Sandbox Reserved 918: Difference between revisions

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These substrates, along with many others, are cleaved by DPP IV at its active site containing a [http://en.wikipedia.org/wiki/Catalytic_triad catalytic triad] composed of <scene name='57/573132/1x70_catalytictriad/1'>Ser630, His740, and Asp708</scene>. This Serine-Histadine-Asparatate motif, best known in the enzyme [http://en.wikipedia.org/wiki/Chymotrypsin chymotrypsin], uses acid-base chemistry to facilitate the binding, cleaving, and release of the given substrate. The mechanism of the reaction is as follows:  
These substrates, along with many others, are cleaved by DPP IV at its active site containing a [http://en.wikipedia.org/wiki/Catalytic_triad catalytic triad] composed of <scene name='57/573132/1x70_catalytictriad/1'>Ser630, His740, and Asp708</scene>. This Serine-Histadine-Asparatate motif, best known in the enzyme [http://en.wikipedia.org/wiki/Chymotrypsin chymotrypsin], uses acid-base chemistry to facilitate the binding, cleaving, and release of the given substrate. The mechanism of the reaction is as follows:  


[[Image:Serine_protease_mechanism_by_snellios.png|right|thumb|150px|<font size=".8"><div style="text-align: center;"> Arrow Pushing Mechanism  </div></font>]]
<div style="text-align: left;">
# Substrate binds to enzyme and carbonyl carbon is positioned by active site.
# Histadine, via hydrogen bond with asparatate, becomes more electronegative and therefore readily accepts the hydrogen from the -OH group on serine, making it nucleophilic. [[Image:Serine_protease_mechanism_by_snellios.png|right|thumb|150px|<font size=".8"><div style="text-align: center;"> Arrow Pushing Mechanism  </div></font>]]
# The nucleophilic serine attacks the carbonyl carbon, generating a tetrahedral intermediate (as seen in the [[arrow pushing mechanism).
# The peptide bond is cleaved and the electrons from it move to attack the hydrogen on the histadine. This half of the substrate now dissociates, leaving the other half still bound to serine.
# Histadine then deprotonates a water molecule, forming a nucleophilic hydroxyl group that attacks the serine-bound carbonyl carbon.
# As the electrons move from the oxygen back down to reform the double bond, serine dissociates as a leaving group and the other half of the substrate dissociates from the enzyme.
# The negative oxygen on serine readily accepts the hydrogen from histadine and in doing so regenerates the active site of the enzyme.
</div>


<font size=".1">
# Substrate binds to enzyme and carbonyl carbon is positioned by active site.
# Histadine, via hydrogen bond with asparatate, becomes more electronegative and therefore readily accepts the hydrogen from the -OH group on serine, making it nucleophilic.
# The nucleophilic serine attacks the carbonyl carbon, generating a tetrahedral intermediate (as seen in the arrow pushing mechanism).
# The peptide bond is cleaved and the electrons from it move to attack the hydrogen on the histadine. This half of the substrate now dissociates, leaving the other half still bound to serine.
# Histadine then deprotonates a water molecule, forming a nucleophilic hydroxyl group that attacks the serine-bound carbonyl carbon. As the electrons move from the oxygen back down to reform the double bond, serine dissociates as a leaving group and the other half of the substrate dissociates from the enzyme.
# The negative oxygen on serine readily accepts the hydrogen from histadine and in doing so regenerates the active site of the enzyme. </font>
</StructureSection>
</StructureSection>


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