What amino acid, if included in the middle of an alpha helix, would cause a bend in the alpha helix? (Hint: There is only one amino acid that would automatically lead to this effect.) What feature of this amino acid leads to the bend? Would including this amino acid destabilize the helix? Be sure to include non-covalent interactions in your answer.
On Internet I found the following: Proline residues--proline is the one amino acid without a primary alpha-amine (it is actually an imino acid). Because there is not free rotation about an amide formed with the proline imino group, it puts a kink (called a beta-turn) in the alpha-helix and disrupts it.
Not sure... I need more explanations...