Definition of pepsin in English:



mass nounBiochemistry
  • The chief digestive enzyme in the stomach, which breaks down proteins into polypeptides.

    • ‘Many people take extra doses of naturally produced enzymes, such as lactase, pepsin and trypsin, in supplement form.’
    • ‘Proteins in the stomach are broken down to polypeptides by the enzyme pepsin, which works best in acidic environments and is produced by ‘chief’, or ‘zymogen’, cells in the gastric mucosa.’
    • ‘The gastric enzyme, pepsin, along with hydrochloric acid, help break proteins into smaller units called peptones.’
    • ‘The essential oils in this herb ease muscle spasms in your gastrointestinal tract and may also decrease your body's production of pepsin, a digestive enzyme that exacerbates indigestion.’
    • ‘Such damage results from the low pH of stomach acids working in conjunction with the digestive enzyme pepsin.’


Mid 19th century: from Greek pepsis ‘digestion’ + -in.