What are amino acids and how to take them correctly. Amino acids and protein biosynthesis The main properties of amino acids are determined by the presence
In an acidic environment, α-amino acids act as bases (according to the amino group), and in an alkaline environment they act as acids (according to the carboxyl group). In some amino acids, the radical (R) can also be ionized, in connection with which all amino acids can be divided into charged and uncharged (at a physiological pH value of 6.0 - 8.0) (see Table 4). As an example of the former, aspartic acid and lysine can be given:
If the amino acid radicals are neutral, they do not affect the dissociation of the α-carboxyl or α-amino group, and the pK values (the negative logarithm indicating the pH value at which these groups are half dissociated) remain relatively constant.
The pK values for the α-carboxy (pK 1) and α-amino group (pK 2) differ greatly. At pH< pK 1 почти все молекулы аминокислоты протежированы и заряжены положительно. Напротив, при рН >pK 2 almost all amino acid molecules are negatively charged, since the α-carboxyl group is in a dissociated state.
Therefore, depending on the pH of the medium, amino acids have a total zero positive or negative charge. The pH value at which the total charge of the molecule is zero, and it does not move in the electric field either to the cathode or to the anode, is called the isoelectric point and is denoted by pI.
For neutral α-amino acids, the pI value is found as the arithmetic mean between two pK values:
When the pH of the solution is less than pI, the amino acids are protonated and, being positively charged, move in the electric field to the cathode. The reverse picture is observed at pH > pI.
For amino acids containing charged (acid or basic) radicals, the isoelectric point depends on the acidity or basicity of these radicals and their pK (pK 3). The pI value for them is found by the following formulas:
for acidic amino acids:
for basic amino acids:
In the cells and intercellular fluid of the human and animal body, the pH of the environment is close to neutral, so the basic amino acids (lysine, arginine) have a positive charge (cations), acidic amino acids (aspartic, glutamine) have a negative charge (anions), and the rest exist in the form of a bipolar zwitterion.
Stereochemistry of amino acids
An important feature of protein α-amino acids is their optical activity. With the exception of glycine, all of them are built asymmetrically, and therefore, being dissolved in water or hydrochloric acid, they are able to rotate the plane of polarization of light. Amino acids exist as spatial isomers belonging to the D- or L-series. The L- or D-configuration is determined by the type of structure of the compound relative to the asymmetric carbon atom (a carbon atom bonded to four different atoms or groups of atoms). In formulas, an asymmetric carbon atom is denoted by an asterisk. Figure 3 shows projection models of L- and D-configurations of amino acids, which are, as it were, a mirror image of each other. All 18 optically active protein amino acids belong to the L-series. However, D-amino acids have been found in the cells of many microorganisms and in the antibiotics produced by some of them.
Rice. 3. Configuration of L- and D- amino acids
The structure of proteins
Based on the results of studying the products of protein hydrolysis and put forward by A.Ya. Danilevsky's ideas about the role of peptide bonds -CO-NH- in the construction of a protein molecule, the German scientist E. Fischer proposed at the beginning of the 20th century the peptide theory of the structure of proteins. According to this theory, proteins are linear polymers of α-amino acids linked by a peptide bond - polypeptides:
In each peptide, one terminal amino acid residue has a free α-amino group (N-terminus) and the other has a free α-carboxyl group (C-terminus). The structure of peptides is usually depicted starting from the N-terminal amino acid. In this case, amino acid residues are indicated by symbols. For example: Ala-Tyr-Leu-Ser-Tyr- - Cys. This entry denotes a peptide in which the N-terminal α-amino acid is lyatsya alanine, and the C-terminal - cysteine. When reading such a record, the endings of the names of all acids, except for the last ones, change to - "yl": alanyl-tyrosyl-leucyl-seryl-tyrosyl--cysteine. The length of the peptide chain in peptides and proteins found in the body ranges from two to hundreds and thousands of amino acid residues.
To determine the amino acid composition, proteins (peptides) are subjected to hydrolysis:
In a neutral environment, this reaction proceeds very slowly, but is accelerated in the presence of acids or alkalis. Protein hydrolysis is usually carried out in a sealed ampoule in a 6M hydrochloric acid solution at 105°C; under such conditions, complete disintegration occurs in about a day. In some cases, the protein is hydrolyzed under milder conditions (at a temperature of 37-40 °C) under the action of biological enzyme catalysts for several hours.
