Protein biosynthesis on ribosome

Amino acids - (aminocarboxylic acids; AMK) - organic compounds, in the molecule of which is contained at the same timecarboxyl and amine groups (amino group). Those. butminocislots can be considered, as derivatives of carboxylic acids, in which one or more hydrogen atoms are replaced by amino groups.

• Carboxyl group (carboxyl) -son - a functional monovalent group, which is part of carboxylic acids and determining their acidic properties.
• Amino group - Functional chemical monovalent group -NH 2,an organic radical containing one nitrogen atom and two hydrogen atoms.

More than 200 natural amino acids are known.which can be classified differently. Structural classification proceeds from the position of functional groups on alpha, beta, gamma or deltop position of amino acids.

In addition to this classification, there are also other, for example, a polarity classification, pH level, as well as the type of side chain group (aliphatic, acyclic, aromatic amino acids, amino acids containing hydroxyl or sulfur, etc.).

Amino acid proteins are the second (after water) components of the muscles, cells and other tissues of the human body. Amino acids play a crucial role in such processes as transporting neurotransmitters and biosynthesis.

General structure of amino acids. Alpha amino acids. Isomerization of amino acids.

Amino acids - biologically important organic compounds consisting of amino groups (-NH 2) and carboxylic acid (-son), and having a side chain specific to each amino acid. Key elements of amino acids - carbon, hydrogen, oxygen and nitrogen. Other elements are in the lateral chain of certain amino acids.

Fig. 1 is the overall structure of α-amino acids that make up proteins (except for proline). Composite parts of an amino acid molecule - an amino group NH 2, carboxyl group COOH, radical (differ in all α-amino acids), an α-atom of carbon (center).

In the amino acid structure, the side chain, specific for each amino acid, is denoted by the letter R. The carbon atom located near the carboxyl group is called alpha carbon, and amino acids, the side chain of which is associated with this atom, are called alpha-amino acids. They are the most common form of amino acids.

Alpha-amino acids, with the exception of glycine, alpha carbon is a chiral carbon atom. In amino acids, carbon chains of which are joined by alpha carbon (as, for example, lysine (L-lysine)), carbon are designated as alpha, beta, gamma, delta, and so on. In some amino acids, the amino group is attached to beta or gamma carbon, and therefore they are called beta or gamma-amino acids.

According to the properties of the side chains, amino acids are divided into four groups. The side chain can make an amino acid with weak acid, weak base, or emulsoid (if the side chain is polar), or hydrophobic, poorly absorbing water, substance (if the lateral circuit is not polar).

The term "branched chain amino acid" refers to amino acids having aliphatic nonlinear side chains, it is leucine, isoleucine and valine.

Proline - The only proteinogenic amino acid, the side group of which is attached to the alpha-amino group and, thus, is also the only proteinogenic amino acid containing a secondary amine in this position. From a chemical point of view, proline, thus, is an imino acid, since it does not have a primary amino group, although in the current biochemical nomenclature it is still classified as an amino acid, as well as "N-alkylated alpha-amino acid" ( Imino acid - carboxylic acids containing the imino group (NH). Parts are included in the composition of the proteins, their exchange is closely associated with the exchange of amino acids. According to its properties, imino acids are close to amino acids, and as a result of catalytic hydrogenation of imino acids turn into amino acids. IminoGroup - Molecular NH group. Bivalent. Contained in secondaryamina and peptides. In free form, the bivalent radical of ammonia does not exist).

Alfa-amino acids

Amino acidshaving both amine and carboxyl group attached to the first (alpha) carbon atom are of particular importance in biochemistry. They are known as 2-, alpha or alpha-amino acids (general formula in most cases H 2 NCHRCOOH, where R is an organic substituent, known as the "side chain"); Often the term "amino acid" refers to them.

These are 22 proteinogenic (that is, "employees for the construction of a protein") amino acids, which are combined into peptide chains ("polypeptides"), providing a wide range of proteins. They are L-stereoisomers ("left" isomers), although some bacteria and in some antibiotics there are some of the D-amino acids ("right-wing" isomers).

Fig. 2. Peptide bond is the form of an amide bond arising from the formation of proteins and peptides as a result of the interaction of α-amino group (-NH 2) of one amino acid with an α-carboxyl group (-son) of another amino acid.

Of the two amino acids (1) and (2), a dipeptide is formed (a chain of two amino acids) and a water molecule. On the same schemeribosome Generates longer amino acid chains: polypeptides and proteins. Different amino acids that are "building blocks" for a protein, differ in R.

Optical isomeria amino acids

Fig. 3. Optical isomers of Alanine amino acids

Depending on the position of the amino group, relative to the 2nd carbon atom, α-, β-, γ- and other amino acids are isolated. For the organism of mammals, the most characteristic α-amino acids. All incoming α-amino acid organisms exceptglycin, contain asymmetric carbon atom (Thinoninand Isoleucinecontain two asymmetric atoms) and have optical activity. Almost all α-amino acids occurring in nature have a L-configuration, and only L-amino acids are included in proteins synthesized on Ribosomes.

