Pepsinogen

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The peptide pepsinogen is the inactive precursor of the digestive enzyme pepsin . The latter is created under the action of hydrochloric acid by splitting off 44 amino acids . Pepsinogen is produced in the fundic glands in the stomach.

Pepsinogen ( molecular mass : 42,500) is produced and released as a so-called zymogen - an inactive enzyme precursor - by the main cells of the stomach . The cleavage takes place at the N-terminal end autocatalytically in an acidic medium. This mechanism ensures that the pepsin does not already digest the cell's own components in the cells themselves.

The formation of pepsinogen is stimulated by gastrin and probably also by the gastrin releasing peptide (GRP).

history

At the end of the 19th century, the role of pepsin as a digestive agent in the stomach was established, but for decades the idea that enzymes were small molecules bound to protein as a carrier substance was stuck to. Langley observed as early as 1882 that a slightly alkaline extract of the gastric mucosa contained an inactive precursor of pepsin, which could be converted to pepsin by acidification. The isolation and crystallization of pepsinogen occurred in 1936 by Herriott and Northrop after Northrop did the same with pepsin in 1930. The work of these two researchers not only clarified the existence and properties of these substances, but also generally confirmed the fact that proteins can have catalytic activity, for which Northrop and Sumner received the 1946 Nobel Prize in Chemistry .

Individual evidence

  1. ^ Emil Fischer: Significance of stereochemistry for physiology . In: Z. physiol. Chemistry . 26, 1898, pp. 60-87.
  2. ^ John Newport Langley: J. Physiol. (London) 3, 246 (1882); John Newport Langley, B. Edkins: ibid. 7, 371 (1888)
  3. ^ John Howard Northrop: Crystalline Pepsin I. Isolation and Tests of Purity . In: J. Gen. Physiol. . 13, 1930, p. 739. PMC 2141071 (free full text).
  4. ↑ Roger M. Herriott, John Howard Northrop: Isolation of crystalline pepsinogen from swine gastric mucosae and its autocatalytic conversion into pepsin . In: Science (journal) . 83, No. 2159, May 1936, pp. 469-470. doi : 10.1126 / science.83.2159.469 . PMID 17796849 .
  5. ↑ John Howard Northrop, Moses Kunitz, Roger M. Herriott: Crystalline Enzymes. (= Columbia biological series. 12.) 2nd ed., Columbia Univ. Press, New York 1948, OCLC 2387458 .