The variable fragment of an amino acid molecule is called. General formula of amino acids. What happens to amino acids and proteins in your body

Organic (carboxylic) acids containing, as a rule, one or two amino groups (NH2). Depending on the position of the amino group in the carbon chain in relation to the carboxyl, a, b, y, etc. are distinguished. A. are widespread in nature: a A., ... ... Biological encyclopedic dictionary

AMINO ACIDS, a class of organic compounds containing carboxyl (COOH) and amino groups (NH2); have the properties of both acids and bases. Participate in the metabolism of nitrogenous substances in all organisms (initial compounds in the biosynthesis of hormones,... ... Modern encyclopedia

A class of organic compounds containing carboxyl (COOH) and amino groups (NH2); have the properties of both acids and bases. Participate in the metabolism of nitrogenous substances in all organisms (the initial compound in the biosynthesis of hormones, vitamins,... ... Big Encyclopedic Dictionary

AMINO ACIDS, from, units. amino acid, s, female (specialist.). A class of organic compounds that have the properties of both acids and bases. | adj. amino acid, oh, oh. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

Org. compounds with a dual function, acidic, due to the presence of a carboxyl group (see Carboxyl), and basic, associated with the presence of an amino group (NH2) or (less often) an imino group (NH), which is usually part of the heterocycle. Examples... Geological encyclopedia

amino acids- organic compounds containing one or two amino groups; derivatives of carboxylic acids in which the hydrogen in the radical is replaced by an amino group; structural units of a protein molecule. protein: alanine. arginine asparagine proline aspartic... ... Ideographic Dictionary of the Russian Language

amino acids- - carboxylic acids in which at least one carbon atom of the hydrocarbon chain is replaced by an amino group ... A brief dictionary of biochemical terms

AMINO ACIDS- AMINO ACIDS, organic acids (containing the COOH group), in which one or more H atoms in the alcohol radical are replaced by alkaline amino groups (NHa), as a result of which A. belong to the group. amphoteric compounds. Depending on the… … Great Medical Encyclopedia

Amino acids- * amino acids * amino acids are a class of organic compounds that are characterized by the properties of both carboxylic acids and amines (table). They differ from each other in the chemical nature of the side chains (groups). Based on the polarity of groups, A. can... Genetics. encyclopedic Dictionary

AMINO ACIDS- a class of organic compounds whose molecules contain amino groups (NH2) and carboxyl groups (COOH). A. are widespread in nature and are part of protein molecules. All A. are solid crystalline substances, soluble in water... ... Big Polytechnic Encyclopedia

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• , Orekhov S.N.. The textbook provides information about modern methods of obtaining medical drugs in the conditions of industrial biopharmaceutical production. The greatest attention is paid...
• Pharmaceutical biotechnology. Guide to practical exercises, S. N. Orekhov. The study guide provides information about modern methods for obtaining medications in industrial biopharmaceutical production conditions. The greatest attention is paid...

Amino acids are heterofunctional compounds that necessarily contain two functional groups: an amino group - NH 2 and a carboxyl group - COOH, associated with a hydrocarbon radical. The general formula of the simplest amino acids can be written as follows:

Because amino acids contain two different functional groups that influence each other, the characteristic reactions differ from those of carboxylic acids and amines.

Properties of amino acids

The amino group - NH 2 determines the basic properties of amino acids, since it is capable of attaching a hydrogen cation to itself via a donor-acceptor mechanism due to the presence of a free electron pair at the nitrogen atom.

The -COOH group (carboxyl group) determines the acidic properties of these compounds. Therefore, amino acids are amphoteric organic compounds. They react with alkalis as acids:

With strong acids - like bases - amines:

In addition, the amino group in an amino acid interacts with its carboxyl group, forming an internal salt:

The ionization of amino acid molecules depends on the acidic or alkaline nature of the environment:

Since amino acids in aqueous solutions behave like typical amphoteric compounds, in living organisms they play the role of buffer substances that maintain a certain concentration of hydrogen ions.

Amino acids are colorless crystalline substances that melt and decompose at temperatures above 200 °C. They are soluble in water and insoluble in ether. Depending on the R- radical, they can be sweet, bitter or tasteless.

Amino acids are divided into natural (found in living organisms) and synthetic. Among natural amino acids (about 150), proteinogenic amino acids (about 20) are distinguished, which are part of proteins. They are L-shapes. About half of these amino acids are irreplaceable, because they are not synthesized in the human body. Essential acids are valine, leucine, isoleucine, phenylalanine, lysine, threonine, cysteine, methionine, histidine, tryptophan. These substances enter the human body with food. If their quantity in food is insufficient, the normal development and functioning of the human body is disrupted. In certain diseases, the body is unable to synthesize some other amino acids. Thus, in phenylketonuria, tyrosine is not synthesized. The most important property of amino acids is the ability to enter into molecular condensation with the release of water and the formation of the amide group -NH-CO-, for example:

The high-molecular compounds obtained as a result of this reaction contain a large number of amide fragments and are therefore called polyamides.

These, in addition to the synthetic nylon fiber mentioned above, include, for example, enant, formed during the polycondensation of aminoenanthic acid. Amino acids with amino and carboxyl groups at the ends of the molecules are suitable for producing synthetic fibers.

Alpha amino acid polyamides are called peptides. Depending on the number of amino acid residues, they are distinguished dipeptides, tripeptides, polypeptides. In such compounds, the -NH-CO- groups are called peptide groups.

