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D003854:Deoxyribonucleotides / Q000737:chemistry; D005708:Gallium / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013950:Thymus Gland
chemical_list: D002412:Cations; D003854:Deoxyribonucleotides; D010710:Phosphates; D006147:Guanine; D004247:DNA; D005708:Gallium; D000535:Aluminum