All standard alpha-amino acids other than glycine may exist in the form of one of two enantiomer , called L or D amino acids, which are mirror mappings each other.

D, L-System designation of stereoisomers.

On this system, L-configuration is attributed to the stereosometer, which in the Fisher's projections, the reference group is located to the left of the vertical line (from the lat. "Laevus" -live). We must remember that in fisher's projections At the top there are the most oxidized carbon atom (as a rule, this atom is included in the carboxyl coin or carbonyl CH \u003d about groups.). In addition, in the projection of Fisher, all horizontal connections are directed towards the observer, and the vertical - removed from the observer. Accordingly, if repernaya group located in the Fisher's projection on the right, the stereoisomer has D - configuration (from lat. "Dexter" - right).In α-amino acids referring groups Serve group NH 2.

Enantiomers - Parastereoisomersrepresenting mirror reflections of each other who are not combined in space. The classical illustration of two enantiomers can serve as the right and left palms: they have the same structure, but different spatial orientation.The existence of enantiomeric forms is associated with the presence of a molecule chirality - Properties are not combined in space with its mirror reflection..

Enantiomers are identical in physical properties. They can be divided only when interacting with a chiral medium, for example, light radiation. Enantiomers equally behave in chemical reactions with agral reagents in ahioral medium. However, if the reagent, the catalyst or solvent is chiral, the reactivity of enantiomers, as a rule, differs.Most of the chiral natural compounds (amino acids, monosaccharides) There is 1 enantiomer in the form of 1.The concept of enantiomeria is important in pharmaceuticals, because various enantiomers of drugs have different biological activity.

Protein biosynthesis on ribosome

Standard amino acids

(proteinogenic)

See topic: And The structure of proteinogenic amino acids

In the process of protein biosynthesis, 20 α-amino acids encoded with a genetic code are included in the polypeptide chain (see Fig. 4). In addition to these amino acids, called proteinogenic, or standard, in some proteins there are specific non-standard amino acids arising from standard in the process of post-translation modifications.

Note: Recently, the proteinogenic amino acids sometimes classly include translating selenocysteine \u200b\u200band pyrrolysis. These are the so-called 21st and 22nd amino acids.

Amino acids are structural compounds (monomers), of which proteins consist. They are combined with each other, forming short polymer chains, called the peptides of the long chain, polypeptides or proteins. These polymers are linear and unbranched, each amino acid in the chain joins two neighboring amino acids.

Fig. 5. Ribosome in the process of broadcast (protein synthesis)

The process of constructing a protein is called a broadcast and includes a step-by-step addition of amino acids to a growing protein chain through ribosisms carried out by ribosome. The order in which amino acids is added is read in the genetic code using the MRNA template, which is a copy RNA One of the genes of the body.

Broadcast - protein biosynthesis on ribosome

Fig. 6 S. tia elongation polypeptide.

Twenty-two amino acids are naturally included in the polypeptides and are called proteinogenic, or natural, amino acids. Of these, 20 are encoded using a universal genetic code.

The remaining 2, selenocysteine \u200b\u200band pyrrolysis are included in proteins using a unique synthetic mechanism. Selenicysteine \u200b\u200bis formed when the translated mRNA turns on the SECIS element that causes the UGA codon instead of stop codon. Pyrrolysin is used by some methane arches as part of the enzymes needed for the production of methane. It is encoded with the UAG codon, which in other organisms usually plays the role of stop codon. The UAG codon follows the Pylis sequence.

Fig. 7. The polypeptide chain is the primary structure of the protein.

Proteins have 4 levels of their structural organization: primary, secondary, tertiary and quaternary. The primary structure is the sequence of amino acid residues in the polypeptide chain. The primary structure of the protein, as a rule, is described using single-bore or three-letter designations for amino acid residues. The system structure is a local ordering of the polypeptide chain fragment stabilized by hydrogen bonds. The ratio structure is the spatial structure of the polypeptide chain. Structurally consists of elements of a secondary structure stabilized by various types of interactions, in which hydrophobic interactions play a crucial role. Quaternary structure (or subunit, domain) is the relative arrangement of several polypeptide chains as part of a single protein complex.

Fig. 8. Structural organization of proteins

Non-standard amino acids

(Non-proteinogenic)

In addition to standard amino acids, there are many other amino acids, which are called non-proteinogenic or non-standard. Such amino acids are either not found in proteins (for example, L-carnitine, gamc) are either not carried out directly in isolation using standard cellular mechanisms (for example, oxyprolin and selenomeometonine).

Non-standard amino acids located in proteins are formed by post-translational modification, that is, modification after the transmission during the protein synthesis. These modifications are often necessary for the functioning or regulation of the protein; For example, glutamate carboxylation makes it possible to improve the binding of calcium ions, and the hydroxylation of the proline is important for maintaining the connective tissue. Another example is the formation of a hipuzine into the EIF5A broadcast initiation factor by modifying the lysine residue. Such modifications may also determine the localization of the protein, for example, the addition of long hydrophobic groups can cause a protein binding with a phospholipid membrane.