Isomerism and nomenclature of amino acids

Amino acid isomerism is determined by the different structure of the carbon chain and the position of the amino group, for example:

The names of amino acids are also widespread, in which the position of the amino group is indicated by the letters of the Greek alphabet: α, β, y, etc. Thus, 2-aminobutanoic acid can also be called an α-amino acid:

Methods for obtaining amino acids

Amino acids are the structural chemical units or "building blocks" that make up proteins. Amino acids consist of 16% nitrogen, this is their main chemical difference from the other two essential nutrients - carbohydrates and fats. The importance of amino acids for the body is determined by the enormous role that proteins play in all life processes.

Every living organism, from the largest animals to tiny microbes, is made up of proteins. Various forms of proteins take part in all processes occurring in living organisms. In the human body, muscles, ligaments, tendons, all organs and glands, hair, and nails are formed from proteins. Proteins are found in fluids and bones. Enzymes and hormones that catalyze and regulate all processes in the body are also proteins. A deficiency of these nutrients in the body can lead to an imbalance in water balance, which causes swelling.

Each protein in the body is unique and exists for specific purposes. Proteins are not interchangeable. They are synthesized in the body from amino acids, which are formed as a result of the breakdown of proteins found in foods. Thus, it is amino acids, and not proteins themselves, that are the most valuable nutritional elements. In addition to the fact that amino acids form proteins that make up the tissues and organs of the human body, some of them act as neurotransmitters (neurotransmitters) or are their precursors.

Neurotransmitters are chemicals that transmit nerve impulses from one nerve cell to another. Thus, some amino acids are essential for normal brain function. Amino acids ensure that vitamins and minerals adequately perform their functions. Some amino acids directly provide energy to muscle tissue.

In the human body, many amino acids are synthesized in the liver. However, some of them cannot be synthesized in the body, so a person must obtain them from food. These essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Amino acids that are synthesized in the liver: alanine, arginine, asparagine, aspartic acid, citrulline, cysteine, gamma-aminobutyric acid, glutamine and glutamic acid, glycine, ornithine, proline, serine, taurine, tyrosine.

The process of protein synthesis occurs constantly in the body. If at least one essential amino acid is missing, protein formation stops. This can lead to a variety of serious problems, from poor digestion to depression and slow growth.

How does this situation arise? Easier than you might imagine. Many factors lead to this, even if your diet is balanced and you consume enough protein. Malabsorption in the gastrointestinal tract, infection, injury, stress, certain medications, the aging process and imbalances of other nutrients in the body can all lead to essential amino acid deficiencies.

Keep in mind that all of the above does not mean that consuming a lot of protein will solve any problems. In reality, it is not conducive to maintaining health.

Excess protein creates additional stress for the kidneys and liver, which need to process the products of protein metabolism, the main one being ammonia. It is very toxic to the body, so the liver immediately processes it into urea, which then travels through the bloodstream to the kidneys, where it is filtered and excreted.

As long as the amount of protein is not too high and the liver is functioning well, the ammonia is neutralized immediately and does not cause any harm. But if there is too much of it and the liver cannot cope with its neutralization (as a result of poor diet, digestive disorders and/or liver disease), toxic levels of ammonia are created in the blood. In this case, a lot of serious health problems can arise, including hepatic encephalopathy and coma.

Too high a concentration of urea also causes kidney damage and back pain. Therefore, it is not the quantity, but the quality of proteins consumed in food that is important. Currently, it is possible to obtain essential and non-essential amino acids in the form of biologically active food supplements.

This is especially important for various diseases and when using reduction diets. Vegetarians need supplements containing essential amino acids to ensure that the body receives everything it needs for normal protein synthesis.

There are different types of amino acid supplements available. Amino acids are part of some multivitamins and protein mixtures. There are commercially available formulas containing complexes of amino acids or containing one or two amino acids. They come in various forms: capsules, tablets, liquids and powders.

Most amino acids exist in two forms, the chemical structure of one being a mirror image of the other. These are called D- and L-forms, for example D-cystine and L-cystine.

D stands for dextra (right in Latin) and L stands for levo (left). These terms indicate the direction of rotation of the helix, which is the chemical structure of a given molecule. Proteins in animal and plant organisms are created mainly by L-forms of amino acids (with the exception of phenylalanine, which is represented by D, L forms).

Nutritional supplements containing L-amino acids are considered more suitable for the biochemical processes of the human body.
Free, or unbound, amino acids are the purest form. Therefore, when choosing an amino acid supplement, preference should be given to products containing L-crystalline amino acids standardized by the American Pharmacopoeia (USP). They do not require digestion and are absorbed directly into the bloodstream. After oral administration, they are absorbed very quickly and, as a rule, do not cause allergic reactions.

Individual amino acids are taken on an empty stomach, preferably in the morning or between meals with a small amount of vitamins B6 and C. If you are taking a complex of amino acids that includes all the essential ones, it is best to do this 30 minutes after or 30 minutes before meals. It is best to take both individual essential amino acids and a complex of amino acids, but at different times. Amino acids alone should not be taken for long periods of time, especially in high doses. It is recommended to take it for 2 months with a 2-month break.

Alanin

Alanine helps normalize glucose metabolism. A relationship has been established between excess alanine and infection with the Epstein-Barr virus, as well as chronic fatigue syndrome. One form of alanine, beta-alanine is a component of pantothenic acid and coenzyme A, one of the most important catalysts in the body.

