61 elements of the periodic table 8 letters. Structure of the platinum atom. Physical and chemical properties of platinum

The special role of proteins in nutrition

Proteins are an essential component of food. Unlike proteins, carbohydrates and fats are not essential components of food. About 100 grams of protein are consumed daily by a healthy adult. Food proteins

- This is the main source of nitrogen for the body. In economic terms, proteins are the most expensive food component. Therefore, the establishment of protein standards in nutrition was very important in the history of biochemistry and medicine.

In the experiments of Karl Voith, the norms for the consumption of dietary protein were first established - 118 g / day, carbohydrates - 500 g / day, fats 56 g / day. M. Rubner was the first to determine that 75% of the nitrogen in the body is found in proteins. He compiled a nitrogen balance (determined how much nitrogen a person loses per day and how much nitrogen is added).

In an adult healthy person there is nitrogen balance - “zero nitrogen balance”(the daily amount of nitrogen excreted from the body corresponds to the amount absorbed).

Positive nitrogen balance(the daily amount of nitrogen excreted from the body is less than the amount absorbed). It is observed only in a growing body or during the restoration of protein structures (for example, during the recovery period from serious illnesses or when building muscle mass).

Negative nitrogen balance(the daily amount of nitrogen excreted from the body is higher than the amount absorbed). It is observed with protein deficiency in the body. Reasons: insufficient amount of protein in food; diseases accompanied by increased destruction of proteins.

In the history of biochemistry, experiments were carried out when a person was fed only carbohydrates and fats (“protein-free diet”). Under these conditions, nitrogen balance was measured. After a few days, the excretion of nitrogen from the body decreased to a certain value, and after that it was maintained for a long time at a constant level: a person lost 53 mg of nitrogen per kg of body weight per day (approximately 4 g of nitrogen per day). This amount of nitrogen corresponds to approximately 23-25g

protein per day. This value was called "WEAR RATIO". Then 10 g of protein was added to the diet daily, and nitrogen excretion increased. But that's it

protein per day) was called the PHYSIOLOGICAL MINIMUM OF PROTEIN.

In 1951, dietary protein standards were proposed: 110-120 grams of protein per

It has now been established that 8 amino acids are essential. The daily requirement for each essential amino acid is 1-1.5 grams, and the body needs 6-9 grams of essential amino acids per day in total. The content of essential amino acids varies among different foods. Therefore, the physiological minimum protein may be different for different products.

How much protein do you need to eat to maintain nitrogen balance? 20 gr. egg white, or 26-27 gr. meat or milk proteins, or 30 gr. potato proteins, or 67 gr. wheat flour proteins. Egg white contains a complete set of amino acids. When eating plant proteins, much more protein is needed to replenish the physiological minimum. Protein requirements for women (58 grams per day) are less than for men (70 g of protein per day) - data from US standards.

DIGESTION AND ABSORPTION OF PROTEINS IN THE GASTROINTESTINAL TRACT

Digestion is not a metabolic process, since it occurs outside the body (in relation to tissues, the lumen of the gastrointestinal tract is the external environment). The task of digestion is to break down (break down) large molecules

lack species specificity. But the energy reserves available in food

lead to a large loss of energy - they are not oxidative. Every day, approximately 100 grams of amino acids are absorbed into the human body, which

break down daily to final products: urea, CO2. During the breakdown process, metabolites necessary for the body are also formed that can perform the functions of hormones, mediators of various processes and other substances (for example: melanins, the hormones adrenaline and thyroxine).

Liver proteins have a half-life of 10 days. For muscle proteins, this period is 80 days. For blood plasma proteins - 14 days, liver - 10 days. But there are proteins that break down quickly (for a2-macroglobulin and insulin, the half-life is 5 minutes).

About 400 g of proteins are resynthesized daily.

The breakdown of proteins into amino acids occurs by hydrolysis - H2 O is added at the site of cleavage of peptide bonds under the action of proteolytic enzymes. Proteolytic enzymes are called PROTEINASES or PROTEASES. There are many different proteinases. But according to the structure of the catalytic center, all proteinases are divided into 4 classes:

1. SERINE PROTEINASES - they contain the amino acids serine and histidine in their catalytic center.

2. CYSTEINE PROTEINASES - cysteine ​​and histidine in the catalytic center.

histidine, glutamic acid and metal ion (carboxypeptidase “A”, collagenase contain Zn2+).

All proteinases differ in the mechanism of catalysis and in the environmental conditions in which they operate. Each protein molecule contains tens, hundreds, and even thousands of peptide bonds. Proteinases do not destroy any peptide bond, but a strictly specific one.

How does one recognize “one’s” connection? This is determined by the structure of the adsorption center of proteinases. Peptide bonds differ only in what

In cases of substrate specificity, the amino acid whose amino group forms a hydrolyzable bond is important. And sometimes both amino acids are important in determining the substrate specificity of the enzyme.

From a practical point of view, all proteinases can be divided into 2 groups according to their substrate specificity:

1. LOW SPECIFIC PROTEINASES

2. HIGHLY SPECIFIC PROTEINASES

LOW SPECIFIC PROTEINASES:

Their adsorption center has a simple structure, their action depends only on those amino acids that form the peptide bond hydrolyzed by this enzyme.

Pepsin This is an enzyme in gastric juice. Synthesized in cells

gastric mucosa in the form of an inactive precursor - pepsinogen. The conversion of inactive pepsinogen into active pepsin occurs in the stomach cavity. When activated, it splits off

	closing active	enzyme center.		Activation
pepsin occurs under the influence of two factors:
a) hydrochloric acid (HCl)
	already formed	active
called		autocatalysis.
Pepsin is a carboxyl proteinase and		catalyzes	hydrolysis of bonds,

formed by the amino acids phenylalanine (Phen) or tyrosine (Tyr) in R 2 - position (see previous figure), as well as connection Lei-Glu. The pH optimum of pepsin is 1.0-2.0 pH, which corresponds to the pH of gastric juice.

(pH=4.5). Rennin also differs from pepsin in its mechanism and specificity of action.

Chymotrypsin.

	Synthesized in the pancreas in the form of inactive
predecessor			chymotrypsinogen.	Activated
	chymotrypsin by active trypsin and by autocatalysis.
Destroys connections		formed by carboxyl		tyrosine group
(Tyr), phenylalanine (Phen) or tryptophan (Tri) - in position R1,
	large hydrophobic radicals of leucine (leu), isoleucine
	and valina (shaft) in the same position R 1 (see picture).
	the active center of chymotrypsin has a hydrophobic pocket, in

which these amino acids are placed.

