FIG. 3.

SDS-PAGE analysis of His₆-tagged DraSO expression and purification by affinity chromatography. E. coli BL21-CodonPlus(DE3)-RIL transformed with plasmid pET-draSO (A) and TP1000 (ΔmobAB) transformed with plasmid pTrcHis-draSO (B) were grown and subjected to induction of gene expression at 22°C. The His₆-tagged protein was detectable after nickel affinity chromatography of the cleared protein extracts (lanes 1 and 4) and was recovered in 0.25 mM imidazole fractions (lanes 3 and 5) after washing in 10 mM imidazole (lane 2). The molecular mass, about 43.0 kDa, was determined with reference to molecular weight standards (lanes M₁ and M₂).