Where is enterokinase released from

The pancreas secretes a magnificent battery of enzymes that collectively have the capacity to reduce virtually all digestible macromolecules into forms that are capable of, or nearly capable of being absorbed.

Three major groups of enzymes are critical to efficient digestion:. Digestion of proteins is initiated by pepsin in the stomach , but the bulk of protein digestion is due to the pancreatic proteases.

Several proteases are synthesized in the pancreas and secreted into the lumen of the small intestine. The two major pancreatic proteases are trypsin and chymotrypsin , which are synthesized and packaged into secretory vesicles as the inactive proenzymes trypsinogen and chymotrypsinogen. As you might anticipate, proteases are rather dangerous enzymes to have in cells, and packaging of an inactive precursor is a way for the cells to safely handle these enzymes.

The secretory vesicles also contain a trypsin inhibitor which serves as an additional safeguard should some of the trypsinogen be activated to trypsin; following exocytosis this inhibitor is diluted out and becomes ineffective - the pin is out of the grenade.

Once trypsinogen and chymotrypsinogen are released into the lumen of the small intestine, they must be converted into their active forms in order to digest proteins. Trypsinogen is activated by the enzyme enterokinase , which is embedded in the intestinal mucosa. Once trypsin is formed it activates chymotrypsinogen, as well as additional molecules of trypsinogen.

The net result is a rather explosive appearance of active protease once the pancreatic secretions reach the small intestine. Trypsin and chymotrypsin digest proteins into peptides and peptides into smaller peptides, but they cannot digest proteins and peptides to single amino acids.

Bile salts may also play a role through a nonselective detergent effect. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve. Kunitz M: Formation of trypsin from crystalline trypsinogen by means of enterokinase. J Gen Physiol —, Google Scholar. Biochim Biophys Acta —, Lancet —, Res Exp Med —25, Acta Gastroenterol Belg —, Lebenthal E, Antonowitz I, Schwachman H: The interrelationship of enterokinase and trypsin activity in intractable diarrhea of infancy, celiac disease, and intravenous alimentation.

Pediatrics —, Lebenthal E, Lee PC: Effect of pancreozymin and secretin on intraluminal enterokinase, trypsin, and chymotrypsin activities of cystic fibrosis and control children.

Digestion —47, Biochim Biophys Acta —40, Am J Dig Dis —, Proc Soc Exp Biol Med —, Gut —, Res Exp Med —, Scand J Gastroenterol —, S Meitex ed. New York, Academic Press, , pp — Methods Enzymol —52, In Comprehensive Endocrinology: Gastrointestinal Hormones. New York, Raven Press, , pp — Mutt V: Cholecystokinin: Isolation, structure, and functions.

Other Products. Enteropeptidase also called enterokinase is an enzyme produced by cells of the duodenum and involved in human and animal digestion. Enteropeptidase converts trypsinogen a zymogen into its active form trypsin, resulting in the subsequent activation of pancreatic digestive enzymes.

Absence of enteropeptidase results in intestinal digestion impairment. Enterokinase is used for the cleavage of fusion proteins at definite cleavage sites. For the processing of recombinant proteins, the desired protein is fused with Enterokinase recognition sequence. After purification of the entire fusion protein, the protein or peptide is released by incubation with enterokinase. Serine protease acting as a restriction protease that recognizes the amino acid sequence - Asp 4-Lys-X. The aspartic acid residues can be partially substituted by glutamic acid.