Arginine

Arginine slows down the growth of tumors, including cancer, by stimulating the body's immune system. It increases the activity and size of the thymus gland, which produces T lymphocytes. In this regard, arginine is useful for people suffering from HIV infection and malignant neoplasms.

It is also used for liver diseases (cirrhosis and fatty degeneration), it promotes detoxification processes in the liver (primarily the neutralization of ammonia). Seminal fluid contains arginine, so it is sometimes used in the complex treatment of infertility in men. Connective tissue and skin also contain large amounts of arginine, so taking it is effective for various injuries. Arginine is an important component of metabolism in muscle tissue. It helps maintain optimal nitrogen balance in the body, as it participates in the transportation and neutralization of excess nitrogen in the body.

Arginine helps with weight loss because it causes a slight decrease in fat stores in the body.

Arginine is part of many enzymes and hormones. It has a stimulating effect on the production of insulin by the pancreas as a component of vasopressin (a pituitary hormone) and helps in the synthesis of growth hormone. Although arginine is synthesized in the body, its production may be reduced in newborns. Sources of arginine include chocolate, coconuts, dairy products, gelatin, meat, oats, peanuts, soybeans, walnuts, white flour, wheat and wheat germ.

People who have viral infections, including Herpes simplex, should not take arginine supplements and should avoid consuming foods rich in arginine. Pregnant and breastfeeding mothers should not take arginine supplements. Taking small doses of arginine is recommended for diseases of the joints and connective tissue, impaired glucose tolerance, liver diseases and injuries. Long-term use is not recommended.

Asparagine

Asparagine is necessary to maintain balance in the processes occurring in the central nervous system: it prevents both excessive excitation and excessive inhibition. It is involved in the processes of amino acid synthesis in the liver.

Since this amino acid increases vitality, a supplement based on it is used for fatigue. It also plays an important role in metabolic processes. Aspartic acid is often prescribed for diseases of the nervous system. It is useful for athletes, as well as for liver dysfunction. In addition, it stimulates the immune system by increasing the production of immunoglobulins and antibodies.

Aspartic acid is found in large quantities in plant proteins obtained from sprouted seeds and in meat products.

Carnitine

Strictly speaking, carnitine is not an amino acid, but its chemical structure is similar to that of amino acids, and therefore they are usually considered together. Carnitine is not involved in protein synthesis and is not a neurotransmitter. Its main function in the body is the transport of long-chain fatty acids, the oxidation of which releases energy. This is one of the main sources of energy for muscle tissue. Thus, carnitine increases the conversion of fat into energy and prevents the deposition of fat in the body, primarily in the heart, liver, and skeletal muscles.

Carnitine reduces the likelihood of developing diabetes complications associated with lipid metabolism disorders, slows down fatty liver degeneration in chronic alcoholism and the risk of heart disease. It has the ability to reduce triglyceride levels in the blood, promotes weight loss and increases muscle strength in patients with neuromuscular diseases and enhances the antioxidant effect of vitamins C and E.

Some variants of muscular dystrophy are believed to be associated with carnitine deficiency. With such diseases, people should receive more of this substance than is required according to the norms.

It can be synthesized in the body in the presence of iron, thiamine, pyridoxine and the amino acids lysine and methionine. Carnitine synthesis occurs in the presence of sufficient amounts of vitamin C. Insufficient amounts of any of these nutrients in the body leads to carnitine deficiency. Carnitine enters the body with food, primarily meat and other products of animal origin.

Most cases of carnitine deficiency are associated with a genetically determined defect in the process of its synthesis. Possible manifestations of carnitine deficiency include impaired consciousness, heart pain, muscle weakness, and obesity.

Men, due to their larger muscle mass, require more carnitine than women. Vegetarians are more likely to be deficient in this nutrient than non-vegetarians due to the fact that carnitine is not found in plant-based proteins.

Moreover, methionine and lysine (amino acids necessary for carnitine synthesis) are also not found in sufficient quantities in plant foods.

To get the required amount of carnitine, vegetarians should take supplements or eat lysine-fortified foods such as cornflakes.

Carnitine is presented in dietary supplements in various forms: in the form of D, L-carnitine, D-carnitine, L-carnitine, acetyl-L-carnitine.
It is preferable to take L-carnitine.

Citrulline

Citrulline is predominantly found in the liver. It increases energy supply, stimulates the immune system, and is converted into L-arginine during metabolism. It neutralizes ammonia, which damages liver cells.

Cysteine ​​and cystine

These two amino acids are closely related, each cystine molecule consists of two cysteine ​​molecules connected to each other. Cysteine ​​is very unstable and easily transforms into L-cystine, and thus one amino acid can easily change into another when needed.

Both amino acids are sulfur-containing amino acids and play an important role in the formation of skin tissue and are important for detoxification processes. Cysteine ​​is part of alpha keratin - the main protein of nails, skin and hair. It promotes collagen formation and improves skin elasticity and texture. Cysteine ​​is also found in other proteins in the body, including some digestive enzymes.

Cysteine ​​helps neutralize certain toxic substances and protects the body from the damaging effects of radiation. It is one of the most powerful antioxidants, and its antioxidant effect is enhanced when taken simultaneously with vitamin C and selenium.

