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Zhan H, Gao C, Huang C, Lin X, Huang Y, Chen Z. Efficient determination of scalar coupling networks by band selective decoupled 2D NMR spectroscopy. Anal Chim Acta 2023; 1277:341682. [PMID: 37604618 DOI: 10.1016/j.aca.2023.341682] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/17/2023] [Accepted: 07/31/2023] [Indexed: 08/23/2023]
Abstract
Scalar (J) couplings constitute one of vital features observed in NMR spectroscopy and show valuable information for molecular structure elucidation and conformation analysis. However, existing J coupling measurement techniques are generally confined by the concerns of resolution, SNR, and experimental efficiency. Herein, we exploit an efficient 2D NMR protocol to deal with the above concerns by enabling rapid, sensitive, and high-resolution J coupling extraction. This protocol delivers full-resolved pure shift 2D absorption-mode spectroscopy to gain great convenience for efficient coupling measurements on overcrowded NMR signals. Resulting from band selective signal evolution, this protocol ensures high signal intensity with full magnetization preservation to meet the demand on probing low-concentration samples. This protocol focuses on accessing coupling information between specific two coupled spin families, and it is not applicable to all possible spin systems. Besides, it adopts echo-train selective refocusing acquisition to accelerate pure shift 2D J-edited implementations into pseudo-2D acquisition, and thus holding the experimental efficiency similar to conventional SERF experiments. Therefore, this study presents a promising tool for efficient extraction of J coupling networks, and takes an important step for coupling measurement techniques with wide applications on molecular conformation elucidation and stereochemical configuration analysis.
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Affiliation(s)
- Haolin Zhan
- Department of Biomedical Engineering, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei 230009, China
| | - Cunyuan Gao
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Chengda Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Xiaoqing Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
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2
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Mishra SK, Suryaprakash N. Pure shift edited NMR methodologies for the extraction of Homo- and heteronuclear couplings with ultra-high resolution. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 136-137:1-60. [PMID: 37716754 DOI: 10.1016/j.pnmrs.2023.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 01/20/2023] [Accepted: 02/01/2023] [Indexed: 09/18/2023]
Abstract
The scalar couplings that result in the splitting of the signals in the NMR spectrum arise due to the interaction of the nuclear spins, whereby the spin polarization is transmitted through chemical bonds. The interaction strengths depend inter alia on the number of consecutive chemical bonds intervening between the two interacting spins and on the molecular conformation. The pairwise interaction of many spins in a molecule resulting in a complex spectrum poses a severe challenge to analyse the spectrum and hence the determination of magnitudes and signs of homo- and heteronuclear couplings. The problem is more severe in the analysis of 1H spectra than the spectra of most of the other nuclei due to the often very small chemical shift dispersion. As a consequence, the straightforward analysis and the accurate extraction of the coupling constants from the 1H spectrum of a complex spin system continues to remain a challenge, and often may be a formidable task. Over the years, the several pure shift-based one-dimensional and two-dimensional methodologies have been developed by workers in the field, which provide broadband homonuclear decoupling of proton spectra, removing the complexity but at the cost of the very informative scalar couplings. To circumvent this problem, several one-dimensional and two-dimensional NMR experiments have been developed for the determination of homonuclear and heteronuclear couplings (nJHX, where n = 1,2,3) while retaining the high resolution obtained by implementing pure shift strategies. This review attempts to summarize the extensive work reported by a large number of researchers over the years for the accurate determination of homo- and heteronuclear scalar couplings.
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Affiliation(s)
- Sandeep Kumar Mishra
- Department of Physics and NMR Research Centre, Indian Institute of Science Education and Research, Pune 411008, India.
