|Pepsin is a digestive enzyme found in gastric juice that catalyzes the breakdown of protein to peptides. Pepsin is one of three principal protein-degrading, or proteolytic, enzymes in the digestive system, the other two being chymotrypsin and trypsin. Pepsin is
produced by the walls of the stomach. It requires a strongly acidic environment such as that present in the stomach. Pepsin is most active at pH 2-4 (acidic), pepsin is activated from pepsinogen by hydrochloric acid from the stomach wall. Pepsin (in gastric juice) digests proteins to peptides, 6-12 amino acids long.
Pepsin degrades food proteins in the stomach. In the stomach, the enzyme pepsin functions to break proteins into smaller pieces called polypeptides. It digests large protein molecules into smaller protein molecules (smaller polypeptides). During the process of digestion, pepsin, along with chymotrypsin and trypsin, severe links between particular types of amino acids, collaborate to break down dietary proteins to their components, i.e., peptides and amino acids, which can be readily absorbed by the intestinal lining. Pepsin acts as a potent proteolytic enzyme cleaving proteins into peptides in the gastric lumen at a low pH. Pepsin hydrolyses peptide bonds in the middle of a polypeptide chain. It cleaves the peptide bonds that link consecutive amino-acids in other proteins.
Pepsin adopts a bi-lobal structure with the first 171 amino acids forming one lobe and the subsequent residues forming the other lobe. Pepsin is usually prepared from the stomach of pigs and is the principle digestive component of gastric juice. Pepsin occurs as whit to light yellowish brown powders, or light yellowish brown to brown pastes or liquids. It is odorless or has slight characteristic odors.