This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
An amino acid which does not participate in alpha helix formation? 
Select and explain. 
A. Leucine, B. Methionine, C. Proline, D. Lysine
C: Proline
Answer: C: Proline 
Explanation: Proline can only be stably accommodated within the first turn of an α helix. When present elsewhere, proline disrupts the conformation of the helix, producing a bend.
 
Harper, Ed 30, Pg 38