[Relation between the magnitude of biopolymer denaturation enthalpy and the low-temperature heat capacity of macromolecules in the "spiral" and "globular" states].

Thermodynamic values are analysed which characterize helix--coil transition in biopolymers in a wide temperature range. Conformation transition of fibrillar protein collagen is considered. The value delta gamma = integral of delta Cp . dT is determined (where delta Cp = Cp] kl--[Cp] sp is difference of collagen heat capacities in helix and coil states) for hydrated and dehydrated collagens within the temperature range 0 K divided by T dK (denaturation temperature). It is shown that hypothetic denaturation enthalpy of collagen at 0 K (delta H0 = delta Ht--delta gamma, where delta H--denaturation entalpy at the temperature Td) is well above the entalpy value calculated according to collagen models with one and two hydrogen bonds per tripeptide chain. The data point to a substantial contribution of water to stabilization of triple helix of collagen. The approach suggested may be used for checking the validity of Nernst theorem for highly anisotropic polymeric structures of biological origin.