It is a serine protease enzyme that is produced in the pancreas as the proenzyme trypsinogen. Trypsinogen is activated into the active form it through the catalytic action of another pancreatic enzyme called enteropeptidase.

Role in Digestion

It plays a crucial role in digestion by initiating the breaking down of proteins consumed in food into smaller peptides and amino acids. In the small intestine, it cleaves peptide linkages on the carboxyl side of lysine and arginine residues of proteins and peptides from partially digested food. This action activates other pancreatic proenzymes like chymotrypsin and procarboxypeptidases which then help further break down proteins into absorbable forms.

A Trypsin is a single-chain polypeptide containing 223 amino acids that folds into two domains linked by a short peptide. It contains a catalytic triad made up of histidine, aspartate, and serine amino acids at its active site. It catalyzes the hydrolysis of peptide bonds where the carboxyl side of the bonds contains arginine or lysine amino acid residues. The preferred cleavage site of it is the carboxyl end of arginine or lysine residues.

Production and Activation

The production of trypsinogen occurs in the acinar cells of the pancreas through a series of steps. The gene sequences for trypsinogen are translated on ribosomes into trypsinogen precursor proteins within the rough endoplasmic reticulum of pancreatic cells. These precursors then undergo post-translational modifications while traversing the Golgi apparatus. Mature trypsinogen granules are packaged into secretory vesicles and released into the small intestine through exocytosis upon stimulation by food proteins in the intestine. Enteropeptidase, a protease secreted by the small intestine, then cleaves trypsinogen to remove an N-terminal peptide segment, converting it into the active trypsin enzyme.

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