An FTIR spectroscopic study of calf-thymus DNA complexation with Al(III) and Ga(III) cations.
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.
Ahmad
R
R
Departement Chimie-Biologie, Université du Québec à Trois-Rivières, Canada.
Naoui
M
M
Neault
J F
JF
Diamantoglou
S
S
Tajmir-Riahi
H A
HA
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
D002412:Cations; D003854:Deoxyribonucleotides; D010710:Phosphates; D006147:Guanine; D004247:DNA; D005708:Gallium; D000535:Aluminum