This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure & Function of Protein, Subject name: Biochemistry
[{'content': 'The immunoglobulin having highest molecular weight is: \nSelect and explain. \nA. IgG, B. IgM, C. IgE, D. IgA', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Ig MImmunoglobulins, a specialized group of proteins are mostly associated with gamma globulin fraction (on electrophoresis) of plasma proteins. All the Ig molecules consist of two identical heavy (H) chains and two identical (L) chains. Each have constant and variable regions. Humans have five classes of Ig- IgG, IgA, IgM, IgD and IgE. Out of these IgM is the largest composed of 5-Y shaped units held together by a J polypeptide chain. Due to its largest size, IgM cannot traverse blood vessels, hence it is restricted to the blood stream.', 'role': 'assistant'}]