ABSTRACT
Lipopolysaccharides (LPS) constitute one of the main components of the outer surface of gram-negative bacteria. The O-antigen polysaccharide (O-polysaccharide, O-specific side chain, O-chain), which is the polysaccharide part of LPS, generally has a regular structure and determines part of the immunospecificity of the cell. The reason why O-antigenic chains usually have regular structures is their mode of biosynthesis, in which preformed oligosaccharide blocks are transferred to a growing polymer chain. The length of the resulting chain varies considerably, and the distribution and the approximate length can be determined, e.g., by polyacrylamide gel electrophoresis with sodium dodecyl sulfate dispersing the lipopolysaccharide (SDS/PAGE). The core type of a certain species may be investigated chemically if at least part of the material contains few O-chains or none.
