The human body is a very complex structure that consists of a large number of cells. Each such cell contains a special type of protein. It is the building material of our body, and also performs other vital functions. This protein is called a “peptide”.

Peptides are a type of chemical compound that contains amino acid residues in their molecules.

The number of monomeric amino acid units in one such molecule reaches several dozen. Amino acids are connected to each other through “peptide” bonds. This is what gave the substances their name.

a brief description of

Peptides are the smallest elements of protein molecules. As a rule, they are formed from 2-3 amino acids. There are also oligopeptides. They contain up to two dozen amino acids. After the number of links increases to fifty, the protein itself is formed.

Not only the human body, but also the organisms of other living beings consists of protein. More than a hundred years ago, scientists described a method that makes it possible to synthesize proteins in the laboratory. This process occurs thanks to living cells of humans, representatives of flora and fauna.

The characteristic properties of peptides and their effects on the human body depend on the following factors:

• number of amino acid units;
• sequences of compounds of amino acid residues;
• secondary structure of peptides.

Today, more than 1,500 varieties of these substances are known. Their effect on the human body has been studied at the proper level.

Peptide classification

According to the functions performed, they are divided into several types:

• hormonal - this group includes prolactin and somatotropin. Produced by the pituitary gland and hypothalamus. Take part in the process of cellular regeneration;
• neuropeptides - produced in the central and peripheral nervous systems. Thanks to them, the basic physiological processes of the body are carried out;

• immunological – perform a protective function: prevent toxic effects on the human body;
• bioregulators – control biological processes and regulate physiological activity.

In turn, bioregulators are divided into several types:

• regulate the production of hormones;
• regulate the digestion process and appetite;
• have analgesic properties;
• regulate vascular tone and blood pressure levels.

There is another classification - according to the size of the molecules:

• oligopeptides (contain up to 20 amino acid residues);
• polypeptides (contain more than 20 amino acid residues). This characteristic makes it possible to classify polypeptides as complete proteins.

Impact on the human body

The mechanism of the effect of peptides on the body is quite well studied. Scientists were able to prove that they are able to regulate the vital processes of cells. It is also known that the rate of aging of the body directly depends on the level of peptides in it.

The functions they perform:

• stimulate the process of hormone production, which enhances anabolism processes and is responsible for muscle growth;
• eliminate inflammatory reactions;
• accelerate the healing process of scratches and other skin damage;
• regulate appetite;
• improve skin condition by stimulating the production of elastin and collagen;

• regulate the process of cholesterol production;
• strengthen bones and ligaments;
• strengthen the immune system;
• normalize sleep;
• restore metabolic processes;
• support the regeneration process;
• have antioxidant properties.

What are peptides

Peptides and sports

Analyzing the benefits of amino acid chains for the body, we can conclude that they are very important for athletes. Previously, steroid drugs were used. But now they are prohibited and doping control will not allow an athlete to compete if there is even the slightest suspicion of using these medications.

Proteins and peptides are of great importance for a person involved in sports:

• stimulate the process of synthesizing natural hormones (for example, testosterone);
• promote rapid muscle recovery;
• effectively eliminate disruptions in the body at the local level.

The last point needs to be discussed in more detail. It is a well-known fact that drugs containing hormones have a detrimental effect on human health. And peptides, in turn, have a positive effect on the body. They direct their energy to a specific organ. This process is selective.

Another advantage of peptides is their relatively low price. They are not prohibited by law and are freely available. You should also pay attention to the fact that peptides do not leave traces in the body after their use. This allows you not to worry about possible problems before testing for doping.

If we talk about bodybuilding, here peptides play the following role:

• control appetite levels;
• improve sleep quality;
• bring emotions back to normal;
• increase libido;
• strengthen the immune defenses.

We can say that peptides are very important for a person who plays sports. They help improve physical fitness, but do not harm the body, as other drugs do.

Peptides and cosmetology

In order to heal and rejuvenate the skin, some types of protein began to be added to cosmetics:

• keratin;
• collagen;
• elastin.

Recently, peptides can also be found in caring cosmetics. This innovation appeared in cosmetology about 30 years ago.

Regulatory peptides have a direct effect on the ratio of the number of cells at different stages of their maturation. These chains of amino acids penetrate into the center of the nucleus. They simultaneously “monitor” and regulate important stages in the genetic program:

• control the rate at which stem cells divide;
• deliver an informative DNA base that regulates the process of cell maturation;
• support the required number of receptors and enzymes at the cellular level.

