Figure 4.

Improvement of structure determination using the eRFDR-approach. (A) Correlation between bidirectional (red) as well as unidirectional (orange) exact-RFDR restraints (depicted on the structure in Figure 4B) and the corresponding distances read out from the crystal structure (2NUZ). Distance errors are employed as described for eNORA2 previously²⁵. The R² value of the fit is 0.96 for distances smaller than 5.5 Å. Values for larger distances are less accurate. The deviation of the short distance HN18↔HN19 (leftmost point) is likely due to molecular dynamics in this loop²⁶ (also compare Figure S10). (B) Depiction of the obtained eRFDR-restraints, color-coded as red (bidirectional) and orange (uni-directional). (C) Ensemble of the 10 lowest-energy structures from 300 calculated structures using 112 unambiguous conventional upper-distance restraints in addition to angular restraints. For determining the upper distance limit of conventional restraints, the restraints were grouped with respect to the ratio of cross and diagonal peak. Proton distances corresponding to large cross-peak intensity ratios were treated as close (5 Å), medium ratios as 7.5 Å, and small ratios as far (9 Å), in addition to angular restraints. (D) Structure calculation based on 47 conventional RFDR upper distance restraints (for peaks with insufficient resolution in their diagonal), 35 unidirectional eRFDR-restraints and 30 bidirectional eRFDR-restraints.