Biochemistry Proteins and Amino Acids 91945f21 Serotonin is: A 5 Hydroxy tryptophan B 5 Hydroxy tryptamine C 5 Carboxy tryptamine D 5 Carboxy tryptophan High-Yield Explanation Ans. B. 5 Hydroxytryptamine5 Hydroxy Tryptophan is decarboxylated by Aromatic aminoacid decarboxylase to form 5 Hydroxytryptamine or Serotonin. Coenzyme is PLP.