[Thermodynamic parameters of stabilization in a compact form of the Caf1(13-149) subunit from Yersinia pestis]

With a number of experimental methods (circular dichroism, viscosity, intrinsic fluorescence and fluorescence labelling) the conformational folding-unfolding transitions in a compact monomeric form of the Caf1(13-149) subunit were studied under the action of guanidine hydrochloride in the temperature range from 5 to 45 degrees C. It has been shown that transitions always occur between two major states (unfolded and compact). It has made it possible to determine all main thermodynamic functions that characterize the compact state of the Caf1(13-149) subunit: temperature stability T(m), the free energy of stabilization deltaG(st), enthalpy deltaH(tr) and heat capacity jump deltaC collapse of the structure. Data obtained have been confirmed by an independent experiment on melting of fluorescently labeled proteins.