104 



INTRODUCTION TO IMMUNOCHEMICAL SPECIFICITY 



The first important step in the study of endotoxins was the de- 

 velopment by Boivin (Boivin and Mesrobeanii, 1933) of a method 

 of extracting them with trichloracetic acid. Boivin reported that the 

 endotoxins of a number of gram-negative bacteria consisted mainly 

 of polysaccharide and lipid. 



Modern knowledge of the chemistry of endotoxins derives mainly 

 from the work of Morgan (1937, 1940, 1941, 1942) and Goebel 

 (1945), who showed that endotoxins are complexes containing phos- 

 phorylated polysaccharide and protein. Further work by these and 

 other workers on the degradation products of the endotoxins revealed 

 that they have the make-up shown in Table 8-1 (Westphal and 

 Liideritz, 1954). 



TABLE 8-1 

 The Endotoxin Complex of the Cell Wall of Grain-Xegative Bacteria'' 



Lipopolysaccharide-Protein-Lipid-Coniplex 



Lipopolysaccharide 

 (iindegraded poly 

 saccharide) 



Phosphorylated 

 polysaccharide 



Conjugated protein 



Lipid A 



Lipid B 



(easily split off) 



Protein 



» Westphal and Liideritz, 1954. 



It appears that the lipid A component is responsible for many of 

 the toxic effects of these complex substances ( Schmidt, Eichenberger, 

 and Westphal, 1958; Westphal, 1960). All the preparations of this 

 component examined from various enterobacteria seem to be similar 

 or perhaps identical (Westphal, 1960), containing about 20 per cent 

 D-glucosamine, 7-8 per cent phosphoric ester, 50 per cent long-chain 

 fatty acid (including hydroxy-fatty acids), and a peptide side chain 

 containing serine and dicarboxy amino acids. 



