Suatu enzim yang mengurakan protein. Terdapat dalam getah lambung, pepsin memerlukan suasana asam untuk dapat berfungsi. Dalam getah lambung terdapat asam klorat (HCl) yang memberikan suasana asam bagi pepsin.
Merriam-Webster Online Dictionarypepsin
a protease of the stomach that breaks down most proteins to polypeptides
a preparation containing pepsin that is obtained from the stomach especially of the hog and is used especially as a digestive aid
Pepsin is an enzyme that breaks down proteins into smaller peptides (that is, a protease). It is produced in the stomach and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pepsin has three dimensional structure, of which one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, or the location on the enzyme where the substrate binds and the reaction takes place
It is one of three principal proteases in the human digestive system, the other two being chymotrypsin and trypsin. During the process of digestion, these enzymes, each of which is specialized in severing links between particular types of amino acids, collaborate to break down dietary proteins into their components, i.e., peptides and amino acids, which can be readily absorbed by the small intestine. Pepsin is most efficient in cleaving peptide bonds between hydrophobic and preferably aromatic amino acids such as phenylalanine, tryptophan, and tyrosine.
Pepsin's proenzyme, pepsinogen, is released by the chief cells in the stomach wall, and upon mixing with the hydrochloric acid of the gastric juice, pepsinogen activates to become pepsin. Pepsin is an aspartic protease, using a catalytic aspartate in its active site.