Trypsin is synthesized in the pancreas in the form of inactive

precursor - trypsinogen. It is activated in the intestinal cavity by the enzyme enteropeptidase with the participation of calcium ions, and is also capable of autocatalysis. Hydrolyzes bonds formed by positively charged amino acids arginine (Arg) and lysine (Lys) in R 1 -position. Its adsorption site is similar to that of chymotrypsin, but there is a negatively charged carboxyl group deep in the hydrophobic pocket.

Elastase.

It is synthesized in the pancreas in the form of an inactive precursor - proelastase. Activated in the intestinal cavity by trypsin. Hydrolyzes peptide bonds into R 1 -position, formed by glycine, alanine and serine.

All of the listed low-specific proteinases belong to ENDOPEPTIDASES because they hydrolyze the bond inside the protein molecule, and not at the ends of the polypeptide chain. Under the action of these proteinases, the polypeptide chain of the protein is split into large fragments. These large fragments are then acted upon by EXOPEPTIDASES, each of which cleaves one amino acid from the ends of the polypeptide chain.

EXOPEPTIDASES.

Carboxypeptidases.

Synthesized in the pancreas. Activated by trypsin in the intestine. They are metalloproteins. “C” end of the protein molecule. There are 2 types: carboxypeptidase “A” and carboxypeptidase “B”.

Carboxypeptidase “A” cleaves amino acids from aromatic (cyclic) radicals, and carboxypeptidase “B” cleaves off lysine and arginine.

Aminopeptidases.

They are synthesized in the intestinal mucosa and activated by trypsin in the intestine. Hydrolyze peptide bonds into“N” end of the protein molecule. There are 2 such enzymes: alanine aminopeptidase and leucine aminopeptidase.

Alanine aminopeptidase cleaves only alanine, and leucine aminopeptidase cleaves off any “N”-terminal amino acids.

DIPEPTIDASES Cleave peptide bonds only in dipeptides.

All described enzymes belong to LOW SPECIFIC PROTEINASES. They are characteristic of the gastrointestinal tract.

absorbed and enter the liver, where they undergo neutralization reactions. For more information about this, see Korovkin’s textbook, pp. 333-335.

Low-specific proteinases are also found in lysosomes.

FUNCTIONS OF LYSOSOMAL LOW SPECIFIC PROTEINASES:

1. They ensure the breakdown of foreign proteins that have entered the cell.

2. They ensure total proteolysis of the cell’s own proteins (especially during cell death).

Thus, total proteolysis is one of the general biological processes necessary not only for intracellular digestion, but also for the renewal of aging proteins of the cell and the body as a whole. But this process is under strict control, which is ensured by special mechanisms that protect proteins from the excessive action of proteases.

MECHANISMS PROTECTING PROTEINS FROM THE ACTION OF PROTEINASES:

1. Cage type protection- spatial isolation of proteinases from those proteins on which they can act. Intracellular proteinases are concentrated within lysosomes and are separated from proteins that they can hydrolyze.

2. Muzzle type protection. The point is that proteinases are produced in the form of inactive precursors (proenzymes): for example, pepsinogen (in the stomach), trypsinogen and chymotrypsinogen (in pancreas). In all these precursors, the active center of the enzyme is covered with a fragment of the polypeptide chain. After hydrolysis of a certain bond, this chain breaks off and the enzyme becomes active.

3. “Chainmail” type protection. Protection of a protein substrate by including any chemical structures into its molecule (protective groups covering peptide bonds). It occurs in three ways:

A) Protein glycosylation. Inclusion of carbohydrate components in protein. Glycoproteins are formed. These carbohydrate components perform some functions (for example, receptor function). In all glycoproteins, the carbohydrate part also provides protection against the action of proteinases.

b) Acetylation of amino groups. Addition of acetic acid residues to

free amino groups in the protein molecule.
		If the proteinase learns the location of its
		actions due to the presence of an amino group, then
		appearance		acetyl
		interferes with the action of proteinase on protein.
	Amidation	carboxyl
groups. The protective effect is similar.

d) Phosphorylation of serine or tyrosine radicals

4. “Watchman” type protection. This is the protection of proteins using endogenous proteinase inhibitors.

Endogenous proteinase inhibitors- these are special proteins or peptides that are specially produced in the cell and can interact with proteinase and block it. Although weak types of bonds are involved in binding, the binding of the proteinase to the endogenous inhibitor is strong. Substrates with high affinity for a given proteinase can displace the inhibitor from its complex with the proteinase, and then it begins to act. There are many such inhibitors in the blood plasma, and if proteinases appear, the inhibitors neutralize them.

Typically, such proteinase inhibitors are specific for

a specific class of proteinases.
		Serine inhibitors			proteinases
The most active plasma inhibitor is alpha 1-antitrypsin.								concentration in
blood approximately 35 nmol/l. Primarily inhibits elastase,								and at large
At concentrations of the inhibitor, trypsin is inhibited.								is being produced
		may be violated		processing	this protein.			result
accumulates		in granules,		stands out	in active form

a genetic defect, and patients homozygous for this trait may develop disorders in the lungs, and then in the liver (emphysema and hepatitis develop).

U heterozygotes - a tendency to develop chronic inflammatory processes.

IN There are other serine proteinase inhibitors in blood plasma: alpha 1 -

antichymotrypsin, antithrombin, alpha2-antiplasmin.

Thiol proteinase inhibitors

One of the most important inhibitors of this group is alpha 2-macroglobulin.

proteinase into a trap that is on the surface of the macroglobulin. With this interaction, the active center of the enzyme is free and low molecular weight substrates

continue	destroyed by proteinase.			But in a "trap"
get closer		sufficient	degree c	protein substrate.				alpha2 -
macroglobulin		not easy	inhibitor,	and the modulator	substrate		specificity

proteinases If macroglobulin traps proteinase, then, for example, plasmin continues to break down fibrin molecules (small sizes). As soon as

Metabolism of simple proteins and amino acids B.220400
alpha2-macroglobulin				traps proteinase			then he immediately changes
		result		freed up			whom	many cells
(leukocytes,			macrophages) have		specific receptors.			Therefore they

bind to the “alpha2-macroglobulin-enzyme” complex, phagocytose it, and in lysosomes the absorbed proteins are completely hydrolyzed to amino acids. Therefore, alpha2-macroglobulin is also called a “cleaner”. 4% of all plasma proteins

macroglobulin is about 5 minutes. This means that in 5 minutes half of the alpha2-macroglobulin contained in the blood plasma is renewed.