Some non-standard amino acids are not found in proteins. It is a lanhyonine, 2-aminoisomasilic acid, dehydroalanin and gamma-amine-oil acid. Non-standard amino acids are often found as intermediate metabolic paths for standard amino acids - for example, ornithine and citrullin are found in an ornithine cycle as part of acid catabolism.

A rare exclusion of alpha-amino acid dominance in biology - beta-amino acid beta-alanine (3-aminopropanic acid), which is used for synthesispantothenic acid (vitamin B5), component of coenzyme A in plants and microorganisms. It, in particular, produce proponionic bacteria.

Amino acid functions

Protein and non-protein functions

Many proteinogenic and non-repository amino acids also play an important, non-associated protein, role in the body. For example, in the human brain, glutamate (standard glutamic acid) and gamma-amine oil acid ( GAMK, non-standard gamma-amino acid), are the main exciting and braking neurotransmitters. Hydroxyproline (the main component of the collagen connective tissue) is synthesized from the RIDP; Standard amino acid glycine is used for synthesis porfirinsused in red blood cells. Non-standard carnitine is used for lipid transport.

Because of its biological significance, amino acids play an important role in nutrition and are commonly used in food additives, fertilizers and food technologies. In industry, amino acids are used in the production of drugs, biodegradable plastic and chiral catalysts.

1. Amino acids, proteins and food

On the biological role and the consequences of the deficiency of amino acids in the human body, see information in the tables of indispensable and replaceable amino acids.

When the person is introduced into the body with food, 20 standard amino acids is either used to synthesize proteins and other biomolecules, or oxidized in urea and carbon dioxide as an energy source. The oxidation begins with the removal of the amino group through the transaminase, and then the amino group is turned on in the urea cycle. Another product of transamidation is ketokisloid, which is included in citric acid cycle. Glukugenic amino acids can also be converted into glucose by means of gluconeogenesis.

Of 20 standard amino acids, 8 (valine, isoleucine, leucine, lysine, methionine, threonine, tryptophan and phenylalanine) are called indispensable because the human body cannot synthesize them independently from other compounds in the quantities necessary for normal growth, they can only be obtained from food. However, according to modern ideas, Gistidin and Argininealso are Indispensable amino acids for children. Others can be conventionally indispensable for people of a certain age or people who have any diseases.

Moreover, Cysteine , Taurine, are considered half-generable amino acids in children (although Taurine is technically not an amino acid), because the metabolic pathways that synthesize these amino acids, children are not yet fully developed. The required amounts of amino acids also depend on the age and human health, therefore it is quite difficult to produce general dietary recommendations here.

Proteins

Proteins (proteins, polypeptides) - high molecular weight Organic substancesconsisting of alphaamino acids connected to the chain peptide connections. In living organisms, the amino acid composition of proteins is determined genetic code, with synthesis in most cases 20standard amino acids.

Fig. 9. Proteins are not only food ... types of protein connections.

Each living organism consists of proteins.. Various forms of proteins take part in all processes occurring in living organisms. In the body of a person from proteins, muscles, ligaments, tendons are formed, all organs and glands, hair, nails; Proteins are part of liquids and bones. Enzymes and hormones catalyzing and regulating all processes in the body are also proteins.The deficit of proteins in the body is dangerous to health. Each protein is unique and exists for special purposes.

Proteins -an important part nutrition Animal and man (main sources: meat, bird, fish, milk, nuts, legumes, grains; to a lesser extent: vegetables, fruits, berries and mushrooms), because in their organisms, all the necessary amino acids can not be synthesized and part must come with protein food. In the process of digestion, the enzymes destroy consumed proteins to amino acids, which are used for biosynthesis of the organism's own proteins or subjected to further decay for energy.

It is worth emphasize that modern nutrition science claims that the protein must satisfy the needs of the body in amino acids not only in quantity. These substances should flow into the human body in certain relations among themselves.

The protein synthesis process is in the body constantly. If at least one indispensable amino acid is absent, the formation of proteins is suspended.This can lead to a variety of serious health violations - from digestive disorders to depression and slowdown in children. Of course, this consideration of the issue is very simplified, because The functions of proteins in the cells of living organisms are more diverse than the functions of other biopolymers - polysaccharides and DNA.

Also, besides proteins, a large amount of non-natural nature substances are formed from amino acids (see below) performing special functions. To them, a member of choline (vitamin-like substance that is part of phospholipids and a precursor of the neurotiator of acetylcholine - neurotransmitters are chemicals that transmit nerve impulse from one nervous cell to another. Thus, some amino acids are extremely necessary for normal brain operation) .

