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

Application

Pepsin from Sigma has been used along with other enzymes for the determination of enzyme-resistant starch (RS) in bread. It has also been used to simulate in vitro gastrointestinal digestion of pea or whey protein isolates.

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

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. Product P6887 is provided as a lyophilized powder and has been used to digest protein during dietary fiber analysis.

Biochem/physiol Actions

Unlike many other peptidases, pepsin hydrolyzes only peptide bonds, not amide or ester linkages. The cleavage specificity includes peptides with an aromatic acid on either side of the peptide bond, especially if the other residue is also an aromatic or a dicarboxylic amino acid. Increased susceptibility to hydrolysis occurs if there is a sulfur-containing amino acid close to the peptide bond, which has an aromatic amino acid. Pepsin will also preferentially cleave at the carboxyl side of phenylalanine and leucine, and to a lesser extent at the carboxyl side of glutamic acid residues. It 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

Other Notes

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

Packaging

250 mg in glass bottle

1, 5, 10 g in glass 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 = 16 ml. Light path = 1 cm.)