Question

What is denaturation of proteins?

Hint:

Denaturation ≠ hydrolysis: shape changes and activity is lost, but peptide backbone (primary structure) remains intact.

Answer 1

Step 1: Definition.
Denaturation is the process in which a protein loses its native three-dimensional structure (secondary/tertiary/quaternary levels) due to disruption of non-covalent interactions (H-bonds, hydrophobic interactions, ionic bonds) and some S–S bridges, \emph{without breaking the peptide bonds} of the primary structure.
Step 2: Causes.
Heat, extreme pH, heavy metal salts (Hg$^{2+}$, Pb$^{2+}$), organic solvents (alcohols), urea/guanidinium salts, radiation, etc.
Step 3: Consequences.
Loss of biological activity (e.g., loss of enzyme function), loss of solubility, coagulation/precipitation.
Step 4: Examples.
- Coagulation of egg white on boiling.
- Curdling of milk with acid.
- High fever affecting enzyme activity.
Step 5: Note.
Renaturation is sometimes possible if the denaturing agent is removed gently and the primary structure remains intact.