EFFECT OF HYDRATION ON THERMOSTABILITY OF SERINE ESTERASES

The thermostability of several serine esterases has been studied using differential scanning calorimetry. The denaturation temperature (Tm) was found to be 30-50 degrees C higher in anhydrous environments than in aqueous solution. An almost linear decrease in Tm as a function of water activity (A(w)) was observed. It is concluded that the highest p roductivity of an enzyme in a bioreactor would be obtained at a hydrat ion level below optimal for catalytic activty. The data also indicates that a significant destabilisation of the protein's unfolded state oc curs at low values of A(w).