Biochemical components. Biochemical basis of human nutrition
The body of living beings consists not just of molecules and atoms, but of a collection of elements that allow it to carry out all life processes harmoniously and harmoniously. It is thanks to structures such as biogenic elements that humans, plants, animals, fungi and bacteria can move, breathe, eat, reproduce and generally live. They all have their cells in common chemical system Mendeleev.
Biogenic elements - what are they?
In general, it should be noted that of the 118 known elements today, the exact role and significance in the body of living beings has been determined for relatively few. Although experimental data have made it possible to establish that each human cell contains approximately 50 chemical elements. It is they who are called biogenic, or biophilic.
Of course, most of them have been carefully studied, all options for their influence on human health and condition (both in excess and in deficiency) have been considered. However, a certain proportion of substances remain, the role of which is not fully understood. This remains to be determined.
Classification of biophilic elements
Biogenic elements can be divided into three groups according to their quantitative content and significance for living systems.
- Macrobiogenic - those from which all vital compounds are built: proteins, nucleic acids, carbohydrates, lipids and others. These are the main biogenic elements, including carbon, hydrogen, oxygen, sulfur, sodium, chlorine, magnesium, calcium, phosphorus, nitrogen, and potassium. Their content in the body is maximum in relation to others.
- Microbiogenic - contained in smaller quantities, but playing a very important role in maintaining a normal level of vital activity, carrying out many processes and maintaining health. This group includes manganese, selenium, fluorine, vanadium, iron, zinc, iodine, ruthenium, nickel, chromium, copper, germanium.
- Ultramicrobiogenic. What role these biogenic chemical elements play in the body has not yet been clarified. However, it is believed that they are also important and must be maintained in constant balance.
This classification of nutrients reflects the importance of a particular substance. However, there is another one, which divides all compounds present in the body into metals and non-metals. The table of chemical elements is reflected in living systems, which once again emphasizes how interconnected everything is.
Characteristics and importance of macroelements
If you understand the structure of protein molecules, it is easy to understand how important the biogenic elements of the macronutrient group are. After all, they include:
- carbon;
- oxygen;
- hydrogen;
- nitrogen;
- sometimes sulfur.
That is, all of the listed substances that we have named are vital. This is quite justified, because it is not for nothing that proteins are called the basis of life.
The chemistry of nutrients plays an important role in this. After all, for example, it is precisely thanks to the chemical properties of carbon that it is able to combine with atoms of the same name, forming huge macrochains - the basis of all organic compounds, and therefore of life. If it were not for the ability of hydrogen to form hydrogen bonds between molecules, it is unlikely that proteins and nucleic acids could exist. Without them there would be no living beings.
Oxygen is one of the the most important elements not only is it part of the most important substance on the planet - water, but also has strong electronegativity. This allows it to take part in many interactions, including the formation of hydrogen bonds.
There is probably no need to talk about the importance of water. Every child knows about its importance. It is a solvent, a medium for biochemical reactions, the main component of the cytoplasm of cells, and so on. Its biogenic elements are the same hydrogen and oxygen, which were already mentioned earlier.
Element No. 20 in the table
Calcium is found in human and animal bones and is an important component of tooth enamel. It also takes part in many biological processes inside the body:
- exocytosis;
- blood clotting;
- contraction of muscle fibers;
- hormone production.
In addition, it forms the exoskeleton of many invertebrates and marine life. The need for this element increases with age, and after reaching 20 years of age it decreases.
The value of sodium and potassium
These two elements are very important for the correct and coordinated functioning of cell membranes, as well as the sodium-potassium pump of the heart. Many drugs for diseases of the cardiovascular system contain these substances. In addition, these same elements:
- maintain osmotic pressure in the cell;
- regulate the pH of the environment;
- are part of blood plasma and lymphatic fluids;
- retain water in tissues;
- contribute to the transmission of nerve impulses and so on.
The processes are vital, so it is difficult to overestimate the importance of these macroelements.
Magnesium and phosphorus
The table of chemical elements placed these two substances quite far apart due to the difference in properties, both physical and chemical. The biological role also varies, but they also have something in common - their importance in the life of living beings.
Magnesium performs the following functions:
- takes part in the splitting of macromolecules, which is accompanied by the release of energy;
- participates in the transmission of nerve impulses and in the regulation of cardiac activity;
- is active component For normal operation intestines;
- is part of the substances that control the activity of smooth muscles, and so on.
These are not all the functions, but the main ones.
Phosphorus, in turn, plays the following role:
- is part of a large number of macromolecules (phospholipids, enzymes and others);
- is a component of the body’s most important energy reserves - ATP and ADP molecules;
- controls the pH of solutions, acts as a buffer in the body;
- is part of bones and teeth as one of the main building elements.
Thus, macroelements are an important part of the health of humans and other creatures, their basis, the beginning of all life on the planet.
Main features of microelements
Biogenic elements that belong to this group differ in that the body’s need for them is less than for representatives of the previous group. Approximately 100 mg per day, but not more than 150 mg. In total there are about 30 varieties. Moreover, they are all found in different concentrations in the cell.
The role of not all of them has been established, but the consequences of insufficient consumption of one or another element are clearly manifested, expressed in various diseases. The most studied for their biological effects on the body are copper, selenium and zinc, as well as iron. All of them take part in the mechanisms of humoral regulation, are part of enzymes, and are catalysts for processes.
Biophilic particle cycling: carbon
Each atom is capable of making a transition from an organism to environment and back. In this case, a process called the “cycle of nutrients” occurs. Let's consider its essence using the example of the carbon atom.
Atoms go through several stages in their cycle.
- The bulk is found in the bowels of the earth in the form of coal, as well as in the air, forming a layer of carbon dioxide.
- Carbon passes from the air into plants as it is absorbed by them for photosynthesis.
- Then it either remains in plants until they die and passes into coal deposits, or passes into animal organisms that feed on plants. Of these, carbon is returned to the atmosphere in the form of carbon dioxide.
- If we talk about that carbon dioxide, which is dissolved in the World Ocean, then from the water it enters plant tissue, eventually forming limestone deposits, or it evaporates into the atmosphere and the previous cycle begins again.
Thus, biogenic migration of chemical elements, both macro- and microbiogenic, occurs.
Biochemical role and medical and biological significance of biogenic p-elements. (carbon, nitrogen, phosphorus, oxygen, sulfur, chlorine, bromine, iodine)
Biogenic d-elements. Relationship between the electronic structure of d-elements and their biological functions. The role of d-elements in complex formation in biological systems.
More than 70 elements have been found in living matter.
Nutrients- elements necessary for the body to build and function cells and organs.
The human body contains the most s- and p-elements.
Essential macroelements s-: H, Na, Mg, K, Ca
Essential macroelements p-: C, N, O, P, S, Cl, I.
