Identifying H–N proximities in solid-state NMR using 14N overtone irradiation under fast MAS

O’Dell, Luke A.; He, Rongliang; Pandohee, Jessica

doi:10.1039/c3ce40967h

Cited by 46 publications

(75 citation statements)

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“…[10] Ad etailed discussion of the appearance of the 14 Npowderpatterns and how they are influenced by the NMR interactions can be found in ar eview by O'Dell. [3] An umber of methods have been explored for the acquisition of 14 NSSNMR spectra, including direct observation of 14 NNMR signals from single crystals, [13] anisotropically oriented samples, [14,15] overtone 14 NNMR spectroscopy, [16][17][18] and 14 N magic-angle spinning (MAS) NMR by using probes with precisely tuned rotor angles, [10] slow spinning speeds, [19] and specialized pulse sequences. [20] Nuclear quadrupole resonance (NQR)h as also been widely used to investigate many types of nitrogen systems.…”

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confidence: 99%

¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

et al. 2016

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N ultra-wideline solid-state NMR (SSNMR) spectra were obtained for 16 naturally occurring amino acids and four related derivatives by using the WURST-CPMG (wideband, uniform rate, and smooth truncation Carr-Purcell-Meiboom-Gill) pulse sequence and frequency-stepped techniques. The N quadrupolar parameters were measured for the sp nitrogen moieties (quadrupolar coupling constant, C , values ranged from 0.8 to 1.5 MHz). With the aid of plane-wave DFT calculations of the N electric-field gradient tensor parameters and orientations, the moieties were grouped into three categories according to the values of the quadrupolar asymmetry parameter, η : low (≤0.3), intermediate (0.31-0.7), and high (≥0.71). For RNH moieties, greater variation in N-H bond lengths was observed for systems with intermediate η values than for those with low η values (this variation arose from different intermolecular hydrogen-bonding arrangements). Strategies for increasing the efficiency of N SSNMR spectroscopy experiments were discussed, including the use of sample deuteration, high-power H decoupling, processing strategies, high magnetic fields, and broadband cross-polarization (BRAIN-CP). The temperature-dependent rotations of the NH groups and their influence on N transverse relaxation rates were examined. Finally, N SSNMR spectroscopy was used to differentiate two polymorphs of l-histidine through their quadrupolar parameters and transverse relaxation time constants. The strategies outlined herein permitted the rapid acquisition of directly detected N SSNMR spectra that to date was not matched by other proposed methods.

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Section: Introductionmentioning

confidence: 99%

¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

et al. 2016

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“…Nonetheless, NMR methodologies for the acquisition of 14 N spectra in the solid state have been developed over the past 15 years for both static and spinning samples . Techniques involving overtone irradiation have been explored . The use of signal enhancement by DNP has also been evaluated .…”

Section: Introductionmentioning

confidence: 99%

Self‐Assembly of DNA and RNA Building Blocks Explored by Nitrogen‐14 NMR Crystallography: Structure and Dynamics

2020

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The isotopic enrichment of nucleic acids with nitrogen-15 is often carried out by solid-phase synthesis of oligonucleotides using phosphoramidite precursors that are synthetically demanding and expensive. These synthetic challenges, combined with the overlap of chemical shifts, explain the lag of nitrogen-15 NMR studies of nucleic acids behind those of proteins. For the structural characterization of DNA and RNA-related systems, new NMR methods that exploit the naturally occurring 99.9 % abundant nitrogen-14 isotope are therefore highly desirable. In this study, we have investigated nitrogen-14 spectra of selfassembled quartets based on the nucleobase guanine in the solid state by means of magic-angle spinning NMR spectro-scopy. The network of dipolar proton-nitrogen couplings between neighboring stacked purine units is probed by 2D spectra based on 1 H! 14 N! 1 H double cross-polarization. Interplane dipolar contacts are identified between the stacked G quartets. The assignment is supported by density functional theory (DFT) calculations of the anisotropic chemical shifts and quadrupolar parameters. The experimental spectra are fully consistent with internuclear distances obtained in silico. Averaging of chemical shifts due to internal motions can be interpreted by semiempirical calculations. This method can easily be extended to synthetic G quartets based on nucleobase or nucleoside analogs and potentially to oligonucleotides.[a] Dr.