2. Netherless functions of amino acids

Neurotransmitter amino acid

Note: Neuromediators (neurotransmitters, intermediaries) - biologically active chemicals by which the transmission of an electrochemical pulse from the nervous cell through the synaptic space between neurons, as well as, for example, from neurons to muscle tissue or iron cells. For information from its own tissues and organs, the human body synthesizes special chemicals - neurotransmitters.All internal fabrics and human body organs, "subordinate" vegetative nervous system (VNS) are equipped with nerves (innervated), i.e., nerve cells are controlled by the function of the organism. They as sensors collect information about the state of the body and transmit it to the corresponding centers, and the corrective effects go to the periphery. Any violation of vegetative regulation leads to failures in the work of the internal organs. Transmission of information, or control, is carried out using special intermediary chemicals, which are called mediators (from lat. Mediator - intermediary) or neuromediators. By its chemical nature, mediators relate to various groups: biogenic amines, amino acids, neuropeptides, etc. Currently, more than 50 compounds related to mediators have been studied.

In the human body, many amino acids are used to synthesize other molecules, for example:

• Tripotofan is the predecessor of the neurotransmitter of serotonin.

• L-Tyrosine and its predecessor phenylalanine are predecessors of neurotransmitters of dopamine catecholamines, adrenaline and norepinephrine.
  

• Glycine is a predecessor of porphyrins, such as gem.
  

• Arginine is the predecessor of nitrogen oxide.
  

• Ornithine and S-adenosylmethionine are precursors of polyamines.
  

• Aspartate, glycine and glutamine are predecessors of nucleotides.
  

Nevertheless, not all the functions of other numerous are still known. non-standard amino acids. Some non-standard amino acids are used by plants to protect against herbivores. For example, a canvarian is an analogue of arginine, which is contained in many legumes, and in particularly large quantities in Canavalia Gladiata (Meso-shaped Canvalia). This amino acid protects plants from predators, such as insects, and when using some untreated legumes can cause diseases in humans.

Classification of proteinogenic amino acids

Consider the classification on the example of 20 proteinogenic α-amino acids required for protein synthesis

Among the variety of amino acids only 20 participates in the intracellular synthesis of proteins (proteinogenic amino acids). Also in the human body, about 40 non-resistant amino acids were discovered.All proteinogenic amino acids are α-amino acids. In their example, you can show additional ways to classify. The names of amino acids are usually reduced to 3 letter notation (see Fig. Polypeptide Chain Top Page). Professionals in molecular biology also use single-score characters for each amino acid.

1. on the structure of the lateral radicalallocate:

• aliphatic (alanine, valine, leucine, isoleucine, proline, glycine) - compounds that do not contain aromatic ties.
  
• aromatic (phenylalanine, tyrosine, tryptophan)

• sellowering (cysteine, methionine) containing sulfur atom
  
• containing He-group (serine, threonine, again tyrosine),
• containing additional Soam group (asparagic and glutamic acid),
• additional NH 2 -Group (Lizin, Arginine, Gistidin, also glutamine, asparagin).

2. According to the polarity of the side radical

There are non-polar amino acids (aromatic, aliphatic) and polar (uncharged, negative and positively charged).

3. According to acidic properties

The acidic properties are subdivided by neutral (most), acidic (aspartic and glutamine acids) and basic (lysine, arginine, histidine) amino acids.

4. By indispensability

If necessary, it is allocated for the body that are not synthesized in the body and should flow with food - essential amino acids (leucine, isoleucine, valine, phenylalanine, tryptophan, threonine, lysine, methionine). Replaced includes such amino acids, the carbon skeleton of which is formed in the metabolic reactions and is capable of obtaining an amino group to form an amino acid. Two amino acids are conditionally indispensable (arginine, histidine), i.e. and synthesis occurs in insufficient quantities, especially for children.

Table 1. Classification of amino acids

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

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

Amino acid properties

The amino group - NH 2 defines the basic properties of amino acids, since it is able to attach a hydrogen cation by a donor-acceptor mechanism due to the presence of a free electron pair at a nitrogen atom.

Group -Oson (carboxyl group) determines the acidic properties of these compounds. Consequently, amino acids are amphoteric organic compounds. With alkalis, they react as acids:

With strong acids, as the base-amines:

In addition, the amino group in amino acid enters into interaction with the carboxyl group included in its composition, forming an internal salt:

Ionization of amino acid molecules depends on the acid or alkaline nature of the environment:

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

Amino acids are colorless crystalline substances that melted with decomposition at temperatures above 200 ° C. They are soluble in water and insoluble on the air. 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-forms. Approximately half of these amino acids belong to indispensable, so on. They are not synthesized in the human body. Indispensable are acids such as valine, leucine, isoleucine, phenylalanine, lysine, threonine, cysteine, methionine, histidine, tryptophan. In the human body, these substances come with food. If their quantity in food is insufficient, the normal development and functioning of the human body is violated. In case of individual diseases, the organism is not able to synthesize some other amino acids. So, with 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 amide group -NH-CO-, for example:

High molecular weight compounds obtained as a result of such a reaction contain a large number of amide fragments and therefore got a name polymamides.