Impurity s- and p-elements: Li, B, F.
Concentration of a chemical element– increased content of the element in the body compared to the environment.
The basis of all living systems is made up of six organogenic elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur. Their content in the body reaches 97%.
Biogenic elements are divided into three blocks: s-, p-, d-.
S-elements
Basic information:
1. S-elements are chemical elements whose atoms are filled with electrons, the s-sublevel of the outer level.
2. The structure of their valence level ns 1-2.
3. Small nuclear charge, big size atoms contribute to the fact that the atoms of s-elements are typical active metals; an indicator of this is their low ionization potential. The chemistry of such elements is mainly ionic, with the exception of lithium and beryllium, which have a stronger polarizing effect.
4. They have relatively large radii of atoms and ions.
5. Easily donate valence electrons.
6. They are strong reducing agents. The reducing properties increase naturally with increasing atomic radius. Regenerative capacity increases across the group from top to bottom.
Biological role:
Due to their very easy oxidation, alkali metals occur in nature exclusively in the form of compounds.
Sodium
1. Refers to vital elements, is constantly contained in the body, and participates in metabolism.
3. In the human body, sodium is found in the form of soluble salts: chloride, phosphate, bicarbonate.
4. Distributed throughout the body (in the blood serum, in the cerebrospinal fluid, in the eye fluid, in digestive juices, in bile, in the kidneys, in the skin, in bone tissue, in the lungs, in the brain).
5. Is the main extracellular ion.
6. Sodium ions play an important role in ensuring the constancy of the internal environment of the human body and participates in maintaining a constant osmotic pressure of the biofluid.
7. Sodium ions are involved in the regulation of water metabolism and affect the functioning of enzymes.
8. Together with potassium, magnesium, calcium, and chlorine ions, sodium ions participate in the transmission of nerve impulses.
9. When sodium content changes in the body, disorders of the nervous, cardiovascular systems, smooth and skeletal muscles occur.
Potassium
2. In the human body, potassium is found in the blood, kidneys, heart, bone tissue, and brain.
3. Potassium is the main intracellular ion.
4. Potassium ions play an important role in physiological processes - muscle contraction, normal functioning heart, conduction of nerve impulses, metabolic reactions.
5. They are important activators of intracellular enzymes.
Magnesium
2. Located in dentin and enamel of teeth, bone tissue.
3. Accumulates in the pancreas, skeletal muscles, kidneys, brain, liver and heart.
4. Is an intracellular cation.
Calcium
2. Contained in every cell of the human body. The bulk is in bone and dental tissues.
3. Calcium ions take an active part in the transmission of nerve impulses, muscle contraction, regulation of the heart muscle, and blood clotting mechanisms.
P-elements
General characteristics:
1. List 30 elements of the periodic table.
2. In periods from left to right, the atomic and ionic radii of p-elements decrease as the nuclear charge increases, the ionization energy and electron affinity generally increase, the electronegativity increases, the oxidative activity of elemental substances and non-metallic properties increase.
3. In groups, the radii of atoms and ions of the same type increase. The ionization energy decreases when moving from 2p elements.
4. With an increase in the ordinal number of p-elements in a group, non-metallic properties weaken and metallic properties increase.
Biological role:
2. Concentrated in the lungs, thyroid gland, spleen, liver, brain, kidneys, heart.
3. Part of teeth and bones.
4. Excess boron is harmful to the human body (adrenaline activity decreases).
Aluminum
1. Refers to impurity elements.
2. Concentrated in blood serum, lungs, liver, bones, kidneys, nails, hair, and is part of the structure of the nerve membranes of the human brain.
3. Daily norm – 47 mg.
4. Affects the development of epithelial and connective tissues, the regeneration of bone tissue, and phosphorus metabolism.
5. Affects enzymatic processes.
6. Excess inhibits hemoglobin synthesis.
Thallium
1. Refers to very toxic elements.
Carbon
1. Refers to macroelements.
2. Included in the composition of all tissues in the form of proteins, fats, carbons, vitamins, hormones.
3. From a biological point of view, carbon is the number 1 organogen.
Silicon
1. Refers to impurity microelements.
2. Located in the liver and adrenal glands. Hair, lens.
3. Violation of silicon is associated with the occurrence of hypertension, rheumatism, ulcers, and anemia.
Germanium
1. Refers to microelements.
2. Germanium compounds enhance hematopoiesis in the bone marrow.
3. Germanium compounds are low toxic.
D-elements
General characteristics:
1. There are 32 elements of the periodic table.
2. Enters 4-7 major periods. A feature of the elements of these periods is a disproportionately slow increase in atomic radius with increasing number of electrons.
3. Important property is the variable valence and variety of oxidation states. The possibility of the existence of d-elements in different oxidation states determines a wide range of redox properties of the elements.
4. D-elements in intermediate oxidation states exhibit amphoteric properties.
5. The body ensures the launch of most biochemical processes that ensure normal life.
Biological role:
Zinc
1. Microelement
2. In the human body 1.8 g.
3. Most zinc is found in muscles and bones, as well as in blood plasma, liver, and red blood cells.
4. Forms a bioinorganic complex with insulin, a hormone that regulates blood sugar.
5. Contained in meat and dairy products, eggs.
Cadmium
1. Microelement.
2. In the human body – 50 mg.
3. Impurity element.
4. Found in the kidneys, liver, lungs, pancreas.
Mercury
1. Microelement.
2. Impurity element.
3. In the human body – 13 mg.
4. Found in fatty and muscle tissues.
5. Chronic cadmium and mercury intoxication can impair bone mineralization.
Chromium
1. Microelement.
2. In the human body – 6g.
3. Chromium metal is non-toxic and the compounds are hazardous to health. They cause skin irritation, which leads to dermatitis.
Molybdenum
1. Microelement.
2. Refers to the metals of life and is one of the most important bioelements.
3. Excessive content causes a decrease in bone strength - osteoporosis.
4. Contains various enzymes.
5. Low toxicity.
Tungsten
1. Microelement.
2. The role has not been studied.
3. The anionic form of tungsten is easily absorbed in the gastrointestinal tract.
Task 5
Complex connections. Classification of complex compounds according to the charge of the coordination sphere and the nature of the ligands. 2. Coordination theory of A. Werner. The concept of complexing agents and ligands. 3. Coordination number, its relationship with the geometry of the complex ion. The nature of the connection in coordination compounds. Biological complex glands, cobalt, copper, zinc, their role in life processes.
Complex connections– chemical compounds whose crystal lattices consist of complex groups formed as a result of the interaction of ions or molecules that can exist independently.