| | - N Suryaprakash
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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3
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Najac C, Boer VO, Kan HE, Webb AG, Ronen I. Improved detection limits of J-coupled neurometabolites in the human brain at 7 T with a J-refocused sLASER sequence. NMR IN BIOMEDICINE 2022; 35:e4801. [PMID: 35833462 PMCID: PMC9788253 DOI: 10.1002/nbm.4801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 07/02/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
In a standard spin echo, the time evolution due to homonuclear couplings is not reversed, leading to echo time (TE)-dependent modulation of the signal amplitude and signal loss in the case of overlapping multiplet resonances. This has an adverse effect on quantification of several important metabolites such as glutamate and glutamine. Here, we propose a J-refocused variant of the sLASER sequence (J-sLASER) to improve quantification of J-coupled metabolites at ultrahigh field (UHF). The use of the sLASER sequence is particularly advantageous at UHF as it minimizes chemical shift displacement error and results in relatively homogenous refocusing. We simulated the MRS signal from brain metabolites over a broad range of TE values with sLASER and J-sLASER, and showed that the signal of J-coupled metabolites was increased with J-sLASER with TE values up to ~80 ms. We further simulated "brain-like" spectra with both sequences at the shortest TE available on our scanner. We showed that, despite the slightly longer TE, the J-sLASER sequence results in significantly lower Cramer-Rao lower bounds (CRLBs) for J-coupled metabolites compared with those obtained with sLASER. Following phantom validation, we acquired spectra from two brain regions in 10 healthy volunteers (age 38 ± 15 years) using both sequences. We showed that using J-sLASER results in a decrease of CRLBs for J-coupled metabolites. In particular, we measured a robust ~38% decrease in the mean CRLB (glutamine) in parietal white matter and posterior cingulate cortex (PCC). We further showed, in 10 additional healthy volunteers (age 34 ± 15 years), that metabolite quantification following two separate acquisitions with J-sLASER in the PCC was repeatable. The improvement in quantification of glutamine may in turn improve the independent quantification of glutamate, the main excitatory neurotransmitter in the brain, and will simultaneously help to track possible modulations of glutamine, which is a key player in the glutamatergic cycle in astrocytes.
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Affiliation(s)
- Chloé Najac
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Vincent O. Boer
- Danish Research Centre for Magnetic ResonanceCopenhagen University Hospital HvidovreHvidovreDenmark
| | - Hermien E. Kan
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Andrew G. Webb
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Itamar Ronen
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
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4
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Pure shift NMR and DFT methods for revealing long-range heteronuclear couplings. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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5
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Yang C, Chen J, Zeng Q, Luo Y, Chen Z, Lin Y. Simultaneous acquirement of pure shift 2D homonuclear correlation spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 339:107229. [PMID: 35512441 DOI: 10.1016/j.jmr.2022.107229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/08/2022] [Accepted: 04/21/2022] [Indexed: 06/14/2023]
Abstract
Two dimensional homonuclear correlation spectra like COSY, TOCSY and NOESY are classic two-dimensional spectra for analyzing coupling networks and delivering structural information of molecules. Two main challenges of the homonuclear correlation spectra are resolution and efficiency. Because of the complexity of the molecular structure and the effect of scalar coupling, spectral resolution is still difficult to meet the demand, and a higher resolution is needed to improve the quality of the homonuclear correlation spectrum. On the other hand, although some homonuclear correlation spectra are often used together (such as COSY and TOCSY), they are generally sampled separately, and as the number of sampling points in the indirect dimension increases, experiment time increases dramatically. Here, we propose a scheme that can be used to simultaneously obtain indirect dimension pure shift COSY and TOCSY or indirect dimension pure shift COSY and NOESY to improve the resolution of them, while reducing the sampling time and improving the efficiency.
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Affiliation(s)
- Chuang Yang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Jinyong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Qing Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yao Luo
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
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Simultaneous determination of multiple coupling networks by high-resolution 2D J-edited NMR spectroscopy. Anal Chim Acta 2021; 1185:339055. [PMID: 34711310 DOI: 10.1016/j.aca.2021.339055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/10/2021] [Accepted: 09/11/2021] [Indexed: 11/24/2022]
Abstract
J coupling constitutes an important NMR parameter for molecular-level composition analysis and conformation elucidation. Dozens of J-based approaches have been exploited for J coupling measurement and coupling network determination, however, they are generally imposed to insufficient spectral resolution to resolve crowded NMR resonances and low measurement efficiency that a single experiment records one J coupling network. Herein, we propose a general NMR method to collect high-resolution 2D J-edited NMR spectra, which are characterized with advantages of pure absorptive lineshapes, decoupled chemical shift dimension, as well as eliminated axial peaks, thus facilitating J coupling partner assignments and J coupling constant measurements. More meaningfully, this protocol allows simultaneous determination of multiple coupling networks for highly efficient multiplet analyses via addressing multiple protons within one single experiment. Additionally, another variant is proposed for high-resolution applications under adverse magnetic field conditions. Therefore, this study provides a useful NMR protocol for configurational and structural studies with extensive applications in chemistry, biology, and material science.
