Effect of Ni2+ and Cd2+ ions on thermally induced conformational transitions in poly(dA)-poly(dT) system

Abstract

Effects of Ni(2+) and Cd(2+) ions on thermally induced conformational transitions in the poly(dA)·poly(dT) polynucleotide duplex and poly(dA)·2poly(dT) triplex under near physiological ionic conditions were studied by measurement of UV absorption melting curves and static light scattering intensity. The diagrams of conformational transitions in poly(dA)-poly(dT)-Me(2+) systems were plotted. An aggregation in these polynucleotide systems arises at certain values of the metal ions concentration and the temperature after the polymer dissociation into single strands. The phenomenon is conditioned by the aggregation of poly(dA) via the interstrand cross-linking by the dication bridges. Unlike Ni(2+), Cd(2+) induces formation of very stable aggregates which did not disintegrate even upon cooling up to room temperature.

Single Molecular Chelation Dynamics Reveals That DNA Has a Stronger Affinity toward Lead(II) than Cadmium(II)

“…Alkaline-earth metal ions, such as Mg 2+ and Ca 2+ , bind mainly on the phosphate groups of DNA due to electrostatic interactions, and thus stabilize the DNA helix structure. In contrast, for transition metal ions, such as Cd 2+ and Cu 2+ , both phosphate groups and DNA bases are the favored binding sites. − At low metal/phosphate ratios, the majority of the binding is on the phosphates. At high metal ion concentrations, specific binding on DNA bases dominates.…”