Classification of KS according to the charge of the inner sphere:
1. Cationic Cl 2
2. Anionic K 2
3. Neutral
Classification of KS by the number of places occupied by ligands in the coordination sphere:
1. Monodentate ligands. They take 1st place in the coordination area. Such linands are neutral (molecules H 2 O, NH 3, CO, NO) and charged (ions CN -, F -, Cl -, OH -,).
2. Bidentate ligands. Examples are ligands: aminoacetic acid ion, SO 4 2-, CO 3 2-.
3. Polydentate ligands. 2 or more bonds with ions. Examples: ethylene diamine tetraacetic acid and e salts, proteins, nucleic acid.
Classification by nature of the ligand:
1. Ammonia– complexes in which ammonia molecules serve as ligands. SO 4.
2. Aqua complexes– in which water is the ligand. Cl2
3. Carbonyls– in which the ligands are carbon monoxide molecules (II). ,
4. Hydroxo complexes– in which godroxide ions act as ligands. Na2.
5. Acid complexes– in which the ligands are acidic residues. These include complex salts and complex acids K2, H2.
Werner's theory:
· Explanations of the structural features of complex compounds
· According to this theory, every complex compound has a central atom (ion), or complexing agent (central atom or central ion).
· Around the central atom there are other ions, atoms or molecules, which are called ligands (addends), located in a certain order.
Complexing agent– the central atom of a complex particle. Typically the complexing agent is an atom of the element that forms the metal, but it can also be an atom of oxygen, nitrogen, sulfur, iodine, and other elements that form nonmetals. The complexing agent is usually positively charged, and in this case is called a metal center. The charge of the complexing agent can also be negative or equal to zero.
Ligands (Addens)– atoms or isolated groups of atoms located around the complexing agent. Ligands can be particles that, before the complex compound was formed, were molecules (H 2 O, CO, NH 3), anions (OH -, Cl -, PO 4 3-), as well as the hydrogen cation H +.
The central atom (central ion), or complexing agent, is linked by ligands by a polar covalent bond via a donor-acceptor mechanism and forms the inner sphere of the complex.
Coordination number– the number of ligands coordinated around the central atom – the complexing agent.
Coordination number of the central atom– the number of bonds through which the ligands are directly connected to the central atom.
A certain pattern is observed between the coordination number and the structure of complex compounds (the geometry of the internal coordination sphere).
· If the complexing agent has coordination number 2, as a rule, a complex ion has linear structure, and the complexing agent and the ligand are located on the same straight line. Such complex ions as others +, – and others have a linear structure. In this case, the orbitals of the central atom participating in the formation of bonds according to the donor-acceptor mechanism are sp hybridized.
· Complexes with coordination number 3 are relatively rare and usually have the form equilateral triangle, in the center of which there is a complexing agent, and in the corners there are ligands (hybridization of the sp 2 type).
· For connections with coordination number 4 There are two possibilities for the spatial arrangement of ligands. Tetrahedral placement ligands with a complexing agent in the center of the tetrahedron (sp 3 -hybridization of the atomic orbitals of the complexing agent). Flat-square arrangement ligands around the complexing atom located in the center of the square (dsp 2 hybridization).
· Coordination number 5 It is quite rare in complex compounds. However, in the small number of complex compounds where the complexing agent is surrounded by five ligands, two spatial configurations have been established. This trinal bipyramid And square pyramid with a complex-former in the center of a geometric figure.
· For complexes with coordination number 6 typical octahedral arrangement ligands, which corresponds to sp 3 d 2 - or d 2 sp 3 -hybridization of the atomic orbitals of the complexing agent. The octahedral structure of complexes with a coordination number of 6 is the most energetically favorable.
Biological role:
· Fe 3+ - is part of the enzymes that catalyze ORR
· Co – vitamin B12 (hematopoiesis and synthesis nucleic acid)
Mg 2+ - chlorophyll (sun energy reserve; synthesis of polysaccharides)
· Mo – purine metabolism.
Task 6
Basic provisions of the theory of solutions: solution, solvent, solute. Classification of solutions. 2. Factors determining solubility. 3. Methods of expressing the concentration of solutions, mass fraction, molarity, molar concentration of equivalents. Law of equivalents. 4. Solutions gaseous substances: laws of Henry, Dalton. Solubility of gases in the presence of electrolytes - Sechenov's law. The role of the solution in the life of the body.
Solution– a homogeneous mixture consisting of particles of a dissolved substance, a solvent and products from the interaction. Solvent– a component whose state of aggregation does not change during the formation of a solution. The mass of the solvent predominates.
Classification By state of aggregation :
1. Solid (steel alloy)
2. Liquid (a solution of salt or sugar in water)
3. Gaseous (atmosphere).
Also distinguished:
· Aqueous and non-aqueous solutions.
· Diluted and undiluted solutions.
· Saturated and unsaturated.
Factors determining solubility:
1. The nature of the substances being mixed (like dissolves in like)
2. Temperature
3. Pressure
4. Presence of a third component
There are many ways to measure the amount of substance found in a unit volume or mass of a solution, these are the so-called ways to express concentration solution.
Quantitative concentration expressed in terms of molar, normal (molar concentration equivalent), percentage, molal concentration, titer and mole fraction.
1. The most common way to express the concentration of solutions is molar concentration of solutions or molarity. It is defined as the number of moles of solute in one liter of solution. C m = n/V, mol/l (mol l -1)
2. Molar concentration equivalent determined by the number molar masses equivalents per 1 liter of solution.
3. Percentage concentration of solution or mass fraction shows how many units of mass of solute are contained in 100 units of mass of solution. This is the ratio of the mass of a substance to the total mass of a solution or mixture of substances. The mass fraction is expressed in fractions of a unit or as a percentage.
4. Molar concentration solution shows the number of moles of solute in 1 kg of solvent.
5. Solution titer shows the mass of solute contained in 1 ml of solution.
6. Mole or mole fraction of a substance in a solution is equal to the ratio of the amount of a given substance to the total amount of all substances contained in the solution.
EXAM QUESTIONS IN BIOLOGICAL CHEMISTRY
for dental students
1. Subject and tasks of biological chemistry. Metabolism and energy, hierarchical structure of organization and self-reproduction as the most important signs of living matter.
2. The place of biochemistry among other biological disciplines. Levels of structural organization of living things. Biochemistry as the molecular level of studying life phenomena. Biochemistry and medicine.
3. The study of the biochemical patterns of formation of parts of the dentofacial apparatus and maintaining their functionality is the fundamental basis of a complex of dental disciplines.
4. Protein molecules are the basis of life. Elementary composition of proteins. Discovery of amino acids. Peptide theory of protein structure.
5. Structure and classification of amino acids. Their physicochemical properties. Methods for separating proteins by physical and chemical properties.
6. Molecular weight of proteins. Sizes and shapes of protein molecules. Globular and fibrillar proteins. Simple and complex proteins.
