Pepsin

• Released by chief cells in the stomach.

• Expressed as a zymogen pepsinogen.

• Pepsinogen is converted to pepsin by HCl which is released by parietal cells of the stomach.

• Cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine.

• Optimum pH of 1.5 to 2. Pepsin denatures when the pH is more than 5.0.

Duodenum = Endopeptidases (trypsin, chymotryopsin, elastase)

Exopeptidases (carboxypeptidases A & B)

Enteropeptidase

Small Intestine = Aminopeptidase N

Dipeptidyl aminopeptidase IV

Aminopeptidase P

Carboxypeptidase P

Angotensin-converting enzyme

Glutamyl aminopeptidase