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Sample records for 13c nmr spectroscopy

  1. Insights into the metabolic response to traumatic brain injury as revealed by 13C NMR spectroscopy.

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    Brenda eBartnik-Olson

    2013-10-01

    Full Text Available The present review highlights critical issues related to cerebral metabolism following traumatic brain injury (TBI and the use of 13C labeled substrates and nuclear magnetic resonance (NMR spectroscopy to study these changes. First we address some pathophysiologic factors contributing to metabolic dysfunction following TBI. We then examine how 13C NMR spectroscopy strategies have been used to investigate energy metabolism, neurotransmission, the intracellular redox state, and neuroglial compartmentation following injury. 13C NMR spectroscopy studies of brain extracts from animal models of TBI have revealed enhanced glycolytic production of lactate, evidence of pentose phosphate pathway (PPP activation, and alterations in neuronal and astrocyte oxidative metabolism that are dependent on injury severity. Differential incorporation of label into glutamate and glutamine from 13C labeled glucose or acetate also suggest TBI-induced adaptations to the glutamate-glutamine cycle.

  2. Coal structure at reactive sites by sup 1 H- sup 13 C- sup 19 F double cross polarization (DCP)/MAS sup 13 C NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hagaman, E.W.; Woody, M.C. (Oak Ridge National Lab., TN (USA))

    1989-01-01

    The solid state NMR technique, {sup 1}H-{sup 13}C-{sup 31}P double cross polarization (DCP)/MAS {sup 13}C-NMR spectroscopy, uses the direct dipolar interaction between {sup 13}C-{sup 31}P spin pairs in organophosphorus substances to identify the subset of carbons within a spherical volume element of 0.4 nm radius centered on the {sup 31}P atom. In combination with chemical manipulation of coals designed to introduce phosphorus containing functionality into the organic matrix, the NMR experiment becomes a method to examine selectively the carbon bonding network at the reactive sites in the coal. This approach generates a statistical structure description of the coal at the reaction centers in contrast to bulk carbon characterization using conventional {sup 1}H-{sup 13}C CP/MAS {sup 13}C NMR spectroscopy. 3 refs.

  3. (13)C NMR assignments of regenerated cellulose from solid-state 2D NMR spectroscopy.

    Science.gov (United States)

    Idström, Alexander; Schantz, Staffan; Sundberg, Johan; Chmelka, Bradley F; Gatenholm, Paul; Nordstierna, Lars

    2016-10-20

    From the assignment of the solid-state (13)C NMR signals in the C4 region, distinct types of crystalline cellulose, cellulose at crystalline surfaces, and disordered cellulose can be identified and quantified. For regenerated cellulose, complete (13)C assignments of the other carbon regions have not previously been attainable, due to signal overlap. In this study, two-dimensional (2D) NMR correlation methods were used to resolve and assign (13)C signals for all carbon atoms in regenerated cellulose. (13)C-enriched bacterial nanocellulose was biosynthesized, dissolved, and coagulated as highly crystalline cellulose II. Specifically, four distinct (13)C signals were observed corresponding to conformationally different anhydroglucose units: two signals assigned to crystalline moieties and two signals assigned to non-crystalline species. The C1, C4 and C6 regions for cellulose II were fully examined by global spectral deconvolution, which yielded qualitative trends of the relative populations of the different cellulose moieties, as a function of wetting and drying treatments. PMID:27474592

  4. Protolytic properties of polyamine wasp toxin analogues studied by 13C NMR spectroscopy

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Piazzi, Lorna; Olsen, Christian A;

    2006-01-01

    Acid-base properties of the natural polyamine wasp toxin PhTX-433 (1) and seven synthetic analogues [PhTX-343 (2), PhTX-334 (3), PhTX-443 (4), PhTX-434 (5), PhTX-344 (6), PhTX-444 (7), and PhTX-333 (8)], each having four protolytic sites, were characterized by 13C NMR spectroscopy. Nonlinear, mul...

  5. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    Science.gov (United States)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (γ), such as protons, to the less abundant 13C nuclei with low γ values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; Kögel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90° x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched

  6. Structural characteristics of marine sedimentary humic acids by CP/MAS sup(13)C NMR spectroscopy

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; Wahidullah, S.

    Humic acids from sediments of different depositional environments have been studied by solid-state sup(13)C NMR and the results compared with the traditional wet chemical analysis. Results obtained are well in agreement with the previous literature...

  7. Compartmentalised cerebral metabolism of [1,6-13C]glucose determined by in vivo 13C NMR spectroscopy at 14.1 T

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    João M.N. Duarte

    2011-06-01

    Full Text Available Cerebral metabolism is compartmentalised between neurons and glia. Although glial glycolysis is thought to largely sustain the energetic requirements of neurotransmission while oxidative metabolism takes place mainly in neurons, this hypothesis is matter of debate. The compartmentalization of cerebral metabolic fluxes can be determined by 13C NMR spectroscopy upon infusion of 13C-enriched compounds, especially glucose. Rats under light α-chloralose anaesthesia were infused with [1,6-13C]glucose and 13C enrichment in the brain metabolites was measured by 13C NMR spectroscopy with high sensitivity and spectral resolution at 14.1 T. This allowed determining 13C enrichment curves of amino acid carbons with high reproducibility and to reliably estimate cerebral metabolic fluxes (mean error of 8%. We further found that TCA cycle intermediates are not required for flux determination in mathematical models of brain metabolism. Neuronal tricarboxylic acid cycle rate (VTCA and neurotransmission rate (VNT were 0.45±0.01 and 0.11±0.01 µmol/g/min, respectively. Glial VTCA was found to be for 38±3% of total cerebral oxidative metabolism, accounting for more than half of neuronal oxidative metabolism. Furthermore, glial anaplerotic pyruvate carboxylation rate (VPC was 0.069±0.004 µmol/g/min, i.e. 25±1% of the glial TCA cycle rate. These results support a role of glial cells as active partners of neurons during synaptic transmission beyond glycolytic metabolism.

  8. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

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    Gaspare Cesarano

    Full Text Available Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  9. High-field magic-angle spinning 13C NMR spectroscopy of Co4(CO)12

    International Nuclear Information System (INIS)

    The high-field (68-MHz) 13C MAS NMR spectra of solid Co4(CO)12 is reported at three different spinning rates. The different spinning rates were required to allow the separation of sidebands from centerbands in the spectrum. This NMR study resulted in the observation of signal(s) due to bridging carbonyls as required by either a dynamic or static Co4(CO)12 structure. The failure to previously observe bridging carbonyl resonances at low field is thought to be most likely due to residual coupling to the quadrupolar cobalt nucleus and/or rapid and selective scalar relaxation of the carbonyl ligand by the cobalt cation. 22 refs., 3 figs

  10. Metabolite Characterization in Peritoneal Dialysis Effluent Using High-resolution 1H and 1H-13C NMR Spectroscopy

    CERN Document Server

    Guleria, Anupam; Rawat, Atul; Khetrapal, C L; Prasad, Narayan; Kumar, Dinesh

    2014-01-01

    Metabolite analysis of peritoneal dialysis (PD) effluent may provide information regarding onset and progression of complications associated with prolonged PD therapy. In this context, the NMR detectable small metabolites of PD effluent samples were characterized using high resolution 1H and 1H-13C NMR spectroscopy. The various spectra were recorded (at 800 MHz proton frequency) on PD effluent samples obtained after 4 hour (intraperitoneal) dwell time from patients with end stage renal failure (ESRF) and continuing normally on PD therapy. Inspite of devastating spectral feature of PD effluent due to the presence of intense resonances from glucose and lactate, we were able to identify about 53 small endogenous metabolites (including many complex coupled spin systems) and more than 90 % of the total CH cross peaks of 1H-13C HSQC spectrum were identified specific to various metabolites of PD effluent. We foresee that the characteristic fingerprints of various metabolites of control PD effluent samples will be us...

  11. 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. PMID:27343582

  12. Application of 13C NMR spectroscopy to characterize organic chemical components of decomposing coarse woody debris from different climatic regions

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    Takuya Hishinuma

    2015-04-01

    Full Text Available Solid-state 13C nuclear magnetic resonance (NMR spectroscopy was applied to coarse woody debris (CWD in different stages of decomposition and collected from forest floor of a subtropical, a cool temperate, and a subalpine forest in Japan. The purpose was to test its applicability to characterize organic chemical composition of CWD of broad-leaved and coniferous trees from different climatic conditions. O-alkyl-C, mainly representing carbohydrates, was the predominant component of CWD at the three sites, accounting for 43.5-58.1% of the NMR spectra. Generally, the relative area under the signals for aromatic-C and phenolic-C, mainly representing lignin, increased, whereas the relative area for O-alkyl-C decreased, as the decay class advanced. The relative area under NMR chemical shift regions was significantly correlated with the chemical properties examined with proximate analyses. That is, O-alkyl-C and di-O-alkyl-C NMR signal areas were positively correlated with the volumetric density of CWD and the content of total carbohydrates. Methoxyl-C, aromatic-C, phenolic-C, carboxyl-C, and carbonyl-C were positively correlated with the contents of acid-unhydrolyzable residues (lignin, tannins, and cutin and nitrogen. Lignin-C calculated from NMR signals increased, and polysaccharide-C decreased, with the decay class of CWD at the three study sites. A review of previous studies on 13C NMR spectroscopy for decomposing CWD suggested further needs of its application to broad-leaved trees from tropical and subtropical regions.

  13. Metabolic pathways for ketone body production. /sup 13/C NMR spectroscopy of rat liver in vivo using /sup 13/C-multilabeled fatty acids

    Energy Technology Data Exchange (ETDEWEB)

    Pahl-Wostl, C.; Seelig, J.

    1986-11-04

    The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with /sup 13/C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of /sup 13/C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the /sup 13/C signal intensities were enhanced by using doubly labeled (1,3-/sup 13/C)butyrate as a substrate. Different /sup 13/C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The /sup 13/C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of /sup 13/C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded ..beta..-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. /sup 13/C-labeled glucose could be detected in vivo in the liver of diabetic rats.

  14. Characterization of alkyl carbon in forest soils by CPMAS 13C NMR spectroscopy and dipolar dephasing

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    Kogel-Knabner, I.; Hatcher, P.G.

    1989-01-01

    Samples obtained from forest soils at different stages of decomposition were treated sequentially with chloroform/methanol (extraction of lipids), sulfuric acid (hydrolysis), and sodium chlorite (delignification) to enrich them in refractory alkyl carbon. As revealed by NMR spectroscopy, this treatment yielded residues with high contents of alkyl carbon. In the NMR spectra of residues obtained from litter samples, resonances for carbohydrates are also present, indicating that these carbohydrates are tightly bound to the alkyl carbon structures. During decomposition in the soils this resistant carbohydrate fraction is lost almost completely. In the litter samples the alkyl carbon shows a dipolar dephasing behavior indicative of two structural components, a rigid and a more mobile component. As depth and decomposition increase, only the rigid component is observed. This fact could be due to selective degradation of the mobile component or to changes in molecular mobility during decomposition, e.g., because of an increase in cross linking or contact with the mineral matter of the soil.

  15. Differentiation of Histidine Tautomeric States using 15N Selectively Filtered 13C Solid-State NMR Spectroscopy

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    Miao, Yimin; Cross, Timothy A.; Fu, Riqiang

    2014-01-01

    The histidine imidazole ring in proteins usually contains a mixture of three possible tautomeric states (two neutral - τ and π states and a charged state) at physiological pHs. Differentiating the tautomeric states is critical for understanding how the histidine residue participates in many structurally and functionally important proteins. In this work, one dimensional 15N selectively filtered 13C solid-state NMR spectroscopy is proposed to differentiate histidine tautomeric states and to identify all 13C resonances of the individual imidazole rings in a mixture of tautomeric states. When 15N selective 180° pulses are applied to the protonated or non-protonated nitrogen region, the 13C sites that are bonded to the non-protonated or protonated nitrogen sites can be identified, respectively. A sample of 13C,15N labeled histidine powder lyophilized from a solution at pH 6.3 has been used to illustrate the usefulness of this scheme by uniquely assigning resonances of the neutral τ and charged states from the mixture. PMID:25026459

  16. Recent applications of /sup 13/C NMR spectroscopy to biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Matwiyoff, N.A.

    1981-01-01

    Carbon-13 nuclear magnetic resonance (NMR) spectroscopy, in conjunction with carbon-13 labelling, is a powerful new analytical technique for the study of metabolic pathways and structural components in intact organelles, cells, and tissues. The technique can provide, rapidly and non-destructively, unique information about: the architecture and dynamics of structural components; the nature of the intracellular environment; and metabolic pathways and relative fluxes of individual carbon atoms. With the aid of results recently obtained by us and those reported by a number of other laboratories, the problems and potentialities of the technique will be reviewed with emphasis on: the viscosities of intracellular fluids; the structure and dynamics of the components of membranes; and the primary and secondary metabolic pathways of carbon in microorganisms, plants, and mammalian cells in culture.

  17. Quality of spelt pasta enriched with eggs and identification of eggs using 13C MAS NMR spectroscopy

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    Filipović Jelena S.

    2015-01-01

    Full Text Available This paper deals with the characteristics of spelt pasta enriched with eggs. Eggs were added to spelt farina in the quantity of 0, 124 or 248 g/kg (equivalent to 0, 3 or 6 eggs, respectively. Post-hoc Tukey’s HSD test at 95% confidence limit showed significant differences between various samples. Relatively low coefficients of variation have been obtained for each applied assay (1.25-12.42%, which confirmed the high accuracy measurements and statistically significant results. Standard score analysis is applied for accessing the contribution of eggs content to spelt pasta quality. Maximum scores regarding quality (0.89 and chemical characteristics (0.70, have been obtained for 6 eggs spelt pasta formulation. It is also shown that the presence of eggs in pasta can be clearly confirmed by 13C MAS NMR spectroscopy. Simultaneous increase in area of peak positioned at 29.5 and 176 ppm is directly associated with the increase in the content of added eggs in the corresponding samples. Pertinent data point at positive contribution of eggs to the spelt pasta and also that NMR spectrum can be used in the egg quantity control. [Projekat Ministarstva nauke Republike Srbije, br. TRI 46005 i br. TR 31029

  18. Characterization of pyrogenic organic matter by 2-dimenstional HETeronucleus CORelation solid-state 13C NMR (HETCOR) spectroscopy

    Science.gov (United States)

    Knicker, Heike

    2016-04-01

    technique was used for monitoring the chemical changes occurring during charring of biomass derived from model compounds, fire-affected and unaffected NOM. The 2D 13C HETCOR NMR spectrum of the fire- unaffected soils revealed that most of the carboxyl C occurs as ester or amide. Aside from cross peaks typically seen in spectra of NOM, the spectrum of the respective fire-affected counterpart shows additional signals assignable to PyOM.

  19. Identification of Li-Ion Battery SEI Compounds through (7)Li and (13)C Solid-State MAS NMR Spectroscopy and MALDI-TOF Mass Spectrometry.

    Science.gov (United States)

    Huff, Laura A; Tavassol, Hadi; Esbenshade, Jennifer L; Xing, Wenting; Chiang, Yet-Ming; Gewirth, Andrew A

    2016-01-13

    Solid-state (7)Li and (13)C MAS NMR spectra of cycled graphitic Li-ion anodes demonstrate SEI compound formation upon lithiation that is followed by changes in the SEI upon delithiation. Solid-state (13)C DPMAS NMR shows changes in peaks associated with organic solvent compounds (ethylene carbonate and dimethyl carbonate, EC/DMC) upon electrochemical cycling due to the formation of and subsequent changes in the SEI compounds. Solid-state (13)C NMR spin-lattice (T1) relaxation time measurements of lithiated Li-ion anodes and reference poly(ethylene oxide) (PEO) powders, along with MALDI-TOF mass spectrometry results, indicate that large-molecular-weight polymers are formed in the SEI layers of the discharged anodes. MALDI-TOF MS and NMR spectroscopy results additionally indicate that delithiated anodes exhibit a larger number of SEI products than is found in lithiated anodes. PMID:26653886

  20. Unilateral NMR, 13C CPMAS NMR spectroscopy and micro-analytical techniques for studying the materials and state of conservation of an ancient Egyptian wooden sarcophagus.

    Science.gov (United States)

    Proietti, Noemi; Presciutti, Federica; Di Tullio, Valeria; Doherty, Brenda; Marinelli, Anna Maria; Provinciali, Barbara; Macchioni, Nicola; Capitani, Donatella; Miliani, Costanza

    2011-03-01

    A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV-XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix. This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood and the presence of organic substances by (13)C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical microscopy (OM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Raman and surface enhanced (resonance) Raman spectroscopy (SERS/SERRS), infrared and GC-MS techniques, evidencing original components such as clay minerals, Egyptian green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy.

  1. Chemical structures of swine-manure chars produced under different carbonization conditions investigated by advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy

    Science.gov (United States)

    Two types of swine manure chars, hydrothermally-produced hydrochar and slow-pyrolysis pyrochar, and their raw swine manure solid were characterized using advanced 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. Compared with the parent raw swine manure, both hydrochars and pyrochar di...

  2. Conformation and dynamics of melittin bound to magnetically oriented lipid bilayers by solid-state (31)P and (13)C NMR spectroscopy.

    OpenAIRE

    Naito, A.; T. Nagao; Norisada, K; Mizuno, T; Tuzi, S.; Saitô, H.

