Lipopolysaccharides antigenic properties

Lipopolysaccharides are the dominant surface feature of the outer membrane of gram-negative bacteria such as Escherichia coli and Salmonella ty-phimurium. These molecules are prime targets of the antibodies produced by the vertebrate immune system in response to bacterial infection and are therefore important determinants of the serotype of bacterial strains (serotypes are strains that are distinguished on the basis of antigenic properties). The lipopolysaccharides of S. typhimurium contain six fatty acids bound to two... 

Lipopolysaccharides form a class of macromolecules unique to Gramnegative bacteria. They are of great compositional and structural diversity, and yet, they are built up according to a common architectural principle. With few exceptions, lipopolysaccharides are biologically highly active substances. Lipopolysaccharides have been called endotoxins because of their toxic properties. Due to the antigenic properties which they confer to the surface of the bacterial cell, they are also termed O antigens. 

The mitogenic properties of E. coli are destroyed by mild alkaline treatment of the lipopolysaccharide, whereas the antigenic properties are unchanged. It was also shown that binding of the polysaccharide portion of the lipopolysaccharide to antigenic receptors on the surface of B cells is necessary for triggering off a primary immune response to lipopolysaccharides. 

Abstract Lipopolysaccharides are the major components on the surface of most Gram-negative bacteria, and recognized by immune cells as a pathogen-associated molecule. They can cause severe diseases like sepsis and therefore known as endotoxins. Lipopolysaccharide consists of lipid A, core oligosaccharide and O-antigen repeats. Lipid A is responsible for the major bioactivity of endotoxin. Because of their specific structure and amphipathic property, purification and analysis of lipopolysaccharides are difficult. In this chapter, we summarize the available approaches for extraction, purification and analysis of lipopolysaccharides. 

Amano K. An Interesting Property of O-Antigen Polysaccharide in lipopolysaccharide Cross-talk between Lipopolysaccharides of Helicobacter pylori and host cells through lewis blood group antigens. Trends Glycosci Glycotechnol 14 (2002) 105-114. 

In a series of papers, Westphal and his collaborators have reported on many different strains, using phenol-extracted lipopolysaccharides the physical properties were fully described, the antigenic and serological properties were reported, and some of the sugar compositions were given. The product of Escherichia coli 08 was described in the most detail the material was composed of 26 % of lipide and 74% of polysaccha-... 

Lipopolysaccharides.— Recent reviews have dealt with the compositions and the structures of bacterial lipopolysaccharides/ the serological properties, chemistry, and genetics of the O antigens from E. coli, the enterobacterial common antigen, the involvement of lipids in the biosynthesis of lipopolysaccharides, and the binding of bacteriophages to O antigens. ... 

KDO has chemical properties similar to those of neuraminic acid as it has a carboxylate group, a 3-deoxy group, and a similar biosynthesis (see Chapter 10). The monosaccharide composition, sequence, and linkages, along with the position of attachment of phosphate and ethanolamine pyrophosphate substituted onto the heptose residues of the core polysaccharide have been determined [53-58] and are shown in Fig. 9.16C. The fatty acids in the lipopolysaccharide participate in the formation of a lipid bilayer for the outer membrane. The carbohydrate is hydrophilic and is located on the outer faces of the lipid bilayer membrane. The O-antigen polysaccharides and other capsular polysaccharides are attached to position-4 of the next to last monosaccharide residue, a-D-glucopyranose of the core polysaccharide. 

The lipopolysaccharides are heat stable, highly antigenic and exceedingly toxic. They are responsible for many of the cell-surface properties of gram-negative bacteria (Carter ei al., 1965). 

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