Human Digestive Proteases:

The stomach serves to break large proteins into peptides. These peptides are then broken down into amino acids once they enter the duodenum.

Stomach

The stomach is the first point at which polypeptides are broken down. The low pH of the stomach causes enzymes to denature. The process of denaturation opens proteins up to attack from proteases.

Pepsin

Pepsin is a powerful protease that cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine. The optimum pH of pepsin is from 1.5 to 2, at a pH of above 5 denaturation occurs. This means that pepsin is only functional in the acidic environment of the stomach.

One of the enzymes that we are showcasing is phenylalanine hydroxylase (PAH) (as a treatment for PKU). If this enzyme was simply swallowed in an unencapsulated form it would be cleaved in 146 places by pepsin in the stomach.

Click on the perform button to see a simulated digestion of PAH by pepsin. Alternativly, paste in your own sequence to see if it would be a good candidate for encapsulation.