Then the amino acids of the hydrolyzate are separated by chromatography on ion-exchange resins (sulfopolystyrene cation exchanger), isolating separately the fraction of each amino acid. To wash out amino acids from the ion exchange column, buffers with increasing pH are used. Aspartate, which has an acidic side chain, is removed first; arginine with the main side chain is washed out last. The sequence of removal of amino acids from the column is determined by the washout profile of standard amino acids. Fractionated amino acids are determined by the color formed when heated with ninhydrin:
In this reaction, colorless ninhydrin is converted; to a blue-violet product whose color intensity (at 570 nm) is proportional to the amount of amino acid (only proline gives a yellow color). By measuring the staining intensity, it is possible to calculate the concentration of each amino acid in the hydrolyzate and the number of residues of each of them in the protein under study.
Currently, such an analysis is carried out with the help of automatic devices - amino acid analyzers (see Fig. Diagram of the device below). The device gives the result of the analysis in the form of a graph of the concentrations of individual amino acids. This method has found wide application in the study of the composition of nutrients, clinical practice; with its help, in 2-3 hours, you can get a complete picture of the qualitative composition of amino acids in products and biological fluids.
Rice. Scheme of an amino acid analyzer: 1 - washing solution (buffer with variable pH); 2 - chromatographic column (protein hydrolyzate is added to the upper part of the column, then leaching begins); 3 - ninhydrin solution; 4 - water bath (heating is necessary to accelerate the reaction of ninhydrin with amino acids); 5 - spectrophotometer and recording device; 6 - chromatogram, each peak of which corresponds to one amino acid, and the peak area is proportional to the amino acid concentration in the hydrolyzate.
Amino acids are the main building material of any living organism. By their nature, they are the primary nitrogenous substances of plants, which are synthesized from the soil. The structure of and and amino acids depend on their composition.
Amino acid structure
Each of its molecule has carboxyl and amine groups, which are connected to the radical. If an amino acid contains 1 carboxyl and 1 amino group, its structure can be denoted by the formula below.
Amino acids that have 1 acid and 1 alkaline group are called monoaminomonocarboxylic. In organisms are also synthesized and whose functions determine 2 carboxyl groups or 2 amine groups. Amino acids containing 2 carboxyl and 1 amino groups are called monoaminodicarboxylic, and those containing 2 amine and 1 carboxyl group are called diaminomonocarboxylic.
They also differ in the structure of the organic radical R. Each of them has its own name and structure. Hence the different functions of amino acids. It is the presence of acidic and alkaline groups that ensures its high reactivity. These groups connect amino acids and form a polymer - a protein. Proteins are also called polypeptides because of their structure.
Amino acids as a building material
A protein molecule is a chain of tens or hundreds of amino acids. Proteins differ in composition, quantity and order of amino acids, because the number of combinations of 20 components is almost infinite. Some of them have the entire composition of essential amino acids, while others do without one or more. Separate amino acids, the structure, the functions of which are similar to the proteins of the human body, are not used as food, as they are poorly soluble and do not break down the gastrointestinal tract. These include the proteins of nails, hair, wool or feathers.
The functions of amino acids cannot be overestimated. These substances are the main food in the diet of people. What is the function of amino acids? They increase the growth of muscle mass, help strengthen joints and ligaments, restore damaged body tissues and participate in all processes that occur in the human body.
Essential amino acids
Only supplements or foods can be obtained Functions in the formation of healthy joints, strong muscles, beautiful hair are very significant. These amino acids include:
- phenylalanine;
- lysine;
- threonine;
- methionine;
- valine;
- leucine;
- tryptophan;
- histidine;
- isoleucine.
Functions of essential amino acids
These bricks perform the most important functions in the work of every cell of the human body. They are imperceptible as long as they enter the body in sufficient quantities, but their deficiency significantly impairs the functioning of the whole organism.
- Valine renews muscles, serves as an excellent source of energy.
- Histidine improves blood composition, promotes muscle recovery and growth, improves joint function.
- Isoleucine helps produce hemoglobin. Controls the amount of sugar in the blood, increases a person's energy, endurance.
- Leucine strengthens the immune system, monitors the level of sugar and leukocytes in the blood. If the level of leukocytes is too high: it lowers them and connects the body's reserves to eliminate inflammation.
- Lysine helps calcium absorption, which forms and strengthens bones. Helps the production of collagen, improves hair structure. For men, this is an excellent anabolic, as it builds muscle and increases male strength.
