ABSTRACT
Lipopolysaccharides (LPS) of gram-negative bacteria are composed of three genetically and structurally distinct regions: the O-antigenic polysaccharide (O-specific chain); the core oligosaccharide; and a lipophilic portion, termed lipid A, which anchors the LPS molecule to the bacterial outer membrane. From the very beginning of structural research on endotoxin, a number of research groups performed studies on lipid A obtained from various bacterial sources with the goal of defining the structural elements carrying or modifying the biological activity. These efforts were based on the idea that knowledge of the lipid A structure is an absolute prerequisite for an understanding of the molecular mechanisms operative during endotoxic effects. Since the development of soft ionization methods for the mass spectrometric analysis of complex biomolecules in the early 1980s, these methods have been used for the structural determination of LPS and of its partial structures.
