- •Federal Agency of Education tambov state university named after g.R. Derzhavin
- •Biochemistry (part I)
- •Tambov 2012
- •I. Theoretical part The subject Of biological chemistry
- •1. Chemistry of proteins
- •1.1. Methods of exctraction and purification of proteins
- •1.2. Functions of proteins
- •1.3. Amino-acid composition of proteins
- •1.4. The structural organization of proteins
- •1.5. Physical and chemical properties of proteins
- •1.6. Classification of proteins
- •1.6.1. Simple proteins
- •1. Albumins and globulins.
- •2. Protamines and histones.
- •3. Prolamins and glutelins.
- •1.6.2. Conjugative proteins
- •1. Proteins containing non-heme iron.
- •Nucleic acids
- •The structure of nucleic acids
- •Test Questions
- •2. Enzymes
- •2.1. The chemical nature of enzymes
- •2.2. The mechanism of enzymes action
- •2.3. Kinetics of enzymatic reactions
- •2.4. Enzyme properties
- •2.5. Regulation of enzyme activity
- •1. Control of the enzyme amount.
- •2. Control of enzyme activity.
- •2.1. The influence of activators and inhibitors on the enzymes.
- •2.3. Chemical modification of the enzyme.
- •2.4. Allosteric regulation.
- •2.6. Classification and nomenclature of enzymes
- •2.7. Enzymes in medicine
- •Test Questions
- •3. Vitamins
- •3.1. Fat soluble vitamins
- •3.2. Water soluble vitamins
- •Vitamin-like substances
- •Test Questions
- •4. Basic principles of biomembranes’ organisation
- •4.1. Structure and functions of membranes
- •1. Phospholipids (90%) - glycerophospholipids and sphingophospholipids:
- •4.2. Transport of substances across membranes
- •2. Facilitated diffusion
- •Test Questions
- •5. Transmembrane transduction of the hormonal signal
- •Test Questions
- •6. Introduction to metabolism
- •6.1. Stages of catabolism
- •III. A common catabolic pathway.
- •6.2. Bioenergetics
- •6.3. Organization and operation of the respiratory chain
- •6.4. Uncoupling of oxidation from phosphorylation
- •6.5. Generation of free radicals in cells
- •6.6. Reactions of the common catabolic pathway
- •6.6.1. Oxidative decarboxylation of pyruvate
- •6.6.2. Citric acid cycle
- •7. Carbohydrate metabolism
- •7.1. Digestion of carbohydrates
- •7.2. Glycogen metabolism
- •7.3. Glycolysis
- •7.4. The inclusion of fructose and galactose
- •In glycolysis
- •7.5. The shuttle mechanisms
- •7.6. Cori cycle
- •7.7. Alcoholic fermentation
- •C6h12o6 → 2 ch3chohcooh
- •7.8. Pentose phosphate pathway (hexose monophosphate shunt)
- •7.9. Gluconeogenesis
- •Synthesis of glucose from the pyruvic acid.
- •Fructose bisphosphatase
- •Glucose-6-phosphatase
- •7.10. Regulation of carbohydrate metabolism
- •Glucose → glucose-6-phosphate.
- •Pyruvate → oxaloacetate → phosphoenolpyruvate
- •7.11. Violations of carbohydrate metabolism
- •Violation of hydrolysis and absorption of carbohydrates
- •Violations of the intermediate metabolism of carbohydrates
- •Quiz Questions
- •II. Laboratory practice Laboratory work 1. The analysis of amino acids and proteins
- •1. Qualitative analysis of amino acid mixtures by thing layer chromatography method.
- •2. Colour reaction of proteins.
- •2.1. Millon’s reaction.
- •2.2. Ninhydrin’s reaction.
- •3. Reactions of precipitation of proteins.
- •3.1. Precipitation of proteins with salts of heavy metals.
- •3.3. Precipitation of proteins with the help of concentrated mineral acids.
- •3.4. Precipitation of proteins by organic acids.
- •Test questions
- •Laboratory work 2. Conjugated proteins: glycoproteins and phosphoproteins
- •1. Phosphoproteins.
