LPS is a highly potent lipopolysaccharide produced from E. coli O113:H10. This endotoxin has been purified to eliminate residual intrinsic proteins and nucleic acids. Potency of this product, in endotoxin units (EU), is determined to be at least 10EU per ng LPS, or 10e6 EU per mg LPS.

Endotoxins have been used to study the relationship between infection and the host innate immune system.  In humans, endotoxins have been shown to correlate with changes in cytokines, hormones and inflammatory makers, such as TNF, IL-6, cortisol, epinephrine, serum amyloid A and C-reactive protein.

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.

Analysis:
2-Keto-3-deoxyoctonate (KDO)4: 1.8%
Nucleic acid: 0.41%
There are no detectable protein bands on a colloidal gold blot transferred from SDS-PAGE.

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.

Storage and Stability:
Lyophilized powder may be stored at 4°C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at 4°C. Reconstituted product is stable for 6 months 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.