This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Biochemistry
[{'content': 'The enzyme catalyzing the production of orotidylic acid is? \nSelect and explain. \nA. Aspayl transcarbamoylase, B. Dihydro orotase, C. Dihydro orotate dehydrogenase, D. Orotate phosphoribosyl transferase', 'role': 'user'}, {'content': "Answer: D \nExplanation: In the de novo synthesis of pyrimidines, the enzyme aspayl transcarbamoylase catalyses the combination of carbamoyl phosphate and aspaate to form carbamoyl aspaate. Dihydro orotase catalyses the production of dihydro orotic acid. Dihydro orotate dehydrogenase catalyses the production of orotic acid from dihydro orotic acid. Orotate phosphoribosyl transferase is the enzyme catalyzing the synthesis of orotidylic acid (Orotidine 5'-monophosphate). Ref: Textbook of Biochemistry, D. M. Vasudevan & Sreekumari S, 4th edition, page 394.", 'role': 'assistant'}]