[Heat capacity of native DNA fibers at 2-25 K].

The data on low-temperature heat capacity (2-25 K) of native DNA strands at different humidities are presented, which take into account the specificity of hydration of DNA due to its chemical composition (GC-content). The temperature dependence of DNA heat capacity (Cp = f(T)) at 2-4 K was analyzed. Analysis of Cp = f(T) involves both the ordinary Debay density and excessive low-energy density of oscillatory states (DOS) peculiar to noncrystalline solids.

[Low-temperature heat capacity of DNA in various conformation states].

Experimental results are presented on temperature--dependent DNA heat capacity in three different states: a) intact--native DNA in the conformation of double helix, b) disordered conformation of polynucleotide chains in the state of statistical coils, c) completely "degenerated" polynucleotide chains--mechanical mixture of nucleotides. Data on heat capacity (4-400 K) at different water content in the specimens allow a definition of relative changes in the pattern of the entropy temperature dependence for these conformational states with the account for the structural effect of water.

[Heat-capacity of DNA at low temperatures and varying humidities].

Adiabatic low temperature microcalorimeter working in a wide temperature range, including that of liquid helium, is described. Heat capacity of DNA at various water concentrations was measured at 4-400 degrees K. It is shown that the pattern of its change is determined by the hydration parameter n (number of water molecules per mole of base pairs).

[Investigation of hydration of poly[d(A-T)] polynucleotide in helical and random coli states by the method of low temperature scanning microcalorimetry].

Thermodynamic parameters of the process of water phase transition in poly[d(A-T)] solutions in the wide range of polymer concentration have been studied. Curves of the heat capacity changes (delta Cp) depending on concentration of polymer and the temperature in the area of ice-water phase transition have been plotted. Thermodynamic parameters of the process of helix--random coli transition in water solutions of poly[d(A-T)] have been measured.

[Ribonuclease hydration and its heat stability in solutions of H2O and D2O].

Ribonuclease hydration in wide concentration and temperature range using differential scanning microcalorimetry and NMR technique was studied. The temperature- concentration equilibrium diagram for H2O--ribonuclease system was suggested. Protein hydration in D2O was shown to be higher than in ordinary water.