Figure 3.

TDI-8304 selectively inhibits Pf20S. A) Dose-dependent inhibition of chymotryptic β5 subunits of Pf20S, human c-20S and i-20S. B) Time courses of inhibition of Pf20S β5 by TDI-8304 at indicated concentrations (nM). C) Plot of k_obs values obtained from the time course curves with varied TDI-8304 concentrations yields K_I^app = 1007 nM, K_i* = 89.6 nM and k_off = 0.0008 S⁻¹. D) TDI-8304 specifically inhibited Pf20S β5 but not β2 or β1, from being labeled by MV151, either in the absence of a Pf20S β2 specific inhibitor WLW-VS³ (top) or in the presence of WLW-VS (bottom).