What are called enzymes in chemistry.  Biological enzymes

Any living organism is a perfect system in which, literally every minute, some kind of And these processes are not complete without the participation of enzymes. So what are enzymes? What is their role in the life of the organism? What are they made of? What is the mechanism of their influence? Below are the answers to all these questions.

What are enzymes?

Enzymes, or, as they are also called, enzymes, are protein complexes. These are the catalysts for chemical reactions. In fact, the role of enzymes is difficult to overestimate, because not a single process in a living cell and the whole organism can do without them.

The term "enzyme" itself was proposed in the 17th century by Helmont. And although the great scientists of that time understood that meat is digested when present, and starch breaks down into simple sugars under the influence of saliva, no one knew exactly what caused such processes. But already at the beginning of the 19th century, Kirchhoff for the first time isolated the saliva enzyme - amylase. A few years later, gastric pepsin was described. Since then, the science of enzymology began to develop actively.

What are enzymes? Properties and mechanism of action

To begin with, it is worth noting that all enzymes are either pure proteins or protein complexes. To date, the amino acid sequence of most enzymes in the human body has been deciphered.

The main property of enzymes is high specificity. Each enzyme can only catalyze one type of reaction. For example, proteolytic enzymes can only cleave bonds between amino acid residues of a protein molecule. Sometimes one substrate (object of enzyme action) can be affected by several enzymes similar in structure at once.

But an enzyme can be specific not only with respect to the reaction, but also with respect to the substrate. The most common is group. This means that a certain enzyme can only affect a certain group of substrates that have a similar structure.

But sometimes there is the so-called absolute specificity. This means that the enzyme can bind to the active site of only one substrate. Of course, such specificity is rare in nature. But for example, we can recall the enzyme urease, which can only catalyze the hydrolysis of urea.

Now we have found out what enzymes are. But these substances can be completely different. Therefore, they are classified.

Enzyme classification

Modern science knows more than two thousand enzymes, but this is by no means an exact number. For convenience, they are divided into six main groups depending on the catalyzed reaction.

• Oxidoreductases are a group of enzymes that are involved in redox reactions. As a rule, they act either as donors or acceptors of electrons and hydrogen ions. These enzymes are very important, as they are involved in the processes of cellular and mitochondrial respiration.
• Transferases are enzymes that transfer atomic groups from one substrate to another. Participate in intermediate metabolism.
• Lyases - such enzymes are able to cleave atomic groups from the substrate without a hydrolytic reaction. As a rule, as a result of such a process, a molecule of water or carbon dioxide is formed.
• Hydrolases are enzymes that catalyze the hydrolytic cleavage of a substrate using
• Isomerases - as the name suggests, these enzymes catalyze the transition of a substance from one isomeric form to another.
• Ligases are enzymes that catalyze synthetic reactions.

As you can see, enzymes are very important substances for the body, without which vital processes are simply impossible.

Enzymes (enzymes): health significance, classification, application. Plant (food) enzymes: sources, benefits.

Enzymes (enzymes) are macromolecular substances of a protein nature that perform the functions of catalysts in the body (activate and accelerate various biochemical reactions). Fermentum in Latin means fermentation. The word enzyme has Greek roots: "en" - inside, "zyme" - leaven. These two terms, enzymes and enzymes, are used interchangeably, and the science of enzymes is called enzymology.

Importance of enzymes for health. Application of enzymes

Enzymes are called the keys of life for a reason. They have a unique property to act specifically, selectively, only on a narrow range of substances. Enzymes cannot replace each other.

To date, more than 3 thousand enzymes are known. Each cell of a living organism contains hundreds of different enzymes. Without them, not only the digestion of food and its transformation into those substances that cells are able to assimilate is impossible. Enzymes are involved in the processes of renewal of the skin, blood, bones, regulation of metabolism, body cleansing, wound healing, visual and auditory perception, the functioning of the central nervous system, and the implementation of genetic information. Respiration, muscle contraction, heart function, cell growth and division - all these processes are supported by the uninterrupted operation of enzyme systems.

Enzymes play an extremely important role in supporting our immunity. Specialized enzymes are involved in the production of antibodies necessary to fight viruses and bacteria, activate the work of macrophages - large predatory cells that recognize and neutralize any foreign particles that enter the body. Removal of waste products of cells, neutralization of poisons, protection against infection - all these are the functions of enzymes.

Special enzymes (bacteria, yeast, rennet) play an important role in the production of fermented vegetables, fermented milk products, dough fermentation, and cheese making.

Enzyme classification

According to the principle of action, all enzymes (according to the international hierarchical classification) are divided into 6 classes:

1. Oxidoreductases - catalase, alcohol dehydrogenase, lactate dehydrogenase, polyphenol oxidase, etc.;
2. Transferases (transfer enzymes) - aminotransferases, acyltransferases, phosphorotransferases, etc.;
3. Hydrolases - amylase, pepsin, trypsin, pectinase, lactase, maltase, lipoprotein lipase, etc.;
4. Liase;
5. Isomerases;
6. Ligases (synthetases) - DNA polymerase, etc.

Each class is made up of subclasses, and each subclass is made up of groups.

All enzymes can be divided into 3 large groups:

1. Digestive - act in the gastrointestinal tract, are responsible for the processing of nutrients and their absorption into the systemic circulation. Enzymes that are secreted by the walls of the small intestine and the pancreas are called pancreatic;
2. Food (vegetable) - come (should come) with food. Foods in which food enzymes are present are sometimes referred to as live foods;
3. Metabolic - start metabolic processes inside cells. Each system of the human body has its own network of enzymes.

Digestive enzymes, in turn, are divided into 3 categories:

1. Amylases - salivary amylase, pancreatic lactase, salivary maltase. These enzymes are present in both saliva and the intestines. They act on carbohydrates: the latter break down into simple sugars and easily penetrate into the blood;
2. Proteases are produced by the pancreas and stomach lining. They help to digest proteins, and also normalize the microflora of the digestive tract. Present in the intestines and gastric juice. Proteases include pepsin and chymosin of the stomach, erepsin of kilechny juice, pancreatic carboxypeptidase, chymotrypsin, trypsin;
3. Lipase is produced by the pancreas. Present in gastric juice. Helps break down and absorb fats.

The action of enzymes

The optimal temperature for the vital activity of enzymes is about 37 degrees, that is, body temperature. Enzymes have tremendous power: they make seeds germinate, fats “burn”. On the other hand, they are extremely sensitive: at temperatures above 42 degrees, enzymes begin to break down. Both cooking and deep freezing kill enzymes and lose their vitality. In canned, sterilized, pasteurized and even frozen foods, enzymes are partially or completely destroyed. But not only dead food, but also too cold and hot dishes kill enzymes. When we eat food that is too hot, we kill digestive enzymes and burn the esophagus. The stomach greatly increases in size, and then, due to spasms of the muscle that holds it, it becomes like a cock's comb. As a result, food enters the duodenum in an unprocessed state. If this happens constantly, problems such as dysbacteriosis, constipation, intestinal upset, stomach ulcers may appear. From cold dishes (ice cream, for example), the stomach also suffers - first it shrinks, and then increases in size, and the enzymes are frozen. Ice cream begins to ferment, gases are released and the person gets bloating.

Digestive enzymes

It's no secret that good digestion is an essential condition for a full life and active longevity. Digestive enzymes play a critical role in this process. They are responsible for digestion, adsorption and assimilation of food, building our body like construction workers. We can have all building materials - minerals, proteins, fats, water, vitamins, but without enzymes, as without workers, construction will not move a single step.

