Thermodynamic parameters of stabilization of the Yersinia pestis Caf113-149 subunit in compact form

Several experimental methods (circular dichroism, viscosity, intrinsic fluorescence, and fluorescence labeling) were used to study the conformational folding/unfolding transitions in a compact monomeric form of the Caf1 13-149 subunit under the action of guanidine hydrochloride in the temperature range 5–45°C. It has been shown that transitions always occur between two major states (unfolded and compact). This has made it possible to determine all the main thermodynamic functions that characterize the compact state of the Caf1 13-149 subunit: stability temperature T m , free energy of stabilization Δ G st , enthalpy Δ H tr , and heat capacity jump Δ C in collapse of the structure. These data have been confirmed by an independent experiment on melting of fluorescently labeled protein.