PEPSIN- the main proteolytic enzyme of gastric juice (EC 3.4.23.1), belongs to the group of peptide hydrolases, cleaves proteins, mainly to polypeptides, although low molecular weight peptides and amino acids are found among the products of protein cleavage by pepsin. P.'s preparations are used as medicines for substitution therapy for digestive disorders. At nek-ry patol, states P.'s activity in gastric juice (see) is one of diagnostic signs and is defined in clinical and biological laboratories. The content of the proenzyme P. - pepsinogen in the urine (uropepsin) - serves as an additional diagnostic test in the study of the secretory ability of the gastric mucosa. P. finds application in the food and meat and dairy industries.
The item is opened in 1836 by T. Schwann, and in 1930 it is received by Northrop (J. H. Northrop) in a crystal form.
The item is the most well studied representative of a subclass of carboxyl proteinases (see Peptide hydrolases). Mol. weight (mass) P. approx. 35,000, the isoelectric point (see) is at a pH below 1.0, which is due to the high content of aspartic and glutamic acid residues in the enzyme molecule with a low content of diamino acids, as well as the presence of one residue of phosphoric acid. The P. molecule consists of a single polypeptide chain of 327 amino acid residues and is a globule with axes of 5.5 X 4.5 X 3.2 nm, composed of two domains with a similar structure. P.'s molecule is characterized by a very low content of alpha helical sections and a high content of beta structures. Between domains there is a depression, in a cut the P.'s active center is located, it is formed by the amino acid remains localized in different domains; catalytic groups are COOH groups of aspartic acid residues in the 32nd and 215th positions.
P.'s activity, as well as other carboxyl proteinases, is suppressed by diazocarbonyl inhibitors and certain epoxides that specifically block the COOH groups of the active center of the enzyme. P.'s natural inhibitor is pepstatin, an N-substituted pentapeptide produced by certain streptomycetes.
The item is most steady at pH apprx. 5.0-5.5. In a more acidic environment, self-digestion (autolysis) of the enzyme occurs; at pH above 6.0, its rapid and almost irreversible inactivation occurs. The item is inactivated also at a temperature above 60 °.
P. is contained in the gastric juice of mammals, birds, reptiles, and fish. In invertebrates and microorganisms, enzymes similar in properties to P. have been found. In the gastric juice of humans and higher mammals, along with P., gastrixin is present - an enzyme that has properties similar to P. and a homologous structure.
P. is synthesized by the main cells of the glands of the gastric mucosa (see) in the form of an inactive precursor - the pepsinogen proenzyme, which in the presence of hydrochloric acid of gastric juice turns into an active enzyme. In this case, as a result of conformational changes and hydrolysis of the peptide bond between leu44-ile45, a fragment is cleaved off from the N-terminal region of the pepsinogen molecule, and thus. active P. is formed, which then catalyzes the autocatalytic activation of the following portions of the proenzyme. One of the cleaved peptides, the so-called. P.'s inhibitor with a mol. weight (weight) approx. 3000, at pH above 5.0 inhibits the activity of P.; below pH 4.0, the inhibitor is rapidly cleaved. In the urine of mammals, including humans, pepsinogen (uropepsin) is normally found, which penetrates into the urine from the main cells of the gastric mucosa through the blood and kidneys (see Uropepsin).
Process of digestion of proteins in went. - kish. the path begins with the action of P. This enzyme has a wide substrate specificity; it catalyzes the hydrolysis of peptide bonds formed by various amino acid residues in proteins. P. breaks down almost all proteins of plant and animal origin, with the exception of protamines and keratins. P.'s action optimum at pH 2,0. At pH approx. 5.0 P. curdles milk, causing the conversion of caseinogen into casein (see). The item is capable to hydrolyze a number of low-molecular synthetic peptides and esters, aromatic amino acids are a part to-rykh. The optimum for P.'s hydrolysis of many synthetic substrates is at pH 4.0. P. also catalyzes the reaction of trans-peptidation (transfer of an amino acid residue from one synthetic substrate to another).
