pepsin
| Pepsin 3A | ||
|---|---|---|
|
||
| Pepsin inhibited by pepstatin | ||
| Properties of human protein | ||
| Mass / length primary structure | 326 and 332 amino acids, respectively | |
| Precursor | Pepsinogen, 373 aa | |
| Identifier | ||
| Gene name | PGA3 | |
| External IDs |
|
|
| Drug information | ||
| ATC code | A09 AA03 | |
| Enzyme classification | ||
| EC, category | 3.4.23.1 , endopeptidase | |
| MEROPS | A1 | |
| Response type | Hydrolysis ( proteolysis ) | |
| Substrate | Proteins | |
| Products | Peptides | |
| Occurrence | ||
| Homology family | Aspartine endopeptidase | |
| Parent taxon | Eukaryotes | |
Pepsin (from ancient Greek πέψις pepsis , "digestion") is a digestive enzyme , a so-called peptidase , which is formed in the main cells of the gastric fundus of vertebrates and thus also of humans. It is responsible for the breakdown of the food captured proteins ( proteins responsible). As an ingredient in food or in pepsin wine , it is said to aid digestion.
history
The basis for Johann Nepomuk Eberle's attempt in 1834 to enrich pepsin from cattle stomachs and thus to prove that protein digestion is a chemical process, were the records of Friedrich Tiedemann and Leopold Gmelin .
Johannes Müller suspected pepsin to be an enzyme that promotes meat digestion and adopted the term "contact ferment" introduced by Eilhard Mitscherlich . Pepsin was discovered as the first animal enzyme in 1836 by the German physiologist Theodor Schwann . In 1839, Adolph Wasmann (1807-1853) published instructions on how to obtain pepsin by precipitation. Friedrich Heinrich Bidder was finally able to prove that hydrochloric acid is necessary for the stomach , that it can digest and that the pepsin must be activated by the hydrochloric acid .
Boudault was not familiar with Bidder's experiments and must therefore also be regarded as the discoverer of pepsinogen , as he came to the same results.
In 1874, the pepsinogen was then detected in the gastric mucosa by Wilhelm Ebstein and Paul Grützner .
Napoleon III's personal physician , Lucien Corvisart (1824–1882), has been using gastric juice from animals since 1852 to treat patients with dyspepsia . He was advised to manufacture pepsin directly using Wasmann's method in order to increase acceptance. The works “Pharmacopoea germanica” (1872) also contain monographs on “Pepsinum” and “ Vinum Pepsini ” that document the treatment of gastric indigestion. In 1873 the first pepsin preparation by Friedrich Witte (Rostock) came onto the market.
In 1890 a process for obtaining pepsin on a larger scale, e.g. B. from 200 pig stomachs, patented. The pure crystalline pepsin was first described in 1929 by John Howard Northrop , an American chemist . In 1898, Caleb Bradham from New Bern ( North Carolina ) named the soft drink “ Pepsi Cola” after the most important ingredients pepsin and colanus extract .
properties
Pepsin is an acidic endopeptidase with a molecular mass of 36,000 Daltons . It is a phosphoprotein with a length of 327 amino acids . It is formed from an inactive precursor, pepsinogen, under the action of hydrochloric acid in the stomach . The cleavage takes place without the action of another enzyme (auto proteolysis ).
Two aspartates ( aspartic acid ) are found in the active center as functional amino acids. This catalyzes the breakdown of proteins into high molecular weight, water-soluble peptones . Pepsin cleaves preferentially at the N-terminus of phenylalanine, the most common pattern is P / - / - / FL + - / R / L / -, so the catalysis behavior is sequence-specific .
Pepsin has the highest activity at a pH value between 1.5 and 3.
The function of the enzyme decreases significantly above pH 4. From a pH of 7 the enzyme is irreversibly denatured.
Temperatures of up to 60 ° C cannot impair its function, nor can higher concentrations of urea and guanidine . In the freeze-dried state, pepsin can be stored for a few months at 4 ° C.
use
Pepsin works well for studying disulfide bridging in other proteins. Since the cleavage is carried out at low pH values, the risk of disulfide exchange reactions is low. The commercially available form of pepsin is mostly pepsin from the pig's stomach .
See also
Individual evidence
- ↑ a b c d e f Wolf-Dieter Müller-Jahncke , Christoph Friedrich , Ulrich Meyer: Medicinal history . 2nd, revised and expanded edition. Wissenschaftliche Verlagsgesellschaft, Stuttgart 2005, ISBN 978-3-8047-2113-5 , p. 112 f .
- ↑ Marcel Florkin: La découverte de la pepsine by Théodore Schwann [Discovery of pepsin by Theodor Schwann] . In: Revue Médicale De Liège . tape 12 , no. 5 , March 1, 1957, p. 139-144 , PMID 13432398 (French).
- ↑ Patent US433395 : Obtaining Pepsin. Registered April 3, 1889 , published July 29, 1890 , inventor: John Brill.
- ^ John H. Northrop: Crystalline Pepsin . In: Science . tape 69 , no. 1796 , May 31, 1929, pp. 580-580 , doi : 10.1126 / science.69.1796.580 , PMID 17758437 ( sciencemag.org [accessed January 7, 2017]).
- ^ Soda Museum - The History of Pepsi-Cola ( Memento of February 12, 2008 in the Internet Archive )
- ↑ MEROPS entry
- ↑ John Del Valle: Peptic Ulcer and Related Disorders in Dan L. Longo, Anthony S. Fauci, Dennis L. Kasper, Stephen L. Hauser, J. Larry Jameson, Joseph Localzo (Eds.): Harrison's Principles of Internal Medicine. 18th edition, Volume 2, New York, 2012, p. 2441
