Proline as an α-helix breaker
Which amino acid is most likely to disrupt an α-helix?
Answer D: explanation for every choice
A
Alanine is one of the strongest helix formers.
B
Leucine is common in helices.
C
Methionine is also helix-favoring.
D
Correct. Proline's ring locks its backbone angle, and its amide nitrogen has no hydrogen to donate to the helix's hydrogen-bonding pattern.
TakeawayProline (rigid ring, no backbone N–H) and glycine (too flexible) break helices.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb22.