Heteronuclear relaxation in time-dependent spin systems: 15N-T1ρ dispersion during adiabatic fast passage

International Nuclear Information System (INIS)

Konrat, Robert; Tollinger, Martin

1999-01-01

A novel NMR experiment comprising adiabatic fast passage techniques for the measurement of heteronuclear self-relaxation rates in fully 15N-enriched proteins is described. Heteronuclear self-relaxation is monitored by performing adiabatic fast passage (AFP) experiments at variable adiabaticity (e.g., variation of RF spin-lock field intensity). The experiment encompasses gradient- selection and sensitivity-enhancement. It is shown that transverse relaxation rates derived with this method are in good agreement with the ones measured by the classical Carr-Purcell-Meiboom-Gill (CPMG) sequences. An application of this method to the study of the carboxyl-terminal LIM domain of quail cysteine and glycine-rich protein qCRP2(LIM2) is presented

Novel multi-dimensional heteronuclear NMR techniques for the study of 13C-O-acetylated oligosaccharides: Expanding the dimensions for carbohydrate structures

Energy Technology Data Exchange (ETDEWEB)

Jones, David N.M. [University of Colorado Health Sciences Center, Departments of Pharmacology (United States); Bendiak, Brad [University of Colorado Health Sciences Center, Departments of Cellular and Structural Biology (United States)

1999-10-15

Complex carbohydrates have critical roles in a wide variety of biological processes. An understanding of the molecular mechanisms that underlie these processes is essential in the development of novel oligosaccharide-based therapeutic strategies. Unfortunately, obtaining detailed structural information for larger oligosaccharides (>10 residues) can be exceedingly difficult, especially where the amount of sample available is limited. Here we demonstrate the application of {sup 13} C O-acetylation in combination with novel NMR experiments to obtain much of the information required to characterize the primary structure of oligosaccharides. (H)C{sub Me}COH-HEHAHA and H(C{sub Me})COH-HEHAHA experiments are presented that use heteronuclear Hartmann-Hahn transfer to correlate the acetyl groups with sugar ring protons in peracetylated oligosaccharides. The in-phase, pure absorption nature of the correlation peaks in these experiments allows measurement of both chemical shifts and, importantly, {sup 1}H-{sup 1}H coupling constants that are used to define the stereochemistry of the sugar ring. The (HC{sub Me})COH and (HC{sub Me})COH-RELAY experiments provide additional methods for obtaining chemical shift assignments for larger oligosaccharides to define the sites of glycosidic linkages from the patterns of acetylation.

Structural study of pyrones by NMR

International Nuclear Information System (INIS)

Mandarino, D.G.

1985-01-01

Extracts of two species of Aniba, designed Aniba-SA (light petroleum extract) and Aniba-SB (benzene extract), afforded by chromatographic fraccionation some compounds. The isolated compounds were identified using spectrometric data and C 13 -NMR coupled and decompled spectra of pyrones were registered. Measurement of the heteronuclear residual coupling by irradiation proton frequency off-resonance was used for distinguish C-5, C-7 and C-8 carbons of the pyrones SB-1, SB-3, SB-4 and SB-5. (M.J.C.) [pt

Heteronuclear long-range correlation, what’s new and how far can it take us?

DEFF Research Database (Denmark)

Sørensen, Ole W.

: A novel experiment for small-molecule and biomolecular NMR at natural isotopic abundance. Sebastian Meier, Andrew J. Benie, Jens Ø. Duus and Ole W. Sørensen, Journal of Magnetic Resonance, in press, doi:10.1016/j.jmr.2009.06.017 Recent progress in heteronuclear long-range NMR of complex carbohydrates: 3D...... H2BC and clean HMBC. Sebastian Meier, Bent O. Petersen, Jens Ø. Duus, Ole W. Sørensen. Carbohydrate Research, in press, doi:10.1016/j.carres.2009.08.013...

Quantum theory of NMR adiabatic pulses and their applications

International Nuclear Information System (INIS)

Ke, Y.

1993-01-01

Recently explosive developments of in vivo NMR spectroscopy (NMRS) and imaging (NMRI) in biological and medical sciences have resulted in the establishment of NMR as one of the most advanced major technique in life sciences. These developments have created huge demands for a variety of NMR adiabatic pulses with play a very important role in NMR experiments in vivo. In order to develop new NMR adiabatic pulses, a rigorous systematical quantum theory for this kind of pulses is greatly needed. Providing such a theory is one of the important goals of this dissertation. Quantum density matrix theory and product operator method have been used throughout this dissertation. Another goal, which is the major goal of this thesis research, is to use the quantum theory as a guide to develop new NMR adiabatic pulses and their applications. To fill this goal, a technique to construct a new type of adiabatic pulses, narrow band selective adiabatic pulses, has been invented, which is described through the example of constructing an adiabatic DANTE inversion pulse. This new adiabatic pulse is the first narrow band selective adiabatic pulses: Adiabatic homonuclear and heteronuclear spectral editing sequences. Unique to the first pulse sequence is a B 1 -field filter which is built by using two non-refocusing adiabatic full passage pulses to refocus the wanted signal and dephase unwanted signals. This extra filter greatly enhance the editing efficiency. Unlike commonly used heteronuclear spectral editing sequences which depend on the polarization transfer or spectral subtraction by phase cycling techniques, the second pulse sequences accomplishes the editing of heteronuclear J-coupled signals based on the fact that this sequence is transparent to the uncoupled spins and is equivalent a 90 degrees excitation pulse to the heteronuclear J-coupled spins. Experimental results have confirmed the ability of spectral editing with these two new sequences

Structural studies of bacterial transcriptional regulatory proteins by multidimensional heteronuclear NMR

Energy Technology Data Exchange (ETDEWEB)

Volkman, Brian Finley [Univ. of California, Berkeley, CA (United States)

1995-02-01

Nuclear magnetic resonance spectroscopy was used to elucidate detailed structural information for peptide and protein molecules. A small peptide was designed and synthesized, and its three-dimensional structure was calculated using distance information derived from two-dimensional NMR measurements. The peptide was used to induce antibodies in mice, and the cross-reactivity of the antibodies with a related protein was analyzed with enzyme-linked immunosorbent assays. Two proteins which are involved in regulation of transcription in bacteria were also studied. The ferric uptake regulation (Fur) protein is a metal-dependent repressor which controls iron uptake in bacteria. Two- and three-dimensional NMR techniques, coupled with uniform and selective isotope labeling allowed the nearly complete assignment of the resonances of the metal-binding domain of the Fur protein. NTRC is a transcriptional enhancer binding protein whose N-terminal domain is a "receiver domain" in the family of "two-component" regulatory systems. Phosphorylation of the N-terminal domain of NTRC activates the initiation of transcription of aeries encoding proteins involved in nitrogen regulation. Three- and four-dimensional NMR spectroscopy methods have been used to complete the resonance assignments and determine the solution structure of the N-terminal receiver domain of the NTRC protein. Comparison of the solution structure of the NTRC receiver domain with the crystal structures of the homologous protein CheY reveals a very similar fold, with the only significant difference being the position of helix 4 relative to the rest of the protein. The determination of the structure of the NTRC receiver domain is the first step toward understanding a mechanism of signal transduction which is common to many bacterial regulatory systems.

NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning

Energy Technology Data Exchange (ETDEWEB)

Shmyreva, Anna A. [Center for Magnetic Resonance, St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Safdari, Majid; Furó, István [Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm (Sweden); Dvinskikh, Sergey V., E-mail: sergeid@kth.se [Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm (Sweden); Laboratory of Biomolecular NMR, St. Petersburg State University, St. Petersburg 199034 (Russian Federation)

2016-06-14

Orders of magnitude decrease of {sup 207}Pb and {sup 199}Hg NMR longitudinal relaxation times T{sub 1} upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX{sub 2} (Me = Pb, Hg and X = Cl, Br, I). In lead(II) halides, the most dramatic decrease of T{sub 1} relative to that in a static sample is in PbI{sub 2}, while it is smaller but still significant in PbBr{sub 2}, and not detectable in PbCl{sub 2}. The effect is magnetic-field dependent but independent of the spinning speed in the range 200–15 000 Hz. The observed relaxation enhancement is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time.

Selected topics from recent NMR studies of organolithium compounds

Directory of Open Access Journals (Sweden)

Günther Harald

1999-01-01

Full Text Available After a short introduction to NMR spectroscopy of alkali and alkaline earth metals the review concentrates on NMR investigations of organolithium compounds. The isotopic fingerprint method, which rests on deuterium-induced isotope shifts for 6Li resonances, is introduced and exemplified with applications from the aggregation behavior of cyclopropyllithium systems and mixed aggregate formation between methyllithium and lithium salts. In the following chapter, one- and two-dimensional pulse experiments, both for homo- and for heteronuclear spin systems are discussed. Finally, the structural aspects associated with benzyllithium are outlined and the formation of polylithium systems by lithium reduction of biphenylenes is described.

Heteronuclear cross-polarization in multinuclear multidimensional NMR: Prospects for triple-resonance CP

Energy Technology Data Exchange (ETDEWEB)

Majumdar, A.; Zuiderweg, E.R.P. [Univ. of Michigan, Ann Arbor, MI (United States)

1994-12-01

Heteronuclear multiple-pulse-based Cross Polarization (HECP) between scalar coupled spins is gaining an important role in high-resolution multidimensional NMR of isotopically labeled biomolecules, especially in experiments involving net magnetization transfer. It has generally been observed that in these situations, the performance of HECP is superior to that of INEPT-based sequences. In particular, HECP-based three-dimensional HCCH spectroscopy is more efficient than the INEPT version of the same experiment. Differences in sensitivity have been intuitively attributed to relaxation effects and technical factors such as radiofrequency (rf) inhomogeneity We present theoretical analyses and computer simulations to probe the effects of these factors. Relaxation effects were treated phenomenologically; we found that relaxation differences are relatively small (up to 25%) between pulsed-free-precession (INEPT) and HECP-although always in favor of HECP. We explored the rf effects by employing a Gaussian distribution of rf amplitude over sample volume. We found that inhomogeneity effects significantly favor HECP over INEPT, especially under conditions of {open_quotes}matched {close_quotes} inhomogeneity in the two rf coils. The differences in favor of HECP indicate that an extension of HECP to triple resonance experiments (TRCP) in I -> S -> Q net transfers might yield better results relative to analogous INEPT-based net transfers. We theoretically analyze the possibilities of TRCP and find that transfer functions are critically dependent on the ratio J{sub IS}/J{sub SQ}. When J{sub IS} equals J{sub SQ}, we find that 100% transfer is possible for truly simultaneous TRCP and this transfer is obtained in a time 1.41 /J. The TRCP time requirement compares favorably with optimally concatenated INEPT-transfers, where net transfer I -> S -> Q is complete at 1.5 /J.

Structural Studies of Bcl-xL/ligand Complexes using {sup 19}F NMR

Energy Technology Data Exchange (ETDEWEB)

Yu Liping; Hajduk, Philip J.; Mack, Jamey; Olejniczak, Edward T. [GPRD, Abbott Laboratories, Pharmaceutical Discovery Division (United States)], E-mail: Edward.olejniczak@abbott.com

2006-04-15

Fluorine atoms are often incorporated into drug molecules as part of the lead optimization process in order to improve affinity or modify undesirable metabolic and pharmacokinetic profiles. From an NMR perspective, the abundance of fluorinated drug leads provides an exploitable niche for structural studies using {sup 19}F NMR in the drug discovery process. As {sup 19}F has no interfering background signal from biological sources, {sup 19}F NMR studies of fluorinated drugs bound to their protein receptors can yield easily interpretable and unambiguous structural constraints. {sup 19}F can also be selectively incorporated into proteins to obtain additional constraints for structural studies. Despite these advantages, {sup 19}F NMR has rarely been exploited for structural studies due to its broad lines in macromolecules and their ligand complexes, leading to weak signals in {sup 1}H/{sup 19}F heteronuclear NOE experiments. Here we demonstrate several different experimental strategies that use {sup 19}F NMR to obtain ligand-protein structural constraints for ligands bound to the anti-apoptotic protein Bcl-xL, a drug target for anti-cancer therapy. These examples indicate the applicability of these methods to typical structural problems encountered in the drug development process.

Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

Science.gov (United States)

Kupka, Teobald; Wieczorek, Piotr P.

2016-01-01

In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of 1H and 13C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

Carbon-13 NMR spectroscopy of biological systems

CERN Document Server

Beckmann, Nicolau

1995-01-01

This book is intended to provide an in-depth understanding of 13C NMR as a tool in biological research. 13C NMR has provided unique information concerning complex biological systems, from proteins and nucleic acids to animals and humans. The subjects addressed include multidimensional heteronuclear techniques for structural studies of molecules in the liquid and solid states, the investigation of interactions in model membranes, the elucidation of metabolic pathwaysin vitro and in vivo on animals, and noninvasive metabolic studies performed on humans. The book is a unique mix of NMR methods and biological applications which makes it a convenient reference for those interested in research in this interdisciplinary area of physics, chemistry, biology, and medicine.Key Features* An interdisciplinary text with emphasis on both 13C NMR methodology and the relevant biological and biomedical issues* State-of-the-art 13C NMR techniques are described; Whenever possible, their advantages over other approaches are empha...

Detailed 1H and 13C NMR spectral data assignment for two dihydrobenzofuran neolignans

International Nuclear Information System (INIS)

Medeiros, Talita C.T.; Dias, Herbert J.; Crotti, Antônio E.M.

2016-01-01

In this work we present a complete proton ( 1 H) and carbon 13 ( 13 C) nuclear magnetic resonance (NMR) spectral analysis of two synthetic dihydrofuran neolignans (±)-trans-dehydrodicoumarate dimethyl ester and (±)-trans-dehydrodiferulate dimethyl ester. Unequivocal assignments were achieved by 1 H NMR, proton decoupled 13 C ( 13 C{ 1 H}) NMR spectra, gradient-selected correlation spectroscopy (gCOSY), J-resolved, gradient-selected heteronuclear multiple quantum coherence (gHMQC), gradient-selected heteronuclear multiple bond coherence (gHMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. All hydrogen coupling constants were measured, clarifying all the hydrogen signals multiplicities. Computational methods were also used to simulate the 1 H and 13 C chemical shifts and showed good agreement with the trans configuration of the substituents at C 7 and C 8 . (author)

Two dimensional solid state NMR

International Nuclear Information System (INIS)

Kentgens, A.P.M.

1987-01-01

This thesis illustrates, by discussing some existing and newly developed 2D solid state experiments, that two-dimensional NMR of solids is a useful and important extension of NMR techniques. Chapter 1 gives an overview of spin interactions and averaging techniques important in solid state NMR. As 2D NMR is already an established technique in solutions, only the basics of two dimensional NMR are presented in chapter 2, with an emphasis on the aspects important for solid spectra. The following chapters discuss the theoretical background and applications of specific 2D solid state experiments. An application of 2D-J resolved NMR, analogous to J-resolved spectroscopy in solutions, to natural rubber is given in chapter 3. In chapter 4 the anisotropic chemical shift is mapped out against the heteronuclear dipolar interaction to obtain information about the orientation of the shielding tensor in poly-(oxymethylene). Chapter 5 concentrates on the study of super-slow molecular motions in polymers using a variant of the 2D exchange experiment developed by us. Finally chapter 6 discusses a new experiment, 2D nutation NMR, which makes it possible to study the quadrupole interaction of half-integer spins. 230 refs.; 48 figs.; 8 tabs

Solution NMR study of the yeast cytochrome c peroxidase: cytochrome c interaction

Energy Technology Data Exchange (ETDEWEB)

Volkov, Alexander N., E-mail: ovolkov@vub.ac.be; Nuland, Nico A. J. van [Vrije Universiteit Brussel, Jean Jeener NMR Centre, Structural Biology Brussels (Belgium)

2013-07-15

Here we present a solution NMR study of the complex between yeast cytochrome c (Cc) and cytochrome c peroxidase (CcP), a paradigm for understanding the biological electron transfer. Performed for the first time, the CcP-observed heteronuclear NMR experiments were used to probe the Cc binding in solution. Combining the Cc- and CcP-detected experiments, the binding interface on both proteins was mapped out, confirming that the X-ray structure of the complex is maintained in solution. Using NMR titrations and chemical shift perturbation analysis, we show that the interaction is independent of the CcP spin-state and is only weakly affected by the Cc redox state. Based on these findings, we argue that the complex of the ferrous Cc and the cyanide-bound CcP is a good mimic of the catalytically-active Cc-CcP compound I species. Finally, no chemical shift perturbations due to the Cc binding at the low-affinity CcP site were observed at low ionic strength. We discuss possible reasons for the absence of the effects and outline future research directions.

Analysis of the backbone dynamics of interleukin-1β using two-dimensional inverse detected heteronuclear 15N-1H NMR spectroscopy

International Nuclear Information System (INIS)

Clore, G.M.; Driscoll, P.C.; Wingfield, P.T.; Gronenborn, A.M.

1990-01-01

The backbone dynamics of uniformly 15 N-labeled interleukin-1β are investigated by using two-dimensional inverse detected heteronuclear 15 N- 1 H NMR spectroscopy. 15 N T 1 , T 2 , and NOE data at a spectrometer frequency of 600 MHz are obtained for 90% of the backbone amide groups. The data provide evidence for motions on three time scales. All the residues exhibit very fast motions on a time scale of approx-lt 20-50 ps that can be characterized by a single-order parameter with an average value of 0.82 ± 0.05. Thirty-two residues also display motions on a time scale of 0.5-4 ns, slightly less than the overall rotational correlation time of the protein (8.3 ns). While the simple formulation can account for the 15 N T 1 and T 2 data, it fails to account for the 15 N- 1 H NOE data and yields calculated values for the NOEs that are either too small or negative, whereas the observed NOEs are positive. Another 42 residues are characterized by some sort of motion on the 30-ns-10-ms time scale, which results in 15 N line broadening due to chemical exchange between different conformational substates with distinct 15 N chemical shifts. In general, the motions on both the 0.5-4-ns and 30-ns-10-ms time scales are localized in surface-accessible loops and turns connecting the β-strands, as well as at the beginning and end of strands. Finally, the kinetic and equilibrium properties of a slow conformational equilibrium between a major and a minor species, involving at least 19 residues and located on one contiguous face of the molecule, are characterized by using 1 H- 15 N correlation spectroscopy, 1 H- 15 N heteronuclear multiple quantum coherence-nuclear Overhauser enhancement spectroscopy, and 1 H- 1 H nuclear Overhauser enhancement spectroscopy

Adiabatic Low-Pass J Filters for Artifact Suppression in Heteronuclear NMR

DEFF Research Database (Denmark)

Meier, Sebastian; Benie, Andrew J; Duus, Jens Øllgaard

2009-01-01

NMR artifact purging: Modern NMR experiments depend on efficient coherence transfer pathways for their sensitivity and on suppression of undesired pathways leading to artifacts for their spectral clarity. A novel robust adiabatic element suppresses hard-to-get-at artifacts....

Application of heteronuclear couplings to conformational analysis of oligonucleotides

International Nuclear Information System (INIS)

Zhu, G.; Live, D.; Bax, A.

1994-01-01

The value of vicinal coupling constants extracted from NMR spectra in deducing torsion angles for conformational analysis is well recognized. Due to the abundance of protons, their couplings have been mostly widely used. In many instances, couplings between protons and other nuclei may be a valuable complement to proton-proton couplings or, in some instances, may be the only coupling available to characterize the torsion angle about a bond. Recently, heteronuclear couplings have been used to great benefit in studies of isotopically enriched proteins, and this general approach has been extended to peptides at natural abundance. The possibility of using this approach to study oligonucleotides is also attractive but has not as yet been widely exploited. With the development of strategies for labeling such molecules, particularly RNAs, this may become an important component in conformational analysis. For DNA, labeling is less accessible, but sufficient quantities of unlabeled material are readily available for measuring these couplings at natural abundance. We chose several DNA systems to explore the usefulness of heteronuclear couplings in addressing the sugar conformation and the glycosidic torsion angle. Intensities of cross peaks in long-range HMQC experiments can be related to the couplings. Crosspeaks involving H1' and C1' atoms have been emphasized because of the superior shift dispersion at these positions between sugar protons and carbon atoms. Results will be shown for the self-complementary Dickerson duplex dodecamer sequence d(CGCGAATTCGCG) and for d(GGTCGG), which dimerizes to form a G-tetrad structure incorporating both syn and anti base orientations. The couplings provide a clear discrimination between presence of C3'-endo and C2'-endo conformations of the sugars and syn and anti bases arrangements

Application of heteronuclear couplings to conformational analysis of oligonucleotides

Energy Technology Data Exchange (ETDEWEB)

Zhu, G. [Univ. of Maryland, College Park, MD (United States); Live, D. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Bax, A. [NIDDK National Institutes of Health, Bethesda, MD (United States)

1994-12-01

The value of vicinal coupling constants extracted from NMR spectra in deducing torsion angles for conformational analysis is well recognized. Due to the abundance of protons, their couplings have been mostly widely used. In many instances, couplings between protons and other nuclei may be a valuable complement to proton-proton couplings or, in some instances, may be the only coupling available to characterize the torsion angle about a bond. Recently, heteronuclear couplings have been used to great benefit in studies of isotopically enriched proteins, and this general approach has been extended to peptides at natural abundance. The possibility of using this approach to study oligonucleotides is also attractive but has not as yet been widely exploited. With the development of strategies for labeling such molecules, particularly RNAs, this may become an important component in conformational analysis. For DNA, labeling is less accessible, but sufficient quantities of unlabeled material are readily available for measuring these couplings at natural abundance. We chose several DNA systems to explore the usefulness of heteronuclear couplings in addressing the sugar conformation and the glycosidic torsion angle. Intensities of cross peaks in long-range HMQC experiments can be related to the couplings. Crosspeaks involving H1{prime} and C1{prime} atoms have been emphasized because of the superior shift dispersion at these positions between sugar protons and carbon atoms. Results will be shown for the self-complementary Dickerson duplex dodecamer sequence d(CGCGAATTCGCG) and for d(GGTCGG), which dimerizes to form a G-tetrad structure incorporating both syn and anti base orientations. The couplings provide a clear discrimination between presence of C3{prime}-endo and C2{prime}-endo conformations of the sugars and syn and anti bases arrangements.

Detailed {sup 1}H and {sup 13}C NMR spectral data assignment for two dihydrobenzofuran neolignans

Energy Technology Data Exchange (ETDEWEB)

Medeiros, Talita C.T.; Dias, Herbert J.; Crotti, Antônio E.M., E-mail: millercrotti@ffclrp.usp.br [Universidade de São Paulo (USP), Ribeirão Preto, SP (Brazil). Faculdade de Filosofia, Ciências e Letras. Departamento de Química

2016-07-01

In this work we present a complete proton ({sup 1}H) and carbon 13 ({sup 13}C) nuclear magnetic resonance (NMR) spectral analysis of two synthetic dihydrofuran neolignans (±)-trans-dehydrodicoumarate dimethyl ester and (±)-trans-dehydrodiferulate dimethyl ester. Unequivocal assignments were achieved by 1 H NMR, proton decoupled {sup 13}C ({sup 13}C{"1H}) NMR spectra, gradient-selected correlation spectroscopy (gCOSY), J-resolved, gradient-selected heteronuclear multiple quantum coherence (gHMQC), gradient-selected heteronuclear multiple bond coherence (gHMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. All hydrogen coupling constants were measured, clarifying all the hydrogen signals multiplicities. Computational methods were also used to simulate the {sup 1}H and {sup 13}C chemical shifts and showed good agreement with the trans configuration of the substituents at C{sub 7} and C{sub 8}. (author)

A general assignment method for oriented sample (OS) solid-state NMR of proteins based on the correlation of resonances through heteronuclear dipolar couplings in samples aligned parallel and perpendicular to the magnetic field.

Science.gov (United States)

Lu, George J; Son, Woo Sung; Opella, Stanley J

2011-04-01

A general method for assigning oriented sample (OS) solid-state NMR spectra of proteins is demonstrated. In principle, this method requires only a single sample of a uniformly ¹⁵N-labeled membrane protein in magnetically aligned bilayers, and a previously assigned isotropic chemical shift spectrum obtained either from solution NMR on micelle or isotropic bicelle samples or from magic angle spinning (MAS) solid-state NMR on unoriented proteoliposomes. The sequential isotropic resonance assignments are transferred to the OS solid-state NMR spectra of aligned samples by correlating signals from the same residue observed in protein-containing bilayers aligned with their normals parallel and perpendicular to the magnetic field. The underlying principle is that the resonances from the same residue have heteronuclear dipolar couplings that differ by exactly a factor of two between parallel and perpendicular alignments. The method is demonstrated on the membrane-bound form of Pf1 coat protein in phospholipid bilayers, whose assignments have been previously made using an earlier generation of methods that relied on the preparation of many selectively labeled (by residue type) samples. The new method provides the correct resonance assignments using only a single uniformly ¹⁵N-labeled sample, two solid-state NMR spectra, and a previously assigned isotropic spectrum. Significantly, this approach is equally applicable to residues in alpha helices, beta sheets, loops, and any other elements of tertiary structure. Moreover, the strategy bridges between OS solid-state NMR of aligned samples and solution NMR or MAS solid-state NMR of unoriented samples. In combination with the development of complementary experimental methods, it provides a step towards unifying these apparently different NMR approaches. Copyright © 2011 Elsevier Inc. All rights reserved.

Two-dimensional NMR spectroscopy. Applications for chemists and biochemists

International Nuclear Information System (INIS)

Croasmun, W.R.; Carlson, R.M.K.

1987-01-01

Two-dimensional nuclear magnetic resonance spectroscopy (2-D NMR) has become a very powerful class of experiments (in the hands of an adept scientist) with broad adaptability to new situations. It is the product of a happy marriage between modern pulse FT-NMR technology, with its large memory and high-speed computers, and the physicists and chemists who love to manipulate spin systems. Basic 2-D experiments are now a standard capability of modern NMR spectrometers, and this timely book intends to make 2-D NMR users of those who are familiar with normal 1-D NMR. The 2-D NMR goal is correlation of the lines of the observed NMR spectrum with other properties of the system. This book deals with applications to high-resolution spectrum analysis, utilizing either coupling between the NMR-active nuclei or chemical exchange to perform the correlation. The coupling can be scalar (through bonds) or direct through space (within 5 A). The coupling may be homonuclear (between like nuclei) or heteronuclear

Adiabatic fast passage application in solid state NMR study of cross relaxation and molecular dynamics in heteronuclear systems.

Science.gov (United States)

Baranowski, M; Woźniak-Braszak, A; Jurga, K

2016-01-01

The paper presents the benefits of using fast adiabatic passage for the study of molecular dynamics in the solid state heteronuclear systems in the laboratory frame. A homemade pulse spectrometer operating at the frequency of 30.2MHz and 28.411MHz for protons and fluorines, respectively, has been enhanced with microcontroller direct digital synthesizer DDS controller [1-4]. This work briefly describes how to construct a low-cost and easy-to-assemble adiabatic extension set for homemade and commercial spectrometers based on recently very popular Arduino shields. The described set was designed for fast adiabatic generation. Timing and synchronization problems are discussed. The cross-relaxation experiments with different initial states of the two spin systems have been performed. Contrary to our previous work [5] where the steady-state NOE experiments were conducted now proton spins (1)H are polarized in the magnetic field B0 while fluorine spins (19)F are perturbed by selective saturation for a short time and then the system is allowed to evolve for a period in the absence of a saturating field. The adiabatic passage application leads to a reversal of magnetization of fluorine spins and increases the amplitude of the signal. Copyright © 2015 Elsevier Inc. All rights reserved.

Heteronuclear Long-Range Correlation

DEFF Research Database (Denmark)

Sørensen, Ole W.

The lecture will cover heteronuclear long-range correlation techniques like HMBC, H2BC, and HAT HMBC with the emphasis on determining the number of covalent bonds between two spins being correlated. H2BC and HMBC spectra are quite complementary as a peak can be strong in one of the two spectra...

Dante-Z sequence as selective impulsion in high field mono and multidimensional NMR. Application to the study of proteins, peptides and their interactions

International Nuclear Information System (INIS)

Roumestand, C.; Toma, F.

1992-01-01

DANTE-Z is a simple and efficient way for NMR spectral selection. We present here different applications of DANTE-Z in high-resolution NMR of peptides and proteins. We have been using proton selective excitation by DANTE-Z to perform 1D-correlated (homo- or heteronuclear) experiments corresponding to one line of either 2D or 3D experiments. Following the same scheme, we could also edit planes of 3D experiments by concatenating 1D-correlated experiments with conventional 2D experiments. In the heteronuclear case (i.e. 1 H, 31 P), we could also edit planes of a 4D experiment by the simultaneous selection of 1 H and the X nucleus. Owing to the favourable excitation profile of DANTE-Z, we used it successfully for topological excitations (spectral width from 150 Hz up to 1500 Hz) in 'semi-soft'-2D experiments and 'soft'-2D experiment. These applications are illustrated by the results obtained at 600 MHz on a protein and a phosphonamide peptide

Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hou, Guangjin, E-mail: hou@udel.edu, E-mail: tpolenov@udel.edu; Lu, Xingyu, E-mail: luxingyu@udel.edu, E-mail: lexvega@comcast.net; Vega, Alexander J., E-mail: luxingyu@udel.edu, E-mail: lexvega@comcast.net; Polenova, Tatyana, E-mail: hou@udel.edu, E-mail: tpolenov@udel.edu [Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, Pennsylvania 15261 (United States)

2014-09-14

We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear {sup 1}H-X (X = {sup 13}C, {sup 15}N, {sup 31}P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the {sup 1}H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the {sup 1}H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from {sup 1}H chemical shift anisotropy, while keeping the {sup 1}H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [{sup 15}N]-N-acetyl-valine and [U-{sup 13}C,{sup 15}N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate {sup 1}H-{sup 15}N dipolar couplings in the context of 3D experiments is presented on U-{sup 13}C,{sup 15}N-enriched dynein light chain protein LC8.

NMR-Assisted Structure Elucidation of an Anticancer Steroid-β-Enaminone Derivative

Directory of Open Access Journals (Sweden)

Donald Poirier

2017-11-01

Full Text Available The fortuitous modification of a quinoline-proline-piperazine side chain linked to a steroid in the presence of lithium (trimethylsilyl acetylide has generated an unknown product that is more active than its precursor. After having characterized two β-enaminones (two-carbon homologation compounds that were generated from a simplified model side chain, we have identified the unknown product as being the β-enaminone steroid derivative 1. NMR analysis, especially two-dimensional (2D experiments (correlation spectroscopy (COSY, NOE spectroscopy (NOESY, heteronuclear single-quantum correlation (HSQC and heteronuclear multiple-bond correlation (HMBC provided crucial information that was found essential in the characterization of enaminone 1. We also proposed a mechanism to rationalize the formation of this biologically active compound.

Structures of larger proteins in solution: Three- and four-dimensional heteronuclear NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Gronenborn, A.M.; Clore, G.M. [National Institutes of Health, Bethesda, MD (United States)

1994-12-01

Complete understanding of a protein`s function and mechanism of action can only be achieved with a knowledge of its three-dimensional structure at atomic resolution. At present, there are two methods available for determining such structures. The first method, which has been established for many years, is x-ray diffraction of protein single crystals. The second method has blossomed only in the last 5 years and is based on the application of nuclear magnetic resonance (NMR) spectroscopy to proteins in solution. This review paper describes three- and four-dimensional NMR methods applied to protein structure determination and was adapted from Clore and Gronenborn. The review focuses on the underlying principals and practice of multidimensional NMR and the structural information obtained.

Natural abundant solid state NMR studies in designed tripeptides for differentiation of multiple conformers.

Science.gov (United States)

Jayanthi, S; Chatterjee, Bhaswati; Raghothama, S

2009-10-01

Solid state NMR (SSNMR) experiments on heteronuclei in natural abundance are described for three synthetically designed tripeptides Piv-(L)Pro-(L)Pro-(L)Phe-OMe (1), Piv-(D)Pro-(L)Pro-(L)Phe-OMe (2), and Piv-(D)Pro-(L)Pro-(L)Phe-NHMe (3). These peptides exist in different conformation as shown by solution state NMR and single crystal X-ray analysis (Chatterjee et al., Chem Eur J 2008, 14, 6192). In this study, SSNMR has been used to probe the conformations of these peptides in their powder form. The (13)C spectrum of peptide (1) showed doubling of resonances corresponding to cis/cis form, unlike in solution where the similar doubling is attributed to cis/trans form. This has been confirmed by the chemical shift differences of C(beta) and C(gamma) carbon of Proline in peptide (1) both in solution and SSNMR. Peptide (2) and (3) provided single set of resonances which represented all trans form across the di-Proline segment. The results are in agreement with the X-ray analysis. Solid state (15)N resonances, especially from Proline residues provided additional information, which is normally not observable in solution state NMR. (1)H chemical shifts are also obtained from a two-dimensional heteronuclear correlation experiment between (1)H--(13)C. The results confirm the utility of NMR as a useful tool for identifying different conformers in peptides in the solid state. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 851-860, 2009.

An improved ultrafast 2D NMR experiment: Towards atom-resolved real-time studies of protein kinetics at multi-Hz rates

International Nuclear Information System (INIS)

Gal, Maayan; Kern, Thomas; Schanda, Paul; Frydman, Lucio; Brutscher, Bernhard

2009-01-01

Multidimensional NMR spectroscopy is a well-established technique for the characterization of structure and fast-time-scale dynamics of highly populated ground states of biological macromolecules. The investigation of short-lived excited states that are important for molecular folding, misfolding and function, however, remains a challenge for modern biomolecular NMR techniques. Off-equilibrium real-time kinetic NMR methods allow direct observation of conformational or chemical changes by following peak positions and intensities in a series of spectra recorded during a kinetic event. Because standard multidimensional NMR methods required to yield sufficient atom-resolution are intrinsically time-consuming, many interesting phenomena are excluded from real-time NMR analysis. Recently, spatially encoded ultrafast 2D NMR techniques have been proposed that allow one to acquire a 2D NMR experiment within a single transient. In addition, when combined with the SOFAST technique, such ultrafast experiments can be repeated at high rates. One of the problems detected for such ultrafast protein NMR experiments is related to the heteronuclear decoupling during detection with interferences between the pulses and the oscillatory magnetic field gradients arising in this scheme. Here we present a method for improved ultrafast data acquisition yielding higher signal to noise and sharper lines in single-scan 2D NMR spectra. In combination with a fast-mixing device, the recording of 1 H- 15 N correlation spectra with repetition rates of up to a few Hertz becomes feasible, enabling real-time studies of protein kinetics occurring on time scales down to a few seconds

Non-Uniform Sampling and J-UNIO Automation for Efficient Protein NMR Structure Determination.

Science.gov (United States)

Didenko, Tatiana; Proudfoot, Andrew; Dutta, Samit Kumar; Serrano, Pedro; Wüthrich, Kurt

2015-08-24

High-resolution structure determination of small proteins in solution is one of the big assets of NMR spectroscopy in structural biology. Improvements in the efficiency of NMR structure determination by advances in NMR experiments and automation of data handling therefore attracts continued interest. Here, non-uniform sampling (NUS) of 3D heteronuclear-resolved [(1)H,(1)H]-NOESY data yielded two- to three-fold savings of instrument time for structure determinations of soluble proteins. With the 152-residue protein NP_372339.1 from Staphylococcus aureus and the 71-residue protein NP_346341.1 from Streptococcus pneumonia we show that high-quality structures can be obtained with NUS NMR data, which are equally well amenable to robust automated analysis as the corresponding uniformly sampled data. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular docking and NMR binding studies to identify novel inhibitors of human phosphomevalonate kinase

Energy Technology Data Exchange (ETDEWEB)

Boonsri, Pornthip [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States); Department of Chemistry, NANOTEC Center of Nanotechnology, National Nanotechnology Center, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Neumann, Terrence S.; Olson, Andrew L.; Cai, Sheng [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States); Herdendorf, Timothy J.; Miziorko, Henry M. [Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Hannongbua, Supa [Department of Chemistry, NANOTEC Center of Nanotechnology, National Nanotechnology Center, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Sem, Daniel S., E-mail: daniel.sem@cuw.edu [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States)

2013-01-04

Highlights: Black-Right-Pointing-Pointer Natural and synthetic inhibitors of human phosphomevalonate kinase identified. Black-Right-Pointing-Pointer Virtual screening yielded a hit rate of 15%, with inhibitor K{sub d}'s of 10-60 {mu}M. Black-Right-Pointing-Pointer NMR studies indicate significant protein conformational changes upon binding. -- Abstract: Phosphomevalonate kinase (PMK) phosphorylates mevalonate-5-phosphate (M5P) in the mevalonate pathway, which is the sole source of isoprenoids and steroids in humans. We have identified new PMK inhibitors with virtual screening, using autodock. Promising hits were verified and their affinity measured using NMR-based {sup 1}H-{sup 15}N heteronuclear single quantum coherence (HSQC) chemical shift perturbation and fluorescence titrations. Chemical shift changes were monitored, plotted, and fitted to obtain dissociation constants (K{sub d}). Tight binding compounds with K{sub d}'s ranging from 6-60 {mu}M were identified. These compounds tended to have significant polarity and negative charge, similar to the natural substrates (M5P and ATP). HSQC cross peak changes suggest that binding induces a global conformational change, such as domain closure. Compounds identified in this study serve as chemical genetic probes of human PMK, to explore pharmacology of the mevalonate pathway, as well as starting points for further drug development.

Immobilization of (dd)heteronuclear hexacyanoferrates(II) in a gelatin matrix

International Nuclear Information System (INIS)

Mikhajlov, O.V.

2008-01-01

Data pertinent to potentiality of preparing salts of (dd)heteronuclear hexacyanoferrates(II) with(M 1 ) II and (M 2 ) II (M 1 , M 2 = Mn, Co, Ni, Cu, Zn, Cd) as a result of contact between M 1 2 [Fe(CN) 6 ] immobilized in a gelatin matrix and aqueous solutions of metal chlorides have been systematized and summarized. The decisive role of the gelatin matrix, performing the function of an organizing system in formation of (dd)heteronuclear hexacyanoferrates(II) of metals, has been pointed out [ru

Phase behaviour of heteronuclear dimers in three-dimensional systems-a Monte Carlo study

International Nuclear Information System (INIS)

Rzysko, W; Binder, K

2008-01-01

Monte Carlo simulation in the grand canonical ensemble, the histogram reweighting technique and finite size scaling are used to study the phase behaviour of dimers in three-dimensional systems. A single molecule is composed of two segments A and B, and the bond between them cannot be broken. The phase diagrams have been estimated for a set of model systems. Different structures formed by heteronuclear dimers have been found. The results show a great variety of vapour-liquid coexistence behaviour depending on the strength of the interactions between segments

Two dimensional NMR of liquids and oriented molecules

International Nuclear Information System (INIS)

Gochin, M.

1987-02-01

Chapter 1 discusses the quantum mechanical formalism used for describing the interaction between magnetic dipoles that dictates the appearance of a spectrum. The NMR characteristics of liquids and liquid crystals are stressed. Chapter 2 reviews the theory of multiple quantum and two dimensional NMR. Properties of typical spectra and phase cycling procedures are discussed. Chapter 3 describes a specific application of heteronuclear double quantum coherence to the removal of inhomogeneous broadening in liquids. Pulse sequences have been devised which cancel out any contribution from this inhomogeneity to the final spectrum. An interpretation of various pulse sequences for the case of 13 C and 1 H is given, together with methods of spectral editing by removal or retention of the homo- or heteronuclear J coupling. The technique is applied to a demonstration of high resolution in both frequency and spatial dimensions with a surface coil. In Chapter 4, multiple quantum filtered 2-D spectroscopy is demonstrated as an effective means of studying randomly deuterated molecules dissolved in a nematic liquid crystal. Magnitudes of dipole coupling constants have been determined for benzene and hexane, and their signs and assignments found from high order multiple quantum spectra. For the first time, a realistic impression of the conformation of hexane can be estimated from these results. Chapter 5 is a technical description of the MDB DCHIB-DR11W parallel interface which has been set up to transfer data between the Data General Nova 820 minicomputer, interfaced to the 360 MHz spectrometer, and the Vax 11/730. It covers operation of the boards, physical specifications and installation, and programs for testing and running the interface

Two dimensional NMR of liquids and oriented molecules

Energy Technology Data Exchange (ETDEWEB)

Gochin, M.

1987-02-01

Chapter 1 discusses the quantum mechanical formalism used for describing the interaction between magnetic dipoles that dictates the appearance of a spectrum. The NMR characteristics of liquids and liquid crystals are stressed. Chapter 2 reviews the theory of multiple quantum and two dimensional NMR. Properties of typical spectra and phase cycling procedures are discussed. Chapter 3 describes a specific application of heteronuclear double quantum coherence to the removal of inhomogeneous broadening in liquids. Pulse sequences have been devised which cancel out any contribution from this inhomogeneity to the final spectrum. An interpretation of various pulse sequences for the case of /sup 13/C and /sup 1/H is given, together with methods of spectral editing by removal or retention of the homo- or heteronuclear J coupling. The technique is applied to a demonstration of high resolution in both frequency and spatial dimensions with a surface coil. In Chapter 4, multiple quantum filtered 2-D spectroscopy is demonstrated as an effective means of studying randomly deuterated molecules dissolved in a nematic liquid crystal. Magnitudes of dipole coupling constants have been determined for benzene and hexane, and their signs and assignments found from high order multiple quantum spectra. For the first time, a realistic impression of the conformation of hexane can be estimated from these results. Chapter 5 is a technical description of the MDB DCHIB-DR11W parallel interface which has been set up to transfer data between the Data General Nova 820 minicomputer, interfaced to the 360 MHz spectrometer, and the Vax 11/730. It covers operation of the boards, physical specifications and installation, and programs for testing and running the interface.

NMR studies of the fate of adenine nucleotides in glucose-starved erythrocytes

International Nuclear Information System (INIS)

Bubb, W.A.; Mulquiney, P.J.; Kuchel, P.W.; Rohwer, J.; De Atauri, P.

2002-01-01

Full text: As a consequence of many refinements during the past 30 years, we now have a detailed understanding of the glycolytic pathway in human erythrocytes. By comparison, and notwithstanding their central importance to four key steps in erythrocyte glycolysis, our knowledge of the catabolism of adenine nucleotides remains relatively limited. In particular, the mechanism for the degradation of AMP, whose concentration rises under conditions of oxidative stress or glucose deprivation, remains poorly understood, AMP degradation may proceed via two possible pathways which converge in the production of inosine. Analysis of the key intermediates for the respective pathways, adenosine and AMP, as well as determination of end products is not straightforward. High-resolution NMR spectroscopy affords a potentially simple analytical solution to this problem but is complicated by spectral overlap and the sensitivity of key resonances to variations in pH and the concentrations of cations such as Mg 2+ . We describe a multinuclear NMR approach towards characterising the intermediates and end-products of adenine nucleotide metabolism in glucose-starved human erythrocytes. Assignments based on homo- and heteronuclear correlation experiments for both 13 C and 31 P are presented

Collisional properties of weakly bound heteronuclear dimers

NARCIS (Netherlands)

Marcelis, B.; Kokkelmans, S.J.J.M.F.; Shlyapnikov, G.V.; Petrov, D.S.

2008-01-01

We consider collisional properties of weakly bound heteronuclear molecules (dimers) formed in a two-species mixture of atoms with a large mass difference. We focus on dimers containing light fermionic atoms as they manifest collisional stability due to an effective dimer-dimer repulsion originating

Synthesis and investigation of new heteronuclear [Zn-La] coordination compounds based on unsaturated lanthanum complex with N,N'-tetraethyl-N''-trichloacetylphosphortriamide

International Nuclear Information System (INIS)

Amyirkhanov, O.V.; Sliva, T.Yu.; Moroz, O.V.; Trush, Je.A.; Frits'kij, Yi.O.

2011-01-01

New heteronuclear [Zn-La] coordination compounds, perspective luminescent materials, with general formulas [Zn(Ve)La(X) 2 (Ac)] ({Zn-La;Ve;X}) and [Zn(Vp)La(X) 2 (Ac)] ({Zn-La;Vp;X}) have been synthesized HX=CCl 3 C(O)NHP(O)[N(C 2 H 5 ) 2 ] 2 - N,N'-tetraethyl-N''-trichloracetylphosphortriamide, H 2 Ve and H 2 Vp are products of the condensation of 1,2-diaminoethane and 1,3-diaminopropane with o-vanillin, respectively). The composition of [Zn-La] complexes has been determined, and the coordination mode of a phosphorylated ligand has been suggested by element analysis, IR- and 1 H, 31 P NMR-spectroscopy.

Na/Ca Intermixing around Silicate and Phosphate Groups in Bioactive Phosphosilicate Glasses Revealed by Heteronuclear Solid-State NMR and Molecular Dynamics Simulations.

Science.gov (United States)

Mathew, Renny; Stevensson, Baltzar; Edén, Mattias

2015-04-30

We characterize the intermixing of network-modifying Na(+)/Ca(2+) ions around the silicate (QSi(n)) and phosphate (QP(n)) tetrahedra in a series of 16 Na2O–CaO–SiO2–P2O5 glasses, whose P content and silicate network connectivity were varied independently. The set includes both bioactive and bioinactive compositions and also encompasses two soda-lime-silicate members devoid of P, as well as two CaO–SiO2 glasses and one Na2O–SiO2–P2O5 glass. The various Si/P↔Na/Ca contacts were probed by molecular dynamics (MD) simulations together with heteronuclear magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) experimentation utilizing (23)Na{(31)P} and (23)Na{(29)Si} REDOR, as well as (31)P{ (23)Na} and (29)Si{(23)Na} REAPDOR. We introduce an approach for quantifying the extent of Na(+)/Ca(2+) ordering around a given QP(n) or QSi(n) group, encoded by the preference factor 0⩽ PM ⩽ 1 conveying the relative weights of a random cation intermixing (PM = 0) and complete preference/ordering (PM = 1) for one of the species M, which represents either Na(+) or Ca(2+). The MD-derived preference factors reveal phosphate and silicate species surrounded by Na(+)/Ca(2+) ions intermixed nearly randomly (PM ≲ 0.15), except for the QSi(4) and QSi(1) groups, which manifest more significant cation ordering with preference for Na+ and Ca2+, respectively. The overall weak preferences are essentially independent of the Si and P contents of the glass, whereas PM primarily correlates with the total amount of network modifiers: as the latter is increased, the Na/Ca distribution around the {QP(0), QSi(1), QSi(2)} groups with preference for Ca2(+ )tend to randomize (i.e., PCa decreases), while the PNa-values grow slightly for the {QP(1), QSi(3), QSi(4)} species already preferring coordination of Na. The set of experimental preference factors {PCa} for the orthophosphate (QP(0)) groups extracted from (31)P{(23)Na} REAPDOR NMR-derived M2(P–Na) dipolar second moments agrees

Selective {sup 2}H and {sup 13}C labeling in NMR analysis of solution protein structure and dynamics

Energy Technology Data Exchange (ETDEWEB)

LeMaster, D.M. [Northwestern Univ., Evanston, IL (United States)

1994-12-01

Preparation of samples bearing combined isotope enrichment patterns has played a central role in the recent advances in NMR analysis of proteins in solution. In particular, uniform {sup 13}C, {sup 15}N enrichment has made it possible to apply heteronuclear multidimensional correlation experiments for the mainchain assignments of proteins larger than 30 KDa. In contrast, selective labeling approaches can offer advantages in terms of the directedness of the information provided, such as chirality and residue type assignments, as well as through enhancements in resolution and sensitivity that result from editing the spectral complexity, the relaxation pathways and the scalar coupling networks. In addition, the combination of selective {sup 13}C and {sup 2}H enrichment can greatly facilitate the determination of heteronuclear relaxation behavior.

2D 1H -13C Heteronuclear Shift Correlation Of 2a - Hydroxy Aiantolactone From Pulicaria Undulata C.A. Mey

Directory of Open Access Journals (Sweden)

A. Rustaiyan

1992-07-01

Full Text Available We have reported recently the isolation and characterization of several sesquiterpene lactones from Pulicaria undulata (1."nThe lactones were isolated from an Et20 - Petrol (1:3 fraction by different chromatographic techniques including HPLC (RP 8, MeOH - H2O, 13:7."nIn this way three eudesmanolides 1 - 3, a guaianolide 4, a nor -guaianolide 5, as well as the pseudoguaianolide 6 and the xanthanolide 7 were isolated. One of the eudesmanolides (2a - hydroxy aiantolactone, 1, was present as the main component."nSuch lactones being known as biologically active substances, we have decided to describe for the first time a detailed interpretation of proton, 1H -NMR, 13C - NMR and 2D lH -13C - heteronuclear shift correlation spectra of 2a - hydroxy aiantolactone. The stereochemistry of C - 2 , C - 7 and C - 8 was determined by the NOESY experiments, H - 7 and H - 8 are in the a configuration and H - 2 is in the b configuration.

Two dimensional NMR studies of polysaccharides

International Nuclear Information System (INIS)

Byrd, R.A.; Egan, W.; Summers, M.F.

1987-01-01

Polysaccharides are very important components in the immune response system. Capsular polysaccharides and lipopolysaccharides occupy cell surface sites of bacteria, play key roles in recognition and some have been used to develop vaccines. Consequently, the ability to determine chemical structures of these systems is vital to an understanding of their immunogenic action. The authors have been utilizing recently developed two-dimensional homonuclear and heteronuclear correlation spectroscopy for unambiguous assignment and structure determination of a number of polysaccharides. In particular, the 1 H-detected heteronuclear correlation experiments are essential to the rapid and sensitive determination of these structures. Linkage sites are determined by independent polarization transfer experiments and multiple quantum correlation experiments. These methods permit the complete structure determination on very small amounts of the polysaccharides. They present the results of a number of structural determinations and discuss the limits of these experiments in terms of their applications to polysaccharides

Pulsed zero field NMR of solids and liquid crystals

International Nuclear Information System (INIS)

Thayer, A.M.

1987-02-01

This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs

Pumping vortex into a Bose-Einstein condensate of heteronuclear molecules

International Nuclear Information System (INIS)

Xu, Z F; Wang, R Q; You, L

2009-01-01

Heteronuclear molecules have attracted wide attention due to their permanent electric dipole moments. Analogous to atoms with magnetic dipoles, the existence of nonzero electric dipoles significantly enhances the possibilities and mechanisms for the control and design of quantum degenerate molecule systems with electric (E) fields. This work proposes a vortex creation mechanism inside a condensate of heteronuclear molecules through the adiabatic flipping of the axial bias of an analogous E-field Ioffe-Pritchard trap (IPT), extending the original protocol of Isoshima et al (2000 Phys. Rev. A 61 063610) for an atomic spinor condensate inside a magnetic (B)-field IPT. We provide both analytic proof and numerical simulations to illustrate the high fidelity operation of this vortex pump protocol. We hope our work provides stimulating experimental possibilities for active investigations in quantum degenerate molecule systems.

Heteronuclear 2D (1H-13C) MAS NMR Resolves the Electronic Structure of Coordinated Histidines in Light-Harvesting Complex II: Assessment of Charge Transfer and Electronic Delocalization Effect

International Nuclear Information System (INIS)

Matysik, Joerg; Boer, Ido de; Gast, Peter; Gorkom, Hans J. van; Groot, Huub J.M. de

2004-01-01

In a recent MAS NMR study, two types of histidine residues in the light-harvesting complex II (LH2) of Rhodopseudomonas acidophila were resolved: Type 1 (neutral) and Type 2 (positively charged) (Alia et al. J. Am. Chem. Soc.). The isotropic 13 C shifts of histidines coordinating to B850 BChl a are similar to fully positively charged histidine, while the 15 N shift anisotropy shows a predominantly neutral character. In addition the possibility that the ring currents are quenched by overlap in the superstructure of the complete ring of 18 B850 molecules in the LH2 complex could not be excluded. In the present work, by using two-dimensional heteronuclear ( 1 H- 13 C) dipolar correlation spectroscopy with phase-modulated Lee-Goldburg homonuclear 1 H decoupling applied during the t 1 period, a clear and unambiguous assignment of the protons of histidine interacting with the magnesium of a BChl a molecule is obtained and a significant ring current effect from B850 on the coordinating histidine is resolved. Using the ring current shift on 1 H, we refine the 13 C chemical shift assignment of the coordinating histidine and clearly distinguish the electronic structure of coordinating histidines from that of fully positively charged histidine. The DFT calculations corroborate that the coordinating histidines carry ∼0.2 electronic equivalent of positive charge in LH2. In addition, the data indicate that the ground state electronic structures of individual BChl a/His complexes is largely independent of supermolecular π interactions in the assembly of 18 B850 ring in LH2

Fragment based drug discovery: practical implementation based on ¹⁹F NMR spectroscopy.

Science.gov (United States)

Jordan, John B; Poppe, Leszek; Xia, Xiaoyang; Cheng, Alan C; Sun, Yax; Michelsen, Klaus; Eastwood, Heather; Schnier, Paul D; Nixey, Thomas; Zhong, Wenge

2012-01-26

Fragment based drug discovery (FBDD) is a widely used tool for discovering novel therapeutics. NMR is a powerful means for implementing FBDD, and several approaches have been proposed utilizing (1)H-(15)N heteronuclear single quantum coherence (HSQC) as well as one-dimensional (1)H and (19)F NMR to screen compound mixtures against a target of interest. While proton-based NMR methods of fragment screening (FBS) have been well documented and are widely used, the use of (19)F detection in FBS has been only recently introduced (Vulpetti et al. J. Am. Chem. Soc.2009, 131 (36), 12949-12959) with the aim of targeting "fluorophilic" sites in proteins. Here, we demonstrate a more general use of (19)F NMR-based fragment screening in several areas: as a key tool for rapid and sensitive detection of fragment hits, as a method for the rapid development of structure-activity relationship (SAR) on the hit-to-lead path using in-house libraries and/or commercially available compounds, and as a quick and efficient means of assessing target druggability.

Determination of relative configurations and conformations of oxindole alkaloids from Uncaria guianensis by NMR; Determinacao por RMN das configuracoes relativas e conformacoes de alcaloides oxindolicos isolados de Uncaria guianensis

Energy Technology Data Exchange (ETDEWEB)

Carbonezi, Carlos Alberto; Hamerski, Lidilhone; Flausino Junior, Otavio Aparecido; Furlan, Maysa; Bolzani, Vanderlan da Silva [UNESP, Araraquara, SP (Brazil). Inst. de Quimica]. E-mail: bolzaniv@iq.unesp.br; Young, Maria Claudia Marx [Instituto de Botanica, Sao Paulo, SP (Brazil). Secao de Fisiologia e Bioquimica de Plantas

2004-12-01

Phytochemical studies with leaves of Uncaria guianensis resulted in the isolation of the oxindole alkaloids isomitraphylline (1), 3-isoajmalicine (2) mitraphylline (3), and isomitraphylinic acid (4). Structural assignments of these alkaloids, including relative configurations and conformations, were performed through spectral data and physical properties. 1D and 2D homonuclear and heteronuclear NMR spectroscopy was a valuable tool for the establishment of the relative stereochemistry of those compounds. (author)

APSY-NMR for protein backbone assignment in high-throughput structural biology

Energy Technology Data Exchange (ETDEWEB)

Dutta, Samit Kumar; Serrano, Pedro; Proudfoot, Andrew; Geralt, Michael [The Scripps Research Institute, Department of Integrative Structural and Computational Biology (United States); Pedrini, Bill [Paul Scherrer Institute (PSI), SwissFEL Project (Switzerland); Herrmann, Torsten [Université de Lyon, Institut des Sciences Analytiques, Centre de RMN à Très Hauts Champs, UMR 5280 CNRS, ENS Lyon, UCB Lyon 1 (France); Wüthrich, Kurt, E-mail: wuthrich@scripps.edu [The Scripps Research Institute, Department of Integrative Structural and Computational Biology (United States)

2015-01-15

A standard set of three APSY-NMR experiments has been used in daily practice to obtain polypeptide backbone NMR assignments in globular proteins with sizes up to about 150 residues, which had been identified as targets for structure determination by the Joint Center for Structural Genomics (JCSG) under the auspices of the Protein Structure Initiative (PSI). In a representative sample of 30 proteins, initial fully automated data analysis with the software UNIO-MATCH-2014 yielded complete or partial assignments for over 90 % of the residues. For most proteins the APSY data acquisition was completed in less than 30 h. The results of the automated procedure provided a basis for efficient interactive validation and extension to near-completion of the assignments by reference to the same 3D heteronuclear-resolved [{sup 1}H,{sup 1}H]-NOESY spectra that were subsequently used for the collection of conformational constraints. High-quality structures were obtained for all 30 proteins, using the J-UNIO protocol, which includes extensive automation of NMR structure determination.

