Sandbox 37: Difference between revisions
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==Mechanism== | ==Mechanism== | ||
[[Image:Papain mechanism.jpg | right| thumb| Mechanism of papain catalysis]] | [[Image:Papain mechanism.jpg | right| thumb| Mechanism of papain catalysis]] | ||
Papain cleaves peptide bonds of basic amino acids, leucine, or glycine. It also hydrolyzes esters and amides.<ref>http://www.sigmaaldrich.com/life-science/metabolomics/enzyme-explorer/analytical-enzymes/papain.html</ref> Its mechanism of breaking peptide bonds takes place in its <scene name='Sandbox_37/Papain_active_site/1'>active site</scene>. The active site contains a catalytic diad of residues cysteine-25 and histidine-159. The asparagine-175 residue helps with orientation during catalysis. His-159 deprotonates cys-25, then cys-25 attacks the carbonyl of the peptide as a nucleophile. A water molecule then deacylates the enzyme and releases the peptide. | |||
<scene name='Sandbox_37/Papain_active_site/1'>active site</scene> | |||
==Function== | ==Function== | ||
==Inhibition== | ==Inhibition== | ||
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<ref>http://www.pdb.org/pdb/explore/remediatedSequence.do?structureId=1POP¶ms.chainEntityStrategyStr=all</ref> | <ref>http://www.pdb.org/pdb/explore/remediatedSequence.do?structureId=1POP¶ms.chainEntityStrategyStr=all</ref> | ||
<ref>http://en.wikipedia.org/wiki/Papain</ref> | <ref>http://en.wikipedia.org/wiki/Papain</ref> | ||
==References== | ==References== | ||
<references /> | <references /> | ||
