Papain

It is a cysteine hydrolase hydrolase that is stable and active under a awide range of conditions. It is very stable even at elevated temperatures(cohen et al. 1986). The latex of Carica papaya is a rich source of four cysteine endopeptidases including papain, chymopapain, glycyl endopeptidase, and caricain. The proteins are synthesized as inactive precursors that become acctive with two minutes of the plant being wounded and the latex expelled. Papain is a minor constituent, but has been more widely studied because it is more easily purified (Azarkan 2003).

Molecular Weight:

• 23.4 kDa (theoretical)
• 23.0 kDa (Dreuth et al. 1968)

Active site residies:

• cysteine (c158)
• histidine (h292)
• asparagine (n308)
  

Applications:

• cell isolation where it is more gentle than other proteases (i.e.: cortical neurons, retina, and smooth muscle)
• protein structural studies, peptide mapping
• Red cell surface modification for antibody screening or identification
• Fab preparation from IgG and IgM antibodies
• Solubilization of integral membrane proteins
• production og glycopeptides from purified proteoglycans
• Enzymatic wound debridement

Akahane, K. and Umeyama,H. (1986) Binding Specificity of Papain and Cathepepsin B, Emzyme 36, 141

Cohen, L., Coghlan, V and Dihel, L. (1986) Cloning and Sequencing of papain-encoding cDna, Gene 48, 219, 1986

Drenth, J., Jansonius, J. Koekoek,R., Swen, H., and Wolters, B.(1968) Structure of Papain, Nature 218, 929