The application of two-dimensional J-resolved nuclear magnetic resonance spectroscopy to determine the structure of two bile metabolites isolated from rats injected interperitoneally with bromobenzene is described. The structures of the two molecules are obtained unambiguously from the proton-proton spin coupling constants. This paper discusses the fundamentals of the technique and demonstrates the resolution of small long-range coupling constants.
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http://dx.doi.org/10.1289/ehp.8561139 | DOI Listing |
Bioinformatics
January 2025
Section of Bioinformatics, Division of Systems Medicine, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, W12 0NN, United Kingdom.
Unlabelled: Metabolomics extensively utilizes Nuclear Magnetic Resonance (NMR) spectroscopy due to its excellent reproducibility and high throughput. Both one-dimensional (1D) and two-dimensional (2D) NMR spectra provide crucial information for metabolite annotation and quantification, yet present complex overlapping patterns which may require sophisticated machine learning algorithms to decipher. Unfortunately, the limited availability of labeled spectra can hamper application of machine learning, especially deep learning algorithms which require large amounts of labelled data.
View Article and Find Full Text PDFNat Commun
December 2024
Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
While H-H J-couplings are the cornerstone of all spectral assignment methods in solution-state NMR, they are yet to be observed in solids. Here we observe H-H J-couplings in plastic crystals of (1S)-(-)-camphor in solid-state NMR at magic angle spinning (MAS) rates of 100 kHz and above. This is enabled in this special case because the intrinsic coherence lifetimes at fast MAS rates become longer than the inverse of the H-H J couplings.
View Article and Find Full Text PDFMagn Reson Chem
December 2024
Centre of Bio-Medical Research (CBMR), Sanjay Gandhi Post Institute of Medical Sciences Campus, Lucknow, Uttar Pradesh, India.
Catharanthus roseus, also known as Madagascar periwinkle, is a perennial plant renowned for its extensive pharmacological properties. It produces vital chemotherapeutic compounds, including vinblastine and vincristine, and exhibits anti-inflammatory, antidiabetic, and antioxidant activities. In this study, we utilized a range of two-dimensional (2D) nuclear magnetic resonance (NMR) techniques, such as H-H correlation spectroscopy (COSY), H-H J-resolved NMR, and H-C heteronuclear single quantum coherence (HSQC) sensitivity-enhanced NMR spectroscopy, to identify key metabolites in C.
View Article and Find Full Text PDFJ Phys Chem A
November 2024
Quantum Theory Project, Departments of Chemistry and Physics, University of Florida, Gainesville, Florida 32611, United States.
The thermal unimolecular decay of ethoxy is important in high-temperature combustion environments where the ethoxy radical is a key reactive intermediate. Two dissociation pathways of ethoxy, including the β-C-C scission to yield CH + CHO and the H-elimination to make H + CHCHO, were characterized using a high-level coupled-cluster-based composite quantum chemical method (mHEAT-345(Q)). The former route is found to be dominant while the latter is insignificant, in agreement with previous experimental and theoretical studies.
View Article and Find Full Text PDFAnal Chem
July 2024
Section of Bioinformatics, Division of Systems Medicine, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, U.K.
J-Resolved (J-Res) nuclear magnetic resonance (NMR) spectroscopy is pivotal in NMR-based metabolomics, but practitioners face a choice between time-consuming high-resolution (HR) experiments or shorter low-resolution (LR) experiments which exhibit significant peak overlap. Deep learning neural networks have been successfully used in many fields to enhance quality of natural images, especially with regard to resolution, and therefore offer the prospect of improving two-dimensional (2D) NMR data. Here, we introduce the J-RESRGAN, an adapted and modified generative adversarial network (GAN) for image super-resolution (SR), which we trained specifically for metabolomic J-Res spectra to enhance peak resolution.
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