A modern person consumes too much food, for the digestion of which there are practically no enzymes in the body, for example, starchy foods - pasta, bakery products, potatoes.

If you eat a fresh apple, it will be digested by its own enzymes, and the action of the latter is visible to the naked eye: the darkening of a bitten apple is the work of enzymes that are trying to heal the “wound”, protect the body from the threat of mold and bacteria. But if you bake an apple in order to digest it, the body will have to use its own enzymes for digestion, since cooked food lacks natural enzymes. In addition, those enzymes that “dead” foods take from our body, we lose forever, since their reserves in our body are not unlimited.

Plant (food) enzymes

Eating foods rich in enzymes not only facilitates digestion, but also releases energy that the body can use to cleanse the liver, patch holes in the immune system, rejuvenate cells, protect against tumors, etc. At the same time, a person feels lightness in the stomach, feels cheerful, and looks good. And raw plant fiber, which enters the body with living food, is required to feed the microorganisms that produce metabolic enzymes.

Plant enzymes give us life and energy. If you plant two nuts in the ground - one fried and the other raw, soaked in water, then the fried one will simply rot in the ground, and vitality will wake up in the raw grain in the spring, because it contains enzymes. And it is quite possible that a large lush tree will grow out of it. So a person, consuming food that contains enzymes, along with it receives life. Foods devoid of enzymes cause our cells to work without rest, overwork, age and die. If there are not enough enzymes, “waste products” begin to accumulate in the body: poisons, toxins, dead cells. This leads to weight gain, disease and early aging. An interesting and at the same time sad fact: in the blood of the elderly, the content of enzymes is about 100 times lower than in the young.

enzymes in foods. Plant Enzyme Sources

Sources of food enzymes are vegetable products from the garden, garden, ocean. These are mainly vegetables, fruits, berries, herbs, cereals. Own enzymes contain bananas, mangoes, papaya, pineapples, avocados, aspergillus plant, germinated grains. Plant enzymes are present only in raw, living foods.

Wheat sprouts are a source of amylase (breaking down carbohydrates), papaya fruits contain proteases, and papaya and pineapple fruits contain peptidases. Sources of lipase (breaking down fats) are fruits, seeds, rhizomes, tubers of cereal crops, mustard and sunflower seeds, legume seeds. Papain (protein-splitting) is rich in bananas, pineapples, kiwi, papaya, mangoes. The source of lactase (an enzyme that breaks down milk sugar) is barley malt.

Benefits of plant (food) enzymes over animal (pancreatic) enzymes

Plant enzymes begin to process food already in the stomach, and pancreatic enzymes cannot work in an acidic gastric environment. Once food enters the small intestine, the plant enzymes will pre-digest it, reducing strain on the intestines and allowing nutrients to be better absorbed. In addition, plant enzymes continue their work in the intestines.

How to eat so that the body has enough enzymes?

Everything is very simple. Breakfast should consist of fresh berries and fruits (plus protein dishes - cottage cheese, nuts, sour cream). Every meal should start with vegetable salads with herbs. It is desirable that one meal a day includes only raw fruits, berries and vegetables. Dinner should be light - consist of vegetables (with a piece of chicken breast, boiled fish or a portion of seafood). Several times a month it is useful to arrange fasting days on fruits or freshly squeezed juices.

For high-quality assimilation of food and good health, enzymes are simply irreplaceable. Overweight, allergies, various diseases of the gastrointestinal tract - all these and many other problems can be overcome with a healthy diet. And the role of enzymes in nutrition is enormous. Our task is simply to make sure that every day and in sufficient quantities they are present in our dishes. Good health to you!

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History of Enzyme Science

All life processes are based on thousands of chemical reactions. They go in the body without the use of high temperature and pressure, that is, in mild conditions. Substances that are oxidized in human and animal cells burn quickly and efficiently, enriching the body with energy and building material. But the same substances can be stored for years both in canned (isolated from air) form and in air in the presence of oxygen. For example, canned meat and fish, pasteurized milk, sugar, cereals do not decompose during rather long storage. The ability to quickly digest foods in a living organism is due to the presence in the cells of special biological catalysts - enzymes.

Enzymes are specific proteins that are part of all cells and tissues of living organisms, playing the role of biological catalysts. People have known about enzymes for a long time. At the beginning of the last century in St. Petersburg, K.S. Kirchhoff found out that germinated barley is able to convert starch polysaccharide into maltose disaccharide, and yeast extract breaks down beet sugar into monosaccharides - glucose and fructose. These were the first studies in fermentology. And the practical application of enzymatic processes has been known since time immemorial. This is the fermentation of grapes, and sourdough in the preparation of bread, and cheese making, and much more.

Now in different textbooks, manuals and in the scientific literature, two concepts are used: “enzymes” and “enzymes”. These names are identical. They mean the same thing - biological catalysts. The first word is translated as "sourdough", the second - "in yeast".

For a long time, they did not imagine what happens in yeast, what kind of force present in them causes substances to break down and turn into simpler ones. It wasn't until the invention of the microscope that it was discovered that yeast is an accumulation of a large number of microorganisms that use sugar as their main nutrient. In other words, each yeast cell is "stuffed" with enzymes that can break down sugar. But at the same time, other biological catalysts were also known, not enclosed in a living cell, but freely “living” outside it. For example, they were found in the composition of gastric juices, cell extracts. In this connection, two types of catalysts were distinguished in the past: it was believed that the enzymes themselves were inseparable from the cell and could not function outside it, that is, they were "organized." And the "disorganized" catalysts that can work outside the cell were called enzymes. This opposition of "living" enzymes and "non-living" enzymes was explained by the influence of the vitalists, the struggle between materialism and idealism in natural science. The views of scholars are divided. The founder of microbiology, L. Pasteur, argued that the activity of enzymes is determined by the life of the cell. If the cell is destroyed, then the action of the enzyme will also stop. Chemists led by J. Liebig developed a purely chemical theory of fermentation, proving that the activity of enzymes does not depend on the existence of a cell.

In 1871, Russian physician M. M. Manasseina destroyed yeast cells by rubbing them with river sand. The cell sap, separated from the remnants of the cells, retained its ability to ferment sugar. This simple and convincing experience of a Russian doctor was left without due attention in Tsarist Russia. A quarter of a century later, the German scientist E. Buchner obtained cell-free juice by pressing live yeast under pressure up to 5·10 6 Pa. This juice, like live yeast, fermented sugar to form alcohol and carbon monoxide (IV):

The works of A. N. Lebedev on the study of yeast cells and the works of other scientists put an end to vitalistic ideas in the theory of biological catalysis, and the terms "enzyme" and "enzyme" began to be used as equivalent.

Nowadays fermentology is an independent science. About 2000 enzymes have been isolated and studied. A contribution to this science was made by Soviet scientists - our contemporaries A. E. Braunshtein, V. N. Orekhovich, V. A. Engelgard, A. A. Pokrovsky and others.

Chemical nature of enzymes

At the end of the last century, it was suggested that enzymes are proteins or some substances very similar to proteins. The loss of enzyme activity upon heating is very similar to thermal protein denaturation. The temperature range during denaturation and inactivation is the same. As is known, protein denaturation can be caused not only by heating, but also by the action of acids, salts of heavy metals, alkalis, and prolonged exposure to ultraviolet rays. These same chemical and physical factors lead to the loss of enzyme activity.