    2000-01-01

    The conformation and dynamics of melittin bound to the dimyristoylphosphatidylcholine (DMPC) bilayer and the magnetic orientation in the lipid bilayer systems were investigated by solid-state (31)P and (13)C NMR spectroscopy. Using (31)P NMR, it was found that melittin-lipid bilayers form magnetically oriented elongated vesicles with the long axis parallel to the magnetic field above the liquid crystalline-gel phase transition temperature (T(m) = 24 degrees C). The conformation, orientation, ...

  3. Determination of the structural changes by Raman and 13C CP/MAS NMR spectroscopy on native corn starch with plasticizers

    International Nuclear Information System (INIS)

    The plasticizing - antiplasticizing effect of water and glycerol contents on native corn starch samples is investigated by FT-Raman and 13C CP/MAS NMR spectroscopy. The presence of both amorphous and crystalline structural phases was evidenced in pure native corn starch and also in the samples containing plasticizers. Among the crystalline starch structures, the A- and V- types were suggested by CP/MAS NMR spectra

  4. Oxidative stress-induced metabolic changes in mouse C2C12 myotubes studied with high-resolution 13C, 1H, and 31P NMR spectroscopy

    DEFF Research Database (Denmark)

    Straadt, Ida K; Young, Jette F; Petersen, Bent O;

    2010-01-01

    In this study, stress in relation to slaughter was investigated in a model system by the use of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy for elucidating changes in the metabolites in C2C12 myotubes exposed to H(2)O(2)-induced stress. Oxidative stress resulted in lower...... to lower levels of the unlabeled ((12)C) lactate were identified in the (1)H spectra after stress exposure. These data indicate an increase in de novo synthesis of alanine, concomitant with a release of lactate from the myotubes to the medium at oxidative stress conditions. The changes in the metabolite...... levels of several metabolites, mainly amino acids; however, higher levels of alanine were apparent in the (13)C spectra after incubation with [(13)C(1)]glucose. In the (13)C spectra [(13)C(3)]lactate tended to increase after exposure to increasing concentrations of H(2)O(2); conversely, a tendency...

  5. A simple mathematical model and practical approach for evaluating citric acid cycle fluxes in perfused rat hearts by 13C-NMR and 1H-NMR spectroscopy.

    Science.gov (United States)

    Tran-Dinh, S; Hoerter, J A; Mateo, P; Bouet, F; Herve, M

    1997-04-15

    We propose a simple mathematical model and a practical approach for evaluating the flux constant and the absolute value of flux in the citric acid cycle in perfused organs by 13C-NMR and 1H-NMR spectroscopy. We demonstrate that 13C-NMR glutamate spectra are independent of the relative sizes of the mitochondrial and cytosolic compartments and the exchange rates of glutamates, unless there is a difference in 13C chemical shifts of glutamate carbons between the two compartments. Wistar rat hearts (five beating and four KCl-arrested hearts) were aerobically perfused with 100% enriched [2-(13)C]acetate and the kinetics of glutamate carbon labeling from perchloric acid extracts were studied at various perfusion times. Under our experimental conditions, the citric acid cycle flux constant, which represents the fraction of glutamate in exchange with the citric acid cycle per unit time, is about 0.350 +/- 0.003 min(-1) for beating hearts and 0.0741 +/- 0.004 min(-1) for KCl-arrested hearts. The absolute values of the citric acid flux for beating hearts and for KCl-arrested hearts are 1.06 +/- 0.06 micromol x min(-1) x mg(-1) and 0.21 +/- 0.02 micromol x min(-1) x g(-1), respectively. The fraction of unlabeled acetate determined from the proton signal of the methyl group is small and essentially the same in beating and arrested hearts (7.4 +/- 1.7% and 8.8 +/- 2.1%, respectively). Thus, the large difference in the Glu C2/C4 between beating and arrested hearts is not due to the important contribution from anaplerotic sources in arrested hearts but simply to a substantial difference in citric acid cycle fluxes. Our model fits the experimental data well, indicating a fast exchange between 2-oxoglutarate and glutamate in the mitochondria of rat hearts. Analysis of the flux constant, calculated from the half-time of glutamate C4 labeling given in the literature, allows for a comparison of the citric acid flux for various working conditions in different animal species.

  6. Chemical composition of the essential oil from Corsican Mentha aquatica--combined analysis by GC(RI), GC-MS and 13C NMR spectroscopy.

    Science.gov (United States)

    Sutour, Sylvain; Tomi, Félix; Bradesi, Pascale; Casanova, Joseph

    2011-10-01

    The essential oil (EO) of M. aquatica L. growing wild in Corsica was isolated by dry vapor distillation and submitted to combined analysis by column chromatography over silica gel, GC(RI), GC-MS and 13C NMR spectroscopy. The composition was dominated byoxygenated monoterpenes and characterized by the occurrence of menthofuran (50.7%) as the major component. In parallel, seven laboratory-distilled oil samples isolated from individual plants collected in Corsica were analyzed by GC(RI) and 13C NMR spectroscopy. Onlyquantitative differences were observed between the samples. Beside the usual terpenes, various p-menthane lactones (mintlactone, isomintlactone, hydroxymintlactone, menthofurolactone and epimenthofurolactone) have been identified in all the oil samples.

  7. High-resolution solid-state 13C NMR spectroscopy of the paramagnetic metal-organic frameworks, STAM-1 and HKUST-1.

    Science.gov (United States)

    Dawson, Daniel M; Jamieson, Lauren E; Mohideen, M Infas H; McKinlay, Alistair C; Smellie, Iain A; Cadou, Romain; Keddie, Neil S; Morris, Russell E; Ashbrook, Sharon E

    2013-01-21

    Solid-state (13)C magic-angle spinning (MAS) NMR spectroscopy is used to investigate the structure of the Cu(II)-based metal-organic frameworks (MOFs), HKUST-1 and STAM-1, and the structural changes occurring within these MOFs upon activation (dehydration). NMR spectroscopy is an attractive technique for the investigation of these materials, owing to its high sensitivity to local structure, without any requirement for longer-range order. However, interactions between nuclei and unpaired electrons in paramagnetic systems (e.g., Cu(II)-based MOFs) pose a considerable challenge, not only for spectral acquisition, but also in the assignment and interpretation of the spectral resonances. Here, we exploit the rapid T(1) relaxation of these materials to obtain (13)C NMR spectra using a spin-echo pulse sequence at natural abundance levels, and employ frequency-stepped acquisition to ensure uniform excitation of resonances over a wide frequency range. We then utilise selective (13)C isotopic labelling of the organic linker molecules to enable an unambiguous assignment of NMR spectra of both MOFs for the first time. We show that the monomethylated linker can be recovered from STAM-1 intact, demonstrating not only the interesting use of this MOF as a protecting group, but also the ability (for both STAM-1 and HKUST-1) to recover isotopically-enriched linkers, thereby reducing significantly the overall cost of the approach.

  8. Direct one step preparation and 13 C-NMR spectroscopy characterization of α-ferrocenyl carbocations derived from ferrocene and carbonyl compounds in trifluoroacetic acid medium1a

    International Nuclear Information System (INIS)

    Reactions of aldehydes and ketones with ferrocene, in the presence of trifluoroacetic acid, afforded a series of stable long lived αferrocenylalkyl carbocations which were characterized by 13 C-NMR spectroscopy. When this reactions was attempted using tetraphenyl cyclopentadienone quite unexpectedly corresponding dihydro derivative 3 was isolated, in very good yield. Formation of this compound may require ferrocene acting as a reducing agent. (author)

  9. Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

    Science.gov (United States)

    Duarte, João M N; Gruetter, Rolf

    2013-09-01

    Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13)C incorporation into brain metabolites by dynamic (13)C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13)C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. PMID:23745684

  10. The 'Nuts and Bolts' of 13C NMR Spectroscopy at Elevated-Pressures and -Temperatures for Monitoring In Situ CO2 Conversion to Metal Carbonates

    Science.gov (United States)

    Moore, J. K.; Surface, J. A.; Skemer, P. A.; Conradi, M. S.; Hayes, S. E.

    2013-12-01

    characterization of multiple metastable mineral phases in pure forms and in mixtures. Notably, NMR spectroscopy is able to observe signals from amorphous materials, and mixtures of both crystalline and amorphous species can be analyzed. NMR results are verified through a combination of Raman spectroscopy and powder XRD (of crystalline species). Further, we have examined the effects on mineralization reactions of pH gradients in the sample--also monitored in situ by NMR--and these results will be presented. Reference: 'In Situ Measurement of Magnesium Carbonate Formation from CO2 Using Static High-Pressure and -Temperature 13C NMR' J. Andrew Surface, Philip Skemer, Sophia E. Hayes, and Mark S. Conradi, Environ. Sci. Technol. 2013, 47, 119-125. DOI: 10.1021/es301287n

  11. Soil nitrogen mineralisation and organic matter composition revealed by 13C NMR spectroscopy under repeated prescribed burning in eucalypt forests of south-east Queensland

    International Nuclear Information System (INIS)

    The effects of burning on in situ extractable nitrogen (NH+4-N+NO-3-N) and net N mineralisation following scheduled fuel reduction burns in repeatedly burnt dry and wet sclerophyll forest sites in south-east Queensland were assessed. In addition, soil organic matter composition in the wet sclerophyll site was assessed by 13C NMR spectroscopy. The results showed that at the dry sclerophyll site, extractable N and net N mineralisation for 1 year were largely unaffected by burning, while at the wet sclerophyll site, these parameters decreased. 13C NMR analysis of soil samples from the wet sclerophyll site revealed that there was a significant reduction in the proportion of O-alkyl (alkoxy/carbohydrate) C with increasing burning frequency. Statistically significant effects on the other chemical shift regions were not detected. The ratio of alkyl C to O-alkyl C, a proposed index of organic matter decomposition, increased with increasing burning frequency. A high ratio of alkyl C to O-alkyl C suggests low amounts of carbohydrates relative to waxes and cutins, which could in turn lead to slower mineralisation. The findings are in accord with this hypothesis. There were significant linear relationships between cumulative N mineralisation for 1 year and the proportions of alkyl C and O-alkyl C, and the ratio of alkyl C/O-alkyl C. Thus, in addition to reductions in substrate quantity (low organic C and total N for burnt soils), there was also an alteration of substrate quality as revealed by 13C NMR spectroscopy which is reflected in low N mineralisation. Copyright (1999) CSIRO Publishing

  12. 13C-Labeled Heparan Sulfate Analogue as a Tool To Study Protein/Heparan Sulfate Interactions by NMR Spectroscopy: Application to the CXCL12α Chemokine

    International Nuclear Information System (INIS)

    Heparan sulfate (HS), a polysaccharide of the glycosaminoglycan family characterized by a unique level of complexity, has emerged as a key regulator of many fundamental biological processes. Although it has become clear that this class of molecules exert their functions by interacting with proteins, the exact modes of interaction still remain largely unknown. Here we report the engineering of a 13C-labeled HS-like oligosaccharide with a defined oligo-saccharidic sequence that was used to investigate the structural determinants involved in protein/HS recognition by multidimensional NMR spectroscopy. Using the chemokine CXCL12α as a model system, we obtained experimental NMR data on both the oligosaccharide and the chemokine that was used to obtain a structural model of a protein/HS complex. This new approach provides a foundation for further investigations of protein/HS interactions and should find wide application. (authors)

  13. Calculation of average molecular parameters, functional groups, and a surrogate molecule for heavy fuel oils using 1H and 13C NMR spectroscopy

    KAUST Repository

    Abdul Jameel, Abdul Gani

    2016-04-22

    Heavy fuel oil (HFO) is primarily used as fuel in marine engines and in boilers to generate electricity. Nuclear Magnetic Resonance (NMR) is a powerful analytical tool for structure elucidation and in this study, 1H NMR and 13C NMR spectroscopy were used for the structural characterization of 2 HFO samples. The NMR data was combined with elemental analysis and average molecular weight to quantify average molecular parameters (AMPs), such as the number of paraffinic carbons, naphthenic carbons, aromatic hydrogens, olefinic hydrogens, etc. in the HFO samples. Recent formulae published in the literature were used for calculating various derived AMPs like aromaticity factor 〖(f〗_a), C/H ratio, average paraffinic chain length (¯n), naphthenic ring number 〖(R〗_N), aromatic ring number〖 (R〗_A), total ring number〖 (R〗_T), aromatic condensation index (φ) and aromatic condensation degree (Ω). These derived AMPs help in understanding the overall structure of the fuel. A total of 19 functional groups were defined to represent the HFO samples, and their respective concentrations were calculated by formulating balance equations that equate the concentration of the functional groups with the concentration of the AMPs. Heteroatoms like sulfur, nitrogen, and oxygen were also included in the functional groups. Surrogate molecules were finally constructed to represent the average structure of the molecules present in the HFO samples. This surrogate molecule can be used for property estimation of the HFO samples and also serve as a surrogate to represent the molecular structure for use in kinetic studies.

  14. Magnetic resonance spectroscopy and metabolism. Applications of proton and 13C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo.

    Science.gov (United States)

    Portais, J C; Pianet, I; Allard, M; Merle, M; Raffard, G; Kien, P; Biran, M; Labouesse, J; Caille, J M; Canioni, P

    1991-01-01

    Nuclear magnetic resonance (NMR) spectroscopy was used to study the metabolism of cells from the central nervous system both in vitro on perchloric acid extracts obtained either from cultured tumoral cells (C6 rat glioma) or rat astrocytes in primary culture, and in vivo within the human brain. Analysis of carbon 13 NMR spectra of perchloric acid extracts prepared from cultured cells in the presence of NMR [1-13C] glucose as substrate allowed determination of the glutamate and glutamine enrichments in both normal and tumoral cells. Preliminary results indicated large changes in the metabolism of these amino acids (and also of aspartate and alanine) in the C6 cell as compared to its normal counterpart. Localized proton NMR spectra of the human brain in vivo were obtained at 1.5 T, in order to evaluate the content of various metabolites, including glutamate, in peritumoral edema from a selected volume of 2 x 2 x 2 cm3. N-acetyl aspartate, glutamate, phosphocreatine, creatine, choline and inositol derivative resonances were observed in 15 min spectra. N-acetyl-aspartate was found to be at a lower level in contrast to glutamate which was detected at a higher level in the injured area as compared to the contralateral unaffected side. PMID:1674432

  15. Magnetic resonance spectroscopy and metabolism. Applications of proton and sup 13 C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Portais, J.C.; Pianet, I.; Merle, M.; Raffard, G.; Biran, M.; Labouesse, J.; Canioni, P. (Bordeaux-2 Univ., 33 (FR)); Allard, M.; Kien, P.; Caille, J.M. (Centre Hospitalier Universitaire, 33 Bordeaux (FR))

    1991-01-01

    Nuclear magnetic resonance (NMR) spectroscopy was used to study the metabolism of cells from the central nervous system both in vitro on perchloric acid extracts obtained either from cultured tumoral cells (C6 rat glioma) or rat astrocytes in primary culture, and in vivo within the human brain. Analysis of carbon 13 NMR spectra of perchloric acid extracts prepared from cultured cells in the presence of NMR (1-{sup 13}C) glucose as substrate allowed determination of the glutamate and glutamine enrichments in both normal and tumoral cells. Preliminary results indicated large changes in the metabolism of these amino acids (and also of aspartate and alanine) in the C6 cell as compared to its normal counterpart. Localized proton NMR spectra of the human brain in vivo were obtained at 1.5 T, in order to evaluate the content of various metabolites, including glutamate, in peritumoral edema from a selected volume of 2 x 2 x 2 cm{sup 3}. N-acetyl aspartate, glutamate, phosphocreatine, creatine, choline and inositol derivative resonances were observed in 15 min spectra. N-acetyl-aspartate was found to be at a lower level in contrast to glutamate which was detected at a higher level in the injured area as compared to the controlateral unaffected side.

