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Gustafsson J, Roshanzamir F, Hagnestål A, Patel SM, Daudu OI, Becker DF, Robinson JL, Nielsen J. Metabolic collaboration between cells in the tumor microenvironment has a negligible effect on tumor growth. Innovation (N Y) 2024; 5:100583. [PMID: 38445018 PMCID: PMC10912649 DOI: 10.1016/j.xinn.2024.100583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 01/24/2024] [Indexed: 03/07/2024] Open
Abstract
The tumor microenvironment is composed of a complex mixture of different cell types interacting under conditions of nutrient deprivation, but the metabolism therein is not fully understood due to difficulties in measuring metabolic fluxes and exchange of metabolites between different cell types in vivo. Genome-scale metabolic modeling enables estimation of such exchange fluxes as well as an opportunity to gain insight into the metabolic behavior of individual cell types. Here, we estimated the availability of nutrients and oxygen within the tumor microenvironment using concentration measurements from blood together with a metabolite diffusion model. In addition, we developed an approach to efficiently apply enzyme usage constraints in a comprehensive metabolic model of human cells. The combined modeling reproduced severe hypoxic conditions and the Warburg effect, and we found that limitations in enzymatic capacity contribute to cancer cells' preferential use of glutamine as a substrate to the citric acid cycle. Furthermore, we investigated the common hypothesis that some stromal cells are exploited by cancer cells to produce metabolites useful for the cancer cells. We identified over 200 potential metabolites that could support collaboration between cancer cells and cancer-associated fibroblasts, but when limiting to metabolites previously identified to participate in such collaboration, no growth advantage was observed. Our work highlights the importance of enzymatic capacity limitations for cell behaviors and exemplifies the utility of enzyme-constrained models for accurate prediction of metabolism in cells and tumor microenvironments.
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Affiliation(s)
- Johan Gustafsson
- Department of Life Sciences, Chalmers University of Technology, SE- 412 96 Gothenburg, Sweden
| | - Fariba Roshanzamir
- Department of Life Sciences, Chalmers University of Technology, SE- 412 96 Gothenburg, Sweden
| | | | - Sagar M. Patel
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Oseeyi I. Daudu
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Donald F. Becker
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Jonathan L. Robinson
- Department of Life Sciences, Chalmers University of Technology, SE- 412 96 Gothenburg, Sweden
- BioInnovation Institute, DK2200 Copenhagen, Denmark
| | - Jens Nielsen
- Department of Life Sciences, Chalmers University of Technology, SE- 412 96 Gothenburg, Sweden
- BioInnovation Institute, DK2200 Copenhagen, Denmark
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2
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A Simple Elimination of the Thermal Convection Effect in NMR Diffusiometry Experiments. Molecules 2022; 27:molecules27196399. [PMID: 36234936 PMCID: PMC9573581 DOI: 10.3390/molecules27196399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/23/2022] [Accepted: 09/24/2022] [Indexed: 12/01/2022] Open
Abstract
Thermal convection is always present when the temperature of an NMR experiment is different from the ambient one. Most often, it falsifies the value of the diffusion coefficient determined by NMR diffusiometry using a PGSE NMR experiment. In spite of common belief, it acts not only at higher temperatures but also at temperatures lower than in the laboratory. Sodium alkyl-sulfate monomers and micelles in D2O solvent were used as model molecules measured at T = 319 K in order to show that thermal convection sometimes remains hidden in experiments. In this paper, we demonstrate that the increase in apparent diffusion coefficient with increasing diffusion time is a definite indicator of thermal convection. Extrapolation to zero diffusion time can also be used to obtain the real diffusion coefficient, likewise applying the less sensitive pulse sequences designed for flow compensation or the expensive hardware, e.g., sapphire or Shigemi NMR tubes, to decrease the temperature gradient. Further, we show experiments illustrating the effect of a long diffusion time in which the periodic changes of the echo intensity with gradient strength appear as predicted by theories.
