THE ACTIVATION OF CHYMOTRYPSINOGEN B: I. FACTORS AFFECTING THE GENERATION OF CHYMOTRYPTIC ACTIVITY

The bovine pancreatic zymogen, chymotrypsinogen B, can be activated by trypsin to form chymotrypsin B. The rate of activation, maximum enzymic activity, and the stability of this activity were found to be influenced by such factors as pH, temperature, trypsin concentration, Ca++ ions, and inhibitors. The results are discussed and compared with the events known to occur during chymotrypsinogen A activation. Although chymotrypsinogen B is activated more rapidly than chymotrypsinogen A, the resulting esterase activity is lower. There is evidence to suggest that, besides the initial break in the polypeptide chain catalyzed by trypsin, further autolytic cleavages take place which result in forms of chymotrypsin B with reduced esterase activity.