Ultrahigh‐Resolution Backbone Structure of Perdeuterated Protein GB1 Using Residual Dipolar Couplings from Two Alignment Media

NMR dipolar couplings can be measured for weakly aligned proteins and are sensitive probes of their structure and dynamics. The combination of fixed geometry and 1H–1H couplings alone from two alignment media provides access to ultrahigh-resolution structures. The apparent precision, as measured by independent cross-validation and structure comparison, is comparable to that available from high-resolution X-ray crystallography.