- Methionine normalizes the functioning of the digestive system and liver. Participates in the breakdown of fats, removes toxicosis in pregnant women, and has a beneficial effect on hair.
- Threonine improves the functioning of the digestive tract. Increases immunity, participates in the creation of elastin and collagen. Threonine prevents the deposition of fat in the liver.
- Tryptophan is responsible for human emotions. Produces serotonin - the hormone of happiness, thereby normalizes sleep, improves mood. It tames the appetite, has a beneficial effect on the heart muscle and arteries.
- Phenylalanine serves as a transmitter of signals from nerve cells to the brain of the head. Improves mood, suppresses unhealthy appetite, improves memory, increases susceptibility, reduces pain.
A deficiency of essential amino acids leads to stunting, metabolic disorders, and a decrease in muscle mass.
Non-essential amino acids
These are amino acids, the structure and functions of which are produced in the body:
- arginine;
- alanine;
- asparagine;
- glycine;
- proline;
- taurine;
- tyrosine;
- glutamate;
- serine;
- glutamine;
- ornithine;
- cysteine;
- carnitine.
Functions of non-essential amino acids
- Cysteine eliminates toxic substances, is involved in the creation of skin and muscle tissues, and is a natural antioxidant.
- Tyrosine reduces physical fatigue, speeds up metabolism, eliminates stress and depression.
- Alanine serves for muscle growth, is a source of energy.
- increases metabolism and reduces the formation of ammonia at high loads.
- Cystine eliminates pain in case of injury to the ligaments and joints.
- is responsible for brain activity, during prolonged physical exertion it passes into glucose, producing energy.
- Glutamine restores muscles, improves immunity, speeds up metabolism, enhances brain function and creates growth hormone.
- Glycine is essential for muscle function, fat breakdown, blood pressure and blood sugar stabilization.
- Carnitine moves fatty acids into cells where they are broken down to release energy, resulting in excess fat being burned and energy being generated.
- Ornithine produces growth hormone, participates in the process of urination, breaks down fatty acids, and helps the production of insulin.
- Proline provides the production of collagen, it is necessary for ligaments and joints.
- Serine improves immunity and produces energy, is needed for the rapid metabolism of fatty acids and muscle growth.
- Taurine breaks down fat, raises the body's resistance, synthesizes bile salts.
Protein and its properties
Proteins, or proteins, are macromolecular compounds containing nitrogen. The concept of "protein", first designated by Berzelius in 1838, comes from the Greek word and means "primary", which reflects the leading value of proteins in nature. A variety of proteins makes it possible for the existence of a huge number of living beings: from bacteria to the human body. There are significantly more of them than other macromolecules, because proteins are the foundation of a living cell. They make up approximately 20% of the mass of the human body, more than 50% of the dry mass of the cell. Such a variety of proteins is due to the properties of twenty different amino acids that interact with each other and create polymer molecules.
An outstanding property of proteins is the ability to independently create a specific spatial structure characteristic of a particular protein. Proteins are biopolymers with peptide bonds. For the chemical composition of proteins, a constant average nitrogen content is characteristic - approximately 16%.
Life, as well as the growth and development of the body, is impossible without the function of protein amino acids to build new cells. Proteins cannot be replaced by other elements, their role in the human body is extremely important.
Functions of proteins
The need for proteins lies in the following functions:
- it is necessary for growth and development, as it acts as the main building material for the creation of new cells;
- controls metabolism, during which energy is released. After eating, the metabolic rate increases, for example, if the food consists of carbohydrates, the metabolism accelerates by 4%, if from proteins - by 30%;
- regulate in the body, due to its hydrophilicity - the ability to attract water;
- strengthen the immune system by synthesizing antibodies that protect against infection and eliminate the threat of disease.
Products - protein sources
Muscles and the human skeleton consist of living tissues that not only function, but are also updated throughout life. They recover from damage, retain their strength and durability. To do this, they require well-defined nutrients. Food provides the body with the energy needed for all processes, including muscle function, tissue growth and repair. And protein in the body is used both as a source of energy and as a building material.
Therefore, it is very important to observe its daily use in food. Protein-rich foods: chicken, turkey, lean ham, pork, beef, fish, shrimp, beans, lentils, bacon, eggs, nuts. All these foods provide the body with protein and provide the energy needed for life.
According to the nature of the hydrocarbon substituents, amines are divided into
General structural features of amines
As in the ammonia molecule, in the molecule of any amine, the nitrogen atom has an unshared electron pair directed to one of the vertices of the distorted tetrahedron:
For this reason, amines, like ammonia, have significantly pronounced basic properties.