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3
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Yuan B, Zhou Z, Jiang B, Kamal GM, Zhang X, Li C, Zhou X, Liu M. NMR for Mixture Analysis: Concentration-Ordered Spectroscopy. Anal Chem 2021; 93:9697-9703. [PMID: 34227809 DOI: 10.1021/acs.analchem.1c00831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel approach, concentration-ordered NMR spectroscopy (CORDY), is being proposed based on the principle that the ratio of the NMR peak area to its associated number of spins is proportional to the concentration of the assigned compound. Besides, prior information of chemical shift distribution and line shape characteristics of different chemical groups is utilized to shrink the solution space. CORDY generates a pseudo-two-dimensional NMR spectrum with chemical shifts in one axis and concentrations in the other, resulting in both separation and quantitation of components in complex samples. The method was validated by application to three samples-a model mixture containing six amino acids, sugar-free Red Bull, and human urine. It was demonstrated that CORDY could successfully separate the components with up to 2 orders of magnitude in the concentration dimension for the samples used in the current study. In addition, a combination of CORDY and DOSY (CORDY-DOSY) has been found to be more efficient in resolving the molecules with similar concentrations or self-diffusion coefficients.
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Affiliation(s)
- Bin Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Zhiming Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Bin Jiang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Ghulam Mustafa Kamal
- Department of Chemistry, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan 64200, Pakistan
| | - Xu Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Conggang Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Xin Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China.,University of Chinese Academy of Sciences, Beijing 10049, China
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4
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Schedlbauer A, Iturrioz I, Ochoa-Lizarralde B, Diercks T, López-Alonso JP, Lavin JL, Kaminishi T, Çapuni R, Dhimole N, de Astigarraga E, Gil-Carton D, Fucini P, Connell SR. A conserved rRNA switch is central to decoding site maturation on the small ribosomal subunit. SCIENCE ADVANCES 2021; 7:7/23/eabf7547. [PMID: 34088665 PMCID: PMC8177701 DOI: 10.1126/sciadv.abf7547] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 04/20/2021] [Indexed: 05/03/2023]
Abstract
While a structural description of the molecular mechanisms guiding ribosome assembly in eukaryotic systems is emerging, bacteria use an unrelated core set of assembly factors for which high-resolution structural information is still missing. To address this, we used single-particle cryo-electron microscopy to visualize the effects of bacterial ribosome assembly factors RimP, RbfA, RsmA, and RsgA on the conformational landscape of the 30S ribosomal subunit and obtained eight snapshots representing late steps in the folding of the decoding center. Analysis of these structures identifies a conserved secondary structure switch in the 16S ribosomal RNA central to decoding site maturation and suggests both a sequential order of action and molecular mechanisms for the assembly factors in coordinating and controlling this switch. Structural and mechanistic parallels between bacterial and eukaryotic systems indicate common folding features inherent to all ribosomes.
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Affiliation(s)
- Andreas Schedlbauer
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Idoia Iturrioz
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Borja Ochoa-Lizarralde
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Tammo Diercks
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Jorge Pedro López-Alonso
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | | | - Tatsuya Kaminishi
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
- Department of Genetics, Graduate School of Medicine, Osaka University, Japan
| | - Retina Çapuni
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Neha Dhimole
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Elisa de Astigarraga
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - David Gil-Carton
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain
| | - Paola Fucini
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain.
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Sean R Connell
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Building 801A, 48160 Derio, Spain.
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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5
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Yuan B, Zhang X, Kamal GM, Jiang B, Liu M. Accurate estimation of diffusion coefficient for molecular identification in a complex background. Anal Bioanal Chem 2020; 412:4519-4525. [PMID: 32405677 DOI: 10.1007/s00216-020-02693-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/22/2020] [Accepted: 05/04/2020] [Indexed: 11/25/2022]
Abstract
To eliminate the effects of complex background signals and to enhance the accuracy of the diffusion coefficient measurement, derivative NMR spectroscopy with negligible loss of the spectral quality is introduced based on the customized Savitzky-Golay method and used to construct diffusion-ordered NMR spectroscopy (DOSY). The criterion of the method was established by simulations. The application of this method on mouse urine and serum showed that the accuracy and precision of diffusion coefficient measurements in a complex background were improved to enhance the identification of molecules. Graphical abstract Diffusion-ordered NMR spectroscopy is a powerful tool for analyzing complex mixtures. To improve the accuracy of diffusion coefficient measurement, the magnitude of complex derivative spectra is introduced as a post-processing method to eliminate the effects of background signals, broad signals, or distorted baseline. And thus, accurate estimate of the diffusion coefficient is ensured to enhance the molecule identification.
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Affiliation(s)
- Bin Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
| | - Xu Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Ghulam Mustafa Kamal
- Department of Chemistry, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan, 64200, Pakistan
| | - Bin Jiang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China.
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, Hubei, China.
