The enzymes that break down protein include trypsin, chymotrypsin, pepsin, thermolysin, glutamyl endopeptidase, elastase, bromelain and papain. Trypsin, pepsin, elastase, thermolysin, glutamyl, endopeptidase and chymotrypsin are made in the human body. Bromelain comes from pineapples and papain comes from papayas. These enzymes are called proteases.
The enzymes that are made in the body generally break the bonds of long peptide chains and convert them into smaller chains. Large peptide chains are too large to be absorbed through the small intestine, where much of digestion takes place.
Each protease cuts the bonds at a certain point in the peptide chain and each one works best at a certain pH. For example, chymotrypsin does its best work at pH8, which is slightly alkaline. Pepsin works best at pH2, which is extremely acidic. This is because pepsin is released by cells in the stomach, where food is processed in a bath of enzymes and hydrochloric acid. However, trypsin and chymotrypsin are produced in the pancreas and secreted into the small intestine.
Bromelain is found in the fruit and the stem of the pineapple. Bromelian and papain are used as meat tenderizers and as supplements to treat medical conditions such as sports injuries and wounds.