Sandbox 32

Papain is a sulfhydrl protease from papaya latex (Carica papaya) and is used in food and pharmaceutical industries (6). It's PDB ID is 9PAP and it has an E.C. # of 3.4.22.2. It is a simple protease containing a single chain of amino acids.

Structure

Papain contains 212 amino acid resiudes and a molecular weight of 23.4 kDa. It's secondary structure contains 7 that make up 25% of the protein, and 17 making up about 17% (4). The remaining % of the structure is made up of....

In its 3D structure, Papain is stabilized by many hydrophobic interactions. These interactions have been shown to be very important in the overall structure and folding of the protein (6). In fact, papain is made up of , L and R (L=green and R=blue). The L domain contains alpha-helical structural components (residues 10-111, 208-212) while the R domain (residues 1-9, 112-207) is characterized by anti-parallel beta sheet structure (6). In addition to these interactions, the overall structure of papain is stabilized by three disulfide bonds.

The sulfhydryl protease contains many . There are also a few residues and no positively charged residues except for histidine. Along with these hydrophobic/hydrophillic interactions, also are important structural components. There are 6 cysteine residues that form disulfide bonds at.....

As a sulfhydrly protease, Papain has a catalytic site with three important residues--Cysteine-25, Histidine-159,and Asparganine176. The

References

1. Kamphuis, I. G., Kalk, K.H., Swarte, M.B., & Drenth, J (1984). Structure of papain refined at 1.65 A resolution. J. Mol. Biol. 179, 233-56.

2. Lowe, G. The structure and mechanism of action of papain (1970). Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 257, 237-248.

3. PDB (2011). Retrieved November 10, 2011 from http://www.pdb.org/pdb/explore/explore.do?structureId=9PAP

4. PDBsum (2011). Retrieve November 12, 2011 from http://www.ebi.ac.uk/pdbsum/9pap

5. Sathish, Hasige A., Kumar, Parigi Ramesh, & Prakash, Vishweshwaraiah (2009). The differential stability of the left and right domains of papain. Process Biochemistry. 44, 710-16.