During denaturation of proteins, which of the following bond/ interaction is not broken?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Peptide bonds
Denaturation unfolds a protein but leaves its primary structure, the chain of amino acids joined by peptide bonds, intact; breaking peptide bonds is hydrolysis, not denaturation.
Option (1) Electrostatic attraction — Broken during denaturation. Salt bridges between charged side chains are broken, especially when the pH changes.
Option (2) Hydrogen bonds — Broken during denaturation. These hold the α-helix and β-pleated sheet and are the first to be disturbed.
Option (3) Disulphide bonds — Broken during denaturation. These help hold the tertiary structure and are broken when the protein unfolds.
Option (4) Peptide bonds — Not broken during denaturation. They make up the primary structure, which stays intact.
NCERT (2026-27 edition):
Denaturation of Proteins
