Figure 1.

All three force fields predict NAc-ORF6_CTR is disordered but only the a03ws and C36m force fields predict that NAc-ORF6_CTR undergoes proline cis/trans isomerization. (A) cis-proline (pink) and trans-proline (green) conformations with the positions of C^γ and C^β indicated. (B) Definition of the ζ (gray) and ψ (purple) dihedral angles used as CVs to enhance proline cis/trans isomerization. (C) R_g probability distributions were calculated using kernel density estimates to compare the a03ws run 1 (orange), a99SB-disp (red), and C36m (blue) ensembles. Ensemble-averaged R_g are shown for each system. The associated error represents the standard deviation between the first and second halves of the analyzed trajectories. The experimental SAXS data and error (standard deviation from the Guinier analysis) are shown in gray. (D) Probability distributions for the ω angle about the Q56-P57 peptide bond in the a03ws run 1 (orange), a99SB-disp (red), and C36m (blue) ensembles. The thickness of the gray distribution represents the uncertainty. The cis-P57 populations are displayed for each system and the error represents the standard deviation between the first and second halves of the analyzed trajectories.