Commercial preparations of crude P. are obtained from an acid extract (autolysate) of the gastric mucosa by salting out with 15% NaCl solution and subsequent drying. Purified P. is isolated from such preparations using ion-exchange chromatography (see). P.'s analogue - chymosin (see), used in the food industry for cheese making, is obtained in the same way from the mucous membrane of the abomasum - the department of the stomach of cattle. For honey. the purposes apply P. from a mucous membrane of a stomach of pigs. Crystalline P. can be obtained both from commercial P. preparations and from gastric juice or directly from the gastric mucosa.
Many methods are offered for definition of P.'s activity. Previously, the Metta method was used, which, however, is outdated and does not give accurate results. Most often, the Anson method is used to determine P.'s activity - splitting denatured hemoglobin under the influence of P., followed by determination of the amount of tyrosine in a protein-free filtrate (see Anson-Chernikov method). To study P.'s activity in gastric juice and the content of uropepsin in the urine, the Pyatnitsky method is widely used, based on determining the curdling activity of the enzyme.
At a number of diseases went. - kish. a path - hron, gastritis (see), a stomach ulcer and a duodenal ulcer (see. Peptic ulcer), stomach cancer (see) and at nek-ry patol, states - pernicious anemia (see), hypochromic anemia (see. Iron deficiency anemia) P.'s secretion is disturbed. In this regard, P.'s definition in gastric juice, along with the determination of the concentration of hydrochloric acid, has diagnostic value. For diagnostic purposes, the determination of uropepsin in the urine is also used, the content of which is believed to reflect the level of secretory ability of the gastric mucosa.
Pepsin as a drug
The drug P. (Pepsinum), used as a drug, is obtained from the mucous membrane of the stomach of pigs, sucrose or lactose is used as a filler. The drug is a white or cream powder of sweet taste with a specific odor, soluble in water, in 20% ethyl alcohol and insoluble in ether and chloroform.
Usually, P.'s preparations have a rather low proteolytic activity: 1 g of the preparation contains only 5 mg of pure enzyme.
To ensure the optimal effect of the drug, the reaction of the medium in the stomach should be acidic, and the concentration of free hydrochloric acid should not be lower than 0.15-0.2%.
P. apply for substitution therapy for digestive disorders (see), accompanied by secretory insufficiency of the stomach (achilia, hypacid and anacid gastritis, dyspepsia, etc.). It should be borne in mind that endogenous P., like other digestive enzymes, the main cells of the gastric mucosa are usually secreted in excess quantities, so a decrease in the digestive capacity of gastric juice with a decrease in its acidity is often the result of insufficient release of hydrochloric acid, and not a decrease in activity or the intensity of the formation of P. T. o., in hypacid conditions, the provision of optimal conditions for the digestion of gastric contents is of primary importance, and P.'s use is of secondary importance. In anacid conditions, when the acid-forming function of the stomach is reduced, it is advisable to prescribe P. in combination with diluted hydrochloric acid.
P. appoint inside: adults 0.2-0.5 g per dose 2-3 times a day before meals or with meals in powders or in 1-3% solution of hydrochloric acid (10-15 drops in half a glass of water) ; children are prescribed 0.05-0.3 g in 0.5-1% solution of hydrochloric acid for admission. Contraindications to taking P. are hyperacid gastritis, exacerbation of stomach ulcers. The drug used in therapeutic doses does not have side effects.
Release form: powder. Storage: in well-closed jars in a cool (from 2 to 15 °), protected from light place.
In addition to the drug pepsin (Pepsinum), the pharmaceutical industry produces the drug acidin-pepsin (Acidin-pepsinum), containing 1 part of pepsin and 4 parts of betaine hydrochloride (see Betaine), which is hydrolyzed in the stomach with the formation of free hydrochloric acid (0 4 g of betaine correspond to approximately 16 drops of dilute hydrochloric acid). Tablets of acidin-pepsin (0.5 and 0.25 g each) are dissolved in half a glass of water and taken 3-4 times a day with meals.
