Pepsin
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Pepsin is a protease, a digestive enzyme that degrades food proteins in the stomach. According to American Heritage Dictionary, its name derives from the Greek pepsis that means digestion (peptein, to digest). The other important digestive enzymes are the pancreatic enzymes trypsin and chymotrypsin. It was the first animal enzyme to be discovered, by Theodor Schwann in 1836.
Pepsin is expressed as a pro-form, pepsinogen with an additional 44 amino acids, which are cleaved off outside the secreting cell, to avoid digestion of the cells of the stomach and pancreas (like all cells, their membranes contain protein).
Pepsin is most active at pH 2-4 (acidic), pepsin is activated from pepsinogen by hydrochloric acid from the stomach wall. It is permanently inactivated above pH 6 (weak acid).
The name Pepsi is derived from pepsin. Pepsin is also used in the preparation of cheese.
External links
- Pepsin product information from China GreatVista Chemicals (http://www.greatvistachemicals.com/biochemicals/pepsin.html)