J-UNIO protocol used for NMR structure determination of the 206-residue protein NP-346487.1 from Streptococcus pneumoniae TIGR4

Energy Technology Data Exchange (ETDEWEB)

Jaudzems, Kristaps [Latvian Institute of Organic Synthesis (Latvia); Pedrini, Bill [Paul Scherrer Institute (PSI), SwissFEL Project (Switzerland); Geralt, Michael; Serrano, Pedro; Wüthrich, Kurt, E-mail: wuthrich@scripps.edu [The Scripps Research Institute, Department of Integrative Structural and Computational Biology (United States)

2015-01-15

The NMR structure of the 206-residue protein NP-346487.1 was determined with the J-UNIO protocol, which includes extensive automation of the structure determination. With input from three APSY-NMR experiments, UNIO-MATCH automatically yielded 77 % of the backbone assignments, which were interactively validated and extended to 97 %. With an input of the near-complete backbone assignments and three 3D heteronuclear-resolved [{sup 1}H,{sup 1}H]-NOESY spectra, automated side chain assignment with UNIO-ATNOS/ASCAN resulted in 77 % of the expected assignments, which was extended interactively to about 90 %. Automated NOE assignment and structure calculation with UNIO-ATNOS/CANDID in combination with CYANA was used for the structure determination of this two-domain protein. The individual domains in the NMR structure coincide closely with the crystal structure, and the NMR studies further imply that the two domains undergo restricted hinge motions relative to each other in solution. NP-346487.1 is so far the largest polypeptide chain to which the J-UNIO structure determination protocol has successfully been applied.

TG/DTG, FT-ICR Mass Spectrometry, and NMR Spectroscopy Study of Heavy Fuel Oil

KAUST Repository

Elbaz, Ayman M.

2015-11-12

There is an increasing interest in the comprehensive study of heavy fuel oil (HFO) due to its growing use in furnaces, boilers, marines, and recently in gas turbines. In this work, the thermal combustion characteristics and chemical composition of HFO were investigated using a range of techniques. Thermogravimetric analysis (TGA) was conducted to study the nonisothermal HFO combustion behavior. Chemical characterization of HFO was accomplished using various standard methods in addition to direct infusion atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (APCI-FTICR MS), high resolution 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear multiple bond correlation (HMBC) spectroscopy. By analyzing thermogravimetry and differential thermogravimetry (TG/DTG) results, three different reaction regions were identified in the combustion of HFO with air, specifically, low temperature oxidation region (LTO), fuel deposition (FD), and high temperature oxidation (HTO) region. At the high end of the LTO region, a mass transfer resistance (skin effect) was evident. Kinetic analysis in LTO and HTO regions was conducted using two different kinetic models to calculate the apparent activation energy. In both models, HTO activation energies are higher than those for LTO. The FT-ICR MS technique resolved thousands of aromatic and sulfur containing compounds in the HFO sample and provided compositional details for individual molecules of three major class species. The major classes of compounds included species with one sulfur atom (S1), with two sulfur atoms (S2), and purely hydrocarbons (HC). The DBE (double bond equivalent) abundance plots established for S1 and HC provided additional information on their distributions in the HFO sample. The 1H NMR and 13C NMR results revealed that nearly 59% of the 1H nuclei were distributed as paraffinic CH2 and 5% were in aromatic groups. Nearly 21% of 13C nuclei were

Heteronuclear Adiabatic Relaxation Dispersion (HARD) for quantitative analysis of conformational dynamics in proteins.

Science.gov (United States)

Traaseth, Nathaniel J; Chao, Fa-An; Masterson, Larry R; Mangia, Silvia; Garwood, Michael; Michaeli, Shalom; Seelig, Burckhard; Veglia, Gianluigi

2012-06-01

NMR relaxation methods probe biomolecular motions over a wide range of timescales. In particular, the rotating frame spin-lock R(1ρ) and Carr-Purcell-Meiboom-Gill (CPMG) R(2) experiments are commonly used to characterize μs to ms dynamics, which play a critical role in enzyme folding and catalysis. In an effort to complement these approaches, we introduced the Heteronuclear Adiabatic Relaxation Dispersion (HARD) method, where dispersion in rotating frame relaxation rate constants (longitudinal R(1ρ) and transverse R(2ρ)) is created by modulating the shape and duration of adiabatic full passage (AFP) pulses. Previously, we showed the ability of the HARD method to detect chemical exchange dynamics in the fast exchange regime (k(ex)∼10(4)-10(5) s(-1)). In this article, we show the sensitivity of the HARD method to slower exchange processes by measuring R(1ρ) and R(2ρ) relaxation rates for two soluble proteins (ubiquitin and 10C RNA ligase). One advantage of the HARD method is its nominal dependence on the applied radio frequency field, which can be leveraged to modulate the dispersion in the relaxation rate constants. In addition, we also include product operator simulations to define the dynamic range of adiabatic R(1ρ) and R(2ρ) that is valid under all exchange regimes. We conclude from both experimental observations and simulations that this method is complementary to CPMG-based and rotating frame spin-lock R(1ρ) experiments to probe conformational exchange dynamics for biomolecules. Finally, this approach is germane to several NMR-active nuclei, where relaxation rates are frequency-offset independent. Copyright © 2012 Elsevier Inc. All rights reserved.

Resonance assignment for a particularly challenging protein based on systematic unlabeling of amino acids to complement incomplete NMR data sets

International Nuclear Information System (INIS)

Bellstedt, Peter; Seiboth, Thomas; Häfner, Sabine; Kutscha, Henriette; Ramachandran, Ramadurai; Görlach, Matthias

2013-01-01

NMR-based structure determination of a protein requires the assignment of resonances as indispensable first step. Even though heteronuclear through-bond correlation methods are available for that purpose, challenging situations arise in cases where the protein in question only yields samples of limited concentration and/or stability. Here we present a strategy based upon specific individual unlabeling of all 20 standard amino acids to complement standard NMR experiments and to achieve unambiguous backbone assignments for the fast precipitating 23 kDa catalytic domain of human aprataxin of which only incomplete standard NMR data sets could be obtained. Together with the validation of this approach utilizing the protein GB1 as a model, a comprehensive insight into metabolic interconversion ('scrambling”) of NH and CO groups in a standard Escherichia coli expression host is provided

Biological activities of a new compound isolated from the aerial parts ...

African Journals Online (AJOL)

A new compound trivially named vitexcarpan was isolated from the ethyl acetate fraction of Vitex agnus castus. The structure of compound was elucidated with the help of spectroscopic techniques: 13C NMR, 1H NMR, heteronuclear multiple bond correlation (HMBC), heteronuclear multiple quantum coherence (HMQC), ...

Reducing acquisition times in multidimensional NMR with a time-optimized Fourier encoding algorithm

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhiyong [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005 (China); Smith, Pieter E. S.; Frydman, Lucio, E-mail: lucio.frydman@weizmann.ac.il [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

2014-11-21

Speeding up the acquisition of multidimensional nuclear magnetic resonance (NMR) spectra is an important topic in contemporary NMR, with central roles in high-throughput investigations and analyses of marginally stable samples. A variety of fast NMR techniques have been developed, including methods based on non-uniform sampling and Hadamard encoding, that overcome the long sampling times inherent to schemes based on fast-Fourier-transform (FFT) methods. Here, we explore the potential of an alternative fast acquisition method that leverages a priori knowledge, to tailor polychromatic pulses and customized time delays for an efficient Fourier encoding of the indirect domain of an NMR experiment. By porting the encoding of the indirect-domain to the excitation process, this strategy avoids potential artifacts associated with non-uniform sampling schemes and uses a minimum number of scans equal to the number of resonances present in the indirect dimension. An added convenience is afforded by the fact that a usual 2D FFT can be used to process the generated data. Acquisitions of 2D heteronuclear correlation NMR spectra on quinine and on the anti-inflammatory drug isobutyl propionic phenolic acid illustrate the new method's performance. This method can be readily automated to deal with complex samples such as those occurring in metabolomics, in in-cell as well as in in vivo NMR applications, where speed and temporal stability are often primary concerns.

Reducing acquisition times in multidimensional NMR with a time-optimized Fourier encoding algorithm

International Nuclear Information System (INIS)

Zhang, Zhiyong; Smith, Pieter E. S.; Frydman, Lucio

2014-01-01

Speeding up the acquisition of multidimensional nuclear magnetic resonance (NMR) spectra is an important topic in contemporary NMR, with central roles in high-throughput investigations and analyses of marginally stable samples. A variety of fast NMR techniques have been developed, including methods based on non-uniform sampling and Hadamard encoding, that overcome the long sampling times inherent to schemes based on fast-Fourier-transform (FFT) methods. Here, we explore the potential of an alternative fast acquisition method that leverages a priori knowledge, to tailor polychromatic pulses and customized time delays for an efficient Fourier encoding of the indirect domain of an NMR experiment. By porting the encoding of the indirect-domain to the excitation process, this strategy avoids potential artifacts associated with non-uniform sampling schemes and uses a minimum number of scans equal to the number of resonances present in the indirect dimension. An added convenience is afforded by the fact that a usual 2D FFT can be used to process the generated data. Acquisitions of 2D heteronuclear correlation NMR spectra on quinine and on the anti-inflammatory drug isobutyl propionic phenolic acid illustrate the new method's performance. This method can be readily automated to deal with complex samples such as those occurring in metabolomics, in in-cell as well as in in vivo NMR applications, where speed and temporal stability are often primary concerns

Heteronuclear Micro-Helmholtz Coil Facilitates µm-Range Spatial and Sub-Hz Spectral Resolution NMR of nL-Volume Samples on Customisable Microfluidic Chips.

Directory of Open Access Journals (Sweden)

Nils Spengler

Full Text Available We present a completely revised generation of a modular micro-NMR detector, featuring an active sample volume of ∼ 100 nL, and an improvement of 87% in probe efficiency. The detector is capable of rapidly screening different samples using exchangeable, application-specific, MEMS-fabricated, microfluidic sample containers. In contrast to our previous design, the sample holder chips can be simply sealed with adhesive tape, with excellent adhesion due to the smooth surfaces surrounding the fluidic ports, and so withstand pressures of ∼2.5 bar, while simultaneously enabling high spectral resolution up to 0.62 Hz for H2O, due to its optimised geometry. We have additionally reworked the coil design and fabrication processes, replacing liquid photoresists by dry film stock, whose final thickness does not depend on accurate volume dispensing or precise levelling during curing. We further introduced mechanical alignment structures to avoid time-intensive optical alignment of the chip stacks during assembly, while we exchanged the laser-cut, PMMA spacers by diced glass spacers, which are not susceptible to melting during cutting. Doing so led to an overall simplification of the entire fabrication chain, while simultaneously increasing the yield, due to an improved uniformity of thickness of the individual layers, and in addition, due to more accurate vertical positioning of the wirebonded coils, now delimited by a post base plateau. We demonstrate the capability of the design by acquiring a 1H spectrum of ∼ 11 nmol sucrose dissolved in D2O, where we achieved a linewidth of 1.25 Hz for the TSP reference peak. Chemical shift imaging experiments were further recorded from voxel volumes of only ∼ 1.5 nL, which corresponded to amounts of just 1.5 nmol per voxel for a 1 M concentration. To extend the micro-detector to other nuclei of interest, we have implemented a trap circuit, enabling heteronuclear spectroscopy, demonstrated by two 1H/13C 2D HSQC

Functional studies using NMR

International Nuclear Information System (INIS)

McCready, V.R.; Leach, M.O.; Sutton; Ell, P.

1986-01-01

The object of this book is to discuss and evaluate an area of Nuclear Magnetic Resonance which to date has been less emphasized than it might be, namely the use of NMR for functional studies. The book commences with a discussion of the areas in which the NMR techniques might be needed due to deficiencies in other techniques. The physics of NMR especially relating to functional measurement are then explained. Technical factors in producing functional images are discussed and the use of paramagnetic substances for carrying out flow studies are detailed. Particular attention is paid to specific studies in the various organs. The book ends with a survey of imaging in each organ and the relation of NMR images to other techniques such as ultrasound, nuclear medicine and X-rays

Segmental isotope labeling of proteins for NMR structural study using a protein S tag for higher expression and solubility

International Nuclear Information System (INIS)

Kobayashi, Hiroshi; Swapna, G. V. T.; Wu, Kuen-Phon; Afinogenova, Yuliya; Conover, Kenith; Mao, Binchen; Montelione, Gaetano T.; Inouye, Masayori

2012-01-01

A common obstacle to NMR studies of proteins is sample preparation. In many cases, proteins targeted for NMR studies are poorly expressed and/or expressed in insoluble forms. Here, we describe a novel approach to overcome these problems. In the protein S tag-intein (PSTI) technology, two tandem 92-residue N-terminal domains of protein S (PrS 2 ) from Myxococcus xanthus is fused at the N-terminal end of a protein to enhance its expression and solubility. Using intein technology, the isotope-labeled PrS 2 -tag is replaced with non-isotope labeled PrS 2 -tag, silencing the NMR signals from PrS 2 -tag in isotope-filtered 1 H-detected NMR experiments. This method was applied to the E. coli ribosome binding factor A (RbfA), which aggregates and precipitates in the absence of a solubilization tag unless the C-terminal 25-residue segment is deleted (RbfAΔ25). Using the PrS 2 -tag, full-length well-behaved RbfA samples could be successfully prepared for NMR studies. PrS 2 (non-labeled)-tagged RbfA (isotope-labeled) was produced with the use of the intein approach. The well-resolved TROSY-HSQC spectrum of full-length PrS 2 -tagged RbfA superimposes with the TROSY-HSQC spectrum of RbfAΔ25, indicating that PrS 2 -tag does not affect the structure of the protein to which it is fused. Using a smaller PrS-tag, consisting of a single N-terminal domain of protein S, triple resonance experiments were performed, and most of the backbone 1 H, 15 N and 13 C resonance assignments for full-length E. coli RbfA were determined. Analysis of these chemical shift data with the Chemical Shift Index and heteronuclear 1 H– 15 N NOE measurements reveal the dynamic nature of the C-terminal segment of the full-length RbfA protein, which could not be inferred using the truncated RbfAΔ25 construct. CS-Rosetta calculations also demonstrate that the core structure of full-length RbfA is similar to that of the RbfAΔ25 construct.

Experiments and strategies for the assignment of fully13 C/15N-labelled polypeptides by solid state NMR

International Nuclear Information System (INIS)

Straus, Suzana K.; Bremi, Tobias; Ernst, Richard R.

1998-01-01

High-resolution heteronuclear NMR correlation experiments and strategies are proposed for the assignment of fully 13 C/ 15 N-labelled polypeptides in the solid state. By the combination of intra-residue and inter-residue 13 C- 15 N correlation experiments with 13 C- 13 C spin-diffusion studies, it becomes feasible to partially assign backbone and side-chain resonances in solid proteins. The performance of sequences using 15 N instead of 13 C detection is evaluated regarding sensitivity and resolution for a labelled dipeptide (L-Val-L-Phe). The techniques are used for a partial assignment of the 15 N and 13 C resonances in human ubiquitin

Targeted natural product isolation guided by HPLC-SPE-NMR: Constituents of Hubertia species

DEFF Research Database (Denmark)

Sprogoe, K.; Staek, D.; Jager, A.K.

2007-01-01

-hydroxyphenyl)acetyl]quinic acid (3), was performed. Finally, targeted isolation of 1 was achieved by SPE fractionation and preparative HPLC, followed by evaluation of its antioxidant and antimicrobial activity. In contrast to chlorogenic acid and 3,5-di-O-caffeoylquinic acid, which act as antioxidants...... full or partial identification of all major extract constituents and demonstrated the presence of unusual quinic acid derivatives containing the (1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl residue that exhibit strongly coupled ABXY patterns, the parameters of which were obtained by spin simulations....... Using homo- and heteronuclear 2D NMR data acquired in the HPLC-SPE-NMR mode, complete structure determination of three new natural products, i.e., 3,5-di-O-caffeoyl-4-O-[(1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl]quini c acid (1), its 2-hydroxy derivative (2), and 3,5-di-O-caffeoyl-4-O-[(4...

Development of uniformly stable isotope labeling system in higher plants for hetero-nuclear NMR experiments in vitro and in vivo

International Nuclear Information System (INIS)

Kikuchi, J.

2005-01-01

Full text: Novel methods for measurement of living systems are making new breakthroughs in life science. In the era of the metabolome (analysis of all measurable metabolites), a MS-based approach is considered to be the major technology, whereas a NMR-based method is recognized as minor technology due to its low sensitivity. Therefore, my laboratory is currently focusing to develop novel methodologies for an NMR-based metabolomics. This will be achieved by uniform stable isotope labeling of higher plants allowing application of multi-dimensional NMR experiments used in protein structure determination. Using these novel methods, I will analyze the dynamic molecular networks inside tissues. Especially, use of stable isotope labeling methods has enormous advantage for discrimination of incorporated or de novo synthesized compounds. Furthermore, potentiality of in vivo-NMR metabolomics will be discussed in the conference. (author)

Long-range dispersion interactions. I. Formalism for two heteronuclear atoms

International Nuclear Information System (INIS)

Zhang, J.-Y.; Mitroy, J.

2007-01-01

A general procedure for systematically evaluating the long-range dispersion interaction between two heteronuclear atoms in arbitrary states is outlined. The C 6 dispersion parameter can always be written in terms of sum rules involving oscillator strengths only and formulas for a number of symmetry cases are given. The dispersion coefficients for excited alkali-metal atoms interacting with the ground-state H and He are tabulated

Sine-squared shifted pulses for recoupling interactions in solid-state NMR

Science.gov (United States)

Jain, Mukul G.; Rajalakshmi, G.; Equbal, Asif; Mote, Kaustubh R.; Agarwal, Vipin; Madhu, P. K.

2017-06-01

Rotational-Echo DOuble-Resonance (REDOR) is a versatile experiment for measuring internuclear distance between two heteronuclear spins in solid-state NMR. At slow to intermediate magic-angle spinning (MAS) frequencies, the measurement of distances between strongly coupled spins is challenging due to rapid dephasing of magnetisation. This problem can be remedied by employing the pulse-shifted version of REDOR known as Shifted-REDOR (S-REDOR) that scales down the recoupled dipolar coupling. In this study, we propose a new variant of the REDOR sequence where the positions of the π pulses are determined by a sine-squared function. This new variant has scaling properties similar to S-REDOR. We use theory, numerical simulations, and experiments to compare the dipolar recoupling efficiencies and the experimental robustness of the three REDOR schemes. The proposed variant has advantages in terms of radiofrequency field requirements at fast MAS frequencies.

Natural abundance 15N NMR assignments delineate structural differences between intact and reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor III.

Science.gov (United States)

Krishnamoorthi, R; Nemmers, S; Tobias, B

1992-06-15

15N NMR assignments were made to the backbone amide nitrogen atoms at natural isotopic abundance of intact and reactive-site (Arg5-Ile6) hydrolyzed Cucurbita maxima trypsin inhibitor III (CMTI-III and CMTI-III*, respectively) by means of 2D proton-detected heteronuclear single bond chemical shift correlation (HSBC) spectroscopy, utilizing the previously made sequence-specific 1H NMR assignments (Krishnamoorthi et al. (1992) Biochemistry 31, 898-904). Comparison of the 15N chemical shifts of the two forms of the inhibitor molecule revealed significant changes not only for residues located near the reactive-site region, but also for those distantly located. Residues Cys3, Arg5, Leu7, Met8, Cys10, Cys16, Glu19, His25, Tyr27, Cys28 and Gly29 showed significant chemical shift changes ranging from 0.3 to 6.1 ppm, thus indicating structural perturbations that were transmitted throughout the molecule. These findings confirm the earlier conclusions based on 1H NMR investigations.

A new carbamidemethyl-linked lanthanoid chelating tag for PCS NMR spectroscopy of proteins in living HeLa cells

Energy Technology Data Exchange (ETDEWEB)

Hikone, Yuya [Tokyo Metropolitan University, Department of Chemistry, Graduate School of Science and Engineering (Japan); Hirai, Go [RIKEN, Synthetic Organic Chemistry Laboratory (Japan); Mishima, Masaki [Tokyo Metropolitan University, Department of Chemistry, Graduate School of Science and Engineering (Japan); Inomata, Kohsuke [RIKEN, Quantitative Biology Center (Japan); Ikeya, Teppei; Arai, Souichiro [Tokyo Metropolitan University, Department of Chemistry, Graduate School of Science and Engineering (Japan); Shirakawa, Masahiro [Japan Agency for Medical Research and Development, AMED-CREST (Japan); Sodeoka, Mikiko [RIKEN, Synthetic Organic Chemistry Laboratory (Japan); Ito, Yutaka, E-mail: ito-yutaka@tmu.ac.jp [Tokyo Metropolitan University, Department of Chemistry, Graduate School of Science and Engineering (Japan)

2016-10-15

Structural analyses of proteins under macromolecular crowding inside human cultured cells by in-cell NMR spectroscopy are crucial not only for explicit understanding of their cellular functions but also for applications in medical and pharmaceutical sciences. In-cell NMR experiments using human cultured cells however suffer from low sensitivity, thus pseudocontact shifts from protein-tagged paramagnetic lanthanoid ions, analysed using sensitive heteronuclear two-dimensional correlation NMR spectra, offer huge potential advantage in obtaining structural information over conventional NOE-based approaches. We synthesised a new lanthanoid-chelating tag (M8-CAM-I), in which the eight-fold, stereospecifically methylated DOTA (M8) scaffold was retained, while a stable carbamidemethyl (CAM) group was introduced as the functional group connecting to proteins. M8-CAM-I successfully fulfilled the requirements for in-cell NMR: high-affinity to lanthanoid, low cytotoxicity and the stability under reducing condition inside cells. Large PCSs for backbone N–H resonances observed for M8-CAM-tagged human ubiquitin mutant proteins, which were introduced into HeLa cells by electroporation, demonstrated that this approach readily provides the useful information enabling the determination of protein structures, relative orientations of domains and protein complexes within human cultured cells.

A new carbamidemethyl-linked lanthanoid chelating tag for PCS NMR spectroscopy of proteins in living HeLa cells.

Science.gov (United States)

Hikone, Yuya; Hirai, Go; Mishima, Masaki; Inomata, Kohsuke; Ikeya, Teppei; Arai, Souichiro; Shirakawa, Masahiro; Sodeoka, Mikiko; Ito, Yutaka

2016-10-01

Structural analyses of proteins under macromolecular crowding inside human cultured cells by in-cell NMR spectroscopy are crucial not only for explicit understanding of their cellular functions but also for applications in medical and pharmaceutical sciences. In-cell NMR experiments using human cultured cells however suffer from low sensitivity, thus pseudocontact shifts from protein-tagged paramagnetic lanthanoid ions, analysed using sensitive heteronuclear two-dimensional correlation NMR spectra, offer huge potential advantage in obtaining structural information over conventional NOE-based approaches. We synthesised a new lanthanoid-chelating tag (M8-CAM-I), in which the eight-fold, stereospecifically methylated DOTA (M8) scaffold was retained, while a stable carbamidemethyl (CAM) group was introduced as the functional group connecting to proteins. M8-CAM-I successfully fulfilled the requirements for in-cell NMR: high-affinity to lanthanoid, low cytotoxicity and the stability under reducing condition inside cells. Large PCSs for backbone N-H resonances observed for M8-CAM-tagged human ubiquitin mutant proteins, which were introduced into HeLa cells by electroporation, demonstrated that this approach readily provides the useful information enabling the determination of protein structures, relative orientations of domains and protein complexes within human cultured cells.

A new carbamidemethyl-linked lanthanoid chelating tag for PCS NMR spectroscopy of proteins in living HeLa cells

International Nuclear Information System (INIS)

Hikone, Yuya; Hirai, Go; Mishima, Masaki; Inomata, Kohsuke; Ikeya, Teppei; Arai, Souichiro; Shirakawa, Masahiro; Sodeoka, Mikiko; Ito, Yutaka

2016-01-01

Structural analyses of proteins under macromolecular crowding inside human cultured cells by in-cell NMR spectroscopy are crucial not only for explicit understanding of their cellular functions but also for applications in medical and pharmaceutical sciences. In-cell NMR experiments using human cultured cells however suffer from low sensitivity, thus pseudocontact shifts from protein-tagged paramagnetic lanthanoid ions, analysed using sensitive heteronuclear two-dimensional correlation NMR spectra, offer huge potential advantage in obtaining structural information over conventional NOE-based approaches. We synthesised a new lanthanoid-chelating tag (M8-CAM-I), in which the eight-fold, stereospecifically methylated DOTA (M8) scaffold was retained, while a stable carbamidemethyl (CAM) group was introduced as the functional group connecting to proteins. M8-CAM-I successfully fulfilled the requirements for in-cell NMR: high-affinity to lanthanoid, low cytotoxicity and the stability under reducing condition inside cells. Large PCSs for backbone N–H resonances observed for M8-CAM-tagged human ubiquitin mutant proteins, which were introduced into HeLa cells by electroporation, demonstrated that this approach readily provides the useful information enabling the determination of protein structures, relative orientations of domains and protein complexes within human cultured cells.

Functional studies using NMR

International Nuclear Information System (INIS)

McCready, V.R.; Leach, M.; Ell, P.J.

1987-01-01

This volume is based on a series of lectures delivered at a one-day teaching symposium on functional and metabolic aspects of NMR measurements held at the Middlesex Hospital Medical School on 1st September 1985 as a part of the European Nuclear Medicine Society Congress. Currently the major emphasis in medical NMR in vivo is on its potential to image and display abnormalities in conventional radiological images, providing increased contrast between normal and abnormal tissue, improved definition of vasculature, and possibly an increased potential for differential diagnosis. Although these areas are undeniably of major importance, it is probable that NMR will continue to complement conventional measurement methods. The major potential benefits to be derived from in vivo NMR measurements are likely to arise from its use as an instrument for functional and metabolic studies in both clinical research and in the everyday management of patients. It is to this area that this volume is directed

Isolation and characterisation of three new anthraquinone secondary metabolites from Symplocos racemosa.

Science.gov (United States)

Farooq, Umar; Naz, Sadia; Khan, Ajmal; Khan, Sara; Khan, Afsar; Ali, Mumtaz; Khan, Saleha Suleman

2016-01-01

Three new anthraquinone secondary metabolites were isolated from Symplocos racemosa, a small tree of family symplocaceae. The structures of compounds (1-3) were elucidated to be 1,4-dihydroxy-6-(ethoxymethyl)-8-propylanthracene-9,10-dione (1), 1,4-dihydroxy-6-(hydroxymethyl)-8-butylanthracene-9,10-dione (2) and 1,4-dihydroxy-6-(hydroxymethyl)-8-propyl anthracene-9,10-dione (3) using their spectral data, i.e. through IR, UV, (1)H NMR, (13)C NMR and two-dimensional (2D) NMR techniques including heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation and correlation spectroscopy.

Avoiding bias effects in NMR experiments for heteronuclear dipole-dipole coupling determinations: principles and application to organic semiconductor materials.

Science.gov (United States)

Kurz, Ricardo; Cobo, Marcio Fernando; de Azevedo, Eduardo Ribeiro; Sommer, Michael; Wicklein, André; Thelakkat, Mukundan; Hempel, Günter; Saalwächter, Kay

2013-09-16

Carbon-proton dipole-dipole couplings between bonded atoms represent a popular probe of molecular dynamics in soft materials or biomolecules. Their site-resolved determination, for example, by using the popular DIPSHIFT experiment, can be challenged by spectral overlap with nonbonded carbon atoms. The problem can be solved by using very short cross-polarization (CP) contact times, however, the measured modulation curves then deviate strongly from the theoretically predicted shape, which is caused by the dependence of the CP efficiency on the orientation of the CH vector, leading to an anisotropic magnetization distribution even for isotropic samples. Herein, we present a detailed demonstration and explanation of this problem, as well as providing a solution. We combine DIPSHIFT experiments with the rotor-directed exchange of orientations (RODEO) method, and modifications of it, to redistribute the magnetization and obtain undistorted modulation curves. Our strategy is general in that it can also be applied to other types of experiments for heteronuclear dipole-dipole coupling determinations that rely on dipolar polarization transfer. It is demonstrated with perylene-bisimide-based organic semiconductor materials, as an example, in which measurements of dynamic order parameters reveal correlations of the molecular dynamics with the phase structure and functional properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Targeted natural product isolation guided by HPLC-SPE-NMR: constituents of Hubertia species.

Science.gov (United States)

Sprogøe, Kennett; Staerk, Dan; Jäger, Anna K; Adsersen, Anne; Hansen, Steen Honoré; Witt, Matthias; Landbo, Anne-Katrine R; Meyer, Anne S; Jaroszewski, Jerzy W

2007-09-01

The hyphenated technique, high-performance liquid chromatography-solid-phase extraction-nuclear magnetic resonance spectroscopy (HPLC-SPE-NMR), has been applied for rapid identification of novel natural products in crude extracts of Hubertia ambavilla and Hubertia tomentosa. The technique allowed full or partial identification of all major extract constituents and demonstrated the presence of unusual quinic acid derivatives containing the (1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl residue that exhibit strongly coupled ABXY patterns, the parameters of which were obtained by spin simulations. Using homo- and heteronuclear 2D NMR data acquired in the HPLC-SPE-NMR mode, complete structure determination of three new natural products, i.e., 3,5-di-O-caffeoyl-4-O-[(1-hydroxy-4-oxocyclohexa-2,5-dienyl)acetyl]quinic acid (1), its 2-hydroxy derivative (2), and 3,5-di-O-caffeoyl-4-O-[(4-hydroxyphenyl)acetyl]quinic acid (3), was performed. Finally, targeted isolation of 1 was achieved by SPE fractionation and preparative HPLC, followed by evaluation of its antioxidant and antimicrobial activity. In contrast to chlorogenic acid and 3,5-di-O-caffeoylquinic acid, which act as antioxidants, compound 1 proved at the same conditions to possess prooxidant activity in an assay evaluating the oxidation of human low-density lipoprotein induced by Cu(2+).

Performance of new 400-MHz HTS power-driven magnet NMR technology on typical pharmaceutical API, cinacalcet HCl.

Science.gov (United States)

Silva Elipe, Maria Victoria; Donovan, Neil; Krull, Robert; Pooke, Donald; Colson, Kimberly L

2018-04-17

After years towards higher field strength magnets, nuclear magnetic resonance (NMR) technology in commercial instruments in the past decade has expanded at low and high magnetic fields to take advantage of new opportunities. At lower field strengths, permanent magnets are well established, whereas for midrange and high field, developments utilize superconducting magnets cooled with cryogenic liquids. Recently, the desire to locate NMR spectrometers in nontypical NMR laboratories has created interest in the development of cryogen-free magnets. These magnets require no cryogenic maintenance, eliminating routine filling and large cryogen dewars in the facility. Risks of spontaneous quenches and safety concerns when working with cryogenic liquids are eliminated. The highest field commercially available cryogen-free NMR magnet previously reported was at 4.7 T in 2013. Here we tested a prototype cryogen-free 9.4-T power-driven high-temperature-superconducting (HTS) magnet mated to commercial NMR spectrometer electronics. We chose cinacalcet HCl, a typical active pharmaceutical ingredient, to evaluate its performance towards structure elucidation. Satisfactory standard 1D and 2D homonuclear and heteronuclear NMR results were obtained and compared with those from a standard 9.4-T cryogenically cooled superconducting NMR instrument. The results were similar between both systems with minor differences. Further comparison with different shims and probes in the HTS magnet system confirmed that the magnet homogeneity profile could be matched with commercially available NMR equipment for optimal results. We conclude that HTS magnet technology works well providing results comparable with those of standard instruments, leading us to investigate additional applications for this magnet technology outside a traditional NMR facility. Copyright © 2018 John Wiley & Sons, Ltd.

15N NMR relaxation studies of calcium-loaded parvalbumin show tight dynamics compared to those of other EF-hand proteins

DEFF Research Database (Denmark)

Baldellon, C; Alattia, J R; Strub, M P

1998-01-01

Dynamics of the rat alpha-parvalbumin calcium-loaded form have been determined by measurement of 15N nuclear relaxation using proton-detected heteronuclear NMR spectroscopy. The relaxation data were analyzed using spectral density functions and the Lipari-Szabo formalism. The major dynamic features...... for the rat alpha-parvalbumin calcium-loaded form are (1) the extreme rigidity of the helix-loop-helix EF-hand motifs and the linker segment connecting them, (2) the N and C termini of the protein being restricted in their mobility, (3) a conformational exchange occurring at the kink of helix D, and (4...... properties which are conserved in the EF-hand domains from different members of this superfamily: (1) a tendency toward higher mobility of NH vectors at relative position 2 in the Ca2+-binding loop, (2) a restricted mobility for the other residues in the binding loop, and (3) an overall rigidity...

Identification and quantification of flavonoids and ellagic acid derivatives in therapeutically important Drosera species by LC-DAD, LC-NMR, NMR, and LC-MS.

Science.gov (United States)

Zehl, Martin; Braunberger, Christina; Conrad, Jürgen; Crnogorac, Marija; Krasteva, Stanimira; Vogler, Bernhard; Beifuss, Uwe; Krenn, Liselotte

2011-06-01

Droserae herba is a drug commonly used for treatment of convulsive or whooping cough since the seventeenth century. Because of the contribution of flavonoids and ellagic acid derivatives to the therapeutic activity of Droserae herba, an LC-DAD method has been developed for quantification of these analytes in four Drosera species used in medicine (Drosera anglica, D. intermedia, D. madagascariensis, and D. rotundifolia). During elaboration of the method 13 compounds, including three substances not previously described for Drosera species, were detected and unambiguously identified by means of extensive LC-MS and LC-NMR experiments and by off-line heteronuclear 2D NMR after targeted isolation. The most prominent component of D. rotundifolia and D. anglica, 2″-O-galloylhyperoside, with myricetin-3-O-β-glucopyranoside and kaempferol-3-O-(2″-O-galloyl)-β-galactopyranoside, were identified for the very first time in this genus. The LC-DAD method for quantification was thoroughly validated, and enables, for the first time, separation and precise analysis of these analytes in Droserae herba. Simple sample preparation and use of a narrow-bore column guarantee low cost and simplicity of the suggested system, which is excellently suited to quality control of the drug or herbal medicinal products containing this drug.

HN-NCA heteronuclear TOCSY-NH experiment for {sup 1}H{sup N} and {sup 15}N sequential correlations in ({sup 13}C, {sup 15}N) labelled intrinsically disordered proteins

Energy Technology Data Exchange (ETDEWEB)

Wiedemann, Christoph; Goradia, Nishit; Häfner, Sabine [Leibniz Institute for Age Research, Fritz Lipmann Institute, Research Group Biomolecular NMR Spectroscopy (Germany); Herbst, Christian [Ubon Ratchathani University, Department of Physics, Faculty of Science (Thailand); Görlach, Matthias; Ohlenschläger, Oliver; Ramachandran, Ramadurai, E-mail: raman@fli-leibniz.de [Leibniz Institute for Age Research, Fritz Lipmann Institute, Research Group Biomolecular NMR Spectroscopy (Germany)

2015-10-15

A simple triple resonance NMR experiment that leads to the correlation of the backbone amide resonances of each amino acid residue ‘i’ with that of residues ‘i−1’ and ‘i+1’ in ({sup 13}C, {sup 15}N) labelled intrinsically disordered proteins (IDPs) is presented. The experimental scheme, {HN-NCA heteronuclear TOCSY-NH}, exploits the favourable relaxation properties of IDPs and the presence of {sup 1}J{sub CαN} and {sup 2}J{sub CαN} couplings to transfer the {sup 15}N{sub x} magnetisation from amino acid residue ‘i’ to adjacent residues via the application of a band-selective {sup 15}N–{sup 13}C{sup α} heteronuclear cross-polarisation sequence of ∼100 ms duration. Employing non-uniform sampling in the indirect dimensions, the efficacy of the approach has been demonstrated by the acquisition of 3D HNN chemical shift correlation spectra of α-synuclein. The experimental performance of the RF pulse sequence has been compared with that of the conventional INEPT-based HN(CA)NH pulse scheme. As the availability of data from both the HCCNH and HNN experiments will make it possible to use the information extracted from one experiment to simplify the analysis of the data of the other and lead to a robust approach for unambiguous backbone and side-chain resonance assignments, a time-saving strategy for the simultaneous collection of HCCNH and HNN data is also described.

Increasing the sensitivity of NMR diffusion measurements by paramagnetic longitudinal relaxation enhancement, with application to ribosome–nascent chain complexes

International Nuclear Information System (INIS)

Chan, Sammy H. S.; Waudby, Christopher A.; Cassaignau, Anaïs M. E.; Cabrita, Lisa D.; Christodoulou, John

2015-01-01

The translational diffusion of macromolecules can be examined non-invasively by stimulated echo (STE) NMR experiments to accurately determine their molecular sizes. These measurements can be important probes of intermolecular interactions and protein folding and unfolding, and are crucial in monitoring the integrity of large macromolecular assemblies such as ribosome–nascent chain complexes (RNCs). However, NMR studies of these complexes can be severely constrained by their slow tumbling, low solubility (with maximum concentrations of up to 10 μM), and short lifetimes resulting in weak signal, and therefore continuing improvements in experimental sensitivity are essential. Here we explore the use of the paramagnetic longitudinal relaxation enhancement (PLRE) agent NiDO2A on the sensitivity of 15 N XSTE and SORDID heteronuclear STE experiments, which can be used to monitor the integrity of these unstable complexes. We exploit the dependence of the PLRE effect on the gyromagnetic ratio and electronic relaxation time to accelerate recovery of 1 H magnetization without adversely affecting storage on N z during diffusion delays or introducing significant transverse relaxation line broadening. By applying the longitudinal relaxation-optimized SORDID pulse sequence together with NiDO2A to 70S Escherichia coli ribosomes and RNCs, NMR diffusion sensitivity enhancements of up to 4.5-fold relative to XSTE are achieved, alongside ∼1.9-fold improvements in two-dimensional NMR sensitivity, without compromising the sample integrity. We anticipate these results will significantly advance the use of NMR to probe dynamic regions of ribosomes and other large, unstable macromolecular assemblies.Graphical Abstract

Assessment of protein solution versus crystal structure determination using spin- diffusion-suppressed NOE and heteronuclear relaxation data

International Nuclear Information System (INIS)

LeMaster, David M.

1997-01-01

A spin-diffusion-suppressed NOE buildup series has been measured for E. coli thioredoxin.The extensive 13C and 15N relaxation data previously reported for this protein allow for direct interpretation of dynamical contributions to the 1H-1H cross-relaxation rates for a large proportion of the NOE cross peaks. Estimates of the average accuracy for these derived NOE distances are bounded by 4% and 10%, based on a comparison to the corresponding X-ray distances. An independent fluctuation model is proposed for prediction of the dynamical corrections to 1H-1H cross-relaxation rates, based solely on experimental structural and heteronuclear relaxation data. This analysis is aided by the demonstration that heteronuclear order parameters greater than 0.6 depend only on the variance of the H-X bond orientation,independent of the motional model in either one- or two-dimensional diffusion (i.e., 1- S2 = 3/4 sin2 2 θσ). The combination of spin-diffusion-suppressed NOE data and analysis of dynamical corrections to 1H-1H cross-relaxation rates based on heteronuclear relaxation data has allowed for a detailed interpretation of various discrepancies between the reported solution and crystal structures

NMR techniques in the study of cardiovascular structure and functions

International Nuclear Information System (INIS)

Osbakken, M.; Haselgrove, J.

1987-01-01

The chapter titles of this book are: Introduction to NMR Techniques;Theory of NMR Probe Design;Overview of Magnetic Resonance Imaging to Study the Cardiovascular System;Vascular Anatomy and Physiology Studied with NMR Techniques;Assessment of Myocardial Ischemia and Infarction by Nuclear Magnetic Resonance Imaging;The Use of MRI in Congenital Heart Disease;Cardiomyopathies and Myocarditis Studied with NMR Techniques;Determination of Myocardial Mechanical Function with Magnetic Resonance Imaging Techniques;Determination of Flow Using NMR Techniques;The Use of Contrast Agents in Cardiac MRI;Can Cardiovascular Disease Be Effectively Evaluated with NMR Spectroscopy? NMR Studies of ATP Synthesis Reactions in the Isolated Heart;Studies of Intermediary Metabolism in the Heart by 13C NMR Spectroscopy;23Na and 39K NMR Spectroscopic Studies of the Intact Beating Heart;and Evaluation of Skeletal Muscle Metabolism in Patients with Congestive Heart Failure Using Phosphorus Nuclear Magnetic Resonance

Quantum atom-heteronuclear molecule dark state: Role of population imbalance

International Nuclear Information System (INIS)

Jing Hui; Cui Shuai

2010-01-01

Recently, the finite-number effect of initial atoms in coherent atom-molecule conversion was investigated by Zhao et al. [Phys. Rev. Lett. 101, 010401 (2008)]. Here, by extending to the atom-heteronuclear molecule dark state, we find that the initial populations imbalance of the atoms plays a significant role in quantum conversion rate and adiabatic fidelity. In particular, even for the finite total number of imbalanced two-species atoms, the mean-field conversion rate, contrary to the general belief, still can be remarkably close to the exact quantum results.

1H and 13C NMR Chemical Shift Assignments and Conformational Analysis for the Two Diastereomers of the Vitamin K Epoxide Reductase Inhibitor Brodifacoum

International Nuclear Information System (INIS)

Cort, John R.; Cho, Herman M.

2009-01-01

Proton and 13C NMR chemical shift assignments and 1H-1H scalar couplings for the two diastereomers of the vitamin K epoxide reductase (VKOR) inhibitor brodifacoum have been determined from acetone solutions containing both diastereomers. Data were obtained from homo- and heteronuclear correlation spectra acquired at 1H frequencies of 750 and 900 MHz over a 268-303 K temperature range. Conformations inferred from scalar coupling and 1-D NOE measurements exhibit large differences between the diastereomers. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Interaction-induced decay of a heteronuclear two-atom system

Science.gov (United States)

Xu, Peng; Yang, Jiaheng; Liu, Min; He, Xiaodong; Zeng, Yong; Wang, Kunpeng; Wang, Jin; Papoular, D. J.; Shlyapnikov, G. V.; Zhan, Mingsheng

2015-01-01

Two-atom systems in small traps are of fundamental interest for understanding the role of interactions in degenerate cold gases and for the creation of quantum gates in quantum information processing with single-atom traps. One of the key quantities is the inelastic relaxation (decay) time when one of the atoms or both are in a higher hyperfine state. Here we measure this quantity in a heteronuclear system of 87Rb and 85Rb in a micro optical trap and demonstrate experimentally and theoretically the presence of both fast and slow relaxation processes, depending on the choice of the initial hyperfine states. This experimental method allows us to single out a particular relaxation process thus provides an extremely clean platform for collisional physics studies. Our results have also implications for engineering of quantum states via controlled collisions and creation of two-qubit quantum gates. PMID:26199051

2D NMR studies of biomolecules

International Nuclear Information System (INIS)

Lamerichs, R.M.J.N.

1989-01-01

The work described in this thesis comprises two related subjects. The first part describes methods to derive high-resolution structures of proteins in solution using two-dimensional (2-D) NMR. The second part describes 2-D NMR studies on the interaction between proteins and DNA. (author). 261 refs.; 52 figs.; 23 tabs

Hyphenation of solid-phase extraction with liquid chromatography and nuclear magnetic resonance: application of HPLC-DAD-SPE-NMR to identification of constituents of Kanahia laniflora.

Science.gov (United States)

Clarkson, Cailean; Staerk, Dan; Hansen, Steen Honoré; Jaroszewski, Jerzy W

2005-06-01

The introduction of on-line solid-phase extraction (SPE) in HPLC-NMR has dramatically enhanced the sensitivity of this technique by concentration of the analytes in a small-volume NMR flow cell and by increasing the amount of the analyte by multiple peak trapping. In this study, the potential of HPLC-DAD-SPE-NMR hyphenation was demonstrated by structure determination of complex constituents of flower, leaf, root, and stem extracts of an African medicinal plant Kanahia laniflora. The technique was shown to allow acquisition of high-quality homo- and heteronuclear 2D NMR data following analytical-scale HPLC separation of extract constituents. Four flavonol glycosides [kaempferol 3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside; kaempferol 3-O-(2,6-di-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside; quercetin 3-O-(2,6-di-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside (rutin); and isorhamnetin, 3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside] and three 5alpha-cardenolides [coroglaucigenin 3-O-6-deoxy-beta-d-allopyranoside; coroglaucigenin 3-O-(4-O-beta-d-glucopyranosyl)-6-deoxy-beta-d-glucopyranoside; 3'-O-acetyl-3'-epiafroside] were identified, with complete assignments of 1H and 13C resonances based on HSQC and HMBC spectra whenever required. Confirmation of the structures was provided by HPLC-MS data. The HPLC-DAD-SPE-NMR technique therefore speeds up the dereplication of complex mixtures of natural origin significantly, by characterization of individual extract components prior to preparative isolation work.

The direct measurement of the heteronuclear chemical shifts relative to tetramethylsilane

International Nuclear Information System (INIS)

Moritz, A.G.

1988-12-01

The measurement of heteronuclear chemical shifts using absolute frequencies of the heteronucleus and the 1 H resonance of tetramethylsilane has been examined. This method avoids the problems associated with external standards and gives results which can be obtained quickly and with high precision. The method has a number of advantages in the accurate measurement of chemical shifts, as for example 31 P in chemical warfare agents and related chemicals and allows multinuclear data to be obtained without dynamic range or potential interference problems. 15 refs., 4 tabs

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

Science.gov (United States)

Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

2015-04-01

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

International Nuclear Information System (INIS)

Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

2015-01-01

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

Energy Technology Data Exchange (ETDEWEB)

Takegoshi, K., E-mail: takeyan@kuchem.kyoto-u.ac.jp; Miyazawa, Norihiro [Division of Chemistry, Graduate School of Science, Kyoto University, 606-8502 Kyoto (Japan); Sharma, Kshama [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Madhu, P. K. [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

2015-04-07

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

Heteronuclear proton assisted recoupling

Science.gov (United States)

De Paëpe, Gaël; Lewandowski, Józef R.; Loquet, Antoine; Eddy, Matt; Megy, Simon; Böckmann, Anja; Griffin, Robert G.

2011-03-01

We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular 15N-13C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between 1H-15N and 1H-13C dipolar couplings to mediate zero- and/or double-quantum 15N-13C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N±C∓Hz (ZQ) or N±C±Hz (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with 15N-13C spectra of two uniformly 13C,15N labeled model microcrystalline proteins—GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW = 2 × 10.4 kDa). The spectra acquired at high magic angle spinning frequencies (ωr/2π > 20 kHz) and magnetic fields (ω0H/2π = 700-900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer 15N-13C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein.

New sesquiterpenes from Euonymus europaeus (Celastraceae).

Science.gov (United States)

Descoins, Charles; Bazzocchi, Isabel López; Ravelo, Angel Gutiérrez

2002-02-01

A new sesquiterpene evoninate alkaloid (1), and two sesquiterpenes (2, 3) with a dihydro-beta-agarofuran skeleton, along with three known sesquiterpenes (4-6), were isolated from the seeds of Euonymus europaeus. Their structures were elucidated by high resolution mass analysis, and one- and two-dimensional (1D and 2D) NMR spectroscopy, including homonuclear and heteronuclear correlation [correlation spectroscopy (COSY), rotating frame Overhauser enhancement spectroscopy (ROESY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC)] experiments.

Mechanism of phosphoryl transfer and protein-protein interaction in the PTS system-an NMR study

Energy Technology Data Exchange (ETDEWEB)

Rajagopal, P.; Klevit, R.E. [Univ. of Washington, Seattle, WA (United States)

1994-12-01

HPr and Enzyme IIA{sup Glc} are two of the components of the bacterial PTS (phosphoenolpyruvate: sugar phosphotranferase system) and are involved in the phosphorylation and concomitant translocation of sugars across the membrane. These PTS protein complexes also regulate sugar transport. HPr, phosphorylated at a histidine N1 site by Enzyme I and phosphoenol pyruvate, transfers the phosphoryl group to a histidine N3 position in Enzyme IIA{sup Glc}. HPrs from Gram-positive bacteria undergo regulatory phosphorylation at Ser{sup 46}, whereby phosphorylation of the histidine residue is inhibited. Conversely, histidine phosphorylation inhibits phosphorylation at Ser{sup 46}. HPrs from Gram-negative bacteria possess a serine residue at position 46, but do not undergo regulatory phosphorylation. HPr forms an open-faced sandwich structure with a four-strand S-sheet and 2 to 3 helices lying on top of the sheet. The active-site histidine and Ser{sup 46} occur in conformationally flexible regions. P-His-HPr from the Gram-positive bacterium Bacillus subtilus has been investigated by both homonuclear and heteronuclear two-dimensional and three-dimensional NMR experiments using an in-situ enzymatic regeneration system to maintain a constant level of P-His-HPr. The results show that localized conformational changes occur in the vicinity of the active-site histidine and also near Ser{sup 46}. HPr-Enzyme IIA{sup Glc} complexes from both Bacillus subtilis and Gram-negative Escherichia coli were also studied by a variety of {sup 15}N-edited two-dimensional NMR experiments, which were performed on uniformly {sup 15}N-labeled HPr complexed to unlabeled Enzyme IIA{sup Glc}. The complex is in fast exchange with a molecular weight of about 27 kDa. The focus of our work is to assess the changes undergone by HPr (the smaller of the two components), and so all the experiments were performed with excess Enzyme IIA present in the system.

Two-dimensional 1H and 31P NMR spectra and restrained molecular dynamics structure of an extrahelical adenosine tridecamer oligodeoxyribonucleotide duplex

International Nuclear Information System (INIS)

Nikonowicz, E.; Roongta, V.; Jones, C.R.; Gorenstein, D.G.

1989-01-01

Assignment of the 1H and 31P NMR spectra of an extrahelical adenosine tridecamer oligodeoxyribonucleotide duplex, d(CGCAGAATTCGCG)2, has been made by two-dimensional 1H-1H and heteronuclear 31P-1H correlated spectroscopy. The downfield 31P resonance previously noted by Patel et al. (1982) has been assigned by both 17O labeling of the phosphate as well as a pure absorption phase constant-time heteronuclear 31P-1H correlated spectrum and has been associated with the phosphate on the 3' side of the extrahelical adenosine. JH3'-P coupling constants for each of the phosphates of the tridecamer were obtained from the 1H-31P J-resolved selective proton-flip 2D spectrum. By use of a modified Karplus relationship the C4-C3'-O3-P torsional angles (epsilon) were obtained. There exists a good linear correlation between 31P chemical shifts and the epsilon torsional angle. The 31P chemical shifts and epsilon torsional angles follow the general observation that the more internal the phosphate is located within the oligonucleotide sequence, the more upfield the 31P resonance occurs. Because the extrahelical adenosine significantly distorts the deoxyribose phosphate backbone conformation even several bases distant from the extrahelical adenosine, 31P chemical shifts show complex site- and sequence-specific variations. Modeling and NOESY distance-restrained energy minimization and restrained molecular dynamics suggest that the extrahelical adenosine stacks into the duplex. However, a minor conformation is also observed in the 1H NMR, which could be associated with a structure in which the extrahelical adenosine loops out into solution

Characterization of Silicon Nanocrystal Surfaces by Multidimensional Solid-State NMR Spectroscopy

International Nuclear Information System (INIS)

Hanrahan, Michael P.; Fought, Ellie L.; Windus, Theresa L.; Wheeler, Lance M.; Anderson, Nicholas C.

2017-01-01

The chemical and photophysical properties of silicon nanocrystals (Si NCs) are strongly dependent on the chemical composition and structure of their surfaces. Here we use fast magic angle spinning (MAS) and proton detection to enable the rapid acquisition of dipolar and scalar 2D 1 H– 29 Si heteronuclear correlation (HETCOR) solid-state NMR spectra and reveal a molecular picture of hydride-terminated and alkyl-functionalized surfaces of Si NCs produced in a nonthermal plasma. 2D 1 H– 29 Si HETCOR and dipolar 2D 1 H– 1 H multiple-quantum correlation spectra illustrate that resonances from surface mono-, di-, and trihydride groups cannot be resolved, contrary to previous literature assignments. Instead the 2D NMR spectra illustrate that there is large distribution of 1 H and 29 Si chemical shifts for the surface hydride species in both the as-synthesized and functionalized Si NCs. However, proton-detected 1 H– 29 Si refocused INEPT experiments can be used to unambiguously differentiate NMR signals from the different surface hydrides. Varying the 29 Si evolution time in refocused INEPT experiments and fitting the oscillation of the NMR signals allows for the relative populations of the different surface hydrides to be estimated. This analysis confirms that monohydride species are the predominant surface species on the as-synthesized Si NCs. A reduction in the populations of the di- and trihydrides is observed upon functionalization with alkyl groups, consistent with our previous hypothesis that the trihydride, or silyl (*SiH 3 ), group is primarily responsible for initiating surface functionalization reactions. Density functional theory (DFT) calculations were used to obtain quantum chemical structural models of the Si NC surface and reproduce the observed 1 H and 29 Si chemical shifts. Furthermore, the approaches outlined here will be useful to obtain a more detailed picture of surface structures for Si NCs and other hydride-passivated nanomaterials.

PASA - A Program for Automated Protein NMR Backbone Signal Assignment by Pattern-Filtering Approach

International Nuclear Information System (INIS)

Xu Yizhuang; Wang Xiaoxia; Yang Jun; Vaynberg, Julia; Qin Jun

2006-01-01

We present a new program, PASA (Program for Automated Sequential Assignment), for assigning protein backbone resonances based on multidimensional heteronuclear NMR data. Distinct from existing programs, PASA emphasizes a per-residue-based pattern-filtering approach during the initial stage of the automated 13 C α and/or 13 C β chemical shift matching. The pattern filter employs one or multiple constraints such as 13 C α /C β chemical shift ranges for different amino acid types and side-chain spin systems, which helps to rule out, in a stepwise fashion, improbable assignments as resulted from resonance degeneracy or missing signals. Such stepwise filtering approach substantially minimizes early false linkage problems that often propagate, amplify, and ultimately cause complication or combinatorial explosion of the automation process. Our program (http://www.lerner.ccf.org/moleccard/qin/) was tested on four representative small-large sized proteins with various degrees of resonance degeneracy and missing signals, and we show that PASA achieved the assignments efficiently and rapidly that are fully consistent with those obtained by laborious manual protocols. The results demonstrate that PASA may be a valuable tool for NMR-based structural analyses, genomics, and proteomics

Polymeric proanthocyanidins 13C NMR studies of procyanidins

Science.gov (United States)

Lawrence J. Porter; Roger H. Newman; Lai Yeap Foo; Herbert Wong; Richard W. Hemingway

1982-01-01

Proanthocyanidin polymers have been shown to consist entirely of flavan-3-ol units by a combination of techniques including 13C n.m.r. spectroscopy. The 13C n.m.r. spectra of the polymers and related molecules are now considered in more detail. Prior to this study UC n.m.r. data has been published of procyanidins and...

Applications of NMR to studies of tissue metabolism

International Nuclear Information System (INIS)

Avison, M.J.; Hetherington, H.P.; Shulman, R.G.

1986-01-01

From its beginnings as a tool for the elucidation of biochemical pathways and bioenergetic status in unicellular organisms, the field of NMR studie in vivo has grown to encompass not only the study of isolated perfused organs, but also the study of various aspects of the biochemistry, physiology, and pathophysiology of these same organs in the intact animal. In recent years several groups have begun to extend the techniques developed in animals to the study of clinically relevant conditions in humans. A comprehensive review of all areas of NMR studies in vivo would be either unacceptably long or very superficial. For this reason the authors have restricted this review to studies published since 1980, except where an earlier study is particularly relevant to the topic under discussion. Furthermore, they have concentrated on areas that have been extending the scope of NMR in vivo. One specific omission is review of NMR studies of tumors, since a comprehensive review has recently appeared

Structural investigations of substituted indolizine derivatives by NMR studies

International Nuclear Information System (INIS)

Furdui, Bianca; Dinica, Rodica; Demeunynck, Martine; Druta, Ioan

2008-01-01

Owing to the increasing importance of indolizine heterocycles in the field of biology and pharmacology we have synthesized and investigated the obtained heterocycles by NMR techniques. In order to investigate the substituent effects on the spectroscopic properties, a series of indolizine derivatives were studied by 1 H-NMR, 13 C-NMR and 2D NMR (GCOSY, GHMBC and GHMQC spectra). (authors)

Structural characterization of chemical warfare agent degradation products in decontamination solutions with proton band-selective (1)H-(31)P NMR spectroscopy.