  16. Kinetic analysis of reactions of Si-based epoxy resins by near-infrared spectroscopy, {sup 13}C NMR and soft-hard modelling

    Energy Technology Data Exchange (ETDEWEB)

    Garrido, Mariano [Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.li Domingo s/n, 43007 Tarragona (Spain); Larrechi, Maria Soledad [Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.li Domingo s/n, 43007 Tarragona (Spain)]. E-mail: mariasoledad.larrechi@urv.cat; Rius, F. Xavier [Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.li Domingo s/n, 43007 Tarragona (Spain); Mercado, Luis Adolfo [Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.li Domingo s/n, 43007 Tarragona (Spain); Galia, Marina [Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.li Domingo s/n, 43007 Tarragona (Spain)]. E-mail: marina.galia@urv.cat

    2007-02-05

    Soft- and hard-modelling strategy was applied to near-infrared spectroscopy data obtained from monitoring the reaction between glycidyloxydimethylphenyl silane, a silicon-based epoxy monomer, and aniline. On the basis of the pure soft-modelling approach and previous chemical knowledge, a kinetic model for the reaction was proposed. Then, multivariate curve resolution-alternating least squares optimization was carried out under a hard constraint, that compels the concentration profiles to fulfil the proposed kinetic model at each iteration of the optimization process. In this way, the concentration profiles of each species and the corresponding kinetic rate constants of the reaction, unpublished until now, were obtained. The results obtained were contrasted with {sup 13}C NMR. The joint interval test of slope and intercept for detecting bias was not significant ({alpha} = 5%)

  17. Characterization of the humic substances isolated from postfire soils of scotch pine forest in Togljatty city, Samara region by the 13C-NMR spectroscopy

    Science.gov (United States)

    Maksimova, Ekaterina; Abakumov, Evgeny

    2016-04-01

    Postpyrogenic soil dynamics is an informative tool for studying of soil elementary processes in extreme temperature conditions and for predicting of short time environmental changes in conditions of catastrophic landscape changes. Soil organic matter (SOM) system evolution is the most rapid process of postpyrogenic soil development. In this relation the evaluation of humus accumulation rates and humification trend were conducted with use of the classical chemical and modern spectroscopy methods. Soil restoration after spontaneous forest fires near Togljatty city (Samara region, Russia) was abandoned in 2010, and further monitoring over the next four years was organized to evaluate the speed of biogenic processes and humus accumulation dynamics. Three key soil plots were studied for estimating SOM quality changes under the forest fire effect: surface forest fire, crown forest fire and control. Total carbon and nitrogen content as well as Cha/Cfa ratios (content of humic acids/ content of fulvic acids), were estimated to assess the dynamics of soil restoration. Humic acid powders were extracted and analyzed by elemental composition and 13C-NMR spectroscopy to assess changes in humic substance structure and composition. The data obtained indicate that burning of a forest floor and sod (humic) horizon led to humus losses and decreases in total carbon stocks. As a result of the fires, the content of humic acids in the pyrogenic horizon increased, leading alterations of humus type. Greater increases in the degree of organic matter humification were observed for surface fires than crown fires. It was shown that the humus molecular composition was substantially affected by the wildfires. The data show an increase in aromaticity, a loss of oxygen-containing groups and dehydrogenation of humic acids. Humic acids in the soils of the control plots and after wildfires were significantly different, especially in the ratios of hydrogen, oxygen and carbon. The increase in the

  18. Functional Groups Determine Biochar Properties (pH and EC as Studied by Two-Dimensional (13C NMR Correlation Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Xiaoming Li

    Full Text Available While the properties of biochar are closely related to its functional groups, it is unclear under what conditions biochar develops its properties. In this study, two-dimensional (2D (13C nuclear magnetic resonance (NMR correlation spectroscopy was for the first time applied to investigate the development of functional groups and establish their relationship with biochar properties. The results showed that the agricultural biomass carbonized to biochars was a dehydroxylation/dehydrogenation and aromatization process, mainly involving the cleavage of O-alkylated carbons and anomeric O-C-O carbons in addition to the production of fused-ring aromatic structures and aromatic C-O groups. With increasing charring temperature, the mass cleavage of O-alkylated groups and anomeric O-C-O carbons occurred prior to the production of fused-ring aromatic structures. The regression analysis between functional groups and biochar properties (pH and electrical conductivity further demonstrated that the pH and electrical conductivity of rice straw derived biochars were mainly determined by fused-ring aromatic structures and anomeric O-C-O carbons, but the pH of rice bran derived biochars was determined by both fused-ring aromatic structures and aliphatic O-alkylated (HCOH carbons. In summary, this work suggests a novel tool for characterising the development of functional groups in biochars.

  19. Forms of organic C and P extracted from tropical soils as assessed by liquid-state 13C- and 31P-NMR spectroscopy

    International Nuclear Information System (INIS)

    Transformation of soil organic phosphorus (SOP) is linked with the transformation of soil organic carbon (SOC). Yet, it is uncertain to which SOC structures the cycling of SOP is related, especially in tropical environments. To clarify this issue, we determined the vertical distribution of extractable C and P chemical structures in 4 soil profiles using solution 13C- and 31P-nuclear magnetic resonance (NMR) spectroscopy after extraction with 0.1 M NaOH/0.4 M NaF (1 : 1). Soils were from a cabbage cultivation with annual burning of weeds, a Pinus reforestation, a secondary forest, and a primary forest in northern Thailand. For all profiles, signals due to O-alkyl and carbonyl C dominated the 13C-NMR spectra (up to 50 and 22% of total spectral area, respectively). The proportions of alkyl and aryl C decreased, whereas carbonyl and O-alkyl C increased with soil depth. Sharp resonances at 135 and 177 ppm appeared in spectra of subsoil horizons. They indicated mellitic acid, an end-product of the oxidation of charred plant residues. The SOP forms comprised mainly orthophosphate diesters in the organic layer of the forests, whereas in the mineral horizons orthophosphate monoesters dominated the chemical composition of extractable SOP. The relationships between SOC and SOP forms in the organic floor layers of the forests were clearly different from those in the mineral soil horizons, indicating changed SOM dynamics upon contact with soil minerals. In the forest mineral soils, significant correlations between monoester-P and O-alkyl C (R = 0.84, P < 0.001) were found. Diester-P, teichoic acids, and phosphonates were positively correlated with aromatic C and negatively with O-alkyl C. At the same time, teichoic acids and phosphonates were positively correlated with short range-ordered Al and Fe oxide phases. These findings can be explained through an increasing microbial decay of aryl C and diester-P compounds that may be less effectively stabilised at lower depths

  20. Direct 13C NMR Detection in HPLC Hyphenation Mode

    DEFF Research Database (Denmark)

    Wubshet, Sileshi Gizachew; Johansen, Kenneth; Nyberg, Nils;

    2012-01-01

    Solid phase extraction (SPE) was introduced as a crucial step in the HPLC-SPE-NMR technique to enable online analyte enrichment from which proton-detected NMR experiments on submicrogram amounts from complex mixtures were possible. However, the significance of direct-detected (13)C NMR experiments...... application of HPLC-SPE-NMR analysis using direct-detected (13)C NMR spectra. HPLC column loading, accumulative SPE trappings, and the effect of different elution solvents were evaluated and optimized. A column loading of approximately 600 mug of a prefractionated triterpenoid mixture, six trappings...

  1. Dihydroflavanonols from Cedrus deodara, A (13)C NMR study.

    Science.gov (United States)

    Agrawal, P K; Agarwal, S K; Rastogi, R P; Osterdahal, B G

    1981-09-01

    High resolution (13)C NMR study of taxifolin, cedeodarin, cedrin and their methyl ethers allowed unambiguous placement of the Me in 5,7-dihydroxyflavanonol nucleus, besides providing other valuable information on the substitution pattern in the molecule.

  2. Dynamics of the carbohydrate chains attached to the Fc portion of immunoglobulin G as studied by NMR spectroscopy assisted by selective 13C labeling of the glycans

    International Nuclear Information System (INIS)

    A systematic method for 13C labeling of the glycan of immunoglobulin G for NMR study has been developed. A mouse immunoglobulin of subclass IgG2b has been used for the experiment. On the basis of chemical shift and linewidth data, it has been concluded that (1) the mobility of the carbohydrate chain in IgG2b is comparable to that of the backbone polypeptide chain with the exception of the galactose residue at the nonreducing end of the Manα1-3 branch, which is extremely mobile and (2) agalactosylation does not induce any significant change in the mobility. The results obtained indicate that even in the agalactosyl form the glycans are buried in the protein. Biological significance of the NMR results obtained is also briefly discussed

  3. Porcine cytosolic aspartate aminotransferase reconstituted with (4 prime - sup 13 C)pyridoxal phosphate. pH- and ligand-induced changes of the coenzyme observed by sup 13 C NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Higaki, Tsuyoshi (Kumamoto Univ. College of Medical Science (Japan) Kumamoto Univ. Medical School (Japan)); Tanase, Sumio; Nagashima, Fujio; Morino, Yoshimasa (Kumamoto Univ. Medical School (Japan)); Scott, A.I.; Williams, H.J.; Stolowich, N.J. (Texas A and M Univ., College Station (United States))

    1991-03-05

    Apoenzyme samples of aspartate aminotransferase (AspAT) purified from the cytosolic fraction of pig heart were reconstituted with (4{prime}-{sup 13}C)pyridoxal 5{prime}-phosphate (pyridoxal-P). The {sup 13}C NMR spectra of AspAT samples thus generated established the chemical shift of 165.3 ppm for C4{prime} of the coenzyme bound as an internal aldimine with lysine 258 of the enzyme at pH 5. In the absence of ligands the chemical shift of C4{prime} was shown to be pH dependent, shifting 5 ppm upfield to a constant value of 160.2 ppm above pH 8, the resulting pK{sub a} of 6.3 in agreement with spectrophotometric titrations. The addition of the competitive inhibitor succinate to the internal aldimine raises the pK{sub a} of the imine to 7.8, consistent with the theory of charge neutralization in the active site. In the presence of saturating concentrations of 2-methylaspartic acid the C4{prime} signal of the coenzyme was shown to be invariant with pH and located at 162.7 ppm, midway between the observed chemical shifts of the protonated and unprotonated forms of the internal aldimine. Finally, the line widths of the C4{prime} resonance under the various conditions were measured and qualitatively compared. The results are discussed in terms of the current mechanism and molecular models of the active site of AspAT.

  4. Mathematical models for determining metabolic fluxes through the citric acid and the glyoxylate cycles in Saccharomyces cerevisiae by 13C-NMR spectroscopy.

    Science.gov (United States)

    Tran-Dinh, S; Bouet, F; Huynh, Q T; Herve, M

    1996-12-15

    We propose, first, a practical method for studying the isotopic transformation of glutamate or any other metabolite isotopomers in the citric acid and the glyoxylate cycles; second, two mathematical models, one for evaluating the flux through the citric acid cycle and the other for evaluating the flux through the latter coupled to the glyoxylate cycle in yeast. These models are based on the analysis of 13C-NMR spectra of glutamate obtained from Saccharomyces cerevisiae, NCYC strain, fed with 100% enriched [2-13C]acetate. The population of each glutamate isotopomer, the change in intensity of each multiplet component or the enrichment of any glutamate carbon is expressed by a specific analytical equation from which the flux in the citric acid and the glyoxylate cycles can be deduced. The aerobic metabolism of 100% [2-13C]acetate in acetate-grown S. cerevisiae cells was studied as a function of time using 13C-NMR. 1H-NMR and biochemical techniques. The C1 and C6 doublet and singlet of labeled trehalose increase continuously with time indicating that there is no isotopic transformation between trehalose isotopomers even though the corresponding formation rates are different. By contrast, the glutamate C4 singlet increases then decreases with time. The C4 doublet, which is lower than the singlet for t 90 min. A similar observation was made for the C2 resonance singlet and doublet. In addition, the glutamate C2 multiplet consists of only seven instead of nine peaks as in random labeling. These results agree well with our models and demonstrate that, in the presence of acetate, anaplerotic carbon sources involved in the synthesis of acetyl-CoA are negligible in yeast. The flux in the citric acid cycle was deduced from a plot of the C4 area versus incubation time, while the flux within the glyoxylate cycle was determined from the relative intensity of the glutamate C4 doublet and singlet. The fluxes in the citric acid and the glyoxylate cycles were found to be comparable

  5. Short hydrogen bonds in salts of dicarboxylic acids; structural correlations from solid-state 13C and 2H NMR spectroscopy

    Science.gov (United States)

    Kalsbeek, Nicoline; Schaumburg, Kjeld; Larsen, Sine

    1993-10-01

    Solid-state 13C and 2H NMR spectra are found to very suitable for characterizing the short Osbnd H...O hydrogen bonds observed in acid salts of dicarboxylic acids. The majority of the investigated compounds are acid salts of malonic, succinic and tartaric acid with monovalent cations derived from alkali metals and small aliphatic amines. They include systems with symmetric and asymmetric hydrogen bonds. Accurate structural information about their geometry is available from low-temperature X-ray diffraction data. The 13C chemical shifts of the C atoms in the different carboxy groups display a linear variation with the absolute difference between the two Csbnd O bond lengths. Theoretical ab initio calculations for model systems showed that the nuclear quadrupole coupling constant NQCC for 2H increases with increasing asymmetry of the hydrogen-bonded system. NQCC values for 2H in the short symmetric hydrogen-bonded systems are in the range 53-59 kHz compared with the larger values of up to 166kHz found in systems with longer asymmetric hydrogen bonds. The 2H NQCC values display a perfect linear dependence on the asymmetry of the hydrogen bond. 2H NQCC decreases with decreasing temperature in the symmetric hydrogen bonds showing that the corresponding potential has a single well.

  6. Carbonation of C–S–H and C–A–S–H samples studied by {sup 13}C, {sup 27}Al and {sup 29}Si MAS NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sevelsted, Tine F.; Skibsted, Jørgen, E-mail: jskib@chem.au.dk

    2015-05-15

    Synthesized calcium silicate hydrate (C–S–H) samples with Ca/Si ratios of 0.66, 1.0, and 1.5 have been exposed to atmospheric CO{sub 2} at room temperature and high relative humidity and studied after one to 12 weeks. {sup 29}Si NMR reveals that the decomposition of C–S–H caused by carbonation involves two steps and that the decomposition rate decreases with increasing Ca/Si ratio. The first step is a gradual decalcification of the C–S–H where calcium is removed from the interlayer and defect sites in the silicate chains until Ca/Si = 0.67 is reached, ideally corresponding to infinite silicate chains. In the seconds step, calcium from the principal layers is consumed, resulting in the final decomposition of the C–S–H and the formation of an amorphous silica phase composed of Q{sup 3} and Q{sup 4} silicate tetrahedra. The amount of solid carbonates and of carbonate ions in a hydrous environment increases with increasing Ca/Si ratio for the C–S–H, as shown by {sup 13}C NMR. For C–A–S–H samples with Ca/Si = 1.0 and 1.5, {sup 27}Al NMR demonstrates that all aluminium sites associated with the C–S–H are consumed during the carbonation reactions and incorporated mainly as tetrahedral Al(–OSi){sub 4} units in the amorphous silica phase. A small amount of penta-coordinated Al sites has also been identified in the silica phase.

  7. /sup 13/C-NMR of diterpenes with rosane skeleton

    Energy Technology Data Exchange (ETDEWEB)

    da Cunha Pinto, A.; Garcez, W.S.; Ficara, M.L.G.; Vasconcelos, T.C.; Pereira, A.L.; Gomes, L.N.L.F.; Frechiani, M.doC.; Patitucci, M.L. (Rio de Janeiro Univ. (Brazil). Nucleo de Pesquisas de Produtos Naturais)

    1982-03-01

    /sup 13/C-NMR data of three diterpenoids with rosane skeleton isolated from Vellozia candida Mikan, and of their oxidated and acetylated derivatives are presented. The main effects caused by small structural differences are discussed and used in the assignment of the chemical shifts of all carbons.

  8. Solid state 13C NMR analysis of Brazilian cretaceous ambers

    International Nuclear Information System (INIS)

    13C cross polarization with magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectra have been obtained for the first time to three Cretaceous amber samples from South America. The samples were dated to Lower Cretaceous and collected in sediments from the Amazonas, Araripe and Reconcavo basins, Brazil. All samples have very similar spectra, consistent with a common paleobotanical source. Some aspects of the spectra suggest a relationship between Brazilian ambers and Araucariaceae family, such as intense resonances at 38-39 ppm. All samples are constituted by polylabdane structure associated to Class Ib resins, constituted by polymers of labdanoid diterpenes. Finally, information concerning some structural changes during maturation, such as isomerization of Δ8(17) and Δ12(13) unsaturations, were obtained by 13C NMR analyses. The results concerning botanical affinities are in accordance with previous results obtained by gas chromatography-mass spectrometry (GC-MS). (author)

  9. Mathematical model for evaluating the Krebs cycle flux with non-constant glutamate-pool size by 13C-NMR spectroscopy. Evidence for the existence of two types of Krebs cycles in cells.

    Science.gov (United States)

    Tran-Dinh, S; Beganton, F; Nguyen, T T; Bouet, F; Herve, M

    1996-12-01

    A practical method using matrix operations is proposed for studying the isotopic transformation of glutamate, or any other metabolite isotopomers, in the Krebs cycle. Two mathematical models were constructed for evaluating the Krebs cycle flux where the enrichment of [2-13C]acetyl-CoA is not 100% and the total glutamate concentration remains constant or varies during incubation. A comparative study of [1-13C]glucose metabolism was subsequently carried out using Saccharomyces cerevisiae cells from two different strains (ATCC-9763 and NCYC-239) by 13C-NMR spectroscopy and biochemical techniques. The results show that there are two types of Krebs cycles in cells. The first is represented by the ATCC cells which contain a small amount of 2-oxoglutarate dehydrogenase and hence the flux in the Krebs cycle is negligible. With [1-13C]glucose as a carbon source, the 13C-NMR spectra of glutamate exhibit the C2 and C4 resonances that are almost equivalent and much greater than that of the C3. Labeled metabolites derived from [1-13C]glucose enter the Krebs cycle at two points: oxaloacetate and citrate. The second cell type is represented by NCYC-239. The C2 and C3 areas are equivalent and smaller than the C4 resonance. The results suggest that labeled metabolites enter the Krebs cycle only at the citrate level via acetyl-CoA, 2-oxoglutarate dehydrogenase is present but pyruvate carboxylase is virtually absent or inactivated. When both are incubated with glucose, the total concentration of glutamate was found to decrease with the incubation time. The fraction of glutamate in isotopic exchange with the Krebs cycle in NCYC-239 cells is about 2.6% and the reduction in glutamate concentration is about 0.5%/min. Using our model, with a variable glutamate pool size, good agreement between the theoretical and experimental data is obtained.

  10. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    Science.gov (United States)

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.

    1998-02-01

    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  11. Elucidating the guest-host interactions and complex formation of praziquantel and cyclodextrin derivatives by (13)C and (15)N solid-state NMR spectroscopy.