7. Physico-chemical properties of proteins: solubility, ionization, hydration, precipitation of proteins from solutions. Denaturation. Methods for quantitative measurement of protein concentration.
8. Primary structure of proteins. Dependence of biological properties on the primary structure. Species specificity of the primary structure of proteins.
9. Conformation of peptide chains (secondary and tertiary structure). Bonds that ensure protein conformation. Dependence of biological properties on conformation.
10. Domain organization of protein molecules. Separation of proteins into families and superfamilies.
11. Quaternary structure of proteins. Dependence of the biological activity of proteins on the quaternary structure. Cooperative changes in the conformation of protomers (using the example of hemoglobin).
12. Conformational changes in proteins as the basis for the functioning and self-regulation of proteins.
13. Native proteins. Factors of denaturation and its mechanism.
14. Classification of proteins by chemical composition. a brief description of group of simple proteins.
15. Complex proteins: definition, classification by non-protein component. Brief description of representatives.
16. Biological functions of proteins. The ability for specific interactions (“recognition”) as the basis of the biological functions of all proteins. Types of natural ligands and features of their interaction with proteins.
17. Differences in the protein composition of organs and tissues. Changes in protein composition during ontogenesis and diseases.
18. Enzymes, history of discovery. Features of enzymatic catalysis. Specificity of enzyme action. Classification and nomenclature of enzymes.
19. Structure of enzymes. The active center of enzymes, theories of its formation.
20. Main stages of enzymatic catalysis (mechanism of action of enzymes).
21. Dependence of the rate of enzymatic reactions on temperature, pH, concentration of enzymes and substrate.
22. Enzyme cofactors: metal ions and coenzymes. Coenzyme functions of vitamins (diagram).
23. Activation of enzymes (partial proteolysis, reduction of thiol groups, removal of inhibitors). The concept of activators, the mechanism of their action.
24. Enzyme inhibitors. Types of inhibition. Medications– enzyme inhibitors.
25. Regulation of enzyme action: allosteric inhibitors and activators, catalytic and regulatory centers. Regulation of enzyme activity by type feedback, through phosphorylation and dephosphorylation.
26. Differences in the enzyme composition of organs and tissues. Organ-specific enzymes. Changes in enzyme activity during development and disease.
27. Hereditary and acquired enzymopathies. Isoenzymes.
28. Vitamins. History of the discovery and study of vitamins. Functions of vitamins. Alimentary and secondary vitamin deficiencies and hypovitaminosis. Hypervitaminosis.
29. Vitamins of group D. Provitamins, structure, transformation into the active form, effect on metabolism and mineralization processes.
30. Vitamin A, chemical structure, role in metabolic processes. Manifestations of hypo- and hypervitaminosis.
31. Vitamin C, chemical structure, role in vital processes, daily requirement, effect on the metabolism of oral tissues, manifestations of deficiency.
32. Basic levels of metabolic regulation. Autocrine, paracrine and endocrine regulation.
33. Hormones, concept, general characteristics, chemical nature, biological role.
34. Hormonal regulation as a mechanism of intercellular and interorgan coordination of metabolism. Target cells and cellular hormone receptors.
35. The mechanism of transmission of a hormonal signal into a cell by hormones of the membrane method of reception. Secondary intermediaries.
36. The mechanism of transmission of hormonal signals to effector systems by hormones of the cytosolic method of reception.
37. Central regulation of the endocrine system. The role of liberins, statins, pituitary tropic hormones.
38. Insulin, structure, formation from proinsulin. Effect on the metabolism of carbohydrates, lipids, amino acids.
39. Structure, synthesis and metabolism of iodothyronines. Effect on metabolism. Hypo- and hyperthyroidism: mechanism of occurrence and consequences.
40. Hormones that regulate the metabolism of mineralized tissues (parathyrin, calcitonin, somatotropin), places of production, chemical nature, mechanism of regulatory action.
41. Eicosanoids: concept, chemical structure, representatives. The role of eicosanoids in the regulation of metabolism and physiological functions of the body.
42. Low molecular weight proteins of intercellular communication (growth factors and other cytokines) and their cellular receptors.
43. Catabolism and anabolism. Endergonic and exergonic reactions in a living cell. Macroergic compounds. Dehydrogenation of substrates and oxidation of hydrogen (formation of water) as an energy source for ATP synthesis.
44. NAD-dependent and flavin dehydrogenases, ubiquinone dehydrogenase, cytochromes b, c, c 1, a 1 and a 3 as components of the respiratory chain.
45. The structure of mitochondria and the structural organization of the respiratory chain. Transmembrane electrochemical potential as an intermediate form of energy during oxidative phosphorylation.
46. The respiratory chain as the most important red-ox system of the body. Coupling of oxidation and phosphorylation processes in the respiratory chain. R/O ratio.
47. Thermoregulatory function of tissue respiration.
48. Regulation of the respiratory chain. Dissociation of tissue respiration and oxidative phosphorylation. Dissociating agents.
49. Energy metabolism disorders: hypoxic conditions. Vitamins PP and B 2. Manifestation of vitamin deficiencies.
50. Basic catabolism nutrients, stages. The concept of specific and general pathways of catabolism.
51. Pyruvic acid, ways of its formation. Oxidative decarboxylation of pyruvic acid: sequence of reactions, structure of the pyruvate dehydrogenase complex.
52. Acetyl-CoA, pathways of formation and transformation in the body. The significance of these processes.
53. Tricarboxylic acid cycle: sequence of reactions, characteristics of enzymes. Relationship between common catabolic pathways and the electron and proton transport chain.
54. Allosteric mechanisms of regulation of the citrate cycle. Formation of CO 2 during tissue respiration. Anabolic functions of the TCA cycle. Vitamin B 1 and pantothenic acid, their biological role.
55. Food proteins. General diagram of sources and pathways of amino acid consumption in tissues. Endogenous and exogenous pool of amino acids.
56. Protein standards in nutrition. Nitrogen balance. Physiological minimum protein in food. High-quality composition food proteins.
57. Proteolysis of proteins. General characteristics and classification of digestive canal proteinases, substrate specificity. Absorption of amino acids.
58. Transamination, reaction mechanism, coenzyme function of vitamin B6. Specificity of aminotransferases. Biological role of transamination reactions.
59. Oxidative deamination of amino acids, reaction chemistry. Oxidases of D- and L-amino acids. Glutamate dehydrogenase.
60. Indirect deamination (trans-deamination) of amino acids. Biological significance of deamination reactions.
61. Decarboxylation of amino acids, chemistry. Biogenic amines. Origin, functions. Inactivation of biogenic amines.
62. Features of the metabolism of individual amino acids. Glycine and serine. The mechanism of their mutual transformations. The role of glycine in the processes of biosynthesis of biologically important compounds.
