Heat-induced conformational transition of cytochrome c observed by temperature gradient gel electrophoresis at acidic pH

Temperature-gradient gel electrophoresis (TGGE) has been used to study the thermal unfolding of ferricytochrome c in low and high concentrations of ac etic acid. It has been observed that the mobility of cytochrome c is a line ar function of temperature when the system is characterized by a homogeneou s population of conformation-state, single molecular species. Within the tr ansition temperature range, the mobility clearly displays the characteristi c sigmoidal shape describing the transitions of protein unfolding. The data obtained by TGGE were used to estimate the apparent thermodynamic paramete rs (enthalpy change Delta H-vh and transition temperature T-m), associated with the transition of unfolding. The accuracy of the apparent thermodynami c parameters obtained by this method agrees within error limits with the va lues obtained by direct calorimetric measurements using differential scanni ng calorimetry (DSC).