scholarly journals t1-Noise eliminated dipolar heteronuclear multiple-quantum coherence solid-state NMR spectroscopy

2020 ◽  
Vol 22 (36) ◽  
pp. 20815-20828 ◽  
Author(s):  
Amrit Venkatesh ◽  
Xuechen Luan ◽  
Frédéric A. Perras ◽  
Ivan Hung ◽  
Wenyu Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quantum Correlation ◽  
Quantum Coherence ◽  
Pulse Sequences ◽  
Multiple Quantum ◽  
Heteronuclear Correlation ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Multiple Quantum Coherence ◽  
Nuclear Magnetic Resonance Pulse

t1-Noise eliminated (TONE) heteronuclear multiple quantum correlation (HMQC) solid-state nuclear magnetic resonance pulse sequences improve the sensitivity of 2D 1H{X} heteronuclear correlation experiments with X = 17O, 25Mg, 27Al and 35Cl.

scholarly journals t1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Amrit Venkatesh ◽  
Xuechen Luan ◽  
Frédéric Perras ◽  
Ivan Hung ◽  
Wenyu Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quantum Coherence ◽  
Pulse Sequence ◽  
Signal Amplitude ◽  
Spatial Proximity ◽  
Multiple Quantum ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Frequency Fluctuations ◽  
Multiple Quantum Coherence

<p>Heteronuclear correlation (HETCOR) spectroscopy is one of the key tools in the arsenal of the solid-state NMR spectroscopist to probe spatial proximity between two different nuclei and enhance spectral resolution. Dipolar heteronuclear multiple-quantum coherence (D-HMQC) is a powerful technique that can be potentially utilized to obtain <sup>1</sup>H detected 2D HETCOR solid-state NMR spectra of any NMR active nucleus. A long-standing problem in <sup>1</sup>H detected D-HMQC solid-state NMR experiments is the presence of <i>t</i><sub>1</sub>-noise which reduces sensitivity and impedes spectral interpretation. In this contribution, we describe novel pulse sequences, termed <i>t</i><sub>1</sub>-noise eliminated (TONE) D-HMQC, that suppress <i>t</i><sub>1</sub>-noise and can provide higher sensitivity and resolution than conventional D-HMQC. Monte-Carlo and numerical simulations confirm that <i>t</i><sub>1</sub>-noise in conventional D-HMQC primarily occurs because random MAS frequency fluctuations cause variations in the NMR signal amplitude from scan to scan, leading to imperfect cancellation of uncorrelated signals by phase cycling. The TONE D-HMQC sequence uses <sup>1</sup>H p-pulses to refocus the evolution of <sup>1</sup>H CSA across each recoupling block, improving the stability of the pulse sequence to random MAS frequency fluctuations. The <sup>1</sup>H refocusing pulses also restore the orthogonality of in-phase and anti-phase magnetization for all crystallite orientations, enabling the use of 90° flip-back or LG spin-lock trim pulses to reduce the intensity of uncorrelated signals. We demonstrate the application of these methods to acquire detected 2D <sup>1</sup>H-<sup>35</sup>Cl and <sup>1</sup>H-<sup>13</sup>C HETCOR spectra of histidine•HCl•H<sub>2</sub>O with reduced <i>t</i><sub>1</sub>-noise. To show generality, we also apply these methods to obtain 2D <sup>1</sup>H-<sup>17</sup>O spectra of 20%-<sup>17</sup>O fmoc-alanine and for the first time at natural abundance, 2D <sup>1</sup>H-<sup>25</sup>Mg HETCOR spectra of magnesium hydroxide. The TONE D-HMQC sequences are also used to probe <sup>1</sup>H-<sup>25</sup>Mg and <sup>1</sup>H-<sup>27</sup>Al proximities in Mg-Al layered double hydroxides and confirm the even mixing of Mg and Al in these materials.</p>

scholarly journals t1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Amrit Venkatesh ◽  
Xuechen Luan ◽  
Frédéric Perras ◽  
Ivan Hung ◽  
Wenyu Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quantum Coherence ◽  
Pulse Sequence ◽  
Signal Amplitude ◽  
Spatial Proximity ◽  
Multiple Quantum ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Frequency Fluctuations ◽  
Multiple Quantum Coherence

