The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Bikash Baishya - One of the best experts on this subject based on the ideXlab platform.
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pure shift hmqc resolution and sensitivity enhancement by Bilinear Rotation Decoupling in the indirect and direct dimensions
Journal of Magnetic Resonance, 2020Co-Authors: Upendra Singh, Subrato Bhattacharya, Bikash BaishyaAbstract: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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real time Bilinear Rotation Decoupling in absorptive mode j spectroscopy detecting low intensity metabolite peak close to high intensity metabolite peak with convenience
Journal of Magnetic Resonance, 2016Co-Authors: Ajay Verma, Bikash BaishyaAbstract:Abstract “Pure shift” NMR spectra display singlet peak per chemical site. Thus, high resolution is offered at the cost of valuable J -coupling information. In the present work, real-time BIRD (Bilinear Rotation Decoupling) is applied to the absorptive-mode 2D J -spectroscopy to provide pure shift spectrum in the direct dimension and J -coupling information in the indirect dimension. Quite often in metabolomics, proton NMR spectra from complex bio-fluids display tremendous signal overlap. Although conventional J -spectroscopy in principle overcomes this problem by separating the multiplet information from chemical shift information, however, only magnitude mode of the experiment is practical, sacrificing much of the potential high resolution that could be achieved. Few J -spectroscopy methods have been reported so far that produce high-resolution pure shift spectrum along with J -coupling information for crowded spectral regions. In the present work, high-quality J -resolved spectrum from important metabolomic mixture such as tissue extract from rat cortex is demonstrated. Many low-intensity metabolite peaks which are obscured by the broad dispersive tails from high-intensity metabolite peaks in regular magnitude mode J -spectrum can be clearly identified in real-time BIRD J -resolved spectrum. The general practice of removing such spectral overlap is tedious and time-consuming as it involves repeated sample preparation to change the pH of the tissue extract sample and subsequent spectra recording.
Ajay Verma - One of the best experts on this subject based on the ideXlab platform.
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real time Bilinear Rotation Decoupling in absorptive mode j spectroscopy detecting low intensity metabolite peak close to high intensity metabolite peak with convenience
Journal of Magnetic Resonance, 2016Co-Authors: Ajay Verma, Bikash BaishyaAbstract:Abstract “Pure shift” NMR spectra display singlet peak per chemical site. Thus, high resolution is offered at the cost of valuable J -coupling information. In the present work, real-time BIRD (Bilinear Rotation Decoupling) is applied to the absorptive-mode 2D J -spectroscopy to provide pure shift spectrum in the direct dimension and J -coupling information in the indirect dimension. Quite often in metabolomics, proton NMR spectra from complex bio-fluids display tremendous signal overlap. Although conventional J -spectroscopy in principle overcomes this problem by separating the multiplet information from chemical shift information, however, only magnitude mode of the experiment is practical, sacrificing much of the potential high resolution that could be achieved. Few J -spectroscopy methods have been reported so far that produce high-resolution pure shift spectrum along with J -coupling information for crowded spectral regions. In the present work, high-quality J -resolved spectrum from important metabolomic mixture such as tissue extract from rat cortex is demonstrated. Many low-intensity metabolite peaks which are obscured by the broad dispersive tails from high-intensity metabolite peaks in regular magnitude mode J -spectrum can be clearly identified in real-time BIRD J -resolved spectrum. The general practice of removing such spectral overlap is tedious and time-consuming as it involves repeated sample preparation to change the pH of the tissue extract sample and subsequent spectra recording.
Geoffrey Bodenhausen - One of the best experts on this subject based on the ideXlab platform.
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Attenuation of Cross-Peak Intensities in QUIET-BIRD-NOESY Experiments
Journal of Magnetic Resonance, 1999Co-Authors: Brian Cutting, Geoffrey BodenhausenAbstract:The buildup curves in QUIET-BIRD-NOESY expts., which are designed to isolate two-spin subsystems within macromols., are attenuated by transverse relaxation and evolution under homonuclear couplings during the Bilinear Rotation Decoupling (BIRD) pulse sandwich. If the signals of both source and target spins are attenuated equally (uniform damping), this is readily accounted for by normalizing the cross peaks with respect to the diagonal peaks. However, unequal attenuation of source and target spins (differential damping) affects the initial buildup slopes and hence leads to apparent cross-relaxation rates that are significantly distorted from their true values. A simple method for recognizing this situation and extg. accurate cross-relaxation rates is presented. (c) 1999 Academic Press. [on SciFinder (R)]
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A spectral window in protein NMR revealing cross-relaxation between amide protons
Journal of Magnetic Resonance, 1998Co-Authors: Pierre Mutzenhardt, Geoffrey BodenhausenAbstract:The principle of quenching undesirable indirect external trouble in nuclear Overhauser effect spectroscopy (QUIET-NOESY) relies on a doubly selective inversion of the longitudinal magnetization components of a source spin A and a target spin X to measure the cross-relaxation rate (Overhauser effect) between A and X without significant perturbation by spin diffusion. In 15N-enriched proteins, this can be achieved by using a Bilinear Rotation Decoupling (BIRD) sequence for the selective inversion of amide protons that have a scalar coupling to nitrogen-15. The procedure can be improved by using editing techniques to simplify the resulting NOESY spectra. [on SciFinder (R)]
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Measurement of Cross-Relaxation between Amide Protons in 15N-Enriched Proteins with Suppression of Spin Diffusion
Journal of the American Chemical Society, 1996Co-Authors: Sebastien J. F. Vincent, Catherine Zwahlen, Philip H. Bolton, Timothy M. Logan, Geoffrey BodenhausenAbstract:A variant of two-dimensional nuclear Overhauser effect spectroscopy (NOESY) is described which allows one to observe cross-relaxation pathways between protons that have heteronuclear scalar couplings to nitrogen-15 or carbon-13 nuclei. In 15N-enriched proteins, it is possible to focus attention on Overhauser effects between amide protons. All Overhauser effects between amide and other protons are eliminated by inserting a Bilinear Rotation Decoupling (BIRD) sequence in the middle of the relaxation interval. The mechanism of the suppression of cross relaxation is analogous to expts. involving selective inversion of the longitudinal magnetization of protons under investigation by quenching undesirable indirect external trouble in nuclear Overhauser effect spectroscopy (QUIET-NOESY). The new method is therefore called QUIET-BIRD-NOESY. [on SciFinder (R)]
Upendra Singh - One of the best experts on this subject based on the ideXlab platform.
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pure shift hmqc resolution and sensitivity enhancement by Bilinear Rotation Decoupling in the indirect and direct dimensions
Journal of Magnetic Resonance, 2020Co-Authors: Upendra Singh, Subrato Bhattacharya, Bikash BaishyaAbstract: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.
Subrato Bhattacharya - One of the best experts on this subject based on the ideXlab platform.
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pure shift hmqc resolution and sensitivity enhancement by Bilinear Rotation Decoupling in the indirect and direct dimensions
Journal of Magnetic Resonance, 2020Co-Authors: Upendra Singh, Subrato Bhattacharya, Bikash BaishyaAbstract: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.
