Pepsin is an enzyme in the stomach that begins the digestion of proteins by splitting them into smaller pieces. It is a gastric protease; pepsin is secreted in an inactive form, pepsinogen, which is activated by stomach acid. enzyme produced in the mucosal lining of the stomach that acts to degrade protein.
Pepsin is one of three principal protein-degrading, or proteolytic, enzymes in the digestive system, the other two being chymotrypsin and trypsin . The three enzymes were among the first to be isolated in crystalline form. During the process of digestion, these enzymes, each of which is particularly effective in severing 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. In the laboratory studies it is most efficient in cleaving bonds involving the aromatic amino acids, phenylalanine, tryptophan, and tyrosine. Pepsin is synthesized in an inactive form by the stomach lining; hydrochloric acid, also produced by the gastric mucosa, is necessary to convert the inactive enzyme and to maintain the optimum acidity ( pH 1-3) for pepsin function. Pepsin and other proteolytic enzymes are used in the laboratory analysis of various proteins; pepsin is also used in the preparation of cheese and other protein-containing foods.
This chemical is expressed as a pro-form, pepsinogen with an additional 44 amino acids, which are cleaved off outside the secreting cell, to avoid digestion of cellular proteins.
It is most active at pH 2-4. It is permanently inactivated above pH 6.
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Synonyms: Pepsinum; Puerzym
CAS No.: 9001-75-6
Molecular Weight: 34500
Pepsin research information
Effects of antacids on pepsin - Antacids do just what their name suggests: they neutralize the normal stomach acid (HCl), causing the pH to rise to a nearly neutral pH of around 6 to 7. As the pH rises above 4, pepsin activity decreases or stops. Some types of antacids, made of sodium bicarbonate (NaHCO3) or calcium carbonate (CaCO3), are easily absorbed into a person's body and can cause a pH imbalance, possibly leading to kidney damage or other problems.
Pepsinogens and pepsins - Pepsinogens are secreted in a form such that the activation peptide assumes a compact structure that occludes the active site. On exposure to an acidic (pH < 4) environment such as occurs in the lumen of the stomach, the activation peptide unfolds, allowing the active site to clip it off, yielding mature, catalytically active pepsin.
Albumen and pepsin - Pepsin is a protease enzyme, which is found in your stomach. It digests protein like albumen egg. The effect of temperature on an enzyme reaction. The effect of pH on an enzyme reaction.
PDB Molecular illustrations - Pepsin uses a pair of aspartate residues to perform the protein cleavage reaction. In an example of parallel evolution (where two organisms independently develop the same method for solving a problem).
Characteristics of pepsin from porcine stomach - Conversion of pepsinogen to pepsin, which involves releasing a peptide, may be an autocatalytic process involving self-cleavage by the zymogen. Al-JanabiJanabi et al. (1972) indicate the activation to be intermolecular above pH 4. Anderson and Harthill (1973) report that peptides released on activation have pepsin inhibitory activity.
Cleansing The Small Intestine - Certain foods, such as pasteurized milk and many cooked foods, cause the mucus buildup on the wall of the small intestine (raw foods do not cause this mucus buildup). The mucus coats the villi on the wall of the small intestine.
Enzymes - Provides an introduction, for the uninitiated, to enzymes and how they function.