Thermochimica Acta, Vol.290, No.1, 65-71, 1997
Heat-Capacity Peculiarities of DNA at Low-Temperatures (2-25 K)
This study deals with the low-temperature heat capacity (2-30 K) of DNA native fibres measured at different moisture contents with respect to the specificity of DNA hydration caused by its chemical composition (GC contents). Some peculiarities have been found for the heat capacity dependence of DNA on temperature (C-p = f(T)) at 2-4 K (the maximum heat capacity). The C-p for DNA reflects the redundant low-energy density of vibrational states (DVS) contributions as well as the ordinary Debye contribution. It was concluded that whereas the peculiarities of the DNA heat capacity at very low energy, below, 1 K, are well explained by the common two-level tunnelling system (TLS) model, the nature of the redundant DVS at 3-10 K is connected with the location of the vibration on the heterogeneous parts of the structure; these areas in the hydrated fibres of DNA may represent clusters of hydrate water "grown" on DNA matrix with a specific size of 1-2 nm.