In addition to the above-mentioned synthetic fiber of Capron, for example, and annta formed during polycondensation of aminoeantic acid is believed. To obtain synthetic fibers, amino acids are suitable with the arrangement of amino and carboxyl groups at the ends of the molecules.

Alpha-amino acid polyamides are called peptides. Depending on the number of residues, amino acids distinguish dippeptides, Tripeptides, Polypeptides. In such compounds, the group -NH is called peptide.

Isomerius and amino acid nomenclature

The amino acid isomeria is determined by the various structure of the carbon chain and the position of the amino group, for example:

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

Methods for producing amino acids

Amino acids - the main building material of any living organism. By their nature, they are primary nitrogenous substances of plants, which are synthesized from the soil. The structure and amino acids depend on their composition.

Amino acid structure

Each of its molecule has carboxyl and amine groups that are connected to a radical. If the amino acid contains 1 carboxyl and 1 amino group, the structure can be designated by the formula shown below.

Amino acids that have 1 acid and 1 alkaline group are called monoamino-corbon. The organisms are also synthesized and the functions of which determine 2 carboxyl groups or 2 amine groups. Amino acids containing 2 carboxyl and 1 amine groups are called monoaminodicarbonic, and having 2 amine and 1 carboxyl - diaminonocarbonic.

They are also different in the structure of an organic radical R. each of them has its own name and structure. From here and various functions of amino acids. It is the presence of acid and alkaline groups that provides its high reactivity. These groups combine amino acids and form a polymer - protein. Proteins are still referred to as the polypeptides due to its structure.

Amino acids as building material

The protein molecule is a chain of dozens or hundreds of amino acids. Proteins differ in composition, quantity and order of amino acid arrangement, because the number of combinations of 20 components is almost infinite. Some of them have the whole composition of essential amino acids, others cost 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, since small-soluble and not split the gastrointestinal tract. This belongs to the proteins of nails, hair, wool or feathers.

The functions of amino acids are difficult to overestimate. These substances are the main food in the diet of people. What function do amino acids perform? They increase the growth of muscle mass, help the strengthening of joints and ligaments, restore damaged organism tissues and participate in all processes occurring in the human body.

Indispensable amino acids

Only from additives or food products you can get functions in the process of forming healthy joints, strong muscles, beautiful hair is very significant. These amino acids include:

• phenylalanine;
• lysine;
• threonine;
• methionine;
• valin;
• leucine;
• tryptophan;
• histidine;
• isoleucine.

Functions of amino acids are essential

These bricks perform essential functions in the work of each cell of the human body. They are invisible, while entering the body in sufficient quantities, but their lack significantly worsens the work of the whole body.

1. Valin renews the muscles, serves as an excellent source of energy.
2. Gistidine improves blood composition, contributes to the restoration and growth of muscles, improves the work of the joints.
3. Isoleucine helps hemoglobin production. Controls the amount of blood sugar, increases human energy, stamina.
4. Leucin strengthens immunity, monitors the level of sugar and leukocytes in the blood. If the level of leukocytes is overestimated: it lowers them and connects the reserves of the body to eliminate inflammation.
5. Lizin helps the absorption of calcium, which forms and strengthens the bone. Helps collagen generation, improves hair structure. For men, this is an excellent anabolic, as it is increasing the muscles and increases male strength.
6. Metionine normalizes the work of the digestive system and the liver. Participates in the splitting of fats, removes toxicosis in pregnant women, has a beneficial effect on the hair.
7. Threonine improves the work of the gastrointestinal tract. Enhances immunity, participates in the creation of elastin and collagen. Thronin prevents the deposition of fat in the liver.
8. Tiptophan is responsible for human emotions. Serotonin generates a hormone of happiness, thereby normalizes sleep, raises the mood. Takes up appetite, charitable affects the heart muscle and artery.
9. Phenylalanine serves as a transmitter of signals from nerve cells into the brain of the head. Improves mood, suppresses an unhealthy appetite, improves memory, increases susceptibility, reduces pain.

The shortage of essential amino acids leads to a stop of growth, disruption of metabolism, a decrease in muscle mass.

Replaceable amino acids

These are such amino acids, the structure and functions of which are produced in the body:

• arginine;
• alanine;
• asparagin;
• glycine;
• proline;
• taurine;
• tyrosine;
• glutamate;
• serine;
• glutamine;
• ornithine;
• cysteine;
• carnitine.

