This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
All the following are features of Endotoxins Except 
Select and explain. 
A. Lipopolysaccharides, B. Proteins, C. Heat stable, D. No enzymic action
B: Proteins
Answer: B: Proteins 
Explanation: Distinguishing features of exotoxins and endotoxinsExotoxinsEndotoxinsProteinsLipopolysaccharidesHeat-labileHeat StableActively secreted by cells; diffuse into surrounding mediumForm pa of the cell wall; do not diffuse into surrounding mediumReadily separable from cultures by physical means such as filtrationObtained only by cell lysisAction often enzymicNo enzymatic actionSpecific pharmacological effect for each exotoxinEffect nonspecific; action common to all endotoxinsSpecific tissue affinitiesNo specific tissue affinityActive in very minute dosesActive only in very large dosesHighly antigenicWeakly antigenicAction specifically neutralized by antibodyNeutralisation by antibody ineffectiveRef: Ananthanarayan; 7th edition; Page no: 67