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
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6
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Swan I, Reid M, Howe PWA, Connell MA, Nilsson M, Moore MA, Morris GA. Sample convection in liquid-state NMR: why it is always with us, and what we can do about it. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:120-129. [PMID: 25681799 DOI: 10.1016/j.jmr.2014.12.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 12/14/2014] [Indexed: 06/04/2023]
Abstract
Many NMR experiments on liquids suffer if the sample convects. This is particularly true for applications, such as the measurement of diffusion, that rely on spatial labelling of spins. It is widely assumed that, in most well-conducted experiments with stable temperature regulation, samples do not convect. Unfortunately this is not the case. It is shown here that typical NMR samples show measurable convective flow for all but a very narrow range of temperatures; convection is seen both above and below this range, which can be as small as a degree or so for a mobile solvent such as chloroform. This convection is driven by both vertical and horizontal temperature gradients. Measurements of convection velocity are presented for a range of samples, sample tubes, probes, and temperatures. Both decreasing sample tube inner diameter and changing sample tube material from glass to sapphire can slow convection markedly, with sapphire tubes being particularly effective. Such tubes are likely to be particularly helpful for accurate measurement of diffusion by NMR.
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Affiliation(s)
- I Swan
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - M Reid
- Syngenta, Jealott's Hill Research Centre, Bracknell RG42 6EY, UK
| | - P W A Howe
- Syngenta, Jealott's Hill Research Centre, Bracknell RG42 6EY, UK
| | - M A Connell
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - M Nilsson
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - M A Moore
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - G A Morris
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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7
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Aguilar JA, Adams RW, Nilsson M, Morris GA. Suppressing exchange effects in diffusion-ordered NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 238:16-19. [PMID: 24263085 DOI: 10.1016/j.jmr.2013.10.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 06/02/2023]
Abstract
In diffusion-ordered spectroscopy (DOSY) the aim is to separate signals from different molecular species according to their different diffusion coefficients. Each species has its individual diffusion coefficient (that may accidentally coincide with that of another species, e.g. if they are of very similar size). In exchanging systems, however, there is a serious complication in that the apparent diffusion coefficient of an exchanging signal will be a compromise that depends, among other factors, on the diffusion coefficients of the exchange partners and the rate of exchange between them. The DOSY spectrum will be much harder to interpret and can often give the appearance of extra (spurious) components in the mixture. Here a new and surprisingly simple experiment is described that suppresses the effects of exchange on apparent diffusion coefficients, restoring the simplicity of interpretation enjoyed by non-exchanging systems.
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Affiliation(s)
- Juan A Aguilar
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
| | - Ralph W Adams
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
| | - Mathias Nilsson
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom; Dept. of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
| | - Gareth A Morris
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
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8
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Al-Husari M, Webb SD. Theoretical predictions of lactate and hydrogen ion distributions in tumours. PLoS One 2013; 8:e72020. [PMID: 23991029 PMCID: PMC3749110 DOI: 10.1371/journal.pone.0072020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 07/11/2013] [Indexed: 11/30/2022] Open
Abstract
High levels of lactate and H(+)-ions play an important role in the invasive and metastatic cascade of some tumours. We develop a mathematical model of cellular pH regulation focusing on the activity of the Na(+)/H(+) exchanger (NHE) and the lactate/H(+) symporter (MCT) to investigate the spatial correlations of extracellular lactate and H(+)-ions. We highlight a crucial role for blood vessel perfusion rates in determining the spatial correlation between these two cations. We also predict critical roles for blood lactate, the activity of the MCTs and NHEs on the direction of the cellular pH gradient in the tumour. We also incorporate experimentally determined heterogeneous distributions of the NHE and MCT transporters. We show that this can give rise to a higher intracellular pH and a lower intracellular lactate but does not affect the direction of the reversed cellular pH gradient or redistribution of protons away from the glycolytic source. On the other hand, including intercellular gap junction communication in our model can give rise to a reversed cellular pH gradient and can influence the levels of pH.
