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Picazo-Frutos R, Sheberstov KF, Blanchard JW, Van Dyke E, Reh M, Sjoelander T, Pines A, Budker D, Barskiy DA. Zero-field J-spectroscopy of quadrupolar nuclei. Nat Commun 2024; 15:4487. [PMID: 38802356 DOI: 10.1038/s41467-024-48390-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/30/2024] [Indexed: 05/29/2024] Open
Abstract
Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) allows molecular structure elucidation via measurement of electron-mediated spin-spin J-couplings. This study examines zero-field J-spectra from molecules with quadrupolar nuclei, exemplified by solutions of various isotopologues of ammonium cations. The spectra reveal differences between various isotopologues upon extracting precise J-coupling values from pulse-acquire measurements. A primary isotope effect, △ J = γ 14 N / γ 15 N J 15 N H - J 14 N H ≈ - 58 mHz, is deduced by analysis of the proton-nitrogen J-coupling ratios. This study points toward further experiments with symmetric cations containing quadrupolar nuclei, promising applications in biomedicine, energy storage, and benchmarking quantum chemistry calculations.
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Affiliation(s)
- Román Picazo-Frutos
- Helmholtz-Institut Mainz, 55099, Mainz, Germany
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
| | - Kirill F Sheberstov
- Helmholtz-Institut Mainz, 55099, Mainz, Germany
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
- Department of Chemistry, École Normale Supérieure, PSL University, Paris, France
| | - John W Blanchard
- Helmholtz-Institut Mainz, 55099, Mainz, Germany
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
- Quantum Technology Center, University of Maryland, College Park, MD, USA
| | - Erik Van Dyke
- Helmholtz-Institut Mainz, 55099, Mainz, Germany
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
| | - Moritz Reh
- Department of Physics, University of California-Berkeley, Berkeley, CA, 94720, USA
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120, Heidelberg, Germany
| | - Tobias Sjoelander
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel, CH-4056, Switzerland
- Department of Chemistry, University of California, Berkeley, CA, 94720-3220, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720-3220, USA
| | - Alexander Pines
- Department of Chemistry, University of California, Berkeley, CA, 94720-3220, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720-3220, USA
| | - Dmitry Budker
- Helmholtz-Institut Mainz, 55099, Mainz, Germany
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
- Department of Physics, University of California-Berkeley, Berkeley, CA, 94720, USA
| | - Danila A Barskiy
- Helmholtz-Institut Mainz, 55099, Mainz, Germany.
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128, Mainz, Germany.
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany.
- Department of Chemistry, University of California, Berkeley, CA, 94720-3220, USA.
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Lysak DH, Wolff WW, Soong R, Bermel W, Kupče ER, Jenne A, Biswas RG, Lane D, Gasmi-Seabrook G, Simpson A. Application of 15N-Edited 1H- 13C Correlation NMR Spectroscopy─Toward Fragment-Based Metabolite Identification and Screening via HCN Constructs. Anal Chem 2023; 95:11926-11933. [PMID: 37535003 DOI: 10.1021/acs.analchem.3c01362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Many key building blocks of life contain nitrogen moieties. Despite the prevalence of nitrogen-containing metabolites in nature, 15N nuclei are seldom used in NMR-based metabolite assignment due to their low natural abundance and lack of comprehensive chemical shift databases. However, with advancements in isotope labeling strategies, 13C and 15N enriched metabolites are becoming more common in metabolomic studies. Simple multidimensional nuclear magnetic resonance (NMR) experiments that correlate 1H and 15N via single bond 1JNH or multiple bond 2-3JNH couplings using heteronuclear single quantum coherence (HSQC) or heteronuclear multiple bond coherence are well established and routinely applied for structure elucidation. However, a 1H-15N correlation spectrum of a metabolite mixture can be difficult to deconvolute, due to the lack of a 15N specific database. In order to bridge this gap, we present here a broadband 15N-edited 1H-13C HSQC NMR experiment that targets metabolites containing 15N moieties. Through this approach, nitrogen-containing metabolites, such as amino acids, nucleotide bases, and nucleosides, are identified based on their 13C, 1H, and 15N chemical shift information. This approach was tested and validated using a [15N, 13C] enriched Daphnia magna (water flea) metabolite extract, where the number of clearly resolved 15N-containing peaks increased from only 11 in a standard HSQC to 51 in the 15N-edited HSQC, and the number of obscured peaks decreased from 59 to just 7. The approach complements the current repertoire of NMR techniques for mixture deconvolution and holds considerable potential for targeted metabolite NMR in 15N, 13C enriched systems.
