The pancreas produces a number of different enzymes for digesting carbohydrates, fats and proteins, and delivers them to the duodenum.
The first group of enzymes are the protein-cleaving enzymes, also called proteases. These include:
The whole group of enzymes dissects proteins from the diet into the smallest constituents, the amino acids. Some enzymes cut off pieces at the end of the amino acid chains, while other enzymes cut between the amino acids in the middle of the chain.
The second group of pancreatic enzymes are enzymes for carbohydrate cleavage. These enzymes include the
These cut long carbohydrate chains, as in bread or pasta, into small sugar molecules so that they can be absorbed into the body.
The last group refers to the lipolytic enzymes that include pancreatic lipase.
These three groups of enzymes therefore cover all three main nutrient components, fats, carbohydrates and proteins, and are absolutely necessary for digestion.
In addition to the enzymes, the pancreas also produces hormones, such as insulin and glucagon, but these are released to the blood and not to the intestine.
One of the pancreatic enzymes is alpha-amylase. Alpha-amylases are an enzyme that breaks down a particular bond in the starch, breaking down carbohydrates into small, multiple or double sugars.
Alpha-amylase is an endo-amylase. It can cut like a pair of scissors in the middle of the molecular chain, not just cutting pieces off the end. This has the advantage that unassailable bonds in branched sugar chains can be easily bypassed. This is also the main difference to the beta-amylases, which can only cut at the ends of the chains. Amylases are produced both in the salivary glands and in the pancreas.
The short sugar chains produced by the amylase can be taken up by the small intestine and used by the body, while long sugar chains are not usable. The highest activity is shown by the alpha-amylase at a pH in the neutral to alkaline range (pH> 7). An increase in alpha-amylases in the blood is a laboratory parameter that serves as a warning for pancreatitis.
Glucosidase is a generic name that refers to all enzymes responsible for the degradation of sugar chains into individual sugar molecules. These sit in humans especially on the intestinal mucosa. Glucosidase inhibitors can be used as blood sugar lowering drugs in type 2 diabetes mellitus.
After delivery of the lipase into the duodenum, these triacylglycerides break down from the diet. From the triacylglycerols the lipase makes single fatty acids and glycerine. These items can be absorbed and utilized by the intestine. The lipase is inactive without help and needs auxiliary enzymes and calcium to break down the fats.
The auxiliary enzymes are produced by the pancreas and activated in the intestine. A significant increase in serum lipase, ie lipase in the blood, is a marker of pancreatitis.
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The laboratory value should always be determined if there is a suspicion of pancreatitis, chronic pancreatitis or upper abdominal pain.
Also in other diseases, such as duodenal ulcer, intestinal obstruction or certain infectious diseases, the serum lipase may increase. However, this increase is not as extreme as with acute pancreatitis. Here, the values can increase to eighty times the standard value.
Phospholipases are also among the fat-splitting enzymes. They cut off fatty acids from phospholipids. Phospholipids are complex fats that form an important component of cell membranes.
The phospholipase A separates the fatty acid residues from the carbon atoms one and two. The phospholipase B can split so-called ester bonds.
In addition to the phospholipases A and B, there are also the phospholipases C and D, but these belong to a separate subgroup.
Cholesterol esterase is a hydrolytic (water-soluble) enzyme which, with the aid of water, breaks down the ester bond between the carboxy group of an organic acid and the OH group of a choline. An important example of this class of enzymes is acetylcholinesterase. This splits the messenger acetylcholine into its components and recycles it in the nerve cells. Cholinesterases are mainly produced in the liver and are therefore also a signal for liver damage. They are suitable for long-term control of existing liver diseases.
The Nucleic Acid Splitters Deoxyribonucleases and ribonucleases are enzymes that can cleave DNA and RNA. In humans, among others, the ribonuclease one occurs. This is produced in the pancreas and cleaves the ester bond between a phosphate group and a hydroxyl group.
Since all living things, both plants and animals, store their genetic information in DNA and RNA, these structures are also in our food and must be decomposed by enzymes.