HIGHLY SPECIFIC PROTEINASES

The adsorption center of these enzymes has a complex structure. They are capable

which the enzyme hydrolyzes. Often, a highly specific proteinase can recognize and hydrolyze only one bond out of hundreds of others present in a substrate protein. Such highly specific cleavage of a protein molecule in one strictly defined place is called “limited proteolysis”.

Highly specific proteinases can be divided into two groups:

1. Intracellular highly specific proteinases . Provide postsynthetic protein modification. Protein molecules are synthesized in ribosomes in the form of a single polypeptide, which contains many more amino acids than the protein that is then formed from it.

Postsynthetic protein modification involves many different processes that are different for each individual protein.

For example, chemical modification of some amino acid radicals may occur (for example, proline in collagen is converted into hydroxyproline).

After protein synthesis, carbohydrate fragments are added to it. This is how glycosylated proteins are formed. The post-synthetic transformations that accompany limited proteolysis are called “PROTEIN PROCESSING”.

All processing reactions can be divided into two phases: a) cleavage of the “signal” peptide; b) subsequent postsynthetic modification.

Typically, proteins are synthesized in such a way that at the N-terminus of such a protein there is

hydrophobic radicals. Therefore, the signal sequence is very resistant to the action of proteolytic enzymes. The hydrophobicity of the signal sequence allows the protein molecule to penetrate membranes.

There are three main functions of signal peptides:

a) ensure the resistance of the synthesized protein to proteolysis along the entire path of this protein from ribosomes to the place where the protein performs its function in the cell;

b) create conditions for protein transfer through membranes.

Thus, the signal peptides provide protein transport from the site

synthesis to the destination - provide an addressing function.
Even after splitting off	signal peptide formation of the final
protein is not yet complete: a long polypeptide remains			which is still
should be shortened.
Again, a series of limited proteolysis reactions occurs, resulting in
of which the polypeptide chain	shortened in different ways:		is happening

shortening by hydrolysis from the C-terminus; sometimes hydrolysis occurs from the N-terminus; in some cases, the cleavage of the polypeptide occurs in the middle of the chain as a result of hydrolysis in two places.

EXAMPLES OF WORK OF INTRACELLULAR HIGH SPECIFIC PROTEINASES

Example 1: MATURATION OF THE INSULIN HORMONE MOLECULE:

Metabolism of simple proteins and amino acids B.220400
					Ripe		molecule consists of
				two polypeptide chains,
				connected					disulfide
							one chain (A-chain)
				contained				amino acid
				the remainder, and in the second (B-chain) - 30
				amino acid residues.
					It turned out that this protein
				synthesized					the only one
				polypeptide
(PREPROINSULIN),	wherein	contained		100 amino acids				leftovers
hydrolysis from the N-terminus, the signal peptide is detached from the molecule (16
amino acids) and PROINSULIN is formed.					signal		sequences in
preproinsulin	allows		permeate				membranes			straws

endoplasmic reticulum. And the conversion of preproinsulin to proinsulin occurs inside the tubes under the action of a highly specific proteinase.

Then, the second group of processing reactions begins in the Golgi apparatus and is completed in the secretory granules. During these reactions, a B chain is formed, and then from the C-terminus at a distance of 20 amino acid fragments from the end

hydrolysis of the bond between arg79 and gly80 occurs.	Ultimately from the molecule
proinsulin is separated into a 33-membered middle peptide.		As a result		is formed
Example 2. MATURATION OF THE PITUITARY ADRENOCORTICOTROPIC HORMONE (ACTH) MOLECULE.
The protein corticotropin is synthesized in				molecules,
which contains 264 amino acid fragments and is called PROOPIOCORTIN.
ACTH itself is made up of amino acids
from 131st to 170th as part of this
		the remaining areas contain
signaling		subsequence
			molecules	contained
polypeptide from which it is formed
melanocyte-stimulating hormone

During processing, the signal sequence is first cleaved from proopiocortin and then, after two proteolysis reactions, the gamma2-MSH (melanocyte-stimulating hormone) peptide is separated from the N-terminus and the C-terminus. ACTH is released from the N-terminus.

ENDORPHINS (endogenous morphines) are formed. They are peptides in structure. For example, the peptide scotophobin causes fear of the dark in animals (even if it is administered to nocturnal animals, they begin to fear the dark).

Intracellular proteinases that provide processing reactions have high substrate specificity. Each such proteinase acts on one specific protein, and the next proteinase acts only on the product of the first reaction.

The systems of extracellular proteinases are organized completely differently.

EXTRACELLULAR PROTEINASES An example is the blood coagulation system. This is a collection of more than

ten different proteins. Many of these proteins are inactive forms

conformational changes. Its active center, which was previously hidden, protrudes onto the surface of the molecule. This protein is already becoming active and can destroy one peptide bond in another protein, which, as a result of this effect, also turns from a proenzyme into an active enzyme.

For this active enzyme, the substrate is the next plasma protein, which is converted under the action of the second link from the proenzyme into the active enzyme until the process reaches fibrinogen. Another proteolytic

sediment The formed elements of the blood become entangled in this sediment. This is how a blood clot is formed.

It is the high substrate specificity that allows plasma proteinases to form a system in the blood, the links of which work strictly sequentially. This

system - the blood clotting system works according to the principle of cascading. Happening

gradual amplification of an initially weak signal.								Clotting
happens all the time, but			it balances out			process		fibrinolysis.
ensured by the presence of the enzyme plasmin in the blood plasma,							which is formed from
plasminogen and is not part of the coagulation cascade.								Plasmina,
contained in the blood, enough				to ensure hydrolysis of fibrin inside
		violations	fibrinolysis		observed		DIC syndrome
disseminated intravascular coagulation).
	proteolytic systems					relate

COMPLEMENT and VASCULAR TONE REGULATION SYSTEM (using vasoactive peptides). Details about these systems, as well as about the operation of the blood coagulation system, are presented in the lecture “PROTEOLYTIC BLOOD SYSTEMS”.

CATABOLISM OF AMINO ACIDS.

80% of the amino acids that enter the body from the gastrointestinal tract are used for protein synthesis. The remaining 20% ​​enters metabolic processes. All these processes can be divided into 2 groups:

1. Common pathways of amino acid catabolism(they are the same for all amino acids). The common part of the amino acid molecule takes part in them.

2. Specific metabolic pathways for each individual amino acid (different for different amino acids) - amino acid radicals are involved. These are features of the metabolism of individual amino acids.