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Affiliation(s)
- Daniel H Lysak
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - William W Wolff
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Ronald Soong
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, Ettlingen 76275, Germany
| | | | - Amy Jenne
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Rajshree Ghosh Biswas
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Daniel Lane
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | | | - Andre Simpson
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
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Lin Q, Meng C, Liu J, Liu F, Zhou Q, Liu J, Peng C, Xiong L. An Optimized Two-Dimensional Quantitative Nuclear Magnetic Resonance Strategy for the Rapid Quantitation of Diester-Type C 19-Diterpenoid Alkaloids from Aconitum carmichaelii. Anal Chem 2023. [PMID: 37209123 DOI: 10.1021/acs.analchem.2c05109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
With the development of nuclear magnetic resonance (NMR) spectrometers and probes, two-dimensional quantitative nuclear magnetic resonance (2D qNMR) technology with a high signal resolution and great application potential has become increasingly accessible for the quantitation of complex mixtures. However, the requirement that the relaxation recovery time be equal to at least five times T1 (longitudinal relaxation time) makes it difficult for 2D qNMR to simultaneously achieve high quantitative accuracy and high data acquisition efficiency. By comprehensively using relaxation optimization and nonuniform sampling, we successfully established an optimized 2D qNMR strategy for HSQC experiments at the half-hour level and then accurately quantified the diester-type C19-diterpenoid alkaloids in Aconitum carmichaelii. The optimized strategy had the advantages of high efficiency, high accuracy, good reproducibility, and low cost and thus could serve as a reference to optimize 2D qNMR experiments for quantitative analysis of natural products, metabolites, and other complex mixtures.
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Affiliation(s)
- Qiao Lin
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Chunwang Meng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Jie Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Fei Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Qinmei Zhou
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Juan Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Liang Xiong
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
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Martinho RP, Frydman L. Harnessing Water to Enhance Quadrupolar NMR Spectroscopy and Imaging. Chemistry 2022; 28:e202201490. [PMID: 36062375 PMCID: PMC9828088 DOI: 10.1002/chem.202201490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Indexed: 01/12/2023]
Abstract
17 O and 14 N are attractive targets for in vivo NMR spectroscopy and imaging, but low gyromagnetic ratios γ and fast spin relaxation complicate observations. This work explores indirect ways of detecting some of these sites with the help of proton-detected double resonance techniques. As standard coherence transfer methods are of limited use for such indirect detection, alternative routes for probing the quadrupolar spectra on 1 H were tested. These centered on modulating the broadening effects imparted onto protons adjacent to the low-γ species through J couplings through either continuous wave or spin-echo double-resonance decoupling/recoupling sequences. As in all cases, the changes imparted by these double-resonance strategies were small due to the fast relaxation undergone by the quadrupoles, the sensitivity of these approaches was amplified by transferring their effects onto the abundant water 1 H signal. These amplifications were mediated by the spontaneous exchanges that the labile 1 Hs bound to 17 O or 14 N undergo with the water protons. In experiments designed on the basis of double-resonance spin echoes, these enhancements were imparted by looping the transverse encodings together with multiple longitudinal storage periods, leading to decoupling-recoupling with exchange (D-REX) sequences. In experiments designed on the basis of continuous on/off quadrupolar decoupling, these solvent exchanges were incorporated into chemical-exchange saturation transfer schemes, leading to decoupling-recoupling with saturation transfer (D-REST) sequences. Both of these variants harnessed sizable proportions of the easily detectable water signals, in order to characterize the NMR spectra and/or to image with atomic-site specificity the 17 O and 14 N species.
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Affiliation(s)
- Ricardo P. Martinho
- Department of Chemical and Biological PhysicsWeizmann Institute of Science7610001RehovotIsrael
| | - Lucio Frydman
- Department of Chemical and Biological PhysicsWeizmann Institute of Science7610001RehovotIsrael
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5
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Kil YS, Han AR, Hong MJ, Kim JB, Park PH, Choi H, Nam JW. 1H NMR-Based Chemometrics to Gain Insights Into the Bran of Radiation-Induced Colored Wheat Mutant. Front Nutr 2022; 8:806744. [PMID: 35059428 PMCID: PMC8764193 DOI: 10.3389/fnut.2021.806744] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/06/2021] [Indexed: 11/22/2022] Open
Abstract
Recently, wheat has attracted attention as a functional food, rather than a simple dietary energy source. Accordingly, whole-grain intake increases with an understanding of bioactive phytochemicals in bran. The development of colored wheat has drawn more attention to the value of bran owing to its nutritional quality, as well as the antioxidant properties of the colorant. The present 1H NMR-based chemometric study evaluated the compositional improvement of radiation-induced mutants in purple wheat by focusing on the predominant metabolites with high polarity. A total of 33 metabolites, including three choline derivatives, three sugar alcohols, four sugars, 13 amino acids, eight organic acids, and two nucleosides, were identified throughout the 1H NMR spectra, and quantification data were obtained for the identified metabolites via peak shape-based quantification. Principal component and hierarchical cluster analyses were conducted for performing multivariate analyses. The colored original wheat was found to exhibit improvements compared to yellow wheat in terms of the contents of primary metabolites, thus highlighting the importance of conducting investigations of polar metabolites. The chemometrics studies further revealed mutant lines with a compositional enhancement for metabolites, including lysine, proline, acetate, and glycerol.
