FIGURE 3.
Measurement of the intraholoenzyme KD for His-tagged P protein and PRNA (or C domain) as a function of ionic strength. The observed KD for wild-type holoenzyme complex (•) and the C domain–P protein complex (○) were determined in 50 mM Tris-HCl (pH 8), 10 mM MgCl2, 10 mM imidazole, and 0.1–800 mM KCl at room temperature. The ionic strength was determined as described in Equation 3. Equation 1, derived from the model shown in Scheme 1 ▶, was fit to the data. The results of these fits are listed in Table 1 ▶.