Thermal Denaturation of Proteins Studied by UV Spectroscopy

UV spectroscopy has been widely used for monitoring the unfolding of proteins. During temperature-induced denaturation the protein absorbance changes with temperature until the process of unfolding is completed. Analysis of the measured absorbance-vs-temperature curve (UV melting curve) based on the two-state approximation of the denaturation process leads to the van't Hoff enthalpy of denaturation at the temperature of the half-transition, DH°(T d), and the corresponding entropy of denaturation, DS°(T d). A determination of DH°(T d) and DS°(T d) for a-chymotrypsinogen A at pH 3.0 from the experimental UV melting curve is demonstrated.