In solutions, enzymes, like proteins, behave in a similar way under the influence of an electric current: the molecules move towards the cathode or anode. A change in the concentration of hydrogen ions in solutions of proteins or enzymes leads to the accumulation of a positive or negative charge by them. This proves the amphoteric nature of enzymes and also confirms their protein nature. Another evidence of the protein nature of enzymes is that they do not pass through semipermeable membranes. This also proves their large molecular weight. But if enzymes are proteins, then their activity should not decrease during dehydration. Experiments confirm the correctness of this assumption.

An interesting experiment was carried out in the laboratory of IP Pavlov. When receiving gastric juice through a fistula in dogs, the staff found that the more protein in the juice, the greater its activity, i.e. the protein being detected is the enzyme of gastric juice.

Thus, the phenomena of denaturation and mobility in an electric field, the amphoteric nature of molecules, their high molecular nature, and the ability to precipitate from solution under the action of water-removing agents (acetone or alcohol) prove the protein nature of enzymes.

To date, this fact has been established by many, even more subtle physical, chemical or biological methods.

We already know that proteins are very different in composition and, above all, they can be simple or complex. What kind of proteins are currently known enzymes?

Scientists from various countries have found that many enzymes are simple proteins. This means that during hydrolysis, the molecules of these enzymes decompose only to amino acids. Nothing but amino acids can be found in the hydrolyzate of such enzyme proteins. Simple enzymes include pepsin - an enzyme that digests proteins in the stomach and is contained in gastric juice, trypsin - an enzyme in pancreatic juice, papain - a plant enzyme, urease, etc.

Complex enzymes include, in addition to amino acids, substances that have a non-protein nature. For example, redox enzymes built into mitochondria contain, in addition to the protein part, iron, copper, and other thermostable groups. The non-protein part of the enzyme can also be more complex substances: vitamins, nucleotides (nucleic acid monomers), nucleotides with three phosphorus residues, etc. We agreed to call the non-protein part in such complex proteins a coenzyme, and the protein part apoenzyme.

The difference between enzymes and non-biological catalysts

In school textbooks and manuals on chemistry, the action of catalysts is analyzed in detail, an idea is given of the energy barrier, activation energy. We only recall that the role of catalysts lies in their ability to activate the molecules of the substances entering into the reaction. This leads to a decrease in the activation energy. The reaction proceeds not in one, but in several stages with the formation of intermediate compounds. Catalysts do not change the direction of the reaction, but only affect the rate at which the state of chemical equilibrium is reached. A catalyzed reaction always uses less energy than a non-catalyzed one. During the reaction, the enzyme changes its packaging, “tenses up” and, at the end of the reaction, takes on its original structure and returns to its original form.

Enzymes are the same catalysts. They are characterized by all the laws of catalysis. But enzymes are proteins, and this gives them special properties. What do enzymes have in common with the catalysts familiar to us, for example, platinum, vanadium (V) oxide, and other inorganic reaction accelerators, and what distinguishes them?

The same inorganic catalyst can be used in different industries. And the enzyme catalyzes only one reaction or one type of reaction, i.e., it is more specific than an inorganic catalyst.

Temperature always affects the rates of chemical reactions. Most reactions with inorganic catalysts take place at very high temperatures. As the temperature rises, the reaction rate, as a rule, increases (Fig. 1). For enzymatic reactions, this increase is limited to a certain temperature (temperature optimum). A further increase in temperature causes changes in the enzyme molecule, leading to a decrease in the reaction rate (Fig. 1). But some enzymes, such as those of microorganisms found in the water of hot natural springs, not only withstand temperatures close to the boiling point of water, but even show their maximum activity. For the majority of enzymes, the temperature optimum is close to 35-45 °C. At higher temperatures, their activity decreases, and then complete thermal denaturation occurs.

Rice. 1. The effect of temperature on the activity of enzymes: 1 - an increase in the reaction rate, 2 - a decrease in the reaction rate.

Many inorganic catalysts show their maximum efficiency in a strongly acidic or strongly alkaline environment. In contrast, enzymes are active only at physiological values ​​of the acidity of the solution, only at such a concentration of hydrogen ions that is compatible with the life and normal functioning of a cell, organ or system.

Reactions involving inorganic catalysts proceed, as a rule, at high pressures, while enzymes operate at normal (atmospheric) pressure.

And the most surprising difference between an enzyme and other catalysts is that the rate of reactions catalyzed by enzymes is tens of thousands, and sometimes millions of times higher than that which can be achieved with the participation of inorganic catalysts.

Hydrogen peroxide, known to all, used in everyday life as a bleaching and disinfectant, decomposes slowly without catalysts:

In the presence of an inorganic catalyst (iron salts), this reaction proceeds somewhat faster. And catalase (an enzyme present in almost all cells) destroys hydrogen peroxide at an unimaginable rate: one catalase molecule breaks down more than 5 million H 2 O 2 molecules in one minute.

The universal distribution of catalase in the cells of all organs of aerobic organisms and the high activity of this enzyme are explained by the fact that hydrogen peroxide is a powerful cellular poison. It is produced in cells as a by-product of many reactions, but the enzyme catalase is on guard, which immediately breaks down hydrogen peroxide into harmless oxygen and water.

Active site of the enzyme

An obligatory stage in the catalyzed reaction is the interaction of the enzyme with the substance whose transformation it catalyzes - with the substrate: an enzyme-substrate complex is formed. In the example above, hydrogen peroxide is the substrate for the action of catalase.

It is interesting that in enzymatic reactions the substrate molecule is many times smaller than the protein-enzyme molecule. Consequently, the substrate cannot come into contact with the entire huge molecule of the enzyme, but only with some of its small area or even with a separate group, an atom. To confirm this assumption, the scientists cleaved off one or more amino acids from the enzyme, and this had little or no effect on the rate of the catalyzed reaction. But the cleavage of certain specific amino acids or groups led to a complete loss of the catalytic properties of the enzyme. Thus, the concept of the active center of the enzyme was formed.

The active center is such a region of the protein molecule that provides the connection of the enzyme with the substrate and makes it possible for further transformations of the substrate. Some active centers of different enzymes have been studied. This is either a functional group (for example, the OH group of serine), or a single amino acid. Sometimes several amino acids in a certain order are needed to provide catalytic action.

As part of the active center, sections differing in their functions are distinguished. Some sections of the active center provide adhesion to the substrate, strong contact with it. Therefore, they are called anchor or contact areas. Others perform their own catalytic function, activate the substrate - catalytic sites. Such a conditional separation of the active center helps to more accurately represent the mechanism of the catalytic reaction.

The type of chemical bond in enzyme-substrate complexes has also been studied. The substance (substrate) is retained on the enzyme with the participation of various types of bonds: hydrogen bridges, ionic, covalent, donor-acceptor bonds, van der Waals cohesion forces.

Deformation of enzyme molecules in solution leads to the appearance of its isomers that differ in tertiary structure. In other words, the enzyme orients its functional groups included in the active center in such a way that the greatest catalytic activity is manifested. But the substrate molecules can also be deformed, "strain" when interacting with the enzyme. These modern ideas about the enzyme-substrate interaction differ from the previously dominant theory of E. Fischer, who believed that the substrate molecule exactly corresponds to the active site of the enzyme and approaches it like a key to a lock.

Enzyme Properties

The most important property of enzymes is the preferential acceleration of one of several theoretically possible reactions. This allows the substrates to choose the chains of transformations that are most beneficial for the organism from a number of possible pathways.

Enzymes can catalyze both forward and reverse reactions depending on the conditions. For example, pyruvic acid, under the influence of the enzyme lactate dehydrogenase, is converted into the end product of fermentation - lactic acid. The same enzyme also catalyzes the reverse reaction, and it got its name not from the direct reaction, but from the reverse reaction. Both reactions occur in the body under different conditions:

This property of enzymes is of great practical importance.

