Figure 4.

Compounds modulate the J-stimulated ATPase activity of TbHsp70s and HsHSPA8. Recombinant J-proteins (0.4 μM) and Hsp70 proteins (0.8 μM) alone and in the presence of the compounds at varying concentrations were incubated with 1 mM ATP for 1 h, and the released Pi was monitored at 595 nm using a direct colorimetric assay. Results are represented as fold change in the untreated J-stimulated Hsp70 ATPase activity (white bar) in relation to J-stimulated ATPase activity of the Hsp70s in the presence of compounds at varying concentrations (grey bars). Standard deviations were obtained from two replicate assays on three independent batches of proteins. Significant differences relative to the “no compound” reaction (Hsp70: J-protein; white bar) are indicated by * (p < 0.05) above the reaction.