As an enzyme of the pancreas, trypsin is responsible for the further breakdown of food proteins. It exerts its effect in the highly alkaline range. Trypsin deficiency leads to protein deficiency in the body due to impaired protein breakdown.
What is trypsin?
Trypsin represents a protease that continues the digestion of proteins in the alkaline region of the small intestine. In the stomach, protein cleavage already begins in the acidic environment by the enzyme pepsin. The enzyme trypsin consists of three components. These are trypsin-1 as a cation, trypsin-2 as an anion and trypsin-4. Two-thirds of the enzyme consists of trypsin-1 and one-third of trypsin-2. Trypsin-4 or mesotrypsin is present only in minor amounts. Trypsin is an endoprotease. It cleaves a protein only at specific sites. Furthermore, it is a serine protease. Its active site contains the catalytic triad of aspartic acid, histidine and serine. It cleaves dietary proteins preferentially at the basic amino acids lysine, arginine and modified cysteine. Trypsin is produced from the zymogen precursor trypsinogen with the aid of the catalytic action of the intestinal enzyme enteropeptidase. The enzyme consists of 224 amino acids. Trypsin exerts its optimal effect at a pH of 7 to 8.
Function, action, and tasks
The task of trypsin is to continue the breakdown of proteins, which has already begun in the stomach, now in the alkaline range. In the stomach, predigestion of dietary proteins by the similar enzyme pepsin begins in the acidic range. Here, too, the protein chains are broken up at specific points. While this breakdown of proteins in the stomach takes place at aromatic amino acids such as phenylalanine, the proteins and polypeptides are broken down by trypsin at the basic amino acids lysine and arginine and at modified cysteine. Another difference to pepsin is that trypsin exerts its optimum effect in the alkaline range at a pH of 7 to 8. Activated trypsin also converts other zymogens such as chymotrypsinogen, pro-elastase, procarboxypeptidase and other inactive enzymes into active enzymes. The conversion starts immediately after the release of trypsin. The other pancreatic proteases are chymotrypsin, carboxypeptidase or elastin. Furthermore, trypsin also activates itself by converting trypsinogen. The pancreatic enzymes are initially present in their inactive form to prevent the pancreas from decomposing by self-digestion. Only when the inactive preforms are secreted can their activation occur by cleavage. First, enteropeptidase catalyzes the conversion of trypsinogen to trypsin. This is the sole function of enteropeptidase. In this process, a hexamer containing the terminal amino acid lysine is cleaved from trypsinogen. Since trypsin also cleaves polypeptide chains at the basic lysine, it now also catalyzes its own activation and simultaneously the activation of the other zymogens. Together with the enzymes chymotrypsin and elastase, it cleaves larger proteins in the small intestine and the peptones (polypeptide chains) formed by the action of pepsin into tri- and dipeptides. These smaller peptides then undergo further breakdown into amino acids with the help of other enzymes. Specifically, trypsin also contributes to the breakdown of the amino acid methionine. Lysine, among other things, stimulates the formation of trypsin.
Formation, occurrence, properties, and optimal values
Trypsin is an endogenous enzyme for the digestion of food proteins. That is why it is always secreted by the pancreas shortly after food ingestion. However, the enzyme can also be obtained from animal sources and used medicinally. The protein-cleaving effect can be used, among other things, to break down the body’s own protein complexes. In this way, immune complexes can be broken down in autoimmune diseases. Inflammations in the musculoskeletal system can also be treated well with trypsin. Furthermore, it activates the enzyme plasmin from plasminogen. Plasmin dissolves fibrin in the event of severe thrombus formation. Thus, with the help of trypsin, thrombosis can be treated or even prevented. Furthermore, trypsin aids digestion when taken during meals. When applied 1 to 2 hours before or after a meal, it exerts its anti-inflammatory effect.
Diseases and disorders
In the context of pancreatic insufficiency, the synthesis of digestive enzymes such as trypsin may be limited. The result is the development of digestive disorders.In addition to proteases, the pancreas also produces lipases and amylases. If the enzymes are missing, the food components are no longer digested and enter the colon in the process. If trypsin is missing, for example, the food proteins can no longer be properly broken down. Putrefactive bacteria settle in the colon and break down the proteins anaerobically. This leads to massive digestive problems with flatulence, diarrhea and abdominal pain. Furthermore, the reduced formation of amino acids leads to protein deficiency and malnutrition despite sufficient food intake. However, the enzymes can also be supplied externally. However, there are also medical emergencies in which endogenous enzymes such as trypsin digest the pancreas itself. This can happen in the event of an obstruction of the bile and pancreatic ducts. In this case, trypsin is released but cannot enter the small intestine due to the pancreatic obstruction. If the pancreatic duct is not opened in this acute emergency situation, a fatal outcome occurs due to self-dissolution of the pancreas. The pancreatic duct may also be completely or partially obstructed in pancreatic tumors. The action of digestive juices within the pancreas manifests as chronic or acute pancreatitis. A deficiency of trypsin can also be caused by a mutation. Furthermore, there are also hereditary forms of pancreatitis when the breakdown of trypsin is impaired.