63. Transmethylation. Methionine and S-adenosylmethionine. Their role in biosynthetic and neutralization reactions.
64. THFA and synthesis of one-carbon groups, their use. Manifestation of B deficiency 9. Antivitamins folic acid. Sulfonamide drugs.
65. Features of the metabolism of phenylalanine and tyrosine, main pathways, functionally significant metabolites. Genetic defects in the metabolism of these amino acids.
66. End products of amino acid metabolism: ammonium salts and urea. The main sources and ways of neutralizing ammonia in the body.
67. The role of glutamate in the neutralization and transport of ammonia, proline synthesis. Formation and excretion of ammonium salts.
68. Biosynthesis of urea, sequence of reactions. Relationship between the ornithine cycle and the TCA cycle. Disturbances in the formation and excretion of urea. Hyperammonemia, uremia.
69. Nucleic acids, types, nucleotide composition, localization in the cell, biological role.
70. Structure and biological functions of mononucleotides.
71. Primary and secondary structure of DNA, placement in a chromosome. DNA biosynthesis. DNA polymerases. The concept of a replicative system. DNA damage and repair.
72. RNA, primary and secondary structure, types of RNA in the cell, functions of RNA. RNA biosynthesis, enzymes.
73. Nucleases of the digestive tract and tissues. Breakdown of purine nucleotides. Causes of hyperuricemia. Gout.
74. Concept of the biosynthesis of purine nucleotides. Origin of the "C" and "N" atoms in the purine core. Inosinic acid as a precursor to adenylic and guanylic acids.
75. Concept of the breakdown and biosynthesis of pyrimidine nucleotides.
76. Biosynthesis of proteins, modern ideas. The main components of the protein synthesizing system. Stages of biosynthesis.
77. Transfer RNA as an amino acid adapter. Biosynthesis of aminoacyl-tRNA. Substrate specificity of APCases. Isoacceptor tRNAs.
78. Structure of ribosomes. The sequence of events on the ribosome during the assembly of a polypeptide chain. Post-translational changes in proteins.
79. Regulation of protein biosynthesis. Concept of operon, regulation of biosynthesis at the transcription level.
80. Molecular mechanisms genetic variability. Molecular mutations, types, frequency.
81. Mechanisms of increasing the number and diversity of genes in the genome during evolution as a manifestation of differential gene activity.
82. Cellular differentiation. Changes in the protein composition of cells during differentiation (using the example of Hb synthesis during the development of an erythrocyte).
83. Protein polymorphism as a manifestation of genetic heterogeneity. Variants of Hb, Hp, enzymes, group-specific blood substances.
84. Hereditary diseases: prevalence, origin of defects in the genotype. The mechanism of occurrence and biochemical manifestations of hereditary diseases.
85. Basic carbohydrates of animals, their content in tissues, biological role. Basic carbohydrates of food. Digestion of carbohydrates.
86. Glucose as the most important metabolic metabolite: general scheme sources and ways of using glucose in the body.
87. Glucose catabolism. Aerobic breakdown is the main pathway for glucose catabolism. Stages, energy. Distribution and physiological significance of the process.
88. Anaerobic breakdown of glucose (anaerobic glycolysis). Glycolytic oxidation, substrate phosphorylation. Biological significance.
89. Biosynthesis of glucose (gluconeogenesis) from lactic acid. The relationship between glycolysis in muscles and gluconeogenesis in the liver (Cori cycle).
90. An idea of the pentose phosphate pathway for the transformation of glucose. Stages, energy. Distribution and physiological significance. Pentose phosphate cycle.
91. Structure, properties and distribution of glycogen as a reserve polysaccharide. Glycogen biosynthesis and its mobilization. The role of insulin, glucagon, adrenaline in glycogen metabolism.
92. Hereditary disorders of the metabolism of monosaccharides and disaccharides. Glycogenoses and aglycogenoses.
93. Lipids: definition, classification, most important functions.
94. The most important lipids of human tissues. Reserve lipids and membrane lipids. Characteristics of fatty acids in human tissues.
95. Dietary fats and their digestion. Lipases and phospholipases and their role. Impaired digestion and absorption of lipids. Resynthesis of triacylglycerols in the enterocyte.
96. Transport forms of blood lipids: chylomicrons and lipoproteins, features of chemical composition, structure. Interconversions of different classes of lipoproteins.
97. Reservation and mobilization of fats in adipose tissue. Regulation of fat synthesis and mobilization. The role of insulin and glucagon. Transport of fatty acids.
98. Metabolism of fatty acids. b-oxidation: localization, energetics, biological significance. Metabolic fate of acetyl-CoA.
99. Biosynthesis of fatty acids, components, biosynthesis scheme. Biosynthesis of unsaturated fatty acids.
100. Biosynthesis and use of acetoacetic acid. The physiological significance of this process. Ketone bodies. Causes of ketonemia and ketonuria.
101. Steroid metabolism. Cholesterol, structure, role. Concept of cholesterol biosynthesis. Regulation of synthesis. Hypercholesterolemia and its causes.
102. Atherosclerosis as a consequence of metabolic disorders of cholesterol and lipoproteins.
103. Basic phospholipids of human tissues, their physiological functions. Biosynthesis and breakdown of phospholipids.
104. Main glycolipids of human tissues, structure, biological role. Understanding the biosynthesis and catabolism of glycolipids. Sphingolipidoses.
105. Metabolism of the nitrogen-free residue of amino acids. Glucogenic and ketogenic amino acids. The role of insulin, glucagon, adrenaline and cortisol in the regulation of the metabolism of carbohydrates, fats and amino acids.
106. Diabetes mellitus, causes. The most important biochemical disorders in the metabolism of proteins, lipids and carbohydrates. Changes in the oral cavity in diabetes mellitus.
107. Chemical structure and the role of the main components (proteins, lipids, carbohydrates) in membrane function. General properties membranes: fluidity, transverse asymmetry, selective permeability.
108. The main functions of biomembranes. Endocytosis and exocytosis, their functional significance.
109. Mechanism of substance transfer through membranes: simple diffusion, primary active transport, secondary active transport (symport, antiport). Regulated transmembrane channels.
110. Biochemistry of blood. Features of the development, structure and chemical composition of erythrocytes. Heme biosynthesis. The structure of the hemoglobin molecule.
111. Respiratory function of blood: transport of oxygen by blood. Carboxyhemoglobin, methemoglobin. Transport of carbon dioxide in the blood. Anemic hypoxia.
