Proteolytic enzymes (synonym: proteases) are proteins, peptide hydrolases, enzymes of the hydrolase class, the main peptide bonds between amino acids in proteins and peptides.
Proteolytic enzymes play an important role in altering food proteins in the human stomach and intestines. Most proteolytic enzymes in the digestive system are produced as proenzymes. The physiological meaning of this lies in the fact that the act of production of an enzyme (proenzyme) was separated from the act of its activation – transformation in the enzyme and, thus, protein tissues producing enzymes did not affect the last enzymes themselves.
Classification of proteolytic enzymes
Proteases are divided into:
- exopeptidases (peptidases) that hydrolyze (cleave), predominantly, external peptide bonds in proteins and peptides
- endopeptidases (proteinases), hydrolyzing, mainly, internal peptide bonds
Endopeptidases include the most important proteolytic enzymes for gastric digestion, pepsin, gastrixin, and chymosin, as well as trypsin, chymotrypsin, and elastase, produced as proenzymes by the pancreas and involved in intestinal digestion.
Exopeptidases are the proteolytic enzymes carboxypeptidase A and carboxypeptidase B, also present in pancreatic juice. Exopeptidases include intestinal juice enzymes: aminopeptidases (alanine aminopeptidase and leucine aminopeptidase) and dipeptidases (glycylglycine dipeptidase, glycilleucine dipeptidase, prolinase and prolidase).
Proteases are divided into six groups, depending on the structure of the active site:
- serine; serine is present in the active center of these proteases; serine proteases – trypsin,
- chymotrypsin and elastase account for 44% of the total protein of the exocrine pancreas
- aspartyl – gastric proteases pepsin, gastrixin, catapepsins D and E and others
- metalloproteases – for example, carboxypeptidases A and B are Zn-metalloproteases
Proteolytic enzymes in drugs
Proteolytic enzymes (proteases) are active components in many enzyme preparations used to correct gastric secretory dysfunction and digestive disorders in the small intestine.
The first type of drugs containing proteolytic enzymes are extracts of the gastric mucosa, the main active ingredient of which is pepsin. He, as well as other peptidases contained in the gastric mucosa, break down almost all natural proteins. These drugs are used primarily for gastritis with low acidity and are not recommended for the treatment of diseases of the gastrointestinal tract with high acidity.
The second type of drugs containing proteolytic enzymes are complex preparations containing the main pancreatic enzymes of domestic animals. Such drugs contribute to the relief of clinical signs of exocrine pancreatic insufficiency, which include decreased appetite, nausea, rumbling in the abdomen, flatulence, steatorrhea, creatorrhoea and amylorrhea. The most popular drug containing a complex of pancreatic enzymes, including proteases, is pancreatin.
Proteolytic enzymes are also used in medicines intended for the treatment of burns, bedsores, trophic ulcers, purulent wounds, purulent otitis media, sinusitis and bronchopulmonary diseases. An example of such a drug is the enzyme preparation Chymopsin, which contains a mixture of trypsin and chymotrypsin as a combined active substance.
Proteases – Food Supplements
Protease (Proteases) is registered as a food additive with the international code E1104. The official list of food additives specifies 4 types of proteolytic enzymes that are classified as food additives: (i) protease, (ii) papain, (iii) bromelain, (iv) ficin. The use of proteases in this capacity is flour improvers and bread stabilizers, meat and fish maturation accelerators, flavor and aroma enhancers.