Pepsin

Pepsin is an enzyme that plays a crucial role in the digestive system. It is produced in the stomach and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pepsin has a three dimensional structure, of which one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, or the location on the enzyme where the substrate binds and the reaction takes place.

Structure

Pepsin is an aspartic protease, using a catalytic aspartate in its active site. It is part of a family of enzymes that use a catalytic aspartate in their active site. Pepsin's aspartic acid residues are located in the N-terminal domain.

Function

Pepsin is expressed as a zymogen called pepsinogen, whose primary structure has an additional 44 amino acids compared to the active enzyme. In the stomach, gastric chief cells release pepsinogen. This zymogen is activated by the stomach acid into the active protease pepsin, which is largely responsible for the stomach's ability to initiate digestion of proteins.

Clinical significance

Pepsin remains in the larynx (pH 6.8) following a gastric reflux event. Pepsin may also cause mucosal damage during weakly acidic or non-acid gastric reflux. Such damage to the laryngeal tissues may result in various symptoms, such as hoarseness, voice changes, or a sensation of a lump in the throat.

See also

• Digestive enzyme
• Stomach
• Protein

Pepsin Resources
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