FIGURE 2.

The presence of ClpC1 or ClpX lowers the concentration of dipeptide activator needed to stimulate peptidase activity of ClpP1P2. Peptidase activity was measured with Ac-PKM-amc as described under “Experimental Procedures” but with varying concentrations of the activator Bz-Nva-Ile. Similar results were obtained with Bz-Leu-Leu (not shown). Where indicated, assay solutions also contained either ClpX or ClpC1, which was added in equimolar concentrations with the ClpP1P2 complex. Each point is the average of three measurements, which agreed within 5%. Similar results were obtained in at least three independent experiments. RFU, relative fluorescence.