Figure 1
SDS–PAGE analysis of purified 6×His-tagged GKAI (a) and intact GKAI (b). (a) The bacterial lysate and purified recombinant fusion proteins were analyzed using 12% SDS–PAGE. Lane 1, molecular-mass markers (labelled in kDa); lane 2, lysate from non-induced cells; lane 3, lysate from induced cells; lane 4, pellets from induced cells; lane 5, supernatant (soluble fraction) from induced cells; lane 6, supernatant after heat treatment at 333 K for 20 min; lane 7, unbound fractions from the Ni–NTA agarose column; lane 8, purified 6×His-tagged GKAI. (b) The extra 17 amino acids including the 6×His tag were removed by thrombin digestion. The resulting molecular mass is approximately 2 kDa lower than that of the fusion protein. Lane 1, molecular-mass markers (labelled in kDa); lane 2, 6×His-tagged GKAI (∼58 kDa); lane 3, thrombin-digested GKAI (∼56 kDa). |