protein classification and denaturation

Question 1

How are proteins classified ?

Answer 1

They are classified according to their :

1. Solubility : Structural and dynamic
2. Shape : Fibrous and Globular
3. Biological value : High biological value and Low biological value

Question 2

How are proteins classified according to their solubility ?

Answer 2

1. Structural : They are insoluble in water , enter in tissue structure ( tough and strong ) like collagen and elastin.
2. Dynamic : They are soluble in water , they have different functions :
   transport function : hemoglobin , transferrin
   regulatory function : hormones
   catalytic function : enzymes
   defense function : immunoglobulins

Question 3

How are proteins classified according to the shape ( axial ratio )

Answer 3

1. Fibrous ( more than 10 )

2. Globular ( less than 4 )

Question 4

What is meant by denaturation of protein ?

Answer 4

1. The loss of the biological relevant conformation of protein.
2. The unfolding and loss of the secondary and tertiary structure of protein.
3. The protein becomes formed of random coils.
4. It is not accompanied by the hydrolysis of the peptide bond.

Question 5

What are the physical denaturing agents of proteins ?

Answer 5

Physical agents :

1. High temperature >60°C
2. High pressure
3. Ultra-Violet rays (UV) and X rays
4. Mechanical agitation
5. Repeated freezing & thawing

Question 6

What are the chemical denaturing agents ?

Answer 6

Chemical agents :

1. Strong acids or alkalis
2. Organic solvents
3. Salts of heavy metals (silver nitrate, mercuric chloride)
4. Urea, detergents

Question 6

What are the chemical denaturing agents ?

Answer 6

Chemical agents :

1. Strong acids or alkalis
2. Organic solvents
3. Salts of heavy metals (silver nitrate, mercuric chloride)
4. Urea, detergents