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+,Ni2+,Mn2+ ions with deoxyribonucleotides of canonic bases (dGMP,dAM P,dCMP,dTMP) and native DNA. Heteroatoms of the bases, coordinating io ns, and binding constants which characterize the formation of metal co mplexes are found. The affinity of the ions is lower for the deoxyribo nucleotide 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 Cu2 ions, Ni2+ and Mn2+ ions do not interact with N3C both in monomers an d polymers. This seems to be the main factor explaining why copper mak es 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 x 10(-2) M.