Customer reviews of cosmetics with peptides indicate that it reduces the number of wrinkles, tightens and moisturizes the skin, and makes it brighter.

Such creams heal the skin from the inside, activate its protective functions, which stops the aging process. Increases skin tone. Facial features become clearer.

Fat burning

Today, peptides are used not only in sports, but also for passive weight loss. They act as activity stimulants, which promotes effective fat burning and removal of excess fluid.

Peptides are natural dietary supplements and can be purchased at pharmacies or sports nutrition stores. But before you decide to take such a step, you need to consult a doctor.

For fat burning, the most effective will be. They control appetite, in particular, regulate the amount of sweets consumed.

The peptide reduces the amount of hunger hormone. The group of fat-burning peptides also includes ipamoneril, which slows down the aging process of the body, improves sleep and lifts mood.

If you combine fat burning and active training, then you should pay attention to HGHFrag 176–191. Experienced athletes say that it is excellent for building muscle mass and speeds up the process of muscle recovery after training.

The main advantage of this method of losing weight is that the lost kilograms do not come back. Peptides do this much more effectively than any diet.

What foods contain peptides?

A person can remain healthy only if his cells perform their functions properly. To do this, you need to monitor the level of necessary substances and replenish their reserves.

If there is a lack of peptides synthesized in the body, they can be replenished with the help of medications and food. Scientists have proven that regular consumption of foods high in peptides prolongs life by 30%. But only if you completely give up bad habits and see a healthy lifestyle.

Products that contain large amounts of peptides:

• milk and fermented milk products;
• cereals and legumes;
• fish and seafood (tuna and sardines);
• sunflower seeds and soybeans;

• chicken meat and eggs;
• greenery;
• radish.

There are no contraindications to eating such food. It will be especially useful for older people. It is necessary to monitor the body's reaction after a new product is introduced into the diet.

Side effect

There are cases when peptides have a slight negative effect on the human body. The main signs may be:

• manifestation of autoimmune diseases;
• retention of excess fluid in the body;
• slight increase in blood pressure;

• weakness;
• loss of sensitivity of somatic cells;
• the occurrence of tunnel syndrome.

But these signs are quite minor and do not require long-term treatment. They pass within 3–7 days.

For greater effectiveness, vitamins, supporting antioxidants and extracts can be used in combination with peptides. When used correctly, peptides can save a person from obesity and reduce the risk of pathologies of the cardiovascular system and diabetes.

Video: Peptides in sports

According to the peptide theory, the polypeptide chain is recognized as the basis of the structure of a protein molecule. This chain is built from several tens and sometimes hundreds of amino acid residues linked by peptide bonds.

Proof. Synthesis of polypeptides.

Squirrels– high-molecular nitrogen-containing substances found in cells, mainly in a colloidal state, that is, in a state characterized by extreme instability, the composition of which depends on the properties of the medium.

Mrprotein depends on the number of amino acids in the molecule.

Proteins are monomolecular compounds.

Cytochrome C – 104 amino acid residues, Mr constant.

Linking amino acids to each other

The first assumption about the structure of proteins in 1888 by Danilevsky with alkaline solutions of CuSO 4, all proteins give a blue-violet color. A similar reaction is given by peptones - a product of the breakdown of proteins by protolytic enzymes, a similar reaction is given by biuret:, malonic acid diamide: There are similar connections: C=O;N-H

In proteins, an amide bond, which is formed due to the interaction of the carboxyl group of the 1st amino acid and the amino group of another amino acid

and the proteins themselves are polypeptides

All efforts come down to: protecting the amino group and activating the carboxyl group so that what is needed reacts:

This is Fischer polypeptide synthesis

2. Method of Bergman, Sievers, Curtius.

Zerwes protection: benzyl ester of Cl - carbonic acid is used to protect amino groups.

Curtius activation:

It is necessary to remove the protection from the 1st amino acid.

The boundary between polypeptides and proteins is drawn arbitrarily. Proteins include polypeptides with a molecular weight of 6 thousand or more and a number of amino acid residues over 50. This division principle is based on the ability to dialyze through natural membranes.

A protein molecule can consist of one or more polypeptide chains. The chains can be connected to each other by covalent or non-covalent bonds. Proteins consisting of two or more polypeptide chains that are not interconnected by covalent bonds are called oligomeric. The individual polypeptide chains in such proteins are called protomers; functionally active parts of the protein - subunits.

