Measurement of Dynamic Specific Heat Capacity of Lysozyme Crystals

Abstract

We measured the dynamic heat capacity of lysozyme crystals near the heat denaturation temperature. By means of ac calorimetry technique at a frequency of 1.7 Hz, it was found that the maximum value of their heat capacity was much smaller than that measured by usual dc calorimetry methods. There was no appreciable difference in the dynamic heat capacities between on cooling and on heating. The specific heat capacity of lysozyme crystals with the form A at a constant pressure was obtained to be 0.418 ±0.104 cal g -1 K -1 at 296 K. The following values are given for the enthalpy and the entropy at the heat denaturation process associated with the higher response than 1.7 Hz. Δ H =3.65 ±1.32 kcal mol -1 and Δ S =8.24 ±3.15 cal mol -1 K -1 .