Description

• 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.[1]
• 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+.
• Unit Definition: One unit will hydrolyze 1.0 μmole of BTEE per min at pH 7.8 at 25 °C.
• Preparation Note: TLCK treatment inactivates trypsin which may be present in chymotrypsin, without affecting the chymotrypsin activity.
• Analysis Note: Protein determined by A1%/280
• Other Notes: View more information on chymotrypsin at www.sigma-aldrich.com/enzymeexplorer