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[The nature of different influence of Cd2+ ions on the conformation of three-stranded polyU-polyA-polyU and polyI-polyA-polyI in aqueous solution].
- Source :
-
Biofizika [Biofizika] 2007 Nov-Dec; Vol. 52 (6), pp. 1017-29. - Publication Year :
- 2007
-
Abstract
- The methods of UV (DUV) spectroscopy and thermal denaturation were used to study the effect of Cd2+ ions on the conformational equilibrium of three-stranded (A21, A2U) and single-stranded (poly U, poly A and poly I) polynucleotides in aqueous solutions containing 0.1 M Na+ (pH 7). An analysis of the form and intensities of DUV-spectra of poly A, poly I and A2I revealed the presence of two types of complexes: interaction with N7 of purines, resulting in the formation of macrochelates and binding to N1 of poly A and poly I. Cd2+ ions do not bind to heteroatoms of A2U nitrogen bases, and, therefore, the conformation of its structure remains unchanged up to a concentration of Cd2+ 0.01 M. A "critical" concentration (1.5x10(-4) M) of Cd2+ ions exists above which A2I transits cooperatively into a new helical conformation, which has a lower thermostability. It is supposed that, during the formation of metallized A2I, Cd2+ ions form bridges between the adenine and hypoxanthine of its homopolynucleotide circuits, being arranged inside the triple helix.
Details
- Language :
- Russian
- ISSN :
- 0006-3029
- Volume :
- 52
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Biofizika
- Publication Type :
- Academic Journal
- Accession number :
- 18225653