Isolation and Characterization of Lipopolysaccharides - Bacterial Pathogenesis: Methods and Protocols - page 2

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Isolation and Characterization of Lipopolysaccharides

Michael A. Apicella

Summary
Lipopolysaccharide (LPS) is the signature glycolipid isolated from almost all Gram-
negative bacteria. LPSs are well known for their ability to elicit the release of cytokines
from eukaryotic cells including macrophages, neutrophils, and epithelial cells. LPS can
be isolated free of contaminating nucleic acids and proteins by various techniques. In this
review, we outline approaches for the isolation and preparation of LPSs for structural
studies as well as preparation of very highly purified material for biological studies.
Methods are also provided for the analysis of the purity and the structural composition of
the LPSs. Finally, three methods for the isolation of lipid A are described.

Key Words: Lipopolysaccharide;

lipooligosaccharide; phenol; proteinase K;

SDS-PAGE; Lipid A.

1. Introduction
Lipopolysaccharides (LPSs) are a family of bacterial glycolipids which
consist of a lipid that has been designated lipid A and a carbohydrate component
of variable length. The lipid A molecules are frequently substituted with
phosphates, phosphoethanolamines, and sugars. The first description of LPS
was in 1941, when Shear determined that the component of the Serratia
marcescens cell wall responsible for tumor-destroying activity was composed
of a polysaccharide and a lipid (1) . He was also the first to designate this
material “lipopolysaccharide.” LPS is embedded in the external layer of the
bacterial outer membrane and is linked through 2-keto-3-deoxyoctulosonic acid
to a carbohydrate component that extends into the surrounding environment (2) .