<p>Heteronuclear correlation (HETCOR) spectroscopy is one of the key tools in the arsenal of the solid-state NMR spectroscopist to probe spatial proximity between two different nuclei and enhance spectral resolution. Dipolar heteronuclear multiple-quantum coherence (D-HMQC) is a powerful technique that can be potentially utilized to obtain <sup>1</sup>H detected 2D HETCOR solid-state NMR spectra of any NMR active nucleus. A long-standing problem in <sup>1</sup>H detected D-HMQC solid-state NMR experiments is the presence of <i>t</i><sub>1</sub>-noise which reduces sensitivity and impedes spectral interpretation. In this contribution, we describe novel pulse sequences, termed <i>t</i><sub>1</sub>-noise eliminated (TONE) D-HMQC, that suppress <i>t</i><sub>1</sub>-noise and can provide higher sensitivity and resolution than conventional D-HMQC. Monte-Carlo and numerical simulations confirm that <i>t</i><sub>1</sub>-noise in conventional D-HMQC primarily occurs because random MAS frequency fluctuations cause variations in the NMR signal amplitude from scan to scan, leading to imperfect cancellation of uncorrelated signals by phase cycling. The TONE D-HMQC sequence uses <sup>1</sup>H p-pulses to refocus the evolution of <sup>1</sup>H CSA across each recoupling block, improving the stability of the pulse sequence to random MAS frequency fluctuations. The <sup>1</sup>H refocusing pulses also restore the orthogonality of in-phase and anti-phase magnetization for all crystallite orientations, enabling the use of 90° flip-back or LG spin-lock trim pulses to reduce the intensity of uncorrelated signals. We demonstrate the application of these methods to acquire detected 2D <sup>1</sup>H-<sup>35</sup>Cl and <sup>1</sup>H-<sup>13</sup>C HETCOR spectra of histidine•HCl•H<sub>2</sub>O with reduced <i>t</i><sub>1</sub>-noise. To show generality, we also apply these methods to obtain 2D <sup>1</sup>H-<sup>17</sup>O spectra of 20%-<sup>17</sup>O fmoc-alanine and for the first time at natural abundance, 2D <sup>1</sup>H-<sup>25</sup>Mg HETCOR spectra of magnesium hydroxide. The TONE D-HMQC sequences are also used to probe <sup>1</sup>H-<sup>25</sup>Mg and <sup>1</sup>H-<sup>27</sup>Al proximities in Mg-Al layered double hydroxides and confirm the even mixing of Mg and Al in these materials.</p>

Heteronuclear Multiple-Quantum Coherence NMR Spectroscopy of Im-cytC

1995 ◽  
Vol 28 (4) ◽  
pp. 641-650
Author(s):  
Weiping Shao ◽  
Xiaoling Huang ◽  
Gaohua Liu ◽  
Houming Wu ◽  
Wenxia Tang
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Coherence ◽  
Multiple Quantum ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Multiple Quantum Coherence

scholarly journals Spatially Selective Heteronuclear Multiple-Quantum Coherence Spectroscopy for Biomolecular NMR Studies

ChemPhysChem ◽  
2014 ◽  
Vol 15 (9) ◽  
pp. 1872-1879 ◽  
Author(s):  
Bharathwaj Sathyamoorthy ◽  
David M. Parish ◽  
Gaetano T. Montelione ◽  
Rong Xiao ◽  
Thomas Szyperski
Keyword(s):  
Quantum Coherence ◽  
Multiple Quantum ◽  
Nmr Studies ◽  
Biomolecular Nmr ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Coherence Spectroscopy ◽  
Multiple Quantum Coherence

scholarly journals Dependence of in vivo glutamine synthetase activity on ammonia concentration in rat brain studied by 1H - 15N heteronuclear multiple-quantum coherence-transfer NMR

1995 ◽  
Vol 311 (2) ◽  
pp. 681-688 ◽  
Author(s):  
K Kanamori ◽  
B D Ross ◽  
E L Kuo
Keyword(s):  
Quantum Coherence ◽  
Ammonia Concentration ◽  
Multiple Quantum ◽  
Blood Ammonia ◽  
Coherence Transfer ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Glutamine Synthesis ◽  
Gaba Synthesis ◽  
Multiple Quantum Coherence

The dependence of the in vivo rate of glutamine synthesis on the substrate ammonia concentration was studied in rat brain by 1H-15N heteronuclear multiple-quantum coherence-transfer NMR in combination with biochemical techniques. In vivo rates were measured at various steady-state blood and brain ammonia concentrations within the ranges 0.4-0.55 mumol/g and 0.86-0.98 mumol/g respectively, after low-rate intravenous 15NH4+ infusion (isotope chase). The rate of glutamine synthesis at steady state was determined from the change in brain [5-15N]glutamine levels during isotope chase, observed selectively through the amide proton by NMR, and 15N enrichments of brain glutamine and of blood and brain ammonia measured byN gas chromatography-MS. The in vivo rate (v) was 3.3-4.5 mumol/h per g of brain at blood ammonia concentrations (s) of 0.40-0.55 mumol/g. A linear increase of 1/v with 1/s permitted estimation of the in vivo glutamine synthetase (GS) activity at a physiological blood ammonia concentration to be 0.4-2.1 mumol/h per g. The observed ammonia-dependence strongly suggests that, under physiological conditions, in vivo GS activity is kinetically limited by sub-optimal in situ concentrations of ammonia as well as glutamate and ATP. Comparison of the observed in vivo GS activity with the reported in vivo rates of glutaminase and of gamma-aminobutyrate (GABA) synthesis suggests that, under mildly hyperammonaemic conditions, glutamine is synthesized at a sufficiently high rate to serve as a precursor of GABA, but glutaminase-catalysed hydrolysis of glutamine is too slow to be the sole provider of glutamate used for GABA synthesis.

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