- •1.1. Proof of protein component’s present in the casein hydrolyzate.
- •1.2. Proof of phosphoric acid’s presence in the casein hydrolyzate.
- •1.3. Determination of the isoelectric point of casein.
- •2.4. Proof of carbohydrate’s presence in the egg albumin.
- •Test questions
- •Laboratory work 3. Conjugated proteins: nucleoproteins and chromoproteins
- •1. Nucleoproteins
- •1.1. Isolation of deoxyribonucleoproteins from the spleen.
- •1.2. Reaction with diphenylamine.
- •2. Chromoproteins.
- •2.1. Benzidine test for hemin group of hemoglobin.
- •Test questions
- •Laboratory work 4. Enzymes
- •1. Detection of peroxidase in potatoes.
- •2. Detection of pepsin in the gastric juice.
- •3. Hydrolysis of starch by α-amylase.
- •4. Specificity of amylase and sucrase enzymes action.
- •Test questions
- •Laboratory work 5. Identifying the activity of enzymes
- •1. The influence of activators and inhibitors upon activity of enzymes.
- •1. The influence of activators and inhibitors upon α-amylase.
- •1.2. Inhibitory effect of chloride ions on dehydrogenase complex of potatoes.
- •2. Identifying the activity of α-amylase according to Wolgemut.
- •Test questions
- •Inhibitor calimine
- •Laboratory work 6. Vitamins
- •Vitamin a (vitamin a, retinol)
- •Vitamin d (calciferol)
- •3.1. Reaction with concentrated nitric acid.
- •3.2. Reaction with ferric chloride (III).
- •9.2. Reaction with methylene-blue.
- •Test questions
- •Laboratory work 7. Oxidoreductases. Common catabolic pathway
- •1. Comparison of redox-potentials of riboflavin and methylene blue.
- •2. Identifying of catalase activity according to a.N. Bach and а.I. Oparin.
- •Test questions
- •Laboratory work 8. Carbohydrate metabolism
- •2.1. Trommer’s test with copper hydroxide.
- •2.2. Discovery of fructosuria by Selivanov’s test.
- •2.3. Enzymatic method of semi-quantitative identification of glucose in urine with the help of "GlucoPhan" test strip.
- •Test questions
- •References
Test Questions
1. Describe the chemical nature and structure of enzymes.
2. What is the structure of the active center of enzyme? What is the allosteric center?
3. Give examples of isozymes; multimolecular enzyme systems.
4. On what basis enzymes are classified?
5. Describe the mechanism of enzyme action.
6. What is the difference between the theories of Fisher and Koshland?
7. How do changes in pH and temperature influence on the rate of enzymatic reactions?
8. What is meant by the specificity of enzyme action?
9. How is the regulation of enzyme activity done?
10. What types of enzymes inhibition do you know?
11. How can be carried out in practice the determination of the enzymes activity?
12. Give examples of the enzymes usage in medicine.
3. Vitamins
Vitamins (from Lat. vita - life) are organic compounds required in the diet in small amounts. They ensure the normal development of human and animal, and an adequate rate of occurrence of biochemical and physiological processes.
Vitamins are the assembly group of organic compounds in the chemical and physical point of view. The physiological effects of vitamins are also very different.
100 years ago it was believed that for the normal life of the human organism flux of proteins, fats, carbohydrates, minerals and water is enough. Practice and experience have shown that there are specific diseases which development is directly related to malnutrition (scurvy, beriberi).
The need for vitamins is negligible: approximately a person should consume daily 0.1 - 0.2 g. of vitamins. In many cases, vitamins are components of enzymes.
Avitaminosis (vitamin deficiency) is a disease that occurs in the absence of food vitamins or in total violation of assimilation of any vitamin.
Hypovitaminosis is insufficient intake of vitamins with food or their incomplete assimilation.
Hypervitaminosis is pathological state associated with large quantities of vitamins in the organism.
