Pepsin

• OMIM: 169710
• UniProt: P00790

• CAS Number: 9001-75-6

Pepsin (from Greek πέψις pepsis, " digestion" ) is a digestive enzyme known as a peptidase, which is formed in the main cells of the gastric fundus of vertebrates and thus also the people. She is responsible for the degradation of the ingested proteins. As an ingredient in food products, it is designed to promote digestion.

History

Pepsin was discovered as the first animal enzyme in 1836 by the German physiologist Theodor Schwann. For the first time in pure crystalline form, it was in 1930, presented by John Howard Northrop, an American chemist. 1898 named Caleb Bradham of New Bern (North Carolina) the soft drink "Pepsi Cola" after the main ingredients pepsin and Kolanussextrakt.

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. Made it under the action of hydrochloric acid of the stomach from an inactive precursor, pepsinogen. The cleavage takes place without the action of another enzyme ( autoproteolysis ).

Two Aspartate ( aspartic acid) are as functional amino acids in the active site. Through this, the cleavage of proteins into high molecular weight, water-soluble peptones is catalyzed. Pepsin cleaves preferentially at the N-terminus of phenylalanine, the most common pattern is P / / / FL -/R/L/-, the catalytic behavior is therefore a sequence-specific.

The highest activity has pepsin at a pH between 1.5 and 3 Above pH 6, the enzyme is irreversibly inactivated. Temperatures to 60 ° C may not interfere with its function, nor high concentrations of urea and guanidine. In a freeze-dried, pepsin may be stored at 4 ° C for several months.

Use

Pepsin is well suited to study the disulfide bridges in other proteins. Since the cleavage is carried out at low pH, the risk of disulfide is low. The commercially available pepsin form is mostly pepsin from the stomach of the pig.