Trypsin is an enzyme that digests proteins (i.e. a protease). It is secreted in an inactive form (trypsinogen) by the pancreas into the duodenum. There, trypsinogen is acted on by an enzyme (enterokinase) produced in the duodenum to yield trypsin. The active enzyme plays an important role in the digestion of proteins, breaking down peptide bondsa> in the amino acids lysine and arginine, in the anterior portion of the small intestine. It also activates other proteases in the pancreatic juice.