Measurement of thermodynamic quantities in the heating-rate dependent thermal transitions of sequenced polytripeptides

The apparent excess heat capacities (Cp) of sequenced polytripeptides, (Pro-Pro-Gly)10 and (Pro-Hyp-Gly)10 in various solutions were measured using a differential scanning calorimeter. The dependence of the peaks of the Cp curves on heating rates was identical for all solutions studied. The apparent enthalpy changes of the transition did not depend on the heating rate. The equilibrium thermodynamic data, ΔH and ΔS of the transition, obtained calorimetrically in this system, are found to be linear to each other, indicating an enthalpy–entropy compensation. These results are discussed in terms of the phase transition.