On the possibility of true phase transition in heterogeneous DNA during thermal denaturation under conditions close to equal stability of A+T and G+C pairs
| Autor: | Galina O. Gladchenko, Yu. P. Blagoi, V. L. Galkin, Victor A. Sorokin, V. A. Valkeev, S. A. Khomenko |
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| Rok vydání: | 1979 |
| Předmět: |
Phase transition
Adenosine Guanine Hot Temperature Chemical Phenomena Biophysics chemistry.chemical_element Ionic bonding Thermodynamics Manganese Nucleic Acid Denaturation Biochemistry Ion Biomaterials Cytosine chemistry.chemical_compound Animals Base Composition Quantitative Biology::Biomolecules Chemistry Physical Chemistry digestive oral and skin physiology Organic Chemistry DNA General Medicine Helicity Crystallography Helix Nucleic Acid Conformation Cattle Derivative (chemistry) Thymidine |
| Zdroj: | Biopolymers. 18:2279-2287 |
| ISSN: | 1097-0282 0006-3525 |
| DOI: | 10.1002/bip.1979.360180915 |
| Popis: | The DNA helix–coil transition has been studied in the presence of high concentrations of manganese ions (about 10−3M), which corresponds to the conditions close to equal stability of the A+T and G+C pairs, at the ionic strengths of 10−1, 10−2, and 1.6 × 10−3M Na+. With the Mn2+ ion effect, the transition range is significantly reduced to not more than 0.2°C at 1.2 × 10−3M Mn2+ and 1.6 × 10−3M Na+. The melting curves display a sharp kink at the end of the helix–coil transition, which is interpreted as an indication of the second-order phase transition. It is shown that the melting curves obtained can be approximated by a simple analytical expression 1 – θ = exp[–a(tc - t)], where θ is the DNA helix fraction, tc is the phase transition temperature, and a is an empirical parameter characterizing the breadth of the melting range and responsible for the magnitude of a jump of the helicity derivative with respect to the temperature at the phase transition point. |
| Databáze: | OpenAIRE |
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