This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cofactor and prosthetic groups, Subject name: Biochemistry
[{'content': 'Tetrahydrobiopterin is required for the metabolism of \nSelect and explain. \nA. Alanine, B. Lysine, C. Phenylalanine, D. Serine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: THB is a cofactor for Aromatic amino acid (Tryptophan, Phenylalanine & Tyrosine) hydroxylases (See Fig)* Nitric acid synthase Serotonin synthesis Non-classical phenylketonuria types are due to defect in the synthesis or recycling of THB. Tetrahydrobiopterin (THB) is a nucleotide cofactor derived from Guanosine triphosphate.', 'role': 'assistant'}]