Analysis Note

Optimum pH is 2-4. Active in 4 M urea and 3 M guanidine HCl. Stable at 60 °C. Pepsin is irreversibly inactivated at pH 8.0 - 8.5.

Protein determined by E1%/280

E1%/280=14.7

Application

Pepsin cleavage can be used to produce F(ab′)₂ fragments of antibodies. pepsin at www.sigma-aldrich.com/enzymeexplorer.

The enzyme from Sigma has been used in the digestion of crude wheat gliadin. It has been used along with other enzymes to demonstrate the effects of fixation and enzymatic digestion in immunohistochemical assays, using paraffin embedded tissue. It has been used for digestion (before using immunoperoxidase techniques) to reduce non-specific background staining in sections of bronchial tissues. The enzyme has also been used in the preparation of F(ab)₂ fragment from IgG.

Pepsin is a peptidase used to digest proteins and is commonly used in the preparation of Fab fragments from antibodies. Pepsin, from porcine gastric mucosa, has been used to hydrolyze dry cervical samples in mice.

Biochem/physiol Actions

The enzyme does not cleave at valine, alanine, or glycine linkages. Z-L-tyrosyl-L-phenylalanine, Z-L-glutamyl-L-tyrosine, or Z-L-methionyl-L-tyrosine may be used as substrates for pepsin digestion. Pepsin is inhibited by several phenylalanine-containing peptides.

Preferential cleavage: hydrophobic and aromatic residues in P1 and P1′ postitions. Cleaves Phe-Val, Gln-His, Glu-Ala, Ala-Leu, Leu-Tyr, Tyr-Leu, Gly-Phe, Phe-Phe and Phe-Tyr bonds in the β chain of insulin

Pepsin hydrolyzes peptide bonds, not amide or ester linkages. Pepsin cleaves peptides with an aromatic acid on either side of the peptide bond. Sulfur-containing amino acids increase susceptibility to hydrolysis when they are close to the peptide bond. Pepsin preferentially cleaves at the carboxyl side of phenylalanine and leucine and at the carboxyl side of glutamic acid residues. Cleaves Phe-Val, Gln-His, Glu-Ala, Ala-Leu, Leu-Tyr, Tyr-Leu, Gly-Phe, Phe-Phe and Phe-Tyr bonds in the β chain of insulin Pepsin is the major proteolytic enzyme produced in the stomach. It digests proteins through the cleavage of interior peptide linkages.

Other Notes

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

Packaging

1, 5, 10, 25, 100 g in poly bottle

250 mg in poly bottle

Unit Definition

One unit will produce a δA₂₈₀ of 0.001 per min at pH 2.0 at 37°C, measured as TCA-soluble products using hemoglobin as substrate. (Final volume = 16mL. Light path = 1cm.)