    Science.gov (United States)

    Arrúa, Eva C; Ferreira, M João G; Salomon, Claudio J; Nunes, Teresa G

    2015-12-30

    Praziquantel is the drug of choice to treat several parasitic infections including the neglected tropical disease schistosomiasis. Due to its low aqueous solubility, cyclodextrins have been tested as potential host candidates to prepare praziquantel inclusion complexes with improved solubility. For the first time, the interactions of praziquantel with β-cyclodextrin and β-cyclodextrin derivatives (methyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin) were investigated using high resolution solid-state NMR spectroscopy. The results of this work confirmed that solid-state NMR experiments provided structural characterization, demonstrating the formation of inclusion complexes most probably with PZQ adopting an anti conformation, also the most likely in amorphous raw PZQ. Further information on the interaction of praziquantel with methyl-β-cyclodextrin was obtained from proton rotating-frame relaxation time measurements, sensitive to kilohertz-regime motions but modulated by spin-diffusion. Evidences were presented in all cases for praziquantel complexation through the aromatic ring. In addition, 1:2 drug:carrier molar ratio appears to be the most probable and therefore suitable stoichiometry to improve pharmaceutical formulations of this antischistosomal drug. PMID:26602291

  12. Characterization of polysulfone and polysulfone/vanillin microcapsules by 1H NMR spectroscopy, solid-state 13C CP/MAS-NMR spectroscopy, and N2 adsorption-desorption analyses.

    Science.gov (United States)

    Peña, Brisa; de Ménorval, Louis-Charles; Garcia-Valls, Ricard; Gumí, Tània

    2011-11-01

    Textile detergent and softener industries have incorporated perfume microencapsulation technology to improve their products. Perfume encapsulation allows perfume protection until use and provides a long-lasting fragrance release. But, certain industrial microcapsules show low encapsulation capacity and low material stability. Polysulfone capsules have been already proposed to solve these drawbacks. Among them, PSf/Vanillin capsules were considered as a desirable system. They present both good material stability and high encapsulation capacity. However, several factors such as the final location of the perfume in the polymeric matrix, the aggregation state that it has in the capsule and its interaction with the capsule components have not been studied yet. These factors can provide vast information about the capsule performance and its improvement. With the aim to characterize these parameters, the physical and chemical properties of PSf/Vanillin capsules have been investigated by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and N(2) adsorption-desorption measurements. AFM micrograph and N(2) isotherms confirm that the presence of vanillin modify the physical structure of PSf/Vanillin microcapsules as it is trapped in the capsule porosity. NMR results show that vanillin is present in solid state in PSf/Vanillin microcapsules.

  13. In vivo 13C NMR metabolite profiling: potential for understanding and assessing conifer seed quality.

    Science.gov (United States)

    Terskikh, Victor V; Feurtado, J Allan; Borchardt, Shane; Giblin, Michael; Abrams, Suzanne R; Kermode, Allison R

    2005-08-01

    High-resolution 13C MAS NMR spectroscopy was used to profile a range of primary and secondary metabolites in vivo in intact whole seeds of eight different conifer species native to North America, including six of the Pinaceae family and two of the Cupressaceae family. In vivo 13C NMR provided information on the total seed oil content and fatty acid composition of the major storage lipids in a non-destructive manner. In addition, a number of monoterpenes were identified in the 13C NMR spectra of conifer seeds containing oleoresin; these compounds showed marked variability in individual seeds of Pacific silver fir within the same seed lot. In imbibed conifer seeds, the 13C NMR spectra showed the presence of considerable amounts of dissolved sucrose presumed to play a protective role in the desiccation-tolerance of seeds. The free amino acids arginine and asparagine, generated as a result of storage protein mobilization, were detected in vivo during seed germination and early seedling growth. The potential for NMR to profile metabolites in a non-destructive manner in single conifer seeds and seed populations is discussed. It is a powerful tool to evaluate seed quality because of its ability to assess reserve accumulation during seed development or at seed maturity; it can also be used to monitor reserve mobilization, which is critical for seedling emergence. PMID:15996983

  14. Structural properties of carbon nanotubes derived from 13C NMR

    KAUST Repository

    Abou-Hamad, E.

    2011-10-10

    We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled carbon nanotubes with diameters in the range from 0.7 to 100 nm and with number of walls from 1 to 90. We provide models on how diameter and the number of nanotube walls influence NMR linewidth and line position. Both models are supported by theoretical calculations. Increasing the diameter D, from the smallest investigated nanotube, which in our study corresponds to the inner nanotube of a double-walled tube to the largest studied diameter, corresponding to large multiwalled nanotubes, leads to a 23.5 ppm diamagnetic shift of the isotropic NMR line position δ. We show that the isotropic line follows the relation δ = 18.3/D + 102.5 ppm, where D is the diameter of the tube and NMR line position δ is relative to tetramethylsilane. The relation asymptotically tends to approach the line position expected in graphene. A characteristic broadening of the line shape is observed with the increasing number of walls. This feature can be rationalized by an isotropic shift distribution originating from different diamagnetic shielding of the encapsulated nanotubes together with a heterogeneity of the samples. Based on our results, NMR is shown to be a nondestructive spectroscopic method that can be used as a complementary method to, for example, transmission electron microscopy to obtain structural information for carbon nanotubes, especially bulk samples.

  15. Phenyl galactopyranosides – {sup 13}C CPMAS NMR and conformational analysis using genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Wałejko, Piotr, E-mail: pwalejko@uwb.edu.pl [University of Bialystok, Institute of Chemistry, Pilsudskiego 11/4, 15-443 Bialystok (Poland); Paradowska, Katarzyna, E-mail: katarzyna.paradowska@wum.edu.pl [Medical University of Warsaw, Faculty of Pharmacy, Department of Physical Chemistry, Banacha 1, 02-097 Warsaw (Poland); Bukowicki, Jarosław [Medical University of Warsaw, Faculty of Pharmacy, Department of Physical Chemistry, Banacha 1, 02-097 Warsaw (Poland); Witkowski, Stanisław [University of Bialystok, Institute of Chemistry, Pilsudskiego 11/4, 15-443 Bialystok (Poland); Wawer, Iwona [Medical University of Warsaw, Faculty of Pharmacy, Department of Physical Chemistry, Banacha 1, 02-097 Warsaw (Poland)

    2015-08-18

    Highlights: • The structures of phenyl galactosides were studied by {sup 13}C CPMAS NMR. • The GAAGS method was used in conformational analysis of phenyl galactosides. • The rotation of the aglycone was investigated. • {sup 13}C CPMAS NMR supported by GIAO DFT calculations was used as a verification method. - Abstract: Structural analyses of four compounds (phenyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside (1), phenyl β-D-galactopyranoside (2), phenyl 2,3,4,6-tetra-O-acetyl-α-D-galactopyranoside (3) and phenyl α-D-galactopyranoside (4)) have been performed using solid-state {sup 13}C MAS NMR spectroscopy and theoretical methods. Conformational analysis involved grid search and genetic algorithm (GAAGS). Low-energy conformers found by GAAGS were further optimized by DFT and chemical shifts were calculated using GIAO/DFT approach. {sup 13}C CPMAS NMR chemical shift of carbon C2 is indicative of the glycoside torsional angle. Separated or merged resonances of C2 and C6 suggest free rotation of phenyl ring in the solid phase.

  16. Phenyl galactopyranosides – 13C CPMAS NMR and conformational analysis using genetic algorithm

    International Nuclear Information System (INIS)

    Highlights: • The structures of phenyl galactosides were studied by 13C CPMAS NMR. • The GAAGS method was used in conformational analysis of phenyl galactosides. • The rotation of the aglycone was investigated. • 13C CPMAS NMR supported by GIAO DFT calculations was used as a verification method. - Abstract: Structural analyses of four compounds (phenyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside (1), phenyl β-D-galactopyranoside (2), phenyl 2,3,4,6-tetra-O-acetyl-α-D-galactopyranoside (3) and phenyl α-D-galactopyranoside (4)) have been performed using solid-state 13C MAS NMR spectroscopy and theoretical methods. Conformational analysis involved grid search and genetic algorithm (GAAGS). Low-energy conformers found by GAAGS were further optimized by DFT and chemical shifts were calculated using GIAO/DFT approach. 13C CPMAS NMR chemical shift of carbon C2 is indicative of the glycoside torsional angle. Separated or merged resonances of C2 and C6 suggest free rotation of phenyl ring in the solid phase

  17. 13C-NMR Data of Three Important Diterpenes Isolated from Euphorbia Species

    Directory of Open Access Journals (Sweden)

    Fen-Qiang You

    2009-11-01

    Full Text Available Euphorbia species are widely distributed plants, many of which are used in folk medicine. Over the past twenty years, they have received considerable phytochemical and biological attention. Their diterpenoid constituents, especially those with abietane, tigliane, ingenane skeletons, are thought to be the main toxicant and bioactive factors. In this work, the utility of 13C-NMR spectroscopy for the structural elucidation of these compounds is briefly discussed.

  18. 13C CPMAS NMR Studies of Anthocyanidins and their Glucosides

    International Nuclear Information System (INIS)

    Anthocyanins are responsible for red, purple or blue colours of flower petals and can be found in red or black fruits and berries. Many foods, especially red grapes and wines, aronia or blueberries contain large amounts of anthocyanins. Their health beneficial effects are related to antioxidant and radical scavenging properties. Structural analysis of anthocyanins by NMR are few, owing to the difficulty in obtaining analysable spectra for unstable, interconverting compounds, available in small amounts. Compounds studied by us were isolated from fruits and berries. 13C CPMAS NMR spectra were recorded on a Bruker DSX-400 spectrometer for solid chlorides of: cyanidin, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, pelargonidin and pelargonidin 3-O-glucoside. Dipolar dephased and short contact pulse sequences were used as an aid in the assignment of resonances in CPMAS spectra of solids. Inspection of the spectra indicates that anthocyanidins are in the form of flavylium (cationic) and not in form of the chalcone.: the resonance of C2 appears at ca. 160 ppm and C3 at ca. 135 ppm, whereas C ring opening produces C2 = O, for which chemical shift of ca. 180 ppm can be expected. A comparison of experimental (CPMAS) and predicted (GIAO DFT) shielding constants for cyanidin provided information about the orientation of OH groups, twist angle of aromatic ring B and the localization of the chloride anion.(author)

  19. 1H and 13C NMR investigation of 20-hydroxyecdysone dioxolane derivatives, a novel group of MDR modulator agents.

    Science.gov (United States)

    Balázs, Attila; Hunyadi, Attila; Csábi, József; Jedlinszki, Nikoletta; Martins, Ana; Simon, András; Tóth, Gábor

    2013-12-01

    The synthesis, structure elucidation and the complete (1)H and (13)C signal assignment of a series of dioxolane derivatives of 20-hydroxyecdysone, synthesized as novel modulators of multidrug resistance, are presented. The structures and NMR signal assignment were established by comprehensive one-dimensional and two-dimensional NMR spectroscopy supported by mass spectrometry. PMID:24114927

  20. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    Science.gov (United States)

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  1. Solid state 13C NMR characterisation study on fourth generation Ziegler-Natta catalysts.

    Science.gov (United States)

    Heikkinen, Harri; Liitiä, Tiina; Virkkunen, Ville; Leinonen, Timo; Helaja, Tuulamari; Denifl, Peter

    2012-01-01

    In this study, solid state (13)C NMR spectroscopy was utilised to characterize and identify the metal-ester coordination in active fourth generation (phthalate) Ziegler-Natta catalysts. It is known that different donors affect the active species in ZN catalysts. However, there is still limited data available of detailed molecular information how the donors and the active species are interplaying. One of the main goals of this work was to get better insight into the interactions of donor and active species. Based on the anisotropy tensor values (δ(11), δ(22), δ(33)) from low magic-angle spinning (MAS) (13)C NMR spectra in combination with chemical shift anisotropy (CSA) calculations (δ(aniso) and η), both the coordinative metal (Mg/Ti) and the symmetry of this interaction between metal and the internal donor in the active catalyst (MgCl(2)/TiCl(4)/electron donor) system could be identified. PMID:22425229

  2. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ In proton broad band decoupling 13C NMR, carbon atoms have different integration intensity because of NOE effects and their different relaxation time(T1), thus it makes a 13C NMR quantitative analyses very difficult. To acquire a 3C NMR quantitative analyses, a gated decoupling with suppressed NOE technology, i.e., an inversed gated decoupling pulse (IGDP), must be used. In IGDP relay time (tR) between two acquisition cycles must be more than 5T1, the time needed for a acquisition cycles is so long that makes the total 13C NMR quantitative analyses time much longer. For this reason, the 13C NMR quantitative analyses is paid less attention.

  3. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    Institute of Scientific and Technical Information of China (English)

    TIAN; JinPing

    2001-01-01

    In proton broad band decoupling 13C NMR, carbon atoms have different integration intensity because of NOE effects and their different relaxation time(T1), thus it makes a 13C NMR quantitative analyses very difficult. To acquire a 3C NMR quantitative analyses, a gated decoupling with suppressed NOE technology, i.e., an inversed gated decoupling pulse (IGDP), must be used. In IGDP relay time (tR) between two acquisition cycles must be more than 5T1, the time needed for a acquisition cycles is so long that makes the total 13C NMR quantitative analyses time much longer. For this reason, the 13C NMR quantitative analyses is paid less attention.  ……

  4. 13C NMR and EPR spectroscopic evaluation of oil shale mined soil recuperation

    International Nuclear Information System (INIS)

    In this work, native forest soil (NFS) organic matter (SOM) sample and SOM samples from a neighboring forest soil area of an oil shale mine which is being rehabilitated for thirty years (RFS) were analyzed. X-band electron paramagnetic resonance (EPR) and solid-state 13C nuclear magnetic resonance (NMR) spectroscopies were used to evaluate the soil reclamation of the Brazilian oil shale mining process. Two-dimensional heterospectral correlation studies of the results obtained from EPRand 13C NMR were used to obtain information about SOM structures and their interactions with residual paramagnetic metal ion. The signal of the residual metallic oxycation, VO2+ correlated positively with uronic acid-type hydrophilic organic structures, determined from the 13C NMR spectra, and correlated negatively with the organic free radical (OFR) signal associated with oxygen atoms (g = 2.0042). The hydrophobic aromatic structures correlate positively with the EPR OFR signal associated with carbon atoms (g = 2.0022). The data from the two spectroscopic magnetic techniques show that the used recuperation process is effective. (author)

  5. {sup 13}C NMR and EPR spectroscopic evaluation of oil shale mined soil recuperation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.V. dos, E-mail: mangrich@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Mangrich, A.S. [Instituto Nacional de Ciencia e Tecnologia: Energia e Ambiente, Salvador, BA (Brazil); Pereira, B.F. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil); Pillon, C.N. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil). Estacao Experimental Cascata; Novotny, E.H. [EMBRAPA Solos, Rio de Janeiro, RJ (Brazil); Bonagamba, T.J. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica; Abbt-Braun, G.; Frimmel, F.H. [Engler-Bunte-Institut, Universitaet Karlsruhe, TH (Germany)

    2013-02-15

    In this work, native forest soil (NFS) organic matter (SOM) sample and SOM samples from a neighboring forest soil area of an oil shale mine which is being rehabilitated for thirty years (RFS) were analyzed. X-band electron paramagnetic resonance (EPR) and solid-state {sup 13}C nuclear magnetic resonance (NMR) spectroscopies were used to evaluate the soil reclamation of the Brazilian oil shale mining process. Two-dimensional heterospectral correlation studies of the results obtained from EPRand {sup 13}C NMR were used to obtain information about SOM structures and their interactions with residual paramagnetic metal ion. The signal of the residual metallic oxycation, VO{sup 2+} correlated positively with uronic acid-type hydrophilic organic structures, determined from the {sup 13}C NMR spectra, and correlated negatively with the organic free radical (OFR) signal associated with oxygen atoms (g = 2.0042). The hydrophobic aromatic structures correlate positively with the EPR OFR signal associated with carbon atoms (g = 2.0022). The data from the two spectroscopic magnetic techniques show that the used recuperation process is effective. (author)

  6. Solid-, Solution-, and Gas-state NMR Monitoring of 13C-Cellulose Degradation in an Anaerobic Microbial Ecosystem

    Directory of Open Access Journals (Sweden)

    Yasuhiro Date

    2013-07-01

    Full Text Available Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. 13C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and 13C-13C/13C-12C isotopomers in the microbial degradation of 13C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid.

  7. Study on Effects of Acidic Extraction on Yield and Structure of Tobacco Pectin by CP/MAS 13C NMR Spectroscopy%CP/MAS 13C NMR技术分析酸提取对烟草果胶产率和结构的影响

    Institute of Scientific and Technical Information of China (English)

    李东亮; 谭兰兰; 高芸; 朱晓兰; 戴亚

    2015-01-01

    In order to investigate the fine structure of tobacco pectin and the key factors in extraction, the effects of extraction conditions (including pH, temperature and extraction time) on the yield, purity and structure of pectin were studied by cross-polarization/magic angle spinning 13C nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy. The results showed that: 1) The highest pectin yield (10.87%) achieved after extracting for 1.5 hours at pH 1.5 and 85 ℃; while polygalacturonic acid(PGA)reached its highest purity (78.4%) after extracting for 1.5 hours at pH 2.0 and 95 ℃. 2) The extraction conditions influenced the structure of pectin to a certain extent, the degrees of methylation (DM) and acetylation (DA) of pectin increased as pH value increased from 1.5 to 2.5, while decreased with the rise of temperature and the prolongation of extraction time significantly.%为研究烟草果胶的精细结构和掌握果胶提取的关键因素,采用交叉极化/魔角旋转固态核磁光谱技术(CP/MAS 13C NMR)考察了酸提取条件(pH、温度和提取时间)对烟草果胶产率、纯度(质量分数)及结构的影响。结果表明:①在pH 1.5和85℃条件下提取1.5 h时,烟草果胶得率最高,为10.87%,但在pH 2.0和95℃条件下提取1.5 h时,聚半乳糖醛酸(PGA)的纯度最高,为78.4%。②提取条件对烟草果胶的结构也有一定的影响,pH=1.5~2.5时,果胶的甲酯度(DM)和乙酰度(DA)均随pH升高而增大,随温度升高而降低,随提取时间延长而显著下降。

  8. Pulsed polarization transfer for 13C NMR in solids

    Science.gov (United States)

    Bax, Ad; Szeverenyi, Nikolaus M.; Maciel, Gary E.

