Pancreas tyrosine-activating enzyme

Bovine carboxypeptidase A is produced in the pancreas as a zymogen, procarboxypeptidase A, MW = 87,000. The proenzyme is composed of three polypeptide chains (151, schematically shown in Figure 15). On limited digestion with trypsin one or more peptide bonds in subunit II is split resulting in its conversion to an enzyme (ATEEase) having activity on acetyl-L-tyrosine ethyl ester similar to that of chymotrypsin. Continued... 

The first data on the enzymes of the pancreatic juice were furnished by Cl. Bernard in 1855 and Corvisart in 1858. It is to the latter that we owe the name of pancreatin, given to the active constituents of the pancreatic juice. Danilewsky, in 1862, isolated from a maceration of pancreas three enzymes, one amylolytic, a second proteolytic, and finally a third, capable of emulsifying and of saponifying fatty substances. Kiihnc, in 1867, first drew attention to the difference which exists between the chemical action of pepsin and that of the pancreatic enzyme. He showed the production, in this second action, of tyrosin and leucin, and also of those ill-defined residues from the hydrolysis of albuminoids which he called anti-peptones. He then characterized this proteolytic enzyme as a new enzyme, distinct from pepsin, and gave to it the name of trypsin. 

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