RELATE:

Formulas:

I) CH 3 - CH 2 - NH - CH

II) C6H5 - NH2

III) CH3 - CH2 - NH2

Amine type:

1) primary

2) secondary

3) tertiary

Name:

a) aniline

b) methylethylanine

c) dimethylisopropylamine

d) ethylamine

In the amine molecule, the effect of the C6H5 radical on the group NH 2 shows up as:

1. the electron density on the nitrogen atom increases

2. the main properties are enhanced

3. the properties of a substance as the base weakens

4. no noticeable changes in the properties of the substance are observed.

When interacting with what substance does diethylamine form a salt?

A white precipitate is formed when aniline reacts with a solution:

1. sulfuric acid

3.potassium hydroxide

4. acetic acid

Lesson topic: Proteins are the basis of organic life.

“Life is a way of existence of protein bodies ...” (F. Engels)

Muscles - 80%;

Kidneys - 72%;

Skin - 63%;

Liver - 57%;

Brain - 45%;

Adipose tissue, bones, teeth - 14 - 28%;

Plant seeds - 10 - 15%;

Stems, roots, leaves - 3% - 5%

Fruits - 1-2%

Chemical composition

Protein contains the following chemical elements:

C, H, O, N, S, P, Fe.

Mass fraction of elements:

C - 50% - 55%;

O - 19% - 24%;

H - 6.5% - 7.3%;

N – 15% – 19%;

S – 0,3% - 2,5%;

P – 0,1% - 2%

Squirrels - high-molecular natural compounds (biopolymers), consisting of amino acid residues, which are connected by a peptide bond.

In nature, there are about 100 α-amino acids,

found in the body 25

each protein has 20, of which 2,432,902,008,176,640,000 combinations can be formed.

The main structural components of proteins are amino acids.

NH2-CH-COOH

General formula

Amino acids-organic compounds that necessarily contain two functional groups: an amino group - NH 2 and a carboxyl group - COOH, associated with a hydrocarbon radical.

AMINO ACIDS

• Interchangeable amino acids - they can be synthesized in the body

2. Essential- they are not formed in the body, they are obtained with food (lysine, valine, leucine, isoleucine, thyreonine, phenylalanine, tryptophan, tyrosine, methionine)

Peptide bond formation

• Amino acids can react with each other: the carboxyl group of one amino acid reacts with the amino group of another amino acid to form a peptide bond and a water molecule.

NH 2 - CH 2 - COOH + NH 2 - CH 2 - COOH =

NH 2 - CH 2 - CO - NH - CH 2 - COOH + H 2 O

• The bond - CO - NH - connecting individual amino acids into a peptide is called a peptide bond.

Methods for obtaining amino acids

industrial

acetic acid →chloroacetic acid→aminoacetic acid

1. CH 3 -COOH + C l 2 → CH 2 -COOH

2. CH 2 -COOH+ NH 3 → CH 2 -COOH

| |

FROM l NH 2

protein hydrolysis

Properties of amino acids:

With acids

NH2 - CH 2 - COOH + HC l → C l

as a basis

With bases

NH2 - CH 2 - COOH + Na OH → NH2 - CH 2 - COONa + H2O

like acid

Conclusion:

AMINO ACIDS - organic amphoteric compounds

Composition and classification of proteins

Proteins are made up of only amino acids.

Proteins - contain a non-protein part.

Complex proteins ( may include carbohydrates (glycoproteins), fats (lipoproteins), nucleic acids (nucleoproteins).

Complete- contain the entire set of amino acids.

Defective Some amino acids are missing.

Primary Structure - the sequence of alternation of amino acid residues in the polypeptide chain.

secondary structure - arises due to the twisting of the primary structure into a spiral or into an accordion due to hydrogen bonds between adjacent turns or links.

β - helix

α-helix

Tertiary structure is the three-dimensional configuration that a twisted helix takes in space.

It is formed due to hydrophobic bonds between amino acid radicals of the secondary structure

The tertiary structure explains the specificity of the protein molecule and its biological activity.

Quaternary structure –

arrangement in space of several polypeptide chains, each of which has its own primary, secondary and tertiary structure and is called subunit .