Cysteine ​​is a precursor to glutathione, a substance that has a protective effect on liver and brain cells from damage by alcohol, certain medications and toxic substances contained in cigarette smoke. Cysteine ​​dissolves better than cystine and is utilized more quickly in the body, which is why it is often used in the complex treatment of various diseases. This amino acid is formed in the body from L-methionine, with the obligatory presence of vitamin B6.

Additional intake of cysteine ​​is necessary for rheumatoid arthritis, arterial diseases, and cancer. It accelerates recovery after operations, burns, binds heavy metals and soluble iron. This amino acid also accelerates fat burning and muscle tissue formation.

L-cysteine ​​has the ability to destroy mucus in the respiratory tract, which is why it is often used for bronchitis and emphysema. It accelerates healing processes in respiratory diseases and plays an important role in activating leukocytes and lymphocytes.

Since this substance increases the amount of glutathione in the lungs, kidneys, liver and red bone marrow, it slows down the aging process, for example, reducing the number of age spots. N-acetylcysteine ​​is more effective at increasing glutathione levels in the body than cystine or even glutathione itself.

People with diabetes should be careful when taking cysteine ​​supplements as it has the ability to inactivate insulin. If you have cystinuria, a rare genetic condition that leads to the formation of cystine stones, you should not take cysteine.

Dimethylglycine

Dimethylglycine is a derivative of glycine, the simplest amino acid. It is a constituent of many important substances, such as the amino acids methionine and choline, some hormones, neurotransmitters and DNA.

Dimethylglycine is found in small quantities in meat products, seeds and grains. Although there are no symptoms associated with dimethylglycine deficiency, taking dimethylglycine supplements has a number of benefits, including improved energy and mental performance.

Dimethylglycine also stimulates the immune system, reduces cholesterol and triglycerides in the blood, helps normalize blood pressure and glucose levels, and also helps normalize the function of many organs. It is also used for epileptic seizures.

Gamma-aminobutyric acid

Gamma-aminobutyric acid (GABA) functions as a neurotransmitter in the central nervous system in the body and is essential for metabolism in the brain. It is formed from another amino acid - glutamine. It reduces neuronal activity and prevents overexcitation of nerve cells.

Gamma-aminobutyric acid relieves anxiety and has a calming effect; it can also be taken as tranquilizers, but without the risk of addiction. This amino acid is used in the complex treatment of epilepsy and arterial hypertension. Since it has a relaxing effect, it is used in the treatment of sexual dysfunctions. In addition, GABA is prescribed for attention deficit disorder. Excess gamma-aminobutyric acid, however, can increase anxiety, causing shortness of breath and trembling of the limbs.

Glutamic acid

Glutamic acid is a neurotransmitter that transmits impulses in the central nervous system. This amino acid plays an important role in carbohydrate metabolism and promotes the penetration of calcium through the blood-brain barrier.

This amino acid can be used by brain cells as an energy source. It also neutralizes ammonia by removing nitrogen atoms in the process of forming another amino acid - glutamine. This process is the only way to neutralize ammonia in the brain.

Glutamic acid is used in the correction of behavioral disorders in children, as well as in the treatment of epilepsy, muscular dystrophy, ulcers, hypoglycemic conditions, complications of insulin therapy for diabetes mellitus and mental development disorders.

Glutamine

Glutamine is the amino acid most commonly found in free form in muscles. It very easily penetrates the blood-brain barrier and in brain cells passes into glutamic acid and vice versa, in addition, it increases the amount of gamma-aminobutyric acid, which is necessary to maintain normal brain function.

This amino acid also maintains normal acid-base balance in the body and a healthy gastrointestinal tract, and is necessary for the synthesis of DNA and RNA.

Glutamine is an active participant in nitrogen metabolism. Its molecule contains two nitrogen atoms and is formed from glutamic acid by adding one nitrogen atom. Thus, glutamine synthesis helps remove excess ammonia from tissues, primarily from the brain, and transport nitrogen within the body.

Glutamine is found in large quantities in muscles and is used to synthesize proteins in skeletal muscle cells. Therefore, nutritional supplements with glutamine are used by bodybuilders and in various diets, as well as to prevent muscle loss in diseases such as malignant neoplasms and AIDS, after operations and during long-term bed rest.

Additionally, glutamine is also used in the treatment of arthritis, autoimmune diseases, fibrosis, gastrointestinal diseases, peptic ulcers, and connective tissue diseases.

This amino acid improves brain activity and is therefore used for epilepsy, chronic fatigue syndrome, impotence, schizophrenia and senile dementia. L-glutamine reduces pathological cravings for alcohol, therefore it is used in the treatment of chronic alcoholism.

Glutamine is found in many foods of both plant and animal origin, but it is easily destroyed by heating. Spinach and parsley are good sources of glutamine, as long as they are consumed raw.

Dietary supplements containing glutamine should only be stored in a dry place, otherwise glutamine will convert into ammonia and pyroglutamic acid. Do not take glutamine if you have liver cirrhosis, kidney disease, or Reye's syndrome.

Glutathione

Glutathione, like carnitine, is not an amino acid. According to its chemical structure, it is a tripeptide obtained in the body from cysteine, glutamic acid and glycine.

Glutathione is an antioxidant. Most glutathione is found in the liver (some of it is released directly into the bloodstream), as well as in the lungs and gastrointestinal tract.

It is necessary for carbohydrate metabolism, and also slows down aging due to its effect on lipid metabolism and prevents the occurrence of atherosclerosis. Glutathione deficiency primarily affects the nervous system, causing problems with coordination, mental processes, and tremors.

