Thermodynamic parameters for urea-induced unfolding equilibrium of PTPρwild-type and mutants.

Urea-induced unfolding equilibrium data were obtained at 10°C in 20 mM Tris/HCl, pH 7.5, containing 0.2 M NaCl and 200 µM DTT by measuring the relative fluorescence intensity at 338 nm. The free energy of unfolding from the native state to the intermediate (ΔGH2OI-N) and from the intermediate to the unfolded state (ΔGH2OU-I) were calculated from Eqn. 5. D50I-N and mI-N which are the midpoint and m value for the transition between native and intermediate state, respectively, and D50U-I and mU-I are the midpoint and m value for the transition between the intermediate and the unfolded state, respectively, were calculated from Eqn.6. Data are reported ± SE of the fit.