MCQ – 65515

With help of the drug shown below, serotonin is synthesized from which of the following precursor amino acid? 

A.	Tyrosine.
B.	Tryptophan.
C.	Phenylalanine.
D.	Glycine.

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Correct Answer � B Explanation

Ans:B.)Tryptophan.

• Serotonin is synthesized from the essential amino acid tryptophan.
• The rate-limiting step is the conversion of the amino acid to 5-hydroxytrptophan by tryptophan hydroxylase. 
• This is then converted to serotonin by the aromatic L-amino acid decarboxylase which needs Pyridoxal Phosphate as a cofactor.