This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Fluoride inhibit enzyme of which ion? \nSelect and explain. \nA. Mg, B. Ca, C. Na, D. K', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Enolase is a dimeric metal-activated metallo-enzyme, which uses two magnesium ions per subunit: the strongly bound conformational ion and the catalytic ion that binds to the enzyme-substrate complex inducing catalysis.', 'role': 'assistant'}]