α-Chymotrypsin

Absorption

No pharmacokinetic data available.

Toxicity

No toxicokinetic data available.

Chemical properties

Lyophilized powder, dialyzed

The Uses of α-Chymotrypsin

The enzyme from Sigma has been used to assess the effect of limited proteolysis with α-chymotrypsin on the sperm penetration.

The Uses of α-Chymotrypsin

α-Chymotrypsin from bovine has been used in a study to inform proteasome inhibition in order to advance anticancer research. α-Chymotrypsin from bovine has also been used in a study that functionalized surface anchored poly(methylhydrosiloxane) thin films on oxidized silicon wafers.

The Uses of α-Chymotrypsin

α-Chymotrypsin from bovine pancreas has been used in a study to investigate protein extraction by Winsor-III microemulsion systems. α-Chymotrypsin from bovine pancreas has also been used in a study to investigate a new specific fullerene-based fluorescent probe for trypsin.

Indications

No therapeutic indications.

Background

Chymotrypsin (EC 3.4.21.1) is a digestive enzyme that promotes proteolysis, or the breakdown of proteins and polypeptides. It is a serine protease synthesized in the pancreas and is a vital component in the pancreatic juice. Like most proteolytic enzymes, chymotrypsin is activated from its inactive zymogen precursor, chymotrypsinogen, in presence of Trypsin. Chymotrypsin is the most abundant pancreatic proteases that represent up to 10-20% of the total protein synthesized by the exocrine pancreas . Chymotrypsin contains both the catalytic triad and oxyanion hole, and the tertiary structure of chymotrypsin is similar to Trypsin .

General Description

Chymotrypsin (Chymar) is extractedfrom mammalian pancreas and is used in cataractsurgery. A dilute solution is used to irrigate the posteriorchamber of the eye to dissolve the fine filaments that holdthe lens.

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+.

Mechanism of action

The general mechanism for chymotrypsin is the classic serine protease mechanism. Hydrolytic proteolysis by α-chymotrypsin begins with an initial nucleophilic attack on the peptide bond by Ser 195, activated by deprotonation by His 57. This leads to forming a tetrahedral intermediate, stabilized by the amide groups of Ser 195 and Gly 193. The subsequent collapse of this intermediate, assisted by protonation of the leaving group by His 57 and Asp 102, leads to an acyl-enzyme intermediate. Activation of a water molecule by His 57 and Asp 102 facilitates hydrolysis of this intermediate, resulting in the reformation of the catalytically active serine residue and the release of the product facilitated by protonation with His 57.

Pharmacokinetics

Chymotrypsin is a digestive enzyme synthesized in the pancreas that plays an essential role in proteolysis, or the breakdown of proteins and polypeptides. As a component in the pancreatic juice, chymotrypsin aids in the digestion of proteins in the duodenum by preferentially cleaving peptide amide bonds.

Metabolism

No pharmacokinetic data available.

Purification Methods

α-Chymotrypsin is crystallised twice from four-tenths saturated ammonium sulfate solution, then dissolved in 1mM HCl and dialysed against 1mM HCl at 2-4o. The solution is stored at 2o [Lang et al. J Am Chem Soc 80 4923 1958].

References

[1] R J Schilling, A K Mitra. “Degradation of insulin by trypsin and alpha-chymotrypsin.” Pharmaceutical Research 8 6 (1991): 721–7.