2Hemoglobin

HEMOGLOBIN - main. squirrels breathe. cycle, involved in the transfer of O2 from the respiratory organs to the tissues, and in the opposite direction - CO2. Contained in red blood cells. In the human body there are 5-6 liters of blood, where ½ ~1/3 are red blood cells, suspended in the blood plasma, which carries daily

Formed from reticulocytes.

Hemoglobin is a complex protein. The protein part is globin, the non-protein part is heme.

Globin consists of 4 pairwise identical polypeptide chains (α-2, β-2). One chain of 146β amino acid residues, the other of 141α.

Gemm – an aromatic flat structure containing Fe, which is connected by 6 coordination bonds on one side with globin, on the other with the nitrogen atoms of the heme pyrrial rings, 1 with the nitrogen atom of histidine, 1 with an oxygen molecule.

Oxyhemoglobin = hemoglobin + O2. Coordination bond with oxygen, iron valency does not change (II). Unstable. This connection is formed as a result of an increase in the partial pressure of oxygen in the lungs. In this case, the tertiary structure of globin changes. It becomes comfortable to hold

Hemoglobin – carrier of protons and carbon dioxide. The binding of O2 to hemoglobin is affected by the pH of the environment and the concentration of CO2. The addition of CO 2 and H + to Hb reduces its ability to bind O2. In peripheral tissues with a decrease in pH and an increase in CO 2 concentration, the affinity of Hb for O 2 decreases as CO 2 and protons bind. CO 2 is released in the pulmonary capillaries and the pH of the environment in the blood increases, therefore the affinity of Hb for O 2 increases (Bohr effect).

Protons are added to histidine radicals at position 146 of the β chain and to other histidines in the α chain. CO 2 attaches to the α-amino ring group of each polypeptide chain. Hb can bind small molecules CN and CO. It binds with carbon monoxide (II) more easily than with oxygen and carboxyhemoglobin is formed. Under the influence of some poisonous oxidizing agents (translation Fe 2+ →Fe 3+), oxidation of Hb into methemoglobin occurs. The color of the blood changes to brown, it does not tolerate O2, when it increases, shortness of breath, mild fatigue, severe headache, vomiting, loss of consciousness are observed, the liver becomes enlarged, and a gray-blue coloration of the mucous membranes and skin. Oxidizing agents: nitro compounds, org. nitro compound, amino compound (aniline, aminophenols, aminohydrosine and their derivatives: polish, paints), chlorates, naphthalene, phenones. Redox paints: methylene, blue.

Treatment . Introduction of antidotes - reducing agents: glucose, sulhydryl compounds. (β – mercaptoethylalanine, oxygen compression (oxygen cushion)).

This may be a hereditary condition. Occurs if in one of the α chains of globin there is tyrosine instead of histidine at position 58. Tyrosine promotes the formation of a covalent bond instead of a coordinate one and the oxidation state of Fe 3+ is fixed

Humans have ~150 types of mutant hemoglobins. The anomaly occurs in 1 in 10,000 people.

Sickle cell anemia. This is a hereditary disease, under the influence of physical activity shortness of breath, taxicardia, ... occurs in the heart. The content of Hb in the blood decreases. Associated diseases arise (kidneys, heart, liver). Red blood cells in the shape of sickles. They become brittle and quickly fail, clogging capillaries. Passed on to children. If only 1 of the parents is sick, the child is a carrier (1%), and if homozygous, then 50% of the red blood cells. Among Africans, 20% are carriers.

The endemic disease of Africans is malaria, only round ones are convenient for the virus => the main population died out. 8% of the black population are carriers of the gene. In the β-chain at position 6, instead of glutamic acid (polar group), there is valine (non-polar group). Valine is a sticky area to which other sticky areas are attached → deformation of red blood cells.

Polypeptides, proteins

Biological role of proteins and polypeptides

Polypeptides and proteins are the main substances of a living organism. “Life is a form of existence of protein bodies” (F. Engels). Their role in metabolism is unique; they perform all the basic functions of metabolism:

1) Proteins – plastic material of tissues;

2) Protein is one of three types of nutrients needed by the body;

3) Protein structures are key in the composition of enzymes - biochemical catalysts, “engines” of metabolism;

4) Hormones and substances that regulate the paths of biochemical transformations are mainly polypeptides and proteins. Tissue receptors for hormones, bioregulators and drugs are also protein structures.

Primary structure of polypeptides and proteins

Polypeptides and proteins - These are polymers consisting of amino acid residues linked together by peptide bonds.

