Sandbox 39: Difference between revisions
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Papain has a broad specificity for protein substrates. The active site consists of seven subsites (S1-S4 and S1’-S3’) that can each accommodate one amino acid residue of a protein substrate (P1-P4 and P1’-P3’). | Papain has a broad specificity for protein substrates. The active site consists of seven subsites (S1-S4 and S1’-S3’) that can each accommodate one amino acid residue of a protein substrate (P1-P4 and P1’-P3’). | ||
[[Image:Subsites.jpg|right]] | [[Image:Subsites.jpg|right]] | ||
<ref>Image from: | |||
Hans-Hartwig Otto, and Tanja Schirmeister (1997) Cysteine Proteases and Their Inhibitors. Chemical Reviews. No. 97, 133-171.</ref>]] | |||
Specificity is controlled, however, by the <scene name='Sandbox_39/Catalytic_triad/2'>catalytic triad</scene>, a hydrophobic pocket that accommodates the side chains of the protein substrate. This triad consists of a histidine, asparagine, and a cysteine, after which the protein is categorized as a cysteine protease. Papain exhibits specific substrate preferences for hydrophobic or aromatic residues. | Specificity is controlled, however, by the <scene name='Sandbox_39/Catalytic_triad/2'>catalytic triad</scene>, a hydrophobic pocket that accommodates the side chains of the protein substrate. This triad consists of a histidine, asparagine, and a cysteine, after which the protein is categorized as a cysteine protease. Papain exhibits specific substrate preferences for hydrophobic or aromatic residues. | ||
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== Hydrogen Bonding == | == Hydrogen Bonding == | ||
Hydrogen bonds are essential for the stability of a protein. In | Hydrogen bonds are essential for the stability of a protein. In the image shown at the left, the hydrogen bonds can be seen between the secondary structures of the protein as white, dashed lines. Papain contains very specific hydrogen bonding between the amino acid residues. This representation clearly shows how crucial hydrogen bonding is to help maintain the stability of the protein. | ||
[[Image:Hbonds.jpg]] | |||
ref>Image from: | |||
http://www.rcsb.org/pdb/explore/jmol.do?structureId=9PAP&bionumber=1</ref>]] | |||
== Papain Inhibition == | == Papain Inhibition == | ||
