This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
What changes the conformation of alpha helix in collagen 
Select and explain. 
A. Methionine, B. Proline, C. Alanine, D. Tyrosine
B: Proline
Answer: B: Proline 
Explanation: Ans. (b) ProlineRef: Harper's Biochemistry, 30th ed. pg. 141, 298-99* Proline is the amino acid which changes the conformation of the alpha helix in collagen due to the nature of proline having a cyclical structure. It also forms the ends of the beta sheets in the secondary structures.