Classic example: hemoglobin, chlorophyll.

In hemoglobin, heme is the non-protein portion and globin is the protein portion.

• Proteins treated with sodium chloride salted out from a solution. This process is reversible.

• Acids, alkalis and high temperatures destroy the structure of proteins and lead to their denaturation .
• Proteins also denature under the influence of alcohol and heavy metals.
• The process of restoring the structure of a protein is called renaturation .

(Xantoprotein reaction)

(Biuret reaction)

Functions of proteins

Construction (plastic) – proteins are involved in the formation of the cell membrane, organelles and cell membranes.

catalytic – all cellular catalysts are proteins (enzyme active sites).

Motor – contractile proteins cause all movement.

Transport - blood protein hemoglobin attaches oxygen and carries it to all tissues.

Protective – production of protein bodies and antibodies to neutralize foreign substances.

Energy - 1 g of protein is equivalent to 17.6 kJ.

Receptor – response to an external stimulus

CONCLUSIONS:

• squirrels- These are high-molecular organic compounds, biopolymers, consisting of monomers - amino acids.

• amino acids linked to form a polypeptide chain by a peptide bond.

• amino acids - interchangeable and irreplaceable.

• squirrels can be simple or complex.
• four protein structures ( primary, secondary, tertiary and quaternary).

• denaturation- this is the loss by a protein molecule of its structural organization, which provides the functional properties of the protein.

• renaturation- the process of restoring the structure of the protein.