Science.gov (United States)

Koskela, Harri; Hakala, Ullastiina; Vanninen, Paula

2010-06-15

Decontamination solutions, which are usually composed of strong alkaline chemicals, are used for efficient detoxification of chemical warfare agents (CWAs). The analysis of CWA degradation products directly in decontamination solutions is challenging due to the nature of the matrix. Furthermore, occasionally an unforeseen degradation pathway can result in degradation products which could be eluded to in standard analyses. Here, we present the results of the application of proton band-selective (1)H-(31)P NMR spectroscopy, i.e., band-selective 1D (1)H-(31)P heteronuclear single quantum coherence (HSQC) and band-selective 2D (1)H-(31)P HSQC-total correlation spectroscopy (TOCSY), for ester side chain characterization of organophosphorus nerve agent degradation products in decontamination solutions. The viability of the approach is demonstrated with a test mixture of typical degradation products of nerve agents sarin, soman, and VX. The proton band-selective (1)H-(31)P NMR spectroscopy is also applied in characterization of unusual degradation products of VX in GDS 2000 solution.

Heteronuclear 2D NMR studies on an engineered insulin monomer: Assignments and characterization of the receptor-binding surface by selective 2H and 13C labeling with application to protein design

International Nuclear Information System (INIS)

Weiss, M.A.; Hua, Qingxin; Lynch, C.S.; Shoelson, S.E.; Frank, B.H.

1991-01-01

Insulin provides an important model for the application of genetic engineering to rational protein design and has been well characterized in the crystal state. However, self-association of insulin in solution has precluded complementary 2D NMR study under physiological conditions. The authors demonstrate here that such limitations may be circumvented by the use of a monomeric analogue that contains three amino acid substitutions on the protein surface (HisB10 → Asp, ProB28 → Lys, and LysB29 → Pro); this analogue (designated DKP-insulin) retains native receptor-binding potency. Comparative 1 H NMR studies of native human insulin and a series of three related analogues-(i) the singly substituted analogue [HisB10→Asp], (ii) the doubly substituted analogue [ProB28→Lys; LysB29→Pro], and (iii) DKP-insulin-demonstrate progressive reduction in concentration-dependent line-broadening in accord with the results of analytical ultracentrifugation. Extensive nonlocal interactions are observed in the NOESY spectrum of DKP-insulin, indicating that this analogue adopts a compact and stably folded structure as a monomer in overall accord with crystal models. Site-specific 2 H and 13 C isotopic labels are introduced by semisynthesis as probes for the structure and dynamics of the receptor-binding surface. These studies confirm and extend under physiological conditions the results of a previous 2D NMR analysis of native insulin in 20% acetic acid. Implications for the role of protein flexibility in receptor recognition are discussed with application to the design of novel insulin analogues

NMR studies of cerebral metabolism in vivo

International Nuclear Information System (INIS)

Prichard, J.W.

1986-01-01

The nature and extent of the potential synergism between PET and NMR methods is not yet well appreciated in the biomedical community. The long-range interest of medical neurobiology will be well served by efforts of PET and NMR scientists to follow each others' work so that opportunities for productive interchange can be efficiently exploited. Appreciation of the synergism by the rest of the biomedical community will follow naturally. PET is said by the people doing it to be still in its infancy, for they are more concerned with advancing their discipline than with admiring its already impressive achievements. On the scale of the same developmental metaphor, many NMR methods for studying the living human brain are still in utero. The best way to provide the reader a sense of the current status and future course of NMR research in medical neurobiology is by discussion of published in vivo studies. Such a discussion, adapted from another article is what follows

REDOR NMR of stable-isotope-labeled protein binding sites

Energy Technology Data Exchange (ETDEWEB)

Schaefer, J. [Washington Univ., St. Louis, MO (United States)

1994-12-01

Rotational-echo, double resonance (REDOR) NMR, a new analytical spectroscopic technique for solids spinning at the magic angle, has been developed over the last 5 years. REDOR provides a direct measure of heteronuclear dipolar coupling between isolated pairs of labeled nuclei. In a solid with a {sup 13}C-{sup 15}N labeled pair, for example, the {sup 13}C rotational echoes that form each rotor period following a{sup 1}H-{sup 13}C cross-polarization transfer can be prevented from reaching full intensity by insertion of a {sup 15}N {pi} pulse each half rotor period. The REDOR difference (the difference between a {sup 13}C NMR spectrum obtained under these conditions and one obtained with no {sup 15}N {pi} pulses) has a strong dependence on the {sup 13}C-{sup 15}N dipolar coupling, and hence, the {sup 13}C-{sup 15}N internuclear distance. REDOR is described as double-resonance even though three radio frequencies (typically {sup 1}H, {sup 13}C, and {sup 15}N) are used because the protons are removed from the important evolution part of the experiment by resonant decoupling. The dephasing of magnetization in REDOR arises from a local dipolar {sup 13}C-{sup 15}N field gradient and involves no polarization transfer. REDOR has no dependence on {sup 13}C or {sup 15}N chemical-shift tensors and does not require resolution of a {sup 13}C-{sup 15}N coupling in the chemical-shift dimension.

Further Study on Chemical Constituents of Parnassia wightiana Wall: Four New Dihydro-β-agarofuran Sesquiterpene Polyesters

Directory of Open Access Journals (Sweden)

Zhao-Feng Gao

2015-04-01

Full Text Available Four new (1–4, along with six known (5–10 dihydro-β-agarofuran sesquiterpene polyesters were isolated from the whole plants of Parnassia wightiana. The new compounds were structurally elucidated through spectroscopic analysis including UV (Ultraviolet Spectrum, IR (Infrared Spectrum, 1H-NMR (1Hydrogen-Nuclear Magnetic Resonance, 13C-NMR (13Carbon-Nuclear Magnetic Resonance, DEPT (Distortionless Enhancement by Polarization Transfer, 1H-1H COSY (1H-1H Correlation Spectroscopy, HSQC (Heteronuclear Single Quantum Coherence, HMBC (Heteronuclear Multiple Bond Correlation, NOESY (Nuclear Overhauser Enhancement Spectroscopy and HR-MS (High Resolution Mass Specttrum and their absolute configurations were proposed by comparison of NOESY spectra and specific optical rotations with those of known compounds and biosynthesis grounds. Compound 2 is the first sesquiterpene alkaloid isolated from this plant. New compounds 1–4 exhibited some cytotoxic activities against NB4, MKN-45 and MCF-7 cells at 20 μM and of which 4 showed the highest activity against NB4 and MKN-45 cells with inhibition rates of 85.6% and 30.5%, respectively.

Structural Studies of Biological Solids Using NMR

Science.gov (United States)

Ramamoorthy, Ayyalusamy

2011-03-01

High-resolution structure and dynamics of biological molecules are important in understanding their function. While studies have been successful in solving the structures of water-soluble biomolecules, it has been proven difficult to determine the structures of membrane proteins and fibril systems. Recent studies have shown that solid-state NMR is a promising technique and could be highly valuable in studying such non-crystalline and non-soluble biosystems. I will present strategies to study the structures of such challenging systems and also about the applications of solid-state NMR to study the modes of membrane-peptide interactions for a better assessment of the prospects of antimicrobial peptides as substitutes to antibiotics in the control of human disease. Our studies on the mechanism of membrane disruption by LL-37 (a human antimicrobial peptide), analogs of the naturally occurring antimicrobial peptide magainin2 extracted from the skin of the African frog Xenopus Laevis, and pardaxin will be presented. Solid-state NMR experiments were used to determine the secondary structure, dynamics and topology of these peptides in lipid bilayers. Similarities and difference in the cell-lysing mechanism, and their dependence on the membrane composition, of these peptides will be discussed. Atomic-level resolution NMR structures of amyloidogenic proteins revealing the misfolding pathway and early intermediates that play key roles in amyloid toxicity will also be presented.

NMR studies of the structure of glasses

International Nuclear Information System (INIS)

Bray, P.J.; Gravina, S.J.; Stallworth, P.E.; Szu, S.P.; Jianhui Zhong

1988-01-01

Earlier continuous wave (CW) NMR studies of chemical bonding and structure in glasses are summarized. Examples are given of this use of the quadrupolar interaction and chemical shift to obtain structural information. New NMR data and analyses are presented for alkali borate and gallate glasses. Extensions to other elements (e.g. molybdenum, lanthanum) are suggested. 44 refs. (author)

1H diffusion-weighted, 13C and 17O NMR spectroscopy: methodological developments to study brain structure and function in vivo

International Nuclear Information System (INIS)

Najac, Chloe

2014-01-01

Magnetic Resonance Spectroscopy is a unique tool that allows acquiring brain biochemical profiles and quantifying many cellular parameters in vivo. During this thesis, three different techniques have been developed: (i) 1 H diffusion-weighted, (ii) carbon-13 ( 13 C) and (iii) oxygen-17 ( 17 O) NMR spectroscopy to study brain structure and function in vivo. Brain metabolites are cell-specific endogenous tracers of the intracellular space whose translational diffusion depends on many cellular properties (e.g.: cytosol viscosity and intracellular restriction). Studying the variation of the diffusion coefficient (ADC) as a function of diffusion time (td) allows untangling and quantifying those parameters. In particular, measuring metabolites ADC at long diffusion times gives information about the metabolites compartmentation in cells. In a first study, we measured neuronal and astrocytic metabolites ADC over a large time window (from 80 ms to 1 s) in a large voxel in the macaque brain. No dependence of all metabolites ADC on td was observed suggesting that metabolites primarily diffuse in neuronal (dendrites and axons) and astrocytic processes and are not confined inside the cell body and organelles (nucleus, mitochondria). The large size of the voxel, due to low detection sensitivity, did not allow us to study metabolites compartmentation in pure white (WM) and grey matters (GM). Therefore, we performed a new study in the human brain. Results showed that in both WM and GM metabolites diffuse in fiber-like cell structure. Finally, using an even larger time window (up to 2 s) in the macaque brain and analytical models mimicking the cell structure, we estimated the length of neuronal (∼110 μm) and astrocytic (∼70 μm) processes. ATP (adenosine triphosphate), the main source of energy in the organism, is produced thanks to glucose oxidation inside the mitochondria. 13 C NMR spectroscopy is a well-known technique to study brain energy metabolism and can be used to

Characterization of threonine side chain dynamics in an antifreeze protein using natural abundance 13C NMR spectroscopy

International Nuclear Information System (INIS)

Daley, Margaret E.; Sykes, Brian D.

2004-01-01

The dynamics of threonine side chains of the Tenebrio molitor antifreeze protein (TmAFP) were investigated using natural abundance 13 C NMR. In TmAFP, the array of threonine residues on one face of the protein is responsible for conferring its ability to bind crystalline ice and inhibit its growth. Heteronuclear longitudinal and transverse relaxation rates and the 1 H- 13 C NOE were determined in this study. The CαH relaxation measurements were compared to the previously measured 15 N backbone parameters and these are found to be in agreement. For the analysis of the threonine side chain motions, the model of restricted rotational diffusion about the χ 1 dihedral angle was employed [London and Avitabile (1978) J. Am. Chem. Soc., 100, 7159-7165]. We demonstrate that the motion experienced by the ice binding threonine side chains is highly restricted, with an approximate upper limit of less than ±25 deg

Hydrogen and deuterium NMR of solids by magic-angle spinning

International Nuclear Information System (INIS)

Eckman, R.R.

1982-10-01

The nuclear magnetic resonance of solids has long been characterized by very large specral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, β/sub m/ = Arccos (3/sup -1/2/), with respect to the direction of the external magnetic field. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of β. A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H/sub D/ was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal motion. In the general case of large H/sub D/, isotropic spectra were obtained by dilution of 1 H with 2 H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids

Application of Solution NMR Spectroscopy to Study Protein Dynamics

Directory of Open Access Journals (Sweden)

Christoph Göbl

2012-03-01

Full Text Available Recent advances in spectroscopic methods allow the identification of minute fluctuations in a protein structure. These dynamic properties have been identified as keys to some biological processes. The consequences of this structural flexibility can be far‑reaching and they add a new dimension to the structure-function relationship of biomolecules. Nuclear Magnetic Resonance (NMR spectroscopy allows the study of structure as well as dynamics of biomolecules in a very broad range of timescales at atomic level. A number of new NMR methods have been developed recently to allow the measurements of time scales and spatial fluctuations, which in turn provide the thermodynamics associated with the biological processes. Since NMR parameters reflect ensemble measurements, structural ensemble approaches in analyzing NMR data have also been developed. These new methods in some instances can even highlight previously hidden conformational features of the biomolecules. In this review we describe several solution NMR methods to study protein dynamics and discuss their impact on important biological processes.

Simplifying the complex 1H NMR spectra of fluorine-substituted benzamides by spin system filtering and spin-state selection: multiple-quantum-single-quantum correlation.

Science.gov (United States)

Baishya, Bikash; Reddy, G N Manjunatha; Prabhu, Uday Ramesh; Row, T N Guru; Suryaprakash, N

2008-10-23

The proton NMR spectra of fluorine-substituted benzamides are very complex (Figure 1) due to severe overlap of (1)H resonances from the two aromatic rings, in addition to several short and long-range scalar couplings experienced by each proton. With no detectable scalar couplings between the inter-ring spins, the (1)H NMR spectra can be construed as an overlap of spectra from two independent phenyl rings. In the present study we demonstrate that it is possible to separate the individual spectrum for each aromatic ring by spin system filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spin-state selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes.

Characterization of threonine side chain dynamics in an antifreeze protein using natural abundance {sup 13}C NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Daley, Margaret E.; Sykes, Brian D. [University of Alberta, Department of Biochemistry, CIHR Group in Protein Structure and Function and Protein Engineering Network of Centres of Excellence (Canada)

2004-06-15

The dynamics of threonine side chains of the Tenebrio molitor antifreeze protein (TmAFP) were investigated using natural abundance {sup 13}C NMR. In TmAFP, the array of threonine residues on one face of the protein is responsible for conferring its ability to bind crystalline ice and inhibit its growth. Heteronuclear longitudinal and transverse relaxation rates and the {sup 1}H-{sup 13}C NOE were determined in this study. The C{alpha}H relaxation measurements were compared to the previously measured {sup 15}N backbone parameters and these are found to be in agreement. For the analysis of the threonine side chain motions, the model of restricted rotational diffusion about the {chi}{sub 1} dihedral angle was employed [London and Avitabile (1978) J. Am. Chem. Soc., 100, 7159-7165]. We demonstrate that the motion experienced by the ice binding threonine side chains is highly restricted, with an approximate upper limit of less than {+-}25 deg.

Protein folding on the ribosome studied using NMR spectroscopy

Science.gov (United States)

Waudby, Christopher A.; Launay, Hélène; Cabrita, Lisa D.; Christodoulou, John

2013-01-01

NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome–nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity. PMID:24083462

S³ HMBC hetero: Spin-State-Selective HMBC for accurate measurement of long-range heteronuclear coupling constants

DEFF Research Database (Denmark)

Hoeck, Casper; Gotfredsen, Charlotte Held; Sørensen, Ole W.

2017-01-01

A novel method, Spin-State-Selective (S3) HMBC hetero, for accurate measurement of heteronuclear coupling constants is introduced. The method extends the S3 HMBC technique for measurement of homonuclear coupling constants by appending a pulse sequence element that interchanges the polarization...

Study on the Effects of Oligo chitosan and Bioliquifert on Two Rice Mutants, NMR 151 and NMR 152

International Nuclear Information System (INIS)

Shakinah Salleh; Faiz Ahmad; Sobri Hussein

2016-01-01

Nuclear Malaysia has successfully developed two new rice mutants namely NMR 151 and NMR 152. In addition, Nuclear Malaysia has also successfully developed Oligo chitosan and liquid bio fertilizer (Bioliquifert). Oligo chitosan acts as elicitor that has been proven to be very effective in controlling disease infections and improving yield productivity. Bioliquifert on the other hand is a mixture of microbes containing major nutrient-providing microorganisms. The objective of this study is to observe the effects of Oligo chitosan and Bioliquifert on rice mutants, NMR 151 and NMR 152. The treatment was applied on 14 day old seedlings of MR 219, NMR 151 and NMR 152 sowed in 20 cm pots containing silty clay from the paddy soil of Tanjung Karang, Selangor. The seedlings were then placed in the greenhouse at Nuclear Malaysia until it reaches 110 days old. Study was conducted in a Complete Randomized Design (CRD) with 3 replications was used and each replication consisted of three plants. All treatments received compound and single dressing fertilizer as recommended by National Rice Production Package except for Treatment 2 and 3, in which Treatment 2 received Oligo chitosan and Bioliquifert while Treatment 3 only received Bioliquifert. Results on plant height, number of tiller and plant fresh weight are not significantly different for all cultivar except for seed dry weight of NMR 152 and MR 219. (author)

NMR-Metabolic Methodology in the Study of GM Foods

Science.gov (United States)

The 1H NMR methodology used in the study of genetically modified (GM) foodstuff is discussed. The study of transgenic lettuce (Lactuca sativa cv "Luxor") over-expressing the KNAT1 gene from Arabidopsis is presented as a novel study-case. The 1H NMR metabolic profiling was carried out. Twenty-two wat...

(13)C heteronuclear NMR studies of the interaction of cultured neurons and astrocytes and aluminum blockade of the preferential release of citrate from astrocytes.

Science.gov (United States)

Meshitsuka, Shunsuke; Aremu, David A

2008-02-01

Citrate has been identified as a major tricarboxylic acid (TCA) cycle constituent preferentially released by astrocytes. We undertook the present study to examine further the nature of metabolic compartmentation in central nervous system tissues using (13)C-labeled glucose and to provide new information on the influence of aluminum on the metabolic interaction between neurons and astrocytes. Metabolites released into the culture medium from astrocytes and neuron-astrocyte coculture, as well as the perchloric acid extracts of the cells were analyzed using 2D (1)H and (13)C NMR spectroscopy. Astrocytes released citrate into the culture medium and the released citrate was consumed by neurons in coculture. Citrate release by astrocytes was blocked in the presence of aluminum, with progressive accumulation of citrate within the cells. We propose citrate supply is a more efficient energy source than lactate for neurons to produce ATP, especially in the hypoglycemic state on account of it being a direct component of the TCA cycle. Astrocytes may be the cellular compartment for aluminum accumulation as a citrate complex in the brain.

Measurement and Characterization of Hydrogen-Deuterium Exchange Chemistry Using Relaxation Dispersion NMR Spectroscopy.

Science.gov (United States)

Khirich, Gennady; Holliday, Michael J; Lin, Jasper C; Nandy, Aditya

2018-03-01

One-dimensional heteronuclear relaxation dispersion NMR spectroscopy at 13 C natural abundance successfully characterized the dynamics of the hydrogen-deuterium exchange reaction occurring at the N ε position in l-arginine by monitoring C δ in varying amounts of D 2 O. A small equilibrium isotope effect was observed and quantified, corresponding to ΔG = -0.14 kcal mol -1 . A bimolecular rate constant of k D = 5.1 × 10 9 s -1 M -1 was determined from the pH*-dependence of k ex (where pH* is the direct electrode reading of pH in 10% D 2 O and k ex is the nuclear spin exchange rate constant), consistent with diffusion-controlled kinetics. The measurement of ΔG serves to bridge the millisecond time scale lifetimes of the detectable positively charged arginine species with the nanosecond time scale lifetime of the nonobservable low-populated neutral arginine intermediate species, thus allowing for characterization of the equilibrium lifetimes of the various arginine species in solution as a function of fractional solvent deuterium content. Despite the system being in fast exchange on the chemical shift time scale, the magnitude of the secondary isotope shift due to the exchange reaction at N ε was accurately measured to be 0.12 ppm directly from curve-fitting D 2 O-dependent dispersion data collected at a single static field strength. These results indicate that relaxation dispersion NMR spectroscopy is a robust and general method for studying base-catalyzed hydrogen-deuterium exchange chemistry at equilibrium.

Metabolite characterization in serum samples from normal healthy ...

African Journals Online (AJOL)

Metabolite characterization in serum samples from normal healthy human subjects by 1H and 13C NMR spectroscopy. D Misra, U Bajpai. Abstract. One and two dimensional NMR spectroscopy has been employed to characterize the various metabolites of serum control healthy samples. Two dimensional heteronuclear ...

Fine hierarchy of the V-O bonds by advanced solid state NMR: novel Pb4(VO2)(PO4)3 structure as a textbook case.

Science.gov (United States)

Tricot, Grégory; Mentré, Olivier; Cristol, Sylvain; Delevoye, Laurent

2012-12-17

We report here a complete structural characterization of a new lead Pb(4)(VO(2))(PO(4))(3) vanadophosphate compound by single crystal X-ray diffraction and (51)V and (31)P solid-state NMR spectroscopy. Although structural data are commonly used for the estimation of bond lengths and further delimitation of the true coordination number (e.g., octahedral: 6 versus 5 + 1 versus 4 + 2), we show here for the first time by solid-state NMR a more accurate appreciation of the V-O bonding scheme in this complex oxide which appears well adapted to the full series of vanado-phosphate materials. The direct characterization of V-O-P bridges through the J-mediated correlation (51)V{(31)P} heteronuclear multiple quantum coherence (J-HMQC) technique allows a contrasted hierarchy of the V-O electronic delocalization and indirectly supports the presence or not of the V-O bond. In the reported lead vanado-phosphate structure, the two vanadium polyhedra that have been assigned to octahedra from a bond length point of view have been finally reclassified as tetra- and penta-coordinated units on the basis of the solid-state NMR results. More generally, we believe that the improved characterization of interatomic bonds in various vanado-phosphate structures by solid-state NMR will contribute to a better understanding of the structure/property relationships in this important class of materials.

Real-time Kinetics of High-mobility Group Box 1 (HMGB1) Oxidation in Extracellular Fluids Studied by in Situ Protein NMR Spectroscopy*

Science.gov (United States)

Zandarashvili, Levani; Sahu, Debashish; Lee, Kwanbok; Lee, Yong Sun; Singh, Pomila; Rajarathnam, Krishna; Iwahara, Junji

2013-01-01

Some extracellular proteins are initially secreted in reduced forms via a non-canonical pathway bypassing the endoplasmic reticulum and become oxidized in the extracellular space. One such protein is HMGB1 (high-mobility group box 1). Extracellular HMGB1 has different redox states that play distinct roles in inflammation. Using a unique NMR-based approach, we have investigated the kinetics of HMGB1 oxidation and the half-lives of all-thiol and disulfide HMGB1 species in serum, saliva, and cell culture medium. In this approach, salt-free lyophilized 15N-labeled all-thiol HMGB1 was dissolved in actual extracellular fluids, and the oxidation and clearance kinetics were monitored in situ by recording a series of heteronuclear 1H-15N correlation spectra. We found that the half-life depends significantly on the extracellular environment. For example, the half-life of all-thiol HMGB1 ranged from ∼17 min (in human serum and saliva) to 3 h (in prostate cancer cell culture medium). Furthermore, the binding of ligands (glycyrrhizin and heparin) to HMGB1 significantly modulated the oxidation kinetics. Thus, the balance between the roles of all-thiol and disulfide HMGB1 proteins depends significantly on the extracellular environment and can also be artificially modulated by ligands. This is important because extracellular HMGB1 has been suggested as a therapeutic target for inflammatory diseases and cancer. Our work demonstrates that the in situ protein NMR approach is powerful for investigating the behavior of proteins in actual extracellular fluids containing an enormous number of different molecules. PMID:23447529

NMR imaging studies of coal

Energy Technology Data Exchange (ETDEWEB)

Ma, Z.R.; Zhang, P.Z.; Ding, G.L.; Li, L.Y.; Ye, C.H. [University of Science and Technology, Beijing (China). Dept. of Chemistry

1996-06-01

The permeation transportation and swelling behavior of solvents into coal are investigated by NMR imaging using pyridine-d{sub 5} and acetone-d{sub 6}. Images of coal swollen with deuterated solvents illuminate proton distributions of mobile phases within the coal macromolecular networks. More information about the chemical and physical structure of coal can be obtained using NMR imaging techniques.

NMR study of Albemoschus esculentus characterization

International Nuclear Information System (INIS)

Bathista, A.L.B.S; Silva, E.O.; Nogueira, Jose de S.; Tavares, M.I.B.

2001-01-01

The investigation of the main compounds presented in the Albemoschus esculentus has been carried out employing nuclear magnetic resonance spectroscopy (NMR), using solution and solid state NMR when it one was necessary. The evaluation of NMR data allowed us to characterize the main type of components presented in this kind of sample. It was necessary to use a total information from solid state NMR and also the solution response. From these information we could get that four main components were presented in this sample. One in the shell, that is cellulose, another one between the shell and seeds that is a polysaccharide and in the seed two components were found one is a starch and the second one is an oil, a triacylglycerol. These components are responsible by its physical chemistry properties. (author)

NMR studies of metallic tin confined within porous matrices

International Nuclear Information System (INIS)

Charnaya, E. V.; Tien, Cheng; Lee, M. K.; Kumzerov, Yu. A.

2007-01-01

119 Sn NMR studies were carried out for metallic tin confined within synthetic opal and porous glass. Tin was embedded into nanoporous matrices in the melted state under pressure. The Knight shift for liquid confined tin was found to decrease with decreasing pore size. Correlations between NMR line shapes, Knight shift, and pore filling were observed. The melting and freezing phase transitions of tin under confinement were studied through temperature dependences of NMR signals upon warming and cooling. Melting of tin within the opal matrix agreed well with the liquid skin model suggested for small isolated particles. The influence of the pore filling on the melting process was shown

Simulations of NMR pulse sequences during equilibrium and non-equilibrium chemical exchange

International Nuclear Information System (INIS)

Helgstrand, Magnus; Haerd, Torleif; Allard, Peter

2000-01-01

The McConnell equations combine the differential equations for a simple two-state chemical exchange process with the Bloch differential equations for a classical description of the behavior of nuclear spins in a magnetic field. This equation system provides a useful starting point for the analysis of slow, intermediate and fast chemical exchange studied using a variety of NMR experiments. The McConnell equations are in the mathematical form of an inhomogeneous system of first-order differential equations. Here we rewrite the McConnell equations in a homogeneous form in order to facilitate fast and simple numerical calculation of the solution to the equation system. The McConnell equations can only treat equilibrium chemical exchange. We therefore also present a homogeneous equation system that can handle both equilibrium and non-equilibrium chemical processes correctly, as long as the kinetics is of first-order. Finally, the same method of rewriting the inhomogeneous form of the McConnell equations into a homogeneous form is applied to a quantum mechanical treatment of a spin system in chemical exchange. In order to illustrate the homogeneous McConnell equations, we have simulated pulse sequences useful for measuring exchange rates in slow, intermediate and fast chemical exchange processes. A stopped-flow NMR experiment was simulated using the equations for non-equilibrium chemical exchange. The quantum mechanical treatment was tested by the simulation of a sensitivity enhanced 15 N-HSQC with pulsed field gradients during slow chemical exchange and by the simulation of the transfer efficiency of a two-dimensional heteronuclear cross-polarization based experiment as a function of both chemical shift difference and exchange rate constants

Synthesis and magnetic properties of heteronuclear 3d-4f compound

International Nuclear Information System (INIS)

Cristovao, B.; Ferenc, W.

2007-01-01

A novel heteronuclear 3d-4f compound having formula NdCu 3 L 3 ·13H 2 O (where H 3 L = Schiff base derived from 5-bromosalicylaldehyde and glycylglycine and L 3 = C 11 H 8 N 2 O 4 Br) was obtained. It was characterized by elemental and thermal analyses and magnetic measurements. The Cu(II)-Nd(III) compound is stable up to 323 K. During dehydration process the water molecules are lost in two stages. The magnetic susceptibility data for this complex change with temperature according to the Curie-Weiss law with Θ = -35 K. The magnetic moment values decrease from 5.00μ B at 303 K to 4.38μB at 76 K. (author)

DNA oligonucleotide conformations: high resolution NMR studies

International Nuclear Information System (INIS)

Mellema, J.-R.

1984-01-01

The present work describes a DNA double-helix model, which is well comparable with the models derived from fibre-diffraction studies. The model has a mononucleotide repeat with torsion angles in accordance with average geometries as derived from 1 H NMR studies. Special attention was paid to reduce the number of short H-H nonbonding contacts, which are abundantly present in the 'classical' fibre-diffraction models. Chapter 3 describes the first complete assignment of a 1 H NMR spectrum of a DNA tetramer, d(TAAT). Preliminary conformational data derived from the spectral parameters recorded at 27 0 C are given. A more detailed analysis employing temperature-dependence studies is given in Chapter 4. (Auth.)

Microbial transformation of Isopimpinellin by Glomerella cingulata.

Science.gov (United States)

Marumoto, Shinsuke; Miyazawa, Mitsuo

2011-01-01

Microbial transformation studies conducted on isopimpinellin (1) by the fungus Glomerella cingulata have revealed that 1 was metabolized to give the corresponding reduced acid, 5,8-dimethoxy-6,7-furano-hydrocoumaric acid (2). The structure of metabolite 2 was elucidated by high-resolution mass spectrometry (HR-MS), extensive NMR techniques, including (1)H NMR, (13)C NMR, (1)H-(1)H correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC) and heteonuclear multiple bond coherence (HMBC). The biotransformed product 2 showed weak a in vitro β-secretase (BACE1) inhibitory effect.

Surface Properties of Squalene/Meibum Films and NMR Confirmation of Squalene in Tears

Directory of Open Access Journals (Sweden)

Slavyana Ivanova

2015-09-01

Full Text Available Squalene (SQ possesses a wide range of pharmacological activities (antioxidant, drug carrier, detoxifier, hydrating, emollient that can be of benefit to the ocular surface. It can come in contact with human meibum (hMGS; the most abundant component of the tear film lipid layer as an endogenous tear lipid or from exogenous sources as eyelid sebum or pharmaceuticals. The aims of this study were to determine (i if SQ is in tear lipids and (ii its influence on the surface properties of hMGS films. Heteronuclear single quantum correlation NMR confirmed 7 mol % SQ in Schirmer’s strips extracts. The properties of SQ/hMGS pseudo-binary films at the air/water interface were studied with Langmuir surface balance, stress-relaxation dilatational rheology and Brewster angle microscopy. SQ does not possess surfactant properties. When mixed with hMGS squalene (i localized over the layers’ thinner regions and (ii did not affect the film pressure at high compression. Therefore, tear SQ is unlikely to instigate dry eye, and SQ can be used as a safe and “inert” ingredient in formulations to protect against dry eye. The layering of SQ over the thinner film regions in addition to its pharmacological properties could contribute to the protection of the ocular surface.

NMR-Metabolic Methodology in the Study of GM Foods

Directory of Open Access Journals (Sweden)

Irene D’Amico

2010-01-01

Full Text Available The 1H-NMR methodology used in the study of genetically modified (GM foods is discussed. Transgenic lettuce (Lactuca sativa cv "Luxor" over-expressing the Arabidopsis KNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars present in leaves of conventional and GM lettuce were monitored by NMR and quantified at two developmental stages. The NMR spectra did not reveal any difference in metabolite composition between the GM lettuce and the wild type counterpart. Statistical analyses of metabolite variables highlighted metabolism variation as a function of leaf development as well as the transgene. A main effect of the transgene was in altering sugar metabolism.

Interpretation of NMR relaxation properties of Pin1, a two-domain protein, based on Brownian dynamic simulations

International Nuclear Information System (INIS)

Bernado, Pau; Fernandes, Miguel X.; Jacobs, Doris M.; Fiebig, Klaus; Garcia de la Torre, Jose; Pons, Miquel

2004-01-01

Many important proteins contain multiple domains connected by flexible linkers. Inter-domain motion is suggested to play a key role in many processes involving molecular recognition. Heteronuclear NMR relaxation is sensitive to motions in the relevant time scales and could provide valuable information on the dynamics of multi-domain proteins. However, the standard analysis based on the separation of global tumbling and fast local motions is no longer valid for multi-domain proteins undergoing internal motions involving complete domains and that take place on the same time scale than the overall motion.The complexity of the motions experienced even for the simplest two-domain proteins are difficult to capture with simple extensions of the classical Lipari-Szabo approach. Hydrodynamic effects are expected to dominate the motion of the individual globular domains, as well as that of the complete protein. Using Pin1 as a test case, we have simulated its motion at the microsecond time scale, at a reasonable computational expense, using Brownian Dynamic simulations on simplified models. The resulting trajectories provide insight on the interplay between global and inter-domain motion and can be analyzed using the recently published method of isotropic Reorientational Mode Dynamics which offer a way of calculating their contribution to heteronuclear relaxation rates. The analysis of trajectories computed with Pin1 models of different flexibility provides a general framework to understand the dynamics of multi-domain proteins and explains some of the observed features in the relaxation rate profile of free Pin1

Interpretation of NMR relaxation properties of Pin1, a two-domain protein, based on Brownian dynamic simulations

Energy Technology Data Exchange (ETDEWEB)

Bernado, Pau [Institut de Biologie Structurale, Jean Pierre Ebel (France); Fernandes, Miguel X. [Universidad de Murcia, Departamento de Quimica Fisica, Facultad de Quimica (Spain); Jacobs, Doris M. [Johann Wolfgang Goethe-Universitaet Frankfurt, Institut fuer Organische Chemie und Chemische Biologie (Germany); Fiebig, Klaus [Affinium Pharmaceuticals (Canada); Garcia de la Torre, Jose [Universidad de Murcia, Departamento de Quimica Fisica, Facultad de Quimica (Spain); Pons, Miquel [Laboratori de RMN de Biomolecules, Parc Cientific de Barcelona (Spain)], E-mail: mpons@ub.edu

2004-05-15

Many important proteins contain multiple domains connected by flexible linkers. Inter-domain motion is suggested to play a key role in many processes involving molecular recognition. Heteronuclear NMR relaxation is sensitive to motions in the relevant time scales and could provide valuable information on the dynamics of multi-domain proteins. However, the standard analysis based on the separation of global tumbling and fast local motions is no longer valid for multi-domain proteins undergoing internal motions involving complete domains and that take place on the same time scale than the overall motion.The complexity of the motions experienced even for the simplest two-domain proteins are difficult to capture with simple extensions of the classical Lipari-Szabo approach. Hydrodynamic effects are expected to dominate the motion of the individual globular domains, as well as that of the complete protein. Using Pin1 as a test case, we have simulated its motion at the microsecond time scale, at a reasonable computational expense, using Brownian Dynamic simulations on simplified models. The resulting trajectories provide insight on the interplay between global and inter-domain motion and can be analyzed using the recently published method of isotropic Reorientational Mode Dynamics which offer a way of calculating their contribution to heteronuclear relaxation rates. The analysis of trajectories computed with Pin1 models of different flexibility provides a general framework to understand the dynamics of multi-domain proteins and explains some of the observed features in the relaxation rate profile of free Pin1.

Simultaneous acquisition of 2D and 3D solid-state NMR experiments for sequential assignment of oriented membrane protein samples

Energy Technology Data Exchange (ETDEWEB)

Gopinath, T. [University of Minnesota, Department of Biochemistry, Molecular Biology, and Biophysics (United States); Mote, Kaustubh R. [University of Minnesota, Department of Chemistry (United States); Veglia, Gianluigi, E-mail: vegli001@umn.edu [University of Minnesota, Department of Biochemistry, Molecular Biology, and Biophysics (United States)

2015-05-15

We present a new method called DAISY (Dual Acquisition orIented ssNMR spectroScopY) for the simultaneous acquisition of 2D and 3D oriented solid-state NMR experiments for membrane proteins reconstituted in mechanically or magnetically aligned lipid bilayers. DAISY utilizes dual acquisition of sine and cosine dipolar or chemical shift coherences and long living {sup 15}N longitudinal polarization to obtain two multi-dimensional spectra, simultaneously. In these new experiments, the first acquisition gives the polarization inversion spin exchange at the magic angle (PISEMA) or heteronuclear correlation (HETCOR) spectra, the second acquisition gives PISEMA-mixing or HETCOR-mixing spectra, where the mixing element enables inter-residue correlations through {sup 15}N–{sup 15}N homonuclear polarization transfer. The analysis of the two 2D spectra (first and second acquisitions) enables one to distinguish {sup 15}N–{sup 15}N inter-residue correlations for sequential assignment of membrane proteins. DAISY can be implemented in 3D experiments that include the polarization inversion spin exchange at magic angle via I spin coherence (PISEMAI) sequence, as we show for the simultaneous acquisition of 3D PISEMAI–HETCOR and 3D PISEMAI–HETCOR-mixing experiments.

Simultaneous acquisition of 2D and 3D solid-state NMR experiments for sequential assignment of oriented membrane protein samples.

Science.gov (United States)

Gopinath, T; Mote, Kaustubh R; Veglia, Gianluigi

2015-05-01

We present a new method called DAISY (Dual Acquisition orIented ssNMR spectroScopY) for the simultaneous acquisition of 2D and 3D oriented solid-state NMR experiments for membrane proteins reconstituted in mechanically or magnetically aligned lipid bilayers. DAISY utilizes dual acquisition of sine and cosine dipolar or chemical shift coherences and long living (15)N longitudinal polarization to obtain two multi-dimensional spectra, simultaneously. In these new experiments, the first acquisition gives the polarization inversion spin exchange at the magic angle (PISEMA) or heteronuclear correlation (HETCOR) spectra, the second acquisition gives PISEMA-mixing or HETCOR-mixing spectra, where the mixing element enables inter-residue correlations through (15)N-(15)N homonuclear polarization transfer. The analysis of the two 2D spectra (first and second acquisitions) enables one to distinguish (15)N-(15)N inter-residue correlations for sequential assignment of membrane proteins. DAISY can be implemented in 3D experiments that include the polarization inversion spin exchange at magic angle via I spin coherence (PISEMAI) sequence, as we show for the simultaneous acquisition of 3D PISEMAI-HETCOR and 3D PISEMAI-HETCOR-mixing experiments.

Simultaneous acquisition of 2D and 3D solid-state NMR experiments for sequential assignment of oriented membrane protein samples

International Nuclear Information System (INIS)

Gopinath, T.; Mote, Kaustubh R.; Veglia, Gianluigi

2015-01-01

We present a new method called DAISY (Dual Acquisition orIented ssNMR spectroScopY) for the simultaneous acquisition of 2D and 3D oriented solid-state NMR experiments for membrane proteins reconstituted in mechanically or magnetically aligned lipid bilayers. DAISY utilizes dual acquisition of sine and cosine dipolar or chemical shift coherences and long living 15 N longitudinal polarization to obtain two multi-dimensional spectra, simultaneously. In these new experiments, the first acquisition gives the polarization inversion spin exchange at the magic angle (PISEMA) or heteronuclear correlation (HETCOR) spectra, the second acquisition gives PISEMA-mixing or HETCOR-mixing spectra, where the mixing element enables inter-residue correlations through 15 N– 15 N homonuclear polarization transfer. The analysis of the two 2D spectra (first and second acquisitions) enables one to distinguish 15 N– 15 N inter-residue correlations for sequential assignment of membrane proteins. DAISY can be implemented in 3D experiments that include the polarization inversion spin exchange at magic angle via I spin coherence (PISEMAI) sequence, as we show for the simultaneous acquisition of 3D PISEMAI–HETCOR and 3D PISEMAI–HETCOR-mixing experiments

A pulse programmable parahydrogen polarizer using a tunable electromagnet and dual channel NMR spectrometer

Science.gov (United States)

Coffey, Aaron M.; Shchepin, Roman V.; Feng, Bibo; Colon, Raul D.; Wilkens, Ken; Waddell, Kevin W.; Chekmenev, Eduard Y.

2017-11-01

Applications of parahydrogen induced polarization (PHIP) often warrant conversion of the chemically-synthesized singlet-state spin order into net heteronuclear magnetization. In order to obtain optimal yields from the overall hyperpolarization process, catalytic hydrogenation must be tightly synchronized to subsequent radiofrequency (RF) transformations of spin order. Commercial NMR consoles are designed to synchronize applied waves on multiple channels and consequently are well-suited as controllers for these types of hyperpolarization experiments that require tight coordination of RF and non-RF events. Described here is a PHIP instrument interfaced to a portable NMR console operating with a static field electromagnet in the milliTesla regime. In addition to providing comprehensive control over chemistry and RF events, this setup condenses the PHIP protocol into a pulse-program that in turn can be readily shared in the manner of traditional pulse sequences. In this device, a TTL multiplexer was constructed to convert spectrometer TTL outputs into 24 VDC signals. These signals then activated solenoid valves to control chemical shuttling and reactivity in PHIP experiments. Consolidating these steps in a pulse-programming environment speeded calibration and improved quality assurance by enabling the B0/B1 fields to be tuned based on the direct acquisition of thermally polarized and hyperpolarized NMR signals. Performance was tested on the parahydrogen addition product of 2-hydroxyethyl propionate-1-13C-d3, where the 13C polarization was estimated to be P13C = 20 ± 2.5% corresponding to 13C signal enhancement approximately 25 million-fold at 9.1 mT or approximately 77,000-fold 13C enhancement at 3 T with respect to thermally induced polarization at room temperature.

NMR study of LaPb2

International Nuclear Information System (INIS)

Ueda, K.; Kohara, T.; Yamada, Y.

1995-01-01

La and Pb NMR signals were observed in LaPb 2 with a superconducting transition temperature of about 7 K. The width of the Pb NMR spectrum with an asymmetric line shape was rather narrower than those of Er-, Gd- and Ho-Pb 2 . The spin-lattice relaxation time of Pb nuclei was twice longer than that of Pb metal. La NMR spectrum had satellites due to the electric quadrupole interaction. These results show that each local environment at La or Pb site in LaPb 2 compound is uniquely determined, compared with those in randomly substituted alloys. ((orig.))

Observation of Resonant Effects in Ultracold Collisions between Heteronuclear Feshbach Molecules

Science.gov (United States)

Ye, Xin; Wang, Fudong; Zhu, Bing; Guo, Mingyang; Lu, Bo; Wang, Dajun

2016-05-01

Magnetic field dependent dimer-dimer collisional losses are studied with ultracold 23 Na87 Rb Feshbach molecules. By ramping the magnetic field across the 347.8 G inter-species Feshbach resonance and removing residual atoms with a magnetic field gradient, ~ 8000 pure NaRb Feshbach molecules with a temperature below 1 μK are produced. By holding the pure molecule sample in a crossed optical dipole trap and measuring the time-dependent loss curves under different magnetic fields near the Feshbach resonance, the dimer-dimer loss rates with respect to the atomic scattering length a are mapped out. We observe a resonant feature at around a = 600a0 and a rising tail at above a = 1600a0 . This behavior resembles previous theoretical works on homonuclear Feshbach molecule, where resonant effects between dimer-dimer collisions tied to tetramer bound states were predicted. Our work shows the possibility of exploring four-body physics within a heteronuclear system. We are supported by Hong Kong RGC General Research Fund no. CUHK403813.

1H and 15N resonance assignments of oxidized flavodoxin from Anacystis nidulans with 3D NMR

International Nuclear Information System (INIS)

Clubb, R.T.; Thanabal, V.; Wagner, G.; Osborne, C.

1991-01-01

Proton and nitrogen-15 sequence-specific nuclear magnetic resonance assignments have been determined for recombinant oxidized flavodoxin from Anacystis nidulans. Assignments were obtained by using 15 N- 1 H heteronuclear three-dimensional (3D) NMR spectroscopy on a uniformly nitrogen-15 enriched sample of the protein, pH 6.6, at 30C. For 165 residues, the backbone and a large fraction of the side-chain proton resonances have been assigned. Medium- and long-range NOE's have been used to characterize the secondary structure. In solution, flavodoxin consists of a five-stranded parallel β sheet involving residues 3-9, 31-37, 49-56, 81-89, 114-117, and 141-144. Medium-range NOE's indicate that presence of several helices. Several 15 N and 1 H resonances of the flavin mononucleotide (FMN) prosthetic group have been assigned. The FMN-binding site has been investigated by using polypeptide-FMN NOE's

Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

Science.gov (United States)

Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike; Auken, Esben; Barfod, Adrian A. S.; Ferré, Ty P. A.; Vilhelmsen, Troels N.; Johnson, Carole D.; Christiansen, Anders V.

2017-11-01

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.

A comparative study of bone scintigraphy and NMR for vertebral diseases

International Nuclear Information System (INIS)

Nakatani, Mariko; Sekiya, Toru; Hata, Yuichi; Mori, Yutaka; Yasuda, Masanobu; Kawakami, Kenji; Tada, Sinpei

1985-01-01

A comparative study of NMR and bone scintigraphy was performed in vertebral disorders, and the significance of both modalities was evaluated. Twelve patients with various vertebral abnormalities including ten cases of vertebral metastases, one case of cervical caries and one case of Granular cell tumor of L3, were examined. In 4 patients, NMR showed abnormalities in the same regions as the bone scintigrams. In another 3 patients. NMR did not show the disorders reported on bone scintigrams. This may be due to the low NMR sensitivity to tiny infiltration of tumor cells in the bone marrow. In 3 out of the remaining 5 patients, NMR demonstrated abnormal findings, whilst the bone scintigrams were normal. Previous bone scintigrams in these patients before treatment had shown abnormal accumulation of activity in the region of abnormal NMR findings. This may be due to the fact that NMR detects the irreversible change of bone marrow, and bone scintigram demonstrates the turn over of bone minerals. This limited experience suggests that both madalities are complementary in the evaluation of vertebral abnormalities. (author)

Rhodopsin-lipid interactions studied by NMR.

Science.gov (United States)

Soubias, Olivier; Gawrisch, Klaus

2013-01-01

The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200-nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60μm yields on the order of 500cm(2) of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated, and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By (2)H NMR order parameter measurements, it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by (1)H saturation-transfer NMR under conditions of magic angle spinning, we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. Copyright © 2013 Elsevier Inc. All rights reserved.

Intramolecular hydrogen bonding and tautomerism in Schiff bases ...

Indian Academy of Sciences (India)

Administrator

C NMR, DEPT and aided by 2D HETCOR and HMBC heteronuclear correlation techniques. The UV-vis spectra of the Schiff bases have been systematically studied in organic solvents of different polarity, acidic and basic media and found useful in understanding of tautomeric equilibria (phenol-imine, O–H...N and ...

Hyperpolarized 129Xe as an NMR probe for functional studies

International Nuclear Information System (INIS)

Wolber, J.

2000-01-01

The nuclear spin polarization of 129 Xe can be enhanced by several orders of magnitude using optical pumping techniques, resulting in a dramatic enhancement of the 129 Xe Nuclear Magnetic Resonance (NMR) signal. The 'hyperpolarized' gas can be used for Magnetic Resonance Imaging (MRI) of the void spaces of the lungs after introduction of the gas into the respiratory system. Furthermore, the high solubility of xenon in blood and lipids suggests the use of 129 Xe NMR for studying blood flow, permeability, perfusion and blood volume. Hyperpolarized 129 Xe MRI has the potential of combining the high sensitivity and functional information of radioactive tracer studies with the high spatial and temporal resolution of MRI. The spin-lattice relaxation time T 1 of 129 Xe in blood determines the loss of polarization during transit from the lungs to the tissue of interest. A difference in the relaxation times of xenon in oxygenated and deoxygenated blood could be used as a contrast mechanism in functional Magnetic Resonance Imaging (fMRI). In this thesis, the hyperpolarized 129 Xe T 1 in human blood is measured in vitro as a function of blood oxygenation, and the relevant relaxation mechanisms are discussed. A new and unexpected finding is that the hyperpolarized 129 Xe NMR spectrum in blood is highly sensitive to blood oxygenation. Therefore, hyperpolarized 129 Xe NMR provides a powerful means of measuring blood oxygenation quantitatively and non-invasively. The interaction of xenon with hemoglobin is responsible for an oxygen-dependent shift of the 129 Xe NMR resonance of xenon in red blood cells. Injection delivery of hyperpolarized 129 Xe in solution could be a more efficient method of administrating the gas for functional NMR studies. For this purpose, suitable biocompatible carrier media have been studied. In particular, the use of perfluorocarbon emulsions, which are already in use as blood substitutes, as delivery media for hyperpolarized 129 Xe has been investigates

Proton NMR studies of functionalized nanoparticles in aqueous environments

Science.gov (United States)

Tataurova, Yulia Nikolaevna

Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results

Trifasciatosides A-J, Steroidal Saponins from Sansevieria trifasciata.

Science.gov (United States)

Teponno, Rémy Bertrand; Tanaka, Chiaki; Jie, Bai; Tapondjou, Léon Azefack; Miyamoto, Tomofumi

2016-01-01

Four previously unreported steroidal saponins, trifasciatosides A-D (1-4), three pairs of previously undescribed steroidal saponins, trifasciatosides E-J (5a, b-7a, b) including acetylated ones, together with twelve known compounds were isolated from the n-butanol soluble fraction of the methanol extract of Sansevieria trifasciata. Their structures were elucidated on the basis of detailed spectroscopic analysis, including (1)H-NMR, (13)C-NMR, (1)H-(1)H correlated spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC), total correlated spectroscopy (TOCSY), nuclear Overhauser enhancement and exchange spectroscopy (NOESY), electrospray ionization-time of flight (ESI-TOF)-MS and chemical methods. Compounds 2, 4, and 7a, b exhibited moderate antiproliferative activity against HeLa cells.

Activation and thermodynamic parameter study of the heteronuclear C=O···H-N hydrogen bonding of diphenylurethane isomeric structures by FT-IR spectroscopy using the regularized inversion of an eigenvalue problem.

Science.gov (United States)

Spegazzini, Nicolas; Siesler, Heinz W; Ozaki, Yukihiro

2012-08-02

The doublet of the ν(C=O) carbonyl band in isomeric urethane systems has been extensively discussed in qualitative terms on the basis of FT-IR spectroscopy of the macromolecular structures. Recently, a reaction extent model was proposed as an inverse kinetic problem for the synthesis of diphenylurethane for which hydrogen-bonded and non-hydrogen-bonded C=O functionalities were identified. In this article, the heteronuclear C=O···H-N hydrogen bonding in the isomeric structure of diphenylurethane synthesized from phenylisocyanate and phenol was investigated via FT-IR spectroscopy, using a methodology of regularization for the inverse reaction extent model through an eigenvalue problem. The kinetic and thermodynamic parameters of this system were derived directly from the spectroscopic data. The activation and thermodynamic parameters of the isomeric structures of diphenylurethane linked through a hydrogen bonding equilibrium were studied. The study determined the enthalpy (ΔH = 15.25 kJ/mol), entropy (TΔS = 14.61 kJ/mol), and free energy (ΔG = 0.6 kJ/mol) of heteronuclear C=O···H-N hydrogen bonding by FT-IR spectroscopy through direct calculation from the differences in the kinetic parameters (δΔ(‡)H, -TδΔ(‡)S, and δΔ(‡)G) at equilibrium in the chemical reaction system. The parameters obtained in this study may contribute toward a better understanding of the properties of, and interactions in, supramolecular systems, such as the switching behavior of hydrogen bonding.

NMR and optical studies of piezoelectric polymers

International Nuclear Information System (INIS)

Schmidt, V.H.; Tuthill, G.F.

1993-01-01

Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF 2 ) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done

Understanding API-polymer proximities in amorphous stabilized composite drug products using fluorine-carbon 2D HETCOR solid-state NMR.

Science.gov (United States)

Abraham, Anuji; Crull, George

2014-10-06

A simple and robust method for obtaining fluorine-carbon proximities was established using a (19)F-(13)C heteronuclear correlation (HETCOR) two-dimensional (2D) solid-state nuclear magnetic resonance (ssNMR) experiment under magic-angle spinning (MAS). The method was applied to study a crystalline active pharmaceutical ingredient (API), avagacestat, containing two types of fluorine atoms and its API-polymer composite drug product. These results provide insight into the molecular structure, aid with assigning the carbon resonances, and probe API-polymer proximities in amorphous spray dried dispersions (SDD). This method has an advantage over the commonly used (1)H-(13)C HETCOR because of the large chemical shift dispersion in the fluorine dimension. In the present study, fluorine-carbon distances up to 8 Å were probed, giving insight into the API structure, crystal packing, and assignments. Most importantly, the study demonstrates a method for probing an intimate molecular level contact between an amorphous API and a polymer in an SDD, giving insights into molecular association and understanding of the role of the polymer in API stability (such as recrystallization, degradation, etc.) in such novel composite drug products.

NMR studies of macroscopic and microscopic properties of liquid crystals

International Nuclear Information System (INIS)

Hughes, J.R.

1998-03-01

The work presented is concerned with studies of orientational order in liquid crystals and the behaviour of certain mesophases. The experimental technique used in common with all the work is deuterium NMR spectroscopy. Much of the work involves studies of the orientational order of deuteriated solute molecules dissolved in liquid crystal solvents. Chapter 1 gives an introduction to liquid crystals followed by a quantitative description of orientational order. Deuterium NMR in liquid crystals is described and an outline of the molecular field theory behind the orientational order of a rigid, biaxial solute in a uniaxial mesophase is given. In Chapter 2 a novel type of mesophase induction is studied using NMR, where a solute induces up to two extra phases in a discotic mesogen depending on its concentration. The purpose of this work is to try to gain an understanding into the mechanism of the phase induction involved. Chapter 3 is concerned primarily with the macroscopic behaviour of the nematic phase formed by a semi-rigid main-chain polymer in solution. Of particular interest is the study of the reorientation of the monodomain, once the director has been rotated with respect to the magnetic field of the NMR spectrometer. A mesogen which has been claimed to exhibit a biaxial nematic phase is studied in Chapter 4, in order to determine the symmetry of the phase using NMR. Finally, Chapter 5 deals with the differing behaviour of a liquid crystal monomer and its dimer dissolved in common nematic solvents in order to determine whether this agrees with molecular field theory. (author)

Novel NMR tools to study structure and dynamics of biomembranes.

Science.gov (United States)

Gawrisch, Klaus; Eldho, Nadukkudy V; Polozov, Ivan V

2002-06-01

Nuclear magnetic resonance (NMR) studies on biomembranes have benefited greatly from introduction of magic angle spinning (MAS) NMR techniques. Improvements in MAS probe technology, combined with the higher magnetic field strength of modern instruments, enables almost liquid-like resolution of lipid resonances. The cross-relaxation rates measured by nuclear Overhauser enhancement spectroscopy (NOESY) provide new insights into conformation and dynamics of lipids with atomic-scale resolution. The data reflect the tremendous motional disorder in the lipid matrix. Transfer of magnetization by spin diffusion along the proton network of lipids is of secondary relevance, even at a long NOESY mixing time of 300 ms. MAS experiments with re-coupling of anisotropic interactions, like the 13C-(1)H dipolar couplings, benefit from the excellent resolution of 13C shifts that enables assignment of the couplings to specific carbon atoms. The traditional 2H NMR experiments on deuterated lipids have higher sensitivity when conducted on oriented samples at higher magnetic field strength. A very large number of NMR parameters from lipid bilayers is now accessible, providing information about conformation and dynamics for every lipid segment. The NMR methods have the sensitivity and resolution to study lipid-protein interaction, lateral lipid organization, and the location of solvents and drugs in the lipid matrix.

Overcoming the solubility limit with solubility-enhancement tags: successful applications in biomolecular NMR studies

International Nuclear Information System (INIS)

Zhou Pei; Wagner, Gerhard

2010-01-01

Although the rapid progress of NMR technology has significantly expanded the range of NMR-trackable systems, preparation of NMR-suitable samples that are highly soluble and stable remains a bottleneck for studies of many biological systems. The application of solubility-enhancement tags (SETs) has been highly effective in overcoming solubility and sample stability issues and has enabled structural studies of important biological systems previously deemed unapproachable by solution NMR techniques. In this review, we provide a brief survey of the development and successful applications of the SET strategy in biomolecular NMR. We also comment on the criteria for choosing optimal SETs, such as for differently charged target proteins, and recent new developments on NMR-invisible SETs.

NMR studies of Na+-anion association effects in polymer electrolytes

International Nuclear Information System (INIS)

Greenbaum, S.G.; Pak, Y.S.; Wintergill, M.C.; Fontanella, J.J.

1988-01-01

23 Na nuclear magnetic resonance (NMR) measurements on poly (propylene oxide) (PPO) and siloxane based polymer electrolytes containing various sodium salts at a single nominal concentration are reported. In addition, differential scanning calorimetry (DSC) and electrical conductivity studies were carried out on the PPO materials. The NMR-determined mobile Na + concentrations and DSC results provide evidence for ionic aggregation effects which, for some samples, result in salt precipitation at elevated temperatures. 23 Na chemical shifts observed in solid state NMR due to mobile Na + -anion interactions influence ionic transport as well as the number of available carriers. (author). 19 refs.; 7 figs

Applications of 1H-NMR relaxometry in experimental liver studies

International Nuclear Information System (INIS)

Holzmueller, P.

