| Popis: |
This study investigates the effect of electrolytes on the thermodynamic stability of the protein α-chymotrypsinogen A at acid pH. Protein thermal stability in water, buffers and aqueous solutions of (NH4)2SO4, NH4NO3, NaCl, KCl at pH 2.00, 3.00 and 3.50 was followed by ultraviolet-visible spectroscopy (UV-VIS) and differential scanning calorimetry (DSC). Thermodynamic parameters of denaturation of the protein in water and in the aqueous mixed solvents were obtained from thermal denaturation curves. The results suggest that the unfolding process is reversible process and is well represented by a two state model. All the electrolytes used in this study increase the conformational stability of the protein. The stabilising effect of the electrolytes used in this study increases with electrolyte concentration and is in accordance with the effect of anions and cations described for positively charged proteins, being ammonium sulphate the salt that exerts the largest stabilising effect on α-chymotrypsinogen A. |
