THERMAL-STABILITY OF A NEUTRAL PROTEASE OF ASPERGILLUS-ORYZAE

The thermal stability of the neutral protease of Aspergillus oryzae wa s measured by differential scanning calorimetry. The activation energy , preexponential factor and the reaction rate constant calculated by m eans of the dynamic method are similar to those obtained for denaturat ion of other proteins. Half life (t1/2) calculated by using the above- mentioned parameters permitted estimation of the amount of native enzy me remaining after different thermal treatments. Complete denaturation occurred above 60C. The presence of substrate stabilizes the enzyme. The behavior of flour samples treated with the neutral protease was st udied as well. A tendency to shift towards higher temperatures when fl our was treated with the enzyme was observed for both the T(p) (DSC pe ak maximum temperature) corresponding to gelatinization of starch and the dissociation of the amylose-lipid complex.