Abroad, tablets containing P. are produced under the names "Acidol-pepsin", "Betacid", "Aci-pepsol", "Pepsamin".
Bibliography: Andreeva N. S. et al. X-ray diffraction analysis of pepsin, Molek. biol., t. 12, no. 4, p. 922, 1978, bibliogr.; Lobareva L. S. and Stepanov V. M. Carboxyl proteinases of mold fungi, in the book: Usp. biol, chem., ed. B. N. Stepanenko, vol. 19, p. 83, M., 1978, bibliography; Mosolov VV Proteolytic enzymes, p. 101 and others, M., 1971; Northrop D., Kunitz M. and Herriott R. Crystalline enzymes, trans. from English, p. 32, M., 1950; Radbil O. S. Pharmacological bases for the treatment of diseases of the digestive system, p. 78, Moscow, 1976; Acid proteases, structure, function and biology, ed. by J. Tang, N. Y., 1977; Tang J. Evolution in the structure and function of carboxyl proteases, Molec, cell. Biochem., v. 26, p. 93, 1979.
L. A. Lokshina; H. V. Korobov (farm.).
Digestion occurs under the action of proteases - peptide hydrolases. Proteases that hydrolyze peptide bonds within the molecule are endopeptidases, terminal amino acids are exopeptidases.
Specificity of action of proteases. Trypsin preferentially hydrolyzes peptide bonds formed by carboxyl groups of arginine and lysine. Chymotrypsins are most active against peptide bonds formed by carboxyl groups of aromatic amino acids. Carboxypeptidases A and B are zinc-containing enzymes that cleave off C-terminal amino acid residues. Moreover, carboxypeptidase A mainly cleaves off amino acids containing aromatic or hydrophobic radicals, and carboxypeptidase B - arginine and lysine residues. The last stage of digestion - the hydrolysis of small peptides, occurs under the action of the enzymes aminopeptidases and dipeptidases, which are synthesized by the cells of the small intestine in an active form.
Dipeptidases break down dipeptides into amino acids, but do not act on tripeptides.
As a result of the sequential action of all digestive proteases, most food proteins are broken down into free amino acids.
Endopeptidases (endoproteinases) are proteolytic enzymes (pepsin, trypsin, chymotrypsin) that cleave peptide bonds within the peptide chain. With the greatest speed, they hydrolyze the bonds formed by certain amino acids.
Exopeptidases (exoproteinases) are enzymes that hydrolyze proteins by cleaving amino acids from the end of the peptide: carboxypeptidases from the C-terminus, aminopeptidases from the N-terminus, dipeptidases cleave dipeptides. Exopeptidases are synthesized in the cells of the small intestine (aminopeptidases, dipeptidases) and in the pancreas (carboxypeptidase). These enzymes function intracellularly in the intestinal epithelium and, in a small amount, in the intestinal lumen.
Exopeptidases cleave off terminal amino acids, freeing them from the burden of the peptide bond, VIVA LA RESISTANCE!!!
Pepsinogen is a protein consisting of a single polypeptide chain with a molecular weight of 40 kD. Under the action of HCl, it turns into active pepsin (with an optimum pH of 1.0-2.5. During activation, as a result of partial proteolysis, 42 amino acid residues are cleaved from the N-terminus of the pepsinogen molecule, which contain almost all positively charged amino acids present in pepsinogen. Thus, in active pepsin, negatively charged amino acids, which are involved in the conformational rearrangements of the molecule and the formation of the active center, are predominant.
Activation of pancreatic enzymes. Proenzymes of a number of proteases are synthesized in the pancreas: trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidases A and B. In the intestine, they are converted by partial proteolysis into the active enzymes trypsin, chymotrypsin, elastase, and carboxypeptidases A and B.
Trypsinogen is activated by the intestinal epithelial enzyme enteropeptidase. This enzyme cleaves off the Val-(Asp)4-Lys hexapeptide from the N-terminus of the trypsinogen molecule. A change in the conformation of the remaining part of the polypeptide chain leads to the formation of an active center, and active trypsin is formed. The Val-(Asp)4-Lys sequence is inherent in most of the known trypsinogens in various organisms, from fish to humans.
