Function
Pepsin is another proteolytic enzyme of the gastric juice, active only in an acidic environment of pH 1.5 to 2.5. It breaks down proteins into intermediate products of digestion called polypeptides. Pepsin is initially secreted as pepsinogen, which is then activated to pepsin by stomach acid.
Uses
Its principal industrial use is together with rennin to help the curdling of milk in the production of cheese. It is given together with other proteolytic enzymes to persons with digestive problems.