This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urea cycle, Subject name: Biochemistry
[{'content': 'All of the following are transaminated EXCEPT: \nSelect and explain. \nA. d- amino group of ornithine, B. a- amino group of proline, C. a- amino group of serine, D. a- amino group of cysteine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Only a amino group takes pa in transamination. Except:- d -amino group (non-a) of ornithine takes pa in transamination, where enzyme is OAT (Ornithine Amino Transferase). Out of the 20 amino acids, 3 amino acids do not take pa in transamination. Proline Lysine Threonine', 'role': 'assistant'}]