Proteins, or protein substances, are high-molecular (molecular weight varies from 5-10 thousand to 1 million or more) natural polymers, the molecules of which are built from amino acid residues connected by an amide (peptide) bond. catalytic (enzymes); regulatory (hormones); structural (collagen, fibroin); motor (myosin); transport (hemoglobin, myoglobin); protective (immunoglobulins, interferon); spare (casein, albumin, gliadin). Among proteins there are antibiotics and substances that have a toxic effect. Proteins are the basis of biomembranes, the most important part of the cell and cellular components. They play a key role in the life of the cell, leaving, as it were, the material basis of its chemical activity. An exceptional property of a protein is the self-organization of the structure, i.e. its ability to spontaneously create a specific spatial structure peculiar only to a given protein. Essentially, all the activities of the body (development, movement, performance of various functions, and much more) are associated with protein substances. It is impossible to imagine life without proteins. Proteins are the most important component of human and animal food, the supplier of the amino acids they need. WATER - 65% FATS - 10% PROTEINS - 18% CARBOHYDRATES - 5% Other inorganic and organic substances - 2% In protein molecules, α - amino acids are interconnected by peptide (-CO-NH-) bonds ... N CH C N CH C N CH C N CH C ... H R ОН R1 ОН R2 O Н R3 O The polypeptide chains constructed in this way or separate sections within the polypeptide chain can in some cases be additionally linked by disulfide (-S-S-) bonds, or, as their often called disulfide bridges. Ionic (salt) and hydrogen bonds, as well as hydrophobic interaction, a special type of contact between the hydrophobic components of protein molecules in an aqueous medium, play an important role in creating the structure of proteins. All these bonds have different strengths and provide the formation of a complex, large protein molecule. Despite the difference in the structure and functions of protein substances, their elemental composition fluctuates slightly (in % of dry mass): carbon-51-53; oxygen-21.5-23.5; nitrogen-16.8-18.4; hydrogen-6.5-7.3; sulfur-0.3-2.5 Some proteins contain small amounts of phosphorus, selenium and other elements. The sequence of amino acid residues in the polypeptide chain is called the primary structure of the protein. The total number of different types of proteins in all types of living organisms is 1010-1012. The majority of proteins have a secondary structure, although not always throughout the entire polypeptide chain. Polypeptide chains with a certain secondary structure can be arranged differently in space. This spatial arrangement is called the tertiary structure. In the formation of the tertiary structure, in addition to hydrogen bonds, ionic and hydrophobic interactions play an important role. According to the nature of the "packaging" of the protein molecule, globular, or spherical, and fibrillar, or filamentous, proteins are distinguished. In some cases, individual protein subunits form complex ensembles with the help of hydrogen bonds, electrostatic and other interactions. In this case, a quaternary structure of proteins is formed. However, it should be noted once again that the primary structure plays an exceptional role in the organization of higher protein structures. The structure of a protein molecule Characteristics of the structure Primary - linear The order of alternation of amino acids in the polypeptide chain - linear structure The type of bond that determines the structure Graphic image Peptide bond NH CO Secondary - helical Twisting of the polypeptide linear chain into a helix - helical structure Intramolecular HYDROGEN BONDS Tertiary - globular Packing of the secondary helix into tangle - glomerular structure Disulfide and ionic bonds CO ... HNCO ... HN There are several classifications of proteins. They are based on different features: Degree of complexity (simple and complex); The shape of the molecules (globular and fibrillar proteins); Solubility in individual solvents (water-soluble, soluble in dilute saline solutions - albumins, alcohol-soluble - prolamins, soluble in dilute alkalis and acids - glutelins); executable skeletal, etc.). function (for example, storage proteins, Proteins are amphoteric electrolytes. At a certain pH value of the medium (it is called the isoelectric point), the number of positive and negative charges in the protein molecule is the same. This is one of the properties of the protein. Proteins at this point are electrically neutral, and their solubility in water The ability of proteins to reduce solubility when their molecules become electrically neutral is used to isolate them from solutions, for example, in the technology of obtaining protein products.The process of hydration means the binding of water by proteins, while they exhibit hydrophilic properties: they swell, their mass and volume increase.Swelling of the protein is accompanied by its partial dissolution.The hydrophilicity of individual proteins depends on their structure.The hydrophilic amide (CO-NH-, peptide bond), amine (NH2) and carboxyl (COOH) groups present in the composition and located on the surface of the protein macromolecule attract water molecules, strictly orienting them on the surface of molecules uly. The hydration (water) shell surrounding the protein globules prevents aggregation and sedimentation, and therefore contributes to the stability of the protein solution. With limited swelling, concentrated protein solutions form complex systems called jelly. The jellies are not fluid, elastic, have plasticity, a certain mechanical strength, and are able to maintain their shape. Globular proteins can be completely hydrated by dissolving in water (for example, milk proteins), forming solutions with a low concentration. The hydrophilicity of grain and flour proteins plays an important role in the storage and processing of grain, in baking. The dough, which is obtained in the baking industry, is a protein swollen in water, a concentrated jelly containing starch grains. During denaturation, under the influence of external factors (temperature, mechanical action, the action of chemical agents, and a number of other factors), a change occurs in the secondary, tertiary, and quaternary structures of the protein macromolecule, i.e., its native spatial structure. Primary structure, and therefore. And the chemical composition of the protein does not change. Physical properties change: solubility decreases, ability to hydrate, biological activity is lost. The shape of the protein macromolecule changes, aggregation occurs. At the same time, the activity of some chemical groups increases, the effect of proteolytic enzymes on proteins is facilitated, and therefore it is easier to hydrolyze. In food technology, thermal denaturation of proteins is of particular practical importance, the degree of which depends on temperature, duration of heating and humidity. Protein denaturation can also be caused by mechanical action (pressure, rubbing, shaking, ultrasound). Finally, the action of chemical reagents (acids, alkalis, alcohol, acetone) leads to the denaturation of proteins. All these methods are widely used in the food industry and biotechnology. The foaming process is understood as the ability of proteins to form highly concentrated liquid-gas systems called foams. Foam stability , in which the protein is a foaming agent, depends not only on its nature and concentration, but also on temperature.Proteins are used as foaming agents in the confectionery industry (marshmallow, marshmallow, soufflé).Bread has a foam structure, and this affects its taste properties For the food industry, two very important processes can be distinguished: 1) Hydrolysis of proteins under the action of enzymes; 2) Interaction of amino groups of proteins or amino acids with carbonyl groups of reducing sugars. The rate of protein hydrolysis depends on its composition, molecular structure, enzyme activity, and conditions. The hydrolysis reaction with the formation of amino acids can be generally written as follows: Proteins burn to form nitrogen, carbon dioxide and water, as well as some other substances. Burning is accompanied by the characteristic smell of burnt feathers. The following reactions are used: xantoprotein, in which aromatic and heteroatomic cycles interact in a protein molecule with concentrated nitric acid, accompanied by the appearance of a yellow color; biuret, in which weakly alkaline solutions of proteins interact with a solution of copper (II) sulfate with the formation of complex compounds between Cu2+ ions and polypeptides. The reaction is accompanied by the appearance of a violet-blue color.