COMMON PATHS OF AMINO ACIDS CATABOLISM

1. Decarboxylation

2. Deamination

3. Transamination (transamination)

DECARBOXYLATION Various types of amino acid decarboxylation occur in nature. IN

occurs in the human body only oxidative decarboxylation. Enzymes - decarboxylases. Their prosthetic group is represented by pyridoxal phosphate -

This is the active form of vitamin B6:
In decarboxylation reactions	aldehyde group involved
pyridoxal phosphate:
	Amino acid
	connects		active
	enzyme, which contains
	aldehydic
	Are formed
	grounds	(aldimines
	ketimines).		result

The COOH group becomes labile and is eliminated in the form of CO2. Next, hydrolysis occurs to the corresponding amine. This reaction is irreversible. CO2 removal occurs without oxidation.

The substrate specificity of decarboxylases is very different.

1. GLUTAMATE DECARBOXYLASE is a highly specific enzyme. Works in the cells of the gray matter of the brain. Catalyzes the reaction of converting glutamic acid into gamma-aminobutyric acid (GABA).

GABA is a mediator of inhibitory impulses in nervous system. GABA and its analogues are used in medicine as neurotropic agents for the treatment of epilepsy and other diseases.

2. ORNITINE DECARBOXYLASE is a highly specific enzyme. Catalyzes the conversion of ornithine to putrescine:

The resulting putrescine (diaminobutane) is a cadaveric poison. As a result of the addition of residues

propylamine from putrescine, SPERMINE and SPERMIDINE can be formed, containing 3 (for spermine) or 4 (for spermidine) imino or amino groups.

Spermine and spermidine belong to the group of biogenic polyamines. The introduction of polyamines into the body reduces body temperature and blood pressure. Polyamines take part in

squirrel. They are inhibitors of certain enzymes, including protein kinases. Ornithine decarboxylase is the first enzyme in the pathway of putrescine formation

And remaining polyamines, this is a regulatory enzyme of the process.

IN cell culture, the addition of certain hormones accelerates the biosynthesis of ornithine decarboxylase in 10-200 times.

The half-life of ornithine decarboxylase is 10 minutes.

The addition of polyamines themselves to the cell culture leads to the induction of the biosynthesis of another protein - an inhibitor of ornithine decarboxylase. In cancer cases, a sharp increase in the secretion of polyamines and an increase in their excretion in the urine have been found.

3. HISTIDINE DECARBOXYLASE This enzyme has absolute substrate specificity - it converts

histidine to histamine:

Histamine is a neurotransmitter and is found in nerve cells and mast cells. They have a strong vasodilator effect. Especially a lot of it is released at the site of inflammation. Histamine

plays an important role in the manifestation of allergic reactions. There are 2 types of histamine receptors: H1 and H2. Effects of histamine:

- expansion of capillaries and increased vascular permeability;

- decreased blood pressure;

Increased tone (spasm) of smooth muscles -				including smooth	muscles
Increased secretion of gastric juice;
Some of these effects allow histamine to participate in
formation of allergic manifestations.
Antihistamines are used to prevent the formation
histamine	and have	anti-inflammatory		antiallergic effect. By
mechanism	actions	some of them	are inhibitors		histidine-

decarboxylase, while others compete with histamine for interaction with cell receptors.

For example, the drug cimetidine and its analogues block H2 receptors and thus reduce the secretion of gastric juice. Used in the treatment of gastric ulcers.

H1 receptor blockers are used mainly as antiallergic drugs - diphenhydramine, tavegil, suprastin, pipolfen, grandaxin. Some of these drugs cause drowsiness.

4. AROMATIC AMINO ACIDS DECARBOXYLASE Has broad substrate specificity. Transforms several different

amino acids:

a) tryptophan - into tryptamine b) 5-hydroxytryptophan - into tryptamine (serotonin)

c) 3,4-dioxyphenylalanine - into dopamine d) histidine - into histamine

Serotonin is produced in nerve tissue. Some types of headaches (migraines) are associated with excess serotonin production. Serotonin constricts blood vessels and regulates blood clotting. Has anti-allergic effect. Tryptamine has a similar effect.

The amino acid phenylalanine can, as a result of oxidation, attach two OH groups in the ring and turn into

dioxyphenylalanine (DOPA). Dopamine is formed from it under the action of AROMATIC AMINO ACIDS DECARBOXYLASE. Dopamine is a precursor of catecholamines - norepinephrine and adrenaline.

Metabolism of simple proteins and amino acids B.220400
In addition to its precursor function, DOPAamine
has its own specific functions.			If DOPA
methylated	then it is formed	a-methyl-DOPA.
This compound is a strong inhibitor
decarboxylase	aromatic	amino acids.
Used as a medicine for
lowering blood pressure			(called
Aldomet).

BIOLOGICAL SIGNIFICANCE OF AMINO ACIDS DECARBOXYLATION REACTIONS

1. The reactions are irreversible - they lead to the irreversible breakdown of amino acids.

2. A significant amount of CO is formed 2 - the final product of metabolism, which is excreted from the body.

3. Amines are formed, which have high biological activity. Therefore, such amines are calledbiologically active or biogenic amines. They

are mediators through which a signal is transmitted from one cell to another and from one molecule to another.

INACTIVATION OF BIOGENIC AMINES If biogenic amines have high biological activity, then they

must degrade quickly after performing their function.

The body has mechanisms that allow it to destroy biogenic amines. INACTIVATION MECHANISMS:

1. Methylation at hydroxy groups those amines that contain such groups, or include hydroxy groups in their molecule after hydroxylation.

Enzymes - O-METHYL TRANSFERASES. They transfer a methyl group to oxygen. Source of methyl radical: S-Adenosylmethionine.

After the addition of the adenyl residue of ADP to the sulfur of methionine, the methyl group of methionine becomes very mobile and is easily transferred to different substances. Including oxygen hydroxy groups.

2. Oxidation of an amine at the amino group for the purpose of deamination.

The main way of inactivation of biogenic amines is their oxidation under the action of oxidases with elimination of the amino group. As a result, the biological activity of the amine disappears.

Biogenic amine oxidases: monoamine oxidase (MAO), diamine oxidase (DAO), polyamine oxidase.

Oxidases take away two protons and two electrons and transfer them directly to oxygen. Hydrogen peroxide is formed and the amine is converted to IMIN. This imin

easily hydrolyzes without the participation of an enzyme and turns into an aldehyde. The prosthetic group of oxidase enzymes is FAD or FMN, i.e. they are flavoproteins.