The causes of hypo- and avitaminosis in humans and animals are usually divided into exogenous and endogenous. An exogenous factor is insufficient intake of vitamins or their complete absence in the diet. Endogenous factors are: a) increased requirement for vitamins in certain physiological and pathological conditions (pregnancy, hyperthyroidism); b) violation of the process of absorption of vitamins in the digestive tract diseases; c) enhanced disruption of vitamins in the intestine due to the development of its flora; d) liver, pancreas diseases, accompanied by malabsorption of fat and therefore fat-soluble vitamins.
The classification is currently used based on the solubility of the vitamins.
3.1. Fat soluble vitamins
Vitamin A (retinol). Vitamin A has several vitamers.
Vitamer is a substance similar in chemical structure and having physiological effects characteristic of a particular vitamin.
Retinol is oxidized in the organism with the participation of the biocatalyst. It is converted to retinal, also having the activity of vitamin A.
Vitamin A affects the barrier function of skin, mucous membranes, the permeability of cell membranes and biosynthesis of glycoproteins, it is involved in light perception, being a part of the photosensitive pigment rhodopsin.
Vitamin A deficiency leads to inhibition of growth, weight loss, lesions of skin, mucous membranes and eyes (night blindness).
Vitamin A is found in liver, egg yolk, milk, oil; provitamin A (carotene) - in red pulp vegetables. Daily requirement is 2.7 mg. In humans body vitamin A is stored mostly in liver.
There are cases of A hypervitaminosis at eating polar bear, seal, walrus liver, which contains plenty of vitamin A. Hypervitaminosis may develop as a result of receiving large amounts of fish oil and preparations with vitamin A. The characteristics of hypervitaminosis are eye inflammation, hair loss, headaches, dyspepsia (nausea, vomiting) dermatitis.
Vitamin D (calciferol) in the human organism exists as a form of D2 and D3. Precursor of vitamin D2 (ergocalciferol) is ergosterol, which is present in plants. Precursor of vitamin D3 (cholecalciferol) is cholesterol, which is present in animals. Ergosterol and cholesterol are transformed into D2 and D3 under the influence of solar radiation.
Calciferols are involved in the regulation of calcium and phosphorus digestion in the intestine, in osteogenesis, in the synthesis of mRNA and Ca-binding proteins and hormones.
Vitamin D deficiency in children leads to rickets. The result is bone softening and deformation, thickening at the bone-cartilage boundary ribs, large head, enlarged abdomen due to the muscle hypotonia). D avitaminosis in adults leads to osteomalacia and osteoporosis. It is bone demineralisation, causing the bones become fragile.
D hypervitaminosis is observed at very high dosages of vitamin and can be fatal. Toxic effect includes resorption of bones and deposition of phosphates in soft tissues (kidney and arteries).
Vitamin D is found in animal products - butter, liver, egg yolk and oil. Daily requirement is 10 micrograms, for children - 20-25 microgramms. To prevent rickets in children UV irradiation is recommended.
Vitamin E (tocopherol) (from the Greek Tokos - descendants, Fero - bring) got its name because it was established that it regulates the process of reproduction in rats.
Vitamin E is one of the strongest natural antioxidants. It protects polyunsaturated fatty acids and lipids of cell membranes from oxidation, especially from peroxidation reactions.
In the absence or deficiency of vitamin E in humans and animals embryogenesis is disturbed and degenerative changes in the reproductive organs are observed. Degeneration of the spinal cord develops and there is paralysis of limbs, fatty liver, muscular dystrophy, biochemical changes in muscles.
Sources of Vitamin E are mainly vegetable oils, cabbage and grain products. It also contained in meat, milk, butter, eggs. Vitamin E is deposited in muscle, pancreas, so the development of avitaminosis is almost not observed. Daily requirement is 5 milligrams.
Vitamin K (phyllochinone). It regulates the process of blood clotting. Vitamin K deficiency can lead to spontaneous nosebleeds, bloody vomiting and internal bleeding. K avitaminosis is rare. A mixed diet is rich enough with it; the intestinal micro flora is capable of synthesizing vitamin K.
The drug "vikasol" is derived from vitamin К3.