Question

Why does the presence of proline destabilize α-helix?
(A) Proline residue introduces a destabilizing kink in the α-helix
(B) In proline, the nitrogen atom is a part of a rigid ring, and rotation about N-C bond is not possible
(C) The nitrogen atom of a proline residue in a peptide linkage has no substituent hydrogen to participate in hydrogen bonds with other residues
(D) Proline residue works as a helix linker
Choose the correct answer from the options given below:

• A. (A), (B), and (D) only
• B. (A), (B), and (C) only
• C. (A), (B), (C), and (D)
• D. (B), (C) and (D) only

Hint:

Focus on the structural characteristics of proline and how they affect the α-helix stability.

Answer 1

The Correct Option is B

Proline is unique due to its cyclic structure, which introduces a sharp kink in the α-helix, disrupting its regular helical conformation. The nitrogen atom in proline is part of a rigid ring, making rotation around the N-C bond impossible. Additionally, proline lacks a hydrogen atom on its nitrogen to participate in backbone hydrogen bonding, which is essential for α-helix stability.