Residual Dipolar Couplings - Use for Structure Elucidation

The lack of long-range restraints has hindered the precise and accurate structure determination of nucleic acids for a long time. The isotopic enrichment mostly improved the accuracy of local geometry without a pronounced influence on the overall shape. However, 

Since NMR data may reflect the conformational averaging resulting from a substantial flexibility of DNA/RNA fragments, the parameters of the ensemble of structures obtained by MD refinement and experimental NMR restraints can display internal inconsistency. James and coworkers developed a method to determine the family of structural conform-ers and their populations based on NMR data [83]. This approach applies multiple-copy refinement with floating weights, which better reflects the conformational dynamics of nucleic acids. 

In general, the results of NMR structure refinement should be independent of the applied force field and refinement tools and reflect primarily the experimental restraints. At 

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