It is conventionally believed that polypeptides are polymers containing up to 100 amino acid residues; more than 100 residues are proteins. Oligopeptides are especially prominent - up to 10 amino acid residues.

Polypeptides and proteins are formed as a result of polycondensation of α-amino acids:

Physicochemical properties of polypeptides and proteins

Molecules of polypeptides and proteins contain ionic carboxyl and amino groups and, like amino acids, always carry an electrical charge, the sign and magnitude of which depends on the pH of the solution.

All polypeptides and proteins are characterized by a certain isoelectric point (pI) - the pH value at which the total charge of the molecule is zero.

If the pH of the solution below isoelectric point (pH< pI), то молекула в целом имеет positive charge.

If the pH of the solution higher isoelectric point (pH > pI), then the molecule as a whole has negative charge.

If the numbers of carboxyl and amino groups in the molecule are the same, then the isoelectric point of the substance is in the neutral pH region (pI = 7). This neutral polypeptides.

If the molecule is dominated by carboxyl groups, then the isoelectric

the point is in the acidic pH region (pI< 7). Это sour polypeptides.

If amino groups predominate in the molecule, then the isoelectric point is located in the main pH region (pI > 7). This basic polypeptides.

The solubility of polypeptides in water depends on their molecular weight.

Oligopeptides and low molecular weight polypeptides, like amino acids, are highly soluble in water.

High molecular weight proteins form colloidal solutions. Their solubility depends on pH (i.e., the charge of the molecule). At the isoelectric point, protein solubility is minimal and it precipitates. When acidified or alkalized, the molecules become charged again and the precipitate dissolves.

Spatial structure of proteins and polypeptides

High molecular weight polypeptides and proteins, in addition to the primary structure, have higher levels of spatial organization - secondary, tertiary and quaternary structures.

PEPTIDE GROUP

Secondary structure

1) α-helix

The structure of the peptide group determines the spatial structure of the polypeptide chain.

L. Pauling (1950) showed by calculation that for an α-polypeptide chain one of the most probable structures is a right-handed α-pyral. This was soon experimentally confirmed by X-ray structural analysis:

Between the C=O of the 1st and N-H of the 5th amino acid residues, hydrogen bonds are formed, directed almost parallel to the axis of the helix; they hold the helix together. The side radicals R are located along the periphery of the helix.

2) β-sheet structure

In this type of secondary structure, polypeptide chains stretched one along the other form hydrogen bonds with each other:

Many proteins have a secondary structure with alternating fragments of α-helix and β-sheet structure.

Tertiary structure

The α-helix, being sufficiently extended, bends and folds into a ball. This occurs as a result of the interaction of side radicals quite distant from each other. A globule is formed:

Types of interactions that form the tertiary structure

1) Hydrogen bonds

2) Ionic interaction

3) Hydrophobic interaction

4) Disulfide bonds

Quaternary structure

The quaternary structure is an aggregate of subunits - globules. It is formed by the same types of interactions as the tertiary structure:

Quaternary structure of protein Quaternary structure of hemoglobin

Some complex proteins have a quaternary structure - hemoglobin, some enzymes, etc.

LITERATURE:

Main

1. Tyukavkina N.A., Zurabyan S.E., Beloborodov V.L. and others - Organic chemistry (special course), book 2 - Bustard, M., 2008, p. 207-227.

2. Tyukavkina N.A., Baukov Yu.I. – Bioorganic chemistry – DROFA, M., 2007, p. 314-315, 345-369.

Terminology: Oligopeptides and Polypeptides

The line between oligopeptides and polypeptides (the size at which a protein molecule ceases to be considered an oligopeptide and becomes a polypeptide) is quite arbitrary. Often peptides containing less than 10-20 amino acid residues are called oligopeptides, and substances with a large number of amino acid units are polypeptides. In many cases, this line is not drawn at all in the scientific literature and a small protein molecule (such as oxytocin) is referred to as a polypeptide (or simply as a peptide).

Story

Peptides were first isolated from protein hydrolysates obtained by fermentation.

• Term peptide proposed by E. Fischer, who by 1905 had developed a general method for the synthesis of peptides.

In 1953, V. Du Vigneault synthesized oxytocin, the first polypeptide hormone. In 1963, based on the concept of solid-phase peptide synthesis (P. Merrifield), automatic peptide synthesizers were created. The use of polypeptide synthesis methods made it possible to obtain synthetic insulin and other enzymes.