The second reaction (hydrolysis) is irreversible. The resulting aldehyde is easily oxidized to a carboxylic acid, which decomposes to CO2 and H2 O. There is more MAO in the cell than DAO.

Inhibition of MAO will slow down the breakdown of biogenic amines. Such drugs prolong the period of existence of biogenic amines, which is especially important in case of their deficiency.

These substances play the role of antidepressants and are used, in particular, for

Since the decarboxylation of amino acids and the destruction of biogenic amines do not occur simultaneously, biogenic amines can exist for some time and perform their biological function.

DEAMINATION OF AMINO ACIDS In humans occurs mainly through oxidative deamination. These

reactions occur with the help of two enzymes: - D-amino acid oxidase

L-amino acid oxidase

These enzymes are group stereospecific. Oxidases are taken away

protons and electrons from amino acids using this				the same mechanism
oxidases	providing deamination	biogenic					enzymes
are flavoproteins and contain as prosthetic
						is formed
	imino acid,
	spontaneous hydrolysis produces alpha
	keto acid.
		In addition to oxidases, there is another
			catalytic			oxidative
	deamination			glutamic acid
	glutamate dehydrogenase (glutamateDH).
					is

dependent and has high activity (like other NAD-dependent

dehydrogenase).			Unlike	amino acid oxidases, which				slowly
convert amino acids under physiological conditions (therefore
saved	majority		amino acids).			glutamate-DG		is
nicotinamide,		protons taken away			electrons are not	are transmitted

oxygen, but are transported along the complete MTO chain with the formation of water and

parallel formation of three ATP molecules.
Glutamate-DG			has
activity and this differs from MAO and
DAO. Glutamate-DG is regulatory
enzyme		it is inhibited		excess
ATP, and is activated by excess ADP.
BIOLOGICAL			MEANING
DEAMINATION
			deamination
irreversible, like decarboxylation reactions		deamination can also

play the role of the first step in the breakdown of amino acids.

2. One of the direct products of deamination is the end product of ammonia metabolism. This is a toxic substance. Therefore, cells must expend energy to neutralize ammonia into harmless products that are excreted from the body.

3. Another product of the deamination reaction is an alpha-keto acid.

All resulting alpha-keto acids are easily broken down further to CO2 and H2 O (for example, alanine is converted into PVA (by deamination; aspartate - into PKA; glutamic acid - into alpha-ketoglutaric acid). Most alpha-keto acids are converted in one way or another into acids which are intermediate metabolites of the TCA cycle:

B alpha-ketoglutaric;

To amber;

Fumarova;

- oxalo-vinegar. All these metabolites can be transformed in the body

into carbohydrates, before turning into PVC. Therefore, most amino acids belong to a group called GLUCOGENIC AMINO ACIDS (there are 17 of them). Only 3 amino acids cannot be converted into PVC, but are converted into Ac-CoA - KETOGENIC AMINO ACIDS : leucine, lysine, tryptophan). They can be directly transformed into fatty acids or ketone bodies.

The metabolic pathways into which amino acids enter after deamination are no longer the actual pathways of amino acid metabolism, but are universal for amino acids, carbohydrates, and fats.

TRANSAMINATION This reaction is that

an amino acid and a keto acid exchange their functional groups with each other at the alpha carbon atom. As a result, the reacted amino acid is converted into the corresponding alpha-keto acid, and

the keto acid becomes an amino acid.

We have come to the most important aspect in planning an athlete's nutrition. The topic of our article is protein metabolic processes. In the new material you will find answers to the questions: what is protein metabolism, what role do proteins and amino acids play in the body, and what happens if protein metabolism is disrupted.

General essence

Most of our cells are made of protein. This is the basis of the body’s vital activity and its building material.

Proteins regulate the following processes:

• brain activity;
• digestion of trihydroglycerides;
• synthesis of hormones;
• transmission and storage of information;
• movement;
• protection from aggressive factors;

Note: the presence of protein is directly related to insulin synthesis. Without a sufficient amount from which this element is synthesized, an increase in blood sugar becomes only a matter of time.

• creation of new cells - in particular, liver cells regenerate due to protein structures;
• transport of lipids and other important compounds;
• converting lipid bonds into joint lubricants;
• metabolic control.



And dozens more different functions. In fact, protein is us. Therefore, people who refuse to eat meat and other animal products are still forced to look for alternative sources of protein. Otherwise, their vegetarian life will be accompanied by dysfunctions and pathological irreversible changes.

As strange as it may sound, many foods contain a small percentage of protein. For example, cereals (all except semolina) contain up to 8% protein, albeit with an incomplete amino acid composition. This partially compensates for the protein deficiency if you want to save on meat and sports nutrition. But remember that the body needs different proteins - buckwheat alone will not satisfy the needs for amino acids. Not all proteins are broken down equally and all have different effects on the body's activities.




In the digestive tract, protein is broken down under the influence of special enzymes, which also consist of protein structures. In fact, this is a vicious circle: if the body has a long-term deficiency of protein tissues, then new proteins will not be able to denature into simple amino acids, which will cause an even greater deficiency.

Important fact: proteins can participate in energy metabolism along with lipids and carbohydrates. The fact is that glucose is an irreversible and the simplest structure that is converted into energy. In turn, protein, albeit with significant energy losses in the process of final denaturation, can be converted into. In other words, the body in a critical situation is able to use protein as fuel.

Unlike carbohydrates and fats, proteins are absorbed exactly in the amount necessary for the functioning of the body (including maintaining a constant anabolic background). The body does not store any excess protein. The only thing that can change this balance is taking analogs of the hormone testosterone (anabolic steroids). The primary task of such drugs is not at all to increase strength indicators, but to increase the synthesis of ATP and protein structures, due to which.

Stages of protein metabolism

Protein metabolic processes are much more complex than carbohydrate and. After all, if carbohydrates are just energy, and fatty acids enter cells almost unchanged, then the main builder of muscle tissue undergoes a number of changes in the body. At some stages, protein can even be metabolized into carbohydrates and, accordingly, into energy.



Let's consider the main stages of protein metabolism in the human body, starting with their entry and sealing of future amino acids with denatured alcohol by saliva and ending with the final products of vital activity.

Note: We will superficially look at the biochemical processes that will allow us to understand the very principle of protein digestion. This will be enough to achieve sports results. However, in case of protein metabolism disorders, it is better to consult a doctor who will determine the cause of the pathology and help eliminate it at the level of hormones or the synthesis of the cells themselves.

