The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Rafael Bruschweiler - One of the best experts on this subject based on the ideXlab platform.
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absolute minimal sampling of Homonuclear 2D NMR tocsy spectra for high throughput applications of complex mixtures
Angewandte Chemie, 2017Co-Authors: Alexandar L Hansen, Cheng Wang, Rafael BruschweilerAbstract:Modern applications of 2D NMR spectroscopy to diagnostic screening, metabolomics, quality control, and other high-throughput applications are often limited by the time-consuming sampling requirements along the indirect time domain t1 . 2D total correlation spectroscopy (TOCSY) provides unique spin connectivity information for the analysis of a large number of compounds in complex mixtures, but standard methods typically require >100 t1 increments for an accurate spectral reconstruction, rendering these experiments ineffective for high-throughput applications. For a complex metabolite mixture it is demonstrated that absolute minimal sampling (AMS), based on direct fitting of resonance frequencies and amplitudes in the time domain, yields an accurate spectral reconstruction of TOCSY spectra using as few as 16 t1 points. This permits the rapid collection of Homonuclear 2D NMR experiments at high resolution with measurement times that previously were only the realm of 1D experiments.
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high resolution Homonuclear 2D NMR of carbon 13 enriched metabolites and their mixtures
Journal of Magnetic Resonance, 2012Co-Authors: Fengli Zhang, Lei Bruschweilerli, Rafael BruschweilerAbstract:Abstract High-resolution 2D 13 C– 13 C NMR correlation spectra of uniformly 13 C-labeled molecules in solution are obtained by Homonuclear 13 C-decoupling along both dimensions by the application of indirect covariance NMR to constant-time NMR spectra. The spectra are optimally suited for chemical structure elucidation and molecular identification of the components of complex mixtures, such as ones from uniformly 13 C-labeled cell cultures.
Wolfram Gronwald - One of the best experts on this subject based on the ideXlab platform.
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systematic evaluation of non uniform sampling parameters in the targeted analysis of urine metabolites by 1h 1h 2D NMR spectroscopy
Scientific Reports, 2018Co-Authors: Trixi Von Schlippenbach, Peter J Oefner, Wolfram GronwaldAbstract:Non-uniform sampling (NUS) allows the accelerated acquisition of multidimensional NMR spectra. The aim of this contribution was the systematic evaluation of the impact of various quantitative NUS parameters on the accuracy and precision of 2D NMR measurements of urinary metabolites. Urine aliquots spiked with varying concentrations (15.6–500.0 µM) of tryptophan, tyrosine, glutamine, glutamic acid, lactic acid, and threonine, which can only be resolved fully by 2D NMR, were used to assess the influence of the sampling scheme, reconstruction algorithm, amount of omitted data points, and seed value on the quantitative performance of NUS in 1H,1H-TOCSY and 1H,1H-COSY45 NMR spectroscopy. Sinusoidal Poisson-gap sampling and a compressed sensing approach employing the iterative re-weighted least squares method for spectral reconstruction allowed a 50% reduction in measurement time while maintaining sufficient quantitative accuracy and precision for both types of Homonuclear 2D NMR spectroscopy. Together with other advances in instrument design, such as state-of-the-art cryogenic probes, use of 2D NMR spectroscopy in large biomedical cohort studies seems feasible.
Trixi Von Schlippenbach - One of the best experts on this subject based on the ideXlab platform.
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systematic evaluation of non uniform sampling parameters in the targeted analysis of urine metabolites by 1h 1h 2D NMR spectroscopy
Scientific Reports, 2018Co-Authors: Trixi Von Schlippenbach, Peter J Oefner, Wolfram GronwaldAbstract:Non-uniform sampling (NUS) allows the accelerated acquisition of multidimensional NMR spectra. The aim of this contribution was the systematic evaluation of the impact of various quantitative NUS parameters on the accuracy and precision of 2D NMR measurements of urinary metabolites. Urine aliquots spiked with varying concentrations (15.6–500.0 µM) of tryptophan, tyrosine, glutamine, glutamic acid, lactic acid, and threonine, which can only be resolved fully by 2D NMR, were used to assess the influence of the sampling scheme, reconstruction algorithm, amount of omitted data points, and seed value on the quantitative performance of NUS in 1H,1H-TOCSY and 1H,1H-COSY45 NMR spectroscopy. Sinusoidal Poisson-gap sampling and a compressed sensing approach employing the iterative re-weighted least squares method for spectral reconstruction allowed a 50% reduction in measurement time while maintaining sufficient quantitative accuracy and precision for both types of Homonuclear 2D NMR spectroscopy. Together with other advances in instrument design, such as state-of-the-art cryogenic probes, use of 2D NMR spectroscopy in large biomedical cohort studies seems feasible.