1992-01-01

Purpose of this study was to investigate applications of proton nuclear magnetic resonance ( 1 H-NMR) relaxometry in experimental medicine. Relaxometry was performed by measurements of spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation time parameters on liver biopsies up to four hours after biopsy excision. Variations of relaxation times due to species and strain, different sample handling and different liver damage models, ethionine fatty liver and paracetamol liver necrosis, were investigated. Cell integrity effects were studied on homogenized liver samples. Relaxation time parameters, especially 'main' components T 1A and T 2A of biexponential model fit, were identified to react very sensitive after tissue damages as well as to cell viability. Thus, investigation of stored liver grafts was performed in order to evaluate the possibility of a rapid liver graft viability testing method for human liver transplantation surgery by 1 H-NMR relaxometry. Another series of measurements was performed to investigate the applicability of isoflurane anesthesia for in vivo NMR experiments. This study proved the good appropriateness of isoflurane for that purpose provided that physiological monitoring and individual adjustment of anesthesia are performed. In these investigations it could be revealed that mainly T 1A and T 2A are influenced by tissue condition and that different information is inherent in these two parameters, with T 2A reflecting tissue viability and changes of tissue conditions very sensitively but rather unspecifically in respect to the damage applied. Based on these results the following future applications of 1 H-NMR relaxometry are suggested : (1) model investigations, (2) investigation of given pathologies, (3) investigation of basic requirements for in vivo NMR and (4) application in a liver graft viability testing protocol, which seems to be the most important future application of 1 H-NMR relaxometry in medicine. (author)

On-Going Bentonite Pore Water Studies by NMR and SAXS

International Nuclear Information System (INIS)

Carlsson, Torbjoern; Muurinen, Arto; Root, Andrew

2013-01-01

Compacted water-saturated MX-80 bentonite is presently being studied by SAXS and NMR in order to quantify the major pore water phases in the bentonite. The SAXS and NMR measurements gave very similar results indicating that the pore water is mainly distributed between two major phases (interlayer and non-interlayer water) and also indicate how these phases depend on the bentonite dry density. The results from the SAXS and NMR studies at VTT indicate the same thing: - The pore water in water-saturated compacted (?dry = 0.7-1.6 g/cm 3 ) bentonite is divided into two main phases: interlayer water and non-interlayer water. - The amounts of these pore water phases can be determined quantitatively with the above methods. (authors)

Multinuclear MAS NMR studies on coked zeolites H-ZSM-5

International Nuclear Information System (INIS)

Ernst, H.; Freude, D.; Hunger, M.; Pfeifer, H.

1991-01-01

During the cracking process carbonaceous materials are deposited on the outer or inner surface of the catalyst. These deposits are in many cases the main cause of catalyst deactivation. Magic angle spinning (MAS) NMR investigations and catalytic n-hexane cracking were carried out on H-ZSM-5 zeolites after a mild hydrothermal de-alumination. By 13 C CP MAS NMR it could be shown that the enhanced catalytic activity does not enhance the coke formation and that the chemical nature of these deposits is essentially aromatic. From 1 H MAS NMR studies performed on shallow-bed activated sealed samples and 27 Al and 29 Si MAS NMR on rehydrated samples it follows that for high coke concentrations the catalyst deactivation is caused mainly by blocking of Broensted acid sites. (author). 27 refs.; 3 figs.; 2 tabs

The covariance of the differences between experimental and theoretical chemical shifts as an aid for assigning two-dimensional heteronuclear correlation solid-state NMR spectra

Czech Academy of Sciences Publication Activity Database

Czernek, Jiří; Brus, Jiří

2014-01-01

Roč. 608, 21 July (2014), s. 334-339 ISSN 0009-2614 R&D Projects: GA ČR(CZ) GA14-03636S Institutional support: RVO:61389013 Keywords : NMR * DFT * covariance Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.897, year: 2014

Phenolic Glycosides from Capsella bursa-pastoris (L. Medik and Their Anti-Inflammatory Activity

Directory of Open Access Journals (Sweden)

Joon Min Cha

2017-06-01

Full Text Available A new sesquilignan glycoside 1, together with seven known phenolic glycosides 2–8 were isolated from the aerial parts of Capsella bursa-pastoris. The chemical structure of the new compound 1 was elucidated by extensive nuclear magnetic resonance (NMR data (1H- and 13C-NMR, 1H-1H correlation spectroscopy (1H-1H COSY, heteronuclear single-quantum correlation (HSQC, heteronuclear multiple bond correlation (HMBC, and nuclear overhauser effect spectroscopy (NOESY and HR-FABMS analysis. The anti-inflammatory effects of 1–8 were evaluated in lipopolysaccharide (LPS-stimulated murine microglia BV-2 cells. Compounds 4 and 7 exhibited moderate inhibitory effects on nitric oxide production in LPS-activated BV-2 cells, with IC50 values of 17.80 and 27.91 µM, respectively.

NMR studies of multiphase flows II

Energy Technology Data Exchange (ETDEWEB)

Altobelli, S.A.; Caprihan, A.; Fukushima, E. [Lovelace Institutes, Albuquerque, NM (United States)] [and others

1995-12-31

NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

NMR spectroscopy applied to the eye: Drugs and metabolic studies

Energy Technology Data Exchange (ETDEWEB)

Saether, Oddbjoern

2005-07-01

NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

NMR spectroscopy applied to the eye: Drugs and metabolic studies

International Nuclear Information System (INIS)

Saether, Oddbjoern

2005-01-01

NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

NMR structural studies of peptides and proteins in membranes

Energy Technology Data Exchange (ETDEWEB)

Opella, S J [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Chemistry

1994-12-31

The use of NMR methodology in structural studies is described as applicable to larger proteins, considering that the majority of membrane proteins is constructed from a limited repertoire of structural and dynamic elements. The membrane associated domains of these proteins are made up of long hydrophobic membrane spanning helices, shorter amphipathic bridging helices in the plane of the bilayer, connecting loops with varying degrees of mobility, and mobile N- and C- terminal sections. NMR studies have been successful in identifying all of these elements and their orientations relative to each other and the membrane bilayer 19 refs., 9 figs.

NMR studies of phase behaviour in polyacrylonitrile solutions

International Nuclear Information System (INIS)

Golightly, J.A.

1998-10-01

The aim of the thesis was to study the phase behaviour of aqueous polyacrylonitrile/NaSCN solutions using a variety of nuclear magnetic resonance techniques. Polyacrylonitrile (PAN) is the basis of the acrylic fibre industry, as such fibres contain at least 85% PAN. Despite this industrial importance, the available literature describing the phase behaviour of PAN in solution is far from comprehensive. Bulk 1 H NMR relaxation measurements were carried out over a wide range of concentrations and temperatures to probe the molecular dynamics of the PAN and water molecules. The relaxation data was found to be biexponential decay for all samples, the relative amplitudes of which were shown to be equal to the ratio of PAN protons to water protons. Both species were found to be in the regime of rapid molecular motion. Bulk 1 H NMR self diffusion measurements, using the PFGSTE technique, exhibited a bi-exponential decay of the echo amplitudes. By careful selection of the observation time, Δ, it was possible to independently probe the water and PAN translational diffusion. A background gradient, resulting from inhomogeneities of the magnetic field, complicated the analysis of the data and a novel polynomial least squares fitting procedure was devised to overcome this effect. The measured attenuation of the water diffusion coefficients (D∼10 -6 -10 -5 cm 2 s -1 ) with increasing PAN volume fraction was modelled according to various theories, including free volume and scaling laws. The study of the PAN diffusion coefficient (D∼10 -7 -10 -6 cm 2 s -1 ) was limited by the experimental constraints of the NMR spectrometer. A 1 H NMR one-dimensional imaging technique was used to study the non-solvent induced phase separation (coagulation) of a PAN solution. The time dependence of the measured profiles allowed observation of the coagulation process. A diffusion model was developed to fit the experimental data using a semi-infinite diffusion framework. The fitting parameters

PVT Degradation Studies: NMR Analysis

Energy Technology Data Exchange (ETDEWEB)

Cho, Herman M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-06-06

Under certain environmental conditions, polyvinyl toluene (PVT) plastic scintillator has been observed to undergo internal fogging. Nuclear magnetic resonance spectroscopy has been used to elucidate the state of water inside the PVT. The deuterium NMR results show that water absorbed by PVT under warm, humid conditions enters several distinct environments, and when the PVT is transferred from incubation to ambient temperature and humidity the water is lost on a time scale of a few hours from these samples. Most of the deuterium NMR peaks can be assigned to bulk liquid water, but almost 35% of the detected signal intensity is contained in a resonance that resembles spectra of water contained in nanometer-scale pores in mesoporous carbon.

nmr spectroscopic study and dft calculations of giao nmr shieldings

African Journals Online (AJOL)

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3Department of Physics, Arts and Science Faculty, Dumlupinar University, Kütahya, ... 1H, 13C NMR chemical shifts and 1JCH coupling constants of .... then estimated using the corresponding TMS shieldings calculated in advance at the same.

Solid-state NMR studies of form I of atorvastatin calcium.

Science.gov (United States)

Wang, Wei David; Gao, Xudong; Strohmeier, Mark; Wang, Wei; Bai, Shi; Dybowski, Cecil

2012-03-22

Solid-state (13)C, (19)F, and (15)N magic angle spinning NMR studies of Form I of atorvastatin calcium are reported, including chemical shift tensors of all resolvable carbon sites and fluorine sites. The complete (13)C and (19)F chemical shift assignments are given based on an extensive analysis of (13)C-(1)H HETCOR and (13)C-(19)F HETCOR results. The solid-state NMR data indicate that the asymmetric unit of this material contains two atorvastatin molecules. A possible structure of Form I of atorvastatin calcium (ATC-I), derived from solid-state NMR data and density functional theory calculations of various structures, is proposed for this important active pharmaceutical ingredient (API).

27Al NMR studies of NpPd5Al2

International Nuclear Information System (INIS)

Chudo, H.; Sakai, H.; Tokunaga, Y.; Kambe, S.; Aoki, D.; Homma, Y.; Shiokawa, Y.; Haga, Y.; Ikeda, S.; Matsuda, T.D.; Onuki, Y.; Yasuoka, H.

2009-01-01

We present 27 Al NMR studies for a single crystal of the Np-based superconductor NpPd 5 Al 2 (T c =4.9K). We have observed a five-line 27 Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T c . The temperature dependence of the 27 Al nuclear spin-lattice relaxation rate shows no coherence peak below T c , indicating that NpPd 5 Al 2 is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd 5 Al 2 .

Experimental benchmarking of quantum control in zero-field nuclear magnetic resonance.

Science.gov (United States)

Jiang, Min; Wu, Teng; Blanchard, John W; Feng, Guanru; Peng, Xinhua; Budker, Dmitry

2018-06-01

Demonstration of coherent control and characterization of the control fidelity is important for the development of quantum architectures such as nuclear magnetic resonance (NMR). We introduce an experimental approach to realize universal quantum control, and benchmarking thereof, in zero-field NMR, an analog of conventional high-field NMR that features less-constrained spin dynamics. We design a composite pulse technique for both arbitrary one-spin rotations and a two-spin controlled-not (CNOT) gate in a heteronuclear two-spin system at zero field, which experimentally demonstrates universal quantum control in such a system. Moreover, using quantum information-inspired randomized benchmarking and partial quantum process tomography, we evaluate the quality of the control, achieving single-spin control for 13 C with an average fidelity of 0.9960(2) and two-spin control via a CNOT gate with a fidelity of 0.9877(2). Our method can also be extended to more general multispin heteronuclear systems at zero field. The realization of universal quantum control in zero-field NMR is important for quantum state/coherence preparation, pulse sequence design, and is an essential step toward applications to materials science, chemical analysis, and fundamental physics.

Trace Oxygen Sensitive Material Based on Two Porphyrin Derivatives in a Heterodimeric Complex

Directory of Open Access Journals (Sweden)

Eugenia Fagadar-Cosma

2017-10-01

Full Text Available The successful preparation of a novel dimer complex formed between 5,10,15,20-tetrakis(3,4-dimethoxyphenyl-porphyrin Fe(III chloride and (5,10,15,20-tetraphenylporphinato dichlorophosphorus(V chloride using the well-known reactivity of the P–X bond is reported. The obtained complex was characterized by UV-vis, Fourier transform infrared spectroscopy (FT-IR, fluorescence, 1H-NMR, 13C-NMR, and 31P-NMR spectroscopic techniques and also by additional Heteronuclear Single Quantum Coherence (HSQC and Heteronuclear Multiple Bond Correlation (HMBC experiments in order to correctly assign the NMR signals. Scanning electron microscopy (SEM and EDX quantifications completed the characterizations. This novel porphyrin dimer complex demonstrated fluorescence sensing of H2O2 in water for low oxygen concentrations in the range of 40–90 µM proving medical relevance for early diagnosis of diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and even cancer because higher concentrations of H2O2 than 50 μM are consideredcytotoxic for life. Due to its optical properties, this novel metalloporphyrin–porphyrin based complex is expected to show PDT and bactericidal activity under visible-light irradiation.

Adsorption of asymmetric rigid rods or heteronuclear diatomic moleculeson homogeneous surfaces

Science.gov (United States)

Engl, W.; Courbin, L.; Panizza, P.

2004-10-01

We treat the adsorption on homogeneous surfaces of asymmetric rigid rods (like for instance heteronuclear diatomic molecules). We show that the n→0 vector spin formalism is well suited to describe such a problem. We establish an isomorphism between the coupling constants of the magnetic Hamiltonian and the adsorption parameters of the rigid rods. By solving this Hamiltonian within a mean-field approximation, we obtain analytical expressions for the densities of the different rod’s configurations, both isotherm and isobar adsorptions curves. The most probable configurations of the molecules (normal or parallel to the surface) which depends on temperature and energy parameters are summarized in a diagram. We derive that the variation of Qv , the heat of adsorption at constant volume, with the temperature is a direct signature of the adsorbed molecules configuration change. We show that this formalism can be generalized to more complicated problems such as for instance the adsorption of symmetric and asymmetric rigid rods mixtures in the presence or not of interactions.

[Derivative spectrophotometric and NMR spectroscopic study in pharmaceutical science].

Science.gov (United States)

Kitamura, Keisuke

2007-10-01

This review starts with an introduction of derivative spectrophotometry followed by a description on the construction of a personal computer-assisted derivative spectrophotometric (DS) system. An acquisition system for inputting digitalized absorption spectra into personal computers and a BASIC program for calculating derivative spectra were developed. Then, applications of the system to drug analyses that are difficult with traditional absorption methods are described. Following this, studies on the interactions of drugs with biological macromolecules by the DS and NMR methods were discussed. An (1)H NMR study elucidated that the small unilamellar vesicle (SUV) has a single membrane made of a phosphatidylcholine bilayer, and that chlorpromazine interacts with both the outer and inner layers. (13)C NMR revealed a reduction of the dissociation constants of phenothiazine drugs due to their interaction with SUV. The partition coefficients of phenothiazine, benzodiazepine and steroid drugs in an SUV-water system and the effects of cholesterol or amino lipids content on these partition coefficients were examined by the DS method. The binding constants of phenothiazine drugs to bovine serum albumin (BSA) and the influence of Na(+), K(+), Cl(-), Br(-), and I(-) on these binding constants were determined by DS. It was found that I(-), Br(-), Cl(-) reduce the binding constants in this order, and that Na(+) and K(+) have no effect. A (19)F NMR study revealed that triflupromazine binds to BSA and human serum albumin in two regions including Site II with different populations, and that a nonsteroidal anti-inflammatory drug, niflumic acid, binds Sites Ia and Ib.

Isotope labeling strategies for NMR studies of RNA

International Nuclear Information System (INIS)

Lu, Kun; Miyazaki, Yasuyuki; Summers, Michael F.

2010-01-01

The known biological functions of RNA have expanded in recent years and now include gene regulation, maintenance of sub-cellular structure, and catalysis, in addition to propagation of genetic information. As for proteins, RNA function is tightly correlated with structure. Unlike proteins, structural information for larger, biologically functional RNAs is relatively limited. NMR signal degeneracy, relaxation problems, and a paucity of long-range 1 H- 1 H dipolar contacts have limited the utility of traditional NMR approaches. Selective isotope labeling, including nucleotide-specific and segmental labeling strategies, may provide the best opportunities for obtaining structural information by NMR. Here we review methods that have been developed for preparing and purifying isotopically labeled RNAs, as well as NMR strategies that have been employed for signal assignment and structure determination.

Study of molecular movements in some organic crystals by NMR

International Nuclear Information System (INIS)

Alexandre, M.

1971-01-01

After a discussion on molecular crystals (generalities, movements within molecular solids, study of movements, complexes by charge transfer) and some specific ones (molecular complexes of trinitrobenzene or TNB), this research thesis reports the use of nuclear magnetic resonance (NMR) to study molecular movements: generalities on broadband NMR, spin relaxation and strong field network, observation of the absorption signal and measurement of the second moment. The last part reports and discusses experimental results obtained on TNB-naphthalene, on TNB-azulene, on TNB-benzothiophene, and on TNB-indole

Proton NMR studies on Megaphaera elsdenii flavodoxin : structure elucidation by 2D-NMR and implications

NARCIS (Netherlands)

Mierlo, van C.

1990-01-01

¹H NMR techniques have been applied for a thorough study of the uncrystallizable Megasphaera elsdenii flavodoxin in its three redox states. The aim of the research project described in this thesis was to obtain answers regarding questions

Trace level detection of compounds related to the chemical weapons convention by 1H-detected 13C NMR spectroscopy executed with a sensitivity-enhanced, cryogenic probehead.

Science.gov (United States)

Cullinan, David B; Hondrogiannis, George; Henderson, Terry J

2008-04-15

Two-dimensional 1H-13C HSQC (heteronuclear single quantum correlation) and fast-HMQC (heteronuclear multiple quantum correlation) pulse sequences were implemented using a sensitivity-enhanced, cryogenic probehead for detecting compounds relevant to the Chemical Weapons Convention present in complex mixtures. The resulting methods demonstrated exceptional sensitivity for detecting the analytes at trace level concentrations. 1H-13C correlations of target analytes at chemical shift information could be derived quickly and simultaneously from the resulting spectra. The fast-HMQC pulse sequences generated magnitude mode spectra suitable for detailed analysis in approximately 4.5 h and can be used in experiments to efficiently screen a large number of samples. The HSQC pulse sequences, on the other hand, required roughly twice the data acquisition time to produce suitable spectra. These spectra, however, were phase-sensitive, contained considerably more resolution in both dimensions, and proved to be superior for detecting analyte 1H-13C correlations. Furthermore, a HSQC spectrum collected with a multiplicity-edited pulse sequence provided additional structural information valuable for identifying target analytes. The HSQC pulse sequences are ideal for collecting high-quality data sets with overnight acquisitions and logically follow the use of fast-HMQC pulse sequences to rapidly screen samples for potential target analytes. Use of the pulse sequences considerably improves the performance of NMR spectroscopy as a complimentary technique for the screening, identification, and validation of chemical warfare agents and other small-molecule analytes present in complex mixtures and environmental samples.

High resolution NMR study of cellulose in solid state and in solution

International Nuclear Information System (INIS)

Saint-Germain, Jean

1983-01-01

This research thesis reports the study of native cellulose (cotton) and wood by nuclear magnetic resonance (NMR). As far as the cotton spectrum is concerned, the author assigned resonances which more specifically corresponded to amorphous or crystalline areas. Wood was studied in its bulk condition, and resonances have been determined for the different wood components. The behaviour of cellulose in solution in a solvent has been studied by liquid high resolution NMR. The solvation mechanism has been determined and a study of model components of the macromolecule allowed a conformational study of cellulose in this solvent to be performed. Bi-dimensional NMR and longitudinal relaxation time measurements highlighted the existence of an intramolecular hydrogen bond in the cellulose in solution [fr

High resolution deuterium NMR studies of bacterial metabolism

Energy Technology Data Exchange (ETDEWEB)

Aguayo, J.B.; Gamcsik, M.P.; Dick, J.D.

1988-12-25

High resolution deuterium NMR spectra were obtained from suspensions of five bacterial strains: Escherichia coli, Clostridium perfringens, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus aureus. Deuterium-labeled D-glucose at C-1, C-2, and C-6 was used to monitor dynamically anaerobic metabolism. The flux of glucose through the various bacterial metabolic pathways could be determined by following the disappearance of glucose and the appearance of the major end products in the 2H NMR spectrum. The presence of both labeled and unlabeled metabolites could be detected using 1H NMR spectroscopy since the proton resonances in the labeled species are shifted upfield due to an isotopic chemical shift effect. The 1H-1H scalar coupling observed in both the 2H and 1H NMR spectra was used to assign definitively the resonances of labeled species. An increase in the intensity of natural abundance deuterium signal of water can be used to monitor pathways in which a deuteron is lost from the labeled metabolite. The steps in which label loss can occur are outlined, and the influence these processes have on the ability of 2H NMR spectroscopy to monitor metabolism are assessed.

High resolution deuterium NMR studies of bacterial metabolism

International Nuclear Information System (INIS)

Aguayo, J.B.; Gamcsik, M.P.; Dick, J.D.

1988-01-01

High resolution deuterium NMR spectra were obtained from suspensions of five bacterial strains: Escherichia coli, Clostridium perfringens, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus aureus. Deuterium-labeled D-glucose at C-1, C-2, and C-6 was used to monitor dynamically anaerobic metabolism. The flux of glucose through the various bacterial metabolic pathways could be determined by following the disappearance of glucose and the appearance of the major end products in the 2H NMR spectrum. The presence of both labeled and unlabeled metabolites could be detected using 1H NMR spectroscopy since the proton resonances in the labeled species are shifted upfield due to an isotopic chemical shift effect. The 1H-1H scalar coupling observed in both the 2H and 1H NMR spectra was used to assign definitively the resonances of labeled species. An increase in the intensity of natural abundance deuterium signal of water can be used to monitor pathways in which a deuteron is lost from the labeled metabolite. The steps in which label loss can occur are outlined, and the influence these processes have on the ability of 2H NMR spectroscopy to monitor metabolism are assessed

New bisbenzylisoquinoline alkaloid from Laureliopsis philippiana

DEFF Research Database (Denmark)

Stærk, Dan; Thi, Loi Pham; Rasmussen, Hasse Bonde

2009-01-01

Phytochemical investigation of Laureliopsis philippiana resulted in isolation of a new bisbenzylisoquinoline alkaloid (1) named laureliopsine A. The structure was established by spectroscopic methods, including 2D homo- and heteronuclear NMR experiments. This finding of a bisbenzylisoquinoline al...

Solid NMR study of lithium ions accommodated in various transition metal oxides

International Nuclear Information System (INIS)

Kanzaki, Yasushi; Suzuki, Noriko

2008-01-01

Solid NMR was used to elucidate the lithium accommodation/extraction reaction in various transition metal oxides. The first study was the lithium ion exchange reaction of titanium antimonic acid (TiSbA). The effect of hydration on the selectivity of lithium ion in the solid phase was examined using 7 Li NMR. The second study was the irreversible ion exchange behavior of HNbO 3 . The selectivity for the lithium ion and the irreversible behavior were examined using 1 H and 7 Li NMR. The third study was the isotope separation between 6 Li and 7 Li in various inorganic ion exchangers. The high isotope separation coefficient was ascribed to the degree of dehydration during the ion exchange reaction. The degree of dehydration was examined by 1 H and 7 Li NMR studies. The last study was determining the mechanism of the lithium accommodation/extraction reaction of λ-MnO 2 in an aqueous solution. The different paths between the accommodation and extraction and the formation of MnO 4- during the accommodation were determined by chemical analysis. The Knight shift in the 7 Li MAS-NMR spectra of Li 0.5 MnO 2 suggested the localization of the electron density on the lithium nuclei. An XPS study also suggested the presence of an electron density on the lithium nuclei. A pH-independent redox couple was assumed to account for the accommodation/extraction reaction of lithium ions, such as Li(I)/Li(0). (author)

High Field In Vivo 13C Magnetic Resonance Spectroscopy of Brain by Random Radiofrequency Heteronuclear Decoupling and Data Sampling

Science.gov (United States)

Li, Ningzhi; Li, Shizhe; Shen, Jun

2017-06-01

In vivo 13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo 13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo 13C-MRS, alkanyl carbons are detected in the spectra range of 10-65ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH=125-145 Hz). Two main proton decoupling methods have been developed: broadband stochastic decoupling and coherent composite or adiabatic pulse decoupling (e.g., WALTZ); the latter is widely used because of its efficiency and superb performance under inhomogeneous B1 field. Because the RF power required for proton decoupling increases quadratically with field strength, in vivo 13C-MRS using coherent decoupling is often limited to low magnetic fields (protons via weak long-range 1H-13C scalar couplings, which can be decoupled using low RF power broadband stochastic decoupling. Recently, the carboxylic/amide 13C-MRS technique using low power random RF heteronuclear decoupling was safely applied to human brain studies at 7T. Here, we review the two major decoupling methods and the carboxylic/amide 13C-MRS with low power decoupling strategy. Further decreases in RF power deposition by frequency-domain windowing and time-domain random under-sampling are also discussed. Low RF power decoupling opens the possibility of performing in vivo 13C experiments of human brain at very high magnetic fields (such as 11.7T), where signal-to-noise ratio as well as spatial and temporal spectral resolution are more favorable than lower fields.

Xenon-Water Interaction in Bacterial Suspensions as Studied by NMR

DEFF Research Database (Denmark)

Rodin, V.; Ponomarev, Alexander; Gerasimov, Maxim

2017-01-01

suspensions of Escherichia coli in the presence of xenon using nuclear magnetic resonance (NMR). The work studied how the spin-lattice relaxation times of water protons in suspension change under xenon conditions. Xenon is able to form clathrate hydrates with water molecules at a temperature above the melting...... point of ice. The work studied NMR relaxation times which reflect the rotation freedom of water molecules in suspension. Lower relaxation times indicate reduced rotational freedom of water. Single exponential behavior of spin-lattice relaxation of protons in the suspensions of microorganisms has been...

Study of β-NMR for Liquid Biological Samples

CERN Document Server

Beattie, Caitlin

2017-01-01

β-NMR is an exotic form of NMR spectroscopy that allows for the characterization of matter based on the anisotropic β-decay of radioactive probe nuclei. This has been shown to be an effective spectroscopic technique for many different compounds, but its use for liquid biological samples is relatively unexplored. The work at the VITO line of ISOLDE seeks to employ this technique to study such samples. Currently, preparations are being made for an experiment to characterize DNA G-quadruplexes and their interactions with stabilizing cations. More specifically, the work in which I engaged as a summer student focused on the experiment’s liquid handling system and the stability of the relevant biological samples under vacuum.

Recent Pulse Sequences for Heteronuclear Long-Range Correlation and More

DEFF Research Database (Denmark)

Sørensen, Ole W.

This talk will give an overview of the key elements and principles of experiments listed on http://www.crc.dk/nmr/, from where also pulse programs in Bruker and Varian format can be downloaded.......This talk will give an overview of the key elements and principles of experiments listed on http://www.crc.dk/nmr/, from where also pulse programs in Bruker and Varian format can be downloaded....

Rapid and novel discrimination and quantification of oleanolic and ursolic acids in complex plant extracts using two-dimensional nuclear magnetic resonance spectroscopy-Comparison with HPLC methods

International Nuclear Information System (INIS)

Kontogianni, Vassiliki G.; Exarchou, Vassiliki; Troganis, Anastassios; Gerothanassis, Ioannis P.

2009-01-01

A novel strategy for NMR analysis of mixtures of oleanolic and ursolic acids that occur in natural products is described. These important phytochemicals have similar structure and their discrimination and quantification is rather difficult. We report herein the combined use of proton-carbon heteronuclear single-quantum coherence ( 1 H- 13 C HSQC) and proton-carbon heteronuclear multiple-bond correlation ( 1 H- 13 C HMBC) NMR spectroscopy, in the identification and quantitation of oleanolic acid (OA) and ursolic acid (UA)in plant extracts of the Lamiaceae and Oleaceae family. The combination of 1 H- 13 C HSQC and 1 H- 13 C HMBC techniques allows the connection of the proton and carbon-13 spins across the molecular backbone resulting in the identification and, thus, discrimination of oleanolic and ursolic acid without resorting to physicochemical separation of the components. The quantitative results provided by 2D 1 H- 13 C HSQC NMR data were obtained within a short period of time (∼14 min) and are in excellent agreement with those obtained by HPLC, which support the efficiency of the suggested methodology

TD-NMR studies on CuSO{sub 4} salt hydrates

Energy Technology Data Exchange (ETDEWEB)

Nestle, Nikolaus; Magin, Peter; Wengeler, Robert [BASF Aktiengesellschaft, Ludwigshafen (Germany); Kleinschmidt, Sebastian [Universitaet Magdeburg, FB Chemie (Germany)

2008-07-01

Despite the high concentration of paramagnetic copper ions, solid CuSO{sub 4} hydrates exhibit surprizingly narrow NMR signals. This is known since the late 1940s. Using TD-NMR methods established for polymer studies, the relaxation behaviour of CuSO{sub 4} preparations with different water content was studied at room temperature. For the water content of the pentahydrate and below, the NMR signal exhibits a pure solid-state-type magnetization decay behaviour. For slightly overstoichiometric moisture contents, a liquid-like signal is observed in addition to the solid signal. However, the relative amplitudes of the solid and the liquid signal do not mirror the stoichiometric composition of the pentahydrate and the excess water. Instead, the solid signal amplitude only accounts for four hydrate water molecules while the fifth water exhibits rapid exchange with the liquid phase and thus contributes to the liquid-type signal. This finding is in good agreement to results from investigations into the crystal structure of solid CuSO4 pentahydrate.

NMR study of rare earth and actinide complexes

International Nuclear Information System (INIS)

Villardi de Montlaur de, G.C.

1978-01-01

Proton magnetic resonance studies of lanthanide shift reagents with olefin-transition metal complexes, monoamines and diamines as substrates are described. Shift reagents for olefins are reported: Lnsup(III)(fod) 3 can induce substantial shifts in the nmr spectra of a variety of olefins when silver 1-heptafluororobutyrate is used to complex the olefin. The preparation, properties and efficiency of such systems are described. Configurational aspects and exchange processes of Lnsup(III)(fod) 3 complexes with secondary and tertiary monoamines are analysed by means of dynamic nmr. Factors influencing the stability and the stoichiometry of these complexes and various processes such as nitrogen inversion and ligand exchange are discussed. At low temperature, ring inversion can be slow on an nmr time-scale for Lnsup(III)(fod) 3 -diamino chelates. Barriers to ring inversion in substituted ethylenediamines and propanediamines are obtained. Steric factors appear to play an important role in the stability and kinetics of these bidentate species. The synthesis of uranium-IV crown-ether and cryptate complexes is described. A conformational study of these compounds show evidence of an insertion of the paramagnetic cation as witnessed by the large induced shifts observed. The insertion of uranium in the macrocyclic ligand of a UCl 4 -dicyclohexyl-18-crown-6 complex is confirmed by an X-ray structural determination [fr

NMR Studies of Polymer Nanocomposites

National Research Council Canada - National Science Library

Greenbaum, Steve

2001-01-01

.... The primary tool is pulsed field gradient NMR. A static field gradient method was developed which makes possible variable pressure diffusion measurement, and the application to the important fuel cell membrane NAFION constitute the first results...

NMR

International Nuclear Information System (INIS)

Kneeland, J.B.; Lee, B.C.P.; Whalen, J.P.; Knowles, R.J.R.; Cahill, P.T.

1984-01-01

Although still quite new, NMR imaging has already emerged as a safe, noninvasive, painless, and effective diagnostic modality requiring no ionizing radiation. Also, NMR appears already to have established itself as the method of choice for the examination of the brain spinal cord (excluding herniated disks). Another area in which NMR excels is in the examination of the pelvis. The use of surface coils offers the promise of visualizing structures with resolution unobtainable by any other means. In addition, NMR, with its superb visualization of vascular structures and potential ability to measure flow, may soon revolutionize the diagnosis of cardiovascular disease. Finally, NMR, through biochemically and physiologically based T/sub 1/ and T/sub 2/ indices or through spectroscopy, may provide a means of monitoring therapeutic response so as to permit tailoring of treatment to the individual patient. In short, NMR is today probably at the same stage as the x-ray was in Roentgen's day

Triple-resonance multidimensional NMR study of calmodulin complexed with the binding domain of skeletal muscle myosin light-chain kinase: Indication of a conformational change in the central helix

International Nuclear Information System (INIS)

Ikura, Mitsuhiko; Kay, L.E.; Bax, A.; Krinks, M.

1991-01-01

Heteronuclear 3D and 4D NMR experiments have been used to obtain 1 H, 13 C, and 15 N backbone chemical shift assignments in Ca 2+ -loaded clamodulin complexed with a 26-residue synthetic peptide (M13) corresponding to the calmodulin-bionding domain (residues 577-602) of rabbit skeletal muscle muosin light-chain kinase. Comparison of the chemical shift values with those observed in peptide-free calmodulin shows that binding of M13 peptide induces substantial chemical shift changes that are not localized in one particular region of the protein. The largest changes are found in the first helix of the Ca 2+ -binding site 1 (E11-E14), the N-terminal portion of the central helix (M72-D78), and the second helix of the Ca 2+ -binding site 4 (F141-M145). Analysis of backbone NOE connectivities indicates a change from α-helical to an extended conformation for residues 75-77 upon complexation with M13. Upon complexation with M13, a significant decrease in the amide exchange rate is observed for residues T110, L112, G113, and E114 at the end of the second helix of site 3

Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials

Science.gov (United States)

Paik, Younkee

Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

Dynamic NMR Study of Model CMP Slurry Containing Silica Particles as Abrasives

Science.gov (United States)

Odeh, F.; Al-Bawab, A.; Li, Y.

2018-02-01

Chemical mechanical planarization (CMP) should provide a good surface planarity with minimal surface defectivity. Since CMP slurries are multi-component systems, it is very important to understand the various processes and interactions taking place in such slurries. Several techniques have been employed for such task, however, most of them lack the molecular recognition to investigate molecular interactions without adding probes which in turn increase complexity and might alter the microenvironment of the slurry. Nuclear magnetic resonance (NMR) is a powerful technique that can be employed in such study. The longitudinal relaxation times (T1) of the different components of CMP slurries were measured using Spin Echo-NMR (SE-NMR) at a constant temperature. The fact that NMR is non-invasive and gives information on the molecular level gives more advantage to the technique. The model CMP slurry was prepared in D2O to enable monitoring of T1 for the various components' protons. SE-NMR provide a very powerful tool to study the various interactions and adsorption processes that take place in a model CMP silica based slurry which contains BTA and/or glycine and/or Cu+2 ions. It was found that BTA is very competitive towards complexation with Cu+2 ions and BTA-Cu complex adsorbs on silica surface.

31P-NMR study of human pyrimidine 5'-nucleotidase deficient erythrocytes

International Nuclear Information System (INIS)

Higaki, Tsuyoshi; Kagimoto, Tadashi; Nagata, Koichi; Tanase, Sumio; Morino, Yoshimasa; Takatsuki, Kiyoshi

1982-01-01

Metabolic disorder of nucleotides in human pyrimidine 5'-nucleotidase (P5N) deficient erythrocytes was studied by 31 P-NMR with high resolution. Identification by combination of high-speed liquid chromatography revealed two-fold increases from the normal in the spectra in the α-, β- and γ-zones of nucleoside triphosphates of P5N deficient erythrocytes, 2,3-diphosphoglycerate shifted to the 0.3 ppm low magnetic field and signals of NAD and UDP-sugars(s) in the diphosphodiester zone. These results were obtained from the 31 P-NMR spectrum about one hour after blood sampling, indicating the high utility of this NMR for the diagnosis of P5N deficiency. (Chiba, N.)

Water speciation in sodium silicate glasses (quenched melts): A comprehensive NMR study

Science.gov (United States)

Xue, X.; Kanzaki, M.; Eguchi, J.

2012-12-01

Dissolution mechanism of water is an important factor governing how the dissolved water affects the physical and thermodynamic properties of silicate melts and glasses. Our previous studies have demonstrated that 1H MAS NMR in combination with 29Si-1H and 27Al-1H double-resonance NMR experiments is an effective approach for unambiguously differentiating and quantifying different water species in quenched silicate melts (glasses). Several contrasting dissolution mechanisms have been revealed depending on the melt composition: for relatively polymerized melts, the formation of SiOH/AlOH species (plus molecular H2O) and depolymerization of the network structure dominate; whereas for depolymerized Ca-Mg silicate melts, free OH (e.g. MgOH) become increasingly important (cf. [1]). The proportion of free OH species has been shown to decrease with both increasing melt polymerization (silica content) and decreasing field strength of the network modifying cations (from Mg to Ca). Our previous 1H and 29Si MAS NMR results for hydrous Na silicate glasses of limited compositions (Na2Si4O9 and Na2Si2O5) were consistent with negligible free OH (NaOH) species and depolymerizing effect of water dissolution [2]. On the other hand, there were also other studies that proposed the presence of significant NaOH species in hydrous glasses near the Na2Si2O5 composition. The purpose of this study is apply the approach of combined 1H MAS NMR and double-resonance (29Si-1H and 23Na-1H) NMR to gain unambiguous evidence for the OH speciation in Na silicate glasses (melts) as a function of composition. Hydrous Na silicate glasses containing mostly ≤ 1 wt% H2O for a range of Na/Si ratios from 0.33 to 1.33 have been synthesized by rapidly quenching melts either at 0.2 GPa using an internally heated gas pressure vessel or at 1 GPa using a piston cylinder high-pressure apparatus. NMR spectra have been acquired using a 9.4 T Varian Unity-Inova spectrometer. The 29Si and 1H chemical shifts are

Advanced NMR technology for bioscience and biotechnology

Energy Technology Data Exchange (ETDEWEB)

Hammel, P.C.; Hernandez, G.; Trewhella, J.; Unkefer, C.J. [Los Alamos National Lab., NM (US); Boumenthal, D.K. [Univ. of Utah, Salt Lake City, UT (US); Kennedy, M.A. [Pacific Northwest National Lab., Richland, WA (US); Moore, G.J. [Wayne State Univ., Detroit, MI (US)

1998-11-01

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). NMR plays critical roles in bioscience and biotechnology in both imaging and structure determination. NMR is limited, however, by the inherent low sensitivity of the NMR experiment and the demands for spectral resolution required to study biomolecules. The authors addressed both of these issues by working on the development of NMR force microscopy for molecular imaging, and high field NMR with isotope labeling to overcome limitations in the size of biomolecules that can be studied using NMR. A novel rf coil design for NMR force microscopy was developed that increases the limits of sensitivity in magnetic resonance detection for imaging, and the authors demonstrated sub-surface spatial imaging capabilities. The authors also made advances in the miniaturization of two critical NMR force microscope components. They completed high field NMR and isotope labeling studies of a muscle protein complex which is responsible for regulating muscle contraction and is too large for study using conventional NMR approaches.

NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

International Nuclear Information System (INIS)

Foerland, Kjersti

2005-01-01

In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41

NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

Energy Technology Data Exchange (ETDEWEB)

Foerland, Kjersti

2005-07-01

In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41.

Two-dimensional 1H and 31P NMR spectra of a decamer oligodeoxyribonucleotide duplex and a quinoxaline ([MeCys3, MeCys7]TANDEM) drug duplex complex

International Nuclear Information System (INIS)

Powers, R.; Olsen, R.K.; Gorenstein, D.G.

1989-01-01

Assignment of the 1H and 31P NMR spectra of a decamer oligodeoxyribonucleotide duplex, d(CCCGATCGGG), and its quinoxaline ([MeCys3, MeCys7]TANDEM) drug duplex complex has been made by two-dimensional 1H-1H and heteronuclear 31P-1H correlated spectroscopy. The 31P chemical shifts of this 10 base pair oligonucleotide follow the general observation that the more internal the phosphate is located within the oligonucleotide sequence, the more upfield the 31P resonance occurs. While the 31P chemical shifts show sequence-specific variations, they also do not generally follow the Calladine rules previously demonstrated. 31P NMR also provides a convenient monitor of the phosphate ester backbone conformational changes upon binding of the drug to the duplex. Although the quinoxaline drug, [MeCys3, MeCys7]TANDEM, is generally expected to bind to duplex DNA by bis-intercalation, only small 31P chemical shift changes are observed upon binding the drug to duplex d(CCCGATCGGG). Additionally, only small perturbations in the 1H NMR and UV spectra are observed upon binding the drug to the decamer, although association of the drug stabilizes the duplex form relative to the other states. These results are consistent with a non-intercalative mode of association of the drug. Modeling and molecular mechanics energy minimization demonstrate that a novel structure in which the two quinoxaline rings of the drug binds in the minor groove of the duplex is possible

Automated sample preparation station for studying self-diffusion in porous solids with NMR spectroscopy

Science.gov (United States)

Hedin, Niklas; DeMartin, Gregory J.; Reyes, Sebastián C.

2006-03-01

In studies of gas diffusion in porous solids with nuclear magnetic resonance (NMR) spectroscopy the sample preparation procedure becomes very important. An apparatus is presented here that pretreats the sample ex situ and accurately sets the desired pressure and temperature within the NMR tube prior to its introduction in the spectrometer. The gas manifold that supplies the NMR tube is also connected to a microbalance containing another portion of the same sample, which is kept at the same temperature as the sample in the NMR tube. This arrangement permits the simultaneous measurement of the adsorption loading on the sample, which is required for the interpretation of the NMR diffusion experiments. Furthermore, to ensure a good seal of the NMR tube, a hybrid valve design composed of titanium, a Teflon® seat, and Kalrez® O-rings is utilized. A computer controlled algorithm ensures the accuracy and reproducibility of all the procedures, enabling the NMR diffusion experiments to be performed at well controlled conditions of pressure, temperature, and amount of gas adsorbed on the porous sample.

NMR studies of transmembrane electron transport in human erythrocytes

International Nuclear Information System (INIS)

Kennett, E.C.; Bubb, W.A.; Kuchel, P.W.

2002-01-01

Full text: Electron transport systems exist in the plasma membranes of all cells. These systems appear to play a role in cell growth and proliferation, intracellular signalling, hormone responses, apoptotic events, cell defence and perhaps most importantly they enable the cell to respond to changes in the redox state of both the intra- and extracellular environments. Previously, 13 C NMR has been used to study transmembrane electron transport in human erythrocytes, specifically the reduction of extracellular 13 C-ferricyanide. NMR is a particularly useful tool for studying such systems as changes in the metabolic state of the cell can be observed concomitantly with extracellular reductase activity. We investigated the oxidation of extracellular NADH by human erythrocytes using 1 H and 31 P NMR spectroscopy. Recent results for glucose-starved human erythrocytes indicate that, under these conditions, extracellular NADH can be oxidised at the plasma membrane with the electron transfer across the membrane resulting in reduction of intracellular NAD + . The activity is inhibited by known trans-plasma membrane electron transport inhibitors (capsaicin and atebrin) and is unaffected by inhibition of the erythrocyte Band 3 anion transporter. These results suggest that electron import from extracellular NADH allows the cell to re-establish a reducing environment after the normal redox balance is disturbed

Proton Environments in Biomimetic Calcium Phosphates Formed from Mesoporous Bioactive CaO-SiO2-P2O5 Glasses in Vitro: Insights from Solid-State NMR.

Science.gov (United States)

Mathew, Renny; Turdean-Ionescu, Claudia; Yu, Yang; Stevensson, Baltzar; Izquierdo-Barba, Isabel; García, Ana; Arcos, Daniel; Vallet-Regí, María; Edén, Mattias

2017-06-22

When exposed to body fluids, mesoporous bioactive glasses (MBGs) of the CaO-SiO 2 -P 2 O 5 system develop a bone-bonding surface layer that initially consists of amorphous calcium phosphate (ACP), which transforms into hydroxy-carbonate apatite (HCA) with a very similar composition as bone/dentin mineral. Information from various 1 H-based solid-state nuclear magnetic resonance (NMR) experiments was combined to elucidate the evolution of the proton speciations both at the MBG surface and within each ACP/HCA constituent of the biomimetic phosphate layer formed when each of three MBGs with distinct Ca, Si, and P contents was immersed in a simulated body fluid (SBF) for variable periods between 15 min and 30 days. Directly excited magic-angle-spinning (MAS) 1 H NMR spectra mainly reflect the MBG component, whose surface is rich in water and silanol (SiOH) moieties. Double-quantum-single-quantum correlation 1 H NMR experimentation at fast MAS revealed their interatomic proximities. The comparatively minor H species of each ACP and HCA component were probed selectively by heteronuclear 1 H- 31 P NMR experimentation. The initially prevailing ACP phase comprises H 2 O and "nonapatitic" HPO 4 2- /PO 4 3- groups, whereas for prolonged MBG soaking over days, a well-progressed ACP → HCA transformation was evidenced by a dominating O 1 H resonance from HCA. We show that 1 H-detected 1 H → 31 P cross-polarization NMR is markedly more sensitive than utilizing powder X-ray diffraction or 31 P NMR for detecting the onset of HCA formation, notably so for P-bearing (M)BGs. In relation to the long-standing controversy as to whether bone mineral comprises ACP and/or forms via an ACP precursor, we discuss a recently accepted structural core-shell picture of both synthetic and biological HCA, highlighting the close relationship between the disordered surface layer and ACP.

Broad line NMR study of modified polypropylene fibres

International Nuclear Information System (INIS)

Olcak, D.; Sevcovic, L.; Mucha, L.

1999-01-01

Study of drawn fibres prepared from an isostatic polypropylene modified by an ethylene aminoalkylacrylate copolymer has been done using the broad line of 1 H NMR. NMR spectra were measured on the set of fibres prepared with a draw ratio λ from 1 to 5.5 at two temperatures, one of them corresponding to the onset of segmental motion and the other one is the minddle of the temperature interval as determined by decrease of the second moment M 2 . Decomposition of the spectra into elementary components related to the amorphous, intermediate and crystalline regions of partially crystalline polymers has been made. The drawing of the fibres was found to enhance the chain mobility in the amorphous region and to restrain the molecular motion in the intermediate region. Such behaviour well supports conclusions predicted in the earlier study based on the spin-lattice relaxation time T 1 and dynamic mechanical data treated using the WLF theory. (Authors)

Characterization of lithium coordination sites with magic-angle spinning NMR

Science.gov (United States)

Haimovich, A.; Goldbourt, A.

2015-05-01

Lithium, in the form of lithium carbonate, is one of the most common drugs for bipolar disorder. Lithium is also considered to have an effect on many other cellular processes hence it possesses additional therapeutic as well as side effects. In order to quantitatively characterize the binding mode of lithium, it is required to identify the interacting species and measure their distances from the metal center. Here we use magic-angle spinning (MAS) solid-state NMR to study the binding site of lithium in complex with glycine and water (LiGlyW). Such a compound is a good enzyme mimetic since lithium is four-coordinated to one water molecule and three carboxylic groups. Distance measurements to carbons are performed using a 2D transferred echo double resonance (TEDOR) MAS solid-state NMR experiment, and water binding is probed by heteronuclear high-resolution proton-lithium and proton-carbon correlation (wPMLG-HETCOR) experiments. Both HETCOR experiments separate the main complex from impurities and non-specifically bound lithium species, demonstrating the sensitivity of the method to probe the species in the binding site. Optimizations of the TEDOR pulse scheme in the case of a quadrupolar nucleus with a small quadrupole coupling constant show that it is most efficient when pulses are positioned on the spin-1/2 (carbon-13) nucleus. Since the intensity of the TEDOR signal is not normalized, careful data analysis that considers both intensity and dipolar oscillations has to be performed. Nevertheless we show that accurate distances can be extracted for both carbons of the bound glycine and that these distances are consistent with the X-ray data and with lithium in a tetrahedral environment. The lithium environment in the complex is very similar to the binding site in inositol monophosphatase, an enzyme associated with bipolar disorder and the putative target for lithium therapy. A 2D TEDOR experiment applied to the bacterial SuhB gene product of this enzyme was designed

NMR studies concerning base-base interactions in oligonucleotides

International Nuclear Information System (INIS)

Hoogen, Y.T. van den.

1988-01-01

Two main subjects are treated in the present thesis. The firsst part principally deals with the base-base interactions in single-stranded oligoribonucleotides. The second part presents NMR and model-building studies of DNA and RNA duplexes containing an unpaired base. (author). 242 refs.; 26 figs.; 24 tabs

Solid-state NMR studies of nucleic acid components

Czech Academy of Sciences Publication Activity Database

Dračínský, Martin; Hodgkinson, P.

2015-01-01

Roč. 5, č. 16 (2015), s. 12300-12310 ISSN 2046-2069 R&D Projects: GA ČR GA13-24880S Institutional support: RVO:61388963 Keywords : NMR spectroscopy * nucleic acid s * solid-state NMR Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.289, year: 2015 http://pubs.rsc.org/en/content/articlepdf/2015/ra/c4ra14404j

1H-NMR/13C-NMR studies of branched structures in PVC obtained at atmospheric pressure

International Nuclear Information System (INIS)

Braun, D.; Holzer, G.; Hjertberg, T.

1981-01-01

The 1 H-NMR-spectra of raw poly (vinyl cloride) obtained at atmospheric pressure (U-PVC) have revealed the presence of high concentrations of branches. The content of labile chlorine was determined by reaction with phenole in order to estimate the branch points with tertiary chlorine. The branch length of reductively dehalogenated U-PVC by 13 C-NMR analysis have provided evidence for both short chain branches including chloromethyl groups and 2.4-dichloro-n-butyl groups and long chain branching. For a number of U-polymers the total amount of branching ranges from 7.5 to 13.5/1000 C. The 13 C-NMR measurements point to a ratio of methyl/butyl branches of 1:1 and short chains/long chains of 6:1. (orig.)

11B nutation NMR study of powdered borosilicates

International Nuclear Information System (INIS)

Woo, Ae Ja; Yang, Kyung Hwa; Han, Duk Young

1998-01-01

In this work, we applied the 1D 11 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO 2 -B 2 O 3 ). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11 B nutation NMR experiment. The 11 B NMR parameters, quadrupole coupling constants (e 2 qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed

Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet.

Science.gov (United States)

Vennemann, T; Jeong, M; Yoon, D; Magrez, A; Berger, H; Yang, L; Živković, I; Babkevich, P; Rønnow, H M

2018-04-01

We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO 4 with S = 1/2 (Mo 5+ ) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31 P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

Note: Commercial SQUID magnetometer-compatible NMR probe and its application for studying a quantum magnet

Science.gov (United States)

Vennemann, T.; Jeong, M.; Yoon, D.; Magrez, A.; Berger, H.; Yang, L.; Živković, I.; Babkevich, P.; Rønnow, H. M.

2018-04-01

We present a compact nuclear magnetic resonance (NMR) probe which is compatible with a magnet of a commercial superconducting quantum interference device magnetometer and demonstrate its application to the study of a quantum magnet. We employ trimmer chip capacitors to construct an NMR tank circuit for low temperature measurements. Using a magnetic insulator MoOPO4 with S = 1/2 (Mo5+) as an example, we show that the T-dependence of the circuit is weak enough to allow the ligand-ion NMR study of magnetic systems. Our 31P NMR results are compatible with previous bulk susceptibility and neutron scattering experiments and furthermore reveal unconventional spin dynamics.

NMR studies of the helical antiferromagnetic compound EuCo2P2

Science.gov (United States)

Higa, N.; Ding, Q.-P.; Kubota, F.; Uehara, H.; Yogi, M.; Furukawa, Y.; Sangeetha, N. S.; Johnston, D. C.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y.

2018-05-01

In EuCo2P2, 4f electron spins of Eu2+ ions order antiferromagnetically below a Néel temperature TN = 66.5 K . The magnetic structure below TN was reported to be helical with the helix axis along the c-axis from the neutron diffraction study. We report the results of 153Eu, 59Co and 31P nuclear magnetic resonance (NMR) measurements on EuCo2P2 using a single crystal and a powdered sample. In the antiferromagnetic (AFM) state, we succeeded in observing 153Eu, 59Co and 31P NMR spectra in zero magnetic field. The sharp 153Eu zero field NMR (ZF NMR) lines indicate homogeneous Eu ordered moment. The 59Co and 31P ZF NMR spectra showed an asymmetric spectral shape, indicating a distribution of the internal magnetic induction at each nuclear position. The AFM propagation vector k characterizing the helical AFM state can be determined from the internal magnetic induction at Co site. We have determined the model-independent value of the AFM propagation vector k distributed from (0, 0, 0.86)2π/c to (0, 0, 0.73)2π/c, where c is the lattice parameter.

Solid-state NMR of inorganic semiconductors.

Science.gov (United States)

Yesinowski, James P

2012-01-01

Studies of inorganic semiconductors by solid-state NMR vary widely in terms of the nature of the samples investigated, the techniques employed to observe the NMR signal, and the types of information obtained. Compared with the NMR of diamagnetic non-semiconducting substances, important differences often result from the presence of electron or hole carriers that are the hallmark of semiconductors, and whose theoretical interpretation can be involved. This review aims to provide a broad perspective on the topic for the non-expert by providing: (1) a basic introduction to semiconductor physical concepts relevant to NMR, including common crystal structures and the various methods of making samples; (2) discussions of the NMR spin Hamiltonian, details of some of the NMR techniques and strategies used to make measurements and theoretically predict NMR parameters, and examples of how each of the terms in the Hamiltonian has provided useful information in bulk semiconductors; (3) a discussion of the additional considerations needed to interpret the NMR of nanoscale semiconductors, with selected examples. The area of semiconductor NMR is being revitalized by this interest in nanoscale semiconductors, the great improvements in NMR detection sensitivity and resolution that have occurred, and the current interest in optical pumping and spintronics-related studies. Promising directions for future research will be noted throughout.

Contrast-enhanced NMR imaging: animal studies using gadolinium-DTPA complex

International Nuclear Information System (INIS)

Brasch, R.C.; Weinmann, H.J.; Wesbey, G.E.

1984-01-01

Gadolinium (Gd)-DTPA complex was assessed as a nuclear magnetic resonance (NMR) contrast-enhancing agent by experimentally imaging normal and diseased animals. After intravenous injection, Gd-DTPA, a strongly paramagnetic complex by virtue of unpaired electrons, was rapidly excreted into the urine of rats, producing an easily observable contrast enhancement on NMR images in kidney parenchyma and urine. Sterile soft-tissue abscesses demonstrated an obvious rim pattern of enhancement. A focus of radiation-induced brain damage in a canine model was only faintly detectable on spin-echo NMR images before contrast administration; after 0.5 mmol/kg Gd-DTPA administration, the lesion intensity increased from 3867 to 5590. In comparison, the normal brain with an intact blood-brain barrier remained unchanged in NMR characterization. Gd-DTPA is a promising new NMR contrast enhancer for the clinical assessment of renal function, of inflammatory lesions, and of focal disruption of the blood-brain barrier

Moessbauer and NMR study of novel Tin(IV)-lactames

Energy Technology Data Exchange (ETDEWEB)

Kuzmann, Erno; Szalay, Roland; Homonnay, Zoltan, E-mail: homonnay@ludens.elte.hu; Nagy, Sandor [Eoetvoes Lorand University, Institute of Chemistry (Hungary)

2012-03-15

N-tributylstannylated 2-pyrrolidinone was reacted with tributyltin triflate in different molar ratios and the complex formation monitored using {sup 1}H-NMR, {sup 13}C-NMR and {sup 119}Sn Moessbauer spectroscopy. Comparing the carbon NMR and tin Moessbauer results, a reaction scheme is suggested for the complexation which assumes the formation of a simultaneously O- and N-tributylstannylated pyrrolidinone cation. The formation of the only O-stannylated pyrrolidinone is also assumed to account for the non-constant Moessbauer parameters of the two tin environments in the distannylated pyrrolidinone cation when the ratio of tributyltin triflate is increased in the reaction.

11B NMR study of calcium-hexaborides

International Nuclear Information System (INIS)

Mean, B.J.; Lee, K.H.; Kang, K.H.; Lee, Moohee; Rhee, J.S.; Cho, B.K.