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7
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Wu D, Carillo KJ, Shie JJ, Yu SSF, Tzou DLM. Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy. Molecules 2021; 26:molecules26092643. [PMID: 33946512 PMCID: PMC8124291 DOI: 10.3390/molecules26092643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022] Open
Abstract
For decades, high-resolution 1H NMR spectroscopy has been routinely utilized to analyze both naturally occurring steroid hormones and synthetic steroids, which play important roles in regulating physiological functions in humans. Because the 1H signals are inevitably superimposed and entangled with various JH–H splitting patterns, such that the individual 1H chemical shift and associated JH–H coupling identities are hardly resolved. Given this, applications of thess information for elucidating steroidal molecular structures and steroid/ligand interactions at the atomic level were largely restricted. To overcome, we devoted to unraveling the entangled JH–H splitting patterns of two similar steroidal compounds having fully unsaturated protons, i.e., androstanolone and epiandrosterone (denoted as 1 and 2, respectively), in which only hydroxyl and ketone substituents attached to C3 and C17 were interchanged. Here we demonstrated that the JH–H values deduced from 1 and 2 are universal and applicable to other steroids, such as testosterone, 3β, 21-dihydroxygregna-5-en-20-one, prednisolone, and estradiol. On the other hand, the 1H chemical shifts may deviate substantially from sample to sample. In this communication, we propose a simple but novel scheme for resolving the complicate JH–H splitting patterns and 1H chemical shifts, aiming for steroidal structure determinations.
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Affiliation(s)
- Danni Wu
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan; (D.W.); (K.J.C.); (J.-J.S.); (S.S.-F.Y.)
| | - Kathleen Joyce Carillo
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan; (D.W.); (K.J.C.); (J.-J.S.); (S.S.-F.Y.)
- International Graduate Program, SCST, Academia Sinica, Nankang, Taipei 11529, Taiwan
- The Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 30013, Taiwan
| | - Jiun-Jie Shie
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan; (D.W.); (K.J.C.); (J.-J.S.); (S.S.-F.Y.)
| | - Steve S.-F. Yu
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan; (D.W.); (K.J.C.); (J.-J.S.); (S.S.-F.Y.)
| | - Der-Lii M. Tzou
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan; (D.W.); (K.J.C.); (J.-J.S.); (S.S.-F.Y.)
- Department of Applied Chemistry, National Chia-Yi University, Chia-Yi 60004, Taiwan
- Correspondence:
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Dong X, Zeng Q, Zhan C, Chen J, Yang C, Chen Z, Lin Y. A simple data post-processing method for axial peaks free 2D PSYCHEDELIC NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 325:106938. [PMID: 33636634 DOI: 10.1016/j.jmr.2021.106938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/07/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
Homonuclear scalar coupling plays an important role in the elucidation of molecular structure and dynamics. However, complex multiplets due to 1H-1H scalar coupling splittings complicate the assignment of peaks in overcrowded spectral regions. Although many methods focusing on disentangling couplings have been proposed in recent years, some defects like intense axial peaks and dispersive components still exist. Herein, a simple data post-processing method based on the interleaved acquisition mode PSYCHEDELIC (Pure Shift Yielded by CHirp Excitation to DELiver Individual Couplings) is designed to acquire absorption-mode 2D J spectrum while eradicating axial peaks. This approach provides a high resolution and pure absorptive spectrum, permitting unambiguous and accurate measurement of scalar coupling constants involving a given proton.
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Affiliation(s)
- Xi Dong
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Qing Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Chaoqun Zhan
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Jinyong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Chuang Yang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518057, China.
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9
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Zeng Q, Zhan C, Dong X, Chen J, Chen Z, Lin Y. Unambiguous and accurate measurement of scalar coupling constants through a selective refocusing NMR experiment. Anal Chim Acta 2021; 1159:338429. [PMID: 33867039 DOI: 10.1016/j.aca.2021.338429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/14/2021] [Accepted: 03/15/2021] [Indexed: 01/06/2023]
Abstract
Scalar coupling plays an important role in the analysis of molecular structure and dynamics. A great number of nuclear magnetic resonance (NMR) selective refocusing experiments, such as 2D G-SERF and PSYCHEDELIC, were developed to extract scalar coupling constants involving a selected proton from overlapped spectra. However, intense axial peaks occur in this type of experiments, leading to possible ambiguity in the assignment of spectral peaks and subsequent accurate measurement of 1H-1H scalar coupling constants. Here, a method based on selective coherence transfer and PSYCHEDELIC module is designed to acquire absorption-mode selective refocusing spectrum while suppressing intense axial peaks. Therefore, unambiguous and accurate measurement of scalar coupling constants involving the selectively excited proton can be achieved. The performances of the proposed method are demonstrated on several samples.
