Questions to study.
1. Proteins, their definition, biological role and classification.
2. Amino acids as monomers of proteins, their classifications and chemical properties. Structure of standard amino acids.
3. Primary structure of protein. Structure of peptide bond. Hereditary defects of primary protein structure. Relationship between structure and function of protein.
Secondary, tertiary and quaternary structures of protein: definition, types of bonds stabilizing these structures. Their specific properties and significance.
4. Simple proteins (albumins, globulins, histones): structure, classification, representatives, biological role.
5. Physical and chemical protein properties: acidic and basic properties, denaturation, solubility, salting, osmotic pressure, dialysis.
Assignment for self-instruction
| | Guidelines for performing the task |
| | |
| What is medical significance of the structure, functions and biological role of proteins? | 1. Describe the chemical composition of living systems. 2. Describe functional diversity of proteins - enzymes, receptors, transporting proteins, antibodies. Give examples of protein hormones, structural and contractile proteins |
Continued of the table
| | |
| Study the levels of protein folding | 1. Give definition of the term primary structure of protein. 2. Write the structural formula of Met-Pro-Ileu tripeptide. 3. What does secondary structure of protein mean and what types of secondary structure do you know? Characterize the bond stabilizing the secondary structure. 4. Draw the schemes of α-helix и ß-pleated sheet. 5. What does tertiary structure of protein mean? Characterize the bonds stabilizing the tertiary structure. 6. What does quaternary structure of protein mean? Oligomeric proteins. Give examples of oligomeric proteins |
| Study the methods used for researching the protein primary structure | 1. What types of protein hydrolysis do you know? 2. What is the principle of chromatography? Describe the classification of chromatographic methods. 3. Describe the sequence of determining protein primary structure. 4. What is the practical significance of knowing amino acid composition of protein and its primary structure? |
| Study modern views on protein structure | 1. What does folding of protein mean? The role of chaperones and heat shock proteins in supporting protein native structure. 2. What does prion diseases mean? |
| Study the methods of researching protein secondary, tertiary and quaternary structure | 1. List and characterize the methods of researching protein secondary, tertiary and quaternary structure |
| Study biological significance of proteins | 1. Name biological functions of proteins in human body |
| Study the process of protein solubilisa-tion | 1. Describe the features of protein solutions. 2. What are two main factors that stabilize proteins in solutions? 3. Give the definition of the term salting-out. Describe the mechanism of salting-out. 4. Give examples of practical uses for salting-out. 5. Give the definition of denaturation of proteins. List the types of de-naturation. 6. Explain the mechanism of denaturing effect of the temperature, heavy metal salts, alcohols, and phenols. 7. Give examples of practical use of protein denaturation in medicine |
Ending of the table
| | |
| Study electrical properties of proteins | 1. Explain amphoteric properties of proteins. 2. Write down the reaction of dissociation of carboxyl groups and amino groups in the protein molecule. 3. Describe two main factors which predetermine the electrical charge of the protein molecule. 4. What does isoelectric point of the proteins mean? What do you know about protein properties at the isoelectric point? |
Library-research paper
1. Prions and prion diseases.
LABORATORY WORK 1. Dialysis of proteins
Dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane like cellophane. Dialysis allows removal of small molecules (salts, reducing agents, dyes, etc) from high molecular weight substances such as proteins.
Procedure
► Take a tube. Pour 1 drop of saturated ammonium sulfate solution and 5 ml of 3% egg protein solution. Stir well.
► Pour 10 drops of this solution into two clean tubes.
► Make biuret test with continuation of the first tube.
► For this purpose add 10 drops of 10% NaOH solution and 1 drop of 1% copper sulfate solution. Mix well. Characteristic violet-blue coloration appears.
► Make a sulfate-ion analysis in the second one. For this purpose add 2-3 drops of 5% barium chloride solution to the second tube.