Stage	What's happening	The essence
Primary hit of proteins	Under the influence of saliva, the main glycogen bonds are broken down, turning into the simplest glucose, the remaining fragments are sealed for subsequent transportation.	At this stage, the main protein tissues in the food are separated into separate structures, which will then be digested.
Digestion of proteins	Under the influence of pancreatin and other enzymes, further denaturation occurs to first-order proteins.	The body is configured in such a way that it can obtain amino acids only from the simplest chains of proteins, for which it acts with acid to make the protein more degradable.
Breakdown into amino acids	Under the influence of cells of the inner mucous membrane of the intestine, denatured proteins are absorbed into the blood.	The body breaks down the simplified protein into amino acids.
Splitting to energy	Under the influence of a huge amount of insulin substitutes and enzymes for digesting carbohydrates, protein breaks down into the simplest glucose	In conditions when the body lacks energy, it does not denature the protein, but with the help of special substances breaks it down immediately to the level of pure energy.
Redistribution of amino acid tissues	Circulating in the general bloodstream, protein tissues, under the influence of insulin, are transported throughout all cells, building the necessary amino acid bonds.	Proteins, traveling throughout the body, restore the missing parts, both in muscle structures and in structures associated with hormonal stimulation, brain activity or subsequent fermentation.
Composition of new protein tissues	In muscle tissue, amino acid structures bind to micro-tears to form new tissue, causing hypertrophy of muscle fibers.	Amino acids in the right composition are converted into muscle-protein tissue.
Secondary protein metabolism	If there is an excess of protein tissue in the body, under the secondary influence of insulin they again enter the bloodstream to be converted into other structures.	When there is severe muscle tension, prolonged fasting, or during illness, the body uses muscle proteins to compensate for amino acid deficiencies in other tissues.
Transport of lipid tissues	Freely circulating proteins linked to the lipase enzyme help transport and digest polyunsaturated fatty acids along with bile.	Protein is involved in the transport of fats and the synthesis of cholesterol from them. Depending on the amino acid composition of the protein, both good and bad cholesterol are synthesized.
Removal of oxidized elements (end products)	Spent amino acids are excreted through the process of catabolism with waste products of the body.	Muscle tissue damaged as a result of stress is transported out of the body.

Protein metabolism disorder

Protein metabolism disorders are no less dangerous for the body than pathologies of fat and carbohydrate metabolism. Proteins are involved not only in muscle formation, but in almost all physiological processes.

What could go wrong? As we all know, the most important energy element in the body is ATP molecules, which, traveling through the blood, distribute the necessary energy to cells. When protein metabolism is disrupted, ATP synthesis “breaks” and processes that indirectly or directly affect the synthesis of new protein structures from amino acids are disrupted.

Among the most likely consequences of metabolic disorders:

• acute pancreatitis;
• necrosis of stomach tissue;
• cancerous tumors;
• general swelling of the body;
• violation of water-salt balance;
• weight loss;
• slowdown mental development and growth in children;
• inability to digest fatty acids;
• the inability to transport waste products through the intestines without irritating the vascular walls;
• sharp
• destruction of bone and muscle tissue;
• destruction of the neuron-muscle connection;
• obesity;
• Under the influence of changes in hormonal balance, catabolic reactions prevail over anabolic ones.
• Without protein from food, there is a lack of basic synthesized amino acids.
• In the absence of sufficient carbohydrate intake, residual proteins are catabolized into sugar metabolites.
• Complete absence of fat layer.
• There are pathologies of the kidneys and liver.

Bottom line

The metabolism of proteins in the human body is a complex process that requires study and attention. However, to maintain a confident anabolic background with the correct redistribution of protein structures into subsequent amino acids, it is enough to follow simple recommendations:

1. Protein intake per kilogram of body is different for a trained and untrained person (athlete and non-athlete).
2. For full metabolism, you need not only carbohydrates and proteins, but also fats.
3. Fasting always leads to the destruction of protein tissue to replenish energy reserves.
4. Proteins are primarily consumers, not carriers, of energy.
5. Optimization processes in the body are aimed at reducing energy consumption in order to preserve resources for a long time.
6. Proteins are not only muscle tissue, but also enzymes, brain activity and many other processes in the body.

AND main advice for athletes: do not get carried away with soy protein, since of all protein shakes it has the weakest amino acid composition. Moreover, a poorly cleaned product can lead to catastrophic consequences - changes in hormonal levels and... Long-term consumption of soy is fraught with a deficiency of irreplaceable amino acids in the body, which will be the root cause of disruption of protein synthesis.

Light silver in color, shiny and does not fade when exposed to air. In addition, platinum is a very refractory, durable and at the same time malleable metal, however, this is typical for many platinoids. Platinum is a rather rare and valuable metal, found much less frequently in the earth’s crust than, for example, gold or silver. By the way, it got its name thanks to the latter. In Spanish, "plata" means silver, and "platina" means like silver.

The exact date of platinum's discovery is unknown, as it was discovered by the Incas in South America. In Europe, the first mentions of platinum (as an unknown metal that cannot be melted - since its melting point is almost 1770 degrees Celsius) appear in the 16th century thanks to the conquests of the Spanish conquistadors. However, regular supplies of platinum to Western Europe from South America began only in XVII-XVIII centuries. Officially, it began to be considered a new metal among European scientists only in 1789, after the publication of his “List of Simple Substances” by the French chemist Lavoisier.

Pure platinum, without foreign impurities, was extracted from platinum ore already in 1803 by the British scientist William Wollaston. At the same time, he simultaneously discovered two more platinoids (platinum group metals) from the same ore - palladium and rhodium. It is interesting that Wollaston was originally a doctor who became interested in the production of medical utensils and instruments from platinum - because of its bactericidal properties and incredible resistance to oxidizing agents. It was he who first discovered that the only substances that can affect platinum in natural conditions are “regia vodka” (a mixture of concentrated hydrochloric and sulfuric, or nitric acid), as well as liquid bromine.

Platinum deposit and mining.

First platinum deposit discovered many centuries ago by the Incas in South America, and until the 19th century it was the only known source of platinum in the world. In 1819, platinum was discovered in the Russian Empire, in what is now the Krasnoyarsk region in Siberia. For a long time this noble metal was not identified and was referred to as “ White gold"or simply "new Siberian metal". Full-fledged platinum mining in Russia began by the end of the first half of the 19th century - with the invention by Russian scientists of that time of a new technique for forging platinum in a hot state.

