Not available outside of the UK & Ireland.

Analysis Note

Protein determined by A1%/280

Application

α-Chymotrypsin from Sigma has been used to determine the crystal structures of two homologous inhibitors (pars intercerebralis major peptide-C and pars intercerebralis major peptide-D2v) from the insect Locusta migratoria by forming a complex with the enzyme.

Biochem/physiol Actions

α-Chymotrypsin is a serine peptidase and has 241 amino acid residues contained in three polypeptide chains (A chain-13 residues, B chain-131 residues, and C chain-97 residues) linked by disulfide bridges. Molecular weight of this enzyme is found to be 25 kDa. Its pI is 8.75. It selectively hydrolyzes peptide bonds on the C-terminal side of tyrosine, phenylalanine, tryptophan, and leucine. Ca²⁺ activates and stabilizes the enzyme. The enzyme is inhibited by diisopropyl fluorophosphate (DFP), phenylmethanesulfonyl fluoride (PMSF), N-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), chymostatin, aprotinin, α₁-antitrypsin, α₂-macroglobulin, 10 mM Cu²⁺ and Hg²⁺.

A serine protease that hydrolyzes peptide bonds with aromatic or large hydrophobic side chains (Tyr, Trp, Phe, Met, Leu) on the carboxyl end of the bond.

Other Notes

View more information on chymotrypsin at www.sigma-aldrich.com/enzymeexplorer

Packaging

10, 25, 100 mg in glass bottle

Preparation Note

TLCK treatment inactivates trypsin which may be present in chymotrypsin, without affecting the chymotrypsin activity.

Unit Definition

One unit will hydrolyze 1.0 µmole of BTEE per min at pH 7.8 at 25 °C.