The amount of glutathione in the body decreases with age. In this regard, older people should receive it additionally. However, it is preferable to use nutritional supplements containing cysteine, glutamic acid and glycine - that is, substances that synthesize glutathione. Taking N-acetylcysteine ​​is considered the most effective.

Glycine

Glycine slows down the degeneration of muscle tissue, as it is a source of creatine, a substance contained in muscle tissue and used in the synthesis of DNA and RNA. Glycine is necessary for the synthesis of nucleic acids, bile acids and non-essential amino acids in the body.

It is part of many antacid medications used for stomach diseases; it is useful for restoring damaged tissue, as it is found in large quantities in the skin and connective tissue.

This amino acid is necessary for the normal functioning of the central nervous system and the maintenance of good prostate health. It functions as an inhibitory neurotransmitter and thus can prevent epileptic seizures.

Glycine is used in the treatment of manic-depressive psychosis, and it can also be effective for hyperactivity. Excess glycine in the body causes a feeling of fatigue, but an adequate amount provides the body with energy. If necessary, glycine can be converted into serine in the body.

Histidine

Histidine is an essential amino acid that promotes tissue growth and repair, is part of the myelin sheaths that protect nerve cells, and is also necessary for the formation of red and white blood cells. Histidine protects the body from the damaging effects of radiation, promotes the removal of heavy metals from the body and helps with AIDS.

Too high a histidine content can lead to stress and even mental disorders (agitation and psychosis).

Inadequate levels of histidine in the body worsen the condition of rheumatoid arthritis and deafness associated with damage to the auditory nerve. Methionine helps lower the level of histidine in the body.

Histamine, a very important component of many immunological reactions, is synthesized from histidine. It also promotes sexual arousal. In this regard, the simultaneous use of dietary supplements containing histidine, niacin and pyridoxine (necessary for the synthesis of histamine) may be effective for sexual disorders.

Since histamine stimulates the secretion of gastric juice, the use of histidine helps with digestive disorders associated with low acidity of gastric juice.

People suffering from manic depression should not take histidine unless a deficiency of this amino acid is clearly established. Histidine is found in rice, wheat and rye.

Isoleucine

Isoleucine is one of the BCAA amino acids and essential amino acids necessary for the synthesis of hemoglobin. It also stabilizes and regulates blood sugar levels and energy supply processes. Isoleucine metabolism occurs in muscle tissue.

Combined use with isoleucine and valine (BCAA) increases endurance and promotes muscle tissue recovery, which is especially important for athletes.

Isoleucine is necessary for many mental illnesses. A deficiency of this amino acid results in symptoms similar to hypoglycemia.

Food sources of isoleucine include almonds, cashews, chicken, chickpeas, eggs, fish, lentils, liver, meat, rye, most seeds, and soy proteins.

There are biologically active food supplements containing isoleucine. In this case, it is necessary to maintain the correct balance between isoleucine and two other branched BCAA amino acids - leucine and valine.

Leucine

Leucine is an essential amino acid, together with isoleucine and valine, one of the three branched BCAA amino acids. Acting together, they protect muscle tissue and are sources of energy, and also promote the restoration of bones, skin, and muscles, so their use is often recommended during the recovery period after injuries and operations.

Leucine also slightly lowers blood sugar levels and stimulates the release of growth hormone. Food sources of leucine include brown rice, beans, meat, nuts, soy flour and wheat flour.

Dietary supplements containing leucine are used in combination with valine and isoleucine. They should be taken with caution to avoid causing hypoglycemia. Excess leucine can increase the amount of ammonia in the body.

Lysine

Lysine is an essential amino acid that is part of almost any protein. It is necessary for normal bone formation and growth in children, promotes the absorption of calcium and maintains normal nitrogen metabolism in adults.

This amino acid is involved in the synthesis of antibodies, hormones, enzymes, collagen formation and tissue repair. Lysine is used during the recovery period after operations and sports injuries. It also lowers serum triglyceride levels.

Lysine has an antiviral effect, especially against viruses that cause herpes and acute respiratory infections. Taking supplements containing lysine in combination with vitamin C and bioflavonoids is recommended for viral diseases.

A deficiency of this essential amino acid can lead to anemia, hemorrhages in the eyeball, enzyme disorders, irritability, fatigue and weakness, poor appetite, slow growth and weight loss, as well as reproductive system disorders.

Food sources of lysine include cheese, eggs, fish, milk, potatoes, red meat, soy and yeast products.

Methionine

Methionine is an essential amino acid that helps process fats, preventing their deposition in the liver and on the walls of arteries. The synthesis of taurine and cysteine ​​depends on the amount of methionine in the body. This amino acid promotes digestion, provides detoxification processes (primarily the neutralization of toxic metals), reduces muscle weakness, protects against radiation exposure, and is useful for osteoporosis and chemical allergies.

This amino acid is used in complex therapy of rheumatoid arthritis and toxicosis of pregnancy. Methionine has a pronounced antioxidant effect, as it is a good source of sulfur, which inactivates free radicals. It is used for Gilbert's syndrome and liver dysfunction. Methionine is also necessary for the synthesis of nucleic acids, collagen and many other proteins. It is useful for women receiving oral hormonal contraceptives. Methionine lowers histamine levels in the body, which may be useful in schizophrenia when the amount of histamine is elevated.

