Activation cascade, pancreatic proteases

Figure 26-2. The pancreatic enzyme cascade. Pancreatic proteases enter the intestinal lumen as inactive zymogens. Within the duodenum, a specific enzyme of the duodenal mucosa, enterokinase, activates trypsinogen by releasing the trypsinogen activation peptide (TAP). Subsequently, active trypsin activates the other zymogens and acts autocat-alytically.

Figure 12-8 Cascade of reactions that activate pancreatic proteases. Enteropeptidase, or trypsin, cleaves the proenzyme (zymogen) at specific sites.

The trypsin family of proteases plays a role in acute and chronic pancreatitis, as well as leads to its ultimate destruction [4, 105]. In pancreatitis, active exocrine enzymes are prematurely released inside the pancreatic duct. Various factors can contribute to the development of acute pancreatitis. Trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase are inactive proforms of proteolytic enzymes produced by the pancreatic acinar cells. Following secretion these enzymes are activated in a cascade that converts trypsinogen to trypsin in the duodenum and/or small intestine. 

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