Another important property of enzymes is thermolability, i.e., high sensitivity to temperature changes. We have already said that enzymes are proteins. For most of them, temperatures above 70°C result in denaturation and loss of activity. It is known from the course of chemistry that an increase in temperature by 10 ° C leads to an increase in the reaction rate by 2-3 times, which is also characteristic of enzymatic reactions, but up to a certain limit. At temperatures close to 0 °C, the rate of enzymatic reactions slows down to a minimum. This property is widely used in various sectors of the economy, especially in agriculture and medicine. For example, all currently existing methods of preserving a kidney before transplanting it to a patient include cooling this organ in order to reduce the intensity of biochemical reactions and prolong the life of the kidney before it is transplanted to a person. This technique has preserved the health and saved the lives of tens of thousands of people in the world.

Rice. 2. Effect of pH on enzyme activity.

One of the most important properties of enzyme proteins is their sensitivity to the reaction of the environment, the concentration of hydrogen ions or hydroxide ions. Enzymes are active only in a narrow range of acidity or alkalinity (pH). For example, the activity of pepsin in the stomach cavity is maximum at a pH of about 1-1.5. A decrease in acidity leads to a deep violation of the digestive act, underdigestion of food and severe complications. From a biology course, you know that digestion begins already in the oral cavity, where salivary amylase is present. The optimal pH value for it is 6.8-7.4. Different enzymes of the digestive tract are characterized by large differences in the pH optimum (Fig. 2). A change in the reaction of the environment leads to a change in the charges on the enzyme molecule or even in its active center, causing a decrease or complete loss of activity.

The next important property is the specificity of the enzyme action. Catalase splits only hydrogen peroxide, urease - only urea H 2 N-CO-NH 2, i.e. the enzyme catalyzes the conversion of only one substrate, it only “recognizes” its molecule. This specificity is considered absolute. If an enzyme catalyzes the conversion of several substrates that have the same functional group, then this specificity is called group specificity. For example, phosphatase catalyzes the elimination of a phosphoric acid residue:

A kind of specificity is the sensitivity of the enzyme to only one isomer - stereo-chemical specificity.

Enzymes affect the rate of transformation of various substances. But some substances also affect enzymes, dramatically changing their activity. Substances that increase the activity of enzymes, activate them, are called activators, and those that inhibit them are called inhibitors. Inhibitors can affect the enzyme irreversibly. After their action, the enzyme can never catalyze its reaction, since its structure will be greatly changed. This is how salts of heavy metals, acids, alkalis act on the enzyme. The reversible inhibitor can be removed from the solution and the enzyme regains activity. Such reversible inhibition often proceeds in a competitive manner, i.e., a substrate and an inhibitor similar to it compete for the active site. This inhibition can be removed by increasing the concentration of the substrate and displacing the inhibitor from the active site with the substrate.

An important property of many enzymes is that they are found in tissues and cells in an inactive form (Fig. 3). The inactive form of enzymes is called a proenzyme. Classical examples are inactive forms of pepsin or trypsin. The existence of inactive forms of enzymes is of great biological importance. If pepsin or trypsin were produced immediately in an active form, then this would lead to the fact that, for example, pepsin "digested" the wall of the stomach, that is, the stomach "digested" itself. This does not happen because pepsin or trypsin become active only after entering the stomach cavity or small intestine: several amino acids are cleaved from pepsin under the action of hydrochloric acid contained in gastric juice, and it acquires the ability to break down proteins. And the stomach itself is now protected from the action of digestive enzymes by the mucous membrane lining its cavity.

Rice. 3 Scheme of the conversion of trypsinogen into active trypsin: A - trypsinogen; B - trypsin; 1 - place of peptide detachment; 2 - hydrogen bonds; 3 - disulfide bridge; 4 - peptide cleaved during activation.

The process of enzyme activation proceeds, as a rule, in one of the four ways shown in Figure 4. In the first case, the cleavage of the peptide from the inactive enzyme "opens" the active center and makes the enzyme active.

Rice. 4 Enzyme activation pathways (substrate molecule is shaded):

1 - cleavage from the proenzyme of a small area (peptide) and the transformation of an inactive proenzyme into an active enzyme; 2 - formation of disulfide bonds from SH-groups, releasing the active center; 3 - formation of a protein complex with metals, activating the enzyme; 4 formation of an enzyme complex with some substance (this frees up access to the active center).

The second way is the formation of S-S disulfide bridges, making the active site accessible. In the third case, the presence of a metal activates an enzyme that can only work in combination with this metal. The fourth pathway illustrates activation by some substance that binds to the peripheral region of the protein molecule and deforms the enzyme in such a way as to facilitate access of the substrate to the active site.

In recent years, another way to regulate enzyme activity has been discovered. It turned out that one enzyme, such as lactate dehydrogenase, can be in several molecular forms that differ from each other, although they all catalyze the same reaction. Such different enzyme molecules that catalyze the same reaction are found even inside the same cell. They are called isoenzymes, i.e. enzyme isomers. The already named lactate dehydrogenase has five different isoenzymes. What is the role of several forms of one enzyme? Apparently, the body "insures" some especially important reactions, when, when conditions change in the cell, one or another form of the isoenzyme works, and provides the necessary speed and direction of the process.

And one more important property of enzymes. Often they function in the cell not separately from each other, but are organized in the form of complexes - enzyme systems (Fig. 5): the product of the previous reaction is the substrate for the next one. These systems are built into cell membranes and provide rapid directed oxidation of a substance, "transferring" it from enzyme to enzyme. Synthetic processes in the cell take place in similar enzyme systems.

Enzyme classification

The range of questions studied by fermentology is wide. The number of enzymes used in health care, agriculture, microbiology and other branches of science and practice is large. This created a difficulty in characterizing enzymatic reactions, since one and the same enzyme can be named either by the substrate, or by the type of catalyzed reactions, or by an old term that has become firmly established in the literature: for example, pepsin, trypsin, catalase.

Rice. 5. Proposed structure of a multienzyme complex synthesizing fatty acids (seven enzyme subunits are responsible for seven chemical reactions).

Therefore, in 1961, the International Biochemical Congress in Moscow approved the classification of enzymes, which is based on the type of reaction catalyzed by a given enzyme. The name of the enzyme must contain the name of the substrate, i.e., the compound that this enzyme acts on, and the ending -ase. For example, arginase catalyzes the hydrolysis of arginine.

According to this principle, all enzymes were divided into six classes.

1. Oxidoreductase enzymes that catalyze redox reactions, such as catalase:

2. Transferases - enzymes that catalyze the transfer of atoms or radicals, for example, methyltransferases that transfer a CH3 group:

3. Hydrolases - enzymes that break intramolecular bonds by attaching water molecules, such as phosphatase:

4. Lyases - enzymes that cleave one or another group from the substrate without adding water, in a non-hydrolytic way, for example, cleavage of the carboxyl group by decarboxylase:

5. Isomerases - enzymes that catalyze the transformation of one isomer into another:

Glucose-6-phosphate->glucose-1-phosphate

6. Enzymes that catalyze synthesis reactions, such as the synthesis of peptides from amino acids. This class of enzymes is called synthetases.

Each enzyme was proposed to be encoded with a code of four digits, where the first of them denotes the class number, and the remaining three characterize in more detail the properties of the enzyme, its subclass, and individual catalog number.

As an example of the classification of enzymes, we give a four-digit code assigned to pepsin - 3.4.4L. The number 3 denotes the class of the enzyme - hydrolase. The next number 4 encodes a subclass of peptide hydrolases, i.e., those enzymes that hydrolyze precisely peptide bonds. Another 4 denotes a sub-subclass called peptidyl peptide hydrolases. This subclass already includes individual enzymes, and the first one in it is pepsin, which is assigned the serial number 1.