(?) 76. Diagnostic value of biochemical analysis of gastric and duodenal juice. Give a brief description of the composition of these juices.
Gastric juice is a complex digestive juice produced by various cells of the gastric mucosa. Gastric juice contains hydrochloric acid and a number of mineral salts, as well as various enzymes, the most important of which are pepsin, which breaks down proteins, chymosin (rennet), which curdles milk, and lipase, which breaks down fats. An integral part of the gastric juice is also mucus, which plays an important role in protecting the gastric mucosa from irritating substances that have entered it; with high acidity of gastric juice, mucus neutralizes it. In addition to hydrochloric acid, enzymes, salts and mucus, gastric juice also contains a special substance - the so-called. internal factor of Castle. This substance is necessary for the absorption of vitamin B12 in the small intestine, which ensures the normal maturation of red blood cells in the bone marrow. In the absence of the Castle factor in the gastric juice, which is usually associated with a disease of the stomach, and sometimes with its surgical removal, a severe form of anemia develops. Analysis of gastric juice is a very important method for the study of patients with diseases of the stomach, intestines, liver, gallbladder, blood, etc.
Duodenal juice - digestive juice of the duodenum, consisting of pancreatic secretion, bile, juice of intestinal crypts and duodenal glands.
(?) 77. Pancreatic proteinases and pancreatitis. The use of proteinase inhibitors for the treatment of pancreatitis.
pancreatitis is an inflammation of the pancreas. The disease can occur in acute (quickly and violently) or chronic (long and sluggish) form, with periods of exacerbation of chronic pancreatitis.
Causes of pancreatitis
Alcohol consumption and gallbladder disease (primarily gallstone disease) are the causes of pancreatitis in 95-98% of cases.
Other risk factors that can trigger inflammation of the pancreas:
Normally, inactive enzyme precursors are produced in the pancreas - their transition to the active form occurs directly in the duodenum, where they enter through the pancreatic duct and the common bile duct.
Under the influence of various factors (for example, a stone blocking the bile duct), the pressure in the pancreatic duct increases, the outflow of its secret is disturbed, and premature activation of enzymes occurs. As a result, instead of digesting food, the enzymes begin to digest the pancreas itself. Acute inflammation develops.
In chronic pancreatitis, the normal tissue of the pancreas is gradually replaced by scar tissue, and exocrine (production of enzymes) and endocrine (production of hormones, including insulin) functions of the gland develop.
In 1930, Frey discovered the first kallikrein inhibitor. Subsequently, this substance was obtained in its pure form and used for therapeutic purposes. In clinical practice, for the treatment of acute pancreatitis, protease inhibitors trasilol, contrical, tzalol, pantrypin, etc. are widely used. Trasilol is a polypeptide with a molecular weight of 11,600, consisting of 18 amino acids. It inhibits kallikrein, trypsin, chymotrypsin and plasmin by forming an inactive complex with enzymes. In addition, trasylol and other protease inhibitors have a pronounced vasopressor effect and thus are important in the prevention of shock. Under the influence of trasylol, according to various authors, the pain syndrome is quickly stopped, toxemia and symptoms of shock are reduced. When prescribing large doses of one of the protease inhibitors, we also in most cases observed an improvement in the condition of seriously ill patients (disappearance of pain, etc.). However, the treatment has always been complex and it is difficult to say how much protease inhibitors helped in these cases.
Hydrolyzing peptides and proteins, endopeptidase, as well as medicine.
Trypsin is a digestive enzyme.
Trypsin is the most important enzyme for intestinal digestion, which breaks down proteins entering the duodenum of food.Trypsin is synthesized in the pancreas in the form of trypsinogen proenzyme and, in this form, as part of pancreatic juice, enters the duodenum, where, in an alkaline environment, under the influence of the proteolytic enzyme enterokinase, the hexapeptide is removed from the trypsinogen molecule and the biologically active structure of trypsin is formed.
