The Different Uses of Proteins

Distinguish between protein used for structural purposes and the uses of proteins as enzymes


  • is known as the most abundant biomolecule having its building blocks called amino acids
  • can be classified in terms of its shape, function and composition.

Based on Shape:

    • Globular (spherical) – Generally soluble in water
      Example: Hemoglobin
    • Fibrous (thread-like) – Stretched, twisted and generally insoluble in water

Example: Collagen

Based on Composition:

  • Simple – pure protein
    Example: Globulin, Albumin
  • Conjugated – protein with non-protein substances
    Example: Glycoproteins, Lipoproteins

Based on Biological Function:

a. Transport Proteins

b. Nutrient and Storage Proteins

c. Contractile Proteins

d. Defense Proteins

e. Regulatory Proteins

f. Enzymes

– serve as catalyst of biological reactions

– generally globular and water soluble

-contain active site where catalysis occurs

– all enzymes are proteins except for ribozymes

– can be classified as oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases

Examples: Insulin , Hemoglobin, Lipase, Pepsin, Hexokinase, Pyruvate decarboxylase

g. Structural Proteins

– stingy, physically tough and insoluble in water which work for structural support

Example: Keratin in skin, fingernails and hair