Papain is a sulfhydryl protease from Carica papaya latex. (A second protease, chymopapain, and a lysozyme have also been isolated from this same source.) Since native crystalline papain is quite unreactive until acted upon by mild reducing agents such as cysteine or cyanide, it may exist as a zymogen.
Papain is widely used in cell isolation. With some tissues papain has proved less damaging and more effective than other proteases. Of the enzymes used for dissociating turtle retina, papain produced the least trauma. Intact single photoreceptor cells have also been isolated from adult salamander retina with papain. Papain used to obtain high yields of viable, morphologically intact cortical neurons from postnatal rats. Used for dissociation of postnatal rat hippocampus. Papain is used with fetal as well as postnatal brain regions to provide maximal dissociation and viability of neurons. It is also used to produce Fab fragments of antibodies. In addition, papain is used in red cell serology to modify the red cell surface to enhance or destroy the reactivity of many red cell antigens. Papain is useful for platelet serology studies. Papain has also been used in the enzymatic synthesis of amino acids, peptides, and other molecules.
Papain is a cysteine protease that cleaves peptide bonds of basic amino acids, leucine, or glycine. It is also hydrolyzes esters and amides. Papain consists of a single polypeptide chain with three disulfide bridges and a sulfhydryl group necessary for activity of the enzyme.
Grade: Technical
Specific Activity: >1750 USP u/mg
Key Applications: For production of Fab fragments of antibodies, Used for cell dissociation
Product Type: Proteins, Enzymes & Peptides
Extinction Coefficient (E1%): 25.0 (Lit.)
Presentation: Powder
Format: Powder
Isoelectric point (pI): pH 9.6 (Lit.)
pH: Optimum pH: 6.0 - 7.0(Lit.)
Loss on Drying: ≤8%
NOTES: Activators: Papain is activated by cysteine, sulfide, sulfite, etc. It is enhanced when heavy metal binding agents such as EDTA are also present. N-bromosuccinimide enhances the activity. Inhibitors: Substances which react with sulfhydryl groups including heavy metals, carbonyl reagents. Aldehydes are papain inhibitors. Benzoylamidoacetonitrile is an inhibitor. See Shapira and Arnon (1967a and b) on antibody inhibitors. Papain may be inactivated by H2O2 generated by γ-irradiation of H2O- the active SH group being oxidized to sulfenic acid. Specific inhibitors are AEBSF, antipain, cystatin, E-64, leupeptin, PMSF, TLCK and TPCK.
Storage & Handling: Store at +4°C, desiccate.