FIG. 4.

SDS-PAGE characterization of P. aeruginosa PAO1 GluRS (A), the three subunits of the heterotrimeric AdT (B), and AspRS (C) overproduced in P. aeruginosa ADD1976 and purified by affinity chromatography on Ni-NTA. (A) Lanes: 1, protein standard; 2 to 8, wash with 30 mM imidazole; 9 to 10, GluRS elution with 90 mM imidazole. (B) Lanes: 1 to 9, amidotransferase elution with 100 mM imidazole, after an initial wash with 30 mM imidazole; 10, protein standard. (C) Lanes: 1, protein standard; 2, AspRS elution with 85 mM imidazole, after an initial wash with 30 mM imidazole; 3 and 4, contaminant and pure AspRS, respectively, removed after Superdex 200 chromatography. Numbers indicate the molecular mass (in kilodaltons) of protein standards. The gels (8% polyacrylamide) are stained with Coomassie blue.