HEAT-CAPACITY OF NATIVE DNA STRANDS AT TE MPERATURES 2-25 K

The data on low-temperature heat capacity (2-25 K) of native DNA stran ds at different humidities are presented, which take into account the specificity of hydration of DNA due to its chemical composition (GC-co ntent). The temperature dependence of DNA heat capacity (C-p=f(T)) at 2-4 K was analyzed. Analysis of C-p=f(T) involves both the ordinary De bay density and excessive low-energy density of oscillatory states (DO S) peculiar to noncrystalline solids. It is concluded that heat capaci ty of DNA at very energies (less than 1 K) is well described in terms of the generally accepted model of two-level systems. The nature of ex cessive DOS at energies 3-10 K is related to oscillatory excitations o n structural inhomogeneities, which can represent clusters of hydrate water molecules (similar to 1-2 nm) <<grown>> in DNA matrix.