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Slides captions:

Squirrels Completed by: Teacher of chemistry and biology of the Moscow State Educational Institution "Silver Key School" Shkitina O.V. year 2012

Amino acid - an organic compound containing: 1) carboxyl (- C OOH) 2) amine (- NH 2) groups. 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 synthesis

Proteins (proteins, polypeptides) are high-molecular organic substances consisting of amino acids linked in a chain by a peptide bond. protein molecule

PROTEIN STRUCTURE

CHEMICAL PROPERTIES OF PROTEINS alcohol Tertiary structure Primary structure DENATURATION - destruction of secondary and tertiary structures under the influence of various environmental factors.

Factors causing denaturation Alcohol High temperature Heavy metal salts

“Salting out” of proteins with sodium chloride solution is a reversible process

The hydrolysis of proteins leads to the breaking of peptide bonds and the formation of amino acid molecules. The combustion of proteins proceeds with the formation

Color reactions of proteins Biuret reaction When a copper (II) hydroxide solution is added to a protein solution, a red-violet precipitate precipitates

When concentrated nitric acid is added to the protein solution and then heated, a bright yellow precipitate is formed Xantoprotein reaction

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Antoine Francois de Fourcroix. Proteins were brought into a separate class of biological molecules in the 18th century as a result of the work of the French chemist Antoine Fourcroix and other scientists, in which the property of proteins to coagulate (denature) under the influence of heat or acids was noted. At that time, such proteins as albumin, fibrin, gluten were investigated.

Proteins - protein substances, Proteins, or protein substances, are called high-molecular (molecular weight varies from 5-10 thousand to 1 million or more) natural polymers, the molecules of which are built from amino acid residues connected by a peptide bond.

Proteins differ in their degree of solubility in water, but most proteins dissolve in it. Insoluble ones include, for example, keratin (the protein that makes up hair, mammalian hair, bird feathers, etc.) and fibroin, which is part of silk and cobwebs. Proteins are also divided into hydrophilic and hydrophobic. Hydrophilic include most of the proteins of the cytoplasm, nucleus and intercellular substance, including insoluble keratin and fibroin. Hydrophobic include most of the proteins that make up the biological membranes of integral membrane proteins that interact with hydrophobic membrane lipids (these proteins usually also have small hydrophilic regions).

Gerrit Mulder Dutch chemist Gerrit Mulder analyzed the composition of proteins and hypothesized that almost all proteins have a similar empirical formula. Mulder also determined the degradation products of the amino acid proteins and for one of them (leucine) with a small margin of error determined the molecular weight of 131 daltons. In 1836 Mulder proposed the first model of the chemical structure of proteins. Based on the theory of radicals, he formulated the concept of the minimum structural unit of protein composition, C16H24N4O5, which was called "protein", and the theory "protein theory".

Emil Fischer 1) At the beginning of the 20th century, the German chemist Emil Fischer experimentally proved that proteins consist of amino acid residues connected by peptide bonds. He also carried out the first analysis of the amino acid sequence of a protein and explained the phenomenon of proteolysis.

Proteins are the basis of biomembranes, the most important part of the cell and cellular components. They play a key role in the life of the cell, leaving, as it were, the material basis of its chemical activity. 2) The most important component of human and animal food, the supplier of the amino acids they need 3) Self-organization of the structure, i.e. its ability to spontaneously create a specific spatial structure peculiar only to a given protein. Essentially, all the activities of the body (development, movement, performance of various functions, and much more) are associated with protein substances. It is impossible to imagine life without proteins.

James Sumner 1) However, the central role of proteins in organisms was not recognized until 1926, when the American chemist James Sumner (later Nobel Prize winner) showed that the urease enzyme is a protein 2) The difficulty of isolating pure proteins made their study difficult. Therefore, the first studies were carried out using those polypeptides that could be purified in large quantities, i.e. blood proteins, chicken eggs, various toxins, and digestive/metabolic enzymes released after slaughter.