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Affiliation(s)
- Qing Zeng
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Chaoqun Zhan
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Xi Dong
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Jinyong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Zhong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
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10
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Zeng Q, Chen J, Zhan C, Lin Y, Chen Z. Fully Exploiting the Power of 2D NMR J-Resolved Spectroscopy. Anal Chem 2020; 92:6893-6899. [PMID: 32338887 DOI: 10.1021/acs.analchem.9b05441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool that enables one to study molecular properties and interactions. Homonuclear couplings provide valuable structural information but are often difficult to disentangle in crowded 1H NMR spectra where complex multiplets and signal overlap commonly exist. Multidimensional NMR experiments push the power of NMR to a new level by providing better signal dispersion. Among them, 2D J-resolved spectroscopy is widely used for multiplet analysis and the measurement of scalar coupling constants. Here, we present a new 2D J-resolved method, CASCADE, through which easier multiplet analysis and unambiguous measurement of specific coupling constants can be achieved at the same time, fully exploiting the power of 2D J-resolved spectroscopy. It is expected that this method may replace a conventional 2D J experiment in many cases, facilitating structural and configurational studies as well as chemical and biological analyses.
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Affiliation(s)
- Qing Zeng
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Electronic Science, Xiamen University, Xiamen 361005, P. R. China
| | - Jinyong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Electronic Science, Xiamen University, Xiamen 361005, P. R. China
| | - Chaoqun Zhan
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Electronic Science, Xiamen University, Xiamen 361005, P. R. China
| | - Yanqin Lin
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Electronic Science, Xiamen University, Xiamen 361005, P. R. China
| | - Zhong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Electronic Science, Xiamen University, Xiamen 361005, P. R. China
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Zeng Q, Chen J, Lin Y, Chen Z. Boosting resolution in NMR spectroscopy by chemical shift upscaling. Anal Chim Acta 2020; 1110:109-114. [PMID: 32278384 DOI: 10.1016/j.aca.2020.03.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/23/2020] [Accepted: 03/14/2020] [Indexed: 10/24/2022]
Abstract
Resolution is an essential challenge in NMR spectroscopy. Narrow chemical shift range and extensive signal splittings due to scalar couplings often give rise to spectral congestion and even overlap in NMR spectra. Magnetic field strength is directly responsible for spectral resolution as higher magnetic field strength offers better signal dispersion. However, the process of further increasing magnetic field strength of NMR instruments is slow and expensive. Methodology aimed at resolution issue has long been developing. Here, we present a chemical shift upscaling method, in which chemical shifts are upscaled by a given factor while scalar couplings are unchanged. As a result, signal dispersion and hence the resolution are improved. Therefore, it is possible to separate multiplets which originally overlap with each other and to extract their integrals for quantitative analysis. Improved signal dispersion and the preservation of scalar couplings also facilitate multiplet analysis and signal assignment. Chemical shift upscaling offers a method for enhancing resolution limited by magnetic field strength.
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Affiliation(s)
- Qing Zeng
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Jinyong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
| | - Zhong Chen
- Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Department of Electronic Science, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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12
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Koos MRM, Navarro‐Vázquez A, Anklin C, Gil RR. Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of
2
J
CH
in Addition to
3
J
CH
Coupling Constants. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Martin R. M. Koos
- Department of Chemistry Carnegie Mellon University Pittsburgh PA USA
| | | | | | - Roberto R. Gil
- Department of Chemistry Carnegie Mellon University Pittsburgh PA USA
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13
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Singh U, Bhattacharya S, Baishya B. Pure shift HMQC: Resolution and sensitivity enhancement by bilinear rotation decoupling in the indirect and direct dimensions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 311:106684. [PMID: 31931343 DOI: 10.1016/j.jmr.2020.106684] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/26/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
The heteronuclear multiple-quantum coherence in the indirect dimension of the two-dimensional HMQC experiment evolves under the passive 1H-1H J-couplings leading to multiplet structures in the F1 dimension. Besides, 1H-1H J-multiplets appear in the direct dimension as well. Thus, multiplets along both dimensions lower the resolution and sensitivity of this technique, when high resolution is required along both dimensions. An efficient broadband homodecoupling scheme along the F1 dimension of the HMQC experiment has not been realized to date. We have implemented broadband homonuclear decoupling using bilinear rotation decoupling (BIRD) by adding a 1H SQ evolution period followed by BIRD before the 1H-13C multiple-quantum evolution period in the HMQC. In the direct time domain, BIRD is implemented using a real-time or single-scan scheme, which further improves resolution and sensitivity of this technique. The resulting pure shift HMQC provides singlet peak per chemical site along F1 as well as F2 axes and, hence, better resolution and sensitivity than conventional HMQC spectrum for all peaks except diastereotopic methylene protons. Due to the incorporation of the BIRD, the indirect time domain becomes double in length compared to the conventional HMQC. However, slow relaxation of small molecules favors better sensitivity for ps-HMQC relative to conventional HMQC under all conditions. We also found that the sensitivity of ps-HMQC is only slightly less than ps-HSQC for small molecules.
