Determination of Global Structure from Distance and Orientation Constraints in Biological Solids Using Solid-State NMR Spectroscopy

We report the results from a new solid-state NMR experiment, DANTE−REDOR, which can
determine global secondary structure in uniformly (13C,15N)-enriched systems by simultaneously measuring
distance and orientation constraints. Following a heteronuclear spin-pair selection using a DANTE pulse
train, the magnitude and orientation of the internuclear dipole vector, within the chemical shift anisotropy
(CSA) frame of the observed nucleus, are determined by tracking the dephasing of individual spinning
sidebands under magic angle spinning. The efficacy of the experiment is demonstrated by measuring the
imidazole side-chain orientation in U-[13C6,15N3]-l-histidine·HCl·H2O.