title: Left-handed helical structure of poly[d(A-C)].poly[d(G-T)] studied by infrared spectroscopy.
abstract: Infrared spectroscopic studies demonstrate the ability of poly[d(A-C)].poly[d(G-T)] to adopt a Z-type conformation. The Z form of the unmodified polynucleotide is induced by Ni2+ counterions and not by Na+. The B----Z equilibrium is shifted at room temperature, in the presence of 1 Ni2+/nucleotide, by an increase in the concentration of poly[d(A-C)].poly[d(G-T)]. The importance of specific binding of Ni2+ ions on the N7 site of purines in the stabilization of the Z form is also discussed.
mesh_terms: D002412:Cations; D009532:Nickel / Q000494:pharmacology; D009690:Nucleic Acid Conformation / Q000187:drug effects; D011089:Polydeoxyribonucleotides; D012964:Sodium / Q000494:pharmacology; D013055:Spectrophotometry, Infrared
chemical_list: D002412:Cations; D011089:Polydeoxyribonucleotides; C028333:poly(d(A-C).d(G-T)); D009532:Nickel; D012964:Sodium