Fig. 11.

Comparisons between mean helical contents obtained using AGADIR and those derived from CD measurements (a) and simulations (b), (c). In all three panels, if the AGADIR values were identical to the values along the abscissae, then the points would fall on the dashed lines shown in each of the three panels. AGADIR predictions were performed using default settings for the ionic strength and a temperature of 25˚C. This yields uniformly low helicity values for all eleven sequences. It also fails to capture the variation of intrinsic helicities with sequence. Similar trends, albeit lower helicity values are obtained by setting a salt concentration of 108 mM and temperature of 298.15 K. For the plot in panel (a), r = –0.07 and P = 0.85 and for the plot in panel (b), r = 0.23 and P = 0.49. In panel (a), the horizontal error bars are the differences between the helicity values inferred from the two sets of experiments. In panel (b), the horizontal error bars represent the standard error about the mean helicity that is calculated across at least 10 independent simulations for each sequence variant. Panel (c) shows a comparison of mean helicities derived from AGADIR versus those derived from the simulated ensembles for all 51 sequences shown in Figs 6 and 7. With five times more data than in panels (a) and (c), the data in panel (c) establish a consistent lack of correlation (r = 0.1 and P = 0.48) between AGADIR and ABSINTH-based mean helicities. These results are consistent with previous observations made on a different set of IDPs that show favorable comparisons between simulation results and experimental data and poor correlations when using AGADIR-based predictions (Das et al., 2012).