Lipopolysaccharide, E. coli O55:B5 (LPS)

Lipopolysaccharide (LPS) structures may be generally described as three linked regions. The first structural feature is the lipid component Lipid A, primarily responsible for the effects of endotoxin. Linked to Lipid A is the core antigen or R polysaccharide, a short chain of sugars including 2-keto 3-deoxyoctonate (KDO). The third structural feature is attached to the core polysaccharide and is more elaborate, containing up to 40 repeating subunits of 3 to 5 sugars, referred to as the O antigen, O side chain or O polysaccharide. Variations in the composition of the O antigen account for the species specific antibody responses. Lipid A, acting alone or as a component of LPS, is a potent modulator of the mammalian immune response.  The presence of Lipid A or LPS in mammalian macrophages or endothelial cells triggers a signaling cascade leading to the secretion of pro-inflammatory cytokines and nitric oxide. LPS also acts as a B cell mitogen. Differences in Lipid A fatty acid side chain structures may be responsible for variations of the known effects on the immune system.

Source:
Lipopolysaccharide from E. coli 055:85

Analysis:
2-Keto-3-deoxyoctonate (KDO): 2.9%
Phosphate: 2.5%
Protein: 1.4%
Nucleic acid: 0.7%
Endotoxin: 4.3Eu/ng

Reconstitution:
LPS is dispersable in aqueous solvents at concentrations of 1mg/ml. To achieve suspension in water, heating to about 50°C with intermittent vortexing or sonication is generally recommended Allow ample time for dispersion to occur. The use of 0.5% triethylamine aids in dispersion. Triethylamine is very basic and may be neutralized with Tris HCI to avoid hydrolysis of the fatty acid chains. It is recommended that this material be stored at 4°C prior to and following reconstitution.

Storage and Stability:
Lyophilized and reconstituted products are stable for 6 months after receipt at 4°C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at 4°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.