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Ann Taylor sandbox 14

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The catalytic triad is His 57, Ser 195 and Asp 102.
The catalytic triad is His 57, Ser 195 and Asp 102.
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Revision as of 14:55, 19 February 2010

The Mechanism of Trypsin

The reaction involves the nucleophilic attack of the active site Ser on the carbonyl carbon atom of the scissile peptide bond to form the tetrahedral intermediate. The histidine-H makes Ser-OH more nucleophilic.

PDB ID 2age

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2age, resolution 1.15Å ()
Ligands:
Non-Standard Residues:
Activity: Trypsin, with EC number 3.4.21.4
Related: 2agg, 2agi, 2ah4


Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml


The decomposition of the tetrahedral intermediate to the acyl-enzyme intermediate through general acid catalysis by the active site Asp-polarized His (the His-H loses its H to the leaving amine); loss of the amine product and its replacement by a water molecule (new H-bond with histidine); the reversal of Step 2 to form a second tetrahedral intermediate (OH now bonded to cleaved carbonyl carbon and H bonded to histidine); and the reversal of Step 1 to yield the reaction’s carboxyl product and the active enzyme (electron pushing shoves off serine and the H-bond from His).

This PDB code is 2age. [1]

It leaves the pancreas and is activated by endopeptidase and then is autocatalytic after that point, activating itself in the duodenum. After catalysis, the enzyme is changed and then restored to its original state by water.

The catalytic triad is His 57, Ser 195 and Asp 102.

  1. ↑ Radisky ES, Lee JM, Lu CJ, Koshland DE Jr. Insights into the serine protease mechanism from atomic resolution structures of trypsin reaction intermediates. Proc Natl Acad Sci U S A. 2006 May 2;103(18):6835-40. Epub 2006 Apr 24. PMID:16636277

Proteopedia Page Contributors and Editors (what is this?)

Sayan Paria, Ann Taylor

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