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
Sakaguchi’s reaction is specific for 
Select and explain. 
A. Tyrosine, B. Proline, C. Arginine, D. Cysteine
C: Arginine
Answer: C: Arginine 
Explanation: Sakaguchi’s Test for Arginine : Free arginine or arginyl residues in proteins react with alpha-naphthol and alkaline hypobromite to give bright-red color. This is due to the guanidium group.
Reference: Vasudevan 7th  ed, pg 32