Purification of recombinant M. tuberculosis BCAT. E. coli BL21(DE3) CodonPlus-RIL cells were induced with IPTG and prepared as described in the Materials and Methods section. The cell lysate was separated by centrifugation into pellet (P) and supernatant (S) fractions. The supernatant was loaded onto an Ni2+-charged metal ion affinity column and flow through (F), 80 mM imidazole (W), and 800 mM imidazole (E) fractions were collected. Aliquots of each fraction were analysed on a 10% polyacrylamide gel under reducing conditions. Lane (M) contains molecular mass markers (units in kDa).