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Affiliation(s)
- Maymona Al-Husari
- Department of Mathematics and Statistics, University of Strathclyde, Glasgow, United Kingdom
| | - Steven D. Webb
- MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, The University of Liverpool, Liverpool, United Kingdom
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9
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Maucler C, Pernot P, Vasylieva N, Pollegioni L, Marinesco S. In vivo D-serine hetero-exchange through alanine-serine-cysteine (ASC) transporters detected by microelectrode biosensors. ACS Chem Neurosci 2013; 4:772-81. [PMID: 23581544 DOI: 10.1021/cn4000549] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
D-serine, a co-agonist of N-methyl D-aspartate (NMDA) receptors, has been implicated in neurological and psychiatric disorders such as cerebral ischemia, lateral amyotrophic sclerosis, or schizophrenia. D-serine signaling represents an important pharmacological target for treating these diseases; however, the biochemical mechanisms controlling extracellular D-serine levels in vivo are still unclear. D-serine heteroexchange through small neutral amino acid transporters has been shown in cell cultures and brain slices and could provide a biochemical mechanism for the control of D-serine extracellular concentration in vivo. Alternatively, exocytotic D-serine release has also been proposed. In this study, the dynamics of D-serine release and clearance were explored in vivo on a second-by-second time scale using microelectrode biosensors. The rate of D-serine clearance in the rat frontal cortex after a microionophoretic injection revealed a transporter-mediated uptake mechanism. D-serine uptake was blocked by small neutral l-amino acids, implicating alanine-serine-cysteine (ASC) transporters, in particular high affinity Asc-1 and low affinity ASCT2 transporters. Interestingly, changes in alanine, serine, or threonine levels resulted in D-serine release through ASC transporters. Asc-1, but not ASCT2, appeared to release D-serine in response to changes in amino acid concentrations. Finally, neuronal silencing by tetrodotoxin increased D-serine extracellular concentration by an ASC-transporter-dependent mechanism. Together, these results indicate that D-serine heteroexchange through ASC transporters is present in vivo and may constitute a key component in the regulation of D-serine extracellular concentration.
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Affiliation(s)
- Caroline Maucler
- INSERM U1028; CNRS UMR5292 Lyon Neuroscience Research Center, AniRA-Neurochem technological platform, team WAKING, Lyon F-69000, France
- Université Claude Bernard Lyon 1, Lyon F-69000, France
| | - Pierre Pernot
- INSERM U1028; CNRS UMR5292 Lyon Neuroscience Research Center, AniRA-Neurochem technological platform, team WAKING, Lyon F-69000, France
- Université Claude Bernard Lyon 1, Lyon F-69000, France
| | - Natalia Vasylieva
- INSERM U1028; CNRS UMR5292 Lyon Neuroscience Research Center, AniRA-Neurochem technological platform, team WAKING, Lyon F-69000, France
- Université Claude Bernard Lyon 1, Lyon F-69000, France
- Institut de nanotechnologie de Lyon, CNRS UMR-5270, INSA de Lyon, France
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell’Insubria, Varese, Italy
- “The Protein Factory”, Centro Interuniversitario di Ricerca in Biotecnologie Proteiche ICRM-CNR Milano, Politecnico di Milano and Università degli studi dell’Insubria, Italy
| | - Stéphane Marinesco
- INSERM U1028; CNRS UMR5292 Lyon Neuroscience Research Center, AniRA-Neurochem technological platform, team WAKING, Lyon F-69000, France
- Université Claude Bernard Lyon 1, Lyon F-69000, France
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10
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Li JV, Saric J, Yap IKS, Utzinger J, Holmes E. Metabonomic investigations of age- and batch-related variations in female NMRI mice using proton nuclear magnetic resonance spectroscopy. MOLECULAR BIOSYSTEMS 2013; 9:3155-65. [DOI: 10.1039/c3mb70215d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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11
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Wang J, Hou T. Application of molecular dynamics simulations in molecular property prediction II: diffusion coefficient. J Comput Chem 2011; 32:3505-19. [PMID: 21953689 PMCID: PMC3193570 DOI: 10.1002/jcc.21939] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/10/2011] [Accepted: 08/14/2011] [Indexed: 11/08/2022]
Abstract
In this work, we have evaluated how well the general assisted model building with energy refinement (AMBER) force field performs in studying the dynamic properties of liquids. Diffusion coefficients (D) have been predicted for 17 solvents, five organic compounds in aqueous solutions, four proteins in aqueous solutions, and nine organic compounds in nonaqueous solutions. An efficient sampling strategy has been proposed and tested in the calculation of the diffusion coefficients of solutes in solutions. There are two major findings of this study. First of all, the diffusion coefficients of organic solutes in aqueous solution can be well predicted: the average unsigned errors and the root mean square errors are 0.137 and 0.171 × 10(-5) cm(-2) s(-1), respectively. Second, although the absolute values of D cannot be predicted, good correlations have been achieved for eight organic solvents with experimental data (R(2) = 0.784), four proteins in aqueous solutions (R(2) = 0.996), and nine organic compounds in nonaqueous solutions (R(2) = 0.834). The temperature dependent behaviors of three solvents, namely, TIP3P water, dimethyl sulfoxide, and cyclohexane have been studied. The major molecular dynamics (MD) settings, such as the sizes of simulation boxes and with/without wrapping the coordinates of MD snapshots into the primary simulation boxes have been explored. We have concluded that our sampling strategy that averaging the mean square displacement collected in multiple short-MD simulations is efficient in predicting diffusion coefficients of solutes at infinite dilution.