    A new pulsed polarization transfer experiment method is described for the polarization of 13C spins in a solid by magnetization transfer from protons. The method is directly analogous to the INEPT sequence for liquids introduced by Freeman and Morris. As polarization is transferred in PPT between individual 1H 13C pairs, rather than between spin reservoirs, different opportunities exist for structurally selective experiments. Results on p-diethoxybenzene and coronene are presented.

  9. 13C-NMR detection of lipid polymorphism in model and biological membranes

    NARCIS (Netherlands)

    Kruijff, B. de; Rietveld, A.; Echteld, C.J.A. van

    1980-01-01

    1. 1. The application of the 13C-NMR technique to the study of lipid polymorphism is described for various model and biological membranes. 2. 2. The 13C-NMR line-width of various resonances of the lipid molecule are sensitive to the bilayer hexagonal and the bilayer ‘isotropic’ phase transition.

  10. MEASUREMENT OF NUMBER AVERAGE MOLECULAR WEIGHT OF STYRENE OLIGOMER BY 13C-NMR METHOD

    Institute of Scientific and Technical Information of China (English)

    Song Wang; Xiao-hu Yan; Rong-shi Cheng

    1999-01-01

    13C-NMR 1H-decoupled spectra of styrene polymers were assigned by comparison with model compounds, then used in measurements of number average molecular weights. The higher limit of an exact determination of the end group signal is less than a molecular weight of 104. For polymer samples with Mn<103, the results obtained from 13C-NMR spectra of saturated carbon region are in excellent agreement with the values determined by 1H-NMR, SEC, and VPO methods, while the results from 13C-NMR spectra of phenyl C-1 carbon region are somewhat higher than the values determined by other methods.

  11. Complete {sup 1}H and {sup 13}C NMR assignments of isojuripidine from Solanum asterophorum Mart

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Tania M.S.; Costa, Rodrigo A.; Oliveira, Eduardo J.; Barbosa-Filho, Jose M.; Agra, Maria F.; Camara, Celso A. [Universidade Federal da Paraiba, Joao Pessoa, PB (Brazil). Lab. de Tecnologia Farmaceutica]. E-mail: sarmento@ltf.ufpb.br

    2005-11-15

    Isojuripidine was isolated from the aerial parts of Solanum astherophorum Mart. Its structure was determined using a combination of homo- (1D {sup 1}H NMR, {sup 13}C NMR-HBBD and {sup 13}C NMRDEPT) and heteronuclear 2D NMR techniques ({sup 1}H-{sup 1}H-COSY, {sup 1}H-{sup 1}H-NOESY, HSQC, HMBC), and HREIMS. The unambiguous assignments of {sup 1}H and {sup 13}C NMR data of derivatives 3-N,6-Odiacetyl- isojuripidine and 3-N-cinnamoyl-isojuripidine are described. (author)

  12. Neuroprotective effects of caffeine in MPTP model of Parkinson's disease: A (13)C NMR study.

    Science.gov (United States)

    Bagga, Puneet; Chugani, Anup N; Patel, Anant B

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons with an accompanying neuroinflammation leading to loss of dopamine in the basal ganglia. Caffeine, a well-known A2A receptor antagonist is reported to slow down the neuroinflammation caused by activated microglia and reduce the extracellular glutamate in the brain. In this study, we have evaluated the neuroprotective effect of caffeine in the MPTP model of PD by monitoring the region specific cerebral energy metabolism. Adult C57BL6 mice were treated with caffeine (30 mg/kg, i.p.) 30 min prior to MPTP (25 mg/kg, i.p.) administration for 8 days. The paw grip strength of mice was assessed in order to evaluate the motor function after various treatments. For metabolic studies, mice were infused with [1,6-(13)C2]glucose, and (13)C labeling of amino acids was monitored using ex vivo(1)H-[(13)C]-NMR spectroscopy. The paw grip strength was found to be reduced following the MPTP treatment. The caffeine pretreatment showed significant protection against the reduction of paw grip strength in MPTP treated mice. The levels of GABA and myo-inositol were found to be elevated in the striatum of MPTP treated mice. The (13)C labeling of GluC4, GABAC2 and GlnC4 from [1,6-(13)C2]glucose was decreased in the cerebral cortex, striatum, olfactory bulb, thalamus and cerebellum suggesting impaired glutamatergic and GABAergic neuronal activity and neurotransmission of the MPTP treated mice. Most interestingly, the pretreatment of caffeine maintained the (13)C labeling of amino acids to the control values in cortical, olfactory bulb and cerebellum regions while it partially retained in striatal and thalamic regions in MPTP treated mice. The pretreatment of caffeine provides a partial neuro-protection against severe striatal degeneration in the MPTP model of PD.

  13. STUDY ON THE SEQUENCE STRUCTURE OF SBR BY 13C- NMR METHOD Ⅰ. ASSIGNMENT FOR UNSATURATED CARBONS SPECTRA

    Institute of Scientific and Technical Information of China (English)

    JIAO Shuke; CHEN Xiaonong; HU Liping; YAN Baozhen

    1990-01-01

    The sequence structures of emulsion- processed SBR and solution- processed ( by lithium catalyst )SBR were investigated by 13C- NMR spectroscopy. Seventeen peaks within unsaturated carbon region were recorded under the adopted experimental conditions. Assignments for these peaks were made by empirical- parameter- evaluation method.

  14. 13C-NMR of forest soil lipids

    OpenAIRE

    Almendros Martín, Gonzalo; Tinoco, Pilar; González-Vila, Francisco Javier; Lüdemann, H.-D.; Sanz Perucha, Jesús; Velasco de Pedro, F.

    2001-01-01

    Molecular characterization of soil lipids often provides valuable biogeochemical information about the impact of vegetation, microorganisms, and abiotic factors on the soil C sequestration process. The total lipid extracted with petroleum ether from nine soils developed under three types of Mediterranean forest (stone pine (Pinus pinea L.), evergreen oak (Quercus rotundifolia L.), and Spanish juniper (Juniperus thurifera L)) has been analyzed by high-resolution 13C nuclear magnetic resonance ...

  15. 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...

  16. 13C and 31P NMR [Nuclear Magnetic Resonance] studies of prostate tumor metabolism

    International Nuclear Information System (INIS)

    The current research on prostate cancer by NMR spectroscopy and microscopy will most significantly contribute to tumor diagnosis and characterization only if sound biochemical models of tumor metabolism are established and tested. Prior searches focused on universal markers of malignancy, have to date, revealed no universal markers by any method. It is unlikely that NMRS will succeed where other methods have failed, however, NMR spectroscopy does provide a non-invasive means to analyze multiple compounds simultaneously in vivo. In order to fully evaluate the ability of NMRS to differentiate non-malignant from malignant tissues it is necessary to determine sufficient multiple parameters from specific, well-diagnosed, histological tumor types that, in comparison to normal tissue and non-neoplastic, non-normal pathologies from which the given neoplasm must be differentiated, one has enough degrees of freedom to make a mathematically and statistically significant determination. Confounding factors may consist of tumor heterogeneity arising from regional variations in differentiation, ischemia, necrosis, hemorrhage, inflammation and the presence of intermingled normal tissue. One related aspect of our work is the development of {13C}-1H metabolic imaging of 13C for metabolic characterization, with enhanced spatial localization (46). This should markedly extend the range of potential clinical NMR uses because the spatial variation in prostate metabolism may prove to be just as important in tumor diagnoses as bulk (volume-averaged) properties themselves. It is our hope that NMRS and spectroscopic imaging will reveal a sound correlation between prostate metabolism and tumor properties that will be clinically straightforward and useful for diagnosis

  17. Assignments of 1H and 13C NMR Signals of Mogroside IVa

    Institute of Scientific and Technical Information of China (English)

    ZHANGJian-ye; YANGXiu-wei

    2003-01-01

    Aim To investigate the structure of mogroside IVa isolated from traditional Chinese medicine fructus momordicae [fruits of Siraitia grosvenori (Swingle) C. Jeffery] and summarize the NMR characteristics of the structure. Methods Cormnon extraction, separafion and purification methods were used. Various NMR techniques including 1H NMR,13C NMR, DEPT, 1H-1H COSY, HSQC, HMBC, NOESY and molecular model simulated by comtmter were used to elucidate the structure. Results 1H and 13C NMR signals of mogroside IVa were assigned, and spectroscopic basis was obtained for identification of such type of compounds. Conclusion 1D and 2D NMR techniques including 1H-1H COSY, HSQC, HMBC, NOESY spectra are powerful tools for structure analysis. The structure determined by NMR methods is identical with energy minimized conformation simulated by computer.

  18. 13C solid-state NMR of gramicidin A in a lipid membrane.

    OpenAIRE

    Quist, P O

    1998-01-01

    The natural-abundance 13C NMR spectrum of gramicidin A in a lipid membrane was acquired under magic-angle spinning conditions. With fast sample spinning (15 kHz) at approximately 65 degrees C the peaks from several of the aliphatic, beta-, alpha-, aromatic, and carbonyl carbons in the peptide could be resolved. The resolution in the 13C spectrum was superior that observed with 1H NMR under similar conditions. The 13C linewidths were in the range 30-100 Hz, except for the alpha- and beta-carbo...

  19. Static and dynamic interaction between π and d electrons in organic superconductor β″-(BEDT-TTF)4[(H3O ) Fe (C2O4)3] .C6H5Br studied by 13C NMR spectroscopy

    Science.gov (United States)

    Ihara, Y.; Futami, Y.; Kawamoto, A.; Matsui, K.; Goto, T.; Sasaki, T.; Benmansour, S.; Gómez-García, C. J.

    2016-08-01

    We present the results of 13C NMR experiments in an organic superconductor with localized Fe spins β″-(BEDT-TTF) 4[(H3O ) Fe (C2O4)3] .C6H5Br . We reveal the antiferromagnetic coupling between Fe d spins and π spins, which creates an exchange field antiparallel to the external field direction at the π electrons. In addition to the static effects of Fe spins, we show from the nuclear spin-lattice relaxation rate measurement that the magnetic fluctuations generated by Fe spins are suppressed at low temperatures and high magnetic fields. These conditions are suitable to stabilize the field-induced superconductivity by the field compensation mechanism. After the suppression of Fe-spin dynamics by a magnetic field of 19 T, we observed the underlying π -electron contribution. We discuss a possible anomaly in the π -electron system.

  20. Aspects of reaction of N-oxide radical with ethers in 13C NMR spectrum

    International Nuclear Information System (INIS)

    The stable radical N-oxide 2,2,6,6-tetramethylpiperidine was dissolved in ethers. The 13C NMR spectra were recorded in the temperature 313K at the frequency 22,625 MHz on the spectrometers with Fourier transformation. The dissolution of the radical in ether caused the contact shifts in NMR spectra. The shifts were measured. (A.S.)

  1. 13C nuclear magnetic resonance spectroscopy in the studies of biosynthetic routes of natural products

    International Nuclear Information System (INIS)

    During the last five decades, as a result of an interaction between natural product chemistry, synthetic organic chemistry, molecular biology and spectroscopy, scientists reached an extraordinary level of comprehension about the natural processes by which living organisms build up complex molecules. In this context, 13C nuclear magnetic resonance spectroscopy, allied with isotopic labeling, played a determinant role. Nowadays, the widespread use of modern NMR techniques allows an even more detailed picture of the biochemical steps by accurate manipulation of the atomic nuclei. This article focuses on the development of such techniques and their impact on biosynthetic studies. (author)

  2. Comprehensive signal assignment of 13C-labeled lignocellulose using multidimensional solution NMR and 13C chemical shift comparison with solid-state NMR.

    Science.gov (United States)

    Komatsu, Takanori; Kikuchi, Jun

    2013-09-17

    A multidimensional solution NMR method has been developed using various pulse programs including HCCH-COSY and (13)C-HSQC-NOESY for the structural characterization of commercially available (13)C labeled lignocellulose from potatoes (Solanum tuberosum L.), chicory (Cichorium intybus), and corn (Zea mays). This new method allowed for 119 of the signals in the (13)C-HSQC spectrum of lignocelluloses to be assigned and was successfully used to characterize the structures of lignocellulose samples from three plants in terms of their xylan and xyloglucan structures, which are the major hemicelluloses in angiosperm. Furthermore, this new method provided greater insight into fine structures of lignin by providing a high resolution to the aromatic signals of the β-aryl ether and resinol moieties, as well as the diastereomeric signals of the β-aryl ether. Finally, the (13)C chemical shifts assigned in this study were compared with those from solid-state NMR and indicated the presence of heterogeneous dynamics in the polysaccharides where rigid cellulose and mobile hemicelluloses moieties existed together. PMID:24010724

  3. 13C-NMR chemical shift databases as a quick tool to evaluate structural models of humic substances

    DEFF Research Database (Denmark)

    Nyrop Albers, Christian; Hansen, Poul Erik

    2010-01-01

    Models for humic and fulvic acids are discussed based on 13C liquid state NMR spectra combined with results from elemental analysis and titration studies. The analysis of NMR spectra is based on a full reconstruction of the NMR spectrum done with help of 13C-NMR data bases by adding up chemical s...

  4. Cigarette butt decomposition and associated chemical changes assessed by 13C CPMAS NMR.

    Science.gov (United States)

    Bonanomi, Giuliano; Incerti, Guido; Cesarano, Gaspare; Gaglione, Salvatore A; Lanzotti, Virginia

    2015-01-01

    Cigarette butts (CBs) are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack.

  5. Cigarette butt decomposition and associated chemical changes assessed by 13C CPMAS NMR.

    Directory of Open Access Journals (Sweden)

    Giuliano Bonanomi

    Full Text Available Cigarette butts (CBs are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack.

  6. The use of dynamic nuclear polarization in 1H and 13C solid state NMR

    International Nuclear Information System (INIS)

    The Dynamic Nuclear Polarization (DNP) effect is used at room temperature in combination with 13C NMR. Due to the low natural abundance of 13C spins (1%) the signal is very weak, but when the DNP effect is used the 13C signal can be enhanced and therefore the number of scans and the measuring time considerably reduced. The theory is presented and the experimental set-up is described. Experiments on polystyrene, artificially doped with free radicals are described and it is examined whether the theory of the DNP effect can be used in a quantitative way. Applications of the use of the DNP effect in 13C NMR are shown. Excellent spectra are presented of artificial and natural diamonds, possibly to be used for diamond characterization purposes. 161 refs.; 61 figs.; 3 tabs

  7. [Characterization of biochar by X-ray photoelectron spectroscopy and 13C nuclear magnetic resonance].

    Science.gov (United States)

    Xu, Dong-yu; Jin, Jie; Yan, Yu; Han, Lan-fang; Kang, Ming-jie; Wang, Zi-ying; Zhao, Ye; Sun, Ke

    2014-12-01

    The wood (willow branch) and grass (rice straw) materials were pyrolyzed at different temperatures (300, 450 and 600 °C) to obtain the biochars used in the present study. The biochars were characterized using elementary analysis, X-ray photoelectron spectroscopy (XPS) and solid state 13C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy (13C NMR) to illuminate the structure and composition of the biochars which were derived from the different thermal temperatures and biomass. The results showed that the H/C, O/C and (O+N)/C ratios of the biochars decreased with the increase in the pyrolysis temperatures. The surface polarity and ash content of the grass-derived biochars were higher than those of the wood-derived biochars. The minerals of the wood-derived biochars were mainly covered by the organic matter; in contrast, parts of the mineral surfaces of the grass-derived biochars were not covered by organic matter? The 13C NMR of the low temperature-derived biochars revealed a large contribution of aromatic carbon, aliphatic carbon, carboxyl and carbonyl carbon, while the high temperature-derived biochars contained a large amount of aromatic carbon. Moreover, the wood-derived biochars produced at low heat treatment temperatures contained more lignin residues than grass-derived ones, probably due to the existence of high lignin content in the feedstock soures of wood-derived biochars. The results of the study would be useful for environmental application of biochars.

  8. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    Science.gov (United States)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  9. Assignment of the ferriheme resonances of high- and low-spin forms of the symmetrical hemin-reconstituted nitrophorins 1-4 by 1H and 13C NMR spectroscopy: the dynamics of heme ruffling deformations.

