کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9890935 | 1540342 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Mg2+ and Ni2+ ion effect on stability and structure of triple poly I·poly A·poly I helix
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
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چکیده انگلیسی
The effects of Mg2+ and Ni2+ ions on the absorption spectra of IMP, single-stranded poly I and three-stranded A2I in solutions with 0.1 M Na+ (pH 7) have been studied. In contrast to Mg2+ ions, the Ni2+ ions affect the absorption spectra of these polynucleotides and IMP. The concentration dependences of the intensity at the extrema in the differential UV spectra suggest that in the region of high Ni2+ concentrations ionic complexes with poly I and A2I are formed, which are characterized by the association constants Kâ´I=2000Mâ1 and Kâ´A2I=550Mâ1, respectively. The shape of the DUV spectra prompts the conclusion that these complexes are formed due to the inner-sphere interaction of Ni2+ ions with N7 of poly I and A2I presumably due to the outer-sphere Ni2+-O6 interaction. The formation of the complexes leads to destruction of A2I triplexes. The dependences of the melting temperature (Tm) of A2I on Mg2+ and Ni2+ concentrations have been measured. The thermal stability is observed to increase at the ionic contents up to 0.01 M Mg2+ and only to 2 Ã 10â4 M Ni2+. At higher contents of Ni2+ ions, Tm lowers and the cooperativity of A2I melting decreases continuously. In all the cases the melting process is the A2I â A + I + I (3 â 1) transition. According to the “ligand” theory, these effects are generated by the energy-advantageous Ni2+ binding to single-stranded poly I (Kâ´A2I
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Biological Macromolecules - Volume 35, Issues 3â4, April 2005, Pages 201-210
Journal: International Journal of Biological Macromolecules - Volume 35, Issues 3â4, April 2005, Pages 201-210
نویسندگان
V.A. Sorokin, V.A. Valeev, G.O. Gladchenko, M.V. Degtyar, E.A. Andrus, V.A. Karachevtsev, Yu.P. Blagoi,