This is how his code turns out - 3.4.4.1. The points of application of the action of enzymes of the hydrolase class are shown in Figure 6.

Rice. 6. Cleavage of peptide bonds by various proteolytic enzymes.

The action of enzymes

Typically, enzymes are isolated from various objects of animal, plant or microbial origin and their action outside the cell and body is studied. These studies are very important for understanding the mechanism of action of enzymes, studying their composition, and the characteristics of the reactions they catalyze. But the information obtained in this way cannot be mechanically directly transferred to the activity of enzymes in a living cell. Outside the cell, it is difficult to reproduce the conditions under which the enzyme works, for example, in mitochondria or lysosomes. In addition, it is not always known how many of the available enzyme molecules are involved in the reaction - all or only some of them.

It almost always turns out that the cell contains one or another enzyme, the content of which is several tens of times greater than the amount required for normal metabolism. Metabolism is different in intensity at different periods of the cell's life, but there are much more enzymes in it than would be required by the highest level of metabolism. For example, the composition of the cells of the heart muscle contains so much cytochrome c that could carry out oxidation, 20 times more than the maximum oxygen consumption of the heart muscle. Later, substances were discovered that can “turn off” some of the enzyme molecules. These are the so-called inhibitory factors. To understand the mechanism of action of enzymes, it is also important that in the cell they are not just in solution, but are built into the structure of the cell. It is now known which enzymes are built into the outer membrane of the mitochondria, which ones are built into the inner one, and which ones are associated with the nucleus, lysosomes, and other subcellular structures.

The close "territorial" location of the enzyme catalyzing the first reaction to the enzymes catalyzing the second, third and subsequent reactions strongly affects the overall result of their action. For example, a chain of enzymes that transfer electrons to oxygen is built into the mitochondria - the cytochrome system. It catalyzes the oxidation of substrates with the formation of energy, which is stored in ATP.

When extracting enzymes from the cell, the coherence of their joint work is disturbed. Therefore, they try to study the work of enzymes without destroying the structures in which their molecules are built. For example, if a tissue section is held in a substrate solution and then treated with a reagent that gives a colored complex with the reaction products, then the stained areas of the cell will be clearly visible in the microscope: in these areas, an enzyme was localized (located) that cleaved the substrate. So it was established which cells of the stomach contain pepsinogen, from which the enzyme pepsin is obtained.

Now another method is widely used that allows you to establish the localization of enzymes - separation centrifugation. To do this, the tissue under study (for example, pieces of the liver of laboratory animals) is crushed, and then a slurry is prepared from it in a sucrose solution. The mixture is transferred into test tubes and rotated at high speeds in centrifuges. Various cellular elements, depending on their mass and size, are distributed in a dense solution of sucrose during rotation approximately as follows:

To obtain heavy nuclei, relatively little acceleration (lower number of revolutions) is required. After separation of the nuclei, by increasing the number of revolutions, mitochondria and microsomes are successively precipitated, and cytoplasm is obtained. Now the activity of enzymes can be studied in each of the isolated fractions. It turns out that most of the known enzymes are localized predominantly in one or another fraction. For example, the enzyme aldolase is localized in the cytoplasm, and the enzyme that oxidizes caproic acid is located mainly in mitochondria.

If the membrane into which the enzymes are embedded is damaged, complex interrelated processes do not occur, i.e., each enzyme can act only on its own.

Plant and microorganism cells, like animal cells, contain very similar cell fractions. For example, plant plastids resemble mitochondria in terms of enzyme set. Microorganisms contain grains that resemble ribosomes and also contain large amounts of ribonucleic acid. Enzymes that are part of animal, plant and microbial cells have a similar effect. For example, hyaluronidase makes it easier for microbes to enter the body, contributing to the destruction of the cell wall. The same enzyme is found in various tissues of animal organisms.

Obtaining and using enzymes

Enzymes are found in all tissues of animals and plants. However, the amount of the same enzyme in different tissues and the strength of the enzyme-tissue bond are not the same. Therefore, in practice, its receipt is not always justified.

The digestive juices of humans and animals can be a source of enzymes. There are relatively few foreign impurities, cellular elements and other components in juices, which must be disposed of when obtaining a pure drug. These are almost pure solutions of enzymes.

It is more difficult to obtain the enzyme from tissues. To do this, the tissue is crushed, the cellular structures are destroyed by rubbing the crushed tissue with sand, or treated with ultrasound. At the same time, enzymes “fall out” of cells and membrane structures. They are now purified and separated from each other. For purification, the different ability of enzymes to separate on chromatographic columns, their unequal mobility in an electric field, their precipitation with alcohol, salts, acetone, and other methods are used. Since most enzymes are associated with the nucleus, mitochondria, ribosomes or other subcellular structures, this fraction is first isolated by centrifugation, and then the enzyme is extracted from it

The development of new purification methods has made it possible to obtain a number of crystalline enzymes in very pure form, which can be stored for years.

It is no longer possible to establish when people first used the enzyme, but it can be stated with great certainty that it was a plant-based enzyme. People have long paid attention to the usefulness of a particular plant, not only as a food product. For example, the natives of the Antilles have long used the juice of the melon tree to treat ulcers and other skin diseases.

Let us consider in more detail the features of the production and application of enzymes using the example of one of the now well-known plant biocatalysts - papain. This enzyme is found in the milky juice in all parts of the tropical papaya fruit tree - a giant tree-like grass that reaches 10 m. Its fruits are similar in shape and taste to melons and contain a large amount of papain enzyme. As early as the beginning of the 16th century. Spanish navigators discovered this plant in natural conditions in Central America. Then he was brought to India, and from there to all tropical countries. Vasco da Gama, who saw papaya in India, called it the golden tree of life, and Marco Polo said that papaya is "a melon that climbed a tree." Sailors knew that the fruits of the tree saved from scurvy and dysentery.

In our country, papaya grows on the Black Sea coast of the Caucasus, in the botanical garden of the Russian Academy of Sciences in special greenhouses. The raw material for the enzyme - milky juice - is obtained from incisions on the skin of the fruit. Then the juice is dried in the laboratory in vacuum ovens at low temperatures (no more than 80 °C). The dried product is triturated and stored in a sterile package filled with paraffin. This is already quite an active drug. Its enzymatic activity can be estimated by the amount of casein protein split per unit of time. For one biological unit of papain activity, such an amount of enzyme is taken that, when introduced into the blood, is sufficient to cause the symptom of “hanging ears” to appear in a rabbit weighing 1 kg. This phenomenon occurs because papain begins to act on the collagen protein filaments in the rabbit's ears.

Papain has a whole range of properties: proteolytic, anti-inflammatory, anticoagulant (preventing blood clotting), dehydration, analgesic and bactericidal. It breaks down proteins into polypeptides and amino acids. Moreover, this splitting goes deeper than under the action of other enzymes of animal and bacterial origin. A feature of papain is its ability to be active in a wide pH range and at large temperature fluctuations, which is especially important and convenient for the widespread use of this enzyme. And if we also take into account that in order to obtain enzymes similar in action to papain (pepsin, trypsin, lidase), blood, liver, muscles or other animal tissues are required, then the advantage and economic efficiency of the plant papain enzyme are undeniable.

