DENATURATION AND INACTIVATION OF ENZYME PROTEINS

III. DENATURATION AND INACTIVATION OF TAKA-α-AMYLASE

抄録

Inactivation and denaturation of crystalline Taka-α-amylase were investigated in the case of heat, urea and acid treatment. The “ratio of inactivation” (RI) and the “ratio of denaturation” (RD) of the amylase well coincided with one another at every stage in the duration of heat and urea treatment, and the time course of denaturation (in-activation) of the amylase in the above treatment proceeded almost in accordance with the unimolecular reaction. Protective effect of calcium ion on the inactivation and denaturation of the amylase was the same as in the case of bacterial amylase (4). When the amylase was treated in an acidic solution, the amylase was reversibly denatured and, therefore, the “RD” did not coincided with the “RI” measured by the ordinary procedure, on account of the reactivation in the assaying procedure. But, when the activity was measured after the proteolysis, by which the reactivatable molecules were removed, the “RD” and the “RI” well coincided with one another at every stage in the course of acid denaturation. The same result as above was obtained in the process of reactivation of acid denatured Taka-α-amylase. Therefore, the proteolytic method for determining the “RD” of the partially denatured protein is confirmed to be useful even in the reversible denaturation and renaturation process.