Produced by stomach cells and mucus cells found in the stomach gland. Pepsin is found in the stomach, and it breaks down large proteins into smaller polypeptides that can be absorbed into the intestines. When large proteins enter the intestines, it causes inflammation and different diseases.
Pepsin has about a 90% maximum activity at a pH of 1.5 and a temperature range of 98˚F to 107˚F.
The substrate for pepsin is protein. Pepsin produces large polypeptides as it breaks down the gigantic ones that are to big to fit in intestines.