Endotoxins are one of the most common pyrogenic (fever-inducing) impurities found in therapeutic protein preparations. They are negatively charged complex aggregates of lipopolysaccharides (LPS) present in the cell walls of gram-negative bacteria. Endotoxins are released by the shedding of viable cell walls or the breakdown of dead bacteria. The presence of even miniscule amounts of such pyrogens in purified proteins can cause major upheaval in downstream purification. In therapeutic proteins, such contaminants can lead to septic shock, tissue injury, and even death in certain cases. In research samples, endotoxins can hinder accurate data screening and immunological readouts. Therefore, it is essential that endotoxins are removed from all purified proteins, especially the ones destined for therapeutic uses such as drugs, injectables, and other pharmaceutical products.
Endotoxins are extremely thermally stable and insensitive to pH changes. This makes efficient and cost-effective removal of endotoxins very challenging. In fact, the removal of endotoxins is one of the most difficult tasks in downstream protein processing. Bio-Rad has provided a progressive selection of chromatography resins for process-scale purification of proteins for more than 50 years. This guide highlights the resins that have been successfully used for endotoxin removal.