An important role in creating the structure of proteins is played by ionic (salt) and hydrogen bonds, as well as hydrophobic interaction - a special type of contact between the hydrophobic components of protein molecules in an aqueous medium. All these bonds have different strengths and provide the formation of a complex, large protein molecule. Despite the difference in the structure and functions of protein substances, their elemental composition fluctuates slightly (in % of dry mass): carbon-51-53; oxygen-21.5-23.5; nitrogen-16.8-18.4; hydrogen-6.5-7.3; sulfur-0.3-2.5

Linus Pauling Linus Pauling is credited with being the first scientist to successfully predict the secondary structure of proteins. William Astbury The idea that the secondary structure of proteins is the result of the formation of hydrogen bonds between amino acids was proposed by William Astbury in 1933, Walter Kauzman, Kaya Linderström-Langa formation of the tertiary structure of proteins and the role of hydrophobic interactions in this process.

Peptide bond Structure of a protein molecule Structural characteristic Type of bond that determines the structure Graphic image Primary - linear Order of alternation of amino acids in the polypeptide chain - linear structure Secondary - helical Twisting of the polypeptide linear chain into a spiral - helical structure Intramolecular HYDROGEN BONDS Tertiary - globular Packing of the secondary helix into a ball - glomerular structure Disulfide and ionic bonds

The primary structure of a protein. The sequence of amino acid residues in the polypeptide chain is called the primary structure of the protein. The total number of different types of proteins in all types of living organisms is Secondary structure Most proteins have a secondary structure, although not always throughout the entire polypeptide chain.

Polypeptide chains with a certain secondary structure can be arranged differently in space. This spatial arrangement is called the tertiary structure. In the formation of the tertiary structure, in addition to hydrogen bonds, ionic and hydrophobic interactions play an important role. According to the nature of the "packaging" of the protein molecule, globular, or spherical, and fibrillar, or filamentous, proteins are distinguished.

There are several classifications of proteins. They are based on different features: Degree of complexity (simple and complex); The shape of the molecules (globular and fibrillar proteins); Solubility in individual solvents (water-soluble, soluble in dilute saline solutions - albumins, alcohol-soluble - prolamins, soluble in dilute alkalis and acids - glutelins); Function performed (eg, storage proteins, skeletal, etc.).

During denaturation, under the influence of external factors (temperature, mechanical action, the action of chemical agents, and a number of other factors), a change occurs in the secondary, tertiary, and quaternary structures of the protein macromolecule, i.e., its native spatial structure. The primary structure and, consequently, the chemical composition of the protein do not change. Physical properties change: solubility decreases, ability to hydrate, biological activity is lost. The shape of the protein macromolecule changes, aggregation occurs. At the same time, the activity of some chemical groups increases, the effect of proteolytic enzymes on proteins is facilitated, and therefore proteins are more easily hydrolyzed. In food technology, thermal denaturation of proteins is of particular practical importance, the degree of which depends on temperature, duration of heating and humidity. Protein denaturation can also be caused by mechanical action (pressure, rubbing, shaking, ultrasound). Finally, the action of chemical reagents (acids, alkalis, alcohol, acetone) leads to the denaturation of proteins. All these techniques are widely used in the food industry and biotechnology.

The process of hydration means the binding of water by proteins, while they exhibit hydrophilic properties: they swell, their mass and volume increase. Swelling of the protein is accompanied by its partial dissolution. The hydrophilicity of individual proteins depends on their structure. The hydrophilic amide (CO-NH-, peptide bond), amine (NH 2) and carboxyl (COOH) groups present in the composition and located on the surface of the protein macromolecule attract water molecules, strictly orienting them on the surface of the molecule. The hydration (water) shell surrounding the protein globules prevents aggregation and sedimentation, and therefore contributes to the stability of the protein solution. With limited swelling, concentrated protein solutions form complex systems called jelly. The jellies are not fluid, elastic, have plasticity, a certain mechanical strength, and are able to maintain their shape. Globular proteins can be completely hydrated by dissolving in water (for example, milk proteins), forming solutions with a low concentration. The hydrophilicity of grain and flour proteins plays an important role in the storage and processing of grain, in baking. The dough, which is obtained in the baking industry, is a protein swollen in water, a concentrated jelly containing starch grains.