Jinfa Ying - One of the best experts on this subject based on the ideXlab platform.
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Homonuclear decoupling for enhancing resolution and sensitivity in noe and rdc measurements of peptides and proteins
Journal of Magnetic Resonance, 2014Co-Authors: Jinfa Ying, Julien Roche, Ad BaxAbstract:Abstract Application of band-selective Homonuclear (BASH) 1 H decoupling pulses during acquisition of the 1 H free induction decay is shown to be an efficient procedure for removal of scalar and residual dipolar couplings between amide and aliphatic protons. BASH decoupling can be applied in both dimensions of a Homonuclear 2D NMR experiment and is particularly useful for enhancing spectral resolution in the H N –H α region of NOESY spectra of peptides and proteins, which contain important information on the backbone torsion angles. The method then also prevents generation of zero quantum and H z N – H z α terms, thereby facilitating analysis of intraresidue interactions. Application to the NOESY spectrum of a hexapeptide fragment of the intrinsically disordered protein α-synuclein highlights the considerable diffusion anisotropy present in linear peptides. Removal of residual dipolar couplings between H N and aliphatic protons in weakly aligned proteins increases resolution in the 1 H– 15 N HSQC region of the spectrum and allows measurement of RDCs in samples that are relatively strongly aligned. The approach is demonstrated for measurement of RDCs in protonated 15 N/ 13 C-enriched ubiquitin, aligned in Pf1, yielding improved fitting to the ubiquitin structure.
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NMR Solution Structure of the Glucagon Antagonist [desHis1, desPhe6, Glu9]Glucagon Amide in the Presence of Perdeuterated Dodecylphosphocholine Micelles†,‡
2002Co-Authors: Jinfa Ying, Jung-mo Ahn, Neil E. Jacobsen, Michael F. Brown, Victor J. HrubyAbstract:ABSTRACT: Glucagon, a 29-residue peptide hormone, plays an important role in glucose homeostasis and in diabetes mellitus. Several glucagon antagonists and agonists have been developed, but limited structural information is available to clarify the basis of their biological activity. The solution structure of the potent glucagon antagonist, [desHis1, desPhe6, Glu9]glucagon amide, was determined by Homonuclear 2D NMR spectroscopy at pH 6.0 and 37 °C in perdeuterated dodecylphosphocholine micelles. The overall backbone root-mean-square deviation (rmsd) for the structured portion (residues 7-29, glucagon numbering) of the micelle-bound 27-residue peptide is 1.36 Å for the 15 lowest-energy structures, after restrained molecular dynamics simulation. The structure consists of four regions (segment backbone rmsd in Å): an unstructured N-terminal segment between residues 2 and 5 (1.68), an irregular helix between residues 7 and 14 (0.79), a hinge region between residues 15 and 18 (0.54), and a well-defined R-helix between residues 19 and 29 (0.33). The two helices form an L-shaped structure with an angle of about 90 ° between the helix axes. There is an extended hydrophobic cluster, which runs along the inner surface of the L-structure and incorporates the side chains of the hydrophobic residues of each of the amphipathic helices. The outer surface contains the hydrophilic side chains, with two salt bridges (D15-R18 and R17-D21) implied from close approach of the charged groups. This result is the first clear indication of an overall tertiary fold fo
Fengli Zhang - One of the best experts on this subject based on the ideXlab platform.
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high resolution Homonuclear 2D NMR of carbon 13 enriched metabolites and their mixtures
Journal of Magnetic Resonance, 2012Co-Authors: Fengli Zhang, Lei Bruschweilerli, Rafael BruschweilerAbstract:Abstract High-resolution 2D 13 C– 13 C NMR correlation spectra of uniformly 13 C-labeled molecules in solution are obtained by Homonuclear 13 C-decoupling along both dimensions by the application of indirect covariance NMR to constant-time NMR spectra. The spectra are optimally suited for chemical structure elucidation and molecular identification of the components of complex mixtures, such as ones from uniformly 13 C-labeled cell cultures.