THE CHEMICAL-STRUCTURE OF BACTERIAL-ENDOTOXIN IN RELATION TO BIOACTIVITY

Lipopolysaccharides (LPS) constitute the O-antigens and endotoxins of Gram-negative bacteria. Whereas both the polysaccharide and lipid port ion of LPS contribute to the pathogenic potential of this class of bac teria, it is the lipid component (lipid A) which determines die endoto xic properties of LPS. The primary structure of lipid A of various bac terial origin has been elucidated and Escherichia coli lipid A has bee n chemically synthesized. The biological analysis of synthetic lipid A partial structures proved that the expression of endotoxic activity d epends on a unique structural arrangement and conformation. Such analy ses have furthermore provided insight into the determinants required f or lipid A binding to and activation of human target cells. Present re search efforts aim at the molecular characterization of the specificit y, modulation and biomedical consequences of the interaction of lipid A with host cells.