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Affiliation(s)
- Junmei Wang
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9050, USA
| | - Tingjun Hou
- Institute of Nano & Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China
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12
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Schug KA, Serrano C, Frycák P. Controlled band dispersion for quantitative binding determination and analysis with electrospray ionization-mass spectrometry. MASS SPECTROMETRY REVIEWS 2010; 29:806-829. [PMID: 19890977 DOI: 10.1002/mas.20267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This review discusses recent emerging techniques that have been used to couple flow-injection analysis (FIA) and electrospray ionization-mass spectrometry (ESI-MS) for the quantitation of noncovalent binding interactions. Focus is placed predominantly on two such methods. Diffusion-based measurements, developed by Konermann and co-workers, uses controlled-band dispersion prior to ESI-MS to determine diffusion constants and binding constants based on the temporal variation of ligand signal measured in the mass spectrum (an indirect technique). Dynamic titration, developed by Schug and co-workers, is a direct method, where a temporal compositional gradient of a guest molecule is induced in the presence of host in solution to monitor the concentration dependence of complex formation as a function of observed complex ion abundance after ESI-MS. Further discussion places these techniques in the context of a variety of other direct and indirect ESI-MS-based binding determination methods, and highlights advantages, disadvantages, and practical considerations for their proper use to investigate a broad range of macromolecular and small-molecule interaction systems.
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Affiliation(s)
- Kevin A Schug
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019-0065, USA.
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13
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Yang S, Zhang Y, Liao T, Guo Z, Chen Y. Electromigration diffusivity spectrometry: A way for simultaneous determination of diffusion coefficients from mixed samples. Electrophoresis 2010; 31:2949-56. [DOI: 10.1002/elps.201000252] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Li F, Wang L, Xiao N, Yang M, Jiang L, Liu M. Dominant Conformation of Valsartan in Sodium Dodecyl Sulfate Micelle Environment. J Phys Chem B 2010; 114:2719-27. [DOI: 10.1021/jp908958k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fang Li
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Lingyun Wang
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Nan Xiao
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Minghui Yang
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Ling Jiang
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Maili Liu
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China, and Graduate School, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
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15
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Zheng G, Price WS. Simultaneous convection compensation and solvent suppression in biomolecular NMR diffusion experiments. JOURNAL OF BIOMOLECULAR NMR 2009; 45:295-299. [PMID: 19697137 DOI: 10.1007/s10858-009-9367-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 08/04/2009] [Indexed: 05/28/2023]
Abstract
Thermal convection and high intensity solvent resonances can significantly hamper diffusion estimates in pulsed gradient spin-echo nuclear magnetic resonance diffusion experiments on biomolecule samples. To overcome these two problems, a new double functional NMR diffusion sequence, double echo PGSTE-WATERGATE, is presented. The new sequence provides excellent convection compensation and solvent suppression (with a suppression factor in excess of at least 10(5) in a single scan) in biomolecular NMR diffusion experiments. Due to its stimulated echo nature, the new sequence is much less susceptible to spin-spin relaxation than Hahn spin-echo based sequences. Furthermore, the new sequence is not susceptible to spin diffusion due to the application of bipolar pulsed gradients. The new sequence is also much easier to set up compared to previously developed stimulated echo based convection compensation and solvent suppression sequence. The utility of the new sequence is demonstrated on an aqueous lysozyme sample.
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Affiliation(s)
- Gang Zheng
- Nanoscale Organisation and Dynamics Group, College of Health and Science, University of Western Sydney, Penrith South DC, NSW, 1797, Australia
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16
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Occhipinti P, Griffiths PC. Quantifying diffusion in mucosal systems by pulsed-gradient spin-echo NMR. Adv Drug Deliv Rev 2008; 60:1570-82. [PMID: 18940211 DOI: 10.1016/j.addr.2008.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 08/28/2008] [Indexed: 01/22/2023]
Abstract
Mucus, a thick and slimy secretion produced by submucosal cells, covers many epithelial surfaces in mammalian organs and prevents foreign particles that enter the body from accessing cells. However, the mucus layer also represents a potential barrier to the efficient delivery of nano-sized drug delivery systems (polyplexes, lipoplexes, particles) to the underlying mucosal epithelium. Many studies have considered the ability of nano-sized particles and polymers to diffuse within the mucosal network using a range of different techniques, including multiple-particle tracking (MPT), diffusion chamber studies and fluorescence recovery after photobleaching (FRAP). This review highlights the current understanding of the interaction of the diffusion of nano-sized structures within mucosal networks. Moreover, this article presents an introduction to pulsed-gradient spin-echo NMR (PGSE-NMR), a potential new tool to investigate the mobility of molecular species through mucosal networks and related biological gels.
