Stomach

The stomach is the first point at which polypeptides are broken down. The low pH of the stomach causes enzymes to denature, opening them up to attack from proteases such as pepsin.

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.

Peptide cutter

If you want to see the effect of the protease pepsin, please enter the amino acid sequence of a polpeptide into the table below.

Why not try the sequence for phenylalanine hydroxylase (PAH); one of the enzymes that we are delivering to the GI tract.

Duodenum

Endopeptidases (trypsin, chymotryopsin, elastase) Exopeptidases (carboxypeptidases A & B) Enteropeptidase

Trypsin

• Trypsin is found in the duodenum and serves to hydrolyse peptides into amino acids.
• Trypsin has an optimal operating pH of ~8 and an optimum temperature of 37°C.
• Trypsin breaks down the milk protein casein. For this reason, milk protein would be a good protein to use for secondary encapsulation.

Chymotryopsin

Elastase

Enterokinase

Carboxypeptidases A & B