112. Hemoglobin breakdown. Bilirubin formation. Neutralization of bilirubin. “Direct” and “indirect” bilirubin.
113. Violation of bilirubin metabolism. Jaundice (hemolytic, obstructive, hepatocellular). Jaundice of newborns.
114. Iron metabolism. Transferrin and ferritin. Iron deficiency anemia. Idiopathic hemochromatosis.
115. Protein spectrum of blood plasma. Albumins and their functions. Globulins, brief characteristics, functions. Acute phase proteins. Blood enzymes. Their origin.
116. Non-protein nitrogen-containing and nitrogen-free substances in blood plasma, origin, diagnostic value of definition.
117. Mineral components of blood. Distribution between plasma and cells, normal ranges of fluctuations of the most important of them.
118. Electrolyte composition of body fluids. The mechanism for maintaining the volume, composition and pH of body fluids.
119. Blood buffer systems. Disorders of the acid-base state of the body. Causes of development and forms of acidosis and alkalosis.
120. The role of the kidneys in the regulation of water and electrolyte metabolism. The structure and mechanism of the regulatory action of vasopressin and aldosterone.
121. Regulation of vascular tone. Brief characteristics of the renin-angiotensin and kallikrein-kinin systems, their relationship.
122. Blood clotting. Internal and external coagulation mechanisms. Cascade mechanism of blood coagulation processes. The role of vitamin K in blood clotting.
123. Anticoagulant system. Natural blood anticoagulants. Hemophilia.
124. Fibrinolytic blood system. Plasminogen, its activation. Disorders of blood clotting processes. DIC syndrome.
125. Connective tissue, types, metabolic and functional features connective tissue cells.
126. Fibrous structures of connective tissue. Collagen: variety of types, features of amino acid composition, primary and spatial structure, biosynthesis.
127. Self-assembly of collagen fibrils. "Aging" of collagen fibers.
128. Connective tissue elastin: features of the amino acid composition and spatial structure of the molecule. Non-collagenous connective tissue proteins.
129. Catabolism of collagen and elastin. Weakness of the antioxidant system in connective tissue.
130. Glycosaminoglycans and proteoglycans of connective tissue: structure and functions.
131. Biosynthesis and postsynthetic modification of glycosaminoglycans and proteoglycans of connective tissue. Degradation of the basic substance of connective tissue.
132. Bone tissue: the ratio of organic and mineral components, features of bone tissue metabolism.
133. The role of vitamins C, D, A and K in the metabolism of bone and dental tissues. Regulation of metabolic processes. Osteoporosis and osteomalacia.
134. Hormonal regulation of osteogenesis, remodeling and mineralization of bone tissue.
135. Composition and metabolic characteristics of a mature tooth.
136. Saliva: mineral and organic components, their biological functions.
137. The main groups of salivary proteins, their role. Salivary enzymes. Diagnostic value of determining the activity of salivary enzymes.
138. Metabolic functions of fluoride. Routes of fluoride entry into the body and their elimination. Distribution of fluoride in the body.
139. The role of fluoride ions in the processes of mineralization of bone and dental tissues. Toxic effects of excess fluoride. Manifestation of fluoride deficiency. The use of fluoride preparations in dentistry.
140. The role of the liver in vital processes. Detoxifying function of the liver. Metabolism of neutralization of foreign substances: reactions of microsomal oxidation and conjugation.
141. Neutralization of toxins, metabolites, biologically active substances, rotting products in the liver (examples).
142. Oxygen toxicity: formation of reactive oxygen species, their effect on lipids. Membrane lipid peroxidation. Antioxidant system.
143. Concept of chemical carcinogenesis.
144. Chemical composition of gray and white matter of the brain. Myelin. Structure, lipid composition.
145. Elementary acts of nervous activity. The role of the transmembrane ion gradient in the transmission of nerve impulses.
146. The most important mediators of nerve impulses and their receptors. Neuropeptides.
147. Features of energy metabolism in nervous tissue.
148. Chemical composition of muscle tissue. The main proteins of myofibrils and sarcoplasm. The role of myoglobin.
149. The mechanism of muscle contraction and relaxation. Features of energy metabolism in muscle tissue.
Biochemical constants and elements
What is biochemistry? Biological or physiological biochemistry is the science of chemical processes that underlie the life of an organism and those that occur inside a cell. The purpose of biochemistry (the term comes from the Greek word “bios” - “life”) as a science is the study chemical substances, structure and metabolism of cells, the nature and methods of its regulation, the mechanism of energy supply for processes within cells.
Medical biochemistry: the essence and goals of science
Medical biochemistry - the section that studies chemical composition cells of the human body, metabolism in it (including in pathological conditions). After all, any disease, even in an asymptomatic period, will inevitably leave its mark on the chemical processes in cells and the properties of molecules, which will be reflected in the results of biochemical analysis. Without knowledge of biochemistry, it is impossible to find the cause of the disease and the way to effectively treat it.
Biochemical blood test
What is a blood chemistry test? Biochemical blood testing is one of the laboratory diagnostic methods in many areas of medicine (for example, endocrinology, therapy, gynecology).
It helps to accurately diagnose the disease and examine a blood sample using the following parameters:
Alanine aminotransferase (ALAT, ALT);
Cholesterol or cholesterol;
Bilirubin;
Urea;
Diastasis;
Glucose, lipase;
Aspartate aminotransferase (AST, AST);
Gamma-glutamyl transpeptidase (GGT), gamma GT (glutamyl transpeptidase);
Creatinine, protein;
Antibodies to Epstein-Barr virus.
For the health of every person, it is important to know what blood biochemistry is and to understand that its indicators will not only provide all the data for an effective treatment regimen, but will also help prevent disease. Deviations from normal indicators- this is the first signal that something is wrong in the body.
blood for liver research: significance and goals
In addition, biochemical diagnostics will allow monitoring the dynamics of the disease and treatment results, creating a complete picture of metabolism, deficiency of microelements in organ function. For example, liver biochemistry will be a mandatory test for people with liver dysfunction. What is this? This is the name of a biochemical blood test to study the quantity and quality of liver enzymes. If their synthesis is impaired, then this condition threatens the development of diseases and inflammatory processes.
Specifics of liver biochemistry
Biochemistry of the liver - what is it? The human liver consists of water, lipids, and glycogen. Its tissues contain minerals: copper, iron, nickel, manganese, so the biochemical study of liver tissue is a very informative and quite effective analysis. The most important enzymes in the liver are glucokinase and hexokinase. The following liver enzymes are most sensitive to biochemical tests: alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST). As a rule, the study is guided by the indicators of these substances.
For complete and successful monitoring of their health, everyone should know what “biochemistry analysis” is.
Areas of biochemistry research and the importance of correct interpretation of analysis results
What does biochemistry study? First of all, metabolic processes, the chemical composition of the cell, the chemical nature and function of enzymes, vitamins, acids. It is possible to evaluate blood parameters using these parameters only if correct decoding analysis. If everything is fine, then blood parameters for various parameters (glucose level, protein, blood enzymes) should not deviate from the norm. Otherwise, this should be regarded as a signal of a malfunction of the body.
