Activation of chymotrypsinogen B

Abstract

During the process of activation of chymotrypsinogen B at least 3 stages of activity levels can be distinguished. The first is the least stable, the third the most stable. With the same concentration of enzyme precursors and activating trypsin (EC 3.4.4.4) the initial rate of formation of chymotrypsin B (EC 3.4.4.6) is about 25 times higher than that of α-chymotrypsin (EC 3.4.4.5). With a constant time and varied concentration of trypsin, chymotrypsinogen B reaches a maximum activity level with one-tenth the amount of trypsin required to reach a maximum activity for α-chymotrypsinogen. The first activating cleavage is the same in both enzyme precursors and involves the bond arginine-isoleucine.