    Science.gov (United States)

    Shokhireva, Tatiana K; Shokhirev, Nikolai V; Berry, Robert E; Zhang, Hongjun; Walker, F Ann

    2008-08-01

    The four major nitrophorins (NPs) of the adult blood-sucking insect Rhodnius prolixus have been reconstituted with the "symmetrical hemin" 2,4-dimethyldeuterohemin, and their NMR spectra have been investigated as the high-spin (S=5/2) aqua and low-spin (S=1/2) N-methylimidazole (NMeIm) and cyanide complexes. The NMeIm complexes allow assignment of the high-spin hemin resonances by saturation transfer difference spectroscopy. The cyanide complexes were investigated as paramagnetic analogues of the NO complexes. It is shown that the hemin ring is highly distorted from planarity, much more so for NP2 than for NP1 and NP4 (with ruffling being the major distortion mode), for both high- and low-spin forms. For the cyanide complexes, the conformation of the distorted ring changes on the NMR timescale to yield chemical exchange (exchange spectroscopy, EXSY) cross peaks for NP1sym(CN), NP3sym(CN) and NP4sym(CN) but not for NP2sym(CN). These changes in nonplanar conformation are visualized as a "rolling" of the ruffled macrocycle ridges through some number of degrees, the lowest-energy ruffling mode. This probably occurs in response to slow protein dynamics that cause the I120 and L132 side chains in the distal heme pocket to move in opposite directions (up and away vs. down and toward the hemin ring). This in turn changes the out-of-plane displacements of the 2M and 3M of the symmetrical hemin on the NMR timescale. Two other types of dynamics, i.e., changes in heme seating and NMeIm rotation, are also observed. The highly distorted heme and the dynamics it causes are unique to the NPs and a few other heme proteins with highly distorted macrocycles. PMID:18458965

  10. Structure and dynamics of homoleptic beryllocenes: a solid-state 9Be and 13C NMR study.

    Science.gov (United States)

    Hung, Ivan; Macdonald, Charles L B; Schurko, Robert W

    2004-11-19

    The correlation between anisotropic 9Be NMR (quadrupolar and chemical shielding) interactions and the structure and dynamics in [Cp2Be], [Cp2*Be], and [(C5Me4H)2Be] is examined by solid-state 9Be NMR spectroscopy, as well as by ab initio and hybrid density functional theory calculations. The 9Be quadrupole coupling constants in the three compounds correspond well to the relative degrees of spherical ground-state electronic symmetry of the environment about beryllium. Theoretical computations of NMR interaction tensors are in excellent agreement with experimental values and aid in understanding the origins of NMR interaction tensors and their correlation to molecular symmetry. Variable-temperature (VT) 9Be and 13C NMR experiments reveal a highly fluxional structure in the condensed phase of [Cp2Be]. In particular, the pathway by which the Cp rings of [Cp2Be] 'invert' coordination modes is examined in detail using hybrid density functional theory in order to inspect variations of the 9Be NMR interaction tensors. The activation energy for the 'inversion' process is found to be 36.9 kJ mol(-1) from chemical exchange analysis of 13C VT CP/MAS NMR spectra. The low-temperature (ca. -100 degrees C) X-ray crystal structures of all three compounds have been collected and refined, and are in agreement with previously reported structures. In addition, the structure of the same Cp2Be crystal was determined at 20 degrees C and displays features consistent with increased intramolecular motion, supporting observations by 9Be VT NMR spectroscopy. PMID:15484199

  11. Analysis of germination of castor and peanuts seeds by 13C NMR

    International Nuclear Information System (INIS)

    Germination of castor and peanut seeds was followed by 13C NMR. Results are comparable to those observed for soybean seeds and reveal that this technique is generally applicable in cases in which a reasonable amount of soluble material is present during germination. Different pathways for oil degradation by castor and peanut seeds may be distinguished. (Author)

  12. Chain Length Effects of Linear Alkanes in Zeolite Ferrierite. 1. Sorption and 13C NMR Experiments

    NARCIS (Netherlands)

    Well, van Willy J.M.; Cottin, Xavier; Haan, vde Jan W.; Smit, Berend; Nivarthy, Gautam; Lercher, Johannes A.; Hooff, van Jan H.C.; Santen, van Rutger A.

    1998-01-01

    Temperature-programmed desorption, heat of adsorption, adsorption isotherm, and 13C NMR measurements are used to study the sorption properties of linear alkanes in ferrierite. Some remarkable chain length effects are found in these properties. While propane, n-butane, and n-pentane fill the ferrieri

  13. Solid state {sup 13}C NMR analysis of Brazilian cretaceous ambers

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Ricardo; Azevedo, Debora A., E-mail: ricardopereira@iq.ufrj.b, E-mail: debora@iq.ufrj.b [Universidade Federal do Rio de Janeiro (IQ/UFRJ), Rio de Janeiro, RJ (Brazil). Inst. de Quimica. Lab. de Geoquimica Organica Molecular e Ambiental; San Gil, Rosane A.S. [Universidade Federal do Rio de Janeiro (IQ/UFRJ), RJ (Brazil). Inst. de Quimica. Lab. de RMN de Solidos; Carvalho, Ismar S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Geociencias. Dept. de Geologia; Fernandes, Antonio Carlos S. [Museu Nacional (MN/UFRJ), RJ (Brazil). Dept. de Geologia e Paleontologia

    2011-07-01

    {sup 13}C cross polarization with magic angle spinning nuclear magnetic resonance ({sup 13}C CPMAS NMR) spectra have been obtained for the first time to three Cretaceous amber samples from South America. The samples were dated to Lower Cretaceous and collected in sediments from the Amazonas, Araripe and Reconcavo basins, Brazil. All samples have very similar spectra, consistent with a common paleobotanical source. Some aspects of the spectra suggest a relationship between Brazilian ambers and Araucariaceae family, such as intense resonances at 38-39 ppm. All samples are constituted by polylabdane structure associated to Class Ib resins, constituted by polymers of labdanoid diterpenes. Finally, information concerning some structural changes during maturation, such as isomerization of {Delta}{sup 8(17)} and {Delta}{sup 12(13)} unsaturations, were obtained by {sup 13}C NMR analyses. The results concerning botanical affinities are in accordance with previous results obtained by gas chromatography-mass spectrometry (GC-MS). (author)

  14. Occurrence, biological activities and {sup 13}C NMR data of amides from Piper (Piperaceae)

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Jeferson C. do; Paula, Vanderlucia F. de [Universidade Estadual do Sudoeste da Bahia, Jequie, BA (Brazil). Dept. de Quimica e Exatas; David, Jorge M. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; David, Juceni P., E-mail: jmdavid@ufba.br [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Fac. de Farmacia

    2012-07-01

    This manuscript describes an update review with up to 285 references concerning the occurrence of amides from a variety of species of the genus Piper (Piperaceae). Besides addressing occurrence, this review also describes the biological activities attributed to extracts and pure compounds, a compiled {sup 13}C NMR data set, the main correlations between structural and NMR spectroscopic data of these compounds, and employment of hyphened techniques such as LC-MS, GC-MS and NMR for analysis of amides from biological samples and crude Piper extracts. (author)

  15. DFT calculations of 1H and 13C NMR chemical shifts in transition metal hydrides.

    Science.gov (United States)

    del Rosal, I; Maron, L; Poteau, R; Jolibois, F

    2008-08-14

    Transition metal hydrides are of great interest in chemistry because of their reactivity and their potential use as catalysts for hydrogenation. Among other available techniques, structural properties in transition metal (TM) complexes are often probed by NMR spectroscopy. In this paper we will show that it is possible to establish a viable methodological strategy in the context of density functional theory, that allows the determination of 1H NMR chemical shifts of hydride ligands attached to transition metal atoms in mononuclear systems and clusters with good accuracy with respect to experiment. 13C chemical shifts have also been considered in some cases. We have studied mononuclear ruthenium complexes such as Ru(L)(H)(dppm)2 with L = H or Cl, cationic complex [Ru(H)(H2O)(dppm)2]+ and Ru(H)2(dppm)(PPh3)2, in which hydride ligands are characterized by a negative 1H NMR chemical shift. For these complexes all calculations are in relatively good agreement compared to experimental data with errors not exceeding 20% except for the hydrogen atom in Ru(H)2(dppm)(PPh3)2. For this last complex, the relative error increases to 30%, probably owing to the necessity to take into account dynamical effects of phenyl groups. Carbonyl ligands are often encountered in coordination chemistry. Specific issues arise when calculating 1H or 13C NMR chemical shifts in TM carbonyl complexes. Indeed, while errors of 10 to 20% with respect to experiment are often considered good in the framework of density functional theory, this difference in the case of mononuclear carbonyl complexes culminates to 80%: results obtained with all-electron calculations are overall in very satisfactory agreement with experiment, the error in this case does not exceed 11% contrary to effective core potentials (ECPs) calculations which yield errors always larger than 20%. We conclude that for carbonyl groups the use of ECPs is not recommended, although their use could save time for very large systems, for

  16. (13)C-NMR-Based Metabolomic Profiling of Typical Asian Soy Sauces.

    Science.gov (United States)

    Kamal, Ghulam Mustafa; Yuan, Bin; Hussain, Abdullah Ijaz; Wang, Jie; Jiang, Bin; Zhang, Xu; Liu, Maili

    2016-01-01

    It has been a strong consumer interest to choose high quality food products with clear information about their origin and composition. In the present study, a total of 22 Asian soy sauce samples have been analyzed in terms of (13)C-NMR spectroscopy. Spectral data were analyzed by multivariate statistical methods in order to find out the important metabolites causing the discrimination among typical soy sauces from different Asian regions. It was found that significantly higher concentrations of glutamate in Chinese red cooking (CR) soy sauce may be the result of the manual addition of monosodium glutamate (MSG) in the final soy sauce product. Whereas lower concentrations of amino acids, like leucine, isoleucine and valine, observed in CR indicate the different fermentation period used in production of CR soy sauce, on the other hand, the concentration of some fermentation cycle metabolites, such as acetate and sucrose, can be divided into two groups. The concentrations of these fermentation cycle metabolites were lower in CR and Singapore Kikkoman (SK), whereas much higher in Japanese shoyu (JS) and Taiwan (China) light (TL), which depict the influence of climatic conditions. Therefore, the results of our study directly indicate the influences of traditional ways of fermentation, climatic conditions and the selection of raw materials and can be helpful for consumers to choose their desired soy sauce products, as well as for researchers in further authentication studies about soy sauce. PMID:27598115

  17. 13C-NMR-Based Metabolomic Profiling of Typical Asian Soy Sauces

    Directory of Open Access Journals (Sweden)

    Ghulam Mustafa Kamal

    2016-09-01

    Full Text Available It has been a strong consumer interest to choose high quality food products with clear information about their origin and composition. In the present study, a total of 22 Asian soy sauce samples have been analyzed in terms of 13C-NMR spectroscopy. Spectral data were analyzed by multivariate statistical methods in order to find out the important metabolites causing the discrimination among typical soy sauces from different Asian regions. It was found that significantly higher concentrations of glutamate in Chinese red cooking (CR soy sauce may be the result of the manual addition of monosodium glutamate (MSG in the final soy sauce product. Whereas lower concentrations of amino acids, like leucine, isoleucine and valine, observed in CR indicate the different fermentation period used in production of CR soy sauce, on the other hand, the concentration of some fermentation cycle metabolites, such as acetate and sucrose, can be divided into two groups. The concentrations of these fermentation cycle metabolites were lower in CR and Singapore Kikkoman (SK, whereas much higher in Japanese shoyu (JS and Taiwan (China light (TL, which depict the influence of climatic conditions. Therefore, the results of our study directly indicate the influences of traditional ways of fermentation, climatic conditions and the selection of raw materials and can be helpful for consumers to choose their desired soy sauce products, as well as for researchers in further authentication studies about soy sauce.

  18. [sup 13]C NMR on C[sub 60] single-crystal. RMN du [sup 13]C sur un monocristal de C[sub 60

    Energy Technology Data Exchange (ETDEWEB)

    Kerkoud, R.; Auban-Senzier, P.; Godard, J.; Jerome, D. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique des Solides); Lambert, J.M.; Bernier, P. (Montpellier-1 Univ., 34 (France))

    1994-01-01

    The authors report a [sup 13]C NMR study performed on a C[sub 60] single crystal (8% enriched in [sup 13]C) grown by sublimation. Molecular motions are tested by spin-lattice relaxation data and spectral shapes below and above the structural transition at T[sub c] = 262 K. The sharpness of this transition and the long relaxation times at low temperature, compared to previous data on powdered samples, confirm the high purity of the crystal.

  19. Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR.

    Science.gov (United States)

    Hubert, Jane; Nuzillard, Jean-Marc; Purson, Sylvain; Hamzaoui, Mahmoud; Borie, Nicolas; Reynaud, Romain; Renault, Jean-Hugues

    2014-03-18

    Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside. PMID:24555703

  20. 13C-NMR Data of Diterpenes Isolated from Aristolochia Species

    Directory of Open Access Journals (Sweden)

    Antônio Flávio de Carvalho Alcântara

    2009-03-01

    Full Text Available The genus Aristolochia,an important source of physiologically active compounds that belong to different chemical classes, is the subject of research in numerous pharmacological and chemical studies. This genus contains a large number of terpenoid compounds, particularly diterpenes. This work presents a compilation of the 13C-NMR data of 57 diterpenoids described between 1981 and 2007 which were isolated from Aristolochia species. The compounds are arranged skeletonwise in each section, according to their structures, i.e., clerodane, labdane, and kaurane derivatives. A brief discussion on the 13C chemical shifts of these diterpenes is also included.

  1. Determination of fructose metabolic pathways in normal and fructose-intolerant children: A sup 13 C NMR study using (U- sup 13 C)fructose

    Energy Technology Data Exchange (ETDEWEB)

    Gopher, A.; Lapidot, A. (Weizmann Institute of Science, Rehovot (Israel)); Vaisman, N. (Kaplan Hospital, Rehovot (Israel)); Mandel, H. (Rambam Hospital, Haifa (Israel))

    1990-07-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-(U-{sup 13}C)fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of {sup 13}C NMR spectra of plasma glucose. Significantly lower values ({approx}3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from {sup 13}C NMR measurement of plasma ({sup 13}C)glucose isotopomer populations. The finding of isotopomer populations of three adjacent {sup 13}C atoms at glucose C-4 ({sup 13}C{sub 3}-{sup 13}C{sub 4}-{sup 13}C{sub 5}) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only {approx}50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of ({sup 13}C)glucose formation from a trace amount of (U-{sup 13}C)fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism.

  2. 1H-13C NMR-based profiling of biotechnological starch utilization

    DEFF Research Database (Denmark)

    Sundekilde, Ulrik K.; Meier, Sebastian

    2016-01-01

    Starch is used in food-and non-food applications as a renewable and degradable source of carbon and energy. Insight into the chemical detail of starch degradation remains challenging as the starch constituents amylose and amylopectin are homopolymers. We show that considerable molecular detail of......-resolution 1H-13C NMR spectroscopic profiles of homooligomeric fragment mixtures in conjunction with chemometric methods provide a useful addition to the analytical chemistry toolbox of biotechnologi-cal starch utilization....

  3. 13C high resolution solid state NMR spectra of Chinese coals

    Institute of Scientific and Technical Information of China (English)

    陈德玉; 胡建治; 叶朝辉

    1997-01-01

    Several typical exinites in China including alginite, cultinite, suberinite and bituminite are analysed by means of 13C high solution solid state CP MAS TOSS NMR spectra to determine their chemical structures and hydrocarbon potential. Thermal simulation solid products (TSSP) of hydrogen-rich coals arc studied to discuss the generation and expulsion mechanism of coal-generating hydrocarbon. The preliminary results are quite encouraging, containing useful information about genesis of coal-generating oil and gases.

  4. Quantifying the chemical composition of soil organic carbon with solid-state 13C NMR

    Science.gov (United States)

    Baldock, J. A.; Sanderman, J.

    2011-12-01

    The vulnerability of soil organic carbon (SOC) to biological decomposition and mineralisation to CO2 is defined at least partially by its chemical composition. Highly aromatic charcoal-like SOC components are more stable to biological decomposition than other forms of carbon including cellulose. Solid-state 13C NMR has gained wide acceptance as a method capable of defining SOC chemical composition and mathematical fitting processes have been developed to estimate biochemical composition. Obtaining accurate estimates depends on an ability to quantitatively detect all carbon present in a sample. Often little attention has been paid to defining the proportion of organic carbon present in a soil that is observable in solid-state 13C NMR analyses of soil samples. However, if such data is to be used to inform carbon cycling studies, it is critical that quantitative assessments of SOC observability be undertaken. For example, it is now well established that a significant discrimination exists against the detection of the low proton content polyaromatic structures typical of charcoal using cross polarisation 13C NMR analyses. Such discrimination does not exist where direct polarisation analyses are completed. In this study, the chemical composition of SOC as defined by cross polarisation and direct polarisation13C NMR analyses will be compared for Australian soils collected from under a diverse range of agricultural managements and climatic conditions. Results indicate that where significant charcoal C contents exist, it is highly under-represented in the acquired CP spectra. For some soils, a discrimination against alkyl carbon was also evident. The ability to derive correction factors to compensate for such discriminations will be assessed and presented.

  5. Using Neural Networks for 13C NMR Chemical Shift Prediction-Comparison with Traditional Methods

    Science.gov (United States)

    Meiler, Jens; Maier, Walter; Will, Martin; Meusinger, Reinhard

    2002-08-01

    Interpretation of 13C chemical shifts is essential for structure elucidation of organic molecules by NMR. In this article, we present an improved neural network approach and compare its performance to that of commonly used approaches. Specifically, our recently proposed neural network ( J. Chem. Inf. Comput. Sci. 2000, 40, 1169-1176) is improved by introducing an extended hybrid numerical description of the carbon atom environment, resulting in a standard deviation (std. dev.) of 2.4 ppm for an independent test data set of ˜42,500 carbons. Thus, this neural network allows fast and accurate 13C NMR chemical shift prediction without the necessity of access to molecule or fragment databases. For an unbiased test dataset containing 100 organic structures the accuracy of the improved neural network was compared to that of a prediction method based on the HOSE code ( hierarchically ordered spherical description of environment) using S PECI NFO. The results show the neural network predictions to be of quality (std. dev.=2.7 ppm) comparable to that of the HOSE code prediction (std. dev.=2.6 ppm). Further we compare the neural network predictions to those of a wide variety of other 13C chemical shift prediction tools including incremental methods (C HEMD RAW, S PECT OOL), quantum chemical calculation (G AUSSIAN, C OSMOS), and HOSE code fragment-based prediction (S PECI NFO, ACD/CNMR, P REDICTI T NMR) for the 47 13C-NMR shifts of Taxol, a natural product including many structural features of organic substances. The smallest standard deviations were achieved here with the neural network (1.3 ppm) and S PECI NFO (1.0 ppm).

