Figure 4:

(a-c) Comparisons of the Asp, Glu, and His pK_a’s from the GPU single-pH and CPU replica-exchange simulations(ΔpK_a(CPU) = GPU pK_a−CPU pK_a). (d-f) Comparisons of the single-pH results and experiment (ΔpK_a(Expt) = GPU pK_a−Expt pK_a). (g-i) Histograms of the convergence error estimates (δpK_a^run) obtained from the difference between the 2-ns and 1.5-ns pK_a’s. Asp26 of Thioredoxin (δpK_a^run =−0.34) falls off the plot. (j-l) Histograms of the statistical error estimates $\left(\delta \text{p}{K}_a^{\text{fit}}\right)$ from the pK_a fitting. The linked residues, Asp19/Asp21 in SNase and Asp10/Asp79 in RNase H, are excluded in the error estimates.