So, amines, like ammonia, reversibly react with water, forming weak bases:
The bond of the hydrogen cation with the nitrogen atom in the amine molecule is realized using the donor-acceptor mechanism due to the lone electron pair of the nitrogen atom. Limit amines are stronger bases compared to ammonia, because. in such amines, hydrocarbon substituents have a positive inductive (+I) effect. In this regard, the electron density on the nitrogen atom increases, which facilitates its interaction with the H + cation.
Aromatic amines, if the amino group is directly connected to the aromatic nucleus, exhibit weaker basic properties compared to ammonia. This is due to the fact that the lone electron pair of the nitrogen atom is shifted towards the aromatic π-system of the benzene ring, as a result of which the electron density on the nitrogen atom decreases. In turn, this leads to a decrease in the basic properties, in particular the ability to interact with water. So, for example, aniline reacts only with strong acids, and practically does not react with water.
Chemical properties of saturated amines
As already mentioned, amines react reversibly with water:
Aqueous solutions of amines have an alkaline reaction of the environment, due to the dissociation of the resulting bases:
Saturated amines react with water better than ammonia due to their stronger basic properties.
The main properties of saturated amines increase in the series.
Secondary limiting amines are stronger bases than primary limiting amines, which in turn are stronger bases than ammonia. As for the basic properties of tertiary amines, when it comes to reactions in aqueous solutions, the basic properties of tertiary amines are much worse than those of secondary amines, and even slightly worse than those of primary ones. This is due to steric hindrances, which significantly affect the rate of amine protonation. In other words, three substituents "block" the nitrogen atom and prevent its interaction with H + cations.
Interaction with acids
Both free saturated amines and their aqueous solutions interact with acids. In this case, salts are formed:
Since the basic properties of saturated amines are more pronounced than those of ammonia, such amines react even with weak acids, such as carbonic:
Amine salts are solids that are highly soluble in water and poorly soluble in non-polar organic solvents. The interaction of amine salts with alkalis leads to the release of free amines, similar to how ammonia is displaced by the action of alkalis on ammonium salts:
2. Primary limiting amines react with nitrous acid to form the corresponding alcohols, nitrogen N 2 and water. For example:
A characteristic feature of this reaction is the formation of gaseous nitrogen, in connection with which it is qualitative for primary amines and is used to distinguish them from secondary and tertiary. It should be noted that most often this reaction is carried out by mixing the amine not with a solution of nitrous acid itself, but with a solution of a salt of nitrous acid (nitrite) and then adding a strong mineral acid to this mixture. When nitrites interact with strong mineral acids, nitrous acid is formed, which then reacts with an amine:
Secondary amines give oily liquids under similar conditions, the so-called N-nitrosamines, but this reaction does not occur in real USE tasks in chemistry. Tertiary amines do not react with nitrous acid.
Complete combustion of any amines leads to the formation of carbon dioxide, water and nitrogen:
Interaction with haloalkanes
It is noteworthy that exactly the same salt is obtained by the action of hydrogen chloride on a more substituted amine. In our case, during the interaction of hydrogen chloride with dimethylamine:
Getting amines:
1) Alkylation of ammonia with haloalkanes:
In the case of a lack of ammonia, instead of an amine, its salt is obtained:
2) Reduction by metals (to hydrogen in the activity series) in an acidic medium:
followed by treatment of the solution with alkali to release the free amine:
3) The reaction of ammonia with alcohols by passing their mixture through heated aluminum oxide. Depending on the proportions of alcohol / amine, primary, secondary or tertiary amines are formed:
Chemical properties of aniline
Aniline - the trivial name of aminobenzene, which has the formula:
As can be seen from the illustration, in the aniline molecule the amino group is directly connected to the aromatic ring. In such amines, as already mentioned, the basic properties are much less pronounced than in ammonia. So, in particular, aniline practically does not react with water and weak acids such as carbonic.
The interaction of aniline with acids
Aniline reacts with strong and moderately strong inorganic acids. In this case, phenylammonium salts are formed:
Reaction of aniline with halogens
As already mentioned at the very beginning of this chapter, the amino group in aromatic amines is drawn into the aromatic ring, which in turn reduces the electron density on the nitrogen atom, and as a result increases it in the aromatic nucleus. An increase in the electron density in the aromatic nucleus leads to the fact that electrophilic substitution reactions, in particular, reactions with halogens, proceed much more easily, especially in the ortho and para positions relative to the amino group. So, aniline easily interacts with bromine water, forming a white precipitate of 2,4,6-tribromaniline:
This reaction is qualitative for aniline and often allows you to determine it among other organic compounds.