  6. Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

    Science.gov (United States)

    Tossell, J. A.

    1995-04-01

    13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

  7. Histidine side-chain dynamics and protonation monitored by {sup 13}C CPMG NMR relaxation dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Hass, Mathias A. S. [Leiden University, Institute of Chemistry (Netherlands); Yilmaz, Ali [University of Copenhagen, Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences (Denmark); Christensen, Hans E. M. [Technical University of Denmark, Department of Chemistry (Denmark); Led, Jens J. [University of Copenhagen, Department of Chemistry (Denmark)], E-mail: led@kiku.dk

    2009-08-15

    The use of {sup 13}C NMR relaxation dispersion experiments to monitor micro-millisecond fluctuations in the protonation states of histidine residues in proteins is investigated. To illustrate the approach, measurements on three specifically {sup 13}C labeled histidine residues in plastocyanin (PCu) from Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for {sup 13}C{sup {epsilon}}{sup 1} nuclei in the histidine imidazole rings of A.v. PCu. The chemical shift changes obtained from the CPMG dispersion data are in good agreement with those obtained from the chemical shift titration experiments, and the CPMG derived exchange rates agree with those obtained previously from {sup 15}N backbone relaxation measurements. Compared to measurements of backbone nuclei, {sup 13}C{sup {epsilon}}{sup 1} dispersion provides a more direct method to monitor interchanging protonation states or other kinds of conformational changes of histidine side chains or their environment. Advantages and shortcomings of using the {sup 13}C{sup {epsilon}}{sup 1} dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains are discussed.

  8. Multidimensional High-Resolution Magic Angle Spinning and Solution-State NMR Characterization of (13)C-labeled Plant Metabolites and Lignocellulose.

    Science.gov (United States)

    Mori, Tetsuya; Tsuboi, Yuuri; Ishida, Nobuhiro; Nishikubo, Nobuyuki; Demura, Taku; Kikuchi, Jun

    2015-01-01

    Lignocellulose, which includes mainly cellulose, hemicellulose, and lignin, is a potential resource for the production of chemicals and for other applications. For effective production of materials derived from biomass, it is important to characterize the metabolites and polymeric components of the biomass. Nuclear magnetic resonance (NMR) spectroscopy has been used to identify biomass components; however, the NMR spectra of metabolites and lignocellulose components are ambiguously assigned in many cases due to overlapping chemical shift peaks. Using our (13)C-labeling technique in higher plants such as poplar samples, we demonstrated that overlapping peaks could be resolved by three-dimensional NMR experiments to more accurately assign chemical shifts compared with two-dimensional NMR measurements. Metabolites of the (13)C-poplar were measured by high-resolution magic angle spinning NMR spectroscopy, which allows sample analysis without solvent extraction, while lignocellulose components of the (13)C-poplar dissolved in dimethylsulfoxide/pyridine solvent were analyzed by solution-state NMR techniques. Using these methods, we were able to unambiguously assign chemical shifts of small and macromolecular components in (13)C-poplar samples. Furthermore, using samples of less than 5 mg, we could differentiate between two kinds of genes that were overexpressed in poplar samples, which produced clearly modified plant cell wall components. PMID:26143886

  9. Complete 1H and 13C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

    International Nuclear Information System (INIS)

    A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- (1H NMR, {1H} -13C NMR, and APT-13C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete 1H and 13C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated. (author)

  10. Characterizing crystal disorder of trospium chloride: a comprehensive,(13) C CP/MAS NMR, DSC, FTIR, and XRPD study.

    Science.gov (United States)

    Urbanova, Martina; Sturcova, Adriana; Brus, Jiri; Benes, Hynek; Skorepova, Eliska; Kratochvil, Bohumil; Cejka, Jan; Sedenkova, Ivana; Kobera, Libor; Policianova, Olivia; Sturc, Antonin

    2013-04-01

    Analysis of C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and X-ray powder diffraction data of trospium chloride (TCl) products crystallized from different mixtures of water-ethanol [φ(EtOH) = 0.5-1.0] at various temperatures (0°C, 20°C) and initial concentrations (saturated solution, 30%-50% excess of solvent) revealed extensive structural variability of TCl. Although (13) C CP/MAS NMR spectra indicated broad variety of structural phases arising from molecular disorder, temperature-modulated DSC identified presence of two distinct components in the products. FTIR spectra revealed alterations in the hydrogen bonding network (ionic hydrogen bond formation), whereas the X-ray diffraction reflected unchanged unit cell parameters. These results were explained by a two-component character of TCl products in which a dominant polymorphic form is accompanied by partly separated nanocrystalline domains of a secondary phase that does not provide clear Bragg reflections. These phases slightly differ in the degree of molecular disorder, in the quality of crystal lattice and hydrogen bonding network. It is also demonstrated that, for the quality control of such complex products, (13) C CP/MAS NMR spectroscopy combined with factor analysis (FA) can satisfactorily be used for categorizing the individual samples: FA of (13) C CP/MAS NMR spectra found clear relationships between the extent of molecular disorder and crystallization conditions. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1235-1248, 2013.

  11. Spectral editing for in vivo 13C magnetic resonance spectroscopy

    Science.gov (United States)

    Xiang, Yun; Shen, Jun

    2012-01-01

    In vivo detection of carboxylic/amide carbons is a promising technique for studying cerebral metabolism and neurotransmission due to the very low RF power required for proton decoupling. In the carboxylic/amide region, however, there is severe spectral overlap between acetate C1 and glutamate C5, complicating studies that use acetate as an astroglia-specific substrate. There are no known in vivo MRS techniques that can spectrally resolve acetate C1 and glutamate C5 singlets. In this study, we propose to spectrally separate acetate C1 and glutamate C5 by a two-step J-editing technique after introducing homonuclear 13C- 13C scalar coupling between carboxylic/amide carbons and aliphatic carbons. By infusing [1,2- 13C 2]acetate instead of [1- 13C]acetate the acetate doublet can be spectrally edited because of the large separation between acetate C2 and glutamate C4 in the aliphatic region. This technique can be applied to studying acetate transport and metabolism in brain in the carboxylic/amide region without spectral interference.

  12. Evaluating pyrolysis-GC/MS and 13C CPMAS NMR in conjunction with a molecular mixing model of the Penido Vello peat deposit, NW Spain

    NARCIS (Netherlands)

    Kaal, J.; Baldock, J.A.; Buurman, P.; Nierop, K.G.J.; Pontevedra-Pombal, X.; Martínez-Cortizas, A.

    2007-01-01

    We performed solid state 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy and pyrolysis¿gas chromatography/mass spectrometry (Py¿GC/MS) on the Penido Vello peat deposit located in Galicia, NW Spain. Often regarded as complementary techniques, solid st

  13. Solid state 13C NMR studies of methane dehydroaromatization reaction on Mo/HZSM-5 and W/HZSM-5 catalysts.

    Science.gov (United States)

    Yang, Jun; Ma, Ding; Deng, Feng; Luo, Qing; Zhang, Mingjin; Bao, Xinhe; Ye, Chaohui

    2002-12-21

    Methane dehydroaromatization on Mo/HZSM-5 and W/HZSM-5 catalysts was studied by solid state 13C NMR spectroscopy, both variation of the state of transition metal component and products such as ethane, benzene, ethene adsorbed on or in zeolite were observed after high temperature (900-1000 K) reaction.

  14. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    Science.gov (United States)

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom. PMID:26670708

  15. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    Science.gov (United States)

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

  16. Data of 1H/13C NMR spectra and degree of substitution for chitosan alkyl urea

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2016-06-01

    Full Text Available The data shown in this article are related to the subject of an article in Carbohydrate Polymers, entitled “Synthesis and characterization of chitosan alkyl urea” [1]. 1H NMR and 13C NMR spectra of chitosan n-octyl urea, chitosan n-dodecyl urea and chitosan cyclohexyl urea are displayed. The chemical shifts of proton and carbon of glucose skeleton in these chitosan derivatives are designated in detail. Besides, 1H NMR spectra of chitosan cyclopropyl urea, chitosan tert-butyl urea, chitosan phenyl urea and chitosan N,N-diethyl urea and the estimation of the degree of substitution are also presented. The corresponding explanations can be found in the above-mentioned article.

  17. Single voxel localization for dynamic hyperpolarized 13C MR spectroscopy

    Science.gov (United States)

    Chen, Albert P.; Cunningham, Charles H.

    2015-09-01

    The PRESS technique has been widely used to achieve voxel localization for in vivo1H MRS acquisitions. However, for dynamic hyperpolarized 13C MRS experiments, the transition bands of the refocusing pulses may saturate the pre-polarized substrate spins flowing into the voxel. This limitation may be overcome by designing refocusing pulses that do not perturb the resonance of the hyperpolarized substrate, but selectively refocuses the spins of the metabolic products. In this study, a PRESS pulse sequence incorporating spectral-spatial refocusing pulses that have a stop band ('notch') at the substrate resonance is tested in vivo using hyperpolarized [1-13C]pyruvate. Higher metabolite SNR was observed in experiments using the spectral-spatial refocusing pulses as compared to conventional refocusing pulses.

  18. Dynamic 13C NMR analysis of oxidative metabolism in the in vivo canine myocardium.

    Science.gov (United States)

    Robitaille, P M; Rath, D P; Abduljalil, A M; O'Donnell, J M; Jiang, Z; Zhang, H; Hamlin, R L

    1993-12-15

    Oxidative metabolism in the in vivo canine myocardium was studied noninvasively using 13C-enriched acetate and non-steady state 13C NMR techniques. Under low workload conditions, the myocardium oxidized the infused [2-13C]acetate and incorporated the labeled carbon into the glutamate pool as expected. This conclusion stems from the rapid enrichment of the C-2, C-3, and C-4 carbons of glutamic acid both under in vivo conditions and in extracts. Surprisingly, [2-13C]acetate uptake was not observed at high workloads as reflected by an absence of glutamate pool enrichment at these rate pressure products. Rather, the myocardium selected its substrate from an endogenous pool. Since free acetate can directly cross the inner mitochondrial membrane and be converted to acetyl-CoA through acetyl-CoA synthetase, these results support workload-dependent regulation of substrate access to the mitochondrial CoASH pool. As such, we advance the hypothesis that the selection of substrate for condensation with CoASH and subsequent oxidation in the tricarboxylic acid cycle is regulated kinetically through the Km values of the appropriate condensation enzymes and through the absolute levels of free CoASH in the mitochondria. PMID:8253751

  19. Determination of fructose metabolic pathways in normal and fructose-intolerant children: a 13C NMR study using [U-13C]fructose.

    OpenAIRE

    Gopher, A; Vaisman, N; Mandel, H.; Lapidot, A

    1990-01-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-[U-13C]fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of 13C NMR spectra of plasma glucose....

  20. sup 13 C and sup 31 P NMR studies of myocardial metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Laughlin, M.R.

    1988-01-01

    The fluxes through two enzyme systems have been measured in perfused or in in vivo heart using NMR: phosphocreatine kinase, and glycogen synthase and phosphorylase. The rates of synthesis and degradation of glycogen were monitored in vivo in fed, fasted, and diabetic rat heart during infusions of {sup 13}C-1-glucose and insulin using proton-decoupled {sup 13}C-NMR at 1.9 and 4.7 tesla. The enzyme activities of glycogen synthase and glycogen phosphorylase were also measured in this tissue which had been freeze clamped at the end of the experiment, for comparison with the synthetic rates. For normal fed, fasted, and diabetic animals, synthesis rates were 0.28, 0.16, and 0.15 {mu}mol/min.gww respectively. Glycogen synthase i activity was 0.23, 0.14, and 0.14 {mu}mol/min.gww in these hearts at the end of the experiment, when measured at appropriate substrate and activator concentrations, and follow activation time courses that are consistent with being the main rate determinant for net synthesis in all cases. Turnover of glycogen was studied by observing the preformed {sup 13}C-1-glycogen signal during infusion of {sup 12}C-glucose and insulin, and was found to be close to zero. Extracted phosphorylase a activity was approximately ten times that of synthase i under these circumstances. In order to fully interpret the turnover studies, glycogenolysis of preformed {sup 13}C-glycogen was observed after a bolus of glucagon. The glycogen had either been synthesized from {sup 13}C-1-glucose for a single hour, or during an hour of {sup 13}C-glucose and a subsequent hour of {sup 12}C-glucose infusion. The author observed that breakdown follows an exponential time course related to the phosphorylase a activation state and that the last synthesized glycogen breaks down at the rate of 2.5 {mu}mol/min.gww, five times faster than that synthesized an hour earlier.

  1. The binding of metal ions and angiotensin converting enzyme (ACE) inhibitor by 13C NMR

    Science.gov (United States)

    Sakamoto, Yohko; Sakamoto, Yuko; Ishii, Tomoko; Ohmoto, Taichi

    1991-06-01

    Enalaprilat (MK-422, 1- [ N- [1 (S)-carboxy-3-phenylpropyl]- L-alanyl]- L-proline (1)) and Lisinopril (MK521, N- N- [ (s)-l-carboxy-3- phenylpropyl]- L-lysyl- L-proline, (2)) exhibit the capacity to act as a chelate, unidentate or bridge towards metal ions in aqueous solution, as determined by 13C NMR. By adding metal ions, in the series of Zn 2+, Ni 2+, Pb 2+, Pd 2+ and Cd 2+, the active site of the ACE inhibitor was well defined. MK-521 was more influenced by nuclei that were distant from the active site than MK-422.

  2. STUDY ON SEQUENCE STRUCTURE OF ACRYLAMIDE-ACRYLATE COPOLYMERS BY 13C-NMR METHOD

    Institute of Scientific and Technical Information of China (English)

    YUAN Dongwu; ZHU Shannong; YANG Xiaozhen

    1987-01-01

    Triad sequence distributions in a series of P(AM/AA) with different AA% were calculated from copolymerization reactivity ratio r1 and r2 based on first order Markov statistic model, and the calculated data compared with observed ones from 13C-NMR spectra showed good agreement with each other, The sequence distribution in P(AM/AA) obtained under our experimental conditions fits in with first order Markov statistic model. A significant sequence structure difference was observed between P(AM/AA) and alkaline hydrolyzed polyacrylamide, ABA triad (acrylate unit center), AAA and AAB triads (acrylamide unit center) dominated in hydrolyzed ones.

  3. International symposium on NMR spectroscopy

    International Nuclear Information System (INIS)

    The publication consists of 32 papers and presentations from the field of NMR spectroscopy applications submitted to the International Symposium on NMR Spectroscopy held at Smolenice between 29 Sep and 3 Oct, 1980. (B.S.)

  4. Structure and equilibria of Ca 2+-complexes of glucose and sorbitol from multinuclear ( 1H, 13C and 43Ca) NMR measurements supplemented with molecular modelling calculations

    Science.gov (United States)

    Pallagi, A.; Dudás, Cs.; Csendes, Z.; Forgó, P.; Pálinkó, I.; Sipos, P.

    2011-05-01

    Ca 2+-complexation of D-glucose and D-sorbitol have been investigated with the aid of multinuclear ( 1H, 13C and 43Ca) NMR spectroscopy and ab initio quantum chemical calculations. Formation constants of the forming 1:1 complexes have been estimated from one-dimensional 13C NMR spectra obtained at constant ionic strength (1 M NaCl). Binding sites were identified from 2D 1H- 43Ca NMR spectra. 2D NMR measurements and ab initio calculations indicated that Ca 2+ ions were bound in a tridentate manner via the glycosidic OH, the ethereal oxygen in the ring and the OH on the terminal carbon for the α- and β-anomers of glucose and for sorbitol simultaneous binding of four hydroxide moieties (C1, C2, C4 and C6) was suggested.

  5. Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

    Directory of Open Access Journals (Sweden)

    Mohamed Haouas

    2016-06-01

    Full Text Available The dynamic behavior of tetrapropylammonium (TPA cations in the clear precursor sols for silicalite synthesis has been investigated by 1H diffusion ordered spectroscopy (DOSY, T1, T2, and T1ρ 1H relaxation, as well as 1H→13C cross polarization (CP nuclear magnetic resonance. The DOSY NMR experiments showed the presence of strong solute–solvent interactions in concentrated sols, which are decreasing upon dilution. Similarities in dependence of diffusion coefficients with fractional power of the viscosity constant observed for nanoparticles, TPA cations and water led to the conclusion that they aggregate as anisotropic silicate-TPA particles. Relaxation studies as well as 1H→13C CP experiments provide information on dynamic properties of ethanol, water and TPA cations, which are function of silicate aggregates. The general tendency showed that the presence of silicate as oligomers and particles decreases the relaxation times, in particular T2 and T1ρH, as a consequence of involvement of these latter in ion-pairing interactions with water-solvated TPA molecules slowing down their mobility. Furthermore, from the 1H→13C CP dynamics curve profiles a change in the CP transfer regime was observed from fast (TCH << T1ρH for solutions without silicates to moderate (TCH~T1ρH when silicates are interacting with the TPA cations that may reflect the occlusion of TPA into flexible silicate hydrate aggregates.

