Figure 1.

Purification and oligomeric state of isolated S. flexneri VapC^D7A toxin. (a) Fractions of the purified protein were analysed on 15% SDS–PAGE. Lane 1, molecular-weight marker (labelled in kDa); lane 2, elution from the Ni–NTA affinity column; lane 3, final protein sample after size-exclusion chromatography. The theoretical molecular mass of the VapC monomer is 14.8 kDa. (b) Analysis of the oligomeric state of isolated VapC using size-exclusion chromatography. The arrows at the top indicate the elution volumes of proteins of known mass (given in kDa). The elution volume of VapC^D7A (13.5 ml) suggests that the molecule is present as a dimer in solution (∼30 kDa).