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: Biochemistry
[{'content': 'At physiological pH, carboxy terminal of peptide is \nSelect and explain. \nA. Positive charged, B. Negative charged, C. Neutral, D. Infinitely charged', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In ion-exchange chromatography, proteins interact with the stationary phase by charge-charge interactions. Proteins with a net positive charge at a given pH will tightly adhere to beads with negatively charged functional groups such as carboxylates or sulfates (cation exchangers).\n\xa0\nHarper, Ed 30, Pg 27', 'role': 'assistant'}]