In our time, South American deposits in the Andes have begun to deplete and the main promising areas platinum mining are located on the territory of only five states:

• Russia (Ural and Siberia);
• China;
• Zimbabwe.

In the 19th and very early 20th centuries Russian empire became the main supplier of platinum to the world market - from 90 to 95 percent of all platinum supply. This continued until this noble metal was overvalued and acquired strategic importance. However, although this happened in the second half of the 19th century (then all issued platinum coins in Russia were withdrawn from circulation during the reigns of Paul I and Nicholas I), supplies of platinum to Europe under Alexander II continued. Already during the times of the Soviet Union, all data on platinum mining were strictly classified, and remain so to this day - already in the Russian Federation. Therefore, Russia is rated as the 3rd or 4th country in terms of platinum mining in the world, very conditional. And no one even knows approximately how much platinum is stored in the strategic reserves of the Russian Federation.

On this moment What is known for certain is that the leader in platinum mining in Russia is the state-owned company Norilsk Nickel. The officially published volume of production of this metal in the 2000s averaged about 20-25 tons of platinum per year. At the same time, South Africa supplies about 150 tons per year to the international market. Already in our time, a new platinum deposit was discovered in the Khabarovsk Territory (a fairly large deposit), but its official production is only 3 to 4 tons per year.

Currently discovered deposits platinum in the world suggest potential production of about 80 thousand tons of this metal. Most of them are in South Africa (more than 87 percent). In Russia - more than 8%. And in the States - up to 3%. Again, these are official published data. Do not forget that not every country will want to disclose the contents of its strategic storage facilities precious metals and production potential.

Application of platinum.

Platinum, like most platinoids, has the same areas of application:

• jewelry industry;
• dentistry;
• chemical industry (due to its catalytic properties);
• electronics and electrical engineering;
• medicine (ware and instruments);
• pharmaceuticals (medicines, mainly oncological);
• astronautics (almost eternal soldering of platinum contacts does not require repair);
• laser production (platinum is part of most mirror elements);
• electroplating (for example, non-corrosion parts of submarines);
• production of thermometers.

Platinum prices and price dynamics.

Initially platinum price(when it was brought to Europe in the 17th century) was very low. Despite the beauty of the new metal, they could not melt it and really use it anywhere. At the beginning of the 18th century, when technology made it possible to melt it, counterfeiters began to use platinum to counterfeit Spanish gold reals. Then the Spanish king seized almost all the platinum and solemnly sank it in the Mediterranean Sea, and prohibited further deliveries.

All this time platinum price did not exceed half the price of silver.

With the development of new technologies in the early 19th century and the isolation of pure platinum by Wollaston, platinum began to be used in various industries, and its price reached that of gold.

In the twentieth century, after realizing the advantages of platinum in physical and chemical properties compared to gold, its price continued to rise. The demand for platinum as a high-quality chemical catalyst increased in the 70s of the last century, when the global automotive boom began. This noble metal was used to purify exhaust gases (usually alloyed with other platinoids). It was then that chemists discovered that in a finely dispersed state (that is, atomized form), platinum actively interacts with the hydrogen component (CH) of the exhaust gases of internal combustion engines.

The financial downturns and crises of the 2000s and 2010s affected demand and platinum price dynamics. During this period (especially in the 2000s), platinum prices fell below a thousand dollars (almost 900) per troy ounce of the precious metal. Over the past 10 years, platinum prices below $1,000 per ounce have been considered unprofitable. It is therefore not surprising that some of the (mainly South African) platinum mining enterprises have closed. Because of this, a certain shortage arose " white gold” in platinum supply-demand relationships in the 2010s, and its price jumped again. However, the decline in Chinese car production in 2014-2015 caused a new decline in platinum prices.

The average price per ounce of platinum in the first half of 2015 was about $1,100. However, experts have their own platinum price forecast. In their opinion, in 2016, the level of the world economy will grow, and China will resume large-scale automobile production, and the price per troy ounce of platinum will exceed at least $1,300, and another platinum compound, palladium, will cost more than $850 per troy ounce.

Moreover, the fact that the Russian Federation still keeps its platinum reserves, means that this metal has growth prospects, and, therefore, deserves attention for long-term investing (or, at a minimum, preserving your financial assets).

Indicated by Pt.

History of platinum

The ancient world already knew the metal platinum. During archaeological excavations in Egypt, in the ruins of ancient Thebes, an artistic case was found, attributed by experts to the 7th century. BC e. In this relic ancient world there was a grain of iridium-rich platinum.

At the beginning of the 1st century. n. e. gold sand miners in Spain and Portugal began to show noticeable interest in beneficial use“white lead”, or “white gold”, as platinum was then called. According to the testimony of the Roman writer Pliny the Elder (author of the 37-volume book “Natural History”), “white lead” was mined from the gold deposits of Valissia (Northwestern Spain) and Lusitania (Portugal). Pliny says that during washing, “white lead” was collected along with gold at the bottom of baskets and melted separately.

Long before the capture of South America by the Spanish and Portuguese conquistadors, platinum was mined by a cultured native people - the Incas, who not only owned the secret of refining and forging this precious metal, but also knew how to skillfully make it into various items and decorations.

The era of the fall of the Roman Empire is marked by the disappearance of jewelers and dealers in platinum jewelry from everyday life. Many centuries passed, and only in the second half of the 18th century. Scientists began to become interested in platinum and its physicochemical properties.

In 1735, the Spanish mathematician Antonio de Ulloa, while in Equatorial Colombia, drew attention to the frequent presence together with gold of an unknown metal, the shine of which was somewhat reminiscent of the shine of silver, but in all other qualities it was more like gold. This strange metal interested de Ulloa, and he brought samples of Colombian platinum to Spain.

In the 18th century, when platinum did not yet have industrial use, it was mixed with gold and gold and silver products. The Spanish government learned about this “damage” of precious metals. Fearing the possibility of mass counterfeiting of gold coins, it decided to destroy all platinum mined together with gold in the kingdom's colonial possessions. In 1735, a decree was issued ordering the destruction of all platinum mined in Colombia. This decree was in effect for several decades. Special officials, in the presence of witnesses, periodically threw cash reserves of platinum into the river.

At the end of the 18th century. the Spanish kings themselves began to “spoil” gold coin, mixing platinum into it.