Functions amino acids are replaceable

1. Cysteine \u200b\u200beliminates toxic substances, participates in the creation of skin tissues and muscles, is a natural antioxidant.
2. Tyrosine reduces physical fatigue, accelerates metabolism, eliminates stress and depression.
3. Alanine serves to grow muscles, is a source of energy.
4. Increases metabolism and reduces ammonia formation at large loads.
5. Cystin eliminates pain when injury to ligaments and joints.
6. Responsible for cerebral activity, during long physical exertion goes into glucose, producing energy.
7. The glutamine restores the muscles, increases immunity, speeds up the metabolism, increases the work of the brain and creates a growth hormone.
8. Glycine is necessary for muscle operation, fat cleavage, stabilization of blood pressure and blood sugar.
9. Carnitine moves fatty acids into the cells where their splitting is performed with energy is performed, as a result of which excess fat is burned and energy is generated.
10. Ornithine produces growth hormone, participates in the process of urica, breaks fatty acids, helps insulin production.
11. Proline provides collagen production, it is necessary for ligaments and joints.
12. Serin increases immunity and produces energy, needed for rapid metabolism of fatty acids and muscle growth.
13. Taurine breaks fat, raises the resistance of the body, synthesizes bile salts.

Protein and its properties

Proteins, or proteins - high molecular compounds with nitrogen content. The concept of "protein", first designated by Britter in 1838, comes from the Greek word and means "primary", which displays the leading value of proteins in nature. The variety of proteins makes it possible for the existence of a huge number of living beings: from bacteria to the human body. They are significantly more than other macromolecules, because proteins are the foundation of a living cell. Approximately 20% of the masses of the human body, more than 50% of the dry mass of the cell. Such a number of diverse proteins is due to the properties of twenty different amino acids, which interact with each other and create polymer molecules.

The outstanding property of proteins is the ability to independently create a specific spatial structure characteristic of a specific protein. Proteins are biopolymers with peptide bonds. For the chemical composition of proteins, the constant average of nitrogen content is 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 can not be replaced by other elements, their role in the human body is extremely important.

Protekov functions

The need for proteins is functions:

• it is necessary for growth and development, as it acts as the main building material for creating new cells;
• manages metabolism during which energy is released. After taking food, the metabolic rate increases, for example, if the food consists of carbohydrates, metabolism is accelerated by 4%, if 30% from proteins;
• regulated in the body, due to its hydrophilicity - the ability to attract water;
• enhance the work of the immune system, synthesizing antibodies that protect against infection and eliminate the threat of the disease.

Products - sources of proteins

Muscles and skeleton of a person consist of living fabrics that are not only functioning throughout life, but also updated. Restored after damage, keep their strength and strength. For this they require well-defined nutrients. Food provides the body with the energy required for all processes, including the work of the muscles, growth and restoration of tissues. A protein in the body is used both as a source of energy, and as a building material.

Therefore, it is very important to comply with its daily use in food. Squirt products: chicken, turkey, lean ham, pork, beef, fish, shrimp, beans, lentils, bacon, eggs, nut. All these products provide a protein organism and give the energy necessary for life.

Amino acids whose formulas are discussed in the course of chemistry of high school, are important substances for the human body. Proteins consisting of amino acid residues are necessary for a person for full-fledged life.

Definition

Amino acids whose formulas will be discussed below are organic compounds in which the molecules of which contain amino and carboxyl groups. Carboxyl consists of carbonyl and hydroxyl grouping.

Amino acids can be considered as derivatives of carboxylic acids, where the hydrogen atom is substituted on the amino group.

Features of chemical properties

Amino acids whose general formulas can be represented as CNH2NNH2COOH are amphoteric chemical compounds.

The presence of two functional groups in their molecules explains the possibility of the manifestation of these organic substances of the main and acidic properties.

Their aqueous solutions have the properties of buffer solutions. Zwitter-ion - amino acids, where the amino group has the form of NH3 +, and carboxyl is presented as -COO-. The molecule of this species has an essential dipole moment, while the total charge is zero. At such molecules, crystals of many amino acids are built.

Among the most important chemical properties of this class of substances, polycondensation processes can be distinguished, as a result of which polyamides are formed, including proteins, peptides, nylon.

Amino acids, the total formula of which has the form of CNH2NNH2COOH, react with acids, bases, oxides of metals, weak acid salts. Of particular interest are the interactions of amino acids with alcohols related to esterification.

Features of isomeria

In order to write the structural formulas of amino acids, we note that many amino acids participating in biochemical transformations contain an amino group in the A-position from the carboxyl group. Such a carbon atom is A amino acids consider optical isomers.

The structural formula of amino acids gives an idea of \u200b\u200bthe location of the main functional groups that are part of this substance relative to the active carbon atom.

Natural amino acids that are part of protein molecules are representatives of L-series.

For optical isomers of amino acids, spontaneous slow non-enzymatic racemia is characteristic.

Features A-connections

Any formula of substances of this species involves the arrangement of the amino group in the second carbon atom. The formulas are considered even in the school course of biology, also belong to this type. For example, they include alanine, asparagin, serine, leucine, tyrosine, phenylalanine, valine. It is these compounds that make up the genetic code of a person. In addition to standard connections? Also in protein molecules, non-standard amino acids are detected, which are their derivatives.

Synthesis classification

How can I divide the indispensable amino acids? The formulas of this class are divided into physiological attribute to the semi-generable, capable of synthesize in the human body. Ordinary compounds synthesized in any living organism are isolated.