2005-01-01

We have performed 11 B nuclear magnetic resonance (NMR) measurements to look for microscopic evidence of the ferromagnetic state in several CaB 6 single crystals. A number of 11 B NMR resonance peaks are observed with the frequency and intensity of those peaks distinctively changing depending on the angle between the crystalline axis and a magnetic field. Analyzing this behavior, we find that the electric field gradient tensor at the boron has its principal axis perpendicular to the six cubic faces with a quadrupole resonance frequency ν Q ∼600kHz. However, the satellite resonances are found to be made of two peaks. Detailed analysis of the four composite satellite peaks confirms that there are two different boron sites with slightly different ν Q 's. This suggests that the boron octahedron cages are locally distorted. However, this distortion is not directly related to ferromagnetism. Even though the magnetization data highlight the ferromagnetic hysteresis, 11 B NMR linewidth and shift data show no clear microscopic evidence of the ferromagnetic state in several different compositions of CaB 6 single crystals

Recent Advances in Targeted and Untargeted Metabolomics by NMR and MS/NMR Methods

Energy Technology Data Exchange (ETDEWEB)

Bingol, Kerem

2018-04-18

Metabolomics has made significant progress in multiple fronts in the last 18 months. This minireview aimed to give an overview of these advancements in the light of their contribution to targeted and untargeted metabolomics. New computational approaches have emerged to overcome manual absolute quantitation step of metabolites in 1D 1H NMR spectra. This provides more consistency between inter-laboratory comparisons. Integration of 2D NMR metabolomics databases under a unified web server allowed very accurate identification of the metabolites that have been catalogued in these databases. For the remaining uncatalogued and unknown metabolites, new cheminformatics approaches have been developed by combining NMR and mass spectrometry. These hybrid NMR/MS approaches accelerated the identification of unknowns in untargeted studies, and now they are allowing to profile ever larger number of metabolites in application studies.

A comparison study of PET, NMR, and CT imaging in cerebral ischemia

International Nuclear Information System (INIS)

Babikian, V.L.; Ford, C.S.; Buonanno, F.S.; Kistler, J.P.; Ackerman, R.H.; Alpert, N.M.; Correia, J.A.; Johnson, K.A.; Buxton, R.B.

1987-01-01

Whether ischemia without infarction produces recognizable changes in relaxation times of ischemic but viable brain is an important, unresolved issue. Therefore, a study was initiated of patients with cerebral ischemia, using positron emission tomography (PET), NMR, and computed tomography (CT) to compare and contrast the pathophysiologic information provided by each and to study the issue of whether cerebral ischemia without infarction can be appreciated by proton NMR imaging. Here the initial results are reported. 4 refs.; 2 figs.; 1 table

NMR data-driven structure determination using NMR-I-TASSER in the CASD-NMR experiment

Energy Technology Data Exchange (ETDEWEB)

Jang, Richard [Huazhong University of Science and Technology, School of Software Engineering (China); Wang, Yan [Huazhong University of Science and Technology, School of Life Science and Technology (China); Xue, Zhidong, E-mail: zdxue@hust.edu.cn [Huazhong University of Science and Technology, School of Software Engineering (China); Zhang, Yang, E-mail: zhng@umich.edu [University of Michigan, Department of Computational Medicine and Bioinformatics (United States)

2015-08-15

NMR-I-TASSER, an adaption of the I-TASSER algorithm combining NMR data for protein structure determination, recently joined the second round of the CASD-NMR experiment. Unlike many molecular dynamics-based methods, NMR-I-TASSER takes a molecular replacement-like approach to the problem by first threading the target through the PDB to identify structural templates which are then used for iterative NOE assignments and fragment structure assembly refinements. The employment of multiple templates allows NMR-I-TASSER to sample different topologies while convergence to a single structure is not required. Retroactive and blind tests of the CASD-NMR targets from Rounds 1 and 2 demonstrate that even without using NOE peak lists I-TASSER can generate correct structure topology with 15 of 20 targets having a TM-score above 0.5. With the addition of NOE-based distance restraints, NMR-I-TASSER significantly improved the I-TASSER models with all models having the TM-score above 0.5. The average RMSD was reduced from 5.29 to 2.14 Å in Round 1 and 3.18 to 1.71 Å in Round 2. There is no obvious difference in the modeling results with using raw and refined peak lists, indicating robustness of the pipeline to the NOE assignment errors. Overall, despite the low-resolution modeling the current NMR-I-TASSER pipeline provides a coarse-grained structure folding approach complementary to traditional molecular dynamics simulations, which can produce fast near-native frameworks for atomic-level structural refinement.

Studies on Photodarkening Effect in Glassy As2S3 Using High Field NMR

Science.gov (United States)

Hari, Parameswar; Su, Tining; Taylor, Craig; Reyes, Arneil; Kuhns, Phil; Moulton, William; Sullivan, N. S.

2001-03-01

Photodarkening, or the shift of the optical absorption edge to smaller energies after excitation with light whose energy is near that of the optical band edge, has been studied in many chalcogenide glasses for many years. Recently we have conducted nuclear magnetic resonance (NMR) studies of 75As in glassy As2S3 at 17T . We compared the 75As NMR lineshape in glassy As2S3 before and after irradiation at 77K. After irradiation at 514.5 nm for 230 hours with 170 mW/cm2 there is a subtle change in the NMR lineshape. This change is reversible on annealing at 200 C for 1.75 hours. We will discuss the implications of this result based on NMR lineshape analysis using an exact solution of the spin 3/2 Hamiltonian

Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

Directory of Open Access Journals (Sweden)

Yang Liu

2016-01-01

Full Text Available Quantitative nuclear magnetic resonance (qNMR is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR and only a few fluorine qNMR (19F qNMR were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes.

Backbone dynamics of free barnase and its complex with barstar determined by 15N NMR relaxation study

International Nuclear Information System (INIS)

Sahu, Sarata C.; Bhuyan, Abani K.; Udgaonkar, Jayant B.; Hosur, R.V.

2000-01-01

Backbone dynamics of uniformly 15 N-labeled free barnase and its complex with unlabelled barstar have been studied at 40 deg. C, pH 6.6, using 15 N relaxation data obtained from proton-detected 2D { 1 H}- 15 N NMR spectroscopy. 15 N spin-lattice relaxation rate constants (R 1 ), spin-spin relaxation rate constants (R 2 ), and steady-state heteronuclear { 1 H}- 15 N NOEs have been measured at a magnetic field strength of 14.1 Tesla for 91 residues of free barnase and for 90 residues out of a total of 106 in the complex (excluding three prolines and the N-terminal residue) backbone amide 15 N sites of barnase. The primary relaxation data for both the cases have been analyzed in the framework of the model-free formalism using both isotropic and axially symmetric models of the rotational diffusion tensor. As per the latter, the overall rotational correlation times (τ m ) are 5.0 and 9.5 ns for the free and complexed barnase, respectively. The average order parameter is found to be 0.80 for free barnase and 0.86 for the complex. However, the changes are not uniform along the backbone and for about 5 residues near the binding interface there is actually a significant decrease in the order parameters on complex formation. These residues are not involved in the actual binding. For the residues where the order parameter increases, the magnitudes vary significantly. It is observed that the complex has much less internal mobility, compared to free barnase. From the changes in the order parameters, the entropic contribution of NH bond vector motion to the free energy of complex formation has been calculated. It is apparent that these motions cause significant unfavorable contributions and therefore must be compensated by many other favorable contributions to effect tight complex formation. The observed variations in the motion and their different locations with regard to the binding interface may have important implications for remote effects and regulation of the enzyme

A Field Study of NMR Logging to Quantify Petroleum Contamination in Subsurface Sediments

Science.gov (United States)

Fay, E. L.; Knight, R. J.; Grunewald, E. D.

2016-12-01

Nuclear magnetic resonance (NMR) measurements are directly sensitive to hydrogen-bearing fluids including water and petroleum products. NMR logging tools can be used to detect and quantify petroleum hydrocarbon contamination in the sediments surrounding a well or borehole. An advantage of the NMR method is that data can be collected in both cased and uncased holes. In order to estimate the volume of in-situ hydrocarbon, there must be sufficient contrast between either the relaxation times (T2) or the diffusion coefficients (D) of water and the contaminant. In a field study conducted in Pine Ridge, South Dakota, NMR logging measurements were used to investigate an area of hydrocarbon contamination from leaking underground storage tanks. A contaminant sample recovered from a monitoring well at the site was found to be consistent with a mixture of gasoline and diesel fuel. NMR measurements were collected in two PVC-cased monitoring wells; D and T2 measurements were used together to detect and quantify contaminant in the sediments above and below the water table at both of the wells. While the contrast in D between the fluids was found to be inadequate for fluid typing, the T2 contrast between the contaminant and water in silt enabled the estimation of the water and contaminant volumes. This study shows that NMR logging can be used to detect and quantify in-situ contamination, but also highlights the importance of sediment and contaminant properties that lead to a sufficiently large contrast in T2 or D.

'In vivo' and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study

International Nuclear Information System (INIS)

Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R.

1995-01-01

This work has developed a study on transgenic plants using two different techniques of nuclear magnetic resonance, in vivo NMR and high resolution NMR. In order to understand the gene mutations and characterize the plants constituents, NMR spectral data were analysed and discussed, then the results were presented

High resolution NMR spectroscopy of synthetic polymers in bulk

International Nuclear Information System (INIS)

Komorski, R.A.

1986-01-01

The contents of this book are: Overview of high-resolution NMR of solid polymers; High-resolution NMR of glassy amorphous polymers; Carbon-13 solid-state NMR of semicrystalline polymers; Conformational analysis of polymers of solid-state NMR; High-resolution NMR studies of oriented polymers; High-resolution solid-state NMR of protons in polymers; and Deuterium NMR of solid polymers. This work brings together the various approaches for high-resolution NMR studies of bulk polymers into one volume. Heavy emphasis is, of course, given to 13C NMR studies both above and below Tg. Standard high-power pulse and wide-line techniques are not covered

NMR study of structure of lanthanide complexes in solution

International Nuclear Information System (INIS)

Choppin, G.R.

1976-01-01

The diagnostic value PMR studies of diamagnetic lanthanide complexes to define the nature of the species in the lanthanide-pyruvate system is discussed. The use of NMR spectra of both diamagnetic and paramagnetic lanthanide complexes to obtain detailed structural information is reviewed

1D AND 2D NMR STUDIES OF BENZYL O–VANILLIN

Directory of Open Access Journals (Sweden)

Mohammed Hadi Al–Douh

2010-06-01

Full Text Available The reaction of o-vanillin A with benzyl bromide B2 in acetone as the solvent and K2CO3 as a base in the presence of tetra-n-butylammonium iodide (TBAI as catalyst formed benzyl o-vanillin, C. The complete assignments of C using PROTON, APT, DEPT-135, COSY, NOESY, HMQC and HMBC NMR in both CDCl3 and acetone-d6 are discussed, and the coupling constants J are reported in Hertz (Hz.     Keywords: 1H NMR; 13C NMR; 2D NMR; Benzyl o-Vanillin

Determinação por RMN das configurações relativas e conformações de alcalóides oxindólicos isolados de Uncaria guianensis

Directory of Open Access Journals (Sweden)

Carbonezi Carlos Alberto

2004-01-01

Full Text Available Phytochemical studies with leaves of Uncaria guianensis resulted in the isolation of the oxindole alkaloids isomitraphylline (1, 3-isoajmalicine (2 mitraphylline (3, and isomitraphylinic acid (4. Structural assignments of these alkaloids, including relative configurations and conformations, were performed through spectral data and physical properties. 1D and 2D homonuclear and heteronuclear NMR spectroscopy was a valuable tool for the establishment of the relative stereochemistry of those compounds.

Atom-dimer scattering in a heteronuclear mixture with a finite intraspecies scattering length

Science.gov (United States)

Gao, Chao; Zhang, Peng

2018-04-01

We study the three-body problem of two ultracold identical bosonic atoms (denoted by B ) and one extra atom (denoted by X ), where the scattering length aB X between each bosonic atom and atom X is resonantly large and positive. We calculate the scattering length aad between one bosonic atom and the shallow dimer formed by the other bosonic atom and atom X , and investigate the effect induced by the interaction between the two bosonic atoms. We find that even if this interaction is weak (i.e., the corresponding scattering length aB B is of the same order of the van der Waals length rvdW or even smaller), it can still induce a significant effect for the atom-dimer scattering length aad. Explicitly, an atom-dimer scattering resonance can always occur when the value of aB B varies in the region with | aB B|≲ rvdW . As a result, both the sign and the absolute value of aad, as well as the behavior of the aad-aB X function, depends sensitively on the exact value of aB B. Our results show that, for a good quantitative theory, the intraspecies interaction is required to be taken into account for this heteronuclear system, even if this interaction is weak.

A combined NMR and XRD study of AFI and AEL type molecular sieves

NARCIS (Netherlands)

Peeters, M.P.J.; Ven, van de L.J.M.; Haan, de J.W.; Hooff, van J.H.C.

1993-01-01

Calcined dehydrated AlPO4-5 was studied by x-ray powder diffraction, 31P MAS, and 27Al double-resonance (DOR) NMR. Three crystallog. different sites can be distinguished in the structure of dehydrated AlPO4-5 in the ratio 1:1:1. The obsd. splitting of the NMR spectra is correlated to the line width

53Cr NMR study of CuCrO2 multiferroic

Science.gov (United States)

Smol'nikov, A. G.; Ogloblichev, V. V.; Verkhovskii, S. V.; Mikhalev, K. N.; Yakubovskii, A. Yu.; Kumagai, K.; Furukawa, Y.; Sadykov, A. F.; Piskunov, Yu. V.; Gerashchenko, A. P.; Barilo, S. N.; Shiryaev, S. V.

2015-11-01

The magnetically ordered phase of the CuCrO2 single crystal has been studied by the nuclear magnetic resonance (NMR) method on 53Cr nuclei in the absence of an external magnetic field. The 53Cr NMR spectrum is observed in the frequency range νres = 61-66 MHz. The shape of the spectrum depends on the delay tdel between pulses in the pulse sequence τπ/2- t del-τπ- t del-echo. The spin-spin and spin-lattice relaxation times have been measured. Components of the electric field gradient, hyperfine fields, and the magnetic moment on chromium atoms have been estimated.

Two- and three-dimensional proton NMR studies of apo-neocarzinostatin

International Nuclear Information System (INIS)

Xiaolian Gao; Burkhart, W.

1991-01-01

Neocarzinostatin (NCS) is an antitumor protein from Streptomyces carzinostaticus that is identical in apo-protein sequence with mitomalcin (MMC) from Streptomyces malayensis. The authors describe the use of apo-NCS as a model system for applying combined two-and three-dimensional (2D and 3D) proton NMR spectroscopy to the structure determination of proteins without isotope labeling. Strategies aimed at accurately assigning overlapped 2D cross-peaks by using semiautomated combined 2D and 3D data analysis are developed. Using this approach, they have assigned 99% of the protons, including those of the side chains, and identified about 1,270 intra- and interresidue proton-proton interactions (fixed distances are not included) in apo-NCS. Comparing these results with those reported recently on 2D NMR studies of apo-NCS demonstrated advantages of proton 3D NMR spectroscopy in protein spectral assignments. They are able to obtain more complete proton resonance and secondary structural assignments and find several misassignments in the earlier report. Strategies utilized in this work should be useful for developing automation procedures for spectral assignments

NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

Directory of Open Access Journals (Sweden)

Fen Yue

2018-04-01

Full Text Available Hydrothermal carbonization (HTC is a valuable approach to convert furfural residue (FR into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H13C HSQC etc. especially 1D selective gradient total correlation spectroscopy (TOCSY NMR were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies. Keywords: NMR, Hydrothermal carbonization, Furfural residue, Stock process water

Impact of opal nanoconfinement on electronic properties of sodium particles: NMR studies

Energy Technology Data Exchange (ETDEWEB)

Charnaya, E.V., E-mail: charnaya@live.com [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Institute of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Lee, M.K. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); MoST Instrument Center at NCKU, Tainan, 70101 Taiwan (China); Chang, L.J. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Kumzerov, Yu.A.; Fokin, A.V. [A.F. Ioffe Physico-Technical Institute RAS, St. Petersburg, 194021 (Russian Federation); Samoylovich, M.I. [Moscow Institute of Physics and Technology, Moscow, 141700 (Russian Federation); Bugaev, A.S. [CSR Institute of Technology “Technomash”, Moscow, 121108 (Russian Federation)

2015-03-20

The {sup 23}Na Knight shift of NMR line which is highly correlated with the electron spin susceptibility and density of states at the Fermi level was studied for the sodium loaded opal. The measurements were carried out within a temperature range from 100 to 400 K for solid and melted confined sodium nanoparticles. The NMR line below 305 K was a singlet with the Knight shift reduced compared to that in bulk. Above this temperature the NMR line split reproducibly into two components with opposite trends in the Knight shift temperature dependences which evidenced a nanoconfinement-induced transformation and heterogeneity in the electron system. The findings were suggested to be related to changes in the topology of the Fermi surface.

Application of unsymmetrical indirect covariance NMR methods to the computation of the (13)C (15)N HSQC-IMPEACH and (13)C (15)N HMBC-IMPEACH correlation spectra.

Science.gov (United States)

Martin, Gary E; Hilton, Bruce D; Irish, Patrick A; Blinov, Kirill A; Williams, Antony J

2007-10-01

Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. (c) 2007 John Wiley & Sons, Ltd.

Synergistic Applications of MD and NMR for the Study of Biological Systems

Directory of Open Access Journals (Sweden)

Olivier Fisette

2012-01-01

same time, theoretical and computational approaches gain in reliability and their field of application widens. In this short paper, we discuss recent advances in the areas of solution nuclear magnetic resonance (NMR spectroscopy and molecular dynamics (MD simulations that were made possible by the combination of both methods, that is, through their synergistic use. We present the main NMR observables and parameters that can be computed from simulations, and how they are used in a variety of complementary applications, including dynamics studies, model-free analysis, force field validation, and structural studies.

Molecular motion of micellar solutes: a 13C NMR relaxation study

International Nuclear Information System (INIS)

Stark, R.E.; Kasakevich, M.L.; Granger, J.W.

1982-01-01

A series of simple NMR relaxation experiments have been performed on nitrobenzene and aniline dissolved in the ionic detergents sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB). Using 13 C relaxation rates at various molecular sites, and comparing data obtained in organic media with those for micellar solutions, the viscosity at the solubilization site was estimated and a detailed picture of motional restrictions imposed by the micellar enviroment was derived. Viscosities of 8 to 17 cp indicate a rather fluid environment for solubilized nitrobenzene; both additives exhibit altered motional preferences in CTAB solutions only. As an aid in interpretation of the NMR data, quasi-elastic light scattering and other physical techniques have been used to evaluate the influence of organic solutes on micellar size and shape. The NMR methods are examined critically in terms of their general usefulness for studies of solubilization in detergent micelles. 48 references

The pro region required for folding of carboxypeptidase Y is a partially folded domain with little regular structural core

DEFF Research Database (Denmark)

Sørensen, P; Winther, Jakob R.; Kaarsholm, N C

1993-01-01

The pro region of carboxypeptidase Y (CPY) from yeast is necessary for the correct folding of the enzyme [Winther, J. R., & Sørensen P. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 9330-9334]. Using fluorescence, circular dichroism, and heteronuclear NMR analyses, it is demonstrated that the isolated...

CcpNmr AnalysisAssign: a flexible platform for integrated NMR analysis

International Nuclear Information System (INIS)

Skinner, Simon P.; Fogh, Rasmus H.; Boucher, Wayne; Ragan, Timothy J.; Mureddu, Luca G.; Vuister, Geerten W.

2016-01-01

NMR spectroscopy is an indispensably powerful technique for the analysis of biomolecules under ambient conditions, both for structural- and functional studies. However, in practice the complexity of the technique has often frustrated its application by non-specialists. In this paper, we present CcpNmr version-3, the latest software release from the Collaborative Computational Project for NMR, for all aspects of NMR data analysis, including liquid- and solid-state NMR data. This software has been designed to be simple, functional and flexible, and aims to ensure that routine tasks can be performed in a straightforward manner. We have designed the software according to modern software engineering principles and leveraged the capabilities of modern graphics libraries to simplify a variety of data analysis tasks. We describe the process of backbone assignment as an example of the flexibility and simplicity of implementing workflows, as well as the toolkit used to create the necessary graphics for this workflow. The package can be downloaded from www.ccpn.ac.uk/v3-software/downloads http://www.ccpn.ac.uk/v3-software/downloads and is freely available to all non-profit organisations.

CcpNmr AnalysisAssign: a flexible platform for integrated NMR analysis

Energy Technology Data Exchange (ETDEWEB)

Skinner, Simon P.; Fogh, Rasmus H. [University of Leicester, Department of Molecular and Cell Biology, Leicester Institute for Structural- and Chemical Biology (United Kingdom); Boucher, Wayne [University of Cambridge, Department of Biochemistry (United Kingdom); Ragan, Timothy J.; Mureddu, Luca G.; Vuister, Geerten W., E-mail: gv29@le.ac.uk [University of Leicester, Department of Molecular and Cell Biology, Leicester Institute for Structural- and Chemical Biology (United Kingdom)

2016-10-15

NMR spectroscopy is an indispensably powerful technique for the analysis of biomolecules under ambient conditions, both for structural- and functional studies. However, in practice the complexity of the technique has often frustrated its application by non-specialists. In this paper, we present CcpNmr version-3, the latest software release from the Collaborative Computational Project for NMR, for all aspects of NMR data analysis, including liquid- and solid-state NMR data. This software has been designed to be simple, functional and flexible, and aims to ensure that routine tasks can be performed in a straightforward manner. We have designed the software according to modern software engineering principles and leveraged the capabilities of modern graphics libraries to simplify a variety of data analysis tasks. We describe the process of backbone assignment as an example of the flexibility and simplicity of implementing workflows, as well as the toolkit used to create the necessary graphics for this workflow. The package can be downloaded from www.ccpn.ac.uk/v3-software/downloads http://www.ccpn.ac.uk/v3-software/downloads and is freely available to all non-profit organisations.

15N NMR studies of layered nitride superconductor LixZrNCl

International Nuclear Information System (INIS)

Tou, H.; Oshiro, S.; Kotegawa, H.; Taguchi, Y.; Kishiume, Y.; Kasahara, Y.; Iwasa, Y.

2010-01-01

NMR measurements were carried out on pristine ZrNCl and Li x ZrNCl. From the 15 N-Knight shift study, the isotropic Knight shift, the traceless chemical (orbital) shift tensor and the traceless Knight shift tensor were determined as K iso = -71 ppm, (σ 1 , σ 2 , σ 3 ) = (-55, -55, 110) ppm and (K 1 , K 2 , K 3 ) = (48, 48, -96) ppm, respectively. In the superconducting state, the fractional change of the 15 N NMR shift for H-parallel ab was observed, evidencing that the pairing symmetry is a spin-singlet state.

Applications of one-dimensional or two-dimensional nuclear magnetic resonance to the structural and conformational study of oligosaccharides. Design and adjustment of new techniques

International Nuclear Information System (INIS)

Berthault, Patrick

1988-01-01

Oligosaccharides are natural compounds of huge importance as they intervene in all metabolic processes of cell life. Before the determination of structure-activity relationships, a precise knowledge of their chemical nature is therefore required. Thus, this research thesis aims at describing various experiments of high resolution nuclear magnetic resonance (NMR), and at demonstrating their applications on four oligosaccharides. After a brief description of NMR principles by using a conventional description and also a formalism derived from quantum mechanics, the author outlines the weaknesses of old NMR techniques, and introduces new techniques by using scalar couplings, by processing magnetization transfers with one-dimensional hetero-nuclear experiments. General principles of two-dimensional experiments are then presented and developed in terms of simple correlations, multiple correlations, correlations via double quantum coherencies. Experiments with light water are then described, and different experiments are performed to determine the structure and conformation of each unit. Bipolar interactions are then addressed to highlight proximities between atoms [fr

An NMR Protonation Study of Metal Diethylenetriaminepentaacetic Acid Complexes.

Science.gov (United States)

Letkeman, Peter

1979-01-01

This experiment is suitable for an integrated laboratory course for senior chemistry majors. It introduces the student to a study of the relative basicity of different proton accepting sites. It serves as an opportunity to learn about nmr techniques and could extend to infrared, as well. (BB)

Structural studies of SpoIIAA using NMR

International Nuclear Information System (INIS)

Comfort, D.M.

1998-01-01

The protein SpoIIAA participates, via phosphorylation and dephosphorylation, in the four-component system that regulates the sporulation sigma factor e. Differential gene expression depends on specialised transcription factors called sigma factors, which direct the RNA polymerase to transcribe specific genes in one or other of the two chambers at various stages of sporulation. The first sporulation-specific sigma factor to be activated is 4 transcription that depends on σ F is essential for the remaining sigma factors to become active in turn. Early in sporulation SpoIIAA is in the phosphorylated state (SpoIIAA-P), as a result of the activity of the ATP-dependent protein kinase, SpoIIAB. About 80 minutes after the initiation of sporulation a specific phosphatase, SpoIIE, begins to hydrolyse SpoIIAA-P, and the resulting SpoIIAA again becomes a substrate for SpoIIAB. SpoIIAB is also an anti-sigma factor which in its free form inhibits a F by binding to it. Competition by SpoIIAA (the anti-anti-sigma factor) for binding to SpoIIAB releases e activity. The three-dimensional structure of SpoIIAA has been determined using high resolution NMR. SpoIIAA has a novel fold, composed of a-helices and P-strand elements. The structural differences between SpoIIAA and its inactive form, SpoIIAA-P, were also investigated by NMR. Tentative evidence points to the observation that phosphorylation of SpoIIAA results in a minor conformational change near the site of phosphorylation, which interferes with the hydrophobic interaction between SpoIIAA and SpoIIAB. Further NMR studies helped to predict the location of SpoIIAA-, GTP-, and ATP-binding sites on the SpoIIAA structure. In addition, the automated iterative NOE assignment algorithm, ARIA, was used to obtain additional NOE-based distance constraints and to calculate a refined structure. (author)

Structural studies of SpoIIAA using NMR

Energy Technology Data Exchange (ETDEWEB)

Comfort, D.M

1998-07-01

The protein SpoIIAA participates, via phosphorylation and dephosphorylation, in the four-component system that regulates the sporulation sigma factor e. Differential gene expression depends on specialised transcription factors called sigma factors, which direct the RNA polymerase to transcribe specific genes in one or other of the two chambers at various stages of sporulation. The first sporulation-specific sigma factor to be activated is 4 transcription that depends on {sigma}{sup F} is essential for the remaining sigma factors to become active in turn. Early in sporulation SpoIIAA is in the phosphorylated state (SpoIIAA-P), as a result of the activity of the ATP-dependent protein kinase, SpoIIAB. About 80 minutes after the initiation of sporulation a specific phosphatase, SpoIIE, begins to hydrolyse SpoIIAA-P, and the resulting SpoIIAA again becomes a substrate for SpoIIAB. SpoIIAB is also an anti-sigma factor which in its free form inhibits a F by binding to it. Competition by SpoIIAA (the anti-anti-sigma factor) for binding to SpoIIAB releases e activity. The three-dimensional structure of SpoIIAA has been determined using high resolution NMR. SpoIIAA has a novel fold, composed of a-helices and P-strand elements. The structural differences between SpoIIAA and its inactive form, SpoIIAA-P, were also investigated by NMR. Tentative evidence points to the observation that phosphorylation of SpoIIAA results in a minor conformational change near the site of phosphorylation, which interferes with the hydrophobic interaction between SpoIIAA and SpoIIAB. Further NMR studies helped to predict the location of SpoIIAA-, GTP-, and ATP-binding sites on the SpoIIAA structure. In addition, the automated iterative NOE assignment algorithm, ARIA, was used to obtain additional NOE-based distance constraints and to calculate a refined structure. (author)

NMR study of hyper-polarized 129Xe and applications to liquid-phase NMR experiments

International Nuclear Information System (INIS)

Marion, D.

2008-07-01

In liquid samples where both nuclear polarization and spin density are strong, the magnetization dynamics, which can be analysed by NMR (nuclear magnetic resonance) methods, is deeply influenced by the internal couplings induced by local dipolar fields. The present thesis describes some of the many consequences associated to the presence in the sample of concentrated xenon hyper-polarized by an optical pumping process. First, we deal with the induced modifications in frequency and line width of the proton and xenon spectra, then we present the results of SPIDER, a coherent polarization transfer experiment designed to enhance the polarization of protons, in order to increase their NMR signal level. A third part is dedicated to the description of the apparition of repeated chaotic maser emissions by un unstable xenon magnetization coupled to the detection coil tuned at the xenon Larmor frequency (here 138 MHz). In the last part, we present a new method allowing a better tuning of any NMR detection probe and resulting in sensible gains in terms of sensitivity and signal shaping. Finally, we conclude with a partial questioning of the classical relaxation theory in the specific field of highly polarized and concentrated spin systems in a liquid phase. (author)

Use of 15N reverse gradient two-dimensional nuclear magnetic resonance spectroscopy to follow metabolic activity in Nicotiana plumbaginifolia cell-suspension cultures.

Science.gov (United States)

Mesnard, F; Azaroual, N; Marty, D; Fliniaux, M A; Robins, R J; Vermeersch, G; Monti, J P

2000-02-01

Nitrogen metabolism was monitored in suspension cultured cells of Nicotiana plumbaginifolia Viv. using nuclear magnetic resonance (NMR) spectroscopy following the feeding of (15NH4)2SO4 and K15NO3. By using two-dimensional 15N-1H NMR with heteronuclear single-quantum-coherence spectroscopy and heteronuclear multiple-bond-coherence spectroscopy sequences, an enhanced resolution of the incorporation of 15N label into a range of compounds could be detected. Thus, in addition to the amino acids normally observed in one-dimensional 15N NMR (glutamine, aspartate, alanine), several other amino acids could be resolved, notably serine, glycine and proline. Furthermore, it was found that the peak normally assigned to the non-protein amino-acid gamma-aminobutyric acid in the one-dimensional 15N NMR spectrum was resolved into a several components. A peak of N-acetylated compounds was resolved, probably composed of the intermediates in arginine biosynthesis, N-acetylglutamate and N-acetylornithine and, possibly, the intermediate of putrescine degradation into gamma-aminobutyric acid, N-acetylputrescine. The occurrence of 15N-label in agmatine and the low detection of labelled putrescine indicate that crucial intermediates of the pathway from glutamate to polyamines and/or the tobacco alkaloids could be monitored. For the first time, labelling of the peptide glutathione and of the nucleotide uridine could be seen.

Optical pumping and xenon NMR

International Nuclear Information System (INIS)

Raftery, M.D.

1991-11-01

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129 Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131 Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen

NMR spectroscopic studies of membrane-bound biological systems

International Nuclear Information System (INIS)

Hohlweg, W.

2013-01-01

In the course of this thesis, biological NMR spectroscopy was employed in studying membrane-bound peptides and proteins, for which structural information is still comparatively hard to obtain. Initial work focused on various model peptides bound to membrane-mimicking micelles, studying the protonation state of arginine in a membrane environment. Strong evidence for a cation-π complex was found in TM7, a peptide which forms the seventh transmembrane helix of subunit a of the vacuolar-type H+-ATPase (V-ATPase). V-ATPase is a physiologically highly relevant proton pump, which is present in intracellular membranes of all eukaryotic organisms, as well as the plasma membrane of several specialized cells. Loss of functional V-ATPase is associated with human diseases such as osteopetrosis, distal renal tubular acidosis or the spreading of cancer. V-ATPase is considered a potential drug target in the treatment of osteoporosis and cancer, or in the development of novel contraceptives. Results from NMR solution structure determination, NMR titration experiments, paramagnetic relaxation enhancement experiments and tryptophan fluorescence spectroscopy confirm the existence of a buried cation-? complex formed between arginine residue R735, which is essential for proton transport, and neighbouring tryptophan and tyrosine residues. In vivo experiments in the yeast Saccharomyces cerevisiae using selective growth tests and fluorescence microscopy showed that formation of the cation-π complex is essential for V-ATPase function. Deletion of both aromatic residues, as well as only the one tryptophan residue leads to growth defects and inability to maintain vacuolar pH homeostasis. These findings shine new light on the still elusive mechanism of proton transport in V-ATPase, and show that arginine R735 may be directly involved in proton transfer across the membrane. (author) [de

Studies of metal-biomolecule systems in liquids with beta-detected NMR

CERN Document Server

Walczak, Michal

2017-01-01

My internship took place within a small research team funded via the European Research Council (ERC Starting Grant: Beta-Drop NMR) at ISOLDE. It was devoted to laser spin-polarization and beta-detected NMR techniques and their future applications in chemistry and biology. I was involved in the design and tests of the beta-NMR spectrometer which will be used in the upcoming experiments. In this way I have been exposed to many topics in physics (atomic and nuclear physics), experimental techniques (vacuum technology, lasers, beta detectors, electronics, DAQ software), as well as chemistry and biology (NMR on metal ions, metal ion binding to biomolecules, quantum chemistry calculations).

GC-MS and NMR analysis of the bioactive compounds from the crude extracts of Waltheria indica and the histopathological changes induced in albino rats challenged with Naja nigricollis venom

Directory of Open Access Journals (Sweden)

Philip Ilani

2016-05-01

Full Text Available Objective: To develop a characteristic fingerprint of the different chemical compounds of plant by gas chromatography-mass spectrometer (GC-MS and nuclear magnetic resonance (NMR analysis and assess the effect of the crude extract on histological changes induced in Naja nigricollis (N. nigricollis envenomed albino rats. Methods: The coarsely powdered Waltheria indica (W. indica whole plant material was extracted using 70% methanol. GC-MS analysis was carried out using a Shimadzu GC-MS QP 2010 plus system of gas chromatography interfaced to a mass spectrometer. The identification of components was based on National Institute of Standard and Technology-08 and Willey-8 libraries. Hydrogen-NMR spectra of the extracts was performed using Bruker Biospin Avance 400-MHz NMR spectrophotometer with a 5 mm broad inverse probe head, equipped with shielded z-gradient accessories and C-13 NMR hetero-nuclear single quantum correction was carried out using the Brucker’s standard pulse library. The efficacy of the crude extract of W. indica whole plant was tested and the lesions induced in the liver, brain and kidney of albino rats challenged with N. nigricollis were analyzed by light microscopy. Results: The identification of the bioactive compounds from W. indica by GC-MS analysis revealed 41 peaks. A total of 38 compounds were identified with majority having important pharmacological activities that included anti-microbial, anti-cancer, anti-oxidant antiinflammatory, anti-allergenic, anti-ageing, anti-arthritic, larvicidal, anti-convulsant and herbicidal activities. C-13 and hydrogen-NMR analysis of W. indica elucidated key bioactive compounds in the whole plant that were consistent with the classes of bioactive compounds detected by GC-MS analysis. The efficacy of the crude extract of W. indica whole plant in ameliorating histopathological lesions induced in the liver, brain and kidney of albino rats challenged with N. nigricollis venom revealed the

GC-MS and NMR analysis of the bioactive compounds from the crude extracts ofWaltheria indica and the histopathological changes induced in albino rats challenged withNaja nigricollis venom

Institute of Scientific and Technical Information of China (English)

Philip Ilani; Nicholas Ajodo; Folashade Adewusi; Samirat Yakubu; Victor Yakubu Cosmos; Ache Eunice; Atonila Kayode Ezekiel; Oshiedu Sarah; Emmanuel Amlabu

2016-01-01

Objective:To develop a characteristic fingerprint of the different chemical compounds of plant by gas chromatography-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR) analysis and assess the effect of the crude extract on histological changes induced inNaja nigricollis(N. nigricollis)envenomed albino rats. Methods: The coarsely powderedWaltheria indica (W. indica) whole plant material was extracted using 70% methanol.GC-MS analysis was carried out using a ShimadzuGC-MS QP 2010 plus system of gas chromatography interfaced to a mass spectrometer. The identification of components was based on National Institute of Standard and Technology-08 and Willey-8 libraries. Hydrogen-NMR spectra of the extracts was performed using Bruker Biospin Avance 400-MHzNMR spectrophotometer with a 5 mm broad inverse probe head, equipped with shielded z-gradient accessories andC-13 NMR hetero-nuclear single quantum correction was carried out using the Brucker’s standard pulse library. The efficacy of the crude extract ofW. indica whole plant was tested and the lesions induced in the liver, brain and kidney of albino rats challenged withN. nigricollis were analyzed by light microscopy. Results:The identification of the bioactive compounds fromW. indica byGC-MS analysis revealed 41 peaks. A total of 38 compounds were identified with majority having important pharmacological activities that included anti-microbial, anti-cancer, anti-oxidant anti-inflammatory, anti-allergenic, anti-ageing, anti-arthritic, larvicidal, anti-convulsant and herbicidal activities.C-13 and hydrogen-NMR analysis ofW. indica elucidated key bioactive compounds in the whole plant that were consistent with the classes of bioactive compounds detected byGC-MS analysis. The efficacy of the crude extract ofW. indica whole plant in ameliorating histopathological lesions induced in the liver, brain and kidney of albino rats challenged withN. nigricollis venom revealed the abrogation of tissue degeneration when

1H-NMR, 1H-NMR T2-edited, and 2D-NMR in bipolar disorder metabolic profiling.

Science.gov (United States)

Sethi, Sumit; Pedrini, Mariana; Rizzo, Lucas B; Zeni-Graiff, Maiara; Mas, Caroline Dal; Cassinelli, Ana Cláudia; Noto, Mariane N; Asevedo, Elson; Cordeiro, Quirino; Pontes, João G M; Brasil, Antonio J M; Lacerda, Acioly; Hayashi, Mirian A F; Poppi, Ronei; Tasic, Ljubica; Brietzke, Elisa

2017-12-01

The objective of this study was to identify molecular alterations in the human blood serum related to bipolar disorder, using nuclear magnetic resonance (NMR) spectroscopy and chemometrics. Metabolomic profiling, employing 1 H-NMR, 1 H-NMR T 2 -edited, and 2D-NMR spectroscopy and chemometrics of human blood serum samples from patients with bipolar disorder (n = 26) compared with healthy volunteers (n = 50) was performed. The investigated groups presented distinct metabolic profiles, in which the main differential metabolites found in the serum sample of bipolar disorder patients compared with those from controls were lipids, lipid metabolism-related molecules (choline, myo-inositol), and some amino acids (N-acetyl-L-phenyl alanine, N-acetyl-L-aspartyl-L-glutamic acid, L-glutamine). In addition, amygdalin, α-ketoglutaric acid, and lipoamide, among other compounds, were also present or were significantly altered in the serum of bipolar disorder patients. The data presented herein suggest that some of these metabolites differentially distributed between the groups studied may be directly related to the bipolar disorder pathophysiology. The strategy employed here showed significant potential for exploring pathophysiological features and molecular pathways involved in bipolar disorder. Thus, our findings may contribute to pave the way for future studies aiming at identifying important potential biomarkers for bipolar disorder diagnosis or progression follow-up.

Positron annihilation and 129Xe NMR studies of free volume in polymers

International Nuclear Information System (INIS)

Nagasaka, Bunsow; Eguchi, Taro; Nakayama, Hirokazu; Nakamura, Nobuo; Ito, Yasuo

2000-01-01

The existence and the average size of free volume in bisphenol-A polycarbonate (PC), low-density polyethylene (LDPE), poly (2,6-dimethyl-phenylene oxide)(PPO), and polytetrafluoroethylene (PTFE) were studied by positron annihilation and 129 Xe NMR measurements. The 129 Xe NMR chemical shifts for xenon adsorbed in the polymers indicated that the average pore size of the free volume increased in the following order: PC, LDPE, PPO, and PTFE. This order of the pore size of the free volume agrees well with that estimated from the longest lifetime (τ 3 ) of ortho-positronium formed in the polymers. The unique correlation that δ -1 ∝ r is established between the 129 Xe NMR chemical shift (δ) and the pore size (r), which is deduced from the positron annihilation measurements.

NMR-based milk metabolomics

DEFF Research Database (Denmark)

Sundekilde, Ulrik; Larsen, Lotte Bach; Bertram, Hanne Christine S.

2013-01-01

and processing capabilities of bovine milk is closely associated to milk composition. Metabolomics is ideal in the study of the low-molecular-weight compounds in milk, and this review focuses on the recent nuclear magnetic resonance (NMR)-based metabolomics trends in milk research, including applications linking...... compounds. Furthermore, metabolomics applications elucidating how the differential regulated genes affects milk composition are also reported. This review will highlight the recent advances in NMR-based metabolomics on milk, as well as give a brief summary of when NMR spectroscopy can be useful for gaining...

Solid state NMR study of cumbaru flour

International Nuclear Information System (INIS)

Nogueira, Jose S.; Bathista, Andre L.B.S.; Silva, Emerson O.; Priante Filho, Nicolau; Tavares, Maria I.B.

2001-01-01

The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13 C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T 1 H ρ). Knowing that the chemical structure and molecular dynamic are extremely necessary route to obtain information on the polysaccharides, this work contributes to the classification of the seed containing in the cumbaru fruit to get response on its application. To obtain the initial responses for our purposes some solid state NMR techniques were chosen. The CPMAS 13 C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13 C NMR spectrum showed the presence of domains with distinct molecular mobility, because these domains will differ basically in the distribution size and chain packing. The variable contact time experiment was used to analyse the distribution form of 13 C decays, which give us more information about sample heterogeneity. The T 1 H ρHr values were obtained from the variable contact time and by delayed contact time experiment, because these parameter indicate the order of polysaccharides. From the values of this parameter, we found that this polysaccharide is completely non-ordered. (author)

Photochemical deposition of NiCoO x thin films from Ni/Co heteronuclear triketonate complexes

International Nuclear Information System (INIS)

Buono-Core, G.E.; Tejos, M.; Cabello, G.; Guzman, N.; Hill, R.H.

2006-01-01

UV light irradiation of thin films of a polyketonate Ni/Co heteronuclear complex, NiCo(DBA) 2 [DBA, dibenzoylacetone)], spin coated on Si(1 0 0) substrates produced NiCoO x mixed oxides as amorphous films. On annealing at 600 deg. C under air, the mixed oxide film decomposed to NiO and CoO as indicated by XRD measurements. The morphology of the as-deposited films was examined by AFM analysis showing a smooth surface with low rms roughness values. The ratio of Ni/Co (1.08) present in the film reflects the stoichiometry in the starting compound within the experimental error, as shown by XPS analysis. The large amount of carbon (20.8%) detected on the surface of the film may be due to the presence of phenyl rings in the precursor complex

Two-dimensional NMR studies of allyl palladium complexes of ...

Indian Academy of Sciences (India)

Administrator

h3-Allyl complexes are intermediates in organic synthetic reactions such as allylic alkylation and amination. There is growing interest in understanding the structures of chiral h3-allyl intermediates as this would help to unravel the mechanism of enantioselective C–C bond forming reactions. Two-dimensional NMR study is a.

Conformational, vibrational, NMR and DFT studies of N-methylacetanilide.

Science.gov (United States)

Arjunan, V; Santhanam, R; Rani, T; Rosi, H; Mohan, S

2013-03-01

A detailed conformational, vibrational, NMR and DFT studies of N-methylacetanilide have been carried out. In DFT, B3LYP method have been used with 6-31G(**), 6-311++G(**) and cc-pVTZ basis sets. The vibrational frequencies were calculated resulting in IR and Raman frequencies together with intensities and Raman depolarisation ratios. The dipole moment derivatives were computed analytically. Owing to the complexity of the molecule, the potential energy distributions of the vibrational modes of the compound are also calculated. Isoelectronic molecular electrostatic potential surface (MEP) and electron density surface were examined. (1)H and (13)C NMR isotropic chemical shifts were calculated and the assignments made are compared with the experimental values. The energies of important MO's of the compound were also determined from TD-DFT method. Copyright © 2012 Elsevier B.V. All rights reserved.

sup(1)H-NMR study of restricted rotation in dithiophosphoromethyl acetanilides

International Nuclear Information System (INIS)

Kovacs, Zs.

1985-01-01

sup(1)H-NMR spectra of a series of dithiophosphoromethyl acetanilide derivatives were investigated. The presence of an ortho substituted aryl group bonded to the nitrogen atom of the amide group allowed the observation of restricted internal rotation around the aryl-nitrogen bond. Coalescence temperature and the values of the free energy of activation were determined from the temperature dependent NMR behaviour of these molecules. The possibility of cis-trans isomerism about the nitrogen carbonyl bond was also studied, and the assignment of the conformation of the existing isomer was also made using the aromatic solvent induced shift. (author)

Mössbauer and NMR study of novel Tin(IV)-lactames

International Nuclear Information System (INIS)

Kuzmann, Erno; Szalay, Roland; Homonnay, Zoltan; Nagy, Sandor

2012-01-01

N-tributylstannylated 2-pyrrolidinone was reacted with tributyltin triflate in different molar ratios and the complex formation monitored using 1 H-NMR, 13 C-NMR and 119 Sn Mössbauer spectroscopy. Comparing the carbon NMR and tin Mössbauer results, a reaction scheme is suggested for the complexation which assumes the formation of a simultaneously O- and N-tributylstannylated pyrrolidinone cation. The formation of the only O-stannylated pyrrolidinone is also assumed to account for the non-constant Mössbauer parameters of the two tin environments in the distannylated pyrrolidinone cation when the ratio of tributyltin triflate is increased in the reaction.

NMR imaging of cerebral infarction

International Nuclear Information System (INIS)

Takusagawa, Yoshihiko; Yamaoka, Naoki; Doi, Kazuaki; Okada, Keisei

1987-01-01

One hundred and five patients with cerebral infarction were studied by nuclear magnetic resonance (NMR) CT (resistive type of magnet with strength of 0.1 tesla) and X-ray CT. Pulse sequences used saturation recovery (Tr = 600 mSec), Inversion recovery (Tr = 500 mSec, Td = 300 mSec) and spin echo (Tr = 1500 mSec, Te = 40, 80, 120, 160 mSec). Fifteen cases were examined by NMR-CT within 24 hours from onset. Proton NMR imaging could not detect cerebral ischemia as early as 2 hours after onset, but except could detect the lesions in Se image the area of cerebral infarct 3 hours after onset. After 5 hours from onset image changes in SE were evident and corresponded to the area of cerebral infarct, but image changes in IR could not fully delineate the infarcted area. NMR images of 41 year-old woman with cerebral embolism by MCA trunck occlusion associated with mitral stenosis were presented, and NMR-CT was examined 10 hours, 9th and 43th days after episode of MCA occlusion. Sixty patents (64 times) with lacunar infarction were studied by NMR-CT and X-ray CT. The inversion recovery images were used mainly for detection of lesions and comparison with X-ray CT. In 160 lesions which were detected by NMR-CT or X-ray CT, could 156 lesions be detected by NMR-CT and 78 lesions by X-ray CT. Inversion recovery images were more useful for detection of lacunes than X-ray CT. Calculated T1 and T2 values prolonged with time course from onset. (author)

Bentonite pore structure based on SAXS, chloride exclusion and NMR studies

International Nuclear Information System (INIS)

Muurinen, A.; Carlsson, T.

2013-11-01

Water-saturated bentonite is planned to be used in many countries as an important barrier component in high-level nuclear waste (HLW) repositories. Knowledge about the microstructure of the bentonite and the distribution of water between interlayer and non-interlayer pores is important for modelling of long-term processes. In this work the microstructure of water-saturated samples prepared from Na montmorillonite, Ca-montmorillonite, sodium bentonite MX-80 and calcium bentonite Deponit CaN were studied with nuclear magnetic resonance (NMR) and small-angle xray scattering spectroscopy (SAXS). The sample dry densities ranged between 0.3 and 1.6 g/cm 3 . The NMR technique was used to get information about the volumes of different water types in the bentonite samples. The results were obtained using 1H NMR spin-lattice T 1ρ relaxation time measurements using the short inter-pulse method. The interpretation of the NMR results was made by fitting distributions of exponentials to observed decay curves. The SAXS measurements were used to get information about the size distribution of the interlayer distance of montmorillonite. The chloride porosity measurements and Donnan exclusion calculations were used together with the SAXS results for evaluation of the bentonite microstructure. The NMR studies and SAXS studies coupled with Cl porosity measurements provided very similar pictures of how the porewater is divided in interlayer and non-interlayer water in MX-80 bentonite. In the case where MX-80 of a dry density 1.6 g/cm 3 was equilibrated with 0.1 M NaCl solution, the results indicated an interlayer porosity of 30 % and non-interlayer porosity of 12 %. The interlayer space mainly contained two water layers but also spaces with more water layers were present. The average size of the non-interlayer pores was evaluated to be 120 - 150 A. From the montmorillonite surface area 98 % was interlayer and 2 % non-interlayer. Evaluation of the interlayer and non

Proton NMR study of α-MnH 0.06

Science.gov (United States)

Soloninin, A. V.; Skripov, A. V.; Buzlukov, A. L.; Antonov, V. E.; Antonova, T. E.

2004-07-01

Proton nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates for the solid solution α-MnH 0.06 have been measured over the temperature range 11-297 K and the resonance frequency range 20-90 MHz. A considerable shift and broadening of the proton NMR line and a sharp peak of the spin-lattice relaxation rate are observed near 130 K. These effects are attributed to the onset of antiferromagnetic ordering below the Néel temperature TN≈130 K. The proton NMR line does not disappear in the antiferromagnetic phase; this suggests a small magnitude of the local magnetic fields at H-sites in α-MnH 0.06. The spin-lattice relaxation rate in the paramagnetic phase is dominated by the effects of spin fluctuations.

Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, 2H NMR, and 31P NMR spectroscopy

Science.gov (United States)

Pötzschner, B.; Mohamed, F.; Bächer, C.; Wagner, E.; Lichtinger, A.; Bock, D.; Kreger, K.; Schmidt, H.-W.; Rössler, E. A.

2017-04-01

We investigate the secondary (β-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of 2H and 31P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a β-relaxation (β1 (SBC) and β2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the β-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical 31P NMR echo spectra of the β2-process, very similar spectral features are observed for the (deuterated) SBC component by 2H NMR, in addition to its "own" β1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τβ2 are the same. Furthermore, T1(T) of TPP in the temperature region of the β2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the β-process introduced by one component are essentially independent of the second component. Finally, at cTPP ≤ 20% one

Probing membrane protein structure using water polarization transfer solid-state NMR.

Science.gov (United States)

Williams, Jonathan K; Hong, Mei

2014-10-01

Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected (1)H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins. Copyright © 2014 Elsevier Inc. All

Structural elucidation of the Brucella melitensis M antigen by high-resolution NMR at 500 MHz

International Nuclear Information System (INIS)

Bundle, D.R.; Cherwonogrodzky, J.W.; Perry, M.B.

1987-01-01

The Brucella M antigen from the species type strain Brucella melitensis 16M has been identified as a component of the cell wall lipopolysaccharide (LPS). O polysaccharide liberated from this LPS by mild acid hydrolysis exhibited M activity in serological tests and was shown to be a homopolymer of 4-formamido-4,6-dideoxy-α-D-mannopyranosyl residues arranged in an oligosaccharide repeating unit as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the native lipopolysaccharide. Structural analysis of the O polysaccharide by NMR methods was difficult due to apparent microheterogeneity of the repeating unit, which was in fact caused by the presence of rotational isomers of the N-formyl moiety. This problem was resolved by chemical modification of the polysaccharide to its amino and N-acetyl derivatives, the 500-MHz 1 H and 125-MHz 13 C NMR spectra of which could be analyzed in terms of a unique structure through application of pH-dependent β-shifts and two-dimensional techniques that included COSY, relayed COSY, and NOESY experiments together with heteronuclear C/H shift correlation spectroscopy. On the basis of these experiments and supported by methylation and periodate oxidation data, the structure of the M polysaccharide was determined as a linear polymer of unbranched pentasaccharide repeating units consisting of four 1,2-linked and one 1,3-lined 4,6-dideoxy-4-formamido-α-D-mannopyranosyl residues. The marked structural similarity of the M antigen and the A antigen, which is known to be a 1,2-linked homopolysaccharide of 4,6-dideoxy-4-formamido-α-D-mannopyranosyl units, accounts for cross-serological reactions of the two and the long-standing confusion surrounding the nature of their antigenic determinants

Structural characterization by NMR of the natively unfolded extracellular domain of beta-dystroglycan: toward the identification of the binding epitope for alpha-dystroglycan.

Science.gov (United States)

Bozzi, Manuela; Bianchi, Marzia; Sciandra, Francesca; Paci, Maurizio; Giardina, Bruno; Brancaccio, Andrea; Cicero, Daniel O

2003-11-25

Dystroglycan (DG) is an adhesion molecule playing a crucial role for tissue stability during both early embriogenesis and adulthood and is composed by two tightly interacting subunits: alpha-DG, membrane-associated and highly glycosylated, and the transmembrane beta-DG. Recently, by solid-phase binding assays and NMR experiments, we have shown that the C-terminal domain of alpha-DG interacts with a recombinant extracellular fragment of beta-DG (positions 654-750) independently from glycosylation and that the linear binding epitope is located between residues 550 and 565 of alpha-DG. In order to elucidate which moieties of beta-DG are specifically involved in the complex with alpha-DG, the ectodomain has been recombinantly expressed and purified in a labeled ((13)C,(15)N) form and studied by multidimensional NMR. Although it represents a natively unfolded protein domain, we obtained an almost complete backbone assignment. Chemical shift index, (1)H-(15)N heteronuclear single-quantum coherence and nuclear Overhauser effect (HSQC-NOESY) spectra and (3)J(HN,H)(alpha) coupling constant values confirm that this protein is highly disordered, but (1)H-(15)N steady-state NOE experiments indicate that the protein presents two regions of different mobility. The first one, between residues 659 and 722, is characterized by a limited degree of mobility, whereas the C-terminal portion, containing about 30 amino acids, is highly flexible. The binding of beta-DG(654-750) to the C-terminal region of the alpha subunit, alpha-DG(485-620), has been investigated, showing that the region of beta-DG(654-750) between residues 691 and 719 is involved in the interaction.

Some nitrogen-14 NMR studies in solids

International Nuclear Information System (INIS)

Pratum, T.K.

1983-11-01

The first order quadrupolar perturbation of the 14 N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long 14 N longitudinal relaxation times (T 1 ) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between 14 N and 1 H. Using quadrupolar echo and CP techniques, the 14 N quadrupolar coupling constants (e 2 qQ/h) and asymmetry parameters (eta) have been obtained for a variety of tetraalkylammonium compounds by observation of their quadrupolar powder patterns at various temperatures. For choline chloride and iodide the 14 N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects

Studies of Superfluid 3He Confined to a Regular Submicron Slab Geometry, Using SQUID NMR

International Nuclear Information System (INIS)

Casey, Andrew; Corcoles, Antonio; Lusher, Chris; Cowan, Brian; Saunders, John

2006-01-01

The effect on the superfluid ground state of confining p-wave superfluid 3He in regular geometries of characteristic size comparable to the diameter of the Cooper pair remains relatively unexplored, in part because of the demands placed by experiments on the sensitivity of the measuring technique. In this paper we report preliminary experiments aimed at the study of 3He confined to a slab geometry. The NMR response of a series of superfluid samples has been investigated using a SQUID NMR amplifier. The sensitivity of this NMR spectrometer enables samples of order 1017 spins, with low filling factor, to be studied with good resolution

13C-NMR assignment, structure, and dynamics of deoxyoligonucleotides

International Nuclear Information System (INIS)

Zanatta, N.; Borer, P.N.; Levy, G.C.

1986-01-01

The unique spectral properties of 13 C-NMR for studying nucleic acids and some of the important features of 13 C-NMR in oligonucleotide studies are demostrated. The main difficulty in studying oligonucleotides by 13 C-NMR and recent improvements in NMR instrumentation and advances in oligonucleotide synthesis are presented. The high resolution 13 C-NMR spectra, T 1 relaxation times and NOEs were measured for duplex of the self-complementary oligo-DNAs: d(CG) 3 and d(GGTATACC) are studied. The target of this study is to developed a systematic 13 C-NMR spectral assignment and to investigate the structure and dynamics of these two sequences by this techniques. (M.J.C.) [pt

NMR: its application to the experimental study of hydrocephalus and brain edema

Energy Technology Data Exchange (ETDEWEB)

Asato, R; Murata, T; Mori, K; Handa, H [Kyoto Univ. (Japan). Faculty of Medicine

1981-06-01

The pulsed NMR technique is very sensitive to molecular movement because its observation frequency is in the range of the rates of molecular movement. Furthermore it makes it possible to study the interested molecules in the biological tissues physically and noninvasively. In this report we have investigated the experimental brain edema and hydrocephalus, in both of which the tissue fluid changes are main pathology, through /sup 1/H-NMR relaxation study of water molecule in the brain tissues. The longitudinal (T/sub 1/) and the transverse (T/sub 2/) relaxation times were measured with Varian-HR-220 spectrometer modified with Nicolet-TT-100 PFT system. The experimental materials were the adult male Wister rats suffering from cold injury edema and the adult canines suffering from kaolin hydrocephalus. The study showed firstly that in brain edema no particular changes were found for relaxation times in the white matter, whereas in the gray matter, discrepancy between the changes of T/sub 1/ and T/sub 2/ was observed. That is to say, there were 2 components of T/sub 2/ in contrast with single T/sub 1/ value in the same sample of the edematous gray matter, which indicates the existence of 2 fractions of tissue water, not exchanging on an NMR time scale. Secondary, a good correlation between the longitudinal (T/sub 1/) relaxation time and the tissue water content was found for the dog brains, which suggests that we can analyse the NMR relaxation data of the dog brains based on the two-fraction fast-exchange model.