Methionine in the body is converted into cysteine, which is a precursor to glutathione. This is very important in case of poisoning, when large amounts of glutathione are required to neutralize toxins and protect the liver.

Food sources of methionine: legumes, eggs, garlic, lentils, meat, onions, soybeans, seeds and yogurt.

Ornithine

Ornithine helps release growth hormone, which helps burn fat in the body. This effect is enhanced when ornithine is used in combination with arginine and carnitine. Ornithine is also essential for the immune system and liver function, participating in detoxification processes and the restoration of liver cells.

Ornithine in the body is synthesized from arginine and, in turn, serves as a precursor for citrulline, proline, and glutamic acid. High concentrations of ornithine are found in the skin and connective tissue, so this amino acid helps repair damaged tissue.

Dietary supplements containing ornithine should not be given to children, pregnant and nursing mothers, or to persons with a history of schizophrenia.

Phenylalanine

Phenylalanine is an essential amino acid. In the body, it can be converted into another amino acid - tyrosine, which, in turn, is used in the synthesis of two main neurotransmitters: dopamine and norepinephrine. Therefore, this amino acid affects mood, reduces pain, improves memory and learning ability, and suppresses appetite. It is used in the treatment of arthritis, depression, menstrual pain, migraines, obesity, Parkinson's disease and schizophrenia.

Phenylalanine is found in three forms: L-phenylalanine (the natural form and it is the one that is part of most proteins in the human body), D-phenylalanine (a synthetic mirror form, has an analgesic effect), DL-phenylalanine (combines the beneficial properties of the two previous forms, it is usually used for premenstrual syndrome.

Dietary supplements containing phenylalanine should not be given to pregnant women, persons with anxiety attacks, diabetes, high blood pressure, phenylketonuria, or pigmented melanoma.

Proline

Proline improves skin condition by increasing collagen production and reducing its loss with age. Helps restore cartilaginous surfaces of joints, strengthens ligaments and heart muscle. To strengthen connective tissue, proline is best used in combination with vitamin C.

Proline enters the body mainly from meat products.

Serin

Serine is necessary for the normal metabolism of fats and fatty acids, the growth of muscle tissue and the maintenance of a normal immune system.

Serine is synthesized in the body from glycine. As a moisturizing agent, it is included in many cosmetic products and dermatological preparations.

Taurine

Taurine is found in high concentrations in the heart muscle, white blood cells, skeletal muscles, and the central nervous system. It is involved in the synthesis of many other amino acids, and is also a major component of bile, which is necessary for the digestion of fats, the absorption of fat-soluble vitamins and for maintaining normal blood cholesterol levels.

Therefore, taurine is useful for atherosclerosis, edema, heart disease, arterial hypertension and hypoglycemia. Taurine is necessary for the normal metabolism of sodium, potassium, calcium and magnesium. It prevents the removal of potassium from the heart muscle and therefore helps prevent certain heart rhythm disorders. Taurine has a protective effect on the brain, especially during dehydration. It is used in the treatment of anxiety and agitation, epilepsy, hyperactivity, and seizures.

Dietary supplements with taurine are given to children with Down syndrome and muscular dystrophy. In some clinics, this amino acid is included in complex therapy for breast cancer. Excessive excretion of taurine from the body occurs in various conditions and metabolic disorders.

Arrhythmias, disorders of platelet formation, candidiasis, physical or emotional stress, intestinal diseases, zinc deficiency and alcohol abuse lead to taurine deficiency in the body. Alcohol abuse also impairs the body's ability to absorb taurine.

In diabetes, the body's need for taurine increases, and vice versa, taking dietary supplements containing taurine and cystine reduces the need for insulin. Taurine is found in eggs, fish, meat, milk, but is not found in plant proteins.

It is synthesized in the liver from cysteine ​​and from methionine in other organs and tissues of the body, provided there is a sufficient amount of vitamin B6. In case of genetic or metabolic disorders that interfere with the synthesis of taurine, it is necessary to take a dietary supplement with this amino acid.

Threonine

Threonine is an essential amino acid that helps maintain normal protein metabolism in the body. It is important for the synthesis of collagen and elastin, helps the liver and is involved in fat metabolism in combination with aspartic acid and methionine.

Threonine is found in the heart, central nervous system, skeletal muscles and prevents the deposition of fats in the liver. This amino acid stimulates the immune system as it promotes the production of antibodies. Threonine is found in very small quantities in grains, so vegetarians are more likely to be deficient in this amino acid.

Tryptophan

Tryptophan is an essential amino acid required for the production of niacin. It is used to synthesize serotonin, one of the most important neurotransmitters, in the brain. Tryptophan is used for insomnia, depression and to stabilize mood.

It helps with hyperactivity disorder in children, is used for heart disease, to control body weight, reduce appetite, and also to increase the release of growth hormone. Helps with migraine attacks, helps reduce the harmful effects of nicotine. Deficiency of tryptophan and magnesium can increase spasms of the coronary arteries.

The richest food sources of tryptophan include brown rice, country cheese, meat, peanuts and soy protein.

Tyrosine

Tyrosine is a precursor to the neurotransmitters norepinephrine and dopamine. This amino acid is involved in mood regulation; a lack of tyrosine leads to a deficiency of norepinephrine, which in turn leads to depression. Tyrosine suppresses appetite, helps reduce fat storage, promotes melatonin production and improves adrenal, thyroid and pituitary function.