The areas of application of papain are very diverse. In medicine, it is used to treat wounds, where it promotes the breakdown of proteins in damaged tissues and cleans the wound surface. Papain is indispensable in the treatment of various eye diseases. It causes the resorption of the clouded structures of the organ of vision, making them transparent. The positive effect of the enzyme in diseases of the digestive system is known. Good results have been obtained with the use of papain for the treatment of skin diseases, burns, as well as in neuropathology, urology and other branches of medicine.

In addition to medicine, a large amount of this enzyme is consumed in winemaking and brewing. Papain increases the shelf life of drinks. When processed with papain, the meat becomes soft and quickly digestible, the shelf life of products increases dramatically. Wool, going to the textile industry, after treatment with papain, does not curl and is not accompanied by shrinkage. Recently, papain has been used in the leather industry. Leather products after enzyme treatment become soft, elastic, stronger and more durable.

Careful study of some previously incurable diseases has led to the need to introduce missing enzymes into the body to replace those whose activity is reduced. It would be possible to introduce into the body the required amount of missing enzymes or to "add" the molecules of those enzymes that have reduced their catalytic activity in an organ or tissue. But the body reacts to these enzymes as if they were foreign proteins, rejects them, produces antibodies against them, which ultimately leads to the rapid breakdown of the introduced proteins. The expected therapeutic effect will not be. It is also impossible to introduce enzymes with food, since the digestive juices will “digest” them and they will lose their activity, decompose into amino acids, before reaching the cells and tissues. The introduction of enzymes directly into the bloodstream leads to their destruction by tissue proteases. These difficulties can be eliminated by using immobilized enzymes. The principle of immobilization is based on the ability of enzymes to "attach" to a stable carrier of an organic or inorganic nature. An example of the chemical binding of an enzyme to a matrix (carrier) is the formation of strong covalent bonds between their functional groups. The matrix can be, for example, a porous glass containing functional amino groups, to which the enzyme is chemically “attached”.

When using enzymes, it often becomes necessary to compare their activities. How to find out a more active enzyme? How to calculate the activity of different purified preparations? We agreed to take the amount of substrate as the activity of the enzyme, which in one minute can convert 1 g of tissue containing this enzyme at 25 °C. The more substrate processed by the enzyme, the more active it is. The activity of the same enzyme changes due to age, gender, time of day, body condition, and also depends on the endocrine glands that produce hormones.

Nature is almost never wrong in producing the same proteins throughout the life of an organism and passing on this strict information about the production of the same proteins from generation to generation. However, sometimes an altered protein appears in the body, in which one or more “extra” amino acids occur, or, conversely, they are lost. Many such molecular errors are currently known. They are due to various reasons and can cause painful changes in the body. Such diseases, which are caused by abnormal protein molecules, are called molecular diseases in medicine. For example, the hemoglobin of a healthy person, consisting of two polypeptide chains (a and b), and the hemoglobin of a patient with sickle cell anemia (erythrocyte has the shape of a sickle) differ only in that in patients with β-chain, glutamic acid is replaced by valine. Sickle cell anemia is a hereditary disease. Changes in hemoglobin are passed from parents to offspring.

Diseases that occur when the activity of enzymes changes are called fermentopathies. They are usually inherited, passed down from parents to children. For example, in congenital phenylketonuria, the following transformation is disturbed:

With a lack of the enzyme phenylalanine hydroxylase, phenylalanine does not turn into tyrosine, but accumulates, which causes a disorder in the normal function of a number of organs, primarily a disorder in the function of the central nervous system. The disease develops from the first days of a child's life, and by six to seven months of life, its first symptoms appear. In the blood and urine of such patients, huge amounts of phenylalanine can be found compared to the norm. Timely detection of such a pathology and a decrease in the intake of food that contains a lot of phenylalanine has a positive therapeutic effect.

Another example: the lack of an enzyme in children that converts galactose into glucose leads to the accumulation of galactose in the body, which accumulates in large quantities in tissues and affects the liver, kidneys, and eyes. If the absence of the enzyme is detected in a timely manner, then the child is transferred to a diet that does not contain galactose. This leads to the disappearance of signs of the disease.

Due to the existence of enzyme preparations, the structure of proteins and nucleic acids is deciphered. Without them, the production of antibiotics, winemaking, baking, and the synthesis of vitamins are impossible. In agriculture, growth stimulants are used, which have an effect on the activation of enzymatic processes. Many drugs that suppress or activate the activity of enzymes in the body have the same property.

Without enzymes, it is impossible to imagine the development of such promising areas as the reproduction of chemical processes occurring in the cell and the creation of modern industrial biotechnology on this basis. So far, not a single modern chemical plant is able to compete with an ordinary plant leaf, in whose cells, with the participation of enzymes and sunlight, a huge number of various complex organic substances are synthesized from water and carbon dioxide. At the same time, oxygen is released into the atmosphere in large quantities, which is so necessary for us to live.

Fermentology is a young and promising science that has separated from biology and chemistry and promises many amazing discoveries to everyone who decides to take it seriously.

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Often, along with vitamins, minerals and other elements useful for the human body, substances called enzymes are mentioned. What are enzymes and what function do they perform in the body, what is their nature and where are they located?

These are substances of protein nature, biocatalysts. Without them, there would be no baby food, ready-made cereals, kvass, cheese, cheese, yogurt, kefir. They affect the functioning of all systems of the human body. Insufficient or excessive activity of these substances adversely affects health, so you need to know what enzymes are in order to avoid problems caused by their lack.

What it is?

Enzymes are protein molecules synthesized by living cells. There are more than a hundred of them in each cell. The role of these substances is colossal. They influence the course of the rate of chemical reactions at a temperature that is suitable for a given organism. Another name for enzymes is biological catalysts. An increase in the rate of a chemical reaction occurs by facilitating its course. As catalysts, they are not consumed during the reaction and do not change its direction. The main functions of enzymes are that without them all reactions would proceed very slowly in living organisms, and this would noticeably affect viability.

For example, when chewing foods that contain starch (potatoes, rice), a sweetish taste appears in the mouth, which is associated with the work of amylase, an enzyme that breaks down starch present in saliva. By itself, starch is tasteless, as it is a polysaccharide. Its cleavage products (monosaccharides) have a sweet taste: glucose, maltose, dextrins.

All are divided into simple and complex. The former consist only of protein, while the latter consist of protein (apoenzyme) and non-protein (coenzyme) parts. Vitamins of groups B, E, K can be coenzymes.

Enzyme classes

Traditionally, these substances are divided into six groups. The name was originally given to them depending on the substrate on which a certain enzyme acts, by adding the ending -ase to its root. So, those enzymes that hydrolyze proteins (proteins) began to be called proteinases, fats (lipos) - lipases, starch (amilon) - amylases. Then the enzymes that catalyze similar reactions received names that indicate the type of the corresponding reaction - acylases, decarboxylases, oxidases, dehydrogenases, and others. Most of these names are still in use today.

Later, the International Biochemical Union introduced a nomenclature according to which the name and classification of enzymes should correspond to the type and mechanism of the chemical reaction catalyzed. This step brought relief in the systematization of data that relate to various aspects of metabolism. Reactions and the enzymes that catalyze them are divided into six classes. Each class consists of several subclasses (4-13). The first part of the name of the enzyme corresponds to the name of the substrate, the second - to the type of catalyzed reaction with the ending -aza. Each enzyme according to the classification (CF) has its own code number. The first digit corresponds to the reaction class, the next to the subclass, and the third to the subsubclass. The fourth digit indicates the number of the enzyme in order in its subclass. For example, if the EC is 2.7.1.1, then the enzyme belongs to the 2nd class, 7th subclass, 1st subclass. The last number refers to the enzyme hexokinase.

