VieB is a non-competitive inhibitor. A Lineweaver-Burk Plot was generated using the previously described phosphotransfer assay over a range of VieA-His6 (2, 4, and 8 μM) and wild-type VieB (0, 4, 8, and 12 μM) concentrations. VieA-His6 phosphorylated with 32P (P-VieA-His6) was quantified by radioautography. These data represent the average velocity of three replicates (0, 4 and 12 μM VieB) and four replicates (8 μM VieB). V = velocity.