Preparation of tritiated lipopolysaccharides from Escherichia coli K12

Tritiated lipopolysaccharide (LPS) from E. coli K12 was prepared by coupling [3H]ethanolamine to the LPS core residue ketodeoxyoctonate (KDO) via activation of its carboxylic function with N-hydroxysuccinimide or N-hydroxy-sulfosuccinimide. Specific activities of 1.5 microCi/mg and 9 microCi/mg were obtained, respectively. Experiments comparing the activity of native and derivatized LPS suggested that the preparation of the radiolabelled LPS did not alter the structural properties of E. coli K12 LPS. This probe will be useful for studying the interactions between LPS and proteins.