Homonuclear chemical shift correlation in rotating solids via RN?n symmetry-based adiabatic RF pulse schemes

Abstract

The efficacy of RN(nu) (n) symmetry-based adiabatic Zero-Quantum (ZQ) dipolar recoupling schemes for obtaining chemical shift correlation data at moderate magic angle spinning frequencies has been evaluated. RN(nu) (n) sequences generally employ basic inversion elements that correspond to a net 180 degrees rotation about the rotating frame x-axis. It is shown here via numerical simulations and experimental measurements that it is also possible to achieve efficient ZQ dipolar recoupling via RN(nu) (n) schemes employing adiabatic pulses. Such an approach was successfully used for obtaining (13)C chemical shift correlation spectra of a uniformly labelled sample of (CUG)(97) - a triplet repeat expansion RNA that has been implicated in the neuromuscular disease myotonic dystrophy. An analysis of the (13)C sugar carbon chemical shifts suggests, in agreement with our recent (15)N MAS-NMR studies, that this RNA adopts an Alpha-helical conformation.

A Combined Solid‐State NMR and X‐ray Crystallography Study of the Bromide Ion Environments in Triphenylphosphonium Bromides

“…15 N‐ 15 N chemical‐shift correlation experiments have enabled us to show the presence of canonical GC base pairs in this RNA 4. In addition, analysis of the observed 13 C chemical shifts for the sugar carbon atoms suggested that (CUG) 97 adopts an A‐form helix conformation with a C3′‐ endo sugar pucker and an anti conformation of the glycosidic torsion angle χ 5. Herein, we have explored the possibility of obtaining structural information directly by exploiting the dependence of inter‐ and intranucleotide 1 H– 1 H distances on RNA conformation.…”

“…13 C homonuclear isotropic chemical‐shift correlation spectra of a uniformly { 15 N, 13 C}‐labeled sample of (CUG) 97 obtained with different short proton spin diffusion mixing times are shown in Figure 2. The resonance assignments indicated are based on our recent studies 5. 14 The expected crosspeaks arising from direct or relayed magnetization transfers originating from sugar proton–sugar proton dipolar interactions and corresponding to intranucleotide proton–proton distances of <3.0 Å are seen.…”

Strategies for RNA Resonance Assignment by 13C/15N- and 1H-Detected Solid-State NMR Spectroscopy

“…Spin system-specific assignment of ribose resonances by conventional 13 C-detected ssNMR at MAS frequencies < 20 kHz can be achieved using a multitude of correlation schemes provided a satisfactory spectral linewidth is obtained. In the pioneering study by the Görlach group, mostly intra-ribose and partially ribose-base correlations were obtained using symmetry-based adiabatic ZQ recoupling experiments (Riedel et al, 2004). However, due to the low chemical shift resolution arising from limitations in sample preparation, spin system-specific assignment was not possible despite only three different nucleotides being present in the (CUG) 97 RNA.…”

Solid-state NMR spectroscopy for characterization of RNA and RNP complexes

“…In most cases, nucleotide-type selective labeling is necessary to overcome severe resonance overlap. Ribose carbons could be correlated through homonuclear 13 C, 13 C correlation experiments like symmetry-based recoupling [37], PDSD [38], DARR [39] or novel PAR [40] experiments; intranucleotide ribose-base connections could be obtained through PDSD correlation as well utilizing longer mixing time (Figure 1B). In 13 C, 13 C PDSD experiment after initial cross-polarization (CP) from 1 H to 13 C, 13 C chemical shifts are evolved during t 1 .…”