After activation of trypsin by enterokinase, the process of autocatalysis begins and trypsin then acts as an enzyme that activates trypsinogen, chymotrypsinogen, procarboxypeptidase, prophospholipase, and other pancreatic proenzymes.
In the blood of healthy patients, the average content of trypsin is 169 ± 17.6 ng/ml. The limits of fluctuations (in children) are from 98.2 to 229.6 ng / ml.
Trypsin is a drug
Trypsin is the international non-proprietary name (INN) of the drug, as well as the trade name of the drug. Trypsin for ATC is included in the following groups and has codes:- "B06 Other hematological preparations", code "B06AA07 Trypsin"
- "D03 Preparations for the treatment of wounds and ulcers", code "D03BA01 Trypsin"
- "M09 Other drugs for the treatment of diseases of the musculoskeletal system", "M09AB52 Trypsin in combination with other drugs."
Indications for the use of crystalline trypsin
Trypsin is a component of combined drugs
Trypsin is also used as part of combined enzyme, immunomodulatory and other drugs. In particular, trypsin is included in Wobenzym, Phlogenzym, Chymopsin.
Trypsin has contraindications, side effects and application features, consultation with a specialist is necessary.
As an inactive precursor (proenzyme) trypsinogen. Trypsins from a number of animals were obtained in crystalline form (for the first time in 1932). The bovine trypsin molecule (molecular weight about 24 kDa) consists of 223 amino acid residues forming one polypeptide chain and contains 6 disulfide bonds. The isoelectric point of trypsin is at 10.8, and the optimum catalytic activity is at pH 7.8-8.0.
Trypsins belong to the group of serine proteases and contain serine and histidine residues in the active center. Trypsins are easily subjected to self-digestion (autolysis), which leads to contamination of trypsin preparations with inactive products (an industrial preparation contains up to 50% of inactive impurities). Trypsin preparations of high purity are obtained by chromatographic methods.
Physical Properties
Trypsin is a colorless crystalline substance with a melting point of about 150.
Biological properties and functions
The main function is digestion. Catalyzes the hydrolysis of proteins and peptides. It may be in an inactive state in the form of trypsinogen. It is activated, including by the intestinal enzyme enteropeptidase, by cleavage of the hexapeptide. It also catalyzes the hydrolysis of ester waxes. Optimum catalytic activity - at 7.8-8. The active center is of a protein nature and consists mainly of serine and histidine. Synthesized as trypsinogen in the pancreas and used in the intestines of mammals and fish. Transforms other hydrolase proenzymes into active enzymes.
Application
Trypsin is used to make medicines. Trypsin preparations have anti-inflammatory and anti-edematous effects (when administered intravenously and intramuscularly); capable of selectively splitting tissues that have undergone necrosis. In medicine, trypsin is used to treat wounds, burns, thrombosis, often in combination with other enzymes and with antibiotics. Trypsin is a part of preparations for systemic enzyme therapy - Wobenzym, Phlogenzym.
Literature
- Northrop D., Kunitz M., Herriott R. Crystalline enzymes, trans. from English, M., 1950;
- Mosolov V.V.. Proteolytic enzymes, M., 1971.
- V. I. Struchkov, A. V. Grigoryan, V. K. Gostishchev, S. V. Lokhvitsky, L. S. Tapinsky Proteolytic enzymes in purulent surgery., M., 1970;
- Problems of Medical Enzymology” (edited by S. R. Mardashov). M., 1970;
- K. N. Veremeenko Proteolytic enzymes of the pancreas and their use in the clinic. Kyiv, 1967
- Systemic enzyme therapy. Experience and prospects / Ed. IN AND. Kulakova, V.A. Nasonova, V.S. Saveliev.- St. Petersburg: Inter-Medica. 2004. - 264 p.
- Tets V.V., Knorring G.Yu., Artemenko N.K. and etc. Influence of exogenous proteolytic enzymes on bacteria // Antibiotics and Chemotherapy. - 2004. - T. 49. - No. 12. - P. 9–13.
