Papain (Protease from Papaya)
Probiotics & Enzymes
Overview
- Papain is a cysteine-type proteolytic enzyme extracted from the latex of ripe Carica papaya fruit.
- It hydrolyzes peptide bonds in proteins.
- This makes it a natural digestive aid and versatile tool in food processing, cosmetics, and medical applications.
- As a supplement, papain primarily supports protein digestion and promotes the breakdown of proteinaceous waste in the gastrointestinal tract.
Chemistry
- Papain (EC 3.4.22.2) is a single-chain polypeptide of 212 amino acids with a molecular weight of 23 kDa (C₁₁₆₉H₁₈₁₇N₃₁₅O₃₅₈S₁₁).
- Its three-dimensional structure is a typical papain-like cysteine protease fold: an α-helical domain, a β-sheet domain, and a flexible “hinge” region.
- The catalytic cysteine (Cys-25) forms a thiol-imidate intermediate during peptide bond cleavage.
- Papain is stable at pH 4–7, with optimal activity at pH 5–6, and retains activity up to 70 °C for short periods.
- The enzyme is glycosylated (≈10 % carbohydrate) and contains a disulfide-rich core that confers resistance to proteolysis.
- The IUPAC name is not routinely assigned because it is a protein, not a small molecule; it is described by its UniProt entry P00784.
Sources & Quality
- Commercial papain is primarily extracted from the latex of ripe Carica papaya fruits grown in tropical regions (India, Brazil, Costa Rica).
- Latex is collected by incising the fruit, allowing the milky sap to flow, then the sap is centrifuged, filtered, and precipitated (often with ethanol or acetone) to obtain the crude enzyme.
- The crude extract is then purified by ion-exchange chromatography, ultrafiltration, and spray-drying to produce a stable powder.
- Some manufacturers use recombinant expression in Pichia pastoris or Escherichia coli for higher purity and reduced allergenicity.
- Quality-focused supplements provide a “papain activity” label (e.g., 30 U/mg) and conduct testing for microbial contamination, heavy metals, and residual latex proteins to ensure safety for consumers.
Where to Buy Papain (Protease from Papaya)
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