Pepsin
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| Pepsin | |
|---|---|
 Pepsin in complex with pepstatin | |
| Other names: | Pepsinogen |
| Genetic data | |
| Gene code: | 8885 (HGNCid) |
| Protein Structure/Function | |
| Protein type: | protease |
| Functions: | digestion |
| Other | |
| Molecular interactions: | pepstatin |
| Database Links | |
| EC number: | 3.4.23.1 |
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Ongoing Trials on Pepsin at Clinical Trials.gov Clinical Trials on Pepsin at Google
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US National Guidelines Clearinghouse on Pepsin
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Directions to Hospitals Treating Pepsin Risk calculators and risk factors for Pepsin
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Overview
Pepsin is a digestive protease (EC 3.4.23.1) released by the chief cells in the stomach that functions to degrade food proteins into peptides.
According to American Heritage Dictionary, pepsin derives from the Greek word pepsis, meaning digestion (peptein: to digest).
Pepsin was discovered by Theodor Schwann[1] in 1836. It was the first animal enzyme to be discovered.
Precursor
Pepsin is expressed as a pro-form zymogen, pepsinogen, whose primary structure has an additional 44 amino acids.
In the stomach, chief cells release pepsinogen. This zymogen is activated by hydrochloric acid (HCl), which is released from parietal cells in the stomach lining. The hormone gastrin and the vagus nerve trigger the release of both pepsinogen and HCl from the stomach lining when food is ingested. HCl creates an acidic environment which allows pepsinogen to unfold and cleave itself in an autocatalytic fashion, thereby generating pepsin (the active form). Pepsin cleaves the 44 amino acids from pepsinogen to create more pepsin. Pepsin will digest up to 20% of ingested carbon bonds by cleaving preferentially after the N-terminal of aromatic amino acids such as phenylalanine and tyrosine. It will not cleave at bonds containing valine, alanine or glycine. Peptides may be further digested by other proteases (in the duodenum) and eventually absorbed by the body.
Pepsin is stored as pepsinogen so it will only be released when needed, and does not digest the body's own proteins in the stomach's lining.
Pepsin functions best in acidic environments, particularly those in a pH of 3.
See also
Other important digestive proteases are the pancreatic enzymes trypsin and chymotrypsin. Pepsin denatures if the pH is more than 5.0. Pepsin is potently inhibited by the peptide inhibitor pepstatin.
Storage
Pepsins should be stored at very cold temperatures (between −20°C and −80°C) to prevent autolysis (self-cleavage). Autolysis may also be prevented by storage of pepsins at pH 11 or by using pepsins modified by e.g. reductive methylation. When the pH is adjusted back to pH 6 activity returns.
External links
- Pepsin A description from BRENDA database
- MeSH Pepsin+A
- MeSH Pepsinogens
- MeSH Pepsinogen+A
- MeSH Pepsinogen+C
References
Digestive system, physiology: gastrointestinal physiology | |
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| Enteric nervous system | Meissner's plexus - Auerbach's plexus |
| Exocrine | Chief cells (Pepsinogen) - Parietal cells (Gastric acid, Intrinsic factor) - Goblet cells (Mucus) |
| Endocrine/paracrine | G cells (gastrin), D cells (somatostatin) - ECL cells (Histamine) - enterogastrone: I cells (CCK), K cells (GIP), S cells (secretin) |
| Border | Brunner's glands - Paneth cells - Enterocytes |
| Fluids | Saliva - Bile - Intestinal juice - Gastric juice - Pancreatic juice |
| Processes | Swallowing - Vomiting - Peristalsis (Interstitial cell of Cajal) - Migrating motor complex - Borborygmus - Gastrocolic reflex - Segmentation contractions - Defecation |
Proteases: aspartic acid proteases (EC 3.4.23) | |
|---|---|
| Vertebrate | Pepsin · Chymosin · Renin · Signal peptide peptidase · Beta secretase |
| Pathogenic | Plasmepsin · HIV-1 protease |
cy:Pepsin da:Pepsin de:Pepsineo:Pepsino fr:Pepsine ko:펩신 it:Pepsina he:פפסין nl:Pepsine ja:ペプシン no:Pepsinsimple:Pepsin th:เพพซิน fi:Pepsiini sv:Pepsin ur:پیپسن
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