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Affiliation(s)
- Yun-Seo Kil
- College of Pharmacy, Yeungnam University, Gyeongsan-si, South Korea
| | - Ah-Reum Han
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, South Korea
| | - Min-Jeong Hong
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, South Korea
| | - Jin-Baek Kim
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, South Korea
| | - Pil-Hoon Park
- College of Pharmacy, Yeungnam University, Gyeongsan-si, South Korea.,Research Institute of Cell Culture, Yeungnam University, Gyeongsan-si, South Korea
| | - Hyukjae Choi
- College of Pharmacy, Yeungnam University, Gyeongsan-si, South Korea.,Research Institute of Cell Culture, Yeungnam University, Gyeongsan-si, South Korea
| | - Joo-Won Nam
- College of Pharmacy, Yeungnam University, Gyeongsan-si, South Korea
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6
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Ruiz-Muelle AB, Moreno PG, Fernández I. Quantitative quadrupolar NMR (qQNMR) using nitrogen-14 for the determination of choline in complex matrixes. Talanta 2021; 230:122344. [PMID: 33934793 DOI: 10.1016/j.talanta.2021.122344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/15/2021] [Accepted: 03/18/2021] [Indexed: 01/17/2023]
Abstract
NMR offers the unique potential to selectively excite the chosen nuclei avoiding in an extraordinary way the matrix effect. Quantitative Nitrogen-14 NMR (14N qNMR) spectroscopy has been introduced for the first time as a robust and validated method to determine choline in a variety of matrixes including quinoa grains, instant coffee and food supplements. A study about the ion pairing of choline bitartrate in aqueous solution by means of diffusion PGSE, NOESY and HOESY NMR have been also provided. Validation of the method within eight concentrations levels (from 1.58 to 79.0 mM) afforded a limit of detection of 400 μg/mL (1.58 mM), a quantification limit of 1000 μg/mL (3.95 mM), excellent linearity (R2 higher than 0.999), intra-/inter-day precisions lower than 1.24% (CV), recoveries of 93.5%-102.5%, and complete absence of matrix effect. The fast and reliable quantification of choline together with the accuracy and simplicity of this new approach make it useful in the development of analytical procedures that could dramatically affect traditional analysis.
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Affiliation(s)
- Ana Belén Ruiz-Muelle
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain
| | - Paula García Moreno
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain
| | - Ignacio Fernández
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain.
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7
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A Crosstalk- and Interferent-Free Dual Electrode Amperometric Biosensor for the Simultaneous Determination of Choline and Phosphocholine. SENSORS 2021; 21:s21103545. [PMID: 34069690 PMCID: PMC8160789 DOI: 10.3390/s21103545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 05/14/2021] [Indexed: 11/22/2022]
Abstract
Choline (Ch) and phosphocholine (PCh) levels in tissues are associated to tissue growth and so to carcinogenesis. Till now, only highly sophisticated and expensive techniques like those based on NMR spectroscopy or GC/LC- high resolution mass spectrometry permitted Ch and PCh analysis but very few of them were capable of a simultaneous determination of these analytes. Thus, a never reported before amperometric biosensor for PCh analysis based on choline oxidase and alkaline phosphatase co-immobilized onto a Pt electrode by co-crosslinking has been developed. Coupling the developed biosensor with a parallel sensor but specific to Ch, a crosstalk-free dual electrode biosensor was also developed, permitting the simultaneous determination of Ch and PCh in flow injection analysis. This novel sensing device performed remarkably in terms of sensitivity, linear range, and limit of detection so to exceed in most cases the more complex analytical instrumentations. Further, electrode modification by overoxidized polypyrrole permitted the development of a fouling- and interferent-free dual electrode biosensor which appeared promising for the simultaneous determination of Ch and PCh in a real sample.
