Denaturation Kinetics of Biopolymers by Differential Thermal Analysis

Abstract

SEVERAL workers have described equations to calculate the activation energy of a reaction from the exothermic or endothermic peaks which occur during a differential thermal analysis (DTA) experiment^1–3. There is a second type of differential thermal analysis curve, one not characterized by a maximum or a minimum but by a sigmoid shape caused by a change in the heat capacity of the system during the experiment. Fig. 1 shows an idealized sigmoid type isotherm. Such curves are well known in polymer chemistry, where they indicate the occurrence of a so-called second order phase transition in the solid polymer. We report here the observation of such thermograms for aqueous solutions of several biopolymers including proteins and nucleic acid, and direct attention to the possibility of obtaining kinetic data from them.