Known "families" of peptides

The peptide families in this section are ribosomal and typically have hormonal activity.

Pancreatic polypeptide molecules

• en:NPY
• Peptide YY
• APP Avian pancreatic polypeptide
• en:HPP Human pancreatic polypeptide

Opioid peptides

Opioid peptides are a group of natural and synthetic peptides similar to opiates (morphine, codeine, etc.) in their ability to bind to opioid receptors in the body. Endogenous morphine-like substances were first isolated in 1975 from the whole brain and pituitary gland of pigeons, guinea pigs, rats, rabbits and mice, and in 1976 fractions of such oligopeptides were found in human cerebrospinal fluid and blood. Various types of these oligopeptides are called endorphins and enkephalins. Opioid receptor ligands have also been found in many peripheral organs, tissues, and biological fluids. The presence of opioids has been shown in the hypothalamus and pituitary gland, blood plasma and cerebrospinal fluid, gastrointestinal tract, lungs, reproductive system organs, immunocompetent tissues and even in the skin. Along with endorphins, so-called exorphins or paraopioids were also discovered - opioid peptides formed during the digestion of food. To date, opioid receptors and their endogenous ligands have been found in almost all organs and tissues of mammals, as well as in animals of lower classification levels, down to protozoa. The main part of opioid peptides is formed by intracellular cleavage of high-molecular-weight precursors, which leads to the formation of a number of biologically active fragments, including opioid peptides. Three such precursors have been identified and most studied: proopiomelanocortin (POMC), proenkephalin A and prodynorphin (proenkephalin B). The composition of POMC (localized mainly in the pituitary gland) includes the amino acid sequences of b-lipotropin, ACTH, a-, b- and g-melanocyte-stimulating hormones, a-, b- and g-endorphins. It has now been established that the main source of enkephalins (methionine-enkephalin and leucine-enkephalin) in the body is proenkephalin A, localized primarily in the adrenal glands. It contains 4 amino acid sequences of met-enkephalin and one leu-enkephalin, as well as a number of extended forms of met-enkephalin: methorfamide, MERGL (met-enkephalin-Arg6-Gly7-Leu8), MERPH (met-enkephalin-Arg6-Phe7) , peptide F and a group of related peptides that make up peptide E: BAM 22, 20, 18, 12, interacting with mu-, kappa- and delta-type opioid receptors. In the structure of another proenkephalin - preproenkephalin B (or prodynorphin) - sequences of a- and b-neoendorphins, dynorphins were found [dynorphin 1-8, 1-17 (A), dynorphin B (rimorphin), 4kD-dynorphin], which have the greatest affinity for OR k-type, as well as leu-enkephalin. Radioreceptor analysis of the binding of endorphins and enkephalins to opioid receptors showed that the affinity of met- and leu-enkephalins for delta-type opioid receptors is higher than for mu-type receptors; b-endorphin has approximately the same affinity for mu- and delta-type opioid receptors; a- and g-endorphins show much less affinity for both types of receptors compared to b-endorphin. Despite the fact that met-enkephalin interacts predominantly with d-type opioid receptors, its analogues with a longer amino acid sequence - methorfamide and BAM peptides (peptides from the adrenal medulla) have the opposite profile of selectivity for interaction with opioid receptors (mu > kappa > delta). Most endogenous opioids can interact with several types of receptors to varying degrees. Thus, b-endorphin with its N-terminal fragment is able to interact with mu- and delta-opioid receptors, and its C-terminus with epsilon receptors. In the skin of amphibians, and then in the brain and some other organs of warm-blooded animals, the 4th precursor of OP was discovered - prodermorphin, which is considered the source of dermorphin (mu-agonist) and deltorphin (delta-agonist). Endogenous peptides that specifically interact with mu-opioid receptors have been found in the central nervous system: Tyr-Pro-Trp-Phe-NH2 and Tyr-Pro-Phe-Phe-NH2, called endomorphins, as well as the peptide nociceptin, which exerts its analgesic effect through opioid-like orphan receptors .

Peptides (Tachykinin peptides)

• Substance P
• en:Kassinin
• Neurokinin A
• en:Eledoisin
• Neurokinin B

Terminology on the topic

• Polypeptides simple linear chain made up of amino acids
• Oligopeptides or simply) peptides- polypeptides with the number of amino acids in the chain up to 30-50
• Tripeptides
• Neuropeptides nerve tissue associated peptides
• Peptide hormones- peptides with hormonal activity

see also

External links

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