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Sun P, Wang Q, Yuan B, Zhu Q, Jiang B, Li C, Lan W, Cao C, Zhang X, Liu M. Monitoring alkaline transitions of yeast iso-1 cytochrome c at natural isotopic abundance using trimethyllysine as a native NMR probe. Chem Commun (Camb) 2018; 54:12630-12633. [PMID: 30351312 DOI: 10.1039/c8cc07605g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Spectral overlap makes it difficult to use NMR for mapping the conformational profile of heterogeneous conformational ensembles of macromolecules. Here, we apply a 1H-14N HSQC experiment to monitor the alkaline conformational transitions of yeast iso-1 cytochrome c (ycyt c) at natural isotopic abundance. Trimethylated Lys72 of ycyt c is selectively detected by a 1H-14N HSQC experiment, and used as a probe to trace conformational transitions of ycyt c under alkaline conditions. It was found that at least four different conformers of ycyt c coexisted under alkaline conditions. Besides the native structure, Lys73 or Lys79 coordinated conformers and a partially unfolded state with exposed heme were observed. These results indicate that the method is powerful at simplifying spectra of a trimethylated protein, which makes it possible to study complex conformational transitions of naturally extracted or chemically modified trimethylated protein at natural isotopic abundance.
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Affiliation(s)
- Peng Sun
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan National Center for Magnetic Resonance, CAS Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.
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9
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Pathway of glycine betaine biosynthesis in Aspergillus fumigatus. EUKARYOTIC CELL 2013; 12:853-63. [PMID: 23563483 DOI: 10.1128/ec.00348-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The choline oxidase (CHOA) and betaine aldehyde dehydrogenase (BADH) genes identified in Aspergillus fumigatus are present as a cluster specific for fungal genomes. Biochemical and molecular analyses of this cluster showed that it has very specific biochemical and functional features that make it unique and different from its plant and bacterial homologs. A. fumigatus ChoAp catalyzed the oxidation of choline to glycine betaine with betaine aldehyde as an intermediate and reduced molecular oxygen to hydrogen peroxide using FAD as a cofactor. A. fumigatus Badhp oxidized betaine aldehyde to glycine betaine with reduction of NAD(+) to NADH. Analysis of the AfchoAΔ::HPH and AfbadAΔ::HPH single mutants and the AfchoAΔAfbadAΔ::HPH double mutant showed that AfChoAp is essential for the use of choline as the sole nitrogen, carbon, or carbon and nitrogen source during the germination process. AfChoAp and AfBadAp were localized in the cytosol of germinating conidia and mycelia but were absent from resting conidia. Characterization of the mutant phenotypes showed that glycine betaine in A. fumigatus functions exclusively as a metabolic intermediate in the catabolism of choline and not as a stress protectant. This study in A. fumigatus is the first molecular, cellular, and biochemical characterization of the glycine betaine biosynthetic pathway in the fungal kingdom.
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Mao XA, Jiang B, Jiang L, Liu M. (1)H- (31)P soft-HSQC pulse sequence specifically for detecting phosphomono- and diesters in biological samples. Mol Imaging Biol 2012; 15:245-9. [PMID: 23229351 DOI: 10.1007/s11307-012-0607-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE Phosphomono- and diesters (PME and PDE) are important metabolites that are potential biomarkers for a number of cancers. We designed a new NMR pulse sequence, i.e., (1)H-(31)P soft-heteronuclear single quantum correlation (HSQC), specifically for noninvasively detecting PME and PDE in biological samples. PROCEDURE The nonselective (1)H refocusing π pulses in the conventional heteronuclear single quantum correlation pulse sequence are replaced by selective π pulses. When the selective pulses are offset on the CH2O resonances, the homonuclear couplings between the NCH2 and CH2O protons are effectively removed, and the spectrum of PME and PDE is significantly enhanced. RESULTS The sensitivity of this pulse sequence has been demonstrated with milk and mouse brain samples. A soft-HSQC spectrum, where only PME and PDE signals appear, can be recorded from these biological samples in minutes with remarkably high signal-to-noise ratio. CONCLUSION This pulse sequence provides a new and quick method for in vivo studies of phosphorus metabolite in the human brain and other tissues for medical purposes.