Division of radical and functional groups

The formula of amino acids differs in the structure of the radical (lateral group). There is division into non-polar molecules containing a hydrophobic non-polar radical, as well as charged polar groups. As a separate group in biochemistry, histidine, tryptophan, tyrosine are considered. Depending on the functional groups, several groups are distinguished. Aliphatic compounds are presented:

• monoaminocarbonic compounds, which can be considered glycine, valine, alanine, leucine;
• oxymonicamicarboxylic substances: threonine, serine;
• monoaminocarbonic: glutamic, aspartic acid;
• sulfur compounds: methionine, cysteine;
• diaminonocarbon substances: lysine, histidine, arginine;
• heterocyclic: proline, histidine, Truitofan /

Any formula of amino acids can be recorded in general form, only radical groups will differ.

Qualitative definition

In order to detect minor amounts of amino acids, it is carried out in the process of heating amino acids with an overpressure of ningidrin, a purple product is obtained if the acid has a free A-amino group, and for the protected group, it is characterized by obtaining a yellow product. This technique has a high sensitivity, applied to colorimetric identification of amino acids. On its basis, the method of distribution chromatography on paper embedded by Martin in 1944 was created.

The same chemical reaction is used in an automatic amino acid analyzer. The device created by Murom, the spacma, stein is based on the separation of the amino acid mixture in the columns, which are filled out of the column flows the eluent current into the mixer, ningidrin goes here.

The intensity of the resulting color is judged on the quantitative content of amino acids. The testimony fixes the photoelectrocolorimeter, registers the recorder.

Such technology is currently used in clinical practice when conducting blood tests, spinal fluid, urine. It allows you to give a complete picture of the qualitative composition of amino acids contained in biological fluids, determine non-standard nitrogen-containing substances in them.

Features Nomenclature

How to correctly call amino acids? The formulas and names of these compounds are given on the international nomenclature of the Jew. The amino group is added to the appropriate carboxylic acid, starting the numbering from the hydrocarbon facing under the carboxyl group.

For example, 2-aminoethanic acid. In addition to the international nomenclature, there are trivial names that enjoy in biochemistry. So, aminoacetic acid is glycine used in modern medicine.
In the presence of two carboxyl groups in the molecule, suffix is \u200b\u200badded in the title. For example, 2-aminobutandionic acid.

For all representatives of this class, structural isomerism is characterized by changes in the structure of the carbon chain, as well as the location of carboxyl and amino groups. In addition to Glycine (the simplest representative of this class of oxygen-containing organic substances)? The remaining compounds have mirror antipodes (optical isomers).

Application

Amino acids are common in nature, they are the basis for building animals and vegetable proteins. These compounds are used in medicine in the event of strong exhaustion of the body, for example, after complex surgical operations. Glutamic acid helps to fight nerve diseases, histidine is used for the treatment of stomach ulcers. In the synthesis of synthetic fibers (Capron, Enanta), an aminocapronic and aminoenalic acid appears as the feedstock.

Conclusion

Amino acids are organic compounds that have two functional groups in their composition. It is the features of the structure that explain the duality of their chemical properties, as well as the specifics of their use. According to the results of research experiments, it was possible to establish that biomass of living organisms that live on our planet, in the amount of 1.8 × 1012-2.4 · 1012 tons of dry matter. Amino acids are the initial monomers in the biosynthesis of protein molecules, without which the existence of man and animals is impossible.

Depending on the physiological signs, there is a division of all amino acids to essential substances, the synthesis of which is not carried out in the human body and mammals. In order not to have no violations in metabolic processes, it is important to use food products in which these amino acids have.

It is these compounds that are peculiar "bricks", which are used to build protein biopolymers. Depending on which amino acid residues, in which sequence will be built into the structure of the protein, the produced protein has certain physical and chemical properties and applications. Due to the high-quality reactions to the functional groups of biochemists, the composition of protein molecules is determined, they are looking for new paths for the synthesis of individual biopolymers necessary for the human body.

Amino acids - compounds that contain in the molecule at the same time amino group and carboxyl group. The simplest representative of amino acids is an aminoacetic (glycine) acid: NH 2 -CH 2 -COOH

Since amino acids contain two functional groups, then their properties depend on these groups of atoms: NH 2 - and -Con. Amino acids - amphoteric organic substances reacting as a base and as an acid.

Physical properties.

Amino acids are colorless crystalline substances that are well soluble in water and poorly soluble in organic solvents. Many amino acids have a sweet taste.

Chemical properties

Acids (basic properties manifest)

Basis

Amino acids - the formation of peptides

Amino acids do not change the color of the indicator if the number of amino groups and carboxyl groups is equally.