Meaning

If we talk about what enzymes are, we cannot ignore the question of their significance in the modern world. They are widely used in almost all branches of human activity. Such their prevalence is due to the fact that they are able to preserve their unique properties outside living cells. In medicine, for example, enzymes of the groups of lipases, proteases, and amylases are used. They break down fats, proteins, starch. As a rule, this type is part of such drugs as Panzinorm, Festal. These funds are primarily used to treat diseases of the gastrointestinal tract. Some enzymes are able to dissolve blood clots in blood vessels, they help in the treatment of purulent wounds. Enzyme therapy occupies a special place in the treatment of oncological diseases.

Due to its ability to break down starch, the enzyme amylase is widely used in the food industry. In the same area, lipases are used, which break down fats and proteases, which break down proteins. Amylase enzymes are used in brewing, winemaking and baking. In the preparation of ready-made cereals and to soften meat, proteases are used. In the production of cheese, lipases and rennet are used. The cosmetics industry also cannot do without them. They are part of washing powders, creams. In washing powders, for example, amylase, which breaks down starch, is added. Protein impurities and proteins are broken down by proteases, and lipases clean the tissue of oil and fat.

The role of enzymes in the body

Two processes are responsible in the human body for metabolism: anabolism and catabolism. The first ensures the absorption of energy and essential substances, the second - the breakdown of waste products. The constant interaction of these processes affects the absorption of carbohydrates, proteins and fats and the maintenance of the body's vital functions. Metabolic processes are regulated by three systems: nervous, endocrine and circulatory. They can function normally with the help of a chain of enzymes, which in turn ensure that a person adapts to changes in the conditions of the external and internal environment. Enzymes contain both protein and non-protein products.

In the process of biochemical reactions in the body, in the course of which enzymes take part, they themselves are not consumed. Each of them has its own chemical structure and its own unique role, so each initiates only a certain reaction. Biochemical catalysts help the rectum, lungs, kidneys, liver remove toxins and waste products from the body. They also contribute to the construction of skin, bones, nerve cells, muscle tissues. Specific enzymes are used to oxidize glucose.

All enzymes in the body are divided into metabolic and digestive. Metabolic are involved in the neutralization of toxins, the production of proteins and energy, and accelerate biochemical processes in cells. So, for example, superoxide dismutase is the strongest antioxidant, which is found naturally in most green plants, white cabbage, Brussels sprouts and broccoli, in wheat germ, greens, barley.

Enzyme activity

In order for these substances to fully perform their functions, certain conditions are necessary. Their activity is primarily affected by temperature. With increased, the rate of chemical reactions increases. As a result of the increase in the speed of the molecules, they are more likely to collide with each other, and the possibility of a reaction, therefore, increases. The optimal temperature provides the greatest activity. Due to the denaturation of proteins, which occurs when the optimal temperature deviates from the norm, the rate of a chemical reaction decreases. When the freezing point temperature is reached, the enzyme does not denature, but is inactivated. The quick freezing method, which is widely used for long-term storage of products, stops the growth and development of microorganisms, followed by inactivation of the enzymes that are inside. As a result, food does not decompose.

The activity of enzymes is also affected by the acidity of the environment. They work at neutral pH. Only some of the enzymes work in alkaline, strongly alkaline, acidic, or strongly acidic environments. For example, rennet breaks down proteins in the highly acidic environment of the human stomach. The enzyme can be affected by inhibitors and activators. Some ions, for example, metals, activate them. Other ions have a suppressive effect on the activity of enzymes.

Hyperactivity

Excessive activity of enzymes has its consequences for the functioning of the whole organism. First, it provokes an increase in the rate of enzyme action, which in turn causes a deficiency of the reaction substrate and the formation of an excess of the chemical reaction product. Deficiency of substrates and the accumulation of these products significantly worsens the state of health, disrupts the vital activity of the body, causes the development of diseases and can result in the death of a person. The accumulation of uric acid, for example, leads to gout and kidney failure. Due to the lack of substrate, there will be no excess product. This only works if one and the other can be dispensed with.

There are several reasons for the excess activity of enzymes. The first is a gene mutation; it can be congenital or acquired under the influence of mutagens. The second factor is an excess of a vitamin or trace element in water or food, which is necessary for the enzyme to work. An excess of vitamin C, for example, through the increased activity of collagen synthesis enzymes, disrupts the mechanisms of wound healing.

Hypoactivity

Both increased and decreased activity of enzymes negatively affects the activity of the body. In the second case, a complete cessation of activity is possible. This state dramatically reduces the rate of the chemical reaction of the enzyme. As a result, the accumulation of the substrate is complemented by a deficiency of the product, which leads to serious complications. Against the background of disturbances in the vital activity of the body, the state of health worsens, diseases develop, and there may be a fatal outcome. Accumulation of ammonia or deficiency of ATP leads to death. Oligophrenia develops due to the accumulation of phenylalanine. The principle also applies here that in the absence of an enzyme substrate, there will be no accumulation of the reaction substrate. A bad effect on the body has a condition in which blood enzymes do not perform their functions.

Several causes of hypoactivity are considered. Mutation of genes, congenital or acquired - this is the first. The condition can be corrected with the help of gene therapy. You can try to exclude substrates of the missing enzyme from food. In some cases this may help. The second factor is the lack of a vitamin or trace element in the food necessary for the enzyme to work. The following causes are impaired vitamin activation, amino acid deficiency, acidosis, the appearance of inhibitors in the cell, protein denaturation. Enzyme activity also decreases with a decrease in body temperature. Some factors affect the function of all types of enzymes, while others affect only certain types.

Digestive enzymes

A person enjoys the process of eating and sometimes ignores the fact that the main task of digestion is the transformation of food into substances that can become a source of energy and building material for the body, being absorbed into the intestines. Protein enzymes contribute to this process. Digestive substances are produced by the digestive organs, which are involved in the process of splitting food. The action of enzymes is necessary in order to obtain the necessary carbohydrates, fats, amino acids from food, which is the necessary nutrients and energy for the normal functioning of the body.

In order to normalize impaired digestion, it is recommended to simultaneously use the necessary protein substances with meals. When overeating, you can take 1-2 tablets after or during meals. Pharmacies sell a large number of different enzyme preparations that help improve digestion. They should be stocked up when taking one type of nutrient. For problems with chewing or swallowing food, it is necessary to take enzymes with meals. Significant reasons for their use can also be such diseases as acquired and congenital fermentopathy, irritable bowel syndrome, hepatitis, cholangitis, cholecystitis, pancreatitis, colitis, chronic gastritis. Enzyme preparations should be taken along with drugs that affect the digestive process.

Enzymopathology

In medicine, there is a whole section that deals with the search for a connection between a disease and the lack of synthesis of a particular enzyme. This is the field of enzymology - enzymopathology. Insufficient enzyme synthesis is also to be considered. For example, the hereditary disease phenylketonuria develops against the background of the loss of the ability of liver cells to synthesize this substance, which catalyzes the conversion of phenylalanine into tyrosine. Symptoms of this disease are disorders of mental activity. Due to the gradual accumulation of toxic substances in the body, the patient is disturbed by such signs as vomiting, anxiety, increased irritability, lack of interest in anything, severe fatigue.

At the birth of a child, the pathology does not manifest itself. Primary symptoms can be noticed between the ages of two and six months. The second half of the baby's life is characterized by a pronounced lag in mental development. In 60% of patients, idiocy develops, less than 10% are limited to a mild degree of oligophrenia. Cell enzymes do not cope with their functions, but this can be corrected. Timely diagnosis of pathological changes can stop the development of the disease until puberty. Treatment consists in limiting the intake of phenylalanine with food.