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“…The main limitation of this method is its low sensitivity, with the overtone transition providing only a small fraction of the signal attainable from the fundamental transitions. Very recently, several authors have investigated the possibility of observing these overtone signals indirectly via more amenable nuclei such as 1 H, and this approach shows much promise [13,14]. In this contribution, we explore the possibility of using dynamic nuclear polarisation (DNP) to enhance directly and indirectly detected 14 N OT signals.…”

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“…For impregnated solids with long 1 H T1 relaxation times, and which contain sufficient proton density, spin diffusion can transport enhanced 1 H polarisation from the 1 H nuclei at the surface over μm distances into the bulk crystalline phase, after which cross polarisation can be used to transfer the enhanced polarisation to another nucleus such as 13 C [22][23][24]. Recent studies have already applied CP pulse sequences to transfer DNP-enhanced 1 H polarisation to the central transitions of half-integer quadrupolar nuclei such as 17 O [25] and 27 Al [26], while DNP enhancement in the indirect detection of the 14 N fundamental transitions has also been explored using 13 C labelled samples [27].…”

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“…Herein, we use this state-of-the-art approach to demonstrate that cross polarisation from 1 H nuclei directly to the 14 N overtone transition is possible under MAS conditions, and results in high quality powder patterns that can be accurately simulated to extract 14 N isotropic chemical shifts and quadrupolar parameters. Furthermore, we show that DNP enhancements can allow 1 H- 14 N OT and 13 C-14 N OT correlation spectra to be obtained from natural abundance samples in a matter of hours, providing an attractive method for observing C-N correlations from unlabelled samples.…”

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Dynamic nuclear polarisation enhanced¹⁴N overtone MAS NMR spectroscopy

Rossini

Emsley

O’Dell

2014

Phys. Chem. Chem. Phys.

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Dynamic nuclear polarisation (DNP) has been used to obtain magic angle spinning (14)N(OT) (nitrogen-14 overtone) solid-state NMR spectra from several model amino acids, with both direct and indirect observation of the (14)N(OT) signal. The crystalline solids were impregnated with biradical solutions of organic liquids that do not dissolve the crystalline phase. The bulk phase was then polarized via(1)H spin diffusion from the highly-polarized surface (1)H nuclei, resulting in (1)H DNP signal enhancements of around two orders of magnitude. Cross polarisation from (1)H nuclei directly to the (14)N overtone transition is demonstrated under magic angle spinning, using a standard pulse sequence with a relatively short contact time (on the order of 100 μs). This method can be used to acquire (14)N overtone MAS powder patterns that match closely with simulated line shapes, allowing isotropic chemical shifts and quadrupolar parameters to be measured. DNP enhancement also allows the rapid acquisition of 2D (14)N(OT) heteronuclear correlation spectra from natural abundance powder samples. (1)H-(14)N(OT) HETCOR and (13)C-(14)N(OT) HMQC pulse sequences were used to observe all single-bond H-N and C-N correlations in histidine hydrochloride monohydrate, with the spectra obtained in a matter of hours. Due to the high natural abundance of the (14)N isotope (99.6%) and the advantages of observing the overtone transition, these methods provide an attractive route to the observation of C-N correlations from samples at natural isotopic abundance and enable the high resolution measurement of (14)N chemical shifts and quadrupolar interaction parameters.

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Identifying H–N proximities in solid-state NMR using 14N overtone irradiation under fast MAS

Cited by 46 publications

References 34 publications

¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

Self‐Assembly of DNA and RNA Building Blocks Explored by Nitrogen‐14 NMR Crystallography: Structure and Dynamics

Dynamic nuclear polarisation enhanced¹⁴N overtone MAS NMR spectroscopy

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Identifying H–N proximities in solid-state NMR using 14N overtone irradiation under fast MAS

Cited by 46 publications

References 34 publications

14N Solid‐State NMR Spectroscopy of Amino Acids

14N Solid‐State NMR Spectroscopy of Amino Acids

Self‐Assembly of DNA and RNA Building Blocks Explored by Nitrogen‐14 NMR Crystallography: Structure and Dynamics

Dynamic nuclear polarisation enhanced14N overtone MAS NMR spectroscopy

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¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

¹⁴N Solid‐State NMR Spectroscopy of Amino Acids

Dynamic nuclear polarisation enhanced¹⁴N overtone MAS NMR spectroscopy