The EndoTrap Endotoxin Removal System is used in our lab for the preparation of aqueous single chain and Fab antibody samples to be used in animal studies. Although avoidance of endotoxin contamination by clean protein production and purification methods are preferred, for preparations derived from bacteria strains this is not always feasible. We recently switched from the BioVintage EndoClean removal kit (based on a two-phase extraction principle) to the Profos EndoTrap System that removes endotoxins through affinity chromatography. You can either purchase the kits as ready-to-use columns or as resin slurry to customize columns individually. Both options include equilibration and regeneration buffers. A unique advantage to the Profos system is the inclusion of a clear manual with detailed product descriptions, such as the composition of buffers. Profos offers 2 kits, EndoTrap Blue and EndoTrap Red, which differ in their buffer compatibilities. EndoTrap Blue requires buffers enriched with calcium, while EndoTrap Red is compatible with PBS and EDTA-containing buffers.
The endotoxin-binding ligand is immobilized covalently on beaded agarose, ensuring only minimal leakage of the ligand. Two reasons why we switched from the two-phase EndoClean system (BioVintage) were 1) protein samples were easily contaminated through interface disturbance while transferring the layer containing the protein and 2) consistent low protein recovery rates. Compared to the BioVintage system, I have found the handling of the EndoTrap columns from Profos straightforward and easier to use. For example, the kit is not temperature sensitive and the binding capacity is 2x106 EU/ml with a recovery rate of over 90% (advantageous when working with precious protein samples).
I also like the endotoxin compendium that is available on the company's website (www.profos.de). It compiles all necessary information about endotoxins in a concise way and is quite helpful for novices to endotoxin contamination. The only downside I found was ordering, as the company is in Germany and the price is listed in Euro, requiring conversion of cost to US dollars. In addition, payments could only be made by check or credit card (not with a PO number), which was very inconvenient. Once the order had been placed, the delivery was very quick. The price might appear quite high, but should be weighed against the value of a reliable endotoxin removal kit preventing the loss of a significant amount of protein.
Charlotte Berndt
Research Assistant
Department of Chemistry
The Scripps Research Institute