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Affiliation(s)
- Upendra Singh
- Centre of Biomedical Research (Formerly Centre of Biomedical Magnetic Resonance), SGPGIMS Campus, Raebareli Road, Lucknow 226014, India; Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - Subrato Bhattacharya
- Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - Bikash Baishya
- Centre of Biomedical Research (Formerly Centre of Biomedical Magnetic Resonance), SGPGIMS Campus, Raebareli Road, Lucknow 226014, India.
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14
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Koos MRM, Navarro‐Vázquez A, Anklin C, Gil RR. Computer‐Assisted 3D Structure Elucidation (CASE‐3D): The Structural Value of
2
J
CH
in Addition to
3
J
CH
Coupling Constants. Angew Chem Int Ed Engl 2020; 59:3938-3941. [DOI: 10.1002/anie.201915103] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Indexed: 02/04/2023]
Affiliation(s)
- Martin R. M. Koos
- Department of Chemistry Carnegie Mellon University Pittsburgh PA USA
| | | | | | - Roberto R. Gil
- Department of Chemistry Carnegie Mellon University Pittsburgh PA USA
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Moreno A, Hansen KØ, Isaksson J. CSSF-CLIP-HSQMBC: measurement of heteronuclear coupling constants in severely crowded spectral regions. RSC Adv 2019; 9:36082-36087. [PMID: 35540578 PMCID: PMC9074913 DOI: 10.1039/c9ra04118d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/18/2019] [Indexed: 11/21/2022] Open
Abstract
A new pulse program development, a chemical shift selective filtration clean in-phase HSQMBC (CSSF-CLIP-HSQMBC), is presented for the user-friendly measurement of long-range heteronuclear coupling constants in severely crowded spectral regions. The introduction of the chemical shift selective filter makes the experiment extremely efficient at resolving overlapped multiplets and produces a clean selective CLIP-HSQMBC spectrum, in which the desired coupling constants can easily be measured as an extra proton-carbon splitting in f2. The pulse sequence is also provided as a real-time homonuclear decoupled version in which the heteronuclear coupling constant can be directly measured as the peak splitting in f2. The same principle is readily applicable to IPAP and AP versions of the same sequence as well as the optional TOCSY transfer, or in principle to any other selective heteronuclear experiment that relies on a clean 1H multiplet.
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Affiliation(s)
- Aitor Moreno
- Bruker BioSpin AG, Application Science Department CH-8117 Fällanden Switzerland
| | - Kine Østnes Hansen
- Marbio, UiT - The Arctic University of Norway Breivika NO-9037 Tromsø Norway
| | - Johan Isaksson
- Department of Chemistry, UiT - The Arctic University of Norway Breivika NO-9037 Tromsø Norway
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16
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Zhan C, Zeng Q, Chen J, Lin Y, Chen Z. PE-SERF: A sensitivity-improved experiment to measure J HH in crowded spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 308:106590. [PMID: 31513964 DOI: 10.1016/j.jmr.2019.106590] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/22/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
Aiming at facilitating the analysis of molecular structure, the gradient-encoded selective refocusing methods (G-SERF) and a great number of its variants for measuring proton-proton coupling constants have been proposed. However, the sensitivity is an issue in the 2D gradient-encoded experiments, because the signal intensity is determined by the slice thickness of the sample that depends on encoding gradient and the bandwidth of selective pulses which is limited by the smallest chemical shift difference of any two coupled protons. Here, we present a method dubbed PE-SERF (perfect echo selective refocusing) which can determine all JHH values involving a selected proton with improved sensitivity compared to original G-SERF experiment. The modules of perfect echo involving selective pulses and gradient-encoded selective refocusing are combined in the method, so that the unwanted J couplings arising from coupled spin pairs in the same sample slice would be nullified. In this way, instead of single proton, a pair of coupled protons is allowed to share a sample slice, and thus the slice thickness can be increased and the spectral sensitivity can be improved. The performance of the method is demonstrated by experiments on quinine and strychnine.
