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
Flexibility of protein depends on 
Select and explain. 
A. Glycine, B. Tryptophan, C. Phenylalanine, D. Histidine
A: Glycine
Answer: A: Glycine 
Explanation: Glycine is one among the commonest amino acids found in protein structure. Being small and non-polar, glycine  is  mostly  present in  the interior structure of  protein. 
Satyanarayana, Ed 3, Pg 302