Description

• Application: Pepsin from Sigma has been used along with other enzymes for the determination of enzyme-resistant starch (RS) in bread.[1] It has also been used to simulate in vitro gastrointestinal digestion of pea or whey protein isolates.[2]
• 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.[4] Z-L-tyrosyl-L-phenylalanine, Z-L-glutamyl-L-tyrosine, or Z-L-methionyl-L-tyrosine may be used as substrates for pepsin digestion.[4][5] Pepsin is inhibited by several phenylalanine-containing peptides.[6]
• 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.)
• 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.
• Other Notes: View more information on pepsin at www.sigma-aldrich.com/enzymeexplorer.