Continuous Flow 1H and 13C NMR Spectroscopy in Microfluidic Stripline NMR Chips

NARCIS (Netherlands)

Oosthoek-de Vries, Anna Jo; Bart, Jacob; Tiggelaar, Roald M.; Janssen, Johannes W.G.; van Bentum, Jan (P.J.M.); Gardeniers, Han J.G.E.; Kentgens, Arno P.M.

2017-01-01

Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline's favorable geometry. In this study we demonstrate the possibility of

NMR studies of electrophoretic mobility in surfactant systems

International Nuclear Information System (INIS)

Conveney, F.M.; Strange, J.H.; Smith, A.L.; Smith, E.G.

1989-01-01

An experimental technique is described in which the flow of electrically charged micelles is measured in the presence of an applied electric field using an NMR technique. The method is used to determine the electrophoretic mobility at ambient temperature of a 5% aqueous solution of sodium dodecyl sulphate and is shown to provide a new technique for the study of electrophoresis in surfactant solutions. (author). 8 refs.; 4 figs

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes.

Science.gov (United States)

Adam, Christian; Beele, Björn B; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J

2015-02-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15 N labeling and characterized by NMR and LIFDI-MS methods. 15 N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15 N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP) 3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP) 3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.

NMR study of local diamagnetic properties of carbon structures with multiwalled nanotubes

International Nuclear Information System (INIS)

Nikolaev, E.G.; Omel'yanovsky, O.E.; Prudkovsky, V.S.; Sadakov, A.V.; Tsebro, V.I.

2009-01-01

The reasons for the high diamagnetic susceptibility of carbon columns, which are covered with a nanotube mesh, from the interior part of cathode deposits have been studied by means of NMR. A comparative study is made of the 13 C NMR spectra and the magnetic susceptibility of carbon columns before and after ultrasonic processing as well as of finely dispersed material, obtained as a result of such processing, enriched with multilayer nanotubes. The strong diamagnetism of the carbon columns is apparently associated with a quite dense conglomerate of graphite particles, nanotubes, and multilayer polyhedral particles present in their core and not with the surface mesh of multilayer nanotubes. To make a more accurate determination of the character of the anisotropy of the magnetic susceptibility of multilayer carbon nanotubes, the form of the 13 C NMR spectra of samples enriched with multilayer nanotubes, where the nanotubes are either not oriented or only partially oriented, is analyzed. It is shown that the diamagnetic susceptibility of multilayer carbon nanotubes is highest when the magnetic field is oriented perpendicular to their axis

Solution structure and DNA-binding properties of the C-terminal domain of UvrC from E.coli

NARCIS (Netherlands)

Singh, S.; Folkers, G.E.; Bonvin, A.M.J.J.; Boelens, R.; Wechselberger, R.W.; Niztayev, A.; Kaptein, R.

2002-01-01

The C-terminal domain of the UvrC protein (UvrC CTD) is essential for 5' incision in the prokaryotic nucleotide excision repair process. We have determined the three-dimensional structure of the UvrC CTD using heteronuclear NMR techniques. The structure shows two helix±hairpin±helix (HhH) motifs

Ligand-receptor Interactions by NMR Spectroscopy

Directory of Open Access Journals (Sweden)

Novak. P.

2008-04-01

Full Text Available Today NMR spectroscopy is a method of choice for elucidation of interactions between biomolecules and the potential ligands. Knowledge on these interactions is an essential prerequisite for the rational drug design. The most important contribution of NMR to drug design a few years ago was the 3D structure determination of proteins. Besides delivering the 3D structures of the free proteins as a raw material for the modeling studies on ligand binding, NMR can directly yield valuable experimental data on the biologically important protein-ligand complexes. In addition to X-ray diffraction, NMR spectroscopy can provide information on the internal protein dynamics ordynamics of intermolecular interactions. Changes in NMR parameters allow us to detect ("SAR by NMR" and quantitatively determine binding affinities (titration, diffusion NMR experiments, etc. of potential ligands. Also, it is possible to determine the binding site and conformations of ligands, receptors and receptor-ligand complexes with the help of NMR methods such as tr-NOESY. Epitopes or functional groups responsible for binding of ligands to the receptor can be identified by employing STD or WaterLOGSY experiments. In this review are described some of the most frequent NMR methods for the characterization of the interactions between biomolecules and ligands, together with their advantages and disadvantages.

Lateral interactions in the photoreceptor membrane: a NMR study

International Nuclear Information System (INIS)

Mollevanger, L.C.P.J.

1987-01-01

The photoreceptor membrane has an exceptionally high content of polyunsaturated fatty acyl chains combined with a high amount of phosphatidyl ethanolamine. It is situated in a cell organelle, the rod outer segment, with a high biological activity in which controlable trans-membrane currents of different ions play an important role. These characteristics make it a very interesting biological membrane to search for the existence of non-bilayer structures. Therefore in this thesis a detailed study of the polymorphic phase behaviour of the rod outer segment photoreceptor lipids was undertaken, concerning modulation of the polymorphic phase behaviour of photoreceptor membrane lipids by divalent cations and temperature, polymorphism of the individual phospholipid classes phosphatidylethanolamine and phosphatidylserine and effects of cholesterol, bilayer stabilization by (rhod)opsin. Morphologically intact rod outer segment possesses a large magnetic anisotropy. This property is used to obtain 31 P-NMR of oriented photoreceptor membranes which allows spectral analysis and identification of individual phospholipid classes, and allows to study lateral lipid diffusion in intact disk membranes. The power of high resolution solid state 13 C-NMR to study the conformation of the chromophore in rhodopsin is demonstrated. (Auth.)

NMR characterization of hydrocarbon adsorption on calcite surfaces: A first principles study

Energy Technology Data Exchange (ETDEWEB)

Bevilaqua, Rochele C. A.; Miranda, Caetano R. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Rigo, Vagner A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Universidade Tecnológica Federal do Paraná, UTFPR, Cornélio Procópio, PR (Brazil); Veríssimo-Alves, Marcos [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Departamento de Física, ICEx, Universidade Federal Fluminense, UFF, Volta Redonda, RJ (Brazil)

2014-11-28

The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca{sup 2+}. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO{sub 3} (101{sup ¯}4)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for {sup 43}Ca, {sup 13}C, and {sup 17}O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.

NMR spectroscopy and drug development

International Nuclear Information System (INIS)

Craik, D.; Munro, S.

1990-01-01

The use of nuclear magnetic resonance (NMR) spectroscopy for structural and conformational studies on drug molecules, the three-dimensional investigation of proteins structure and their interactions with ligands are discussed. In-vivo NMR studies of the effects of drugs on metabolism in perfused organs and whole animals are also briefly presented. 5 refs., ills

Part I. Generation of tailored radio-frequency pulses for NMR. Part II. Deuterium NMR studies of oriented DNA, and its interaction with water

International Nuclear Information System (INIS)

Brandes, R.

1988-01-01

A novel method for generating tailored radio-frequency pulses for use in NMR is presented. For this purpose, an inexpensive device based on analog audio filters was built. As an application, the superior selectivity of this method is shown by comparing it with a soft pulse excitation. The theoretical response of the magnetization to these tailored rf pulses is also calculated. Deuterium NMR line shapes of 2 H-labeled purine bases in solid, uniaxially oriented Li- and Na-DNA have been obtained. The spectral densities of motion were determined for the Li-DNA samples to test a model for uncorrelated, restricted base motion. For the first time, a 2 H spectrum is reported for 2 H labeled DNA in the liquid crystalline state. A procedure is outlined to separate the base motion from the DNA axis motion. In addition to the studies of DNA itself, the interaction of water (D 2 O) with samples of uniaxially oriented Na- and Li-DNA have been studied by high resolution 2 H NMR

Comparative NMR study of nPrBTP and iPrBTP

Energy Technology Data Exchange (ETDEWEB)

Adam, C.; Muellich, U.; Geist, A.; Geckeis, H. [Karlsruhe Institute of Technology - KIT, Institute for Nuclear Waste Disposal - INE, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rohde, V. [Fraunhofer Institute for Chemical Technology - ICT, Environmental Engineering, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany); Kaden, P. [Helmholtz-Zentrum Dresden - Rossendorf e. V., Institute of Resource Ecology, Bautzner Landstrasse 400, 01328 Dresden (Germany); Panak, P.J. [Karlsruhe Institute of Technology - KIT, Institute for Nuclear Waste Disposal - INE, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); University of Heidelberg, Department of Physical Chemistry, Im Neuenheimer Feld 253, 69120 Heidelberg (Germany)

2016-07-01

Bis-triazinyl-pyridine type ligands are important extracting agents for separating trivalent actinide ions from trivalent lanthanides. The alkyl substituents on the lateral triazine rings have a significant effect on the stability of the ligand against hydrolysis and radiolysis. Furthermore they influence solubility, extraction behaviour and selectivity. TRLFS and extraction studies suggest differences in complexation and extraction behaviour of BTP ligands bearing iso-propyl or n-propyl substituents, respectively. As NMR studies allow insight into the metal-ligand bonding, we conducted NMR studies on a range of {sup 15}N-labelled nPrBTP and iPrBTP Ln(III) and Am(III) complexes. Our results show that no strong change in the metal-ligand bonding occurs, thus excluding electronic reasons for differences in complexation behaviour, extraction kinetics and selectivity. This supports mechanistic reasons for the observed differences. (authors)

Nitrogen Use Efficiency and Carbon Isotope Discrimination Study on NMR151 and NMR152 Mutant Lines Rice at Field Under Different Nitrogen Rates and Water Potentials

International Nuclear Information System (INIS)

Ahmad Nazrul Abdul Wahid; Shyful Azizi Abdul Rahman; Abdul Rahim Harun; Latiffah Nordin; Abdul Razak Ruslan; Hazlina Abdullah; Khairuddin Abdul Rahim

2016-01-01

This study was conducted to evaluate the nitrogen use efficiency and "1"3C isotope discrimination of rice mutant lines viz. NMR151 and NMR152. Both cultivars are developed under rice radiation mutagenesis programme for adaptability to aerobic conditions. In the present study, NMR151 and NMR152 were grown under conditions of varying water potentials and nitrogen levels in a field. Two water potentials and three nitrogen rates in a completely randomized design with three replications were carried out. The rice mutants were grown for 110 days under two water potentials, (i) Field capacity from 0 to 110 DAS [FC], and (ii) Field capacity from 0 to 40 DAS and 30 % dry of field capacity from 41 to 110 DAS [SS] and three nitrogen rates, (i) 0 kg N/ ha (0N), (ii) 60 kg N/ ha (60N), and (iii) 120 kg N/ ha (120N). "1"5N isotopic tracer technique was used in this study, whereby the "1"5N labeled urea fertilizer 5.20 % atom excess (a.e) was utilized as a tracer for nitrogen use efficiency (NUE) study. "1"5N isotope presence in the samples was determined using emission spectrometry and percentage of total nitrogen was determined by the Kjeldahl method. "1"5N a.e values of the samples were used in the determination of the NUE. The value of "1"3C isotope discrimination (Δ"1"3C) in the sample was determined using isotope ratio mass spectrometry (IRMS). The "1"3C isotope discrimination technique was used as a tool to identify drought resistance rice cultivars with improves water use efficiency. The growth and agronomy data, viz. plant height, number of tillers, grain yield, straw yield, and 1000 grain weight also were recorded. Results from this study showed nitrogen rates imparted significant effects on yield (grain and straw) plant height, number of tillers and 1000 grain weight. Water potentials had significant effects only on 1000 grain weight and Δ"1"3C. The NUE for both mutant lines rice showed no significant different between treatments. Both Rice mutant lines rice NMR151

Some nitrogen-14 NMR studies in solids

Energy Technology Data Exchange (ETDEWEB)

Pratum, T.K.

1983-11-01

The first order quadrupolar perturbation of the /sup 14/N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long /sup 14/N longitudinal relaxation times (T/sub 1/) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between /sup 14/N and /sup 1/H. Using quadrupolar echo and CP techniques, the /sup 14/N quadrupolar coupling constants (e/sup 2/qQ/h) and asymmetry parameters (eta) have been obtained for a variety of tetraalkylammonium compounds by observation of their quadrupolar powder patterns at various temperatures. For choline chloride and iodide the /sup 14/N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects.

β-NMR sample optimization

CERN Document Server

Zakoucka, Eva

2013-01-01

During my summer student programme I was working on sample optimization for a new β-NMR project at the ISOLDE facility. The β-NMR technique is well-established in solid-state physics and just recently it is being introduced for applications in biochemistry and life sciences. The β-NMR collaboration will be applying for beam time to the INTC committee in September for three nuclei: Cu, Zn and Mg. Sample optimization for Mg was already performed last year during the summer student programme. Therefore sample optimization for Cu and Zn had to be completed as well for the project proposal. My part in the project was to perform thorough literature research on techniques studying Cu and Zn complexes in native conditions, search for relevant binding candidates for Cu and Zn applicable for ß-NMR and eventually evaluate selected binding candidates using UV-VIS spectrometry.

NMR imaging

International Nuclear Information System (INIS)

Andrew, E.R.

1983-01-01

Since hydrogen is the most abundant element in all living organisms, proton NMR lends itself well as a method of investigation in biology and medicine. NMR imaging has some special advantages as a diagnostic tool: no ionizing radiation is used, it is noninvasive; it provides a safer means of imaging than the use of x-rays, gamma rays, positrons, or heavy ions. In contrast with ultrasound, the radiation penetrates the bony structures without attenuation. In additional to morphological information, NMR imaging provides additional diagnostic insights through relaxation parameters, which are not available from other imaging methods. In the decade since the first primitive NMR images were obtained, the quality of images now obtained approaches those from CT x-ray scanners. Prototype instruments are being constructed for clinical evaluation and the first whole-body scanners are beginning to appear on the market at costs comparable to CT scanners. Primary differences in equipment for conventional NMR and NMR imaging are the much larger aperture magnets that are required for the examination of human subjects and the addition of coils to generate field gradients and facilities for manipulating the gradients. Early results from clinical trials in many parts of the world are encouraging, and in a few years, the usefuleness of this modality of medical imaging to the medical profession in diagnosis and treatment of disease will be defined. 10 figures

Fundamentals of Protein NMR Spectroscopy

CERN Document Server

Rule, Gordon S

2006-01-01

NMR spectroscopy has proven to be a powerful technique to study the structure and dynamics of biological macromolecules. Fundamentals of Protein NMR Spectroscopy is a comprehensive textbook that guides the reader from a basic understanding of the phenomenological properties of magnetic resonance to the application and interpretation of modern multi-dimensional NMR experiments on 15N/13C-labeled proteins. Beginning with elementary quantum mechanics, a set of practical rules is presented and used to describe many commonly employed multi-dimensional, multi-nuclear NMR pulse sequences. A modular analysis of NMR pulse sequence building blocks also provides a basis for understanding and developing novel pulse programs. This text not only covers topics from chemical shift assignment to protein structure refinement, as well as the analysis of protein dynamics and chemical kinetics, but also provides a practical guide to many aspects of modern spectrometer hardware, sample preparation, experimental set-up, and data pr...

Oriented solid-state NMR spectrosocpy

DEFF Research Database (Denmark)

Bertelsen, Kresten

This thesis is concerned with driving forward oriented solid-state NMR spectroscopy as a viable technique for studying peptides in membrane bilayers. I will show that structural heterogeneity is an intrinsic part of the peptide/lipid system and that NMR can be used to characterize static...... and dynamic structural features of the peptides and its local surroundings. In fact one need to take into account the dynamical features of the system in order to correctly predict the structure from oriented solid-state NMR spectra.      ...

NMR-CT scanner

International Nuclear Information System (INIS)

Kose, Katsumi; Sato, Kozo; Sugimoto, Hiroshi; Sato, Masataka.

1983-01-01

A brief explanation is made on the imaging methods for a practical diagnostic NMR-CT scanner : A whole-body NMR-CT scanner utilizing a resistive magnet has been developed by Toshiba in cooperation with the Institute for Solid State Physics, the University of Tokyo. Typical NMR-CT images of volunteers and patients obtained in the clinical experiments using this device are presented. Detailed specifications are also shown about the practical NMR-CTs which are to be put on the market after obtaining the government approval. (author)

Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes

Directory of Open Access Journals (Sweden)

Jean-Christophe Daigle

2018-01-01

Full Text Available We report the analysis of comb-like polymers by solid-state NMR. The polymers were previously evaluated as solid-polymer-electrolytes (SPE for lithium-polymer-metal batteries that have suitable ionic conductivity at 60 °C. We propose to develop a correlation between 13C solid-state NMR measurements and phase segregation. 13C solid-state NMR is a perfect tool for differentiating polymer phases with fast or slow motions. 7Li was used to monitor the motion of lithium ions in the polymer, and activation energies were calculated.

Purification and Characterization of Recombinant N-Terminally Pyroglutamate-Modified Amyloid-β Variants and Structural Analysis by Solution NMR Spectroscopy.

Directory of Open Access Journals (Sweden)

Christina Dammers

Full Text Available Alzheimer's disease (AD is the leading cause of dementia in the elderly and is characterized by memory loss and cognitive decline. Pathological hallmark of AD brains are intracellular neurofibrillary tangles and extracellular amyloid plaques. The major component of these plaques is the highly heterogeneous amyloid-β (Aβ peptide, varying in length and modification. In recent years pyroglutamate-modified amyloid-β (pEAβ peptides have increasingly moved into the focus since they have been described to be the predominant species of all N-terminally truncated Aβ. Compared to unmodified Aβ, pEAβ is known to show increased hydrophobicity, higher toxicity, faster aggregation and β-sheet stabilization and is more resistant to degradation. Nuclear magnetic resonance (NMR spectroscopy is a particularly powerful method to investigate the conformations of pEAβ isoforms in solution and to study peptide/ligand interactions for drug development. However, biophysical characterization of pEAβ and comparison to its non-modified variant has so far been seriously hampered by the lack of highly pure recombinant and isotope-enriched protein. Here we present, to our knowledge, for the first time a reproducible protocol for the production of pEAβ from a recombinant precursor expressed in E. coli in natural isotope abundance as well as in uniformly [U-15N]- or [U-13C, 15N]-labeled form, with yields of up to 15 mg/l E. coli culture broth. The chemical state of the purified protein was evaluated by RP-HPLC and formation of pyroglutamate was verified by mass spectroscopy. The recombinant pyroglutamate-modified Aβ peptides showed characteristic sigmoidal aggregation kinetics as monitored by thioflavin-T assays. The quality and quantity of produced pEAβ40 and pEAβ42 allowed us to perform heteronuclear multidimensional NMR spectroscopy in solution and to sequence-specifically assign the backbone resonances under near-physiological conditions. Our results suggest

Changes in Lignin and Polysaccharide Components in 13 Cultivars of Rice Straw following Dilute Acid Pretreatment as Studied by Solution-State 2D 1H-13C NMR

Science.gov (United States)

Teramura, Hiroshi; Sasaki, Kengo; Oshima, Tomoko; Aikawa, Shimpei; Matsuda, Fumio; Okamoto, Mami; Shirai, Tomokazu; Kawaguchi, Hideo; Ogino, Chiaki; Yamasaki, Masanori; Kikuchi, Jun; Kondo, Akihiko

2015-01-01

A renewable raw material, rice straw is pretreated for biorefinery usage. Solution-state two-dimensional (2D) 1H-13 C hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, was used to analyze 13 cultivars of rice straw before and after dilute acid pretreatment, to characterize general changes in the lignin and polysaccharide components. Intensities of most (15 of 16) peaks related to lignin aromatic regions, such as p-coumarate, guaiacyl, syringyl, p-hydroxyphenyl, and cinnamyl alcohol, and methoxyl, increased or remained unchanged after pretreatment. In contrast, intensities of most (11 of 13) peaks related to lignin aliphatic linkages or ferulate decreased. Decreased heterogeneity in the intensities of three peaks related to cellulose components in acid-insoluble residues resulted in similar glucose yield (0.45–0.59 g/g-dry biomass). Starch-derived components showed positive correlations (r = 0.71 to 0.96) with glucose, 5-hydroxymethylfurfural (5-HMF), and formate concentrations in the liquid hydrolysates, and negative correlations (r = –0.95 to –0.97) with xylose concentration and acid-insoluble residue yield. These results showed the fate of lignin and polysaccharide components by pretreatment, suggesting that lignin aromatic regions and cellulose components were retained in the acid insoluble residues and starch-derived components were transformed into glucose, 5-HMF, and formate in the liquid hydrolysate. PMID:26083431

Sesquiterpenes from the Saudi Red Sea: Litophyton arboreum with their cytotoxic and antimicrobial activities.

Science.gov (United States)

Abou El-Kassem, Lamia T; Hawas, Usama W; El-Desouky, Samy K; Al-Farawati, Radwan

2018-01-26

A new pseudoguaiane-type sesquiterpene named litopharbol (1) was isolated from the methanolic extract of the Red Sea soft coral Litophyton arboreum, along with known sesquiterpenoids alismol (2), alismorientol B (3), teuhetenone A (4), and calamusin I (5); steroid, 24-methyl-cholesta-5,24(28)-diene-3β-ol (6), alkyl glyceryl ether, chimyl alcohol (7); sphingolipid, erythro-N-dodecanoyl-docosasphinga-(4E,8E)-dienine (8); and nitrogenous bases, thymine (9) and thymidine (10). The structures were determined on the basis of nuclear magnetic resonance (NMR) spectroscopic (1D and 2D NMR data including heteronuclear single quantum coherence spectroscopy, heteronuclear multiple-bond correlation spectroscopy, and nuclear Overhauser effect spectroscopy) and mass spectrometric analyses. Compounds 1-5 were explored for antimicrobial activity and cancer cell line sensitivity tests. Compound 1 exhibited antibacterial activity against Bacillus cereus with a minimum inhibition concentration of 1.8 μg/mL, whereas compound 3 showed significant potent cytotoxic effect against MCF-7 (breast cancer cells) with IC50 4.32 μM.

NMR studies of defects created by irradiation in metals

International Nuclear Information System (INIS)

Minier, M.; Minier, C.

1983-06-01

Nuclear Magnetic Resonance has been rarely used to study point defects created by irradiation in metals. Information obtained in this field using N.M.R. are shown. Some results are also described: characterization of migrating defects in electron irradiated copper; mobility of the complex interstitial-impurity in Al with 150 ppm of chromium; interstitial structure in irradiated aluminum and autodiffusion in metals [fr

Solution NMR Spectroscopy in Target-Based Drug Discovery.

Science.gov (United States)

Li, Yan; Kang, Congbao

2017-08-23

Solution NMR spectroscopy is a powerful tool to study protein structures and dynamics under physiological conditions. This technique is particularly useful in target-based drug discovery projects as it provides protein-ligand binding information in solution. Accumulated studies have shown that NMR will play more and more important roles in multiple steps of the drug discovery process. In a fragment-based drug discovery process, ligand-observed and protein-observed NMR spectroscopy can be applied to screen fragments with low binding affinities. The screened fragments can be further optimized into drug-like molecules. In combination with other biophysical techniques, NMR will guide structure-based drug discovery. In this review, we describe the possible roles of NMR spectroscopy in drug discovery. We also illustrate the challenges encountered in the drug discovery process. We include several examples demonstrating the roles of NMR in target-based drug discoveries such as hit identification, ranking ligand binding affinities, and mapping the ligand binding site. We also speculate the possible roles of NMR in target engagement based on recent processes in in-cell NMR spectroscopy.

A New Benzoyl Compound Isolated from the Endophytic Fungi of Kandis Gajah (Garcinia griffithii and Asam Kandis (Garcinia cowa

Directory of Open Access Journals (Sweden)

Elfita Elfita

2016-12-01

Full Text Available Garcinia griffithii and Garcinia cowa belong to the genus Garcinia. The genus Garcinia has been known to be a rich source of secondary metabolites, such as xanthones, benzophenones, flavonoids, steroids, terpenoids, and other phenolic derivatives. Previous investigations of endophytic fungi from G. griffithii revealed the presence of three compounds not found in the host. In order to the continue the phytochemical work on endophytic fungi of G. griffithii, the constituent of the endophytic fungi of G. griffithii was re-examined. In this study, a benzoyl compound similar to that found in the endophytic fungus of G. cowa was observed. The same benzoyl compound was also isolated from the endophytic fungus Acremonium sp of G. griffithii and Aspergillus sp of G. cowa with cultivation of eight weeks in static conditions at room temperature. The culture medium was partitioned using ethyl acetate and evaporated to obtain the concentrated extract. Isolation of compounds was performed using the chromatography method. The chemical structure was proposed on the basis of spectroscopic data, including ultraviolet (UV, infrared (IR, mass spectrometry (MS, proton nuclear magnetic resonance (1H-NMR, carbon nuclear magnetic resonance (13C-NMR, heteronuclear single-quantum correlation spectroscopy (HSQC, heteronuclear multiple-bond correlation spectroscopy (HMBC, and correlation spectroscopy (COSY.

Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

International Nuclear Information System (INIS)

Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G.; Boffo, Elisangela F.; Figueira, Glyn M.

2012-01-01

The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, 1 H HR-MAS NMR and 1 H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

Annual reports on NMR spectroscopy

CERN Document Server

Webb, Graham A; McCarthy, M J

1995-01-01

Over recent years, no other technique has grown to such importance as that of NMR spectroscopy. It is used in all branches of science where precise structural determination is required and where the nature of interactions and reactions in solution is being studied. Annual Reports on NMR Spectroscopy has established itself as a means for the specialist and non-specialist alike to become familiar with new applications of the technique in all branches of chemistry, including biochemistry, and pharmaceutics. This volume focuses on theoretical aspects of NMR nuclear shielding and on applications of

NMR spectroscopy study of agar-based polymers electrolytes

Energy Technology Data Exchange (ETDEWEB)

Mattos, R.I.; Tambelli, C.E. [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Fac. de Zootecnia e Engenharia de Alimentos; Raphael, E. [Universidade Federal de Sao Joao del-Rey (UFSJ), MG (Brazil). Dept. de Ciencias Naturais; Silva, I.D.A.; Magon, C.J.; Donoso, J.P. [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica

2012-07-01

Full text: This communication presents the results of preparation and characterization of transparent films obtained from agar and acetic acid. The films were characterized by electrochemical impedance spectroscopy (EIS) and nuclear magnetic resonance (NMR). The film formed by agar (Sigma Aldrich) was dispersed in water and kept under stirring and heating at 100 deg C. Next, glycerol, formaldehyde and different quantities of acetic acid (25 and 50 wt%) were added to this solution. The obtained solution was placed on a glass plate and left to dry for 48 hours in oven at 50 deg C to obtain the films, which were kept under vacuum before characterization. The ionic conductivity of the films display an Arrhenius behavior with activation energy E{sub a} = 78 (25 wt% of acetic acid) and E{sub a} = 87 kJ/mol (50 wt% of acetic acid). The conductivity values were 3:0 X 10{sup -6} and 1:2 X 10{sup -4} S/cm at room temperature and 4:4 X 10{sup -4} and 1:5 X 10{sup -3}S/cm at 70 deg C, for the 25 and 50 wt% of acetic acid respectively. To investigate the mechanism of protonic conduction in the polymer proton conductor proton NMR measurements were performed in the temperature range 200-370 K. The {sup 1}H-NMR results exhibit the qualitative feature associated with the proton mobility, namely the presence of well defined {sup 1}H spin-lattice relaxation maxima at 300 K. Activation energy of the order of 40 kJ/mol was obtained from the {sup 1}H-NMR line narrowing data. The ionic conductivity of the film combined with their transparency, flexibility, homogeneity and good adhesion to the glasses or metals indicate that agar-based SPEs are promising materials for used on optoelectronic applications. (author)

Medical applications of NMR imaging and NMR spectroscopy with stable isotopes. Summary

International Nuclear Information System (INIS)

Matwiyoff, N.A.

1983-01-01

The current status of NMR imaging and NMR spectroscopy are summarized. For the most part examples from the March 1983 Puerto Rico symposium are used to illustrate the utility of NMR in medicine. 18 refs., 5 figs

Medical applications of NMR imaging and NMR spectroscopy with stable isotopes. Summary

Energy Technology Data Exchange (ETDEWEB)

Matwiyoff, N.A.

1983-01-01

The current status of NMR imaging and NMR spectroscopy are summarized. For the most part examples from the March 1983 Puerto Rico symposium are used to illustrate the utility of NMR in medicine. 18 refs., 5 figs.

Studying the molecular determinants of potassium channel structure and function in membranes by solid-state NMR

NARCIS (Netherlands)

van der Cruijsen, Elwin

2014-01-01

Solid-state Nuclear Magnetic Resonance (ssNMR) has made remarkable progress in the structural characterization of membrane proteins systems at atomic resolution. Such studies can be further aided by the use of molecular dynamic simulations. Moreover, ssNMR data can be directly compared to functional

Recombinant proteins incorporating short non-native extensions may display increased aggregation propensity as detected by high resolution NMR spectroscopy

International Nuclear Information System (INIS)

Zanzoni, Serena; D’Onofrio, Mariapina; Molinari, Henriette; Assfalg, Michael

2012-01-01

Highlights: ► Bile acid binding proteins from different constructs retain structural integrity. ► NMR 15 N-T 1 relaxation data of BABPs show differences if LVPR extension is present. ► Deviations from a 15 N-T 1 /molecular-weight calibration curve indicate aggregation. -- Abstract: The use of a recombinant protein to investigate the function of the native molecule requires that the former be obtained with the same amino acid sequence as the template. However, in many cases few additional residues are artificially introduced for cloning or purification purposes, possibly resulting in altered physico-chemical properties that may escape routine characterization. For example, increased aggregation propensity without visible protein precipitation is hardly detected by most analytical techniques but its investigation may be of great importance for optimizing the yield of recombinant protein production in biotechnological and structural biology applications. In this work we show that bile acid binding proteins incorporating the common C-terminal LeuValProArg extension display different hydrodynamic properties from those of the corresponding molecules without such additional amino acids. The proteins were produced enriched in nitrogen-15 for analysis via heteronuclear NMR spectroscopy. Residue-specific spin relaxation rates were measured and related to rotational tumbling time and molecular size. While the native-like recombinant proteins show spin-relaxation rates in agreement with those expected for monomeric globular proteins of their mass, our data indicate the presence of larger adducts for samples of proteins with very short amino acid extensions. The used approach is proposed as a further screening method for the quality assessment of biotechnological protein products.

Recombinant proteins incorporating short non-native extensions may display increased aggregation propensity as detected by high resolution NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zanzoni, Serena; D' Onofrio, Mariapina; Molinari, Henriette [Department of Biotechnology, University of Verona, 37134 Verona (Italy); Assfalg, Michael, E-mail: michael.assfalg@univr.it [Department of Biotechnology, University of Verona, 37134 Verona (Italy)

2012-10-26

Highlights: Black-Right-Pointing-Pointer Bile acid binding proteins from different constructs retain structural integrity. Black-Right-Pointing-Pointer NMR {sup 15}N-T{sub 1} relaxation data of BABPs show differences if LVPR extension is present. Black-Right-Pointing-Pointer Deviations from a {sup 15}N-T{sub 1}/molecular-weight calibration curve indicate aggregation. -- Abstract: The use of a recombinant protein to investigate the function of the native molecule requires that the former be obtained with the same amino acid sequence as the template. However, in many cases few additional residues are artificially introduced for cloning or purification purposes, possibly resulting in altered physico-chemical properties that may escape routine characterization. For example, increased aggregation propensity without visible protein precipitation is hardly detected by most analytical techniques but its investigation may be of great importance for optimizing the yield of recombinant protein production in biotechnological and structural biology applications. In this work we show that bile acid binding proteins incorporating the common C-terminal LeuValProArg extension display different hydrodynamic properties from those of the corresponding molecules without such additional amino acids. The proteins were produced enriched in nitrogen-15 for analysis via heteronuclear NMR spectroscopy. Residue-specific spin relaxation rates were measured and related to rotational tumbling time and molecular size. While the native-like recombinant proteins show spin-relaxation rates in agreement with those expected for monomeric globular proteins of their mass, our data indicate the presence of larger adducts for samples of proteins with very short amino acid extensions. The used approach is proposed as a further screening method for the quality assessment of biotechnological protein products.

KUJIRA, a package of integrated modules for systematic and interactive analysis of NMR data directed to high-throughput NMR structure studies

International Nuclear Information System (INIS)

Kobayashi, Naohiro; Iwahara, Junji; Koshiba, Seizo; Tomizawa, Tadashi; Tochio, Naoya; Guentert, Peter; Kigawa, Takanori; Yokoyama, Shigeyuki

2007-01-01

The recent expansion of structural genomics has increased the demands for quick and accurate protein structure determination by NMR spectroscopy. The conventional strategy without an automated protocol can no longer satisfy the needs of high-throughput application to a large number of proteins, with each data set including many NMR spectra, chemical shifts, NOE assignments, and calculated structures. We have developed the new software KUJIRA, a package of integrated modules for the systematic and interactive analysis of NMR data, which is designed to reduce the tediousness of organizing and manipulating a large number of NMR data sets. In combination with CYANA, the program for automated NOE assignment and structure determination, we have established a robust and highly optimized strategy for comprehensive protein structure analysis. An application of KUJIRA in accordance with our new strategy was carried out by a non-expert in NMR structure analysis, demonstrating that the accurate assignment of the chemical shifts and a high-quality structure of a small protein can be completed in a few weeks. The high completeness of the chemical shift assignment and the NOE assignment achieved by the systematic analysis using KUJIRA and CYANA led, in practice, to increased reliability of the determined structure

NMR studies of interfaces, strain and anisotropy in Co/Cu multilayers

International Nuclear Information System (INIS)

Thomson, T.; Riedi, P.C.

1999-01-01

59 Co NMR studies of multilayers are able to give three direct pieces of information: (i) the crystal phase of Co, fcc (217.4 MHz), hcp (220-228 MHz) and in exotic cases bcc (198 MHz) for films measured at T= 4.2 K, (ii) the nature of the interfaces from low frequency satellite lines, and (iii) the strain state deduced from small changes in the line positions. Extensive studies of Co/Cu multilayer interfacial structures as a function of deposition technique, layer thickness, substrate/buffer layer structure and annealing temperature have been undertaken. This work has shed new light on the relationship between interfacial structure and magnetoresistance and in particular has demonstrated that flat, atomic scale, interfaces lead to greater magnetoresistance. The difference between the Co and Cu lattice constant results in an extensive, tensile in-plane strain developing in Co layers provided that some epitaxial registry is present. Information on strain effects can be obtained from the position and width of the NMR lines. The magnetic anisotropy field can be determined by measuring the field dependence of the enhancement effect due to electronic magnetisation. This provides unique insight into the distribution of magnetic anisotropy within the Co layers, as the enhancement can be investigated independently for each NMR line and, hence, provides environment specific information on magnetic anisotropy at the interfaces and in the interior of the layers

Push-through Direction Injectin NMR Automation

Science.gov (United States)

Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin.

Science.gov (United States)

Wałęsa, Roksana; Ptak, Tomasz; Siodłak, Dawid; Kupka, Teobald; Broda, Małgorzata A

2014-06-01

The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by (1)H and (13)C NMR. Six complexes EYL-Ac-Phe-NHMe, stabilized by N-H···O or/and C-H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar 'head' of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in phosphate group that acts as proton acceptor. Copyright © 2014 John Wiley & Sons, Ltd.

1H Nuclear Magnetic Resonance (NMR) metabonomic study of breast cancer in Indian population

International Nuclear Information System (INIS)

Sonkar, Kanchan; Sinha, Neeraj; Arshad, Farah

2012-01-01

Breast cancer is the most common cancer diagnosed in women worldwide with over 1.3 million new cases per year. Recently it has been observed that breast cancer is increasing very rapidly in low income countries including India. Lipids not only play very important and vital role of prime structural component in human body they are also important functional components in cellular metabolism. Transformation from benign to malignant tissue involves several biochemical processes and understanding these processes provides very useful insight related to cancer prognosis. Thus study of lipids becomes very important and NMR spectroscopy is one of the techniques which can be utilized to identifying all lipid components simultaneously. The tissue specimens (35, benign 20 and malignant 15; patient age group 47 yrs) were collected after breast surgeries and were snap frozen in liquid nitrogen. Part of all tissues was sent for routine histopathology. Lipid extraction was performed by Folch method (Folch, 1957) using cholesterol and methanol (2:1 ratio). The NMR spectra of the extracted lipids were recorded immediately after the sample preparation. All NMR experiments were performed on a Bruker Avance 800 MHz spectrometer. 1 H NMR analysis of lipid extract of breast tissue in Indian population shows there is significant elevation of phosphotidycholine, plasmalogen and esterified cholesterol with decrease in triacylglycerol in cancer breast compared to benign tissue implying that their metabolism is definitely altered during carcinogenesis. This study analyzes the role of NMR as an additional diagnostic tool on the basis of examination of lipid extract. (author)

High resolution NMR theory and chemical applications

CERN Document Server

Becker, Edwin D

1999-01-01

High Resolution NMR provides a broad treatment of the principles and theory of nuclear magnetic resonance (NMR) as it is used in the chemical sciences. It is written at an "intermediate" level, with mathematics used to augment, rather than replace, clear verbal descriptions of the phenomena. The book is intended to allow a graduate student, advanced undergraduate, or researcher to understand NMR at a fundamental level, and to see illustrations of the applications of NMR to the determination of the structure of small organic molecules and macromolecules, including proteins. Emphasis is on the study of NMR in liquids, but the treatment also includes high resolution NMR in the solid state and the principles of NMR imaging and localized spectroscopy. Careful attention is given to developing and interrelating four approaches - steady state energy levels, the rotating vector picture, the density matrix, and the product operator formalism. The presentation is based on the assumption that the reader has an acquaintan...

Investigating sorption on iron-oxyhydroxide soil minerals by solid-state NMR spectroscopy: a 6Li MAS NMR study of adsorption and absorption on goethite

DEFF Research Database (Denmark)

Nielsen, Ulla Gro; Paik, Younkee; Julmis, Keinia

2005-01-01

High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, th...... on the goethite surface. Even larger Li hyperfine shifts (289 ppm) were observed for Li+-exchanged goethite, which contains lithium ions in the tunnels of the goethite structure, confirming the Li assignment of the 145 ppm Li resonance to the surface sites. Udgivelsesdato: 2005-Oct-6...

Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

Energy Technology Data Exchange (ETDEWEB)

Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

2012-07-01

The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

Authenticity study of Phyllanthus species by NMR and FT-IR Techniques coupled with chemometric methods

Directory of Open Access Journals (Sweden)

Maiara S. Santos

2012-01-01

Full Text Available The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as "quebra-pedras" in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques.

Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

Energy Technology Data Exchange (ETDEWEB)

Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

2012-07-01

The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

{sup 11}B-NMR spectroscopic study on the interaction of epinephrine and p-BPA

Energy Technology Data Exchange (ETDEWEB)

Ichihara, K.; Yoshino, K. [Shinshu Univ., Department of Chemistry, Matsumoto, Nagano (Japan)

2000-10-01

It is studied that p-BPA (p-bronophenylalanine) which formed complex with catechol functional group has interaction with epinephrine by {sup 11}B-NMR. Two {sup 11}B-NMR resonance signals were observed at pH 7.0. The signal at 29.6 ppm is assigned to p-BPA and at 10.8 ppm is assigned to that of complex. We can determine complex formation constants (logK') in various pH. (author)

An introduction to biological NMR spectroscopy

International Nuclear Information System (INIS)

Marion, Dominique

2013-01-01

NMR spectroscopy is a powerful tool for biologists interested in the structure, dynamics, and interactions of biological macromolecules. This review aims at presenting in an accessible manner the requirements and limitations of this technique. As an introduction, the history of NMR will highlight how the method evolved from physics to chemistry and finally to biology over several decades. We then introduce the NMR spectral parameters used in structural biology, namely the chemical shift, the J-coupling, nuclear Overhauser effects, and residual dipolar couplings. Resonance assignment, the required step for any further NMR study, bears a resemblance to jigsaw puzzle strategy. The NMR spectral parameters are then converted into angle and distances and used as input using restrained molecular dynamics to compute a bundle of structures. When interpreting a NMR-derived structure, the biologist has to judge its quality on the basis of the statistics provided. When the 3D structure is a priori known by other means, the molecular interaction with a partner can be mapped by NMR: information on the binding interface as well as on kinetic and thermodynamic constants can be gathered. NMR is suitable to monitor, over a wide range of frequencies, protein fluctuations that play a crucial role in their biological function. In the last section of this review, intrinsically disordered proteins, which have escaped the attention of classical structural biology, are discussed in the perspective of NMR, one of the rare available techniques able to describe structural ensembles. This Tutorial is part of the International Proteomics Tutorial Programme (IPTP 16 MCP). (authors)

N7- and N9-substituted purine derivatives: a N-15 NMR study

Czech Academy of Sciences Publication Activity Database

Marek, R.; Brus, Jiří; Toušek, J.; Kovács, L.; Hocková, Dana

2002-01-01

Roč. 40, č. 5 (2002), s. 353-360 ISSN 0749-1581 R&D Projects: GA ČR GA203/98/P026; GA MŠk LN00A016 Institutional research plan: CEZ:AV0Z4050913 Keywords : NMR * H-1 NMR * N-15 NMR Subject RIV: CE - Biochemistry Impact factor: 0.994, year: 2002

NMR experiments for resonance assignments of 13C, 15N doubly-labeled flexible polypeptides: Application to the human prion protein hPrP(23-230)

International Nuclear Information System (INIS)

Liu Aizhuo; Riek, Roland; Wider, Gerhard; Schroetter, Christine von; Zahn, Ralph; Wuethrich, Kurt

2000-01-01

A combination of three heteronuclear three-dimensional NMR experiments tailored for sequential resonance assignments in uniformly 15 N, 13 C-labeled flexible polypeptide chains is described. The 3D (H)N(CO-TOCSY)NH, 3D (H)CA(CO-TOCSY)NH and 3D (H)CBCA(CO-TOCSY)NH schemes make use of the favorable 15 N chemical shift dispersion in unfolded polypeptides, exploit the slow transverse 15 N relaxation rates of unfolded polypeptides in high resolution constant-time [ 1 H, 15 N]-correlation experiments, and use carbonyl carbon homonuclear isotropic mixing to transfer magnetization sequentially along the amino acid sequence. Practical applications are demonstrated with the 100-residue flexible tail of the recombinant human prion protein, making use of spectral resolution up to 0.6 Hz in the 15 N dimension, simultaneous correlation with the two adjacent amino acid residues to overcome problems associated with spectral overlap, and the potential of the presently described experiments to establish nearest-neighbor correlations across proline residues in the amino acid sequence

Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study

NARCIS (Netherlands)

Krause, Andre; Wu, Yu; Tian, Runtao; Beek, van Teris A.

2018-01-01

High-field NMR is an expensive and important quality control technique. In recent years, cheaper and simpler low-field NMR has become available as a new quality control technique. In this study, 60 MHz 1 H-NMR was compared with GC-MS and refractometry for the detection of adulteration of essential

NMR studies of liquid crystals and molecules dissolved in liquid crystal solvents

Energy Technology Data Exchange (ETDEWEB)

Drobny, Gary Peter [Univ. of California, Berkeley, CA (United States)

1982-11-01

This thesis describes several studies in which nuclear magnetic resonance (nmr) spectroscopy has been used to probe the structure, orientation and dynamics of liquid crystal mesogens and molecules dissolved in liquid crystalline phases. In addition, a modern high field nmr spectrometer is described which has been used to perform such nmr studies. Chapter 1 introduces the quantum mechanical formalisms used throughout this thesis and briefly reviews the fundamentals of nuclear spin physics and pulsed nmr spectroscopy. First the density operator is described and a specific form for the canonical ensemble is derived. Then Clebsch-Gordon coefficients, Wigner rotation matrices, and irreducible tensor operators are reviewed. An expression for the equilibrium (Curie) magnetization is obtained and the linear response of a spin system to a strong pulsed r.f. irradiation is described. Finally, the spin interaction Hamiltonians relevant to this work are reviewed together with their truncated forms. Chapter 2 is a deuterium magnetic resonance study of two 'nom' liquid crystals which possess several low temperature mesomorphic phases. Specifically, deuterium quadrupolar echo spectroscopy is used to determine the orientation of the liquid crystal molecules in smectic phases, the changes in molecular orientation and motion that occur at smectic-smectic phase transitions, and the order of the phase transitions. For both compounds, the phase sequence is determined to be isotropic, nematic, smectic A, smectic C, smectic B_A, smectic B_C, and crystalline. The structure of the smectic A phase is found to be consistent with the well-known model of a two dimensional liquid in which molecules are rapidly rotating about their long axes and oriented at right angles to the plane of the layers. Molecules in the smectic C phase are found to have their long axes tilted with respect to the layer normal, and the tilt angle is temperature dependent, increasing from

Standardizing the experimental conditions for using urine in NMR-based metabolomic studies with a particular focus on diagnostic studies: a review

KAUST Repository

Emwas, Abdul-Hamid M.

2014-11-21

The metabolic composition of human biofluids can provide important diagnostic and prognostic information. Among the biofluids most commonly analyzed in metabolomic studies, urine appears to be particularly useful. It is abundant, readily available, easily stored and can be collected by simple, noninvasive techniques. Moreover, given its chemical complexity, urine is particularly rich in potential disease biomarkers. This makes it an ideal biofluid for detecting or monitoring disease processes. Among the metabolomic tools available for urine analysis, NMR spectroscopy has proven to be particularly well-suited, because the technique is highly reproducible and requires minimal sample handling. As it permits the identification and quantification of a wide range of compounds, independent of their chemical properties, NMR spectroscopy has been frequently used to detect or discover disease fingerprints and biomarkers in urine. Although protocols for NMR data acquisition and processing have been standardized, no consensus on protocols for urine sample selection, collection, storage and preparation in NMR-based metabolomic studies have been developed. This lack of consensus may be leading to spurious biomarkers being reported and may account for a general lack of reproducibility between laboratories. Here, we review a large number of published studies on NMR-based urine metabolic profiling with the aim of identifying key variables that may affect the results of metabolomics studies. From this survey, we identify a number of issues that require either standardization or careful accounting in experimental design and provide some recommendations for urine collection, sample preparation and data acquisition.

Standardizing the experimental conditions for using urine in NMR-based metabolomic studies with a particular focus on diagnostic studies: a review

KAUST Repository

Emwas, Abdul-Hamid M.; Luchinat, Claudio; Turano, Paola; Tenori, Leonardo; Roy, Raja; Salek, Reza M.; Ryan, Danielle; Merzaban, Jasmeen; Kaddurah-Daouk, Rima; Zeri, Ana Carolina; Nagana Gowda, G. A.; Raftery, Daniel; Wang, Yulan; Brennan, Lorraine; Wishart, David S.

2014-01-01

The metabolic composition of human biofluids can provide important diagnostic and prognostic information. Among the biofluids most commonly analyzed in metabolomic studies, urine appears to be particularly useful. It is abundant, readily available, easily stored and can be collected by simple, noninvasive techniques. Moreover, given its chemical complexity, urine is particularly rich in potential disease biomarkers. This makes it an ideal biofluid for detecting or monitoring disease processes. Among the metabolomic tools available for urine analysis, NMR spectroscopy has proven to be particularly well-suited, because the technique is highly reproducible and requires minimal sample handling. As it permits the identification and quantification of a wide range of compounds, independent of their chemical properties, NMR spectroscopy has been frequently used to detect or discover disease fingerprints and biomarkers in urine. Although protocols for NMR data acquisition and processing have been standardized, no consensus on protocols for urine sample selection, collection, storage and preparation in NMR-based metabolomic studies have been developed. This lack of consensus may be leading to spurious biomarkers being reported and may account for a general lack of reproducibility between laboratories. Here, we review a large number of published studies on NMR-based urine metabolic profiling with the aim of identifying key variables that may affect the results of metabolomics studies. From this survey, we identify a number of issues that require either standardization or careful accounting in experimental design and provide some recommendations for urine collection, sample preparation and data acquisition.

Standardizing the experimental conditions for using urine in NMR-based metabolomic studies with a particular focus on diagnostic studies: a review.

Science.gov (United States)

Emwas, Abdul-Hamid; Luchinat, Claudio; Turano, Paola; Tenori, Leonardo; Roy, Raja; Salek, Reza M; Ryan, Danielle; Merzaban, Jasmeen S; Kaddurah-Daouk, Rima; Zeri, Ana Carolina; Nagana Gowda, G A; Raftery, Daniel; Wang, Yulan; Brennan, Lorraine; Wishart, David S

The metabolic composition of human biofluids can provide important diagnostic and prognostic information. Among the biofluids most commonly analyzed in metabolomic studies, urine appears to be particularly useful. It is abundant, readily available, easily stored and can be collected by simple, noninvasive techniques. Moreover, given its chemical complexity, urine is particularly rich in potential disease biomarkers. This makes it an ideal biofluid for detecting or monitoring disease processes. Among the metabolomic tools available for urine analysis, NMR spectroscopy has proven to be particularly well-suited, because the technique is highly reproducible and requires minimal sample handling. As it permits the identification and quantification of a wide range of compounds, independent of their chemical properties, NMR spectroscopy has been frequently used to detect or discover disease fingerprints and biomarkers in urine. Although protocols for NMR data acquisition and processing have been standardized, no consensus on protocols for urine sample selection, collection, storage and preparation in NMR-based metabolomic studies have been developed. This lack of consensus may be leading to spurious biomarkers being reported and may account for a general lack of reproducibility between laboratories. Here, we review a large number of published studies on NMR-based urine metabolic profiling with the aim of identifying key variables that may affect the results of metabolomics studies. From this survey, we identify a number of issues that require either standardization or careful accounting in experimental design and provide some recommendations for urine collection, sample preparation and data acquisition.

ECG gated NMR-CT for cardiovascular diseases

International Nuclear Information System (INIS)

Nishikawa, J.; Machida, K.; Iio, M.; Yoshimoto, N.; Sugimoto, T.; Kawaguchi, H.; Mano, H.

1984-01-01

The authors applied NMR-CT to cardiac study with ECG gated technique to evaluate the left ventricular (LV) function and compared it with cardiovascular nuclear medicine study (NM). The NMR-CT machine has resistive air-core magnet with 0.15 Tesla. The saturation recovery image or inversion recovery image were obtained as 256 x 256 matrix and 15 mm in thickness. The study population was ten patients who were evaluated both by NMR image and by NM performed within one week interval. The heart muscle was able to be visualized without any contrast material nor radioisotopes in inversion recovery images, whereas saturation recovery images failed to separate heart muscle from blood pool. The wall motions of LV in both methods were well correlated except for inferior wall. The values of ejection fraction in NMR image were moderately low, but two modalities showed satisfactory correlation (r=0.85). The region of myocardial infarction was revealed as wall thinning and/or wall motion abnormality. It is still preliminary to draw a conclusion, however, it can be said that in the evaluation of LV function, method by NMR might be of equal value to those of NM. It can be certain that eventually gated NMR-CT will become more effective method for various aspects of cardiovascular evaluation

In situ NMR and modeling studies of nitroxide mediated copolymerization of styrene and n-butyl acrylate

NARCIS (Netherlands)

Hlalele, L.; Klumperman, L.

2011-01-01

The combination of in situ1H NMR and in situ31P NMR was used to study the nitroxide mediated copolymerization of styrene and n-butyl acrylate. The alkoxyamine MAMA-DEPN was employed to initiate and mediate the copolymerization. The nature of the ultimate/terminal monomer units of dormant polymer

NMR imaging and pharmaceutical sciences

International Nuclear Information System (INIS)

Beall, P.T.; Good, W.R.

1986-01-01

Described is the technique of NMR-imaging in diagnostic medicine. Proton and phosphorus NMR in diagnosis of abnormal tissue pathology. Discussed is the value of NMR to the pharmaceutical sciences. NMR may play an important role in monitoring the response of tissues to drugs, determining the localization of drugs, performing real time pharmacokinetics and testing the use of NMR contrast pharmaceuticals

Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

Energy Technology Data Exchange (ETDEWEB)

Jelinek, Raz [Univ. of California, Berkeley, CA (United States)

1993-07-01

Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. ²⁷Al and ²³Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework ²⁷Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na⁺ cations are directly involved in adsorption processes and reactions in zeolite cavities.

Structural studies on leukaemia inhibitory factor

Energy Technology Data Exchange (ETDEWEB)

Norton, R.S.; Maurer, T.; Smith, D.K. [Biomolecular Research Institute, Parville (Australia); Nicola, N.A. [Institute of Medical Research, Melbourne (Australia)

1994-12-01

Leukaemia Inhibitory Factor (LIF) is a pleiotropic cytokine that acts on a wide range of target cells, including mega-karyocytes, osteoblasts, hepatocytes, adipocytes, neurons, embryonic stem cells, and primordial germ cells. Many of its activities are shared with other cytokines, particularly interleukin-6, oncostatin-M, ciliary neurotrophic factor, and granulocyte colony-stimulating factor (G-CSF). Although secreted in vivo as a glycoprotein, nonglycosylated recombinant protein expressed in E. coli is fully active and has been used in our nuclear magnetic resonance (NMR) studies of the three-dimensional structure and structure-function relationships of LIF. With 180 amino acids and a molecular mass of about 20 kDa, OF is too large for direct structure determination by two-dimensional and three-dimensional {sup 1}HNMR. It is necessary to label the protein with the stable isotopes {sup 15}N and {sup 13}C and employ heteronuclear three-dimensional NMR in order to resolve and interpret the spectral information required for three-dimensional structure determination. This work has been undertaken with both human LIF and a mouse-human chimaera that binds to the human LIF receptor with the same affinity as the human protein and yet expresses in E. coli at much higher levels. Sequence-specific resonance assignments and secondary structure elements for these proteins will be presented and progress towards determination of their three-dimensional structures described.

Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

Directory of Open Access Journals (Sweden)

Sondes Bouabdallah

2014-01-01

Full Text Available The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (ΔH, ΔS, and ΔG were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations.

Some double resonance and multiple quantum NMR studies in solids

International Nuclear Information System (INIS)

Wemmer, D.E.

1978-08-01

The first section of this work presents the theory and experimental applications to analysis of molecular motion of chemical shielding lineshapes obtained with high resolution double resonance NMR techniques. Analysis of 13 C powder lineshapes in hexamethylbenzene (HMB) and decamethylferrocene (DMFe) show that these molecules reorient in a jumping manner about the symmetry axis. Analysis of proton chemical shielding lineshapes of residual protons in heavy ice (D 2 O) show that protons are exchanged among the tetrahedral positions of neighboring oxygen atoms, consistent with motion expected from defect migration. The second section describes the application of Fourier Transform Double Quantum NMR to measurement of chemical shielding of deuterium in powder samples. Studies of partially deuterated benzene and ferrocene give equal shielding anisotropies, Δsigma = -6.5 ppM. Theoretical predictions and experimental measurements of dipolar couplings between deuterons using FTDQ NMR are presented. Crystals of BaClO 3 .D 2 O, α,β d-2 HMB and α,β,γ d-3 HMB were studied, as were powders of d-2 HMB and anisic acid. The third section discusses general multiple quantum spectroscopy in dipolar coupled spin systems. Theoretical description is made for creation and detection of coherences between states without quantum number selection rules Δm = +-1. Descriptions of techniques for partial selectivity of order in preparation and detection of multiple quantum coherences are made. The effects on selectivity and resolution of echo pulses during multiple quantum experiments are discussed. Experimental observation of coherences up to order 6 have been made in a sample of benzene dissolved in a liquid crystal. Experimental verifications of order selection and echo generation have been made

Structural variation study of cobalt nanoparticles synthesized by co-precipitation method using 59Co NMR

Science.gov (United States)

Manjunatha, M.; Kumar, Rajeev; B. M., Siddesh; Sahoo, Balaram; Damle, R.; Ramesh, K. P.

2018-04-01

We have synthesized cobalt nanoparticles using co-precipitation method. Further, the two phases of the cobalt is monitored by varying the synthesis parameters. 59Co NMR and XRD are used as characterization tools to study the phase variation in the cobalt samples. XRD and NMR results show a remarkable correlation in the two samples (Co-1 and Co-2). Co-2 has predominant fcc and hcp phases, whereas, Co-1 has fcc phase with lower amount of hcp. Both the samples show same saturation magnetization (Ms) but there is a remarkable difference in the phase composition. Thus, 59Co NMR appears to be a good tool to identify the phase purity of the ferromagnetic cobalt samples.

