FIGURE 3.

Catalytic activity of G737V and P473L TOP2 proteins. The catalytic activity of wild-type, G737V, and P473L proteins were compared using ATP-dependent relaxation of 200 ng of pUC18. The amount of added Top2p (in nanograms) is indicated above each lane. The lane labeled pUC18 is plasmid DNA treated in the absence of Top2p. All assays were carried out at least three times, and the results shown are representative of all assays that were performed. A, relaxation activity of P473L compared with wild-type Top2. Complete relaxation of pUC18 was seen at 20 ng of wild-type protein, and 140 ng of P473L protein. B, relaxation activity of G737V protein. Complete relaxation was seen for both wild-type and G737V proteins at 25 ng of added protein.