Merck, L6529-1MG, Lipopolysaccharides from Escherichia coli O55:B5

Lipopolysaccharides (LPS) are complex glycolipids that contain several components. Enterobacteriaceae, such as E. coli, have highly conserved lipid A linked to the antigenic O-polysaccharide. Hydrophobic lipid A forms the outer most component that plays a role in the biological properties attributed to endotoxic LPS. A short core oligosaccharide (core OS) is found to be attached to lipid A. Enterobacteria contain an antigenic, repeat-structure O-polysaccharide (O-PS) attached to the distal core OS to form smooth LPS. O-PS in E. coli contains ∼170 distinct antigens that interact with the host immune system. Based on the core OS structures in E. coli, they have been designated K-12 and R1 to R4.