This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'Which of the following amino acids have side chains that are negatively charged under physiological conditions? \nSelect and explain. \nA. Aspaic acid, B. Histidine, C. Tyrosine, D. Serine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The side chains of the acidic amino acids, aspaic acid and glutamic acid, are negatively charged above pH 3; in their ionized state, they are often referred to as aspaate and glutamate. Asparagine and glutamine are, respectively, the amides of aspaic acid and glutamic acid. Ref: Voet Fundamentals of Biochemistry 4th Edition Pg no 82.', 'role': 'assistant'}]