JEE Main 2023 · 10 April · morning · Single correct · +4 / −1
The one that does not stabilize 2° and 3° structures of proteins is
- (a) -O -O -linkage
- (b) -S -S -linkage
- (c) van der Waals forces
- (d) H-bonding
Answer and solution
Answer (a) -O -O -linkage
Solution
Chemistry ma’am · 3 steps
Ask which link a protein can actually form between its side chains. Proteins have no peroxide links.
- Secondary structure. The α-helix and β-pleated sheet are held by hydrogen bonds. They form between the C=O of one peptide bond and the N-H of another.
- Tertiary structure. The folded 3D shape is held by interactions between side chains. These include hydrogen bonds, disulfide bridges between two cysteine residues, van der Waals forces, ionic attractions and hydrophobic interactions.
Linkage or force Found in proteins? Where it acts -O-O⁻ (peroxide) No no amino acid side chain forms it -S-S⁻ (disulfide) Yes between two cysteine -SH groups, in tertiary structure van der Waals forces Yes between non-polar side chains, in tertiary structure H-bonding Yes main force in secondary structure, also helps tertiary - So. The -O-O⁻ linkage plays no part in protein structure, so the answer is (a).
The idea to keep. Secondary structure is held by H-bonds. Tertiary structure is held by H-bonds, -S-S⁻ bridges, van der Waals forces, ionic and hydrophobic interactions. Peroxide links never appear.
Answer from the NTA final answer key. Solution by PrepWiser.