Relationship between Particle Size and Biological Activity of E. coli Boivin Endotoxin*

Many investigators have tried unsuccessfully to demonstrate that a specific chemical structure is responsible for the toxic action of bacterial endotoxins. Practically all of the protein (or peptide) and lipid constituents of the endotoxin molecule may be removed without affecting significantly its biological activities, and the carbo- hydrate moiety loses toxicity after it is depolymerized by even mild acid hydrolysis (1-4). Recent studies have also shown that toxicity does not depend upon the presence of the polysaccharide side chains that give the endotoxin its O-antigenic specificity (5).