Figure 4.

Substituted 4,5′-bithiazoles act as ATP competitive catalytic inhibitors of human DNA topoisomerase IIα. (A) Results of the topo IIα ATPase assay. Compound 1 almost fully inhibited the human topo IIα-mediated ATP hydrolysis at 125 μM. The graph shown is representative of two independent experiments. (B) Results of the competitive topo IIα ATPase assay. (C) Microscale thermophoresis (MST) experimental binding curve of compound 1. In the MST experiment, we kept the concentration of the human topo IIα ATPase domain labeled molecule constant, while the concentration of unlabeled compound 1 was varied between 0.03 and 1000 μM.