Theory of NMR probe design

International Nuclear Information System (INIS)

Schnall, M.D.

1988-01-01

The NMR probe is the intrinsic part of the NMR system which allows transmission of a stimulus to a sample and the reception of a resulting signal from a sample. NMR probes are used in both imaging and spectroscopy. Optimal probe design is important to the production of adequate signal/moise. It is important for anyone using NMR techniques to understand how NMR probes work and how to optimize probe design

$\\beta$-NMR of copper isotopes in ionic liquids

CERN Multimedia

We propose to test the feasibility of spin-polarization and $\\beta$-NMR studies on several short-lived copper isotopes, $^{58}$ Cu, $^{74}$Cu and $^{75}$Cu in crystals and liquids. The motivation is given by biological studies of Cu with $\\beta$-NMR in liquid samples, since Cu is present in a large number of enzymes involved in electron transfer and activation of oxygen. The technique is based on spin-polarization via optical pumping in the new VITO beamline. We will use the existing lasers, NMR magnet and NMR chambers and we will prepare a new optical pumping system. The studies will be devoted to tests of achieved $\\beta$-asymmetry in solid hosts, the behaviour of asymmetry when increasing vacuum, and finally NMR scans in ionic liquids. The achieved spin polarization will be also relevant for the plans to measure with high precision the magnetic moments of neutron-rich Cu isotopes.

NMR studies of myocardial energy metabolism and ionic homeostasis during ischemia and reperfusion

International Nuclear Information System (INIS)

Kirkels, J.H.

1989-01-01

In this study several aspects of myocardial energy metabolism and ionic homeostasis during ischemia and reperfusion were investigated in isolated perfused rat hearts, regionally ischemic rabbit hearts, and ex vivo human donor hearts during long term hypothermic cardioplegia. Phosphorus-31 nuclear magnetic resonance ( 31 P NMR) spectroscopy was used as a powerful tool to non-destructively follow the time course in changes in intracellular high-energy phosphates, (creatine phosphate and ATP), inorganic phosphate, and pH. In addition, changes in intracellular free magnesium were followed during ischemia and reperfusion. Sodium-23 ( 23 Na) NMR spectroscopy was used to study intracellular sodium during ischemia and reperfusion and during calcium-free perfusion. (author). 495 refs.; 33 figs.; 11 tabs

Quantum tunneling of magnetization in molecular nanomagnet Fe8 studied by NMR

International Nuclear Information System (INIS)

Maegawa, Satoru; Ueda, Miki

2003-01-01

Magnetization and NMR measurements have been performed for single crystals of molecular magnet Fe8. The field and temperature dependences of magnetization below 25 K are well described in terms of the isolated clusters with the total spin S=10. The stepwise recoveries of 1 H-NMR signals at the level crossing fields caused by the resonant quantum tunneling of magnetization were observed below 400 mK. The recovery of the NMR signals are explained by the fluctuation caused by the transition between the energy states of Fe magnetizations governed by Landau-Zener quantum transitions

Structural study of the membrane protein MscL using cell-free expression and solid-state NMR

Science.gov (United States)

Abdine, Alaa; Verhoeven, Michiel A.; Park, Kyu-Ho; Ghazi, Alexandre; Guittet, Eric; Berrier, Catherine; Van Heijenoort, Carine; Warschawski, Dror E.

2010-05-01

High-resolution structures of membrane proteins have so far been obtained mostly by X-ray crystallography, on samples where the protein is surrounded by detergent. Recent developments of solid-state NMR have opened the way to a new approach for the study of integral membrane proteins inside a membrane. At the same time, the extension of cell-free expression to the production of membrane proteins allows for the production of proteins tailor made for NMR. We present here an in situ solid-state NMR study of a membrane protein selectively labeled through the use of cell-free expression. The sample consists of MscL (mechano-sensitive channel of large conductance), a 75 kDa pentameric α-helical ion channel from Escherichia coli, reconstituted in a hydrated lipid bilayer. Compared to a uniformly labeled protein sample, the spectral crowding is greatly reduced in the cell-free expressed protein sample. This approach may be a decisive step required for spectral assignment and structure determination of membrane proteins by solid-state NMR.

Conformations and Intermolecular Interactions in Cellulose/Silk Fibroin Blend Films: A Solid-State NMR Perspective.

Science.gov (United States)

Tian, Donglin; Li, Tao; Zhang, Rongchun; Wu, Qiang; Chen, Tiehong; Sun, Pingchuan; Ramamoorthy, Ayyalusamy

2017-06-29

Fabricating materials with excellent mechanical performance from the natural renewable and degradable biopolymers has drawn significant attention in recent decades due to the environmental concerns and energy crisis. As two of the most promising substitutes of synthetic polymers, silk fibroin (SF), and cellulose, have been widely used in the field of textile, biomedicine, biotechnology, etc. Particularly, the cellulose/SF blend film exhibits better strength and toughness than that of regenerated cellulose film. Herein, this study is aimed to understand the molecular origin of the enhanced mechanical properties for the cellulose/SF blend film, using solid-state NMR as a main tool to investigate the conformational changes, intermolecular interactions between cellulose and SF and the water organization. It is found that the content of the β-sheet structure is increased in the cellulose/SF blend film with respect to the regenerated SF film, accompanied by the reduction of the content of random coil structures. In addition, the strong hydrogen bonding interaction between the SF and cellulose is clearly elucidated by the two-dimensional (2D) 1 H- 13 C heteronuclear correlation (HETCOR) NMR experiments, demonstrating that the SF and cellulose are miscible at the molecular level. Moreover, it is also found that the -NH groups of SF prefer to form hydrogen bonds with the hydroxyl groups bonded to carbons C2 and C3 of cellulose, while the hydroxyl groups bonded to carbon C6 and the ether oxygen are less favorable for hydrogen bonding interactions with the -NH groups of SF. Interestingly, bound water is found to be present in the air-dried cellulose/SF blend film, which is predominantly associated with the cellulose backbones as determined by 2D 1 H- 13 C wide-line-separation (WISE) experiments with spin diffusion. This clearly reveals the presence of nanoheterogeneity in the cellulose/SF blend film, although cellulose and SF are miscible at a molecular level. Without doubt

NMR and computational study of Ba8CuxGe46-x clathrate semiconductors

International Nuclear Information System (INIS)

Chen, Jing-Han; Sirusi Arvij, Ali; Zheng, Xiang; Rodriguez, Sergio Y.; Ross, Joseph H.

2014-01-01

Highlights: • Quadrupole NMR with first-principles calculations probes local site preferences. • Cu/Ge ratio is clarified vs. the ideal Zintl composition. • Modified Becke–Johnson exchange potential agrees well with NMR Knight shifts. - Abstract: Ba 8 Cu x Ge 46-x is a type-I clathrate material that forms as a semiconductor in a narrow composition range corresponding to the electron-balanced Zintl composition, with x = 5.3. We use NMR spectroscopy combined with ab initio electronic structure calculations to probe the electronic and structural behavior of these materials. Computational results based on a superstructure model for the atomic configuration of the alloy provide good agreement with the electric quadrupole-broadened NMR lineshapes. Modeling using the modified Becke–Johnson (TB-mBJ) exchange potential is also shown to agree well with experimental NMR Knight shifts. The results indicate that the Cu–Ge balance is the main factor determining the carrier density, within a narrow stability range near the ideal Zintl composition

Studies on supramolecular gel formation using DOSY NMR

Czech Academy of Sciences Publication Activity Database

Nonappa, N.; Šaman, David; Kolehmainen, E.

2015-01-01

Roč. 53, č. 4 (2015), s. 256-260 ISSN 0749-1581 Institutional support: RVO:61388963 Keywords : DOSY * VT NMR * gel * diffusion coefficients Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.226, year: 2015

The structure of poly(carbonsuboxide) on the atomic scale: a solid-state NMR study.

Science.gov (United States)

Schmedt auf der Günne, Jörn; Beck, Johannes; Hoffbauer, Wilfried; Krieger-Beck, Petra

2005-07-18

In this contribution we present a study of the structure of amorphous poly(carbonsuboxide) (C3O2)x by 13C solid-state NMR spectroscopy supported by infrared spectroscopy and chemical analysis. Poly(carbonsuboxide) was obtained by polymerization of carbonsuboxide C3O2, which in turn was synthesized from malonic acid bis(trimethylsilylester). Two different 13C labeling schemes were applied to probe inter- and intramonomeric bonds in the polymer by dipolar solid-state NMR methods and also to allow quantitative 13C MAS NMR spectra. Four types of carbon environments can be distinguished in the NMR spectra. Double-quantum and triple-quantum 2D correlation experiments were used to assign the observed peaks using the through-space and through-bond dipolar coupling. In order to obtain distance constraints for the intermonomeric bonds, double-quantum constant-time experiments were performed. In these experiments an additional filter step was applied to suppress contributions from not directly bonded 13C,13C spin pairs. The 13C NMR intensities, chemical shifts, connectivities and distances gave constraints for both the polymerization mechanism and the short-range order of the polymer. The experimental results were complemented by bond lengths predicted by density functional theory methods for several previously suggested models. Based on the presented evidence we can unambiguously exclude models based on gamma-pyronic units and support models based on alpha-pyronic units. The possibility of planar ladder- and bracelet-like alpha-pyronic structures is discussed.

Petrophysical properties of greensand as predicted from NMR measurements

DEFF Research Database (Denmark)

Hossain, Zakir; Grattoni, Carlos A.; Solymar, Mikael

2011-01-01

ABSTRACT: Nuclear magnetic resonance (NMR) is a useful tool in reservoir evaluation. The objective of this study is to predict petrophysical properties from NMR T2 distributions. A series of laboratory experiments including core analysis, capillary pressure measurements, NMR T2 measurements...... with macro-pores. Permeability may be predicted from NMR by using Kozeny's equation when surface relaxivity is known. Capillary pressure drainage curves may be predicted from NMR T2 distribution when pore size distribution within a sample is homogeneous....

Local electronic structure of TM-based alloys: a pulsed NMR study

International Nuclear Information System (INIS)

Guerra, D.A.

1984-01-01

A pulsed NMR study on several transition metal + metalloid amorphous alloys is reported. The analisis of Knight shifts and nuclear spin-lattice relaxation of metalloids indicates a dominant contribution of p-electrons in the Fermi level density of state, supporting the existence of a p-d hibridization. (author) [pt

nmrML: A Community Supported Open Data Standard for the Description, Storage, and Exchange of NMR Data.

Science.gov (United States)

Schober, Daniel; Jacob, Daniel; Wilson, Michael; Cruz, Joseph A; Marcu, Ana; Grant, Jason R; Moing, Annick; Deborde, Catherine; de Figueiredo, Luis F; Haug, Kenneth; Rocca-Serra, Philippe; Easton, John; Ebbels, Timothy M D; Hao, Jie; Ludwig, Christian; Günther, Ulrich L; Rosato, Antonio; Klein, Matthias S; Lewis, Ian A; Luchinat, Claudio; Jones, Andrew R; Grauslys, Arturas; Larralde, Martin; Yokochi, Masashi; Kobayashi, Naohiro; Porzel, Andrea; Griffin, Julian L; Viant, Mark R; Wishart, David S; Steinbeck, Christoph; Salek, Reza M; Neumann, Steffen

2018-01-02

NMR is a widely used analytical technique with a growing number of repositories available. As a result, demands for a vendor-agnostic, open data format for long-term archiving of NMR data have emerged with the aim to ease and encourage sharing, comparison, and reuse of NMR data. Here we present nmrML, an open XML-based exchange and storage format for NMR spectral data. The nmrML format is intended to be fully compatible with existing NMR data for chemical, biochemical, and metabolomics experiments. nmrML can capture raw NMR data, spectral data acquisition parameters, and where available spectral metadata, such as chemical structures associated with spectral assignments. The nmrML format is compatible with pure-compound NMR data for reference spectral libraries as well as NMR data from complex biomixtures, i.e., metabolomics experiments. To facilitate format conversions, we provide nmrML converters for Bruker, JEOL and Agilent/Varian vendor formats. In addition, easy-to-use Web-based spectral viewing, processing, and spectral assignment tools that read and write nmrML have been developed. Software libraries and Web services for data validation are available for tool developers and end-users. The nmrML format has already been adopted for capturing and disseminating NMR data for small molecules by several open source data processing tools and metabolomics reference spectral libraries, e.g., serving as storage format for the MetaboLights data repository. The nmrML open access data standard has been endorsed by the Metabolomics Standards Initiative (MSI), and we here encourage user participation and feedback to increase usability and make it a successful standard.

Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR.

Science.gov (United States)

van der Schot, Gijs; Bonvin, Alexandre M J J

2015-08-01

We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on unassigned NOE lists (Huang et al. in J Am Chem Soc 127:1665-1674, 2005b, doi: 10.1021/ja047109h). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 with recalculated targets using the new R3FP fragment picker for fragment selection and implementing a new annotation of prediction reliability (van der Schot et al. in J Biomol NMR 57:27-35, 2013, doi: 10.1007/s10858-013-9762-6), both implemented in the CS-Rosetta3 WeNMR server. In this second round of CASD-NMR, the WeNMR CS-Rosetta server has demonstrated a much better performance than in the first round since only converged targets were submitted. Further, recalculation of all CASD-NMR targets using the new version of the server demonstrates that our new annotation of prediction quality is giving reliable results. Predictions annotated as weak are often found to provide useful models, but only for a fraction of the sequence, and should therefore only be used with caution.

31P-edited diffusion-ordered 1H NMR spectroscopy for the spectral isolation and identification of organophosphorus compounds related to chemical weapons agents and their degradation products.

Science.gov (United States)

Mayer, Brian P; Valdez, Carlos A; Hok, Saphon; Chinn, Sarah C; Hart, Bradley R

2012-12-04

Organophosphorus compounds represent a large class of molecules that include pesticides, flame-retardants, biologically relevant molecules, and chemical weapons agents (CWAs). The detection and identification of organophosphorus molecules, particularly in the cases of pesticides and CWAs, are paramount to the verification of international treaties by various organizations. To that end, novel analytical methodologies that can provide additional support to traditional analyses are important for unambiguous identification of these compounds. We have developed an NMR method that selectively edits for organophosphorus compounds via (31)P-(1)H heteronuclear single quantum correlation (HSQC) and provides an additional chromatographic-like separation based on self-diffusivities of the individual species via (1)H diffusion-ordered spectroscopy (DOSY): (1)H-(31)P HSQC-DOSY. The technique is first validated using the CWA VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) by traditional two-dimensional DOSY spectra. We then extend this technique to a complex mixture of VX degradation products and identify all the main phosphorus-containing byproducts generated after exposure to a zinc-cyclen organometallic homogeneous catalyst.

Nuclear magnetic resonance (NMR) tomography

International Nuclear Information System (INIS)

Skalpe, I.O.

1984-01-01

A brief survey of the working principle of the NMR technique in diagnostical medicine is given. Its clinical usefulness for locating tumors, diagnosing various other diseases, such as some mental illnesses and multiple sclerosis, and its possibilities for studying biochemical processes in vivo are mentioned. The price of NMR image scanners and the problems of the strong magnetic field around the machines are mentioned

Contact replacement for NMR resonance assignment.

Science.gov (United States)

Xiong, Fei; Pandurangan, Gopal; Bailey-Kellogg, Chris

2008-07-01

Complementing its traditional role in structural studies of proteins, nuclear magnetic resonance (NMR) spectroscopy is playing an increasingly important role in functional studies. NMR dynamics experiments characterize motions involved in target recognition, ligand binding, etc., while NMR chemical shift perturbation experiments identify and localize protein-protein and protein-ligand interactions. The key bottleneck in these studies is to determine the backbone resonance assignment, which allows spectral peaks to be mapped to specific atoms. This article develops a novel approach to address that bottleneck, exploiting an available X-ray structure or homology model to assign the entire backbone from a set of relatively fast and cheap NMR experiments. We formulate contact replacement for resonance assignment as the problem of computing correspondences between a contact graph representing the structure and an NMR graph representing the data; the NMR graph is a significantly corrupted, ambiguous version of the contact graph. We first show that by combining connectivity and amino acid type information, and exploiting the random structure of the noise, one can provably determine unique correspondences in polynomial time with high probability, even in the presence of significant noise (a constant number of noisy edges per vertex). We then detail an efficient randomized algorithm and show that, over a variety of experimental and synthetic datasets, it is robust to typical levels of structural variation (1-2 AA), noise (250-600%) and missings (10-40%). Our algorithm achieves very good overall assignment accuracy, above 80% in alpha-helices, 70% in beta-sheets and 60% in loop regions. Our contact replacement algorithm is implemented in platform-independent Python code. The software can be freely obtained for academic use by request from the authors.

Some double resonance and multiple quantum NMR studies in solids

Energy Technology Data Exchange (ETDEWEB)

Wemmer, D.E.

1978-08-01

The first section of this work presents the theory and experimental applications to analysis of molecular motion of chemical shielding lineshapes obtained with high resolution double resonance NMR techniques. Analysis of /sup 13/C powder lineshapes in hexamethylbenzene (HMB) and decamethylferrocene (DMFe) show that these molecules reorient in a jumping manner about the symmetry axis. Analysis of proton chemical shielding lineshapes of residual protons in heavy ice (D/sub 2/O) show that protons are exchanged among the tetrahedral positions of neighboring oxygen atoms, consistent with motion expected from defect migration. The second section describes the application of Fourier Transform Double Quantum NMR to measurement of chemical shielding of deuterium in powder samples. Studies of partially deuterated benzene and ferrocene give equal shielding anisotropies, ..delta..sigma = -6.5 ppM. Theoretical predictions and experimental measurements of dipolar couplings between deuterons using FTDQ NMR are presented. Crystals of BaClO/sub 3/.D/sub 2/O, ..cap alpha..,..beta.. d-2 HMB and ..cap alpha..,..beta..,..gamma.. d-3 HMB were studied, as were powders of d-2 HMB and anisic acid. The third section discusses general multiple quantum spectroscopy in dipolar coupled spin systems. Theoretical description is made for creation and detection of coherences between states without quantum number selection rules ..delta..m = +-1. Descriptions of techniques for partial selectivity of order in preparation and detection of multiple quantum coherences are made. The effects on selectivity and resolution of echo pulses during multiple quantum experiments are discussed. Experimental observation of coherences up to order 6 have been made in a sample of benzene dissolved in a liquid crystal. Experimental verifications of order selection and echo generation have been made.

Identification of Hepatoprotective Constituents in Limonium tetragonum and Development of Simultaneous Analysis Method using High-performance Liquid Chromatography

Science.gov (United States)

Lee, Jae Sun; Kim, Yun Na; Kim, Na-Hyun; Heo, Jeong-Doo; Yang, Min Hye; Rho, Jung-Rae; Jeong, Eun Ju

2017-01-01

Background: Limonium tetragonum, a naturally salt-tolerant halophyte, has been studied recently and is of much interest to researchers due to its potent antioxidant and hepatoprotective activities. Objective: In the present study, we attempted to elucidate bioactive compounds from ethyl acetate (EtOAc) soluble fraction of L. tetragonum extract. Furthermore, the simultaneous analysis method of bioactive EtOAc fraction of L. tetragonum has been developed using high-performance liquid chromatography (HPLC). Materials and Methods: Thirteen compounds have been successfully isolated from EtOAc fraction of L. tetragonum, and the structures of 1–13 were elucidated by extensive one-dimensional and two-dimensional spectroscopic methods including 1H-NMR, 13C-NMR, 1H-1H COSY, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, and nuclear Overhauser effect spectroscopy. Hepatoprotection of the isolated compounds against liver fibrosis was evaluated by measuring inhibition on hepatic stellate cells (HSCs) undergoing proliferation. Results: Compounds 1–13 were identified as gallincin (1), apigenin-3-O-β-D-galactopyranoside (2), quercetin (3), quercetin-3-O-β-D-galactopyranoside (4), (−)-epigallocatechin (5), (−)-epigallocatechin-3-gallate (6), (−)-epigallocatechin-3-(3″-O-methyl) gallate (7), myricetin-3-O-β-D-galactopyranoside (8), myricetin-3-O-(6″-O-galloyl)-β-D-galactopyranoside (9), myricetin-3-O-α-L-rhamnopyranoside (10), myricetin-3-O-(2″-O-galloyl)-α-L-rhamnopyranoside (11), myricetin-3-O-(3″-O-galloyl)-α-L-rhamnopyranoside (12), and myricetin-3-O-α-L-arabinopyranoside (13), respectively. All compounds except for 4, 8, and 10 are reported for the first time from this plant. Conclusion: Myricetin glycosides which possess galloyl substituent (9, 11, and 12) showed most potent inhibitory effects on the proliferation of HSCs. SUMMARY In the present study, we have successfully isolated 13 compounds from bioactive fraction

Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR

NARCIS (Netherlands)

Van Der Schot, Gijs; Bonvin, Alexandre M J J

We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on

Application of amino acid type-specific 1H- and 14N-labeling in a 2H-, 15N-labeled background to a 47 kDa homodimer: Potential for NMR structure determination of large proteins

International Nuclear Information System (INIS)

Kelly, Mark J.S.; Krieger, Cornelia; Ball, Linda J.; Yu Yihua; Richter, Gerald; Schmieder, Peter; Bacher, Adelbert; Oschkinat, Hartmut

1999-01-01

NMR investigations of larger macromolecules (>20 kDa) are severely hindered by rapid 1H and 13C transverse relaxation. Replacement of non-exchangeable protons with deuterium removes many efficient 1H-1H and 1H-13C relaxation pathways. The main disadvantage of deuteration is that many of the protons which would normally be the source of NOE-based distance restraints are removed. We report the development of a novel labeling strategy which is based on specific protonation and 14N-labeling of the residues phenylalanine, tyrosine, threonine, isoleucine and valine in a fully deuterated, 15N-labeled background. This allows the application of heteronuclear half-filters, 15N-editing and 1H-TOCSY experiments to select for particular magnetization transfer pathways. Results from investigations of a 47 kDa dimeric protein labeled in this way demonstrated that the method provides useful information for the structure determination of large proteins

Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR

Energy Technology Data Exchange (ETDEWEB)

Schot, Gijs van der [Uppsala University, Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology (Sweden); Bonvin, Alexandre M. J. J., E-mail: a.m.j.j.bonvin@uu.nl [Utrecht University, Faculty of Science – Chemistry, Bijvoet Center for Biomolecular Research (Netherlands)

2015-08-15

We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on unassigned NOE lists (Huang et al. in J Am Chem Soc 127:1665–1674, 2005b, doi: 10.1021/ja047109h 10.1021/ja047109h ). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 with recalculated targets using the new R3FP fragment picker for fragment selection and implementing a new annotation of prediction reliability (van der Schot et al. in J Biomol NMR 57:27–35, 2013, doi: 10.1007/s10858-013-9762-6 10.1007/s10858-013-9762-6 ), both implemented in the CS-Rosetta3 WeNMR server. In this second round of CASD-NMR, the WeNMR CS-Rosetta server has demonstrated a much better performance than in the first round since only converged targets were submitted. Further, recalculation of all CASD-NMR targets using the new version of the server demonstrates that our new annotation of prediction quality is giving reliable results. Predictions annotated as weak are often found to provide useful models, but only for a fraction of the sequence, and should therefore only be used with caution.

Performance of the WeNMR CS-Rosetta3 web server in CASD-NMR

International Nuclear Information System (INIS)

Schot, Gijs van der; Bonvin, Alexandre M. J. J.

2015-01-01

We present here the performance of the WeNMR CS-Rosetta3 web server in CASD-NMR, the critical assessment of automated structure determination by NMR. The CS-Rosetta server uses only chemical shifts for structure prediction, in combination, when available, with a post-scoring procedure based on unassigned NOE lists (Huang et al. in J Am Chem Soc 127:1665–1674, 2005b, doi: 10.1021/ja047109h 10.1021/ja047109h ). We compare the original submissions using a previous version of the server based on Rosetta version 2.6 with recalculated targets using the new R3FP fragment picker for fragment selection and implementing a new annotation of prediction reliability (van der Schot et al. in J Biomol NMR 57:27–35, 2013, doi: 10.1007/s10858-013-9762-6 10.1007/s10858-013-9762-6 ), both implemented in the CS-Rosetta3 WeNMR server. In this second round of CASD-NMR, the WeNMR CS-Rosetta server has demonstrated a much better performance than in the first round since only converged targets were submitted. Further, recalculation of all CASD-NMR targets using the new version of the server demonstrates that our new annotation of prediction quality is giving reliable results. Predictions annotated as weak are often found to provide useful models, but only for a fraction of the sequence, and should therefore only be used with caution

Interaction of charged amphiphilic drugs with phosphatidylcholine vesicles studied by NMR

International Nuclear Information System (INIS)

Eriksson, L.E.G.

1987-01-01

Small unilamellar vesicles from egg phosphatidylcholine in NaCl solutions were exposed to some amphiphilic pharmaca. The aromatic drugs (chlorpromazine, dibucaine, tetracaine, imipramine and propranolol) were in their cationic form of the amines. By 1 H- and 31 P-NMR the membrane signals were observed. In particular, the N-methyl choline proton signals were followed upon drug addition. The intrinsic chemical shift difference (0.02 ppm) between the inner (upfield) and outer choline signals was influenced by the drug concentration. Packing properties of the lipid head groups and ring current shift probably contributed. At very high drug concentration, the vesicles are destroyed. A transformation into a micellar state with a high sample viscosity took place in a narrow concentration range of drug. The anion effects of Cl - were studied from the 35 Cl-NMR linewidth at 9.8 and 39.1 MHz. A continuous increase in the signal linewidth followed upon drug addition to the vesicles. Only chlorpromazine produced a broadening in the absence of vesicles (NaCl blank). The linewidth reflected a critical micelle concentration of this drug around 7 mM in 0.1 M NaCl. The 35 Cl-NMR experiments demonstrated the existence of an anionic counterion effect. This phenomenon should be accounted for when quantitatively analysing drug-membrane interactions in electrostatic terms. (Auth.)

Antiinflammatory and Antioxidant Flavonoids and Phenols from Cardiospermum halicacabum (倒地鈴 Dào Dì Líng

Directory of Open Access Journals (Sweden)

Hui-Ling Cheng

2013-01-01

Full Text Available Seventeen compounds, quercetin-3-O-α-l-rhamnoside (1, kaempferol-3-O-α-l-rhamnoside (2, apigenin-7-O-β-d-glucuronide (3, apigenin 7-O-β-d-glucuronide methyl ester (4, apigenin 7-O-β-d-glucuronide ethyl ester (5, chrysoeriol (6, apigenin (7, kaempferol (8, luteolin (9, quercetin (10, methyl 3,4-dihydroxybenzoate (11, p-coumaric acid (12, 4-hydroxybenzoic acid (13, hydroquinone (14, protocathehuic acid (15, gallic acid (16, and indole-3-carboxylic acid (17, were isolated from the ethanol extract of Taiwanese Cardiospermum halicabum. All chemical structures were determined by physical and extensive spectroscopic analyses such as 1H Nuclear Magnetic Resonance spectroscopy (NMR, 13C NMR, 1H-1H Correlation spectroscopy (1H-1H COSY, Heteronuclear Multiple Quantum Coherence spectroscopy (HMQC, Heteronuclear Multiple-bond Correlation spectroscopy (HMBC, and Nuclear Overhauser Effect spectroscopy (NOESY, as well as comparison with literature values. Furthermore, the High-Performance Liquid Chromatography-Photodiode Array Detector (HPLC-DAD fingerprint profile was established for the determination of major constituents in the EtOAc extract and retention times of the isolated compounds. All isolated compounds were also evaluated for antiinflammatory and antioxidant activities.

Dynamic pulsed-field-gradient NMR

CERN Document Server

Sørland, Geir Humborstad

2014-01-01

Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

NMR 1H,13C, 15N backbone and 13C side chain resonance assignment of the G12C mutant of human K-Ras bound to GDP.

Science.gov (United States)

Sharma, Alok K; Lee, Seung-Joo; Rigby, Alan C; Townson, Sharon A

2018-05-02

K-Ras is a key driver of oncogenesis, accounting for approximately 80% of Ras-driven human cancers. The small GTPase cycles between an inactive, GDP-bound and an active, GTP-bound state, regulated by guanine nucleotide exchange factors and GTPase activating proteins, respectively. Activated K-Ras regulates cell proliferation, differentiation and survival by signaling through several effector pathways, including Raf-MAPK. Oncogenic mutations that impair the GTPase activity of K-Ras result in a hyperactivated state, leading to uncontrolled cellular proliferation and tumorogenesis. A cysteine mutation at glycine 12 is commonly found in K-Ras associated cancers, and has become a recent focus for therapeutic intervention. We report here 1 H N, 15 N, and 13 C resonance assignments for the 19.3 kDa (aa 1-169) human K-Ras protein harboring an oncogenic G12C mutation in the GDP-bound form (K-RAS G12C-GDP ), using heteronuclear, multidimensional NMR spectroscopy. Backbone 1 H- 15 N correlations have been assigned for all non-proline residues, except for the first methionine residue.

Single crystal NMR studies of high temperature superconductors

International Nuclear Information System (INIS)

Pennington, C.H.; Durand, D.J.; Zax, D.B.; Slichter, C.P.; Rice, J.P.; Bukowski, E.D.; Ginsberg, D.M.

1989-01-01

The authors report Cu NMR studies in the normal state of a single crystal of the T/sub c/ = 90 K superconductor YBa 2 Cu 3 O/sub 7/minus/δ/. The authors have measured the magnetic shift tensor, the electric field gradient tensor, the nuclear spin-lattice relaxation rate tensor, and the time dependence and functional form of the transverse decay. From these data they obtain information about the charge state and magnetic state of the Cu atoms, and the existence and size of the electronic exchange coupling between spins of adjacent Cu atoms. 18 refs., 3 figs., 2 tabs

NMR shielding calculations across the periodic table: diamagnetic uranium compounds. 2. Ligand and metal NMR.

Science.gov (United States)

Schreckenbach, Georg

2002-12-16

In this and a previous article (J. Phys. Chem. A 2000, 104, 8244), the range of application for relativistic density functional theory (DFT) is extended to the calculation of nuclear magnetic resonance (NMR) shieldings and chemical shifts in diamagnetic actinide compounds. Two relativistic DFT methods are used, ZORA ("zeroth-order regular approximation") and the quasirelativistic (QR) method. In the given second paper, NMR shieldings and chemical shifts are calculated and discussed for a wide range of compounds. The molecules studied comprise uranyl complexes, [UO(2)L(n)](+/-)(q); UF(6); inorganic UF(6) derivatives, UF(6-n)Cl(n), n = 0-6; and organometallic UF(6) derivatives, UF(6-n)(OCH(3))(n), n = 0-5. Uranyl complexes include [UO(2)F(4)](2-), [UO(2)Cl(4)](2-), [UO(2)(OH)(4)](2-), [UO(2)(CO(3))(3)](4-), and [UO(2)(H(2)O)(5)](2+). For the ligand NMR, moderate (e.g., (19)F NMR chemical shifts in UF(6-n)Cl(n)) to excellent agreement [e.g., (19)F chemical shift tensor in UF(6) or (1)H NMR in UF(6-n)(OCH(3))(n)] has been found between theory and experiment. The methods have been used to calculate the experimentally unknown (235)U NMR chemical shifts. A large chemical shift range of at least 21,000 ppm has been predicted for the (235)U nucleus. ZORA spin-orbit appears to be the most accurate method for predicting actinide metal chemical shifts. Trends in the (235)U NMR chemical shifts of UF(6-n)L(n) molecules are analyzed and explained in terms of the calculated electronic structure. It is argued that the energy separation and interaction between occupied and virtual orbitals with f-character are the determining factors.

Characterization of the Raf kinase inhibitory protein (RKIP) binding pocket: NMR-based screening identifies small-molecule ligands.

Science.gov (United States)

Shemon, Anne N; Heil, Gary L; Granovsky, Alexey E; Clark, Mathew M; McElheny, Dan; Chimon, Alexander; Rosner, Marsha R; Koide, Shohei

2010-05-05

Raf kinase inhibitory protein (RKIP), also known as phoshaptidylethanolamine binding protein (PEBP), has been shown to inhibit Raf and thereby negatively regulate growth factor signaling by the Raf/MAP kinase pathway. RKIP has also been shown to suppress metastasis. We have previously demonstrated that RKIP/Raf interaction is regulated by two mechanisms: phosphorylation of RKIP at Ser-153, and occupation of RKIP's conserved ligand binding domain with a phospholipid (2-dihexanoyl-sn-glycero-3-phosphoethanolamine; DHPE). In addition to phospholipids, other ligands have been reported to bind this domain; however their binding properties remain uncharacterized. In this study, we used high-resolution heteronuclear NMR spectroscopy to screen a chemical library and assay a number of potential RKIP ligands for binding to the protein. Surprisingly, many compounds previously postulated as RKIP ligands showed no detectable binding in near-physiological solution conditions even at millimolar concentrations. In contrast, we found three novel ligands for RKIP that specifically bind to the RKIP pocket. Interestingly, unlike the phospholipid, DHPE, these newly identified ligands did not affect RKIP binding to Raf-1 or RKIP phosphorylation. One out of the three ligands displayed off target biological effects, impairing EGF-induced MAPK and metabolic activity. This work defines the binding properties of RKIP ligands under near physiological conditions, establishing RKIP's affinity for hydrophobic ligands and the importance of bulky aliphatic chains for inhibiting its function. The common structural elements of these compounds defines a minimal requirement for RKIP binding and thus they can be used as lead compounds for future design of RKIP ligands with therapeutic potential.

Characterization of the Raf kinase inhibitory protein (RKIP binding pocket: NMR-based screening identifies small-molecule ligands.

Directory of Open Access Journals (Sweden)

Anne N Shemon

2010-05-01

Full Text Available Raf kinase inhibitory protein (RKIP, also known as phoshaptidylethanolamine binding protein (PEBP, has been shown to inhibit Raf and thereby negatively regulate growth factor signaling by the Raf/MAP kinase pathway. RKIP has also been shown to suppress metastasis. We have previously demonstrated that RKIP/Raf interaction is regulated by two mechanisms: phosphorylation of RKIP at Ser-153, and occupation of RKIP's conserved ligand binding domain with a phospholipid (2-dihexanoyl-sn-glycero-3-phosphoethanolamine; DHPE. In addition to phospholipids, other ligands have been reported to bind this domain; however their binding properties remain uncharacterized.In this study, we used high-resolution heteronuclear NMR spectroscopy to screen a chemical library and assay a number of potential RKIP ligands for binding to the protein. Surprisingly, many compounds previously postulated as RKIP ligands showed no detectable binding in near-physiological solution conditions even at millimolar concentrations. In contrast, we found three novel ligands for RKIP that specifically bind to the RKIP pocket. Interestingly, unlike the phospholipid, DHPE, these newly identified ligands did not affect RKIP binding to Raf-1 or RKIP phosphorylation. One out of the three ligands displayed off target biological effects, impairing EGF-induced MAPK and metabolic activity.This work defines the binding properties of RKIP ligands under near physiological conditions, establishing RKIP's affinity for hydrophobic ligands and the importance of bulky aliphatic chains for inhibiting its function. The common structural elements of these compounds defines a minimal requirement for RKIP binding and thus they can be used as lead compounds for future design of RKIP ligands with therapeutic potential.

sup 1 sup 1 B nutation NMR study of powdered borosilicates

CERN Document Server

Woo, A J; Han, D Y

1998-01-01

In this work, we applied the 1D sup 1 sup 1 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO sub 2 -B sub 2 O sub 3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D sup 1 sup 1 B nutation NMR experiment. The sup 1 sup 1 B NMR parameters, quadrupole coupling constants (e sup 2 qQ/h) and asymmetry parameters (eta), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

Application of two-dimensional J-resolved nuclear magnetic resonance spectroscopy to differentiation of beer

International Nuclear Information System (INIS)

Khatib, Alfi; Wilson, Erica G.; Kim, Hye Kyong; Lefeber, Alfons W.M.; Erkelens, Cornelis; Choi, Young Hae; Verpoorte, Robert

2006-01-01

A number of ingredients in beer that directly or indirectly affect its quality require an unbiased wide-spectrum analytical method that allows for the determination of a wide array of compounds for its efficient control. 1 H nuclear magnetic resonance (NMR) spectroscopy is a method that clearly meets this description as the broad range of compounds in beer is detectable. However, the resulting congestion of signals added to the low resolution of 1 H NMR spectra makes the identification of individual components very difficult. Among two-dimensional (2D) NMR techniques that increase the resolution, J-resolved NMR spectra were successfully applied to the analysis of 2-butanol extracts of beer as overlapping signals in 1 H NMR spectra were fully resolved by the additional axis of the coupling constant. Principal component analysis based on the projected J-resolved NMR spectra showed a clear separation between all of the six brands of pilsner beer evaluated in this study. The compounds responsible for the differentiation were identified by 2D NMR spectra including correlated spectroscopy and heteronuclear multiple bond correlation spectra together with J-resolved spectra. They were identified as nucleic acid derivatives (adenine, uridine and xanthine), amino acids (tyrosine and proline), organic acid (succinic and lactic acid), alcohol (tyrosol and isopropanol), cholines and carbohydrates

Anti-ulcerogenic Activity of Extract and Some Isolated Flavonoids from Desmostachia bipinnata (L. Stapf

Directory of Open Access Journals (Sweden)

Amani, S. Awaad

2008-08-01

Full Text Available Five main flavonoid glycosides were isolated, for the first time, from the ethanol extract of Desmostachia bipinnata (L.Stapf ( Gramineae . They were identified as kaempferol(1, quercetin(2, quercetin-3-glucoside(3, trycin(4 and trycin-7-glucoside(5. The structure elucidation was based on UV, Electrospray ionization mass spectrometry (ESIMS, 1H and 13C NMR, proton- proton correlation spectroscopy ( 1H- 1H Cosy, distortionless enhancement by polarization transfer (DEPT, heteronuclear single quantum coherence (HSQC, and heteronuclear multiple bond correlations spectrum (HMBC. The total extract (200 and 300 mg/kg and two of the isolated compounds (trycin and trycin-7-glucoside.100 mg/kg each showed a very promising antiulcerogenic activity with curative ratios; 68.31, 70.54, 77.39 and 78.93%, respectively.

A primer to nutritional metabolomics by NMR spectroscopy and chemometrics

DEFF Research Database (Denmark)

Savorani, Francesco; Rasmussen, Morten Arendt; Mikkelsen, Mette Skau

2013-01-01

This paper outlines the advantages and disadvantages of using high throughput NMR metabolomics for nutritional studies with emphasis on the workflow and data analytical methods for generation of new knowledge. The paper describes one-by-one the major research activities in the interdisciplinary...... metabolomics platform and highlights the opportunities that NMR spectra can provide in future nutrition studies. Three areas are emphasized: (1) NMR as an unbiased and non-destructive platform for providing an overview of the metabolome under investigation, (2) NMR for providing versatile information and data...... structures for multivariate pattern recognition methods and (3) NMR for providing a unique fingerprint of the lipoprotein status of the subject. For the first time in history, by combining NMR spectroscopy and chemometrics we are able to perform inductive nutritional research as a complement to the deductive...

Isolation and identification of flavonoids, including flavone rotamers, from the herbal drug 'Crataegi folium cum flore' (hawthorn).

Science.gov (United States)

Rayyan, S; Fossen, T; Solheim Nateland, H; Andersen, O M

2005-01-01

Twelve flavonoids, including seven flavones, four flavonols and one flavanone, were isolated from methanolic extract of the herbal drug 'Crataegi folium cum flore' (hawthorn leaves and flowers) by a combination of CC (over Amberlite XAD-7 and Sephadex LH-20) and preparative HPLC. Their structures, including that of the novel flavonol 8-methoxykaempferol 3-O-(6"-malonyl-beta-glucopyranoside), were elucidated by homo- and heteronuclear NMR and electrospray/MS. The 1H- and 13C-NMR of all compounds, including rotameric pairs of five flavone C-glycosides, were assigned. The presence and relative proportion of each rotamer was shown by various NMR experiments, including two-dimensional nuclear Overhauser and exchange spectroscopy, to depend on solvent, linkage position and structure of the C-glycosyl substituent.

Flow units from integrated WFT and NMR data

Energy Technology Data Exchange (ETDEWEB)

Kasap, E.; Altunbay, M.; Georgi, D.

1997-08-01

Reliable and continuous permeability profiles are vital as both hard and soft data required for delineating reservoir architecture. They can improve the vertical resolution of seismic data, well-to-well stratigraphic correlations, and kriging between the well locations. In conditional simulations, permeability profiles are imposed as the conditioning data. Variograms, covariance functions and other geostatistical indicators are more reliable when based on good quality permeability data. Nuclear Magnetic Resonance (NMR) logging and Wireline Formation Tests (WFT) separately generate a wealth of information, and their synthesis extends the value of this information further by providing continuous and accurate permeability profiles without increasing the cost. NMR and WFT data present a unique combination because WFTs provide discrete, in situ permeability based on fluid-flow, whilst NMR responds to the fluids in the pore space and yields effective porosity, pore-size distribution, bound and moveable fluid saturations, and permeability. The NMR permeability is derived from the T{sub 2}-distribution data. Several equations have been proposed to transform T{sub 2} data to permeability. Regardless of the transform model used, the NMR-derived permeabilities depend on interpretation parameters that may be rock specific. The objective of this study is to integrate WFT permeabilities with NMR-derived, T{sub 2} distribution-based permeabilities and thereby arrive at core quality, continuously measured permeability profiles. We outlined the procedures to integrate NMR and WFT data and applied the procedure to a field case. Finally, this study advocates the use of hydraulic unit concepts to extend the WFT-NMR derived, core quality permeabilities to uncored intervals or uncored wells.

NMR structural studies of oligosaccharides and other natural products

DEFF Research Database (Denmark)

Kjærulff, Louise

produce secondary metabolites for signaling and competing against other organisms, and these molecules are important in drug discovery due to their inherent biological activities. From a marine Photobacterium (P. halotolerans) we isolated the solonamides and the ngercheumicins, two families of cyclic...... through the nJCH correlation, this experiment has exciting applications for configurational assignment of e.g. carbohydrates and for residual dipolar couplings. Identification of known molecules and discovery of novel molecules are other important applications of NMR spectroscopy. Bacteria and fungi....... fijiensis, was also investigated for production of novel secondary metabolites, and a new pyranonigrin (E) was isolated and structure elucidated by NMR spectroscopy along with JBIR-74 and decumbenone A, two known metabolites previously isolated from Aspergillus and Penicillium species. Oligosaccharides...

HPLC-NMR revisited: Using time-slice HPLC-SPE-NMR with database assisted dereplication

DEFF Research Database (Denmark)

Johansen, Kenneth; Wubshet, Sileshi Gizachew; Nyberg, Nils

2013-01-01

Time based trapping of chromatographically separated compounds on to solid-phase extraction cartridges (SPE) and subsequent elution to NMR-tubes was done to emulate the function of HPLC–NMR for dereplication purposes. Sufficient mass sensitivity was obtained by the use of a state-of-the-art HPLC......–SPE–NMR-system with a cryogenically cooled probe head, designed for 1.7 mm NMR-tubes. The resulting 1H NMR spectra (600 MHz) were evaluated against a database of previously acquired and prepared spectra. The in-house developed matching algorithm, based on partitioning of the spectra and allowing for changes in the chemical shifts......, is described and the code included as Supplementary Information. Two mixtures of natural products was used to test the approach; one extract of Carthamus oxyacantha (wild safflower) containing an array of spiro compounds and one extract of the endophytic fungus Penicillum namyslowski containing griseofulvin...

NMR for chemists and biologists

CERN Document Server

Carbajo, Rodrigo J

2013-01-01

This book offers a concise introduction to the field of nuclear magnetic resonance or NMR. It presents the basic foundations of NMR in a non-mathematical way and provides an overview of both recent and important biological applications of NMR.

2D NMR studies on muscle and cerebral metabolism in vivo

Energy Technology Data Exchange (ETDEWEB)

Gillet, B.; Doan, B.T.; Verre-Sebrie, C.; Fedeli, O.; Beloeil, J.C. (Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France). Inst. de Chimie des Substances Naturelles); Peres, M. (CERMA-CEV, 91 - Bretigny-sur-Orge (France)); Barrere, B.; Seylaz, J. (Paris-7 Univ., 75 (France)); Morin, S.; Koenig, J. (Bordeaux-1 Univ., 33 - Talence (France)); Sebille, A. (Faculte de Medecine Saint-Antoine, 75 - Paris (France))

1994-06-01

New developments in in vivo 2D[sup 1]H NMR spectroscopy now allow several metabolites, which are not resolved by 1D NMR to be assigned. This report describes the use of this technique to follow the time courses of changes in the concentration of metabolites in the rat brain during physiological and pathophysiological processes (hyperglycemia and hypoxia) and to compare the fatty acid components of normal and dystrophic mouse gastrocnemius muscle. (authors). 15 refs., 5 figs.

31P-NMR studies on perfused mouse liver

International Nuclear Information System (INIS)

McLaughlin, A.C.; Takeda, H.; Chance, B.

1978-01-01

From a metabolic viewpoint, the most important organ in the body is the liver. In contrast to more specialized organs such as heart and kidney which perform only one major function, the liver performs a number of major metabolic functions. Two of the most important functions are the catabolism and storage of foodstuffs (in the form of glycogen) and the control of most of the constituents of the blood (in particular, the blood glucose level). Most of these functions are localized within a single type of cell. One way that the liver is able to regulate these diverse reactions is by the control of the ATP level in the cell. Encouraged by the recent success of many groups in using 31 P-NMR to provide a continuous and non-destructive monitor of ATP levels in isolated cells, skeletal muscle, and perfused organs such as heart and kidney, 31 P-NMR was used to investigate ATP levels in perfused liver of mice

Compact NMR

Energy Technology Data Exchange (ETDEWEB)

Bluemich, Bernhard; Haber-Pohlmeier, Sabina; Zia, Wasif [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMC)

2014-06-01

Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

Application of 31P-NMR spectroscopy to the study of striated muscle metabolism

International Nuclear Information System (INIS)

Meyer, R.A.; Kushmerick, M.J.; Brown, T.R.

1982-01-01

This review presents the principles and limitations of phosphorus nuclear magnetic resonance ( 31 P-NMR) spectroscopy as applied to the study of striated muscle metabolism. Application of the techniques discussed include noninvasive measurement of high-energy phosphate, intracellular pH, intracellular free Mg 2+ , and metabolite compartmentation. In perfused cat biceps (fast-twitch) muscles, but not in soleus (slow-twitch), NMR spectra indicate a substantially lower (1 mM) free inorganic phosphate level than when measured chemically (6 mM). In addition, saturation and inversion spin-transfer methods that enable direct measurement of the unidirectional fluxes through creatine kinase are described. In perfused cat biceps muscle, results suggest that this enzyme and its substrates are in simple chemical equilibrium

Xenon NMR of liquid crystals confined to cylindrical nanocavities: a simulation study.

Science.gov (United States)

Karjalainen, Jouni; Vaara, Juha; Straka, Michal; Lantto, Perttu

2015-03-21

independent of temperature. Our results show that the combination of CG simulations and a QC pre-parameterised (129)Xe NMR shielding allows efficient studies of the phase behaviour and structure of complex systems containing thousands of molecules, and brings us closer to the simulation of NMR experiments.

Sepsis does not alter red blood cell glucose metabolism or Na+ concentration: A 2H-, 23Na-NMR study

International Nuclear Information System (INIS)

Hotchkiss, R.S.; Song, S.K.; Ling, C.S.; Ackerman, J.J.; Karl, I.E.

1990-01-01

The effects of sepsis on intracellular Na+ concentration ([Na+]i) and glucose metabolism were examined in rat red blood cells (RBCs) by using 23Na- and 2H-nuclear magnetic resonance (NMR) spectroscopy. Sepsis was induced in 15 halothane-anesthetized female Sprague-Dawley rats by using the cecal ligation and perforation technique; 14 control rats underwent cecal manipulation without ligation. The animals were fasted for 36 h, but allowed free access to water. At 36 h postsurgery, RBCs were examined by 23Na-NMR by using dysprosium tripolyphosphate as a chemical shift reagent. Human RBCs from 17 critically ill nonseptic patients and from 7 patients who were diagnosed as septic were also examined for [Na+]i. Five rat RBC specimens had [Na+]i determined by both 23Na-NMR and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). For glucose metabolism studies, RBCs from septic and control rats were suspended in modified Krebs-Henseleit buffer containing [6,6-2H2]glucose and examined by 2H-NMR. No significant differences in [Na+]i or glucose utilization were found in RBCs from control or septic rats. There were no differences in [Na+]i in the two groups of patients. The [Na+]i determined by NMR spectroscopy agreed closely with measurements using ICP-AES and establish that 100% of the [Na+]i of the RBC is visible by NMR. Glucose measurements determined by 2H-NMR correlated closely (correlation coefficient = 0.93) with enzymatic analysis. These studies showed no evidence that sepsis disturbed RBC membrane function or metabolism

Deuterium NMR, induced and intrinsic cholesteric lyomesophases

International Nuclear Information System (INIS)

Alcantara, M.R.

1982-01-01

Induced and intrinsic cholesteric lyotropic mesophases were studied. Induced cholesteric lyomesophases based on potassium laurate (KL) system, with small amounts of cholesterol added, were studied by deuterium NMR and by polarizing microscopy. Order profiles obtained from deuterium NMR of KL perdenderated chains in both induced cholesteric and normal mesophases were compared. The intrinsic cholesteric lyotropic mesophases were based on the amphiphile potassium N-lauroyl serinate (KLNS) in the resolved levo form. The study of the type I intrinsic cholesteric mesophase was made by optical microscopy under polarized light and the type II intrinsic cholesteric lyomesophase was characterized by deuterium NMR. The new texture was explained by the use of the theory of disclinations developed for thermotropic liquid crystals, specially for cholesteric type. (M.J.C.) [pt

Structural characterization of Kraft lignins from different spent cooking liquors by 1D and 2D Nuclear Magnetic Resonance spectroscopy

International Nuclear Information System (INIS)

Fernández-Costas, C.; Gouveia, S.; Sanromán, M.A.; Moldes, D.

2014-01-01

Three Kraft lignins isolated from black liquors of several paper pulp mills of the North of Spain and Portugal were structurally characterized by using monodimensional ( 1 H and 13 C) and bidimensional Nuclear Magnetic Resonance (NMR) spectrometry. From the latter, 13 C– 1 H heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) were employed. Lignins from black liquors are usually burned for power generation. Nevertheless, they could become high value added products within a biorefinery context. In that case, a good understanding of their structure is a prior step to transform them. From all the NMR techniques studied, HSQC has risen as the most powerful tool in lignin characterization. Kraft cooking conditions and the type of wood seem to be the main factors that determine the differences observed in the lignins. All the samples have shown an important decrease in the number of β–O–4′ linkages, due to the Kraft process, and resinol has become the most resistant linkage to the process. Moreover, all samples seem to be mainly linked to a one polysaccharide: xylan. Several parameters like S/G ratio, portion of phenolic and aliphatic hydroxyls, amount of aromatic protons and other structural aspects were also estimated. - Highlights: • Lignins from three Kraft spent liquors were obtained by acid precipitation. • Structural characterization of the dissolved lignins was performed by NMR. • Wood source and pulping conditions determine the lignin characteristics. • Kraft process implies cleavage of β–O–4 linkages and survival of resinol linkages. • Comparison of the samples would aid decisions on its future revalorization

Study on 1H-NMR fingerprinting of Rhodiolae Crenulatae Radix et Rhizoma.

Science.gov (United States)

Wen, Shi-yuan; Zhou, Jiang-tao; Chen, Yan-yan; Ding, Li-qin; Jiang, Miao-miao

2015-07-01

Nuclear magnetic resonance (1H-NMR) fingerprint of Rhodiola rosea medicinal materials was established, and used to distinguish the quality of raw materials from different sources. Pulse sequence for water peak inhibition was employed to acquire 1H-NMR spectra with the temperature at 298 K and spectrometer frequency of 400.13 MHz. Through subsection integral method, the obtained NMR data was subjected to similarity analysis and principal component analysis (PCA). 10 batches raw materials of Rhodiola rosea from different origins were successfully distinguished by PCA. The statistical results indicated that rhodiola glucoside, butyl alcohol, maleic acid and alanine were the main differential ingredients. This method provides an auxiliary method of Chinese quality approach to evaluate the quality of Rhodiola crenulata without using natural reference substances.

NMR study of hydride systems

International Nuclear Information System (INIS)

Peretz, M.

1980-02-01

The hydrides of thorium (ThH 2 , Th 4 H 15 and Th 4 D 15 ) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x)) 2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th 4 H 15 than in ThH 2 ; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th 4 H 15 ; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

NMR with generalized dynamics of spin and spatial coordinates

International Nuclear Information System (INIS)

Lee, Chang Jae.

1987-11-01

This work is concerned with theoretical and experimental aspects of the generalized dynamics of nuclear spin and spatial coordinates under magnetic-field pulses and mechanical motions. The main text begins with an introduction to the concept of ''fictitious'' interactions. A systematic method for constructing fictitious spin-1/2 operators is given. The interaction of spins with a quantized-field is described. The concept of the fictitious interactions under the irradiation of multiple pulses is utilized to design sequences for selectively averaging linear and bilinear operators. Relations between the low-field sequences and high-field iterative schemes are clarified. These relations and the transformation properties of the spin operators are exploited to develop schemes for heteronuclear decoupling of multi-level systems. The resulting schemes are evaluated for heteronuclear decoupling of a dilute spin-1/2 from a spin-1 in liquid crystal samples and from a homonuclear spin-1/2 pair in liquids. A relation between the spin and the spatial variables is discussed. The transformation properties of the spin operators are applied to spatial coordinates and utilized to develop methods for removing the orientational dependence responsible for line broadening in a powder sample. Elimination of the second order quadrupole effects, as well as the first order anisotropies is discussed. It is shown that various sources of line broadening can effectively be eliminated by spinning and/or hopping the sample about judiciously chosen axes along with appropriate radio-frequency pulse sequences

Hyperpolarized NMR Probes for Biological Assays

Directory of Open Access Journals (Sweden)

Sebastian Meier

2014-01-01

Full Text Available During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments.

Bayesian Peak Picking for NMR Spectra

KAUST Repository

Cheng, Yichen

2014-02-01

Protein structure determination is a very important topic in structural genomics, which helps people to understand varieties of biological functions such as protein-protein interactions, protein–DNA interactions and so on. Nowadays, nuclear magnetic resonance (NMR) has often been used to determine the three-dimensional structures of protein in vivo. This study aims to automate the peak picking step, the most important and tricky step in NMR structure determination. We propose to model the NMR spectrum by a mixture of bivariate Gaussian densities and use the stochastic approximation Monte Carlo algorithm as the computational tool to solve the problem. Under the Bayesian framework, the peak picking problem is casted as a variable selection problem. The proposed method can automatically distinguish true peaks from false ones without preprocessing the data. To the best of our knowledge, this is the first effort in the literature that tackles the peak picking problem for NMR spectrum data using Bayesian method.

O-17 NMR measurement of water

International Nuclear Information System (INIS)

Fukazawa, Nobuyuki

1990-01-01

Recently, attention has been paid to the various treatment of water and the utilization of water by magnetic treatment, electric field treatment and so on. It has been said that by these treatments, the change in the properties of water arises. The state of this treated water cannot be explained by the properties of water from conventional physical and chemical standpoints. In addition, the method of measurement of whether the change arose or not is not yet determined. It is necessary to establish the method of measurement for the basic state of water. In this study, O-17 NMR which observes the state of water directly at molecular or atomic level was investigated as the method of measuring water. The measurement of O-17 NMR was carried out with a JNR 90Q FT NMR of Fourier transformation type of JEOL Ltd. The experimental method and the results are reported. The result of measurement of the O-17 NMR spectrum for distilled ion exchange water is shown. It is know that it has very wide line width as compared with the NMR spectra of protons and C-13. The relative sensitivity of O-17 observation is about 1/100,000 of that of protons. As to the information on the state of water obtained by O-17 NMR, there are chemical shift and line width. As temperature rose, the line width showed decrease, which seemed to be related to the decrease of hydrogen combination. (K.I.)

Quantification of aluminium-27 NMR spectra of high-surface-area oxides

International Nuclear Information System (INIS)

Pearson, R.M.; Schramm, C.M.

