<prompt> None Not seen in alpha helix ?AlanineLeucineProlineIsoleucine  <response>: Ans. is c i.e., Proline Proline is never found in a-helix as it has imino group -NH not amino -N112.Thus it cannot provide hydrogen for hydrogen bonding, the major stabilizing force of a-helix.Glycine also tends to disrupt a-helix; because of its high flexibility and small size it often induces bends in a-helix. 