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Affiliation(s)
- Paola Occhipinti
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
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17
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Zheng G, Price WS. MAG-PGSTE: a new STE-based PGSE NMR sequence for the determination of diffusion in magnetically inhomogeneous samples. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 195:40-44. [PMID: 18774320 DOI: 10.1016/j.jmr.2008.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 08/05/2008] [Accepted: 08/11/2008] [Indexed: 05/26/2023]
Abstract
A new stimulated echo based pulsed gradient spin-echo sequence, MAG-PGSTE, has been developed for the determination of self-diffusion in magnetically inhomogeneous samples. The sequence was tested on two glass bead samples (i.e., 212-300 and <106 microm glass bead packs). The MAG-PGSTE sequence was compared to the MAGSTE (or MPFG) (P.Z. Sun, J.G. Seland, D. Cory, Background gradient suppression in pulsed gradient stimulated echo measurements, J. Magn. Reson. 161 (2003) 168-173; P.Z. Sun, S.A. Smith, J. Zhou, Analysis of the magic asymmetric gradient stimulated echo sequence with shaped gradients, J. Magn. Reson. 171 (2004) 324-329; P.Z. Sun, Improved diffusion measurement in heterogeneous systems using the magic asymmetric gradient stimulated echo (MAGSTE) technique, J. Magn. Reson. 187 (2007) 177-183; P. Galvosas, F. Stallmach, J. Kärger, Background gradient suppression in stimulated echo NMR diffusion studies using magic pulsed field gradient ratios, J. Magn. Reson. 166 (2004) 164-173, P. Galvosas, PFG NMR-Diffusionsuntersuchungen mit ultra-hohen gepulsten magnetischen Feldgradienten an mikroporösen Materialien, Ph.D. Thesis, Universität Leipzig, 2003, P.Z. Sun, Nuclear Magnetic Resonance Microscopy and Diffusion, Ph.D. Thesis, Massachusetts Institute of Technology, 2003] sequence and Cotts 13-interval [R.M. Cotts, M.J.R. Hoch, T. Sun, J.T. Marker, Pulsed field gradient stimulated echo methods for improved NMR diffusion measurements in heterogeneous systems, J. Magn. Reson. 83 (1989) 252-266] sequence using both glass bead samples. The MAG-PGSTE and MAGSTE (or MPFG) sequences outperformed the Cotts 13-interval sequence in the measurement of diffusion coefficients; more interestingly, for the sample with higher background gradients (i.e., the <106 microm glass bead sample), the MAG-PGSTE sequence provided higher signal-to-noise ratios and thus better diffusion measurements than the MAGSTE and Cotts 13-interval sequences. In addition, the MAG-PGSTE sequence provided good characterization of the surface-to-volume ratio for the glass bead samples.
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Affiliation(s)
- Gang Zheng
- Nanoscale Organisation and Dynamics Group, College of Health and Science, University of Western Sydney, Penrith South DC, NSW 1797, Australia
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18
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LAN WX, ZHU H, LIU ML. Separating Human Serums of Health and Hyperlipidaemia Subjects Using Diffusion-weighted Nuclear Magnetic Resonance Spectroscopy. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2008. [DOI: 10.1016/s1872-2040(08)60049-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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19
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Chatterjee C, Gerig JT. Interactions of Hexafluoro-2-propanol with the Trp-Cage Peptide†. Biochemistry 2006; 45:14665-74. [PMID: 17144659 DOI: 10.1021/bi061750+] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluoro alcohols present in aqueous solutions can alter the dominant conformations of peptides and proteins. The origins of these effects likely are related to the details of solute-fluoro alcohol interactions. Preferential interaction of the fluoro alcohol component of a fluoro alcohol-water mixture with peptide solutes has been demonstrated by several experimental approaches. In the present work, we have used 1H{19F} intermolecular NOE experiments to examine interactions of hexafluoro-2-propanol in a 30% fluoro alcohol-50 mM phosphate buffer solvent mixture with the "Trp-cage" peptide (NLY IQW LKD GGP SSG RPP PS). The results show that the peptide is selectively solvated by hexafluoro-2-propanol to the extent that the fluoro alcohol concentration near the peptide may be 3 to 4 times higher than the nominal concentration of fluoro alcohol in the bulk sample. The observed NOEs indicate that peptide-fluoro alcohol interactions persist for times of the order of 1 ns at 5 degrees C. As the sample temperature is increased, the lifetimes of fluoro alcohol interactions with several exposed side chains decrease to the extent that the peptide hydrogen-solvent fluorine interactions appear to become diffusive in nature, with interaction lifetimes of approximately 0.03 ns. It is known that protein molecules can provide specific sites for binding small organic solvent molecules. Our work suggests that small peptides also have this ability and that the dynamics for such interactions can be site-specific.
