Comparison of methods for 14 N- 1 H recoupling in 14 N- 1 H HMQC MAS NMR

H-detected N heteronuclear multiple-quantum coherence (HMQC) magic-angle-spinning (MAS) NMR experiments performed at fast magic-angle spinning (≥50 kHz) are finding increasing application, e.g., to pharmaceuticals. Of importance to the efficacy of these techniques is the recoupling technique applied...

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Bibliographic Details
Published inJournal of magnetic resonance (1997) Vol. 352; p. 107459
Main Authors Tatman, Ben P, Modha, Haritosh, Brown, Steven P
Format Journal Article
LanguageEnglish
Published United States 01.07.2023
Subjects
Dipeptides
Nitrogen
Nuclear Magnetic Resonance, Biomolecular - methods
Pharmaceutical Preparations
NMR
Recoupling
Rotary resonance recoupling
H
TRAPDOR
Dipolar coupling
N
MAS
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Summary:H-detected N heteronuclear multiple-quantum coherence (HMQC) magic-angle-spinning (MAS) NMR experiments performed at fast magic-angle spinning (≥50 kHz) are finding increasing application, e.g., to pharmaceuticals. Of importance to the efficacy of these techniques is the recoupling technique applied to reintroduce the H- N dipolar coupling. In this paper, we compare, by experiment and 2-spin density matrix simulations, two classes of recoupling scheme: first, those based on n = 2 rotary resonance, namely R and spin-polarisation inversion SPI-R , and the symmetry based SR4 method and, second, the TRAPDOR method. Both classes require optimisation depending on the magnitude of the quadrupolar interaction, and thus there is a compromise choice for samples with more than one nitrogen site, as is the case for the studied dipeptide β-AspAla that contains two nitrogen sites with a small and large quadrupolar coupling constant. Considering this, we observe better sensitivity for the TRAPDOR method, though noting the marked sensitivity of TRAPDOR to the N transmitter offset, with both SPI-R and SR4 giving similar recoupling performance.
ISSN:1096-0856