Conformational transitions and aggregation in poly(dA)-poly(dT) system induced by Na+ and Mg2+ ions

• Published in: International journal of biological macromolecules Vol. 33; no. 4-5; pp. 183 - 191
• Main Authors: Zozulya, V N, Nesterov, A B, Ryazanova, O A, Blagoi, Yu P
• Format: Journal Article
• Language: English
• Published: Netherlands 01.12.2003
• Subjects: Ions; Magnesium - chemistry; Nucleic Acid Conformation; Nucleic Acid Heteroduplexes - chemistry; Poly A - chemistry; Poly dA-dT - chemistry; Poly T - chemistry; Sodium - chemistry; Sodium Chloride - chemistry; Solutions; Spectrophotometry, Ultraviolet; Temperature; Thermodynamics
• ISSN: 0141-8130
• DOI: 10.1016/j.ijbiomac.2003.08.003

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.