Function
Trypsin in the duodenum catalyses the hydrolysis of peptide bonds so that proteins can be broken down into smaller peptides. These peptides may then be further hydrolysed into amino acids by other proteases before they enter the blood stream. Tryptic digest is a necessary step in protein absorption because proteins are generally too big to be absorbed through the lining of the small intestine.
Trypsin is produced in the pancreas in the form of the inactive zymogen trypsinogen. When the pancreas is stimulated by cholecystokinin, it is then secreted into the first part of the small intestine (the duodenum) via the pancreatic duct. Once in the small intestine, the enzyme enteropeptidase activates it into trypsin by proteolytic cleavage. Trypsin can then function to activate additional trypsinogen (autocatalysis), so only a small amount of enteropeptidase is necessary to start the reaction. This activation mechanism is common for most serine proteases, and serves to prevent autodegradation of the pancreas.
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