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Affiliation(s)
- Chiradip Chatterjee
- Department of Chemistry and Biochemistry, University of California. Santa Barbara, California 93106, USA
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20
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Vandenbussche S, Vandenbussche G, Reisse J, Bartik K. Do Serine Octamers Exist in Solution? Relevance of this Question in the Context of the Origin of Homochirality on Earth. European J Org Chem 2006. [DOI: 10.1002/ejoc.200600370] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Hovagimyan KG, Gerig JT. Interactions of TrimethylamineN−Oxide and Water withcyclo-Alanylglycine. J Phys Chem B 2005; 109:24142-51. [PMID: 16375406 DOI: 10.1021/jp055075+] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The osmolyte trimethylamine N-oxide (TMAO) is one of a family of compounds found in living systems that can stabilize biomolecular tertiary structures. As a step in exploring the interactions between this material and polyamino acids, we have determined intermolecular 1H{1H} nuclear Overhauser effects (NOEs) between the protons of cyclo-alanylglycine and protons of solvent components in TMAO-water solutions. Comparison of the results to effects predicted on the basis of the molecular shape of the dipeptide and experimental translational diffusion coefficients suggests that both water and TMAO molecules have properties in the vicinity of the dipeptide that are different from those in the bulk solution. Changes of local concentrations of water and TMAO and changes in the diffusive behavior of these components near the dipeptide are rejected as possible explanations of the discrepancies between observed and calculated Overhauser effects. Rather, it is concluded that TMAO molecules, and the water molecules associated with them, participate to some extent in the formation of long-lived solute-solvent complexes. The aliphatic alcohol tert-butyl alcohol is structurally similar to TMAO. Overhauser effect studies of its interaction with cyclo-alanylglycine in tert-butyl alcohol-water suggest similar kinds of interactions are present in this system but that they are significantly weaker, presumably because of the lower polarity of this alcohol compared to TMAO.
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Affiliation(s)
- Karen G Hovagimyan
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, USA
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22
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Lucas LH, Larive CK, Wilkinson PS, Huhn S. Progress toward automated metabolic profiling of human serum: Comparison of CPMG and gradient-filtered NMR analytical methods. J Pharm Biomed Anal 2005; 39:156-63. [PMID: 15890484 DOI: 10.1016/j.jpba.2004.09.060] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2004] [Indexed: 11/29/2022]
Abstract
The investigation of drug delivery and metabolism requires the analysis of molecules in complicated biological matrices such as human serum. In NMR-based metabonomic analysis, T(2) relaxation editing with a CPMG filter is commonly used to suppress background signals from proteins and other endogenous components. Radio frequency pulse imperfections and incomplete irradiation across the spectral bandwidth can cause phase and baseline distortions in CPMG spectra. These distortions are exacerbated by water suppression techniques. Baseline correction methods included in commercially available data processing software packages may be incapable of producing artifact-free spectra. To increase the analytical precision of metabolic profiling, one NMR spectroscopist may be responsible for manually phasing and baseline correcting hundreds of spectra individually to remove operator-dependent variations, significantly reducing throughput. For metabonomic analysis of human serum, it was observed that the application of a pulsed field gradient filter produced (1)H NMR spectra well suited to automatic phasing routines. Superior baseline characteristics, an increased tolerance to radio frequency pulse imperfections, and improved water suppression were achieved. A concomitant reduction in signal intensity compared with the CPMG method was easily recovered by increasing the number of scans. Principal component analysis (PCA) of spectra, acquired under a variety of experimental conditions, revealed the improved reproducibility and robustness of (1)H NMR pulsed field gradient-filtered metabonomic analyses of serum compared to the CPMG method.