Tyrosine is also involved in phenylalanine metabolism. Thyroid hormones are formed when iodine atoms are added to tyrosine. It is therefore not surprising that low plasma tyrosine is associated with hypothyroidism.

Symptoms of tyrosine deficiency also include low blood pressure, low body temperature and restless leg syndrome.

Dietary supplements with tyrosine are used to relieve stress and are believed to help with chronic fatigue syndrome and narcolepsy. They are used for anxiety, depression, allergies and headaches, as well as for drug withdrawal. Tyrosine may be helpful in Parkinson's disease. Natural sources of tyrosine include almonds, avocados, bananas, dairy products, pumpkin seeds and sesame seeds.

Tyrosine can be synthesized from phenylalanine in the human body. Dietary supplements with phenylalanine are best taken before bed or with foods containing large amounts of carbohydrates.

During treatment with monoamine oxidase inhibitors (usually prescribed for depression), you should almost completely avoid foods containing tyrosine and not take dietary supplements with tyrosine, as this can lead to an unexpected and sharp rise in blood pressure.

Valin

Valine is an essential amino acid with a stimulating effect, one of the BCAA amino acids, and therefore can be used by muscles as an energy source. Valine is necessary for muscle metabolism, repair of damaged tissues and for maintaining normal nitrogen metabolism in the body.

Valine is often used to correct severe amino acid deficiencies resulting from drug addiction. Its excessively high level in the body can lead to symptoms such as paresthesia (pins and needles sensation) and even hallucinations.
Valine is found in the following foods: grains, meat, mushrooms, dairy products, peanuts, soy protein.

Valine supplementation should be balanced with the other branched chain amino acids BCAA L-leucine and L-isoleucine.

Properties of amino acids can be divided into two groups: chemical and physical.

Chemical properties of amino acids

Depending on the compounds, amino acids can exhibit different properties.

Amino acid interactions:

Amino acids, as amphoteric compounds, form salts with both acids and alkalis.

As carboxylic acids, amino acids form functional derivatives: salts, esters, amides.

Interaction and properties of amino acids with reasons:
Salts are formed:

NH 2 -CH 2 -COOH + NaOH NH 2 -CH 2 -COONa + H2O

Sodium salt + 2-aminoacetic acid Sodium salt of aminoacetic acid (glycine) + water

Interaction with alcohols:

Amino acids can react with alcohols in the presence of hydrogen chloride gas, turning into ester. Amino acid esters do not have a bipolar structure and are volatile compounds.

NH 2 -CH 2 -COOH + CH 3 OH NH 2 -CH 2 -COOCH 3 + H 2 O.

Methyl ester / 2-aminoacetic acid /

Interaction ammonia:

Amides are formed:

NH 2 -CH(R)-COOH + H-NH 2 = NH 2 -CH(R)-CONH 2 + H 2 O

Interaction of amino acids with strong acids:

We get salts:

HOOC-CH 2 -NH 2 + HCl → Cl (or HOOC-CH 2 -NH 2 *HCl)

These are the basic chemical properties of amino acids.

Physical properties of amino acids

Let us list the physical properties of amino acids:

• Colorless
• Have a crystalline form
• Most amino acids have a sweet taste, but depending on the radical (R), they can be bitter or tasteless
• Easily soluble in water, but poorly soluble in many organic solvents
• Amino acids have the property of optical activity
• Melts with decomposition at temperatures above 200°C
• Non-volatile
• Aqueous solutions of amino acids in acidic and alkaline environments conduct electric current

All natural amino acids can be divided into the following main groups:

1) aliphatic saturated amino acids(glycine, alanine);

2) sulfur-containing amino acids(cysteine);

3) amino acids with an aliphatic hydroxyl group(serine);

4) aromatic amino acids(phenylalanine, tyrosine);

5) amino acids with acid radical(glutamic acid);

6) amino acids with a basic radical(lysine).

Isomerism. In all a-amino acids, except glycine, the a-carbon atom is connected to four different substituents, so all these amino acids can exist in the form of two isomers, which are mirror images of each other.

Receipt. 1. Hydrolysis of proteins usually produces complex mixtures of amino acids. However, a number of methods have been developed that make it possible to obtain individual pure amino acids from complex mixtures.

2. Replacement of halogen with amino group in the corresponding halogen acids. This method of obtaining amino acids is completely analogous to obtaining amines from halogen derivatives of alkanes and ammonia:

Physical properties. Amino acids are solid crystalline substances, highly soluble in water and slightly soluble in organic solvents. Many amino acids have a sweet taste. They melt at high temperatures and usually decompose in the process. They cannot go into a vapor state.

Chemical properties. Amino acids are organic amphoteric compounds. They contain two functional groups of opposite nature in the molecule: an amino group with basic properties and a carboxyl group with acidic properties. Amino acids react with both acids and bases:

When amino acids are dissolved in water, the carboxyl group removes a hydrogen ion, which can attach to the amino group. This creates internal salt, the molecule of which is a bipolar ion:

Acid-base transformations of amino acids in various environments can be represented by the following diagram:

Aqueous solutions of amino acids have a neutral, alkaline or acidic environment depending on the number of functional groups. Thus, glutamic acid forms an acidic solution (two -COOH groups, one -NH 2), lysine forms an alkaline solution (one -COOH group, two -NH 2).