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Affiliation(s)
- Chaoqun Zhan
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Qing Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Jinyong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518057, China.
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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Kakita VMR, Rachineni K, Hosur RV. Ultraclean Pure Shift NMR Spectroscopy with Adiabatic Composite Refocusing Pulses: Application to Metabolite Samples. ChemistrySelect 2019. [DOI: 10.1002/slct.201902238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Veera Mohana Rao Kakita
- UM-DAE-Centre for Excellence in Basic SciencesUniversity of MumbaiKalina Campus, Santacruz 400 098 Mumbai India
| | - Kavitha Rachineni
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Powai 400076 Mumbai India
| | - Ramakrishna V Hosur
- UM-DAE-Centre for Excellence in Basic SciencesUniversity of MumbaiKalina Campus, Santacruz 400 098 Mumbai India
- Department of Biosciences and BioengineeringIndian Institute of Technology Bombay, Powai 400076 Mumbai India
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18
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Rao Kakita VM, Joshi MV, Hosur RV. G-SERF Editing in Two-Dimensional Pure-Shift Total Correlation Spectroscopy: Scalar Coupling Measurements for a Group of Spins in Organic Molecules. Chemphyschem 2019; 20:1559-1566. [PMID: 30997947 DOI: 10.1002/cphc.201900174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/13/2019] [Indexed: 11/10/2022]
Abstract
A novel G-SERF-PSYCHE-TOCSY (gradient encoded selective refocusing in pure shift yielded by chirp excitation version of total correlation spectroscopy) NMR pulse scheme has been proposed, which produces TOCSY chemical shift correlations, on one hand, and scalar coupling values for the spins scalarly coupled to irradiated resonances, by showing them as doublets along the indirect dimension, on the other. Therefore, recording such an experiment, for a group of spins with overlapping chemical shifts, in organic molecules can adequately provide scalar coupling information in a G-SERF manner along the indirect dimensions, and they can be assigned to particular spin pairs. Such COSY chemical shift correlations (which appear as doublets for the scalarly coupled spins) can be readily discriminated from the TOCSY peaks (which do not show such splitting) in the G-SERF-PSYCHE-TOCSY spectrum.
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Affiliation(s)
- Veera Mohana Rao Kakita
- UM-DAE-Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santacruz, Mumbai, 400 098, India
| | - Mamata V Joshi
- Department of Chemical Sciences, Tata Institute of Fundamental Research (TIFR), 1-Homi Bhabha Road, Colaba, Mumbai, 400 005, India
| | - Ramakrishna V Hosur
- UM-DAE-Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Santacruz, Mumbai, 400 098, India.,Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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19
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Zeng Q, Lin Y, Chen Z. Pushing resolution limits for extracting 1H- 1H scalar coupling constants by a resolution-enhanced selective refocusing method. J Chem Phys 2019; 150:184202. [PMID: 31091887 DOI: 10.1063/1.5089930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nuclear magnetic resonance (NMR) spectroscopy enables one to study molecular structure and dynamics in a noninvasive manner and has long served as a versatile and indispensable analytical tool in physics, chemistry, and biology. Scalar coupling, an essential feature in NMR spectroscopy, provides rich information regarding molecular structure and conformation. The measurement of scalar coupling constants, therefore, constitutes an important issue in NMR spectroscopy. Homonuclear 2D J-resolved spectroscopy is a powerful tool for multiplet analysis and coupling measurement. Recently, a number of phase-sensitive J-resolved methods and selective measuring methods have been developed to facilitate the extraction of coupling constants. However, resolution remains a crucial challenge when extracting small coupling constants or under inhomogeneous fields. In this paper, we present a resolution-enhanced selective refocusing (RESERF) method for the extraction of coupling constants. The effect of magnetic field inhomogeneity can be eliminated, resulting in very narrow linewidths. Therefore, samples with small coupling constants or under inhomogeneous fields can be well analyzed. The RESERF method may be of great value for structural and conformational studies in chemistry and biology.
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Affiliation(s)
- Qing Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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