Thermodynamic parameters of stabilization of the Yersinia pestis Caf1 sub(13-149) 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 sub(13-149) subunit under the action of guanidine hydrochloride in the temperature range 5-45 degree 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 sub(13-149) subunit: stability temperature T sub(m), free energy of stabilization Delta G sub(st), enthalpy Delta H sub(tr), and heat capacity jump Delta C in collapse of the structure. These data have been confirmed by an independent experiment on melting of fluorescently labeled protein.