1990-01-01

This paper discusses the quantitation of 27 Al NMR spectra. It is showns that the so called 'invisible' aluminium atoms seen by recent workers are completely consistent with known continuous wave NMR studies of the 27 Al NMR spectra of high surface area aluminium oxides. The use of pulsed NMR techniques further complicate the quantitative measurement of 27 Al NMR spectra, especially when high resolution NMR spectrometers are used for this purpose. Methods are described which allow both the estimation of aluminium not seen by continuous wave techniques and the amounts of the NMR spectra lost in pulsed work. (author). 24 refs.; 6 figs.; 1 tab

NMR analysis of male fathead minnow urinary metabolites: A potential approach for studying impacts of chemical exposures

Energy Technology Data Exchange (ETDEWEB)

Ekman, D.R. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)], E-mail: ekman.drew@epa.gov; Teng, Q. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States); Jensen, K.M.; Martinovic, D.; Villeneuve, D.L.; Ankley, G.T. [Mid-Continent Ecology Division, U.S. EPA, 6201 Congdon Boulevard, Duluth, MN 55804 (United States); Collette, T.W. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)

2007-11-30

The potential for profiling metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy was used for the assignment of metabolites in urine from unexposed fish. Because fathead minnow urine is dilute, we lyophilized these samples prior to analysis. Furthermore, 1D {sup 1}H NMR spectra of unlyophilized urine from unexposed male fathead minnow and Sprague-Dawley rat were acquired to qualitatively compare rat and fish metabolite profiles and to provide an estimate of the total urinary metabolite pool concentration difference. As a small proof-of-concept study, lyophilized urine samples from male fathead minnows exposed to three different concentrations of the antiandrogen vinclozolin were analyzed by 1D {sup 1}H NMR to assess exposure-induced changes. Through a combination of principal components analysis (PCA) and measurements of {sup 1}H NMR peak intensities, several metabolites were identified as changing with statistical significance in response to exposure. Among those changes occurring in response to exposure to the highest concentration (450 {mu}g/L) of vinclozolin were large increases in taurine, lactate, acetate, and formate. These increases coincided with a marked decrease in hippurate, a combination potentially indicative of hepatotoxicity. The results of these investigations clearly demonstrate the potential utility of an NMR-based approach for assessing chemical exposures in male fathead minnow, using urine collected from individual fish.

NMR analysis of male fathead minnow urinary metabolites: A potential approach for studying impacts of chemical exposures

International Nuclear Information System (INIS)

Ekman, D.R.; Teng, Q.; Jensen, K.M.; Martinovic, D.; Villeneuve, D.L.; Ankley, G.T.; Collette, T.W.

2007-01-01

The potential for profiling metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy was used for the assignment of metabolites in urine from unexposed fish. Because fathead minnow urine is dilute, we lyophilized these samples prior to analysis. Furthermore, 1D 1 H NMR spectra of unlyophilized urine from unexposed male fathead minnow and Sprague-Dawley rat were acquired to qualitatively compare rat and fish metabolite profiles and to provide an estimate of the total urinary metabolite pool concentration difference. As a small proof-of-concept study, lyophilized urine samples from male fathead minnows exposed to three different concentrations of the antiandrogen vinclozolin were analyzed by 1D 1 H NMR to assess exposure-induced changes. Through a combination of principal components analysis (PCA) and measurements of 1 H NMR peak intensities, several metabolites were identified as changing with statistical significance in response to exposure. Among those changes occurring in response to exposure to the highest concentration (450 μg/L) of vinclozolin were large increases in taurine, lactate, acetate, and formate. These increases coincided with a marked decrease in hippurate, a combination potentially indicative of hepatotoxicity. The results of these investigations clearly demonstrate the potential utility of an NMR-based approach for assessing chemical exposures in male fathead minnow, using urine collected from individual fish

Structural Biology: Practical NMR Applications

CERN Document Server

Teng, Quincy

2005-01-01

This textbook begins with an overview of NMR development and applications in biological systems. It describes recent developments in instrument hardware and methodology. Chapters highlight the scope and limitation of NMR methods. While detailed math and quantum mechanics dealing with NMR theory have been addressed in several well-known NMR volumes, chapter two of this volume illustrates the fundamental principles and concepts of NMR spectroscopy in a more descriptive manner. Topics such as instrument setup, data acquisition, and data processing using a variety of offline software are discussed. Chapters further discuss several routine stategies for preparing samples, especially for macromolecules and complexes. The target market for such a volume includes researchers in the field of biochemistry, chemistry, structural biology and biophysics.

NMR and domain wall mobility in intermetallic compounds

International Nuclear Information System (INIS)

Guimaraes, A.P.; Sampaio, L.C.; Cunha, S.F.; Alves, K.M.B.

1991-01-01

The technique of pulsed NMR can be used to study the distribution of hyperfine fields in a magnetic matrix. The dynamics of the domain walls are relevant to the generation of NMR signals. In the present study on the (R x Y 1-x ) Fe 2 intermetallic compounds, the reduction in the signals is associated to increased propagation fields. This indicates that a smaller domain wall mobility is at the origin of these effects. NMR spectra in this system show the importance of direct and indirect (i.e., mediated by Fe atoms) terms in the transferred hyperfine field. (author)

In vivo 7Li and 19F NMR studies of drugs in the brain

International Nuclear Information System (INIS)

Komoroski, Richard A.

1999-01-01

For various reasons, it is advantageous to measure the concentration of a psychoactive drug in the brain in vivo. Many drugs contain the element fluorine. Using 19 F NMR spectroscopy, we have studied the psychoactive drugs trifluoperazine and fluoxetine in the brain in vivo. Using 7 Li NMR, it is possible to detect lithium ion, used to treat manic depressive illness. We have measured the concentration and distribution of lithium in both human and rat brain in vivo. Measurement of drug levels in the human brain may provide a measure of therapeutic or toxic effects, as well as insight into drug metabolism and mechanism of action. (author)

NMR study of damage on isolated perfused rat heart exposed to ischemia and hypoxia

International Nuclear Information System (INIS)

Luo Xuechun; Yan Yongbin; Zhang Riqing; Fan Lili

2001-01-01

Myocardial ischemia is the most common and primary cause of myocardium damage. Numerous conventional techniques and methods have been developed for ischemia and reperfusion studies. However, because of damage to the heart sample, most of these techniques can not be used to continuously monitor the full dynamic course of the myocardial metabolic pathway. The nuclear magnetic resonance (NMR) surface coil technique, which overcomes the limitations of conventional instrumentation, can be used to quantitatively study every stage of the perfused heart (especially after perfusion stoppage) continuously, dynamically, and without damage under normal or designed physiological conditions at the molecular level. In this paper, 31 P-NMR was used to study the effects of ischemia and hypoxia on isolated perfused hearts. The results show that complete hypoxia caused more severe functional damage to the myocardial cells than complete ischemia

Metabolic studies with NMR spectroscopy of the alga Dunaliella salina trapped within agarose beads.

Science.gov (United States)

Bental, M; Pick, U; Avron, M; Degani, H

1990-02-22

A technique for the entrapment of the unicellular algae Dunaliella salina in agarose beads and their perfusion during NMR measurements is presented. The trapped cells maintained their ability to proliferate under normal growth conditions, and remained viable and stable under steady-state conditions for long periods during NMR measurements. Following osmotic shock in the dark, prominent changes were observed in the intracellular level of ATP and polyphosphates, but little to no changes in the intracellular pH or orthoposphate content. When cells were subjected to hyperosmotic shock, the ATP level decreased. The content of NMR-visible polyphosphates decreased as well, presumably due to the production of longer, NMR-invisible structures. Following hypoosmotic shock, the ATP content increased and longer polyphosphates were broken down to shorter, more mobile polymers.

A 55Mn NMR study of the La0.75Sr0.25MnO3 nanoparticles

International Nuclear Information System (INIS)

Rybicki, D.; Sikora, M.; Kapusta, Cz.; Riedi, P.C.; Jirak, Z.; Knizek, K.; Marysko, M.; Pollert, E.; Veverka, P.

2006-01-01

We report on a 55 Mn NMR study of the La 0.75 Sr 0.25 MnO 3 nanoparticles of the average grain size 33 nm and 114 nm at 4.2 K and 77 K and at applied field of 0, 0.2 and 0.5T. A dominant signal from the double exchange (DE) controlled metallic ferromagnetic interior of the grains as well as a small signal from insulating ferromagnetic regions is observed. From a comparison with bulk magnetization measurement the thickness of the nonferromagnetic outer layer of the grains and the amount of the ferromagnetic insulating phase was determined. The relative amount of these phases with respect to the ferromagnetic metallic phase increases with decreasing grain size. The DE line in the NMR spectrum shows a frequency shift with applied field according to a full 55 Mn gyromagnetic ratio. A value of the demagnetizing field close to zero is obtained, which indicates a single domain state of the nanoparticles. For the sample with larger grains a higher NMR enhancement is observed, which indicates a higher magnetic susceptibility of the sample at the NMR frequencies. A comparison with the NMR data obtained on a microcrystalline material is made. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

NMR study of the 1-13C glucose colon bacterial metabolism

International Nuclear Information System (INIS)

Briet, F.; Flourie, B.; Pochart, P.; Rambaud, J.C.; Desjeux, J.F.; Dallery, L.; Grivet, J.P.

1994-01-01

The aim of the study is to examine in-vitro and by nuclear magnetic resonance the biological pathways for the fermentation of the 1- 13 C labelled glucose (99 atoms percent) by human colon bacteria. The preparation of the bacterial suspension and the glucose degradation kinetics are presented; the NMR analysis sensitivity and quantification features are discussed and results are presented. 2 figs., 1 ref

Intracellular pH and inorganic phosphate content of heart in vivo: A 31P-NMR study

International Nuclear Information System (INIS)

Katz, L.A.; Swain, J.A.; Portman, M.A.; Balaban, R.S.

1988-01-01

Studies were performed to determine the contribution of red blood cells to the 31 P-nuclear magnetic resonance (NMR) spectrum of the canine heart in vivo and the feasibility of measuring myocardial intracellular phosphate and pH. This was accomplished by replacing whole blood with a perfluorochemical perfusion emulsion blood substitute, Oxypherol, and noting the difference in the 31 P-NMR spectrum of the heart. NMR data were collected with a NMR transmitter-receiver coil on the surface of the distal portion of the left ventricle. These studies demonstrated that a small contribution from 2,3-diphosphoglycerate (2,3-DPG) and phosphodiesters in the blood could be detected. The magnitude and shift of these blood-borne signals permitted the relative quantification of intracellular inorganic phosphate (P i ) content as well as intracellular pH. Under resting conditions, the intracellular ATP/P i was 7.0 ± 0.08. This corresponds to a free intracellular P 1 content of ∼ 0.8 μmol./g wet wt. The intracellular pH was 7.10 ± 0.01. Acute respiratory alkalosis and acidosis, with the arterial pH ranging from ∼7.0 to 7.7, resulted in only small changes in the intracellular pH. These latter results demonstrate an effective myocardial intracellular proton-buffering mechanism in vivo

An in-cell NMR study of monitoring stress-induced increase of cytosolic Ca{sup 2+} concentration in HeLa cells

Energy Technology Data Exchange (ETDEWEB)

Hembram, Dambarudhar Shiba Sankar; Haremaki, Takahiro; Hamatsu, Jumpei; Inoue, Jin; Kamoshida, Hajime; Ikeya, Teppei; Mishima, Masaki [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan); Mikawa, Tsutomu [Cellular and Molecular Biology Unit, RIKEN Advanced Science Institute, Wako-shi, Saitama 351-0198 (Japan); Hayashi, Nobuhiro [Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 B-1, Nagatsuda-chou, Midori-ku, Yokohama, Kanagawa 226-8501 (Japan); Shirakawa, Masahiro [Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Ito, Yutaka, E-mail: ito-yutaka@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan)

2013-09-06

Highlights: •We performed time-resolved NMR observations of calbindin D{sub 9k} in HeLa cells. •Stress-induced increase of cytosolic Ca{sup 2+} concentration was observed by in-cell NMR. •Calbindin D{sub 9k} showed the state-transition from Mg{sup 2+}- to Ca{sup 2+}-bound state in cells. •We provide a useful tool for in situ monitoring of the healthiness of the cells. -- Abstract: Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. The lifetime of in-cell NMR samples is however much shorter than that in culture media, presumably because of various stresses as well as the nutrient depletion in the anaerobic environment within the NMR tube. It is well known that Ca{sup 2+}-bursts occur in HeLa cells under various stresses, hence the cytosolic Ca{sup 2+} concentration can be regarded as a good indicator of the healthiness of cells in NMR tubes. In this study, aiming at monitoring the states of proteins resulting from the change of cytosolic Ca{sup 2+} concentration during experiments, human calbindin D{sub 9k} (P47M + C80) was used as the model protein and cultured HeLa cells as host cells. Time-resolved measurements of 2D {sup 1}H–{sup 15}N SOFAST–HMQC experiments of calbindin D{sub 9k} (P47M + C80) in HeLa cells showed time-dependent changes in the cross-peak patterns in the spectra. Comparison with in vitro assignments revealed that calbindin D{sub 9k} (P47M + C80) is initially in the Mg{sup 2+}-bound state, and then gradually converted to the Ca{sup 2+}-bound state. This conversion process initiates after NMR sample preparation. These results showed, for the first time, that cells inside the NMR tube were stressed, presumably because of cell precipitation, the lack of oxygen and nutrients, etc., thereby releasing Ca{sup 2+} into cytosol during the measurements. The results demonstrated that in-cell NMR can monitor the state transitions of stimulated cells through the observation of

Investigation of zeolites by solid state quadrapole NMR

International Nuclear Information System (INIS)

Janssen, R.

1990-01-01

The subject of this thesis is the NMR investigation of zeolites. The nature and properties of zeolites are discussed. Some of the basic priniples of NMR techniques on quadrupole nuclei are presented. A special technique, namely a two-dimensional nutation experiment is discussed in detail. The theory of the nutation experiment for quadrupole spin species with spin quantum number 3/2 as well as 5/2 is presented. For both spin spcies the theoretical spectra are compared with experimental results. It is also shown that the nutation expeirment can be performed with several pulse schemes. It is shown how phase-sensitive pure-absorption nutation spectra can be obtained and an NMR-probe is presented that is capable of performing NMR experiments at high (up to 500 degree C) temperatures. The two-dimensional nutation NMR technique has been applied to sodium cations in zeolite NaA. For this purpose a numbre of zeolite samples were prepared that contained different amounts of water. With the aid of nutation NMR the hydration of the zeolite can be studied and conclusions can be drawn about the symmetry of the surrounding of the sodium cations. With the aid of an extension of the nutation NMR experiment: Rotary Echo Nutation NMR, it is shown that in zeolite NaA, in various stages of hydration, the sodium cations or water molecules are mobile. Proof is given by means of high-temperature 23 Na-NMR that dehydrates zeolite NaA undergoes a phase transition at ca. 120 degree C. In a high-temperature NMR investigation of zeolite ZSM-5 it is shown that the sodium ions start to execute motions when the temperature is increased. (author). 198 refs.; 72 figs.; 6 tabs

Study of acute biochemical effects of thallium toxicity in mouse urine by NMR spectroscopy.

Science.gov (United States)

Tyagi, Ritu; Rana, Poonam; Khan, Ahmad Raza; Bhatnagar, Deepak; Devi, M Memita; Chaturvedi, Shubhra; Tripathi, Rajendra P; Khushu, Subash

2011-10-01

Thallium (Tl) is a toxic heavy metal and its exposure to the human body causes physiological and biochemical changes due to its interference with potassium-dependent biological reactions. A high-resolution (1)H NMR spectroscopy based metabonomic approach has been applied for investigating acute biochemical effects caused by thallium sulfate (Tl(2)SO(4)). Male strain A mice were divided in three groups and received three doses of Tl(2)SO(4) (5, 10 and 20 mg kg(-1) b.w., i.p.). Urine samples collected at 3, 24, 72 and 96 h post-dose time points were analyzed by (1)H NMR spectroscopy. NMR spectral data were processed and analyzed using principal components analysis to represent biochemical variations induced by Tl(2)SO(4). Results showed Tl-exposed mice urine to have distinct metabonomic phenotypes and revealed dose- and time-dependent clustering of treated groups. The metabolic signature of urine analysis from Tl(2)SO(4)-treated animals exhibited an increase in the levels of creatinine, taurine, hippurate and β-hydroxybutyrate along with a decrease in energy metabolites trimethylamine and choline. These findings revealed Tl-induced disturbed gut flora, membrane metabolite, energy and protein metabolism, representing physiological dysfunction of vital organs. The present study indicates the great potential of NMR-based metabonomics in mapping metabolic response for toxicology, which could ultimately lead to identification of potential markers for Tl toxicity. Copyright © 2011 John Wiley & Sons, Ltd.

MAS NMR of HIV-1 protein assemblies

Science.gov (United States)

Suiter, Christopher L.; Quinn, Caitlin M.; Lu, Manman; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana

2015-04-01

The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates.

NMR study of CeTe at low temperatures

Energy Technology Data Exchange (ETDEWEB)

Hinderer, J. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)]. E-mail: hinderer@phys.ethz.ch; Weyeneth, S.M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Weller, M. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Gavilano, J.L. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Felder, E. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Hulliger, F. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland); Ott, H.R. [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zurich (Switzerland)

2006-05-01

We present {sup 125}Te NMR measurements on CeTe powder at temperatures between 1 and 150K and in magnetic fields between 5 and 8T. CeTe is a rocksalt-type intermetallic compound. It orders antiferromagnetically at T{sub N}{approx}2.2K with a much reduced ordered moment [H.R. Ott, J.K. Kjems, F. Hulliger, Phys. Rev. Lett. 42 20 (1979) 1378]. From our low-temperature NMR spectra we infer the presence of at least three inequivalent Te sites at low temperatures. Considering the crystal structure this result is completely unexpected. The linewidths and the Knight shifts of the individual lines are significantly different and increase substantially with decreasing temperature. They follow the temperature dependence of the magnetic susceptibility above 20K. Above T{sub N}, hyperfine fields of 1.6, 0.8 and 0.0T at the three Te sites per Bohr magneton of Ce moment are deduced from Knight shift vs. magnetic susceptibility data. These values are typical for transferred hyperfine fields via conduction electrons.

Nuclear Magnetic Resonance (NMR Study for the Detection and Quantitation of Cholesterol in HSV529 Therapeutic Vaccine Candidate

Directory of Open Access Journals (Sweden)

Rahima Khatun

Full Text Available This study describes the NMR-based method to determine the limit of quantitation (LOQ and limit of detection (LOD of cholesterol, a process-related impurity in the replication-deficient Herpes Simplex Virus (HSV type 2 candidate vaccine HSV529. Three signature peaks from the 1D 1H NMR of a cholesterol reference spectrum were selected for the identification of cholesterol. The LOQ for a cholesterol working standard was found to be 1 μg/mL, and the LOD was found to be 0.1 μg/mL. The identity of cholesterol, separated from the formulation of growth supplement by thin layer chromatography (TLC, was confirmed by 1D 1H NMR and 2D 1H-13C HSQC NMR. The three signature peaks of cholesterol were detected only in a six-times concentrated sample of HSV529 candidate vaccine sample and not in the single dose HSV529 vaccine sample under similar experimental conditions. Taken together, the results demonstrated that NMR is a direct method that can successfully identify and quantify cholesterol in viral vaccine samples, such as HSV529, and as well as in the growth supplement used during the upstream stages of HSV529 manufacturing. Keywords: Herpes simplex virus type 2 (HSV-2, Viral vaccine, NMR, Residuals, LOD and LOQ, TLC, Growth supplement

Muscular pathology: echographic and NMR imaging aspects

International Nuclear Information System (INIS)

Pascal-Suisse, P.; Beaurain, P.; Mougniot, C.

1995-01-01

A comparison of echographic techniques and NMR imaging has been done for the diagnosis of muscular trauma and tumor pathologies. In traumatic pathology, the echographic analysis allows to determine the complete assessment of recent muscular injuries. NMR imaging can be used in granuloma or fibrous callosity appreciation and for the analysis of deep injury (muscles and muscles-tendon junctions) and of muscular aponeurosis. Echography must be used together with color coding Doppler technique in the diagnosis of tumor pathology and for the study of slow fluxes. The recently available energy Doppler technique seems to be powerful in the study of vascularization of small expansive formations, but their extension to adjacent bone or tissue can only be appreciated using NMR imaging. (J.S.)

1H NMR studies of human lysozyme: Spectral assignment and comparison with hen lysozyme

International Nuclear Information System (INIS)

Redfield, C.; Dobson, C.M.

1990-01-01

Complete main-chain (NH and αCH) 1 H NMR assignments are reported for the 130 residues of human lysozyme, along with extensive assignments for side-chain protons. Analysis of 2-D NOESY experiments shows that the regions of secondary structure for human lysozyme in solution are essentially identical with those found previously in a similar study of hen lysozyme and are in close accord with the structure of the protein reported previously from x-ray diffraction studies in the crystalline state. Comparison of the chemical shifts, spin-spin coupling constants, and hydrogen exchange behavior are also consistent with closely similar structures for the two proteins in solution. In a number of cases specific differences in the NMR parameters between hen and human lysozymes can be correlated with specific differences observed in the crystal structures

Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

DEFF Research Database (Denmark)

Hansen, Sara Krogh

2015-01-01

different and cytolytic peptides were investigated in this work. The peptides were SPF-5506-A4 from Trichoderma sp, Conolysin-Mt1 from Conus mustelinus, and Alamethicin from Trichoderma viride. The studies employed solution and solid-state NMR spectroscopy in combination with different biophysical methods...

Two New Stilbenoids from the Aerial Parts of Arundina graminifolia (Orchidaceae

Directory of Open Access Journals (Sweden)

Florence Auberon

2016-10-01

Full Text Available Two new phenanthrene derivatives, a phenanthrenequinone named arundiquinone (1 and a 9,10-dihydrophenanthrene named arundigramin (2 together with a known lignin dimer (3 and seven known stilbenoids (4–10 were isolated from the aerial parts of the Asian orchid Arundina graminifolia. The structures of the isolated compounds were elucidated by spectroscopic methods, including extensive 1D, 2D NMR (heteronuclear single quantum coherence (HSQC, heteronuclear multiple-bond correlation spectroscopy (HMBC, and HR-ESI-MS techniques, as well as comparison with respective literature reports. The cytoprotective activity of the isolated compounds were evaluated for their ability to reduce beta amyloid induced toxicity on undifferentiated PC12 cells. Compound 8 showed moderate cytoprotective activity at 0.5 µmol/L (71% of cell viability while the other compounds showed no significant activity at the highest concentration tested.

NMR Studies of Protein Hydration and Protein-Ligand Interactions

Science.gov (United States)

Chong, Yuan

Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

Development of 19F-NMR chemical shift detection of DNA B-Z equilibrium using 19F-NMR.

Science.gov (United States)

Nakamura, S; Yang, H; Hirata, C; Kersaudy, F; Fujimoto, K

2017-06-28

Various DNA conformational changes are in correlation with biological events. In particular, DNA B-Z equilibrium showed a high correlation with translation and transcription. In this study, we developed a DNA probe containing 5-trifluoromethylcytidine or 5-trifluoromethylthymidine to detect DNA B-Z equilibrium using 19 F-NMR. Its probe enabled the quantitative detection of B-, Z-, and ss-DNA based on 19 F-NMR chemical shift change.

Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

Science.gov (United States)

Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

2011-02-17

In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

Magic Angle Spinning NMR Metabolomics

Energy Technology Data Exchange (ETDEWEB)

Zhi Hu, Jian

2016-01-01

Nuclear Magnetic Resonance (NMR) spectroscopy is a non-destructive, quantitative, reproducible, untargeted and unbiased method that requires no or minimal sample preparation, and is one of the leading analytical tools for metabonomics research [1-3]. The easy quantification and the no need of prior knowledge about compounds present in a sample associated with NMR are advantageous over other techniques [1,4]. 1H NMR is especially attractive because protons are present in virtually all metabolites and its NMR sensitivity is high, enabling the simultaneous identification and monitoring of a wide range of low molecular weight metabolites.

NMR Phase Noise in Bitter Magnets

Science.gov (United States)

Sigmund, E. E.; Calder, E. S.; Thomas, G. W.; Mitrović, V. F.; Bachman, H. N.; Halperin, W. P.; Kuhns, P. L.; Reyes, A. P.

2001-02-01

We have studied the temporal instability of a high field resistive Bitter magnet through nuclear magnetic resonance (NMR). This instability leads to transverse spin decoherence in repeated and accumulated NMR experiments as is normally performed during signal averaging. We demonstrate this effect via Hahn echo and Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation experiments in a 23-T resistive magnet. Quantitative analysis was found to be consistent with separate measurements of the magnetic field frequency fluctuation spectrum, as well as with independent NMR experiments performed in a magnetic field with a controlled instability. Finally, the CPMG sequence with short pulse delays is shown to be successful in recovering the intrinsic spin-spin relaxation even in the presence of magnetic field temporal instability.

Comparing pharmacophore models derived from crystallography and NMR ensembles

Science.gov (United States)

Ghanakota, Phani; Carlson, Heather A.

2017-11-01

NMR and X-ray crystallography are the two most widely used methods for determining protein structures. Our previous study examining NMR versus X-Ray sources of protein conformations showed improved performance with NMR structures when used in our Multiple Protein Structures (MPS) method for receptor-based pharmacophores (Damm, Carlson, J Am Chem Soc 129:8225-8235, 2007). However, that work was based on a single test case, HIV-1 protease, because of the rich data available for that system. New data for more systems are available now, which calls for further examination of the effect of different sources of protein conformations. The MPS technique was applied to Growth factor receptor bound protein 2 (Grb2), Src SH2 homology domain (Src-SH2), FK506-binding protein 1A (FKBP12), and Peroxisome proliferator-activated receptor-γ (PPAR-γ). Pharmacophore models from both crystal and NMR ensembles were able to discriminate between high-affinity, low-affinity, and decoy molecules. As we found in our original study, NMR models showed optimal performance when all elements were used. The crystal models had more pharmacophore elements compared to their NMR counterparts. The crystal-based models exhibited optimum performance only when pharmacophore elements were dropped. This supports our assertion that the higher flexibility in NMR ensembles helps focus the models on the most essential interactions with the protein. Our studies suggest that the "extra" pharmacophore elements seen at the periphery in X-ray models arise as a result of decreased protein flexibility and make very little contribution to model performance.

Solid state NMR of materials

Energy Technology Data Exchange (ETDEWEB)

Taylor, Sharon A; Ferguson, David B; Haw, James F [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry

1994-12-31

In situ NMR experiments are studied, including probe of several structures such as the structures of the organic adsorbates, Broensted acid sites, other nuclei associated with active sites, and other framework sites. The authors report that in the absence of high concentrations of paramagnetic sites or metal particles, high resolution MAS spectra are relatively easy to obtain and interpret. It is also concluded that NMR can measure spatial distributions and rates of diffusion; and are able to characterize equilibrium structures and the frequencies and amplitudes of molecular motion

A 55Mn NMR Study of the La0.75Sr0.25MnO3 Nanoparticles

International Nuclear Information System (INIS)

Kapusta, Cz.; Rybicki, D.; Sikora, M.

2005-01-01

We report on a 55 Mn NMR study of the La 0.75 Sr 0.25 MnO 3 nanoparticles with the average grain size of 33 nm and 114 nm at 4.2 K and at the applied field 0, 0.2 and 0.5 T. A dominant signal from the double exchange (DE) controlled metallic ferromagnetic interior of the grains as well as a small signal from insulating ferromagnetic surface regions of the grains are observed. The DE resonant line shows a frequency shift in the applied field according to a full gyromagnetic ratio and a value of the demagnetizing field much smaller than 0.2 T is obtained. In both samples studied a two-exponential nuclear spin-spin (T 2 ) relaxation is observed at zero field, whereas a single-exponential relaxation is observed at the applied field of 0.5 T. For the sample with larger grains a higher NMR enhancement is observed, which indicates a higher magnetic susceptibility of the sample at the NMR frequencies. A comparison to the NMR data obtained on a bulk material is made. The results are discussed in terms of the influence of the grain size and on the presence of domain walls or other magnetic inhomogeneities and on the magnetic anisotropy

Experimental (FT-IR, FT-Raman, 1H, 13C NMR) and theoretical study of alkali metal 2-aminobenzoates

Science.gov (United States)

Samsonowicz, M.; Świsłocka, R.; Regulska, E.; Lewandowski, W.

2008-09-01

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-aminobenzoic acid was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-aminobenzoic acid and its alkali metal salts were recorded. The assignment of vibrational spectra was done on the basis of literature data, theoretical calculations and our previous experience. Characteristic shifts of bands and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons ( 1H NMR) and carbons ( 13C NMR) in the series of studied alkali metal 2-aminobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G ∗∗ basis set. Geometric aromaticity indices, dipole moments and energies were also calculated. The theoretical wavenumbers and intensities of IR and Raman spectra were obtained. The calculated parameters were compared to experimental characteristic of studied compounds.

MRI and unilateral NMR study of reindeer skin tanning processes.

Science.gov (United States)

Zhu, Lizheng; Del Federico, Eleonora; Ilott, Andrew J; Klokkernes, Torunn; Kehlet, Cindie; Jerschow, Alexej

2015-04-07

The study of arctic or subarctic indigenous skin clothing material, known for its design and ability to keep the body warm, provides information about the tanning materials and techniques. The study also provides clues about the culture that created it, since tanning processes are often specific to certain indigenous groups. Untreated skin samples and samples treated with willow (Salix sp) bark extract and cod liver oil are compared in this study using both MRI and unilateral NMR techniques. The two types of samples show different proton spatial distributions and different relaxation times, which may also provide information about the tanning technique and aging behavior.

NMR investigations of molecular dynamics

Science.gov (United States)

Palmer, Arthur

2011-03-01

NMR spectroscopy is a powerful experimental approach for characterizing protein conformational dynamics on multiple time scales. The insights obtained from NMR studies are complemented and by molecular dynamics (MD) simulations, which provide full atomistic details of protein dynamics. Homologous mesophilic (E. coli) and thermophilic (T. thermophilus) ribonuclease H (RNase H) enzymes serve to illustrate how changes in protein sequence and structure that affect conformational dynamic processes can be monitored and characterized by joint analysis of NMR spectroscopy and MD simulations. A Gly residue inserted within a putative hinge between helices B and C is conserved among thermophilic RNases H, but absent in mesophilic RNases H. Experimental spin relaxation measurements show that the dynamic properties of T. thermophilus RNase H are recapitulated in E. coli RNase H by insertion of a Gly residue between helices B and C. Additional specific intramolecular interactions that modulate backbone and sidechain dynamical properties of the Gly-rich loop and of the conserved Trp residue flanking the Gly insertion site have been identified using MD simulations and subsequently confirmed by NMR spin relaxation measurements. These results emphasize the importance of hydrogen bonds and local steric interactions in restricting conformational fluctuations, and the absence of such interactions in allowing conformational adaptation to substrate binding.

NMR study of thermoresponsive block copolymer in aqueous solution

Czech Academy of Sciences Publication Activity Database

Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

2016-01-01

Roč. 217, č. 12 (2016), s. 1370-1375 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * NMR * NOESY Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy

International Nuclear Information System (INIS)

Fossell, E.T.; Hall, F.M.; McDonagh, J.

1991-01-01

The authors have previously described the application of water-suppressed proton nuclear magnetic resonance (H-1 NMR) spectroscopy of plasma for detection of malignancy. Subsequently, hypertriglyceridemia has been identified as a source of false positive results. Here is described a confirmatory, adjunctive technique -analysis of the carbon-13 (C-13) NMR spectrum of plasma- which also identifies the presence of malignancy but is not sensitive to the plasma triglyceride level. Blinded plasma samples from 480 normal donors and 208 patients scheduled for breast biopsy were analyzed by water-suppressed H-1 and C-13 NMR spectroscopy. Triglyceride levels were also measured. Among the normal donors, there were 38 individuals with hypertriglyceridemia of whom 18 had results consistent with malignancy by H-1 NMR spectroscopy. However, the C-13 technique reduced the apparent H-1 false positive rate from 7.0 to 0.6 percent. Similarly, in the breast biopsy cohort, C-13 reduced the false positive rate from 2.8 to 0.9 percent. Furthermore, the accuracy of the combined H-1/C-13 test in this blinded study was greater than 96 percent in 208 patients studied. (author). 27 refs.; 5 figs.; 4 tabs

Selected topics in solution-phase biomolecular NMR spectroscopy

Science.gov (United States)

Kay, Lewis E.; Frydman, Lucio

2017-05-01

Solution bio-NMR spectroscopy continues to enjoy a preeminent role as an important tool in elucidating the structure and dynamics of a range of important biomolecules and in relating these to function. Equally impressive is how NMR continues to 'reinvent' itself through the efforts of many brilliant practitioners who ask increasingly demanding and increasingly biologically relevant questions. The ability to manipulate spin Hamiltonians - almost at will - to dissect the information of interest contributes to the success of the endeavor and ensures that the NMR technology will be well poised to contribute to as yet unknown frontiers in the future. As a tribute to the versatility of solution NMR in biomolecular studies and to the continued rapid advances in the field we present a Virtual Special Issue (VSI) that includes over 40 articles on various aspects of solution-state biomolecular NMR that have been published in the Journal of Magnetic Resonance in the past 7 years. These, in total, help celebrate the achievements of this vibrant field.

Structural biology by NMR: structure, dynamics, and interactions.

Directory of Open Access Journals (Sweden)

Phineus R L Markwick

2008-09-01

Full Text Available The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to structural features and to dynamics, and hence the measured data contain information on both. Despite major progress in both experimental approaches and computational methods, obtaining a consistent view of structure and dynamics from experimental NMR data remains a challenge. Molecular dynamics simulations have emerged as an indispensable tool in the analysis of NMR data.

Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy.

Science.gov (United States)

Konuma, Tsuyoshi; Harada, Erisa; Sugase, Kenji

2015-12-01

Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis.

Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Konuma, Tsuyoshi [Icahn School of Medicine at Mount Sinai, Department of Structural and Chemical Biology (United States); Harada, Erisa [Suntory Foundation for Life Sciences, Bioorganic Research Institute (Japan); Sugase, Kenji, E-mail: sugase@sunbor.or.jp, E-mail: sugase@moleng.kyoto-u.ac.jp [Kyoto University, Department of Molecular Engineering, Graduate School of Engineering (Japan)

2015-12-15

Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis.

NMR imaging of the brain: initial impressions

International Nuclear Information System (INIS)

Spencer, D.H.; Bydder, G.M.

1983-01-01

An NMR imaging system designed and built by Thorn-EMI Ltd was installed at Hammersmith Hospital in March 1981. In the first year of operation 180 patients and 40 volunteers have had cranial examinations and initial impressions bases on this experience are presented. Patients with a wide variety of neurological diseases have been studied to provide a basis for diagnostic interpretation, to define distinctive features, and to evaluate different types of scanning sequences. NMR imaging appears to be of considerable value in neurological diagnosis and has a number of advantages over CT. The detailed evaluation of NMR imaging will require much more work but the initial results are very promising

Graphical programming for pulse automated NMR experiments

International Nuclear Information System (INIS)

Belmonte, S.B.; Oliveira, I.S.; Guimaraes, A.P.

1999-01-01

We describe a software program designed to control a broadband pulse Nuclear Magnetic Resonance (NMR) spectrometer used in zero-field NMR studies of magnetic metals. The software is written in the graphical language LabVIEW. This type of programming allows modifications and the inclusion of new routines to be easily made by the non-specialist, without changing the basic structure of the program. The program corrects for differences in the gain of the two acquisition channels [U (phase) and V (quadrature)], and automatic baseline subtraction. We present examples of measurements of NMR spectra, spin-echo decay (T 2 ), and quadrupolar oscillations, performed in magnetic intermetallic compounds. (author)

Metabolic engineering applications of in vivo 31P and 13C NMR studies of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Shanks, J.V.

1989-01-01

With intent to quantify NMR measurements as much as possible, analysis techniques of the in vivo 31 P NMR spectrum are developed. A systematic procedure is formulated for estimating the relative intracellular concentrations of the sugar phosphates in S. cerevisiae from the 31 P NMR spectrum. In addition, in vivo correlation of inorganic phosphate chemical shift with the chemical shifts of 3-phosphoglycerate, β-fructose 1,6-diphosphate, fructose 6-phosphate, and glucose 6-phosphate are determined. Also, a method was developed for elucidation of the cytoplasmic and vacuolar components of inorganic phosphate in the 31 P NMR spectrum of S. cerevisiae. An in vivo correlation relating the inorganic phosphate chemical shift of the vacuole with the chemical shift of the resonance for pyrophosphate and the terminal phosphate of polyphosphate (PP 1 ) is established. Transient measurements provided by 31 P NMR are applied to reg1 mutant and standard strains. 31 P and 13 C NMR measurements are used to analyze the performance of recombinant strains in which the glucose phosphorylation step had been altered

Chemical shift assignments of the first and second RRMs of Nrd1, a fission yeast MAPK-target RNA binding protein.

Science.gov (United States)

Kobayashi, Ayaho; Kanaba, Teppei; Satoh, Ryosuke; Ito, Yutaka; Sugiura, Reiko; Mishima, Masaki

2017-10-01

Negative regulator differentiation 1 (Nrd1), a fission yeast RNA binding protein, modulates cytokinesis and sexual development and contributes to stress granule formation in response to environmental stresses. Nrd1 comprises four RRM domains and binds and stabilizes Cdc4 mRNA that encodes the myosin II light chain. Nrd1 binds the Cpc2 fission-yeast RACK1 homolog, and the interaction promotes Nrd1 localization to stress granules. Interestingly, Pmk1 mitogen-activated protein kinase phosphorylates Thr40 in the unstructured N-terminal region and Thr126 in the first RRM domain of Nrd1. Phosphorylation significantly reduces RNA-binding activity and likely modulates Nrd1 function. To reveal the relationship between the structure and function of Nrd1 and how phosphorylation affects structure, we used heteronuclear NMR techniques to investigate the three-dimensional structure of Nrd1. Here we report the 1 H, 13 C, and 15 N resonance assignments of RRM1-RRM2 (residues 108-284) comprising the first and second RRMs obtained using heteronuclear NMR techniques. Secondary structures derived from the chemical shifts are reported. These data should contribute to the understanding of the three-dimensional structure of the RRM1-RRM2 region of Nrd1 and the perturbation caused by phosphorylation.

Comparative magnetic studies of (Sm, Nd) trichloroacetates and their heteronuclear CuLn2(CCl3COO)8.6H2O systems: structure and spectroscopy of a new type of Eu trichloroacetate

International Nuclear Information System (INIS)

Wojciechowski, W.; Legendziewicz, J.; Puchalska, M.; Ciunik, Z.

2004-01-01

Two series of compounds: heteronuclear CuLn 2 (CCl 3 COO) 8 .6H 2 O (Ln = Nd and Sm) and their simple analogues Ln(CCl 3 COO) 3 .2H 2 O (Ln = Eu, Nd, Sm) were synthesized. New Eu(III) trichloroacetate; Eu(CCl 3 COO) 3 .3H 2 O.CH 3 OH was obtained, its molecular structure was determined by X-ray diffraction and compared with the data of respective systems reported earlier. Magnetization was measured and the susceptibility was derived in the limit of low field. Magnetic susceptibilities were calculated and discussed for series of homo- and hetero-nuclear chloroacetates.Untypical hysteresis was found (two loops) in samarium trichloroacetate. This phenomenon is most probably the effect of flops of spins in magnetic fields of 30,000Oe and very weak (if any) interaction intermediated by weak hydrogen bonding between the chains. A similar magnetic behavior was observed in neodymium carboxylate where the magnetic ordering was observed as a result of Nd-Nd interaction at low temperature (1.6K). For this system, the magnetic moment depends on magnitude of the magnetic field and ferromagnetic ordering appears at low temperatures. The strongest interactions of coupled ions and antiferromagnetic ordering with T N =6.5K were found in CuSm 2 (CCl 3 COO) 8 .6H 2 O single crystals.Heisenberg model was applied in the calculations for three interacting ions located linearly. The following relation was derived: χ M =Ng 2 μ β 2 kT(12)+(12)exp(J 2 /kT)+5exp(J 2 /kT)-exp(1,5J 1 /kT)2+2exp(J 2 /kT)+4exp(J 2 /kT)-exp(1,5J 1 /kT) and applied in calculations of the exchange integrals. Mechanism of the exchange interaction was discussed on the basis of the obtained results.

Detergent/nanodisc screening for high-resolution NMR studies of an integral membrane protein containing a cytoplasmic domain.

Directory of Open Access Journals (Sweden)

Christos Tzitzilonis

Full Text Available Because membrane proteins need to be extracted from their natural environment and reconstituted in artificial milieus for the 3D structure determination by X-ray crystallography or NMR, the search for membrane mimetic that conserve the native structure and functional activities remains challenging. We demonstrate here a detergent/nanodisc screening study by NMR of the bacterial α-helical membrane protein YgaP containing a cytoplasmic rhodanese domain. The analysis of 2D [(15N,(1H]-TROSY spectra shows that only a careful usage of low amounts of mixed detergents did not perturb the cytoplasmic domain while solubilizing in parallel the transmembrane segments with good spectral quality. In contrast, the incorporation of YgaP into nanodiscs appeared to be straightforward and yielded a surprisingly high quality [(15N,(1H]-TROSY spectrum opening an avenue for the structural studies of a helical membrane protein in a bilayer system by solution state NMR.

observed by high pressure NMR and NQR

Indian Academy of Sciences (India)

Akogun, Hyogo 678-1297, Japan. ∗. Email: kohara@sci.himeji tech.ac.jp. Abstract. NMR and NQR studies on two interesting systems (URu2Si2, CeTIn5) were performed under high pressure. (1) URu2Si2: In the pressure range 3.0 to 8.3 kbar, we have observed new 29Si. NMR signals arising from the antiferromagnetic ...

Chemical study of ethyl Acetate fraction of Picrasma Javanica Bl.

Directory of Open Access Journals (Sweden)

Sri Hainil

2015-12-01

Full Text Available N-1 main compound from ethyl acetate fraction of kayu pahit bark (Picrasma Javanica B1 has been isolated and characterized with colom chromatography and continued with preparative chromatography. According to analized from spectrum data used ultraviolet (UV spectroscopy, infra red (IR, 1H RMI (Resonansi Magnet Inti, 13 C RMI, Massa , COSY (Correlated Spectroscopy, HSQC (Heteronuclear Single Quantum Correlation, HMBC ( Heteronuclear Multiple Bond Correlation and literature study showed that the compound of isolation was javanicin A.

NMR imaging of human atherosclerosis

International Nuclear Information System (INIS)

Toussaint, J.F.

1995-01-01

Diagnosis and prognosis of atherosclerosis can no longer be evaluated with morphological parameters only. A description of atherosclerotic plaque composition is necessary to study the mechanisms of plaque rupture, which depends on collagenous cap and lipid core thicknesses. NMR, as a biochemical imaging technique, allows visualization of these components using T1 contrast (mobile lipids), T2 contrast (cap vs. core), spin density (calcifications), diffusion imaging, 1H and 13C spectroscopy. Today, these imaging sequences allow to study in vitro the effects of interventional techniques such as angioplasty or atherectomy. Clinical investigations begin, which will attempt to develop in vivo microscopy and test the ability of NMR to predict plaque rupture. (author). 13 refs., 7 figs

Intracellular PHB conversion in a type II methanotroph studied by 13 C NMR

NARCIS (Netherlands)

Vecherskaya, M.; Dijkema, C.; Stams, A.J.M.

2001-01-01

Poly-g-hydroxybutyrate (PHB) formation under aerobic conditions via incorporation of [13C-2]acetate as a cosubstrate and its intracellular degradation under anaerobic conditions in a Type II methanotroph was studied by 13C NMR. During PHB synthesis in the presence of labelled acetate, low levels of

Multinuclear NMR studies of single lipid bilayers supported in cylindrical aluminum oxide nanopores.

Science.gov (United States)

Gaede, Holly C; Luckett, Keith M; Polozov, Ivan V; Gawrisch, Klaus

2004-08-31

Lipid bilayers were deposited inside the 0.2 microm pores of anodic aluminum oxide (AAO) filters by extrusion of multilamellar liposomes and their properties studied by 2H, 31P, and 1H solid-state NMR. Only the first bilayer adhered strongly to the inner surface of the pores. Additional layers were washed out easily by a flow of water as demonstrated by 1H magic angle spinning NMR experiments with addition of Pr3+ ions to shift accessible lipid headgroup resonances. A 13 mm diameter Anopore filter of 60 microm thickness oriented approximately 2.5 x 10(-7) mol of lipid as a single bilayer, corresponding to a total membrane area of about 500 cm2. The 2H NMR spectra of chain deuterated POPC are consistent with adsorption of wavy, tubular bilayers to the inner pore surface. By NMR diffusion experiments, we determined the average length of those lipid tubules to be approximately 0.4 microm. There is evidence for a thick water layer between lipid tubules and the pore surface. The ends of tubules are well sealed against the pore such that Pr3+ ions cannot penetrate into the water underneath the bilayers. We successfully trapped poly(ethylene glycol) (PEG) with a molecular weight of 8000 in this water layer. From the quantity of trapped PEG, we calculated an average water layer thickness of 3 nm. Lipid order parameters and motional properties are unperturbed by the solid support, in agreement with existence of a water layer. Such unperturbed, solid supported membranes are ideal for incorporation of membrane-spanning proteins with large intra- and extracellular domains. The experiments suggest the promise of such porous filters as membrane support in biosensors.

Microprocessorized NMR measurement

International Nuclear Information System (INIS)

Rijllart, A.

1984-01-01

An MC68000 CAMAC microprocessor system for fast and accurate NMR signal measurement will be presented. A stand-alone CAMAC microprocessor system (MC68000 STAC) with a special purpose interface sweeps a digital frequency synthesizer and digitizes the NMR signal with a 16-bit ADC of 17 μs conversion time. It averages the NMR signal data over many sweeps and then transfers it through CAMAC to a computer for calculation of the signal parameters. The computer has full software control over the timing and sweep settings of this signal averager, and thus allows optimization of noise suppression. Several of these processor systems can be installed in the same crate for parallel processing, and the flexibility of the STAC also allows easy adaptation to other applications such as transient recording or phase-sensitive detection. (orig.)

NMR Techniques in Metabolomic Studies: A Quick Overview on Examples of Utilization.

Science.gov (United States)

Kruk, Joanna; Doskocz, Marek; Jodłowska, Elżbieta; Zacharzewska, Anna; Łakomiec, Joanna; Czaja, Kornelia; Kujawski, Jacek

2017-01-01

Metabolomics is a rapidly developing branch of science that concentrates on identifying biologically active molecules with potential biomarker properties. To define the best biomarkers for diseases, metabolomics uses both models (in vitro, animals) and human, as well as, various techniques such as mass spectroscopy, gas chromatography, liquid chromatography, infrared and UV-VIS spectroscopy and nuclear magnetic resonance. The last one takes advantage of the magnetic properties of certain nuclei, such as 1 H, 13 C, 31 P, 19 F, especially their ability to absorb and emit energy, what is crucial for analyzing samples. Among many spectroscopic NMR techniques not only one-dimensional (1D) techniques are known, but for many years two-dimensional (2D, for example, COSY, DOSY, JRES, HETCORE, HMQS), three-dimensional (3D, DART-MS, HRMAS, HSQC, HMBC) and solid-state NMR have been used. In this paper, authors taking apart fundamental division of nuclear magnetic resonance techniques intend to shown their wide application in metabolomic studies, especially in identifying biomarkers.

Fourier transform n.m.r. spectroscopy

International Nuclear Information System (INIS)

Shaw, D.

1976-01-01

This book is orientated to techniques rather than applications. The basic theory of n.m.r. is dealt with in a unified approach to the Fourier theory. The middle section of the book concentrates on the practical aspects of Fourier n.m.r., both instrumental and experimental. The final chapters briefly cover general application of n.m.r., but concentrate strongly on those areas where Fourier n.m.r. can give information which is not available by conventional techniques

Metabonomic study of human serum in gallbladder cancer by 1H NMR spectroscopy

International Nuclear Information System (INIS)

Sonkar, Kanchan; Sinha, Neeraj; Behari, Anu; Kapoor, V.K.

2012-01-01

Gallbladder carcinoma (GBC) is one of the most lethal malignancies of upper gastrointestinal tract and it has the highest mortality rate in Chile and India. It has a very high incidence rates in northern India therefore it is also called as an Indian disease. There are several factors which play important role in development of gallbladder cancer including long-standing stones in gallbladder and alterations in composition of bile. Studies on gallstones and gallbladder tissues revealed that benign group can easily be discriminated from malignant group. Many proteomic studies have been performed for different cancers and several responsible serum protein markers have been identified but there is no such metabonomics study that shows the presence of any biomarker associated with gallbladder carcinoma. Identification of such biomarker would help immensely in the diagnostic of GBC. For this study we have collected blood samples (70; including patients from Chronic Cholecystitis (CC), XanthoGranulomatous Cholecystitis (XGC) and Gallbladder Cancer (GBC)) post-operatively (immediately after surgery) from patient undergoing cholecystectomy in Department of Surgical Gastroenterology, SGPGIMS. Control samples were also collected from 20 volunteers after 12 hrs of fasting. 4 ml of blood sample was collected and was allowed to clot in plastic tube for 30 min at room temperature in incubator. The serum was collected by centrifugation and samples were stored at -80 deg C till NMR experiments. 400 μL of serum was used for recording NMR spectra. NMR spectra were recorded at Bruker Avance 800 MHz spectrometer using CPMG pulse sequence with water presaturation. Control serum shows presence of various amino acids and low molecular weight metabolites. Detailed multivariate analysis along with markers found in serum associated with GBC will be presented. (author)

NMR studies of actinide carbide and nitride electronic properties

International Nuclear Information System (INIS)

Boutard, Jean-Louis

1976-12-01

N.M.R. studies applied to 13 C and 15 N in the solid solutions ThCsub(1-x)Nsub(x), UCsub(1-x)Nsub(x) and in the compounds ThCsub(1-x) and U 2 C 3 , were undertaken to study carbon and nitrogen contribution to chemical bonds and magnetism. For THORIUM MONOCARBIDE AND CARBONITRIDE: ThCsub(1-x) and ThCsub(1-x)Nsub(x), the very strong orbital contribution to the frequency shift reveals an important covalent character of the valence band 6d metal and 2p metalloid states. The ThCsub(1-x) band structure stoichiometry variation is due to 6dγ metal states appearing at the Fermi level and is in-opposition to a rigid band model. A non-saturated bond mechanism is suggested. For URANIUM CARBONITRIDE: UCsub(1-x)Nsub(x), in the concentration range in which no magnetic order appears at low temperature (x<0.90), the results are in opposition to a localized 5f 2 configuration model, and show that the uranium fundamental state is non-magnetic. Nevertheless two qualitatively different behaviors exist: nitrogen concentration lower than 40%: and nitrogen concentration higher than 40%. A model is proposed to account for those domains: it relies on the 5f-2p hybridization parameter which is maximum on 2p band edge (UC) and almost nul for UN. For URANIUM SESQUICARBIDE: U 2 C 3 : the N.M.R. line observation at 4.2 K indicates a non-magnetic fundamental state although the magnetic susceptibility presents a maximum at 60 K. Spin fluctuations in 5f bands are proposed to describe the electronic properties of this compound. [fr

Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

Science.gov (United States)

Kamal, Ghulam Mustafa; Wang, Xiaohua; Bin Yuan; Wang, Jie; Sun, Peng; Zhang, Xu; Liu, Maili

2016-09-01

Soy sauce a well known seasoning all over the world, especially in Asia, is available in global market in a wide range of types based on its purpose and the processing methods. Its composition varies with respect to the fermentation processes and addition of additives, preservatives and flavor enhancers. A comprehensive (1)H NMR based study regarding the metabonomic variations of soy sauce to differentiate among different types of soy sauce available on the global market has been limited due to the complexity of the mixture. In present study, (13)C NMR spectroscopy coupled with multivariate statistical data analysis like principle component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) was applied to investigate metabonomic variations among different types of soy sauce, namely super light, super dark, red cooking and mushroom soy sauce. The main additives in soy sauce like glutamate, sucrose and glucose were easily distinguished and quantified using (13)C NMR spectroscopy which were otherwise difficult to be assigned and quantified due to serious signal overlaps in (1)H NMR spectra. The significantly higher concentration of sucrose in dark, red cooking and mushroom flavored soy sauce can directly be linked to the addition of caramel in soy sauce. Similarly, significantly higher level of glutamate in super light as compared to super dark and mushroom flavored soy sauce may come from the addition of monosodium glutamate. The study highlights the potentiality of (13)C NMR based metabonomics coupled with multivariate statistical data analysis in differentiating between the types of soy sauce on the basis of level of additives, raw materials and fermentation procedures. Copyright © 2016 Elsevier B.V. All rights reserved.

Positional isotope exchange studies on enzyme using NMR spectroscopy

International Nuclear Information System (INIS)

Matsunaga, T.O.

1987-01-01

The isotopically enriched compounds, 18 O-β,γ-ATP and 18 O bridge-labeled pyrophosphate, synthesized previously in this laboratory, were used to investigate and measure the exchange vs. turnover of substrates and products from their central complexes in four selected enzyme systems. Using hi-field 31 P NMR, we were able to differentiate between 18 O labeled in the bridge vs. the non-bridge positions by virtue of the isotope shift upon the phosphorus nuclei. The bridge to non-bridge scrambling of the label was quantitated and the exchange vs. turnover ratios under a variety of conditions was determined. Using the substrate inhibitor carboxycreatinine, PIX experiments with 18 O-β,γ-ATP and creatine kinase were conducted. It was shown that carboxycreatinine and creatine kinase promoted exchange of the 18 O label as determined by NMR. We have concluded that carboxycreatinine is either a substrate that catalyzes very slow turnover or it catalyzes exchange by a dissociative (SN 1 /sub P/) type of mechanism

23Na+- and 39K+-NMR studies of cation-polyanion interactions in vascular connective tissue

International Nuclear Information System (INIS)

Siegel, G.; Walter, A.; Bostanjoglo, M.

1987-01-01

The ion binding properties of vascular connective tissue as well as of substances derived therefrom were studied in dependence on cation concentration by NMR and atomic absorption techniques. 16 refs.; 8 figs

High resolution NMR theory and chemical applications

CERN Document Server

Becker, Edwin D

2012-01-01

High Resolution NMR: Theory and Chemical Applications discusses the principles and theory of nuclear magnetic resonance and how this concept is used in the chemical sciences. This book is written at an intermediate level, with mathematics used to augment verbal descriptions of the phenomena. This text pays attention to developing and interrelating four approaches - the steady state energy levels, the rotating vector picture, the density matrix, and the product operator formalism. The style of this book is based on the assumption that the reader has an acquaintance with the general principles of quantum mechanics, but no extensive background in quantum theory or proficiency in mathematics is required. This book begins with a description of the basic physics, together with a brief account of the historical development of the field. It looks at the study of NMR in liquids, including high resolution NMR in the solid state and the principles of NMR imaging and localized spectroscopy. This book is intended to assis...

13C and 17O NMR binding constant studies of uranyl carbonate complexes in near-neutral aqueous solution. Yucca Mountain Project Milestone Report 3351

International Nuclear Information System (INIS)

Clark, D.L.; Newton, T.W.; Palmer, P.D.; Zwick, B.D.

1995-01-01

Valuable structural information, much of it unavailable by other methods, can be obtained about complexes in solution through NMR spectroscopy. From chemical shift and intensity measurements of complexed species, NMR can serve as a species-specific structural probe for molecules in solution and can be used to validate thermodynamic constants used in geochemical modeling. Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy has been employed to study the speciation of uranium(VI) ions in aqueous carbonate solutions as a function of pH, ionic strength, carbonate concentration, uranium concentration, and temperature. Carbon-13 and oxygen-17 NMR spectroscopy were used to monitor the fractions, and hence thermodynamic binding constants of two different uranyl species U0 2 (CO 3 ) 3 4- and (UO 2 ) 3 (CO 3 ) 6 6- in aqueous solution. Synthetic buffer solutions were prepared under the ionic strength conditions used in the NMR studies in order to obtain an accurate measure of the hydrogen ion concentration, and a discussion of pH = -log(a H + ) versus p[H] = -log[H+] is provided. It is shown that for quantitative studies, the quantity p[H] needs to be used. Fourteen uranium(VI) binding constants recommended by the OECD NEA literature review were corrected to the ionic strengths employed in the NMR study using specific ion interaction theory (SIT), and the predicted species distributions were compared with the actual species observed by multinuclear NMR. Agreement between observed and predicted stability fields is excellent. This establishes the utility of multinuclear NMR as a species-specific tool for the study of the actinide carbonate complexation constants, and serves as a means for validating the recommendations provided by the OECD NEA