Interaction of divalent metal ions with poly(riboinosinic acid)

Abstract

Methods of differential UV and visible spectroscopy are used to study the interaction of Mg2+, Ca2+, Mn2+ and Cu2+ ions with four (4×I)‐ and single‐stranded poly I in solutions with 1 mol·l–1 Na+. Up to concentrations of about 0.1 mol·l–1 Mt2+, Mg2+ and Ca2+ ions do not bind to heteroatoms of hypoxanthine of 4×I. Cu2+ ions interact with N7 and/or N1 and possibly with O6 through the water molecule of the hydrate shell of the ion. It is likely that the interaction with O6 causes enolization of the hypoxanthine, N1 deprotonation and, as a result, this leads to the melting of the four‐stranded helix. In single‐stranded chains, Cu2+ ions induce the formation of compact particles which have the effective radii re ≈ 100 Å. The Mn2+‐induced differential spectra are similar to those observed in the presence of Cu2+ ions but in the case of Mn2+ they occur at concentrations about two orders of magnitude higher. In contrast to the positive cooperativity of the Cu2+ binding to bases of single‐stranded poly I, their interaction with 4×I has the negative cooperativity.

Nanoconstructions based on double-stranded nucleic acids

“…Such a decrease of ability of NaC to regenerate the initial structure reflects the perturbation of the DNA secondary structure. This is consistent with the results above on possible interaction of Cu 2+ ions with initial NA molecules during the heating [35][36][37]. This interaction is accompanied by a distortion of the parameters of the DNA secondary structure and this makes impossible the cholesteric ordering of a somodified, neighboring DNA molecules.…”

Divalent metal ion effect on helix–coil transition of high molecular weight DNA in neutral and alkaline solutions

“…Considering that the order of magnitude for the radius of gyration of the statistical single-stranded coil is 10 3Å [29], this means that Mg 2+ ions induce the transition of single-stranded melted DNA parts into the compact form. The formation of similar compact particles by single-stranded poly(rA) and poly(rI) in the presence of Ca 2+ , Ni 2+ and Cu 2+ was observed earlier also in neutral solutions [26,30,31]. Fig.…”

DNA structural transitions induced by divalent metal ions in aqueous solutions

“…When estimating the particle dimensions we assumed that the particle shape is close to spherical. More detailed method of estimation of the scattering particles size is described in [26].…”