Resolution Enhancement in SEA XLOC for Heteronuclear NMR Long‐Range Correlation

Gyöngyösi, Tamás; Kövér, Katalin E.; Sørensen, Ole W.

doi:10.1002/open.201900136

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…The MFA experiments that have been created in this way are, e.g., 1 H, 1 H-TOCSY/TOCSY, 1 H, 13 C-HSQC/ pure shift HSQC, 1 H, 13 C-HSQC/HSQC-TOCSY, and 1 H, 13 C-HSQC(F 2 -coupled)/HSQC, where for the latter dual experiment the F 2 -coupled spectrum is recorded first due to the intrinsically higher sensitivity of the decoupled version and that reduction in sensitivity takes place for the second FID due to translational diffusion of the molecules during acquisition of the first FID. Concatenation of SEA X-LOC, which can distinguish between two-and three-bond correlations based on different multiplet widths in the indirect dimension, 323,324 with H2OBC, 271 thus sharing the relaxation delay, d 1 , can provide complete correlation maps, as shown for an O-methylated and O-sulfated trisaccharide with a complex substitution pattern. 325 The concatenation approach was further extended to give a SEA XLOC-HMBC-H2OBC experiment for resonance assignments based on heteronuclear one-bond and long-range correlations.…”

Section: Chemicalmentioning

confidence: 99%

“…Concatenation of SEA X-LOC, which can distinguish between two- and three-bond correlations based on different multiplet widths in the indirect dimension, , with H2OBC, thus sharing the relaxation delay, d 1 , can provide complete correlation maps, as shown for an O -methylated and O -sulfated trisaccharide with a complex substitution pattern . The concatenation approach was further extended to give a SEA XLOC-HMBC-H2OBC experiment for resonance assignments based on heteronuclear one-bond and long-range correlations .…”

Section: Nmr Experiments For Resonance and Sequence Assignmentsmentioning

confidence: 99%

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Primary Structure of Glycans by NMR Spectroscopy

Fontana

Widmalm

2023

Chem. Rev.

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Glycans, carbohydrate molecules in the realm of biology, are present as biomedically important glycoconjugates and a characteristic aspect is that their structures in many instances are branched. In determining the primary structure of a glycan, the sugar components including the absolute configuration and ring form, anomeric configuration, linkage(s), sequence, and substituents should be elucidated. Solution state NMR spectroscopy offers a unique opportunity to resolve all these aspects at atomic resolution. During the last two decades, advancement of both NMR experiments and spectrometer hardware have made it possible to unravel carbohydrate structure more efficiently. These developments applicable to glycans include, inter alia, NMR experiments that reduce spectral overlap, use selective excitations, record tilted projections of multidimensional spectra, acquire spectra by multiple receivers, utilize polarization by fast-pulsing techniques, concatenate pulse-sequence modules to acquire several spectra in a single measurement, acquire pure shift correlated spectra devoid of scalar couplings, employ stable isotope labeling to efficiently obtain homo-and/or heteronuclear correlations, as well as those that rely on dipolar cross-correlated interactions for sequential information. Refined computer programs for NMR spin simulation and chemical shift prediction aid the structural elucidation of glycans, which are notorious for their limited spectral dispersion. Hardware developments include cryogenically cold probes and dynamic nuclear polarization techniques, both resulting in enhanced sensitivity as well as ultrahigh field NMR spectrometers with a 1 H NMR resonance frequency higher than 1 GHz, thus improving resolution of resonances. Taken together, the developments have made and will in the future make it possible to elucidate carbohydrate structure in great detail, thereby forming the basis for understanding of how glycans interact with other molecules.

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Section: Chemicalmentioning

confidence: 99%

Section: Nmr Experiments For Resonance and Sequence Assignmentsmentioning

confidence: 99%

Primary Structure of Glycans by NMR Spectroscopy

Fontana

Widmalm

2023

Chem. Rev.

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“…identify two-bond proton-carbon correlations based on the observation that most 2 J CH have a negative sign [20][21][22][23] . However, both methods have notable limitations.…”

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confidence: 99%

Unequivocal identification of two-bond heteronuclear correlations in natural products at nanomole scale by i-HMBC

et al. 2023

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HMBC is an essential NMR experiment for determining multiple bond heteronuclear correlations in small to medium-sized organic molecules, including natural products, yet its major limitation is the inability to differentiate two-bond from longer-range correlations. There have been several attempts to address this issue, but all reported approaches suffer various drawbacks, such as restricted utility and poor sensitivity. Here we present a sensitive and universal methodology to identify two-bond HMBC correlations using isotope shifts, referred to as i-HMBC (isotope shift detection HMBC). Experimental utility was demonstrated at the sub-milligram / nanomole scale with only a few hours of acquisition time required for structure elucidation of several complex proton-deficient natural products, which could not be fully elucidated by conventional 2D NMR experiments. Because i-HMBC overcomes the key limitation of HMBC without significant reduction in sensitivity or performance, i-HMBC can be used as a complement to HMBC when unambiguous identifications of two-bond correlations are needed.

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“…What is needed for that is suitable replacement of the p/2 excitation pulse in each module (vide infra). The modules we concatenate include HMBC [5] for long-range correlation, SEA XLOC [6] yielding a spectrum similar to HMBC but with two-and three-bond distinction, and 2BOB/ H2OBC [7] delivering an H2BC [8] and a one-bond correlation spectrum similar to HSQC. [9] Two different pools of magnetization are involved in the experiments, namely 1 H magnetization not attached (the I pool) or attached (the IS pool) to 13 C, respectively, and the BANGO pulse sequence element [10] effectively discriminates between them.…”

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confidence: 99%

NORD: NO Relaxation Delay NMR Spectroscopy

Nagy

Kövér

Sørensen³

2021

Angewandte Chemie

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The novel concept of NORD (NO relaxation delay) NMR spectroscopy is introduced. The idea is to design concatenated experiments in a way that the magnetization used in the first relaxes toward equilibrium during the second and vice versa, thus saving instrument time. Applications include complete well-resolved 1 H-1 H and 1 H-13 C one-bond and long-range correlation maps of an 80 mM solution of a trisaccharide recorded in less than two minutes and hydrocortisone with extensive spectral overlap.

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Resolution Enhancement in SEA XLOC for Heteronuclear NMR Long‐Range Correlation

Cited by 6 publications

References 10 publications

Primary Structure of Glycans by NMR Spectroscopy

Primary Structure of Glycans by NMR Spectroscopy

Unequivocal identification of two-bond heteronuclear correlations in natural products at nanomole scale by i-HMBC

NORD: NO Relaxation Delay NMR Spectroscopy

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