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Affiliation(s)
- Xi-an Mao
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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11
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Cao C, Mao J, Li F, Yang M, He H, Jiang L, Liu M. Understanding the interaction between valsartan and detergents by NMR techniques and molecular dynamics simulation. J Phys Chem B 2012; 116:7470-8. [PMID: 22708715 DOI: 10.1021/jp304304v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Valsartan (VST) is one of the Angiotensin II receptor antagonists, which is widely used in clinical hypertension treatment. It is believed that VST incorporates into biological membranes before it binds to AT(1) receptor. Herein the interactions between VST and detergents, mimicking the membrane environment, were investigated by using nuclear magnetic resonance (NMR) techniques and molecular dynamics (MD) simulation. We observed that VST has two conformers (trans and cis) exchanging slowly in DPC (dodecyl-phosphocholine) micelles, a widely used detergent. The changes of chemical shifts, relaxation rates, and self-diffusion coefficients of VST protons indicate that both conformers have strong interactions with DPC. NOE cross peaks and MD simulation reveal that DPC interacts with VST not only through the hydrophobic lipid chain, but also the hydrophilic headgroup, locating VST at the charged headgroup and upper part of the micelles. Our results are in good agreement with the Raman spectroscopic studies of VST in the DPPC (dipalmitoyl-phosphatidylcholine) bilayers by Potamitis et al. (Biochim. Biophys. Acta. 2011). The concentration ratio of trans over cis conformers is 0.94, showing that two conformers have the same affinities with the detergent, which is significantly smaller than our previous results obtained in SDS (sodium dodecyl sulfate) micelles. MD simulation suggested that the cis conformer has slightly lower binding free energy than the trans conformer when interacting with DPC. The conformational change of VST was further investigated in two detergents, CTAB (hexadecyltrimethylammonium bromide) and Tween-20 (polysorbate 20). Ratios of conformer A and B in the presence of detergents are in the order of DPC, CTAB < Tween-20 < SDS, which is correlated with the charge characters of their head groups. NMR investigations and MD simulations indicate that the electrostatic interaction plays an essential role in the binding process of VST with detergents, and the hydrophobic interaction influences the packing of the drug in the micelles. These results may be of help in understanding delivery processes of sartan drugs in cell membranes.
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Affiliation(s)
- Chenyu Cao
- School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
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Mao XA, Li N, Mao J, Li Q, Xiao N, Jiang B, Jiang L, Wang XX, Liu M. Fast detection of choline-containing metabolites in liver using 2D ¹H-¹⁴N three-bond correlation (HN3BC) spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 214:352-359. [PMID: 22204824 DOI: 10.1016/j.jmr.2011.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 11/28/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Abstract
Detection and quantification of total choline-containing metabolites (CCMs) in tissues by magnetic resonance spectroscopy (MRS) has received considerable attention as a biomarker of cancer. Tissue CCMs are mainly choline (Cho), phosphocholine (PCho), and glycerophosphocholine (GPCho). Because the methyl (1)H resonances of tissue CCMs exhibit small chemical shift differences and overlap significantly in 1D (1)H MRS, quantification of individual components is precluded. Development of a MRS method capably of resolving individual components of tissue CCMs would be a significant advance. Herein, a modification of the 2D (1)H-(14)N HSQC technique is targeted on the two methylene (1)H in the CH(2)O group ((3)J(1H14N)=2.7 Hz) and applied to ex vivo mouse and human liver samples at physiological temperature (37°C). Specifically, the (1)H-(14)N HSQC technique is modified into a 2D (1)H-(14)N three-bond correlation (HN3BC) experiment, which selectively detects the (1)H of CH(2)O coupled to (14)N in CCMs. Separate signals from Cho, PCho, and GPCho components are resolved with high detection sensitivity. A 2D HN3BC spectrum can be recorded from mouse liver in only 1.5 min and from human carcinoma liver tissue in less than 3 min with effective sample volume of 0.2 ml at 14.1T.
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Affiliation(s)
- Xi-An Mao
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
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13
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Mao J, Jiang L, Jiang B, Liu M, Mao XA. A selective NMR method for detecting choline containing compounds in liver tissue: the 1H-14N HSQC experiment. J Am Chem Soc 2010; 132:17349-51. [PMID: 21090567 DOI: 10.1021/ja107745g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The feasibility of a (1)H-(14)N HSQC experiment on tissues is demonstrated with a mouse liver based on the J couplings between the protons and the quadrupolar nucleus (14)N in choline. Free choline, phosphocholine, and glycerolphosphocholine (1)H-(14)N HSQC signals were selectively observed with all unwanted signals cleanly suppressed. The CH2O signals were well resolved in the two-dimensional spectrum, which can be used for quantitative analyses.
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Affiliation(s)
- Jiezhen Mao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, China
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