Enzyme preparations

Answering the question of what enzymes are, two definitions can be noted. The first is biochemical catalysts, and the second is preparations that contain them. They are able to normalize the state of the environment in the stomach and intestines, ensure the breakdown of final products to microparticles, and improve the absorption process. They also prevent the emergence and development of gastroenterological diseases. The most famous of the enzymes is the drug Mezim Forte. In its composition, it has lipase, amylase, protease, which help reduce pain in chronic pancreatitis. Capsules are taken as a replacement treatment for insufficient production of the necessary enzymes by the pancreas.

These drugs are mainly taken with food. The number of capsules or tablets is prescribed by the doctor, based on the identified violations of the absorption mechanism. It is better to store them in the refrigerator. With prolonged use of digestive enzymes, addiction does not occur, and this does not affect the work of the pancreas. When choosing a drug, you should pay attention to the date, the ratio of quality and price. Enzyme preparations are recommended for chronic diseases of the digestive system, overeating, periodic stomach problems, and food poisoning. Most often, doctors prescribe the Mezim tablet preparation, which has proven itself well in the domestic market and confidently holds its position. There are other analogues of this drug, no less famous and more than affordable. In particular, many prefer Pacreatin or Festal tablets, which have the same properties as more expensive counterparts.

The life of any organism is possible due to the metabolic processes occurring in it. These reactions are controlled by natural catalysts, or enzymes. Another name for these substances is enzymes. The term "enzymes" comes from the Latin fermentum, which means "sourdough". The concept appeared historically in the study of fermentation processes.

Rice. 1 - Fermentation using yeast - a typical example of an enzymatic reaction

Mankind has long enjoyed the beneficial properties of these enzymes. For example, cheese has been made from milk using rennet for many centuries.

Enzymes differ from catalysts in that they act in a living organism, while catalysts - in inanimate nature. The branch of biochemistry that studies these essential substances for life is called enzymology.

General properties of enzymes

Enzymes are protein molecules that interact with various substances, accelerating their chemical transformation along a certain path. However, they are not consumed. Each enzyme has an active site that attaches to a substrate and a catalytic site that starts a particular chemical reaction. These substances accelerate the biochemical reactions occurring in the body without raising the temperature.

The main properties of enzymes:

• specificity: the ability of an enzyme to act only on a specific substrate, for example, lipases on fats;
• catalytic efficiency: the ability of enzymatic proteins to accelerate biological reactions hundreds and thousands of times;
• ability to regulate: in each cell, the production and activity of enzymes is determined by a peculiar chain of transformations that affects the ability of these proteins to be synthesized again.

The role of enzymes in the human body cannot be overestimated. At that time, when the structure of DNA had just been discovered, it was said that one gene is responsible for the synthesis of one protein, which already determines some particular trait. Now this statement sounds like this: "One gene - one enzyme - one trait." That is, without the activity of enzymes in the cell, life cannot exist.

Classification

Depending on the role in chemical reactions, the following classes of enzymes are distinguished:

In a living organism, all enzymes are divided into intra- and extracellular. Intracellular include, for example, liver enzymes involved in the neutralization reactions of various substances that come with the blood. They are found in the blood when an organ is damaged, which helps in the diagnosis of its diseases.

Intracellular enzymes that are markers of damage to internal organs:

• liver - alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, sorbitol dehydrogenase;
• kidneys - alkaline phosphatase;
• prostate - acid phosphatase;
• cardiac muscle - lactate dehydrogenase

Extracellular enzymes are secreted by glands into the external environment. The main ones are secreted by the cells of the salivary glands, gastric wall, pancreas, intestines and are actively involved in digestion.

Digestive enzymes

Digestive enzymes are proteins that speed up the breakdown of large molecules that make up food. They divide such molecules into smaller fragments that are easier for cells to digest. The main types of digestive enzymes are proteases, lipases, and amylases.

The main digestive gland is the pancreas. It produces most of these enzymes, as well as nucleases that cleave DNA and RNA, and peptidases involved in the formation of free amino acids. Moreover, a small amount of enzymes formed is able to "process" a large amount of food.

During the enzymatic breakdown of nutrients, energy is released, which is consumed for metabolic processes and vital activity. Without the participation of enzymes, such processes would occur too slowly, not providing the body with a sufficient energy supply.

In addition, the participation of enzymes in the process of digestion ensures the breakdown of nutrients into molecules that can pass through the cells of the intestinal wall and enter the bloodstream.

Amylase

Amylase is produced by the salivary glands. It acts on food starch, which is made up of a long chain of glucose molecules. As a result of the action of this enzyme, sections are formed consisting of two connected glucose molecules, that is, fructose, and other short-chain carbohydrates. They are further metabolized to glucose in the intestines and from there absorbed into the blood.

The salivary glands break down only part of the starch. Salivary amylase is active for a short time while food is being chewed. After entering the stomach, the enzyme is inactivated by its acidic contents. Most of the starch is already broken down in the duodenum by the action of pancreatic amylase, produced by the pancreas.

Rice. 2 - Amylase starts the breakdown of starch

Short carbohydrates formed under the action of pancreatic amylase enter the small intestine. Here, with the help of maltase, lactase, sucrase, dextrinase, they are broken down into glucose molecules. Fiber that is not degraded by enzymes is excreted from the intestines with feces.

Proteases

Proteins or proteins are an essential part of the human diet. For their splitting enzymes - proteases are necessary. They differ in the site of synthesis, substrates, and other characteristics. Some of them are active in the stomach, such as pepsin. Others are produced by the pancreas and are active in the intestinal lumen. In the gland itself, an inactive enzyme precursor, chymotrypsinogen, is released, which begins to act only after mixing with acidic food contents, turning into chymotrypsin. This mechanism helps to avoid self-damage by proteases of pancreatic cells.

Rice. 3 - Enzymatic cleavage of proteins

Proteases break down food proteins into smaller fragments - polypeptides. Enzymes - peptidases break them down to amino acids that are absorbed in the intestines.

Lipases

Dietary fats are broken down by lipase enzymes, which are also produced by the pancreas. They break down fat molecules into fatty acids and glycerol. Such a reaction requires the presence in the lumen of the duodenum of bile, which is formed in the liver.

Rice. 4 - Enzymatic hydrolysis of fats

The role of replacement therapy with Mikrazim

For many people with digestive disorders, especially those with pancreatic diseases, the administration of enzymes provides functional support for the organ and speeds up the healing process. After stopping an attack of pancreatitis or another acute situation, the intake of enzymes can be stopped, as the body independently restores their secretion.

Long-term use of enzymatic preparations is necessary only in case of severe exocrine pancreatic insufficiency.

One of the most physiological in its composition is the drug "Mikrazim". It consists of amylase, protease and lipase contained in pancreatic juice. Therefore, there is no need to separately select which enzyme should be used for various diseases of this organ.

Indications for the use of this medication:

• chronic pancreatitis, cystic fibrosis and other causes of insufficient secretion of pancreatic enzymes;
• inflammatory diseases of the liver, stomach, intestines, especially after operations on them, for faster recovery of the digestive system;
• nutritional errors;
• violation of the function of chewing, for example, with dental diseases or immobility of the patient.

Taking digestive enzymes for replacement purposes helps to avoid bloating, loose stools, and abdominal pain. In addition, in severe chronic diseases of the pancreas, Micrasim completely assumes the function of splitting nutrients. Therefore, they can be freely absorbed in the intestines. This is especially important for children with cystic fibrosis.

Important: before use, read the instructions or consult your doctor.