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Affiliation(s)
- Laura H Lucas
- Department of Chemistry, University of Kansas, Malott Hall, Lawrence, 66045, USA
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23
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Yang Y, Bai G, Zhang X, Ye C, Liu M. 1H NMR spectroscopic evidence of interaction between ibuprofen and lipoproteins in human blood plasma. Anal Biochem 2004; 324:292-7. [PMID: 14690694 DOI: 10.1016/j.ab.2003.10.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent studies have suggested that ibuprofen inhibits low-density lipoprotein oxidation in a high dose-dependent manner and is a promising drug for treatment of the conditions associated with atherosclerosis. In this article, we present the NMR spectroscopic evidence for the interaction between ibuprofen and phospholipids in lipoprotein particles in intact human plasma. Ibuprofen caused chemical shift upfield drifts for the protons of -N(+)(CH(3))(3) moieties of phosphatidylcholine and sphingomyelin, olefinic chains (-CH[double bond]CH[bond], [bond]CH[triple bond]CHCH(2)CH[triple bond]CH[bond], [bond](CH(2))(n)CH(2)CH[double bond]), and (CH(2))(n) and CH(3) groups, from unsaturated lipids in lipoprotein particles. The ibuprofen may interact directly with the above-mentioned groups of phospholipids or induce structural changes in the lipoproteins. This may shed light on the mechanism by which the drug protects against oxidative modification of lipoproteins.
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Affiliation(s)
- Yunhuang Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
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24
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Hayamizu K, Price WS. A new type of sample tube for reducing convection effects in PGSE-NMR measurements of self-diffusion coefficients of liquid samples. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2004; 167:328-333. [PMID: 15040990 DOI: 10.1016/j.jmr.2004.01.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Revised: 01/12/2004] [Indexed: 05/24/2023]
Abstract
Pulsed gradient spin-echo (PGSE) NMR measurements of the self-diffusion coefficients of low viscosity liquids are greatly hampered by the effects of convection especially away from ambient temperature. Here we report on a new NMR tube designed to minimize the deleterious effects of convection. In this tube, which derives from a Shigemi symmetrical NMR tube, the sample is contained in an annulus formed from a concentric cylinder of susceptibility matched glass. The performance of this tube was demonstrated by conducting measurements on the electrochemically important LiN(SO3CF3)2 (LiTFSI)-diglyme (DG) system. Calibrations were first made using DG at column heights of 2, 3, and 4-mm in the temperature range between -40 and 100 degrees C. Measurements of the diffusion coefficients of the lithium, anion, and DG were then performed to probe the solvent-ion and ion-ion interactions in the DG doped with LiTFSI. Changes in the 1H, 7Li, and 19F PGSE-NMR attenuation curves at -40 degrees C provided clear evidence of interactions between the DG and lithium ion.
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Affiliation(s)
- Kikuko Hayamizu
- National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Center 5, Tsukuba 305-8565, Japan.
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25
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Clark SM, Leaist DG, Konermann L. Taylor dispersion monitored by electrospray mass spectrometry: a novel approach for studying diffusion in solution. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2002; 16:1454-1462. [PMID: 12125022 DOI: 10.1002/rcm.732] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This work describes a novel approach for monitoring analyte diffusion in solution that is based on electrospray ionization mass spectrometry (ESI-MS). A mass spectrometer at the end of a laminar flow tube is used to measure the Taylor dispersion of an initially sharp boundary between two solutions of different analyte concentration. This boundary is dispersed by the laminar flow profile in the tube. However, this effect is diminished by analyte diffusion that continuously changes the radial position, and hence the flow velocity of individual analyte molecules. The steepness of the resulting dispersion profile therefore increases with increasing diffusion coefficient of the analyte. A theoretical framework is developed to adapt the equations governing the dispersion process to the case of mass spectrometric detection. This novel technique is applied to determine the diffusion coefficients of choline and cytochrome c. The measured diffusion coefficients, (11.9 +/- 1.0) x 10(-10) m(2) s(-1) and (1.35 +/- 0.08) x 10(-10) m(2) s(-1), respectively, are in agreement with the results of control experiments where the Taylor dispersion of these two analytes was monitored optically. Due to the inherent selectivity and sensitivity of ESI-MS, it appears that the approach described in this work could become a valuable alternative to existing methods for studying diffusion processes, especially for experiments on multicomponent systems.
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Affiliation(s)
- Sonya M Clark
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
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