Interaction of bivalent copper, nickel, manganese ions with native DNA and its monomers

UV differential spectroscopy is applied to study the interaction of Cu 2+, Ni 2+, Mn 2+ ions with deoxyribonucleotides of canonic bases (dGMP, dAMP, dCMP, dTMP) and native DNA. Heteroatoms of the bases, coordinating ions, and binding constants which characterize the formation of metal complexes are found. The affinity of the ions is lower for the deoxyribonucleotide bases than for the ribonucleotide ones. This indicates that 02′ of ribose participates in the stabilization of the metal complex even under conditions close to the neutral one (pH 6). Unlike the Cu 2+ ions, Ni 2+ and Mn 2+ ions do not interact with N3C both in monomers and polymers. This seems to be the main factor explaining why copper makes DNA transform into a structure with a quasi-Hoogsteen pairing of GC pairs. No transformations of this kind or helix-coil transitions are caused by manganese and nickel up to concentrations 4 × 10 −2 M.