Biochemistry General 039a2b9b Which of the following is not true about tryptophan? A Involved in niacin synthesis B Involved in serotonin synthesis C Involved in melatonin synthesis D It is a non essential amino acid. High-Yield Explanation Tryptophan is an essential aminoacid. It is used in the synthesis of Melatonin, serotonin and niacin.