Sandbox 32
From Proteopedia
| Line 17: | Line 17: | ||
=='''Inhibition'''== | =='''Inhibition'''== | ||
| - | Papain is inactivated by oxygen iodine, hydrogen peroxide, and EDTA (3). Also, it is is irreversibly inhibited by N-ethylmaleimide and iodoacetate. Other inhibitors of Papain are <scene name='Sandbox_32/Khq/1'>ZLFG </scene> and <scene name='Sandbox_32/Inhibition/1'>ICP</scene> (inhibitor of cysteine protease) (1). | + | Papain is inactivated by oxygen iodine, hydrogen peroxide, and EDTA (3). Also, it is is irreversibly inhibited by N-ethylmaleimide and iodoacetate. Other inhibitors of Papain are <scene name='Sandbox_32/Khq/1'>ZLFG </scene> and <scene name='Sandbox_32/Inhibition/1'>ICP</scene> (inhibitor of cysteine protease) (1). With ZLFG, the methylene carbon will covalently bind to the cysteine-25 carbon and the hydrophobic pocket near the active site will also be inhibited (1). |
| - | |||
| - | |||
| - | The sulfhydryl protease contains many <scene name='Sandbox_32/hydrophobic residues/1'>hydrophobic residues</scene>. There are also a few <scene name='Sandbox_32/Negatively_charged_residues/1'> negatively charged</scene>residues and no positively charged residues except for histidine. Along with these hydrophobic/hydrophillic interactions, <scene name='Sandbox_32/disulfide_bonds/3'>disulfide bonds </scene> 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 | ||
| - | |||
| - | |||
| - | <scene name='Sandbox_32/Hydrophobic/1'>hydrophobic and charged residues </scene> | ||
| - | |||
| - | |||
| - | |||
| - | <scene name='Sandbox_32/Inhibition/1'>TextToBeDisplayed</scene> | ||
| - | <scene name='Sandbox_32/Khq/1'>TextToBeDisplayed</scene> | ||
| - | |||
| - | <scene name='Sandbox_32/Khg/1'>TextToBeDisplayed</scene> | ||
<scene name='Sandbox_32/Hmmmmmmmmmmm/1'>TextToBeDisplayed</scene> | <scene name='Sandbox_32/Hmmmmmmmmmmm/1'>TextToBeDisplayed</scene> | ||
| - | |||
| - | |||
| - | |||
| - | |||
| - | |||
| - | |||
| - | |||
=='''References'''== | =='''References'''== | ||
Revision as of 07:07, 14 November 2011
| Please do NOT make changes to this Sandbox. Sandboxes 30-60 are reserved for use by Biochemistry 410 & 412 at Messiah College taught by Dr. Hannah Tims during Fall 2012 and Spring 2013. |
Contents |
Introduction
|
Papain is a sulfhydryl 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 composed of a single amino acid chain. The structure shown is of 1.65Å resolution (2).
Structure
Papain contains 212 amino acid resiudes and a molecular weight of 23.4 kDa (5). It's secondary structure contains 7 that make up 25% of the protein, and 17 making up about 17% (4).
In its 3D structure, Papain is stabilized by many These interactions have been shown to be very important in the overall structure and folding of the protein (6). The are also shown along with both . In addition, 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 . There are 6 cysteine residues that make up these bonds--Cys 22-63, 56-95, 153-200 (4).
Catalytic Mechanism
As a sulfhydryl protease, Papain has a catalytic site with three important residues --Cysteine-25, Histidine-159,and Asparganine176 (3). The catalytic site is located in the between the L and R domains of the protein The centers around Cysteine-25 as it is a sulfhydryl protease. Sulfur on the cysteine will nucelophilicaly attack its substrate. Histidine acts to accept a proton from sulfur, allowing it to be negatively charged. In the oxyanion hole, asparganine stabilizes the rest of the protein, substrate molecule.
Inhibition
Papain is inactivated by oxygen iodine, hydrogen peroxide, and EDTA (3). Also, it is is irreversibly inhibited by N-ethylmaleimide and iodoacetate. Other inhibitors of Papain are and (inhibitor of cysteine protease) (1). With ZLFG, the methylene carbon will covalently bind to the cysteine-25 carbon and the hydrophobic pocket near the active site will also be inhibited (1).
References
1. Alphey, Magnus S. & Hunter, William N. (2006). High-resolution complex of papain with remnants of a cysteine protease inhibitor derived from Trypanosoma brucei. Crystallography, 62, 504-508.
2. 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.
3. 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.
4. PDB (2011). Retrieved November 10, 2011 from http://www.pdb.org/pdb/explore/explore.do?structureId=9PAP
5. PDBsum (2011). Retrieve November 12, 2011 from http://www.ebi.ac.uk/pdbsum/9pap
6. 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.
