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Accurate Determination of 1 H‐ 15 N Dipolar Couplings Using Inaccurate Settings of the Magic Angle in Solid‐State NMR Spectroscopy
Author(s) -
Xue Kai,
Mühlbauer Max,
Mamone Salvatore,
Sarkar Riddhiman,
Reif Bernd
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201814314
Subject(s) - magic angle , magic angle spinning , solid state nuclear magnetic resonance , anisotropy , deuterium , dipole , spinning , nuclear magnetic resonance spectroscopy , rotor (electric) , spectroscopy , physics , analytical chemistry (journal) , computational physics , nuclear magnetic resonance , materials science , chemistry , atomic physics , molecular physics , optics , quantum mechanics , chromatography , composite material
Magic‐angle spinning (MAS) is an essential ingredient in a wide variety of solid‐state NMR experiments. The standard procedures to adjust the rotor angle are not highly accurate, resulting in a slight misadjustment of the rotor from the magic angle ( θ R L =tan - 12 ) on the order of a few millidegrees. This small missetting has no significant impact on the overall spectral resolution, but is sufficient to reintroduce anisotropic interactions. Shown here is that site‐specific 1 H‐ 15 N dipolar couplings can be accurately measured in a heavily deuterated protein. This method can be applied at arbitrarily high MAS frequencies, since neither rotor synchronization nor particularly high radiofrequency field strengths are required. The off‐MAS method allows the quantification of order parameters for very dynamic residues, which often escape an analysis using existing methods.