Practical lesson 2

PHYSICAL AND CHEMICAL PROPETIES OF PROTEINS

1.E

2.C

3.D

4.E. The correct folding of a protein is guided by specific interactions among the side chain of the amino acid residues of a polypeptide chain. The two cysteine residues that react to form the disulfide bond may be a great distance apart in the primary structure (or an separate polypeptides), but are brought into close proximity by the three-dimensional folding of the polypeptide chain. Denaturation may either be reversible or irreversible. Quaternary structure requires more than one polypeptide chain. These chains associate through noncovalent interactions.

5.D

6.B

7.E

8.A

9.A

10.B

PRACTICAL LESSON 3

ENZYMES. STRUCTURE AND GENERAL PROPERTIES OF ENZYMES

1. E.

2. E

3. B

4. D

5. C

6. B

7. C

8. B

9. A

10. E

PRACTICAL LESSON 4

MECHANISM OF ENZYME ACTION. REGULATION OF ENZYME ACTIVITY

1.A

2. C

3. D

4.E

5.E

6.A. In the presence of a competitive inhibitor, an enzyme appears to have a lower affinity for substrate, but as the substrate level is increased, the observed velocity approaches V max.

7.D. Km has the dimensions of concentration and is a characteristic of an enzyme under a given set of reaction conditions. Km does not depend on the concentration of enzyme, but can vary with pH. A noncompetitive inhibitor decreases V max but does not alter Km.

8.E

9.E

10.A

PRACTICAL LESSON 5

WATER-SOLUBLE AND FAT- SOLUBLE VITAMINS. VITAMINS AS COFACTORS

1.E

2.E

3.C

4.A

5.B

6.E

7.E