Decoding biochemistry
How to decipher the numbers in the analysis results? Below are the main indicators.
Glucose
The glucose level shows the quality of the carbohydrate metabolism process. The limiting norm of content should not exceed 5.5 mmol/l. If the level is lower, this may indicate diabetes mellitus, endocrine diseases, and liver problems. Elevated glucose levels may be due to diabetes, physical activity, hormonal medications.
Protein
Cholesterol
Urea
This is the name given to the end product of protein breakdown. In a healthy person, it should be completely eliminated from the body in the urine. If this does not happen, and it gets into the blood, then you should definitely check your kidney function.
Hemoglobin
This is a red blood cell protein that saturates the body's cells with oxygen. Norm: for men - 130-160 g/l, for girls - 120-150 g/l. Low level hemoglobin in the blood is considered one of the indicators of developing anemia.
Biochemical blood test for blood enzymes (ALAT, AST, CPK, amylase)
Enzymes are responsible for the proper functioning of the liver, heart, kidneys, and pancreas. Without the required amount, a complete exchange of amino acids is simply impossible.
The level of aspartate aminotransferase (AST, AST - a cellular enzyme of the heart, kidneys, liver) should not be higher than 41 and 31 units/l for men and women, respectively. Otherwise, this may indicate the development of hepatitis and heart disease.
Lipase (an enzyme that breaks down fats) plays an important role in metabolism and should not exceed 190 units/l. An elevated level indicates a malfunction of the pancreas.
It is difficult to overestimate the importance of biochemical analysis for blood enzymes. Every person who cares about their health must know what biochemistry is and what it studies.
Amylase
This enzyme is found in the pancreas and saliva. It is responsible for the breakdown of carbohydrates and their absorption. Norm - 28-100 units/l. Its high level in the blood may indicate renal failure, cholecystitis, diabetes, peritonitis.
The results of a biochemical blood test are recorded on a special form, which indicates the levels of substances. Often this analysis is prescribed as an additional one to clarify the intended diagnosis. When deciphering the results of blood biochemistry, keep in mind that they are also influenced by the patient’s gender, age and lifestyle. Now you know what biochemistry studies and how to correctly interpret its results.
How to properly prepare for donating blood for biochemistry?
Acute diseases of internal organs;
Intoxication;
Vitamin deficiency;
Inflammatory processes;
For the prevention of diseases during pregnancy;
To clarify the diagnosis.
Blood for analysis is taken early in the morning, and you cannot eat before coming to the doctor. Otherwise, the analysis results will be distorted. A biochemical study will show how correct your metabolism and salts in the body are. In addition, refrain from drinking sweet tea, coffee, or milk at least an hour or two before blood sampling.
Be sure to answer the question of what biochemistry is before taking the test. Knowing the process and its significance will help you correctly assess your health status and be competent in medical matters.
How is blood taken for biochemistry?
The procedure does not last long and is practically painless. From a person in a sitting position (sometimes they offer to lie down on the couch), the doctor takes it after applying a tourniquet. The injection site must be treated with an antiseptic. The collected sample is placed in a sterile tube and sent for analysis to the laboratory.
Quality control of biochemical research is carried out in several stages:
Preanalytical (patient preparation, analysis, transportation to the laboratory);
Analytical (processing and storage of biomaterial, dosing, reaction, result analysis);
Post-analytical (filling out a form with the result, laboratory and clinical analysis, sending to the doctor).
The quality of the biochemistry result depends on the appropriateness of the chosen research method, the competence of laboratory technicians, the accuracy of measurements, technical equipment, the purity of reagents, and adherence to diet.
Biochemistry for hair
What is biochemistry for hair? Biocurling is a method of long-term curling of curls. The difference between a regular perm and a bioperm is fundamental. In the latter case, hydrogen peroxide, ammonia, and thioglycolic acid are not used. The role of the active substance is played by a cystine analogue (biological protein). This is where the name of the hair styling method comes from.
The undoubted advantages are:
Gentle effect on the hair structure;
Blurred line between regrown and bio-permed hair;
The procedure can be repeated without waiting for its effect to completely disappear.
But before going to the master, you should consider the following nuances:
The biowave technology is relatively complex, and you need to be meticulous in choosing a specialist;
The effect is short-lived, about 1-4 months (especially on hair that has not been permed, dyed, or has a dense structure);
Bioperm is not cheap (on average 1500-3500 rubles).
Biochemistry methods
What is biochemistry and what methods are used for research? Their choice depends on its purpose and the tasks set by the doctor. They are designed to study the biochemical structure of the cell, examine the sample for possible deviations from the norm and thus help diagnose the disease, find out the dynamics of recovery, etc.
Biochemistry is one of the most effective tests for clarifying, making a diagnosis, monitoring treatment, and determining a successful treatment regimen.
Structure, properties and functions of proteins.
Elucidation of the structure of proteins is one of the main problems of modern biochemistry.
Protein molecules are high molecular weight compounds formed by amino acids.
Most proteins have 4 levels of organization (4 structures of the protein molecule).
Primary structure of a protein.
Currently, the primary structure of about 2500 proteins has been deciphered, and in nature there are 10 12 different proteins.
The primary structure is the sequence (order) of connecting amino acid residues using a peptide bond.
A peptide bond is formed by the carboxyl group of one amino acid and the amino group of another amino acid.
-Amino acids participate in the formation of the primary structure.
The peptide bond forms the backbone of the polypeptide chain; it is a repeating fragment.
Features of peptide bond:
Coplanarity - all atoms included in the peptide bond are in the same plane.
Substituents on the C-N bond are in trans position.
A peptide bond is capable of forming two hydrogen bonds with other groups, including peptide groups.
The peptide bond is a strong covalent bond, the bond energy is 110 kcal/mol.
Properties of protein primary structure
Determination - the sequence of amino acids in a protein is genetically encoded.
Amino acid sequence information is contained in DNA.
Uniqueness – each protein in the body is characterized by a specific sequence of amino acids.
Amino acids that make up proteins are divided into 2 groups:
Interchangeable amino acids are amino acids that are similar in structure and properties.
Non-interchangeable amino acids that differ in structure and properties.
There are 2 types of amino acid substitutions in a protein molecule:
Conservative - replacement of one amino acid with another similar in structure. Such a replacement does not change the properties of the protein.
Examples: gli-ala, asp-glu, tir-fen, val-ley.
Radical substitution is the replacement of one amino acid with another that differs in structure. This replacement leads to changes in the properties of the protein.
Examples: glu-val, ser-cis, pro-tri, fen-asp, ile-met.