The pancreas also produces protein-cleaving enzymes and their precursors. Proteins refer to all food components that are composed of amino acids. The complete chains of amino acids can not be used by the human body, the amino acids must be cut apart. Trypsin is produced as a precursor in the pancreas and released to protect the pancreas together with an inhibitor. Trypsin is an enzyme that cuts particularly well behind basic amino acids.
In addition to its own activity, trypsin can also activate other enzymes. These include chymotrypsin, a serine protease that cleaves particularly aromatic amino acids. Also, the precursor of chymotrypsin is produced in the pancreas and activated only in the intestine.
An increased concentration of chymotrypsin in stool may be an indication of pancreatic disease. Both trypsin and chymotrypsin have their pH optimum in the range of seven to eight and thus in the slightly basic range.
Another enzyme whose precursor is produced in the pancreas is elastase. The elastase is also activated by trypsin. It is a protein-splitting enzyme.
The pancreatic elastase is excreted unchanged with the stool after production and can therefore be used as a safe marker for a disease or subfunction of the pancreas. Increased elastase production can lead to lung damage.
Collagen is found in connective tissues of many organisms and can be broken down by collagenases. Collagenases are protein-splitting enzymes, so-called peptidases. In humans, most collagenases are metalloproteases.
These collagenases depend on certain metal ions to perform their function. Some bacteria also have collagenases. In this way, clostridia, for example, can destroy the connective tissue in the intestine.
Kallikrein is a serine protease and thus a protein-splitting enzyme that has many functions in the body. In the blood is a precursor of kallikrein and this has an influence on the blood clotting. Kallikrein also affects the blood pressure and the water and salt balance of the body. Kallikrein is also involved in inflammatory processes. Production takes place in the pancreas, the salivary glands and the kidneys. There are about fifteen types of kallikrein known. Some of these subtypes could also be determined as tumor markers.
Carboxypeptidases are among the protein-cleaving enzymes that are produced in the pancreas. The activation in the intestine is carried out by the enzyme trypsin. After this activation, carboxypeptidases cleave amino acids from the end of the amino acid chains in the diet. Carboxypeptidase A cleaves the amino acid chain to aromatic amino acids and carboxypeptidase B to basic amino acids. Carboxypeptidases thus help to make the proteins in the diet usable by the body.
The enzymes of the pancreas are subject to regulatory circuits of hormones and nerve stimuli of the body. Already thinking of food sets some of these regulatory circuits in motion and the production of digestive enzymes is increased.
The next attraction is the stretching of the stomach as an advance notice that food needs to be digested. The most important stimulating hormones are secretin and cholecystokinin. Secretin promotes the production of pancreatic juice and cholecystokinin the secretion of enzymes. A control from the outside is hardly possible.
Increased production of pancreatic enzymes can have many causes. A particularly strong increase of the enzymes in the blood indicates an acute pancreatitis. Therefore, in cases of unclear upper abdominal pain, these laboratory values should always be considered.
Another possible cause of increased levels is the presence of a benign or malignant pancreatic tumor.
After a completed pancreatitis, narrowed ducts can persist as a long-term consequence and thus continue to increase the pancreatic enzymes. Other serious diseases of the gastrointestinal tract can increase these laboratory values. Which includes :
Certain medications can also increase certain enzymes. Heparin, opiates, antibiotics and also the anti-baby pill have an influence on enzyme production. Altered laboratory values should always be discussed with the attending physician.
A decreased amount of pancreatic enzymes is equivalent to a pancreatic hypofunction. Through a chronic inflammation of the pancreas, the ability to produce enzymes can be limited over a longer course. The function of the gland may also be weakened by malignant tumors in the pancreas.
A genetic cause can be the cystic fibrosis. Most commonly known as pulmonary disease, pancreatic secretion also affects the pancreas. Such hypofunction is often manifested by indigestion. However, these symptoms usually only appear when the function of the pancreas falls below ten percent of normal performance. The therapy is usually limited to a special therapy.