1) NH 2 -CH 2 -COOH + NCL → NH 3 CH 2 -COOH

2) NH 2 -CH 2 -COOH + NaOH → NH 2 -CH 2 -Coona + H 2 O

3) NH 2 -CH 2 -COOH + NH 2 -CH 2 -COOH → NH 2 -CH 2 -CO NH-CH 2 -COOH + H 2 O

The biological role of amino acids lies in the fact that the primary structure of the protein is formed from their residues. There are 20 amino acids that are source substances for protein production in our body. Some amino acids are used as therapeutic agents, such as glutamic acid - with nervous diseases, histidine - with a stomach ulcer. Some amino acids are used in the food industry, they are added to canned food and food concentrates to improve food.

Ticket number 16.

Anilin is a representative of amines. Chemical structure and properties, receipt and practical application.

Amines are organic compounds, which are derived ammonia, in the molecule of which one, two or three hydrogen atoms are substituted for a hydrocarbon radical.

General formula:

Physical properties.

Aniline is a colorless oily liquid with a weak characteristic odor, alive in water, but well soluble in alcohol, ether, benzene. Boiling point 184 ° C. Aniline - strong poison, acts on blood.

Chemical properties.

Acids (amino reactions)

BR 2 (aqueous solution)

C 6 H 5 NN 2 + NCl → C 6 H 5 NN 3 Cl

The chemical properties of aniline are due to the presence in its molecule amino group -NH 2 and the benzene nucleus that have a mutual influence on each other.

Getting.

Restoration of nitro compounds - Zinin Reaction

C 6 H 5 NO 2 + H 2 → C 6 H 5 NN 2 + H 2 O

Application.

Aniline is used in the production of photographic materials, aniline dyes. Polymers, explosives, drugs are obtained.

Ticket number 17.

Proteins - like biopolymers. The structure, properties and biological functions of proteins.

Proteins (proteins, polypeptides.) - High molecular weight organic substances consisting of amino acid peptide bonds connected into a chain. In living organisms, the amino acid composition of proteins is determined by the genetic code, in most cases 20 standard amino acids are used in the synthesis.

Structure of protein

Protein molecules are linear polymers consisting of α-amino acids (which are monomers) and, in some cases, from modified major amino acids. The sequence of amino acids in protein corresponds to the information contained in the gene of this protein.

· Primary structure is a sequence of amino acids in a polypeptide chain-linear.

· Secondary structure - twisting of the polypeptide chain into a spiral supported by hydrogen bonds.

· Tertiary structure -Pacing of the secondary spiral in the ball. Support the tertiary structure: disulfide bonds, hydrogen bonds.

Properties

Proteins are amphoteric substances, as well as amino acids.

They differ in the degree of solubility in water, but most proteins dissolve in it.

Denaturation: a sharp change in conditions, for example, heating or processing of protein by acid or pitch leads to the loss of quaternary, tertiary and secondary protein structures. Denaturation in some cases reversible.

Hydrolysis: Under the influence of enzymes, protein hydrole occurs to the amino acids components. This process occurs, for example, in the stomach of a person under the influence of enzymes such as pepsin and trypsin.

Protein features in the body

Catalytic function

Enzymes - a group of proteins with specific catalytic properties. Among enzymes can be noted such proteins: trypsin, pepsin, amylase, lipase.

Structural function

Proteins are a building material of almost all tissues: muscle, support, coating.

Protective function

Antibody proteins capable of neutralizing viruses, pathogenic bacteria .

Signal function

Proteins receptors perceive and transmit signals received from neighboring cells.

Transport function

Hemoglobin transfers oxygen from the lungs to the rest of the tissues and carbon dioxide from the tissues to the slight.

Floor function

Such proteins include the so-called backup proteins that are poisoned as an energy source and substances in plant seeds and animal eggs. They serve as a building material.

Motor function

Proteins that carry out contractual activity is Aktin and Miosin

Ticket number 17.

1. General characteristics of high molecular compounds: composition, structure, reactions underlying their preparation (on the example of polyethylene).

High molecular weight compounds (polymers) - These are substances whose macromolecules consist of many times repetitive links. Their relative molecular weight can be measured from several thousand to many millions.

Monomer - This is a low molecular weight substance from which the polymer is obtained.

Structural link - multiply repeated in the macromolecule of the polymer group of atoms.

Polymerization degree - the number of repeated structural links.

nSN 2 \u003d CH 2 → (-CH 2 -CH 2 -) n

Polymers can be obtained as a result of polymerization and polycondensation reactions.

Signs of reaction polymerization:

1. No side substances are formed.

2. The reaction is due to double or triple connections.

nSN 2 \u003d CH 2 → (-CH 2 -CH 2 -) N- The reaction of the polymerization of ethylene is the formation of polyethylene.

Signs of reaction polycondensation:

1. Side substances are formed.

2. The reaction is due to functional groups.

Example: The formation of phenol formaldehyde resin from phenol and formaldehyde, polypeptide communication from amino acids. In this case, in addition to the polymer, the by-product is water.

High molecular weight compounds have certain advantages over other materials: they are resistant to the action of reagents, do not conduct a current, mechanical durable, lungs. Based on polymers, films, varnishes, rubber, plastics are obtained.