Amino acids can react with alcohols in the presence of hydrogen chloride gas to form an ester:

The most important property of amino acids is their ability to condense to form peptides.

Peptides. Peptides. are the condensation products of two or more amino acid molecules. Two amino acid molecules can react with each other to eliminate a water molecule and form a product in which the fragments are linked peptide bond-CO-NH-.

The resulting compound is called a dipeptide. A dipeptide molecule, like amino acids, contains an amino group and a carboxyl group and can react with one more amino acid molecule:

The reaction product is called a tripeptide. The process of increasing the peptide chain can continue in principle indefinitely (polycondensation) and lead to substances with very high molecular weight (proteins).

The main property of peptides is the ability to hydrolyze. During hydrolysis, complete or partial cleavage of the peptide chain occurs and shorter peptides with lower molecular weight or α-amino acids that make up the chain are formed. Analysis of the products of complete hydrolysis allows us to determine the amino acid composition of the peptide. Complete hydrolysis occurs when the peptide is heated for a long time with concentrated hydrochloric acid.

Hydrolysis of peptides can occur in an acidic or alkaline environment, as well as under the action of enzymes. Amino acid salts are formed in acidic and alkaline environments:

Enzymatic hydrolysis is important because it occurs selectively, T . e. allows the cleavage of strictly defined sections of the peptide chain.

Qualitative reactions to amino acids. 1) All amino acids are oxidized ninhydrin with the formation of products colored blue-violet. This reaction can be used to quantify amino acids by spectrophotometry. 2) When aromatic amino acids are heated with concentrated nitric acid, nitration of the benzene ring occurs and yellow-colored compounds are formed. This reaction is called xanthoprotein(from Greek xanthos - yellow).

Squirrels. Proteins are natural polypeptides with high molecular weights (from 10,000 to tens of millions). They are part of all living organisms and perform a variety of biological functions.

Structure. Four levels can be distinguished in the structure of the polypeptide chain. The primary structure of a protein is a specific sequence of amino acids in a polypeptide chain. The peptide chain has a linear structure in only a small number of proteins. In most proteins, the peptide chain is folded in a certain way in space.

Secondary structure is the conformation of the polypeptide chain, i.e. the way the chain is twisted in space due to hydrogen bonds between NH and CO groups. The main method of laying a chain is a spiral.

The tertiary structure of a protein is a three-dimensional configuration of a twisted helix in space. The tertiary structure is formed due to disulfide bridges -S-S- between cysteine ​​residues located in different places of the polypeptide chain. Also involved in the formation of the tertiary structure ionic interactions oppositely charged groups NH 3 + and COO- and hydrophobic interactions, i.e., the tendency of the protein molecule to fold so that the hydrophobic hydrocarbon residues are inside the structure.

Tertiary structure is the highest form of spatial organization of proteins. However, some proteins (for example, hemoglobin) have quaternary structure, which is formed due to the interaction between different polypeptide chains.

Physical properties proteins are very diverse and are determined by their structure. Based on their physical properties, proteins are divided into two classes: globular proteins dissolve in water or form colloidal solutions, fibrillar proteins insoluble in water.

Chemical properties. 1 . The destruction of the secondary and tertiary structure of a protein while maintaining the primary structure is called denaturation . It occurs when heated, changes in the acidity of the environment, or exposure to radiation. An example of denaturation is the coagulation of egg whites when eggs are boiled. Denaturation can be reversible or irreversible. Irreversible denaturation can be caused by the formation of insoluble substances when proteins are exposed to salts of heavy metals - lead or mercury.

2. Protein hydrolysis is the irreversible destruction of the primary structure in an acidic or alkaline solution with the formation of amino acids. By analyzing hydrolysis products, it is possible to determine the quantitative composition of proteins.

3. For proteins, several are known qualitative reactions. All compounds containing a peptide bond give a violet color when exposed to copper (II) salts in an alkaline solution. This reaction is called biuret. Proteins containing aromatic amino acid residues (phenylalanine, tyrosine) give a yellow color when exposed to concentrated nitric acid (xanthoprotein reaction).

Biological significance of proteins:

1. Absolutely all chemical reactions in the body occur in the presence of catalysts - enzymes. All known enzymes are protein molecules. Proteins are very powerful and selective catalysts. They speed up reactions millions of times, and each reaction has its own single enzyme.

2. Some proteins perform transport functions and transport molecules or ions to sites of synthesis or accumulation. For example, the protein contained in the blood hemoglobin carries oxygen to tissues, and protein myoglobin stores oxygen in muscles.

3. Proteins are the building blocks of cells. Supporting, muscle, and integumentary tissues are built from them.

4. Proteins play an important role in the body's immune system. There are specific proteins (antibodies), which are able to recognize and bind foreign objects - viruses, bacteria, foreign cells.

5. Receptor proteins perceive and transmit signals coming from neighboring cells or from the environment. For example, the effect of light on the retina of the eye is perceived by the photoreceptor rhodopsin. Receptors activated by low molecular weight substances such as acetylcholine transmit nerve impulses at the junctions of nerve cells.

From the above list of functions of proteins, it is clear that proteins are vital for any organism and are, therefore, the most important component of food. During the digestion process, proteins are hydrolyzed to amino acids, which serve as the starting material for the synthesis of proteins necessary for a given organism. There are amino acids that the body is not able to synthesize itself and acquires them only with food. These amino acids are called irreplaceable.

Lecture: General information about polymers and their classification.