Pepsin is the main enzyme produced by the stomach, its function is the digestion of proteins .
Pepsin is initially released in an inactive form, pepsinogen . Only when it comes in contact with hydrochloric acid (HCl) does it become the active form, pepsin. Pepsin acts only in an acidic environment.
Pepsin was discovered in 1835 and its name derives from the Greek ” pepsis ” which means digestion.
The action of pepsin during digestion
Pepsin acts during the chemical digestion of food. At this stage, the food is broken down into smaller parts due to the action of various enzymes present in the digestive juice.
Pepsin is produced by the walls of the stomach . Its action is controlled by gastrin, a hormone that is also produced by the stomach.
When the proteins in the food come into contact with the stomach walls, gastrin stimulates the production of hydrochloric acid, increasing the acidity of the organ to a pH = 2.
The low pH interrupts the digestion of carbohydrates by inactivating the enzyme salivary amylase and denatures proteins, exposing their peptide bonds . Thus, this acidity creates the favorable environment for the performance of pepsin.
Pepsin catalyzes the breakdown of peptide bonds and turns large protein molecules into small peptide chains.
Food can spend up to 4 hours in the stomach under the action of pepsin and other enzymes (amylase and lipase). At the end, the bolus turns into chyme and proceeds to the small intestine .