Effect of ion and surfactant choice on the recovery of a histidine-tagged protein from tobacco extract using foam fractionation

Tobacco plants can be used for the production of proteins for pharmaceutical applications. One of the most difficult and expensive tasks associated with this technology is isolating the product of interest from the hundreds of other chemicals found in tobacco. We describe a new recovery strategy in which the protein of interest is “tagged” with a histidine structure, which forms a complex with metal ions and a surfactant that will accumulate in the foamate of a foam fractionation step. His-gus, a histidine-tagged enzyme, was selectively recovered in the presence of two different surfactants and two different metal ions. The foam fractionation with N-∈-dodecylamido-N-α, N-α,-bis(carboxymethyl)-l-lysine surfactant and Ni²⁺ ions resulted in an average His-gus activity recovery value of 88% and an activity enrichment of 2.27. The performance of the recovery strategy without tobacco extract resulted in an average activity recovery value of 63.32% and an average activity enrichment value of 5.16, utilizing lauroylethylenediaminetriacetate surfactant and Ni²⁺ ions. It was shown that even though a majority of the native tobacco proteins are removed during the prefoaming step, the presence of tobacco extract does affect the recovery of His-gus.