Figure 1.
Log kobs vs. [urea] plots for the folding and unfolding of wild-type barnase and the mutants TS16, TG16, and NA58. kobs is the unfolding rate constant at high urea concentration and the refolding at low urea concentration. Note how the unfolding data closely parallel each other and the refolding rate constants are nearly identical in 0 M urea. Yet, there are differences in stability of up to 2.1 kcal⋅mol−1 (Inset). NA58 is one of the few mutants of barnase for which the ratio of folding and extrapolated unfolding rate constants in water is close to the independently measured value.