Figure 3.

Temperature dependence of the interaction of PriA and χ with SSB-Ct peptide (WP9) performed in low salt conditions (20 mM NaCl) in buffer C (10mM Cacodylate, pH 7.0, 25% glycerol)

(A) – van't Hoff plots of the dependences of K_obs on temperature for PriA (magenta squares) and χ (orange cirles).

(B) - Temperature dependences of thermodynamic parameters: ΔH_obs (PriA – magenta squares and χ - orange circles), ΔG°_obs (blue dashed and solid lines for PriA and χ, respectively) and TΔS°_obs (green dashed and solid lines for PriA and χ, respectively)

Solid lines (magenta for PriA and orange for χ ) through the experimental points in panels A and B represent global fits of the data to eqs 2–3 (see Materials and Methods) with the following parameters: K_obs,25°C=(3.4±0.6)×10⁶ M⁻¹, ΔH_obs,25°C = −17.6±0.2 kcal/mol and ΔCp_obs= −281±21 cal/mol deg for PriA and K_obs,25°C =(1.6±0.4)×10⁶ M⁻¹, ΔH_obs,25°C = −9.2±0.3 kcal/mol and ΔCp_obs= −143±21 cal/mol deg for χ. The dependences of ΔG°_obs and TΔS°_obs shown in panel B were simulated using ΔG°_obs=−RTlnK_obs and TΔS°_obs=ΔH_obs − ΔG°_obs.