Figure 1.

SDS–PAGE showing the purification of spMCAT. Lane 1, supernatant of sonicated E. coli containing spMCAT before loading onto the Ni²⁺-affinity column; lane 2, flowthrough of the sample, showing binding of spMCAT onto the column; lane 3, flowthrough from the washing buffer containing 25 mM imidazole; lane 4, spMCAT eluted from the Ni²⁺-affinity column using 300 mM imidazole; lane 5, spMCAT eluted from the Superdex 200 column, which was used for protein crystallization trials. Lane M, molecular-mass marker (labelled in kDa).