This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Diphtheria toxin acts by \nSelect and explain. \nA. Inhibiting acetyl choline release, B. Inhibiting glucose transpo, C. Inhibiting levels of cyclic AMP, D. Inhibiting protein synthesis', 'role': 'user'}, {'content': "Answer: D \nExplanation: The diphtheria toxin acts by inhibiting protein synthesis. Specifically, a fragment B heparin binding and fragment A inhibits polypeptide chain elongation in the presence of nicotinamide adenine dinucleotide by inactivating the elongation factor EF-2. It has a special affinity for ceain tissues such as the myocardium, adrenals and nerve endings. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 240", 'role': 'assistant'}]