Sandbox 31: Difference between revisions
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The <scene name='Sandbox_31/Hydrophobic_residues/2'>Hydrophobic Residues</scene> in papain are primarily located toward the inside of the enzyme or paired by hydrophobic interactions with other hydrophobic residues to exclude water. The <scene name='Sandbox_31/Charged/2'>Polar Residues</scene> are located facing the exterior, in the active site, or paired with other charged residues. The charged and polar residues are hydrophilic therefore do not orient themselves to exclude water or solvent. The charged <scene name='Sandbox_31/Termini/4'>Termini</scene> face outward due to their hydrophilic nature. | The <scene name='Sandbox_31/Hydrophobic_residues/2'>Hydrophobic Residues</scene> in papain are primarily located toward the inside of the enzyme or paired by hydrophobic interactions with other hydrophobic residues to exclude water. The <scene name='Sandbox_31/Charged/2'>Polar Residues</scene> are located facing the exterior, in the active site, or paired with other charged residues. The charged and polar residues are hydrophilic therefore do not orient themselves to exclude water or solvent. The charged <scene name='Sandbox_31/Termini/4'>Termini</scene> face outward due to their hydrophilic nature. | ||
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<scene name='Sandbox_31/1popligand_contacts/1'>TextToBeDisplayed</scene> | <scene name='Sandbox_31/1popligand_contacts/1'>TextToBeDisplayed</scene> | ||
</StructureSection> | |||
==Active Site and Mechanism== | |||
The active site of papain has a <scene name='Sandbox_31/Activesite/1'>"Catalytic Triad"</scene>including CYS 25, HIS 159, and ASN 175. | |||
[[Image:papain2.jpg]] | |||
This triad interacts with the substrate to catalyze the reaction. The sulfur from CYS 25 attacks the backbone amine on the substrate forming a tetrahedral intermediate. Next, the carbonyl is reformed and the carbon nitrogen bond is broken. A water associated with a nitrogen on HIS 159 then attacks the carbonyl forming a second tetrahedral intermediate. The carbonyl then reforms breaking the carbon-sulfur bond. This leaves a carboxy group on the end of one piece of the substrate and an amino group on the end of the other piece. | |||
==References== | ==References== | ||