The interaction of aniline with nitrous acid
Aniline reacts with nitrous acid, but due to the specificity and complexity of this reaction, it does not occur in the real exam in chemistry.
Aniline alkylation reactions
With the help of sequential alkylation of aniline at the nitrogen atom with halogen derivatives of hydrocarbons, secondary and tertiary amines can be obtained:
Obtaining aniline
1. Reduction of nitrobenzene with metals in the presence of strong non-oxidizing acids:
C 6 H 5 -NO 2 + 3Fe + 7HCl = + Cl- + 3FeCl 2 + 2H 2 O
Cl - + NaOH \u003d C 6 H 5 -NH 2 + NaCl + H 2 O
As metals, any metals that are up to hydrogen in the activity series can be used.
The reaction of chlorobenzene with ammonia:
C 6 H 5 -Cl + 2NH 3 → C 6 H 5 NH 2 + NH 4 Cl
Chemical properties of amino acids
Amino acids call compounds in the molecules of which there are two types of functional groups - amino (-NH 2) and carboxy- (-COOH) groups.
In other words, amino acids can be considered as derivatives of carboxylic acids, in the molecules of which one or more hydrogen atoms are replaced by amino groups.
Thus, the general formula of amino acids can be written as (NH 2) x R(COOH) y, where x and y are most often equal to one or two.
Since amino acids have both an amino group and a carboxyl group, they exhibit chemical properties similar to both amines and carboxylic acids.
Acidic properties of amino acids
Formation of salts with alkalis and alkali metal carbonates
Esterification of amino acids
Amino acids can enter into an esterification reaction with alcohols:
NH 2 CH 2 COOH + CH 3 OH → NH 2 CH 2 COOCH 3 + H 2 O
Basic properties of amino acids
1. Formation of salts upon interaction with acids
NH 2 CH 2 COOH + HCl → + Cl -
2. Interaction with nitrous acid
NH 2 -CH 2 -COOH + HNO 2 → HO-CH 2 -COOH + N 2 + H 2 O
Note: interaction with nitrous acid proceeds in the same way as with primary amines
3. Alkylation
NH 2 CH 2 COOH + CH 3 I → + I -
4. Interaction of amino acids with each other
Amino acids can react with each other to form peptides - compounds containing in their molecules a peptide bond -C (O) -NH-
At the same time, it should be noted that in the case of a reaction between two different amino acids, without observing some specific synthesis conditions, the formation of different dipeptides occurs simultaneously. So, for example, instead of the reaction of glycine with alanine above, leading to glycylanine, a reaction leading to alanylglycine can occur:
In addition, a glycine molecule does not necessarily react with an alanine molecule. Peptization reactions also take place between glycine molecules:
And alanine:
In addition, since the molecules of the resulting peptides, like the original molecules of amino acids, contain amino groups and carboxyl groups, the peptides themselves can react with amino acids and other peptides due to the formation of new peptide bonds.
Individual amino acids are used to produce synthetic polypeptides or so-called polyamide fibers. So, in particular, using the polycondensation of 6-aminohexanoic (ε-aminocaproic) acid, nylon is synthesized in industry:
The nylon resin obtained as a result of this reaction is used for the production of textile fibers and plastics.
Formation of internal salts of amino acids in aqueous solution
In aqueous solutions, amino acids exist mainly in the form of internal salts - bipolar ions (zwitterions):
Getting amino acids
1) The reaction of chlorinated carboxylic acids with ammonia:
Cl-CH 2 -COOH + 2NH 3 \u003d NH 2 -CH 2 -COOH + NH 4 Cl
2) Breakdown (hydrolysis) of proteins under the action of solutions of strong mineral acids and alkalis.
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 interaction:
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 grounds:
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, becoming ester. Esters of amino acids 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 \u003d NH 2 -CH (R) -CONH 2 + H 2 O
The interaction of amino acids with strong acids:
Getting 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
We list the physical properties of amino acids:
- Colorless
- Have a crystalline form
- Most amino acids taste sweet, but depending on the radical (R) may be bitter or tasteless
- Highly soluble in water, but poorly soluble in many organic solvents
- Amino acids have the property of optical activity
- Melt with decomposition at temperatures above 200°C
- non-volatile
- Aqueous solutions of amino acids in acidic and alkaline media conduct electricity
Amino acids.
