Pepsin

WikiDoc Resources for Pepsin
Articles
Most recent articles on Pepsin Most cited articles on Pepsin Review articles on Pepsin Articles on Pepsin in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Pepsin Images of Pepsin Photos of Pepsin Podcasts & MP3s on Pepsin Videos on Pepsin
Evidence Based Medicine
Cochrane Collaboration on Pepsin Bandolier on Pepsin TRIP on Pepsin
Clinical Trials
Ongoing Trials on Pepsin at Clinical Trials.gov Trial results on Pepsin Clinical Trials on Pepsin at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Pepsin NICE Guidance on Pepsin NHS PRODIGY Guidance FDA on Pepsin CDC on Pepsin
Books
Books on Pepsin
News
Pepsin in the news Be alerted to news on Pepsin News trends on Pepsin
Commentary
Blogs on Pepsin
Definitions
Definitions of Pepsin
Patient Resources / Community
Patient resources on Pepsin Discussion groups on Pepsin Patient Handouts on Pepsin Directions to Hospitals Treating Pepsin Risk calculators and risk factors for Pepsin
Healthcare Provider Resources
Symptoms of Pepsin Causes & Risk Factors for Pepsin Diagnostic studies for Pepsin Treatment of Pepsin
Continuing Medical Education (CME)
CME Programs on Pepsin
International
Pepsin en Espanol Pepsin en Francais
Business
Pepsin in the Marketplace Patents on Pepsin
Experimental / Informatics
List of terms related to Pepsin

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 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
• Pepsin+A at the US National Library of Medicine Medical Subject Headings (MeSH)
• Pepsinogens at the US National Library of Medicine Medical Subject Headings (MeSH)
• Pepsinogen+A at the US National Library of Medicine Medical Subject Headings (MeSH)
• Pepsinogen+C at the US National Library of Medicine Medical Subject Headings (MeSH)