/pep"sin/, n. Biochem.
1. an enzyme, produced in the stomach, that in the presence of hydrochloric acid splits proteins into proteoses and peptones.
2. a commercial form of this substance, obtained from the stomachs of hogs, used as a digestive, as a ferment in the manufacture of cheese, etc.
Also, pepsine.
[1835-45; < Gk péps(is) digestion (pep-, base of péptein to digest + -sis -SIS) + -IN2]

* * *

Powerful enzyme in gastric juice (see stomach) that partially digests proteins in food.

Glands in the stomach lining make pepsinogen, a zymogen (enzyme precursor) converted to pepsin by the hydrochloric acid in gastric juice. Pepsin is active only in the acid environment of the stomach (pH 1.5–2.5 or less); it is ineffective in the intestine (pH 7, neutral). It is used commercially in some cheese making, in the leather industry to remove hair and residual tissue from hides, and in the recovery of silver from discarded photographic films by digesting the gelatin layer that holds the silver.

* * *

 the powerful enzyme in gastric juice that digests proteins such as those in meat, eggs, seeds, or dairy products.

      Pepsin was first recognized in 1836 by the German physiologist Theodor Schwann. In 1930 it was crystallized and its protein nature established by John H. Northrop of the Rockefeller Institute for Medical Research.

      Glands in the mucous-membrane lining of the stomach make and store an inactive protein called pepsinogen. Impulses from the vagus nerve and the hormonal secretions of gastrin and secretin stimulate the release of pepsinogen into the stomach, where it is mixed with hydrochloric acid and rapidly converted to the active enzyme pepsin. The digestive power of pepsin is greatest at the acidity of normal gastric juice (pH 1.5–2.5). In the intestine the gastric acids are neutralized (pH 7), and pepsin is no longer effective.

      In the digestive tract pepsin effects only partial degradation of proteins into smaller units called peptides, which then either are absorbed from the intestine into the bloodstream or are broken down further by pancreatic enzymes.

      Small amounts of pepsin pass from the stomach into the bloodstream, where it breaks down some of the larger, or still partially undigested, fragments of protein that may have been absorbed by the small intestine.

      Pepsin is prepared commercially from swine stomachs. Crude pepsin is used in the leather industry to remove hair and residual tissue from animal hides prior to their being tanned. It is also used in the recovery of silver from discarded photographic films by digesting the gelatin layer that holds the silver compound.

* * *

Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Pepsin — 3A Pepsin gehemmt durch Pepstatin nach PDB  …   Deutsch Wikipedia

  • pepsin C — pepsin similar to pepsin A but highly active with hemoglobin as substrate. In EC nomenclature called gastricsin …   Medical dictionary

  • Pepsin — Pepsin, den Endopeptidasen (⇒ Proteinasen) zugehörendes, eiweißspaltendes Verdauungsenzym des Wirbeltiermagens, dessen Optimum im pH Bereich zwischen 1,5 und 2,5 liegt. P. wird von den Magenzellen in Form einer inaktiven Vorstufe, dem Pepsinogen …   Deutsch wörterbuch der biologie

  • pepsin — [pep′sin] n. [Ger: coined (1836) by T. Schwann (1810 82), Ger physiologist < Gr pepsis, digestion < peptein, earlier pessein, to cook, digest < IE base * pekw > L coquere,COOK] 1. a digestive enzyme in the gastric juice of stomach… …   English World dictionary

  • Pepsin — Pep sin, n. [Gr. ? a cooking, digesting, digestion, fr. ?, ?, to cook, digest: cf. F. pepsine. Cf. {Dyspepsia}.] (Physiol. Chem.) An unorganized proteolytic ferment or enzyme contained in the secretory glands of the stomach. In the gastric juice… …   The Collaborative International Dictionary of English

  • pepsin — pepsin. См. пепсин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Pepsin — Pepsin, ein eigenthümliches Ferment im Magensaft, welchem dieser seine verdauende Kraft verdankt; es wirkt in Verbindung mit etwas Säure verdauend auf die Proteïnverbindungen, indem dieselben in die sogenannten Peptone umgewandelt werden. Es ist… …   Pierer's Universal-Lexikon

  • Pepsīn — Pepsīn, fermentartig wirkende Substanz, die von den Labdrüsen der Magenschleimhaut abgesondert wird und bei Anwesenheit von etwas Salzsäure eiweißartige Körper und leimgebende Gewebe nicht nur auflöst, sondern auch in Albumosen und Peptone… …   Meyers Großes Konversations-Lexikon

  • Pepsin — Pepsīn (vom griech. pépsis, Verdauung), das Ferment, das von der Magenschleimhaut ausgesondert wird und bei Anwesenheit von etwas Salzsäure die eiweißartigen Körper auflöst und in Peptone (s.d.) verwandelt; wird künstlich hergestellt durch… …   Kleines Konversations-Lexikon

  • pepsin — also pepsine, fermin in gastric juice, used medicinally for cases of indigestion, 1844, coined in German (1836) from Gk. pepsis “digestion,” from stem pep (see PEPTIC (Cf. peptic)) + IN (Cf. in) (2) …   Etymology dictionary

  • pepsin — pèpsīn m <N mn pepsíni> DEFINICIJA fiziol. ferment želučanog soka, razgrađuje bjelančevine na peptone i time pomaže probavu ETIMOLOGIJA grč. pépsis: kuhanje, vrenje + in …   Hrvatski jezični portal

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”