Technical uses of platinum

In 1752, the director of the Swedish mint, Schaeffer, announced his discovery of a new chemical element - platinum. Platinum's satellites - palladium, iridium, rhodium, ruthenium and osmium - were discovered much later, in the 19th century. Six listed chemical elements, standing in the eighth group of the periodic table of Mendeleev, form a group called platinum metals. All of these metals have many similar physical and chemical properties and are mostly found together in nature.

At the dawn of the introduction of platinum into technology, scientists dealt with it mostly out of curiosity, but as they studied the properties of platinum in depth, it quickly began to find wide application, especially in the chemical industry. It turned out that platinum is soluble only in aqua regia, insoluble in acids and constant when heated.

Following the appearance of the first samples of chemical glassware made from platinum, it began to be used for the manufacture of distillation apparatus for sulfuric acid. From that moment on, the growth of platinum processing began to increase sharply, as it began to be used in the production of acid-resistant and heat-resistant laboratory chemical equipment, instruments and various devices (crucibles, flasks, cauldrons, tongs, etc.).

Pyrometry uses the exceptional resistance of platinum and its alloys to high temperatures.

The valuable and sometimes irreplaceable properties of platinum and palladium have long been used in catalytic processes. A significant amount of platinum is spent on the manufacture of contact for sulfuric acid plants, where it serves as a catalyst for the oxidation of sulfur dioxide into sulfuric anhydride. Platinum in the form of a grid serves as a catalyst for the oxidation of ammonia in devices of various systems. Numerous organic syntheses also require the use of a platinum catalyst. Palladium catalyst is used in the production of synthetic ammonia and in the production of certain organic drugs. Osmium is also used in the production of synthetic ammonia according to Haber-Rosennell.

In electrical engineering, platinum metals are usually used in the form of alloys. Far from it full list parts of electrical devices where platinum alloys are used: burning needles, instruments for electrical measurements, electrodes (cathodes and anti-cathodes for X-ray tubes), wires and tapes for resistance of electric furnaces, magneto contacts (cars, internal combustion engines), contact points (telegraphy, telephony), lightning rod tips, etc.

In electrochemistry, platinum is used in the production of various electrolytic products. Medicine and dentistry are among the oldest consumers of platinum. We also note the use of platinum for surgery in the form of tips for devices used for cauterization, syringes for injection and infusion, etc.

Jewelry art occupies a leading position as a consumer of platinum in the form of alloys. Platinum gemstone settings provide better shine and purer water than settings made from other precious metals.

Finally, in the form of salts, platinum and its satellites are required for photography, for the manufacture of medicines (rhodium and ruthenium salts) and for the preparation of porcelain paints (rhodium, iridium - black paint, palladium - silver).

Platinum is also used in military applications, for example, for the manufacture of contacts used to produce detonation when mines explode, etc.

Application of platinum

Platinum mining

The first place in world platinum mining belongs to the Ontario region in Canada. Here, in 1856, large deposits of Sudbury copper-nickel ores were discovered, which contain platinum along with gold and silver.

Before the First World War, Canadian platinum did not attract attention, and practical interest in it arose only in 1919, when, as a result of the civil war in the Urals, the production of Russian platinum fell sharply, and the world market began to feel a great shortage of this valuable metal. Since 1919, the sludge from the Sudbury copper-nickel production has been subjected to thorough processing in order to extract platinum group metals, especially since the cost of associated mining of platinum and its satellites is very low.

Russia ranks second in the world in platinum mining. Significant quantities of platinum are mined in Colombia. Other platinum-producing countries include Ethiopia and Congo. Platinum extracted directly from the subsoil, as well as platinum obtained from ores, is subjected to special processing or refining. Refining consists of the usual processes used on a small scale in the practice of analytical laboratories - dissolution, evaporation, filtration, precipitation, etc. As a result of these operations, pure platinum and separately its satellites are obtained.

Platinum mining

Platinum deposits in Russia

The main platinum-bearing province of the Urals is the western zone of deep-seated igneous rocks, which can be continuously traced for 300 km in the Middle Urals region. Platinum deposits in this zone are mainly associated with igneous rocks. During the weathering and destruction of these rocks and when the weathering products are washed away by rivers, pure platinum placers are formed, which are an exceptional feature of the Urals and have provided the bulk of the platinum mined so far.

In the area of ​​the eastern zone of deep igneous rocks there are a number of less valuable platinum deposits. Here platinum is found together with gold and iridium osmide. Due to the destruction and erosion of these rocks, mixed gold-platinum and gold-osmist-iridium-platinum placers are formed, which are less valuable from the point of view of platinum extraction, which is only an admixture to gold here.

Ural platinum before the war of 1914-1918. took first place in the world market. In the first half of the 19th century. (from 1828 to 1839) in Russia, coins were minted from Ural platinum. However, the minting of such a coin was stopped due to the instability of the platinum exchange rate and the import of counterfeit coins into Russia.

Despite the fact that in Russia, platinum refining began immediately after the discovery of platinum deposits in the Urals. Before the revolution, the amount of platinum processed in our country was only 10-13% of the mined metal. Most of the raw platinum and refining semi-products were exported abroad.

In Moscow, there has been a refinery for more than 100 years, where they engage in mechanical processing of refined platinum and alloys. It also produces forging, rolling, wire drawing, chemical glassware, electrode grids, contacts, pyrometers, electric heating devices and other products.

Moscow Refinery

Platinum (English Platinum, French Platine, German Platin) was probably known in ancient times. The first description of platinum as a highly fire-resistant metal, which can be melted only with the help of “Spanish art,” was made by the Italian physician Scalinger in 1557. Apparently, it was then that the metal received its name “platinum.” It reflects a disdainful attitude towards metal, as something of little use and not amenable to processing. The word "platinum" comes from the Spanish name for silver - plate (Plata) and is a diminutive form of this word, which in Russian sounds like silver, silver (according to Mendeleev - silver). It is interesting to note that the word platinum is consonant with the Russian “plata” (to pay, payment, etc.) and is close to it in meaning. In the 17th century platinum was called Platina del Pinto because it was mined from the golden sand of the Pinto River in South America; there was another name of this kind - Platina del Tinto from the Rio del Tinto river in Andalusia. Platinum was described in more detail in 1748 by de Walloa, a Spanish mathematician, navigator and merchant. Starting from the second half of the 18th century. Many analytical chemists and technologists, including scientists from the St. Petersburg Academy of Sciences, became interested in platinum, its properties, methods of processing and use. The most important work in this area in the first half of the 19th century was the creation of methods for producing malleable platinum (Sobolevsky, Wollaston, etc.), the discovery of some of its compounds (Musin-Pushkin, etc.) and platinum group metals.