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| Titel: |
Phase diagram of Ni2+ ions complexes with polyU×polyA×polyU |
| Auteur: |
Sorokin V. A. Valeev V. A. Usenko E. L. |
| Verschenen in: |
Biopolymers and cell |
| Paginering: | Jaargang 25 (2009) nr. 3 pagina's 218-225 |
| Jaar: |
2009 |
| Inhoud: |
Aim. To investigate Ni2+ ion effect on the conformational equilibrium of the three-stranded polynucleotide polyU×polyA×polyU and to ascertain thermodynamic parameters of the metal complex formation. Methods. The differential UV spectroscopy and thermal denaturation. Results. Dependences of conformational transition (Tm) of poly U×polyA×polyU (A2U) on Ni2+ ion con- centration (up to 0.001 M) under conditions close to physiological ones (0.1 M Na+, pH 7) were obtained. At [Ni2+] < 3×10–4 M two branches are observed in the phase diagram, corresponding to A2U → polyA×polyU (AU) + polyU (3→2) and AU→polyA + polyU (2→1) transitions. Only A2U→polyU + polyA + polyU (3→1) transition is realized at higher Ni2+ concentrations and upon A2U heating. Effective binding constants are determined for Ni2+ ions with AU (850 M–1) and A2U (1300 M–1) as well as 3→2 transition enthalpy (DH3→2 = 4±1 kcal/mol×triplet). Conclusions. By the equilibrium binding theory the thermodynamic nature of (Tm)2→3 different behavior in the phase diagram of AU in the presence of Mg2+ and Ni2+ ions was determined. A larger difference of the magnesium affinity to A2U and AU as compared with that to AU and poly A results in (Tm)2→3 decrease whereas the opposite ratio of Ni2+ ion binding constants induces its increasing |
| Uitgever: |
Institute of molecular biology and genetics, National Academy of Sciences of Ukraine (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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