- Polyenzyme preparations in purulent surgery: Guidelines / Ed. corresponding member RAMS N.A. Efimenko. - M., 2005. - 32 p.
Related enzymes
The "closest relatives" of trypsin are trypsinogen, pepsin, chymotrypsin. Anionic analogues of trypsin have been found in higher animals, while neutral analogues have been found in many animals and plants.
Change in hydrolytic properties
Trypsin activity is suppressed by organophosphorus compounds, some metals, and a number of high-molecular protein substances - trypsin inhibitors, contained in the tissues of animals, plants and microorganisms. Ions 2+ , 2+ , 2+ , 2+ , 2+ increase the hydrolytic activity of trypsin.
Links
| Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21) | |
|---|---|
| Digestive enzymes | Enteropeptidase - trypsin- Chymotrypsin - Elastase (Neutrophilic, Pancreatic) |
| Coagulation | factors: Thrombin - Factor VIIa - Factor IXa - Factor Xa - Factor XIa - Factor XIIa - Kallikrein (PSA) fibrinolysis: Plasmin - Plasminogen Activator (Tissue - Urokinase) |
| Complement system | Factor B - Factor D - Factor I - MASP (MASP1, MASP2) - C3 convertase |
| Others, immune system: | Himase - Granzyme - Tryptase - Proteinase 3/Myeloblastin |
| From biotoxins: | Ancrod - Batroxobin |
| Rest | Acrosin - Prolyl endopeptidase - Pronase - Proprotein convertase (1, 2) - Reelin - Subtilisin/Furin - Streptokinase - S1P - Cathepsin ( , ) |
Wikimedia Foundation. 2010 .
Synonyms:See what "Trypsin" is in other dictionaries:
- (Trypsinum). An endogenous proteolytic enzyme that breaks peptide bonds in a protein molecule. It also cleaves high molecular weight protein breakdown products, peptone-type polypeptides, as well as some low molecular weight peptides containing ... ... Medicine Dictionary
TRIPSIN- TRIPSIN, an enzyme that is part of the pancreatic juice, described by Kiihne in 1867, belongs to the group of proteases. It breaks down proteins, protamines, peptones and polypeptides. In the purest form, free from lipase and amylase, obtained by the method ... ... Big Medical Encyclopedia
TRIPSIN- Trypsinum. Properties. Obtained from the pancreas of cattle. It is a white or white with a yellowish tint powder or odorless porous mass. Easily soluble in water and isotonic sodium chloride solution; pH 0.2% aqueous plant ... Domestic veterinary drugs
A pancreatic enzyme that dissolves protein. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. trypsin (gr. thrypsis liquefaction) a digestive enzyme synthesized in the pancreas in the form of an inactive ... ... Dictionary of foreign words of the Russian language
TRIPSIN, a digestive enzyme secreted by the pancreas. It is excreted in an inactive form (so as not to damage the tissues on the way to the intestines), then the small intestine enzyme converts it into active trypsin. Cleaves peptide bonds of amino acids... Scientific and technical encyclopedic dictionary
Digestive enzyme produced as an inactive trypsinogen by the pancreas of humans and animals; breaks down proteins in the intestines... Big Encyclopedic Dictionary
TRIPSIN, trypsin, pl. no, husband. (from Greek tripsis grinding) (biol.). A substance in pancreatic juice that converts proteins into simpler, soluble compounds. Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov
Proteolytic an enzyme synthesized by pancreatic cells in the form of an inactive trypsinogen precursor. It activates pancreatic proenzymes and occupies a key position in digestion in the small intestine. In crystalline ... ... Biological encyclopedic dictionary
Exist., number of synonyms: 4 drug (1413) protease (4) enzyme (253) ... Synonym dictionary
trypsin- One of the main digestive (proteolytic) enzymes, catalyzing the hydrolysis of peptides and other compounds at the site of bonds, in which the carboxyl groups of arginine and lysine participate)
Loading...