title: Interaction of Z form poly(dG-dC).poly(dG-dC) with divalent metal ions: localization of the binding sites by I.R. spectroscopy.
abstract: The secondary structures of poly(dG-dC).poly(dG-dC) in the presence of alcaline , alcaline earth and first row transition metal ions (Na+, Mg2+, Co2+, Ni2+) are investigated by infrared spectroscopy. The conformational transitions are studied as a function of the hydration of the polynucleotide and counter-ion nature and content. The use of selectively deuterated poly(dG-dC).poly(dG-dC) on the 8-carbon of guanines allows to show that a direct interaction occurs between the N7 site of guanines and the transition metal ions Co2+ and Ni2+. In the case of Mg2+, for high ion/nucleotide ratios, the interaction occurs essentially at the level of the phosphate groups. This interaction leads to a modification of the left-handed conformation. Based on the IR spectroscopy results, an explanation is proposed for the different efficiencies of these various ions to induce the B----Z transition.
mesh_terms: D002413:Cations, Divalent; D003035:Cobalt; D008274:Magnesium; D009532:Nickel; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D012964:Sodium; D013055:Spectrophotometry, Infrared / Q000379:methods
chemical_list: D002413:Cations, Divalent; D011089:Polydeoxyribonucleotides; C019530:poly(dC-dG); D003035:Cobalt; D009532:Nickel; D012964:Sodium; D008274:Magnesium