Endotoxin is a lipopolysaccharide (LPS) found in the cell wall of gram negative bacteria. It is continuously shed from the cell wall and released when the bacterium dies. Endotoxin is a contaminant in plasmid preparations and bacterial protein expression that must be removed from research samples to avoid toxicity or interference in cell-based assays.
When using E. coli or other gram negative bacteria for recombinant proteins, endotoxin is likely to contaminate the plasmid preparation and the expressed protein. Before conducting additional assays, such as immunologic readouts or developing a manufacturing process, this complex lipopolysaccharide (LPS) should be removed. While intact bacteria can be captured using a 0.2 µm filter, the LPS can be more challenging. An effective method of removal of the negatively charged LPS is to use a substrate with a positive charge. We offer Acrodisc® Units with Mustang® E Membrane for effective removal of endotoxin.