Proteins burn with the formation of nitrogen, carbon dioxide and water, as well as some other substances. Burning is accompanied by the characteristic smell of burnt feathers. The following reactions are used: xantoprotein, in which aromatic and heteroatomic cycles interact in a protein molecule with concentrated nitric acid, accompanied by the appearance of a yellow color; biuret, in which weakly alkaline solutions of proteins interact with a solution of copper (II) sulfate with the formation of complex compounds between Cu 2+ ions and polypeptides. The reaction is accompanied by the appearance of a violet-blue color.

2) Biuret reaction for a peptide bond Progress of work Place 5 drops of a diluted protein solution in a test tube, add 3 drops of a 10% NaOH solution and 1 drop of a 1% CuS0 4 solution. Mix everything. Observations A blue-violet color appears. Equations: 1. Preparation of undiluted hen egg white Separate the white of three hen eggs from the yolks. Considering that the average mass of protein in one egg is 33 g (yolk 19 g), approximately 100 ml of undiluted chicken egg protein is obtained. It contains 88% water, 1% hydrocarbons and 0.5% minerals, the rest is protein. Thus, undiluted chicken egg protein was obtained, which is a 10% protein solution. 2. Preparation of a dilute solution of egg albumin Separate the protein of one chicken egg from the yolk, beat it well and then mix it in a flask with shaking with 10 times the volume of distilled water. The solution is filtered through a double layer of gauze moistened with water. The filtrate contains the ovalbumin solution and the oval globulin remains in the sediment. Get a 0.5% solution of egg albumin. Conclusion: a qualitative biuret reaction for a peptide bond in a protein. It is based on the ability of a peptide bond to form colored complex compounds with CuSO 4 in an alkaline medium. PROTEIN SOLUTION PREPARATION FOR QUALITATIVE REACTIONS.

3. Xantoprotein reaction Procedure Add 3 drops of concentrated HNO 3 to 5 drops of diluted egg white solution and heat gently. After cooling (do not shake!) add 5-10 drops of 10% NaOH solution until color appears. Observations After heating, the color of the solution becomes pale yellow, and after cooling and adding NaOH solution, it becomes yellow-orange. Equation: Conclusion: xantoprotein reaction makes it possible to detect amino acids in a protein that contain a benzene ring (tryptophan, phenylalanine, tyrosine). 4. Adamkiewicz reaction Proceedings of work 5 drops of undiluted protein and 2 ml of ice-cold CH 3 COOH are placed in a test tube. Heat gently until the precipitate formed dissolves. Cool the tube with the mixture. Carefully pour 1 ml of concentrated H 2 S0 4 along the wall of the test tube so that the liquids do not mix. Observations When acetic acid is added to a test tube, a precipitate is formed, which dissolves when heated. When concentrated sulfuric acid is added to a test tube, a red-violet ring appears at the boundary of two liquids. Equations: Conclusion: the Adamkevich reaction is qualitative for tryptophan, since the latter in an acidic environment interacts with glyoxylic acid, which is present in CH 3 COOH as an impurity. 5. Reaction with picric acid Progress of work Add to 10 drops of a dilute protein solution several crystals of Na 2 C0 3 and 5 drops of a saturated aqueous solution of picric acid, mix and heat in a spirit lamp flame until the yellow color of the solution changes to red. Observations After adding picric acid, the solution turns yellow, and after heating, the color changes to red. Equation: Conclusion: the reaction with picric acid makes it possible to detect compounds with reducing ability (based on the reduction of picric acid to picramic acid due to diketopiperazine groups). 6. Fohl reaction Progress of work Add to 10 drops of undiluted protein 20 drops of a 30% NaOH solution, a few drops of (CH 3 COO) 2 Pb and boil the mixture (carefully: the liquid is thrown out!). Ammonia released is detected with wet litmus paper. Observations The undiluted protein gives an orange color with NaOH, when (CH 3 COO) 2 Pb is added and heated, it turns black. Litmus turns blue.