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

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 meas...

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Bibliographic Details
Published in:International journal of biological macromolecules 2003-12, Vol.33 (4-5), p.183-191
Main Authors: Zozulya, V N, Nesterov, A B, Ryazanova, O A, Blagoi, Yu P
Format: Article
Language:English
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
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Summary: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.
ISSN:0141-8130
1879-0003
DOI:10.1016/j.ijbiomac.2003.08.003