Thermal denaturation of α-chymotrypsinogen A in presence of polyols at pH 2.0 and pH 3.0

Osmolytes are cosolutes that induce stabilization of the structure of proteins. Polyols are osmolytes that have importance in a wide variety of biotechnological and industrial processes. In this work, a systematic study concerning the effect of polyols of different number of methylene and hydroxyl groups on the stability of α-chymotrypsinogen A is presented. Protein thermal stability measurements in buffer, ethylene glycol, glycerol, meso-erythritol, sorbitol and inositol was followed by fluorescence measurements. Under the selected conditions, the thermal denaturation of α-chymotrypsinogen A is a reversible transition between native and unfolded state that can be well described by a two-state model. Reversibility of the transition was confirmed by DSC, circular dichroism, UV–Vis and fluorescence measurements. The change in thermal stability of the protein in the presence of ethylene glycol, glycerol, erythritol, sorbitol and inositol shows that ethylene glycol is the only polyol that presents a destabilizing effect. The other cosolutes exert stabilizing effects that increase with the number of hydroxyl groups and depend on concentration.