Differential thermal analysis of protein denaturation in solution

Differential thermal analysis (DTA) has been shown to be useful for the study of the denaturation of proteins in solution. Each protein examined produced an endotherm of characteristic shape and temperature of peak minimum. Fine structure was observed in the thermogram for muramidase denaturation, and was shown to be dependent upon both protein concentration and scan rate. In a series of eight repeated runs with muramidase, the standard error for the determination of peak areas was 2.6%. Since the enthalpy of transition can be obtained from the area under the peak if a suitable standard is used, DTA shows promise as a rapid and reasonably accurate method for obtaining heats of denaturation. The reproducibility of peak minima, with standard error of 0.11 °C, may make DTA a sensitive tool for detecting minor changes in protein conformation. Kinetic parameters can also be obtained from DTA data. It is anticipated that the method will give information on the state of proteins in complex biological systems.