Amino acids(aminocarboxylic acids) - organic compounds, the molecule of which simultaneously contains carboxyl (-COOH) and amine groups (-NH2).
The structure of amino acids can be expressed by the following general formula,
(where R- hydrocarbon radical, which may contain various functional groups).
Amino acids can be considered derivative carboxylic acids, in which one or more hydrogen atoms are replaced by amine groups (-NH2).
An example is the simplest: aminoacetic acid, or glycine, and aminopropionic acid or alanine:
Chemical properties of amino acids
Amino acids - amphoteric compounds, i.e. depending on the conditions, they can exhibit both basic and acidic properties.
Due to the carboxyl group ( -COOH) they form salts with bases.
Due to the amino group ( -NH2) form salts with acids.
The hydrogen ion split off during dissociation from the carboxyl ( -HE) amino acid, can pass to its amino group with the formation of an ammonium group ( NH3+).
Thus, amino acids exist and react also in the form of bipolar ions (internal salts).
This explains that solutions of amino acids containing one carboxyl and one amino group have a neutral reaction.
Alpha amino acids
From molecules amino acids protein molecules are built proteins, which, when completely hydrolyzed under the influence of mineral acids, alkalis or enzymes, decompose, forming mixtures of amino acids.
The total number of naturally occurring amino acids reaches 300, but some of them are quite rare.
Among the amino acids, a group of the 20 most important is distinguished. They are found in all proteins and are called alpha amino acids.
Alpha amino acids are crystalline substances that are soluble in water. Many of them have a sweet taste. This property is reflected in the name of the first homologue in the alpha-amino acid series - glycine, which was also the first alpha-amino acid found in a natural material.
Below is a table with a list of alpha amino acids:
Name | Formula | Residue name |
|---|---|---|
| Amino acids with aliphatic radicals | ||
| OH group | ||
| Ser | ||
| Thr | ||
| Amino acids with radicals containing a COOH group | ||
| asp | ||
| Glu | ||
| Amino acids with radicals containing NH2CO-group | ||
| Asn | ||
| Gln | ||
| Amino acids with radicals containing NH2-group | ||
| Lys | ||
| Arg | ||
| Amino acids with radicals containing sulfur | ||
| Cys | ||
| Met | ||
| Amino acids with aromatic radicals | ||
| Phe | ||
| Tyr | ||
| Amino acids with heterocyclic radicals | ||
| trp | ||
| His | ||
| Pro | ||
Essential amino acids
main source alpha amino acids for the animal organism are food proteins.
Many alpha-amino acids are synthesized in the body, while some alpha-amino acids necessary for protein synthesis are not synthesized in the body and must come from outside, with food. These amino acids are called indispensable. Here is their list:
Amino acid name | Name of food |
|---|---|
grains, legumes, meat, mushrooms, dairy products, peanuts |
|
almonds, cashews, chicken meat, chickpeas (chickpeas), eggs, fish, lentils, liver, meat, rye, most seeds, soy |
|
meat, fish, lentils, nuts, most seeds, chicken, eggs, oats, brown (unpeeled) rice |
|
fish, meat, dairy products, wheat, nuts, amaranth |
|
milk, meat, fish, eggs, beans, beans, lentils and soy |
|
dairy products, eggs, nuts, beans |
|
legumes, oats, bananas, dried dates, peanuts, sesame seeds, pine nuts, milk, yogurt, cottage cheese, fish, chicken, turkey, meat |
|
legumes, nuts, beef, chicken meat, fish, eggs, cottage cheese, milk |
|
pumpkin seeds, pork, beef, peanuts, sesame seeds, yogurt, swiss cheese |
|
tuna, salmon, pork tenderloin, beef fillet, chicken breasts, soybeans, peanuts, lentils |
In some, often congenital, diseases, the list of essential acids is expanding. For example, with phenylketonuria, the human body does not synthesize another alpha-amino acid - tyrosine, which in the body of healthy people is obtained by hydroxylation of phenylalanine.
The use of amino acids in medical practice
Alpha amino acids occupy a key position in nitrogen metabolism. Many of them are used in medical practice as medicines affecting tissue metabolism.
So, glutamic acid used to treat diseases of the central nervous system, methionine and histidine– treatment and prevention of liver diseases, cysteine- eye diseases.