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Endotoxins are biologically active structural components of the outer cell membrane of all Gram-negative bacteria. Endotoxins are invariably associated with Gram-negative bacteria whether the organisms are pathogens or not. Although the term “endotoxin” is occasionally used to refer to any cell-associated bacterial toxin, it is usually reserved to refer to the endotoxin/LPS complex associated with the outer membrane of Gram-negative bacteria, such as E. coli, Salmonella, Shigella, Pseudomonas, Neisseria, Haemophilus, and other leading pathogens.
Endotoxins are very stable molecules in comparison to proteins, with their biologically active part surviving extremes of temperature and pH. In general, baking of contaminated glassware is the recommended procedure to destroy endotoxin/LPS. However, it is not always practical to bake proteins and heat-sensitive bioreagents since these will be destroyed as well.
Ever since the endotoxin testing has become more important, the Limulus Amebocyte Lysate (LAL) assay is used to detect endotoxin associated with Gram-negative bacteria. Currently, Cambrex offers four LAL methodologies licensed by the FDA. The first, PYROGENT®, is referred as the gel clot method, and is based on the fact that LAL clots in the presence of endotoxin. The kinetic turbidimetric method, PYROGENT-5000®, is a quantitative LAL method that utilizes the rate of gelation to determine endotoxin content. The third (QCL-1000®) and the fourth (Kinetic-QCL®) methods are chromogenic assays, which produce a yellow product that is linearly related to the endotoxin concentration.
New method for endotoxin detection
Besides the LAL assays, PyroGene is a new method for the endotoxin detection offered by Cambrex. The endotoxin detection is based on the activation of recombinant Factor C, and is not derived from the animal blood. Unlike LAL, PyroGene does not contain crab-derived proteins that bind to other substances, eliminating the false positive reactions, such as glucans can react with some LAL to cause false-positive results.
To remove endotoxin
EndoTrap products are the new affinity matrix for the efficient removal of bacterial endotoxin from aqueous solutions containing low or high molecular weight substances. Based on ligand technology derived from a bacteriophage, the high affinity of EndoTrap to endotoxin enables the efficient capturing of endotoxin, even at very low concentrations. The efficiency of endotoxin removal is partly dependent on buffering conditions. So, the product range is divided into two classes of endotoxin removal columns, EndoTrap Blue and EndoTrap Red. This provides optimal endotoxin removal under a wide range of conditions.
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