抄録
The thermal inactivationoof the semi-alkaline proteinase from Aspergillus melleus, proceeded following the first order kinetics. The activation energy for the thermal inactivation was calculated to be 53 kcal per mol. Autolysis takes place directly proportional with the inactivation and the enzyme was degraded into oligopeptide and or amino acid. It was found that calcium ion, ammonium sulfate, glycerol and saccharose have a stabilizing effect on the semi-alkaline proteinase against the thermal inactivation. In the enzyme, 4-6 mol of calcium ion per mol of protein were found to bound, and by the loss of calcium ion, the enzyme became extremely unstable. In the presence of denaturing agents such as urea, guanidine-HCl and alcohols, the inactivation of the enzyme was accelerated and proceeded with first order kinetics. Activation energy for thermal inactivation decreased in the presence of urea and guanidine-HCl, but unchanged in the presence of alcohols. From these results, it was concluded that thermal inactivation of the semi-alkaline proteinase proceeded in two steps, that is, denaturation with conformational change and followed degradation with the residual proteinase. The rate limiting step was the denaturation.
