Tosyl phenylalanyl chloromethyl ketone

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Tosyl phenylalanyl chloromethyl ketone
Tosyl phenylalanyl chloromethyl ketone.PNG
3D model (JSmol)
ECHA InfoCard 100.006.323
MeSH Tosylphenylalanyl+Chloromethyl+Ketone
Molar mass 351.848 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tosyl phenylalanyl chloromethyl ketone (TPCK) is a protease inhibitor. Its structural formula is 1-chloro-3-tosylamido-4-phenyl-2-butanone.


TPCK is an irreversible inhibitor of chymotrypsin. Also inhibits some cysteine proteases such as caspase, papain, bromelain or ficin.[1] It does not inhibit trypsin or zymogens.

TPCK is observed covalently bound in the active site of Caspase 3 in the crystal structure of the complex solved in 2010.[2] The chloromethyl group reacts with the active site cysteine to form a covalent bond with the loss of the chlorine.

TPCK is chosen for the chemical labelling of active histidine in enzyme analysis. The phenylalanine moiety is bound to the enzyme because of specificity for aromatic amino acid residues at the active site (as in chymotrypsin, in which it binds to the Histidine-57 residue in the active site).[3]


  1. ^ Focus Biomolecules Catalog # 10-2290 TPCK. [1], Retrieved on May 23. 2013.
  2. ^ Ganesan et al. Acta Crystallogr F v67 p 842. PDB Entry 2xyg
  3. ^ Farrell, Shawn O.; Campbell, Mary K. (2006). Biochemistry. Australia: Thomson Brooks/Cole. p. 160. ISBN 0-534-39499-X.