Radical replacement of Glu with Val in the sixth position in the hemoglobin molecule leads to the development of sickle cell anemia. With this pathology, red blood cells under conditions of low partial pressure take on a sickle shape. After the release of oxygen, such hemoglobin is converted into a poorly soluble form and begins to precipitate in the form of spindle-shaped crystalloids called tactoids. Tactoids deform the cell and red blood cells take on a sickle shape. In this case, hemolysis of red blood cells occurs. The disease is acute and children die. This pathology is called sickle cell anemia.
Universality of the primary structure. Proteins that perform the same functions in different organisms have the same or similar primary structure.
In natural proteins, the same amino acid does not occur more than 3 times in a row.
Secondary structure of protein.
Secondary structure is the way a polypeptide chain is folded into a helical or folded conformation.
Conformation is the spatial arrangement in an organic molecule of substituent groups that can freely change their position in space without breaking bonds, due to free rotation around single carbon bonds.
There are 2 types of protein secondary structure:
1. -spiral
2. - folding.
The secondary structure is stabilized by hydrogen bonds. Hydrogen bonds occur between the hydrogen atom in the NH group and the carboxyl oxygen.
Characteristics - spirals.
Each protein is characterized by its own degree of helicity of the polypeptide chain. Spiral sections alternate with linear ones. In the hemoglobin molecule, the β-chains are helical by 75%, in lysozyme - 42%, in pepsin - 30%.
The degree of helicalization depends on the primary structure of the protein.
The amino acid proline prevents the spiralization of the protein molecule.
Folding has a slightly curved configuration of the polypeptide chain.
Folding is characterized by hydrogen bonds within one polypeptide chain or complex polypeptide chains.
In proteins, transitions from -helix to -folding and back are possible due to rearrangement of hydrogen bonds.
The folding has a flat shape.
The spiral has a rod shape.
Hydrogen bonds are weak bonds, the bond energy is 10–20 kcal/mol, but a large number of bonds ensures the stability of the protein molecule.
In a protein molecule there are strong (covalent) bonds, as well as weak ones, which ensures the stability of the molecule on the one hand, and lability on the other.
Tertiary structure of a protein.
The tertiary structure of a protein is the way the polypeptide chain is arranged in space.
Based on the shape of the tertiary structure of the protein, they are divided into globular and fibrillar.
Covalent bonds (peptide and disulfide) are involved in stabilizing the tertiary structure of a protein molecule. The main role in stabilization is played by non-covalent bonds: hydrogen, electrostatic interactions of charged groups, intermolecular van der Waals forces, interactions of non-polar side radicals of amino acids, so-called hydrophobic interactions.
Hydrophobic amino acid radicals ala, val, isol, met, phen interact with each other in an aqueous environment. In this case, non-polar hydrophobic amino acid radicals seem to be immersed inside the protein molecule, forming dry zones there, and polar radicals are oriented towards water.
When folded, the polypeptide chain of a protein tends to take on an energetically favorable form with less energy odor.
When the tertiary structure is formed, the polypeptide chain bends at the locations of proline and glycine.
Globular proteins are soluble in water, but fibrillar proteins are not.
Quaternary structure of protein.
Proteins consisting of one polypeptide chain have only a tertiary structure (lysozyme, pepsin, myoglobin, trypsin).
Proteins consisting of several polypeptide chains are characterized by a quaternary structure.
Quaternary structure is understood as the combination of individual polypeptide chains with a tertiary structure into a functionally active protein molecule. Each individual polypeptide chain is called a protomer and often has no biological activity.
A protein molecule can have several protomers, which when combined form an oligomer or multimer.
Proteins with a quaternary structure are characterized by the concept of a subunit.
A subunit is the functionally active part of a protein molecule.
An example of a protein with a quaternary structure is hemoglobin, consisting of 4 protomers: 2 and 2 chains.
The interaction of polypeptide chains during the formation of an oligomer occurs due to polar groups of amino acid residues. Ionic, hydrogen bonds, and hydrophobic interactions are formed between polar groups.
Denaturation.
Denaturation is the process of disruption of the highest levels of organization of a protein molecule (secondary, tertiary, quaternary) under the influence of various factors.
In this case, the polypeptide chain unfolds and is in solution in an unfolded form or in the form of a random coil.
During denaturation, the hydration shell is lost and the protein precipitates and at the same time loses its native properties.
Denaturation is caused physical factors: temperature, pressure, mechanical influences, ultrasonic and ionizing radiation; chemical factors: acids, alkalis, organic solvents, alkaloids, salts of heavy metals.
There are 2 types of denaturation:
Reversible denaturation - renaturation or reactivation - is a process in which a denatured protein, after removal of denaturing substances, self-organizes again into its original structure with restoration of biological activity.
Irreversible denaturation is a process in which biological activity is not restored after the denaturing agents are removed.
Properties of denatured proteins.
An increase in the number of reactive or functional groups compared to the native protein molecule (these are groups COOH, NH 2, SH, OH, groups of side radicals of amino acids).
Reduced solubility and precipitation of the protein (associated with the loss of the hydration shell), unfolding of the protein molecule, with the “detection” of hydrophobic radicals and neutralization of the charges of polar groups.
Changing the configuration of a protein molecule.
Loss of biological activity caused by disruption of the native structure.
Easier cleavage by proteolytic enzymes compared to the native protein - the transition of the compact native structure into an expanded loose form makes it easier for enzymes to access the peptide bonds of the protein, which they destroy.
Enzymatic methods of hydrolysis are based on the selectivity of the action of proteolytic enzymes that cleave peptide bonds between certain amino acids.
Pepsin cleaves bonds formed by phenylalanine, tyrosine and glutamic acid residues.
Trypsin breaks down the bonds between arginine and lysine.
Chymotrypsin hydrolyzes the bonds of tryptophan, tyrosine and phenylalanine.
LESSON 3
Structure and properties of enzymes.
Enzymes (enzymes) are specific proteins that are part of all cells and tissues of living organisms, playing the role of biological catalysts.
Evidence of the protein nature of enzymes.
Isoelectric point of enzymes.
Behavior of enzymes when the concentration of hydrogen genes changes.
High enzyme specificity.
Enzymes are unable to penetrate semipermeable membranes.
Preservation of enzyme activity after exposure to water-removing agents (acetone, alcohol, neutral salts of alkali metals).
Initiation of enzymes by heating. Enzyme inactivation coincides with protein denaturation. Enzymes are also destroyed by the action of mineral acids, alkalis, salts, alkaloids, and irradiation with X-rays and ultraviolet rays.
Electrochemical properties of enzymes.
Enzymes and inorganic catalysts share common properties:
Inorganic catalysts and biological catalysts - enzymes are required in small quantities to carry out a reaction.