The biological activity of a recombinantly expressed (His)6-tagged peanut allergen (rAra h 1) is unaffected by endotoxin removal

The application of recombinant (His)6-tagged proteins in cell culture assays is associated with problems due to lipopolysaccharide (LPS) contamination. LPS stimulates cells of the immune system, thereby masking antigen-specific activation of T cells. Due to the affinity of LPS for histidine it is associated with difficulties to remove LPS from recombinant (His)6-tagged proteins. Here we describe that the Triton X-114 phase separation method can be used to remove LPS from (His)6-tagged proteins and that the recombinant proteins retain their biological activity.