title: Conformational transitions and aggregation in poly(dA)-poly(dT) system induced by Na+ and Mg2+ ions.
abstract: Effects of Mg(2+) ions on thermally induced conformational transitions in the synthetic poly(dA).poly(dT) and poly(dA).2poly(dT) were studied in the buffered solutions (pH 6.9), containing 0.1 or 1M NaCl at polynucleotide concentration of 0.1-0.3mM (in nucleic bases). The experiments consist of measurements of the UV absorption and intensity of conventional visible static light scattering. The diagram of conformational transitions in the poly(dA)-poly(dT)-Mg(2+) system was constructed on a basis of experimental data obtained. Anomalously strong light scattering, like critical opalescence, has been revealed at 0.1M NaCl and [Mg(2+)]>/=20mM in the melting range of both polynucleotides, which eventually disappeared after the completion of polymer strands separation. The effect presumably is caused by a fluctuation process of polymer strands complexing which arises at a certain concentration of Mg(2+) ions.
authors: Institute for Low Temperature Physics and Engineering of National Academy of Sciences of Ukraine, 47 Lenin Ave., 61103 Kharkov, Ukraine. zozulya@ilt.kharkov.ua
authors: V N
authors: VN
authors: Zozulya
authors: A B
authors: AB
authors: Nesterov
authors: O A
authors: OA
authors: Ryazanova
authors: Yu P
authors: YP
authors: Blagoi
mesh_terms: D007477:Ions; D008274:Magnesium / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry; D011061:Poly A / Q000737:chemistry*; D011071:Poly T / Q000737:chemistry*; D011067:Poly dA-dT / Q000737:chemistry; D012964:Sodium / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013816:Thermodynamics
chemical_list: D007477:Ions; D009692:Nucleic Acid Heteroduplexes; D012996:Solutions; D011061:Poly A; D011071:Poly T; C015465:poly(dA); D011067:Poly dA-dT; D012965:Sodium Chloride; D012964:Sodium; D008274:Magnesium