  6. NMR study of the 1-{sup 13}C glucose colon bacterial metabolism; Etude du metabolisme bacterien colique du 1-{sup 13}C glucose par RMN

    Energy Technology Data Exchange (ETDEWEB)

    Briet, F.; Flourie, B.; Pochart, P.; Rambaud, J.C.; Desjeux, J.F. [Hopital Saint-Lazare, 75 - Paris (France); Dallery, L. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France); Grivet, J.P. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France)

    1994-12-31

    The aim of the study is to examine in-vitro and by nuclear magnetic resonance the biological pathways for the fermentation of the 1-{sup 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.

  7. Total assignment of 1H and 13C NMR data for the sesquiterpene lactone 15-deoxygoyazensolide.

    Science.gov (United States)

    Heleno, Vladimir Constantino Gomes; Crotti, Antônio Eduardo Miller; Constantino, Mauricio Gomes; Lopes, Norberto Peporine; Lopes, João Luis Callegari

    2004-03-01

    We describe a complete analysis of the 1H and 13C spectra of the anti-inflamatory, schistossomicidal and trypanosomicidal sesquiterpene lactone 15-deoxygoyazensolide. This lactone, with a structure similar to other important ones, was studied by NMR techniques such as COSY, HMQC, HMBC, Jres and NOE experiments. The comparison of the data with some computational results led to an unequivocal assignment of all hydrogen and carbon chemical shifts, even eliminating some previous ambiguities. We were able to determine all hydrogen coupling constants (J) and signal multiplicities and to confirm the stereochemistry. A new method for the determination of the relative position of the lactonization and the position of the ester group on a medium-sized ring by NMR was developed.

  8. 1H, 13C and 15N NMR assignments of phenazopyridine derivatives.

    Science.gov (United States)

    Burgueño-Tapia, Eleuterio; Mora-Pérez, Yolanda; Morales-Ríos, Martha S; Joseph-Nathan, Pedro

    2005-03-01

    Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional (1)H, (13)C and (15)N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the (15)N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry. PMID:15625718

  9. (13)C NMR characterization of triacylglycerols of Moringa oleifera seed oil: an "oleic-vaccenic acid" oil.

    Science.gov (United States)

    Vlahov, Giovanna; Chepkwony, Paul Kiprono; Ndalut, Paul K

    2002-02-27

    The composition of acyl chains and their positions in the triacylglycerols of the oil extracted from seeds of Moringa oleifera were studied by (13)C NMR spectroscopy. The unsaturated chains of M. oleifera seed oil were found to comprise only mono-unsaturated fatty acids and, in particular, two omega-9 mono-unsaturated acids, (cis-9-octadecenoic (oleic acid) and cis-11-eicosenoic acids) and one omega-7 mono-unsaturated acid (cis-11-octadecenoic acid (vaccenic acid)). The mono-unsaturated fatty acids were detected as separated resonances in the spectral regions where the carbonyl and olefinic carbons resonate according to the 1,3- and 2-positions on the glycerol backbone. The unambiguous detection of vaccenic acid was also achieved through the resonance of the omega-3 carbon. The (13)C NMR methodology enabled the simultaneous detection of oleate, vaccenate, and eicosenoate chains according to their positions on the glycerol backbone (1,3- and 2-positions) through the carboxyl, olefinic, and methylene envelope carbons of the triacylglycerol acyl chains. PMID:11853466

  10. Molecular structure, vibrational and 13C NMR spectra of two ent-kaurenes spirolactone type diterpenoids rabdosinate and rabdosin B: A combined experimental and density functional methods

    Science.gov (United States)

    Wang, Tao; Wang, Xueliang

    2015-01-01

    The title compounds, rabdosinate and rabdosin B, were isolated from the leaves of Isodon japonica, and characterized by IR-NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO-13C) chemical shift values of the title compounds have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set. In addition, obtained results were related to the linear regression of experimental 13C NMR chemical shifts values. The integral equation formalism polarized continuum model (IEFPCM) was used in treating chloroform solvation effects on optimized structural parameters and 13C chemical shifts. Besides, molecular electrostatic potential (MEP), HOMO-LUMO analysis were performed by the B3LYP method.

  11. Sensitivity-enhanced 13C MR spectroscopy of the human brain at 3 Tesla.

    NARCIS (Netherlands)

    Klomp, D.W.J.; Renema, W.K.J.; Graaf, M. van der; Galan, B.E. de; Kentgens, A.P.M.; Heerschap, A.

    2006-01-01

    A new coil design for sensitivity-enhanced 13C MR spectroscopy (MRS) of the human brain is presented. The design includes a quadrature transmit/receive head coil optimized for 13C MR sensitivity. Loss-less blocking circuits inside the coil conductors allow this coil to be used inside a homogeneous c

  12. Identification of aquatically available carbon from algae through solution-state NMR of whole (13)C-labelled cells.

    Science.gov (United States)

    Akhter, Mohammad; Dutta Majumdar, Rudraksha; Fortier-McGill, Blythe; Soong, Ronald; Liaghati-Mobarhan, Yalda; Simpson, Myrna; Arhonditsis, George; Schmidt, Sebastian; Heumann, Hermann; Simpson, André J

    2016-06-01

    Green algae and cyanobacteria are primary producers with profound impact on food web functioning. Both represent key carbon sources and sinks in the aquatic environment, helping modulate the dissolved organic matter balance and representing a potential biofuel source. Underlying the impact of algae and cyanobacteria on an ecosystem level is their molecular composition. Herein, intact (13)C-labelled whole cell suspensions of Chlamydomonas reinhardtii, Chlorella vulgaris and Synechocystis were studied using a variety of 1D and 2D (1)H/(13)C solution-state nuclear magnetic resonance (NMR) spectroscopic experiments. Solution-state NMR spectroscopy of whole cell suspensions is particularly relevant as it identifies species that are mobile (dissolved or dynamic gels), 'aquatically available' and directly contribute to the aquatic carbon pool upon lysis, death or become a readily available food source on consumption. In this study, a wide range of metabolites and structural components were identified within the whole cell suspensions. In addition, significant differences in the lipid/triacylglyceride (TAG) content of green algae and cyanobacteria were confirmed. Mobile species in algae are quite different from those in abundance in 'classic' dissolved organic matter (DOM) indicating that if algae are major contributors to DOM, considerable selective preservation of minor components (e.g. sterols) or biotransformation would have to occur. Identifying the metabolites and dissolved components within algal cells by NMR permits future studies of carbon transfer between species and through the food chain, whilst providing a foundation to better understand the role of algae in the formation of DOM and the sequestration/transformation of carbon in aquatic environments. PMID:27074782

  13. Evidencing of collagen polypeptide sequences responsible of hydration by means of 13 C NMR spectra

    International Nuclear Information System (INIS)

    The aim of these studies is to prepare biomaterials of high biocompatibility to the human body, provided for a long lifetime. Among these important biomaterials also accounts the collagen, with a large application area in medicine, pharmaceutics, cosmetics, etc. Collagen biomaterials of various hydration levels (between 23 - 83%) were prepared by a particular technique, using a matrix of 23% initial humidity. In order to investigate the structural and conformational changes from the collagen macromolecules by denaturation - renaturation, hydration - dehydration, the high-resolution 13 C - NMR solid state and also pore size distribution analysis were carried out. The collagen biomaterials can be made in a large range of shapes and can have structures of mimesis, close to those of the live tissues, when hydrated. (authors)

  14. {sup 13}C NMR spectral data and molecular descriptors to predict the antioxidant activity of flavonoids

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Mariane Balerine; Muramatsu, Eric [Universidade de Sao Paulo (USP). Ribeirao Preto, SP (Brazil). Fac. de Ciencias Farmauceuticas; Emereciano, Vicente de Paula [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Scotti, Marcus Tullius [Universidade Federal da Paraiba (UFPA), Joao Pessoa, PA (Brazil). Centro de Ciencias Aplicadas e Educacao; Scotti, Luciana; Tavares, Josean Fechine; Silva, Marcelo Sobral da [Universidade Federal da Paraiba (UFPA), Joao Pessoa, PA (Brazil). Lab. de Tecnologia Farmaceutica

    2011-04-15

    Tissue damage due to oxidative stress is directly linked to development of many, if not all, human morbidity factors and chronic diseases. In this context, the search for dietary natural occurring molecules with antioxidant activity, such as flavonoids, has become essential. In this study, we investigated a set of 41 flavonoids (23 flavones and 18 flavonols) analyzing their structures and biological antioxidant activity. The experimental data were submitted to a QSAR (quantitative structure-activity relationships) study. NMR {sup 13}C data were used to perform a Kohonen self-organizing map study, analyzing the weight that each carbon has in the activity. Additionally, we performed MLR (multilinear regression) using GA (genetic algorithms) and molecular descriptors to analyze the role that specific carbons and substitutions play in the activity. (author)

  15. Acetate and bicarbonate assimilation and metabolite formation in Chlamydomonas reinhardtii: a 13C-NMR study.

    Directory of Open Access Journals (Sweden)

    Himanshu Singh

    Full Text Available Cellular metabolite analyses by (13C-NMR showed that C. reinhardtii cells assimilate acetate at a faster rate in heterotrophy than in mixotrophy. While heterotrophic cells produced bicarbonate and CO2aq, mixotrophy cells produced bicarbonate alone as predominant metabolite. Experiments with singly (13C-labelled acetate ((13CH(3-COOH or CH(3-(13COOH supported that both the (13C nuclei give rise to bicarbonate and CO2(aq. The observed metabolite(s upon further incubation led to the production of starch and triacylglycerol (TAG in mixotrophy, whereas in heterotrophy the TAG production was minimal with substantial accumulation of glycerol and starch. Prolonged incubation up to eight days, without the addition of fresh acetate, led to an increased TAG production at the expense of bicarbonate, akin to that of nitrogen-starvation. However, such TAG production was substantially high in mixotrophy as compared to that in heterotrophy. Addition of mitochondrial un-coupler blocked the formation of bicarbonate and CO2(aq in heterotrophic cells, even though acetate uptake ensued. Addition of PSII-inhibitor to mixotrophic cells resulted in partial conversion of bicarbonate into CO2(aq, which were found to be in equilibrium. In an independent experiment, we have monitored assimilation of bicarbonate via photoautotrophy and found that the cells indeed produce starch and TAG at a much faster rate as compared to that in mixotrophy and heterotrophy. Further, we noticed that the accumulation of starch is relatively more as compared to TAG. Based on these observations, we suggest that acetate assimilation in C. reinhardtii does not directly lead to TAG formation but via bicarbonate/CO2(aq pathways. Photoautotrophic mode is found to be the best growth condition for the production of starch and TAG and starch in C. reinhardtii.

  16. Complete 1H and 13C NMR structural assignments for a group of four goyazensolide-type furanoheliangolides

    International Nuclear Information System (INIS)

    Four goyazensolide-type sesquiterpene lactones - lychnofolide, centratherin, goyazensolide and goyazensolide acetate - were thoroughly studied by NMR experimental techniques. 1H NMR, 13C NMR {1H}, COSY, HMQC, HMBC, J-res. and NOE experiments were performed to provide the needed structural information. Complete and unequivocal assignment, including the determination of all multiplicities, was obtained for each structure and the data collections are presented in tables (author)

  17. Complete {sup 1}H and {sup 13}C NMR structural assignments for a group of four goyazensolide-type furanoheliangolides

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Ana Carolina Ferreira; Silva, Aline Nazare; Matos, Priscilla Mendonca; Silva, Eder Henrique da; Heleno, Vladimir Constantino Gomes [Universidade de Franca, Franca, SP (Brazil). Nucleo de Pesquisas em Ciencias Exatas e Tecnologicas; Lopes, Norberto Peporine; Lopes, Joao Luis Callegari [Universidade de Sao Paulo (FCFRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Ciencias Farmaceuticas de Ribeirao Preto. Dept. de Quimica e Fisica; Sass, Daiane Cristina, E-mail: vheleno_05@yahoo.com.br [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Filosofia, Ciencias e Letras de Ribeirao Preto. Dept. de Quimica

    2012-07-01

    Four goyazensolide-type sesquiterpene lactones - lychnofolide, centratherin, goyazensolide and goyazensolide acetate - were thoroughly studied by NMR experimental techniques. {sup 1}H NMR, {sup 13}C NMR {l_brace}{sup 1}H{r_brace}, COSY, HMQC, HMBC, J-res. and NOE experiments were performed to provide the needed structural information. Complete and unequivocal assignment, including the determination of all multiplicities, was obtained for each structure and the data collections are presented in tables (author)

  18. Secondary structural analysis of proteins based on 13C chemical shift assignments in unresolved solid-state NMR spectra enhanced by fragmented structure database

    International Nuclear Information System (INIS)

    Magic-angle-spinning solid-state 13C NMR spectroscopy is useful for structural analysis of non-crystalline proteins. However, the signal assignments and structural analysis are often hampered by the signal overlaps primarily due to minor structural heterogeneities, especially for uniformly-13C,15N labeled samples. To overcome this problem, we present a method for assigning 13C chemical shifts and secondary structures from unresolved two-dimensional 13C–13C MAS NMR spectra by spectral fitting, named reconstruction of spectra using protein local structures (RESPLS). The spectral fitting was conducted using databases of protein fragmented structures related to 13Cα, 13Cβ, and 13C′ chemical shifts and cross-peak intensities. The experimental 13C–13C inter- and intra-residue correlation spectra of uniformly isotope-labeled ubiquitin in the lyophilized state had a few broad peaks. The fitting analysis for these spectra provided sequence-specific Cα, Cβ, and C′ chemical shifts with an accuracy of about 1.5 ppm, which enabled the assignment of the secondary structures with an accuracy of 79 %. The structural heterogeneity of the lyophilized ubiquitin is revealed from the results. Test of RESPLS analysis for simulated spectra of five different types of proteins indicated that the method allowed the secondary structure determination with accuracy of about 80 % for the 50–200 residue proteins. These results demonstrate that the RESPLS approach expands the applicability of the NMR to non-crystalline proteins exhibiting unresolved 13C NMR spectra, such as lyophilized proteins, amyloids, membrane proteins and proteins in living cells.

  19. In Situ 13C NMR at Elevated-Pressures and -Temperatures Investigating the Conversion of CO2 to Magnesium and Calcium Carbonate Minerals

    Science.gov (United States)

    Surface, J. A.; Conradi, M. S.; Skemer, P. A.; Hayes, S. E.

    2013-12-01

    We have constructed specialized NMR hardware to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies of unmixed heterogeneous mixtures of solids, liquids, gases, and supercritical fluids. Specifically, our aim is to monitor CO2 uptake in both ultramafic rocks and in more porous geological materials to understand the mechanisms of chemisorption as a function of temperature, pressure and pH. In this in situ NMR probe, we are able to simulate processes at geologically relevant fluid pressures and temperatures, monitoring the kinetics of CO2 conversion to carbonates. The in situ NMR experiments consist of heterogeneous mixtures of rock, salty brine solution, and moderate pressure CO2 gas at elevated temperatures. The purpose of studying these reactions is to determine efficacy of carbonate formation in various geological reservoirs. Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals. When CO2 reacts with the calcium or magnesium in a mineral or rock sample, the 13C chemical shift, linewidth, lineshape, and relaxation times change dramatically. This change can be monitored in situ and provide instantaneous and continuous characterization that maps the chemistry that is taking place. For example, on the pathway to MgCO3 formation, there are a number of phases of Mg(OH)x(H2O)y(CO3)z that are apparent via NMR spectroscopy. We will demonstrate that NMR can be used for quantitative characterization of multiple metastable mineral phases in pure forms and in mixtures. Results are confirmed via powder XRD and Raman spectroscopy of aquo- hydro- carbonato- magnesium species and calcium carbonate species. We also have monitored the 13C spectroscopy to analyze the phase of CO2 (liquid, supercritical, or gas) and its conversion into other forms, such as bicarbonate and carbonate species, providing a "window" into the in situ pH of the reacting system. Reference: 'In Situ

  20. Mono terpenes characterization by {sup 1} H and {sup 13} C-1 NMR; Caracterizacao de monoterpenos por RMN - {sup 1} H e de {sup 13} C-1

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Martha T. de [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Fisico-Quimica; Silveira, Carmen L.P. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Quimica Organica; Mcchesney, James D. [Mississippi Univ., University, MS (United States). Research Inst. of Pharmaceutical Sciences

    1991-12-31

    Artemisinine, a new lactone sesquiterpene containing one peroxide binding, is the main anti malarial agent obtained from the Artemisia annua L. Viewing to obtain a simple synthetic route for artemisinic acid preparation, which is the key intermediary for total synthesis of this type of anti malarial agent, R-carvone has been chosen as starting material. The S-carvone was used as model for reaction optimization and preparation of derivatives to be used for NMR studies. The main objective of this work is the signalling of the {sup 13} C and {sup 1} H NMR spectra, using the 2 D-COSY and 2 D-Hector spectra 4 refs., 3 figs., 1 tab

  1. Land use Effects on Storage, Stability and Structure of Organic Carbon in Soil Density Fractions Revealed by 13C Natural Abundance and CPMAS 13C NMR

    Science.gov (United States)

    Flessa, H.; Helfrich, M.; John, B.; Yamashita, T.; Ludwig, B.

    2004-12-01

    The type of land use and soil cultivation are important factors controlling organic carbon storage (SOC) in soils and they can also influence the relative importance, the structure, and the stability of different SOC pools. The objectives of our study were: i) to quantify the SOC stocks in different density fractions (mineral-associated soil organic matter > 2 g cm-3 (Mineral-SOM), free particulate organic matter soils under different land use (spruce forest, grassland, maize, wheat), ii) to determine the structure of these SOC fractions by CPMAS 13C NMR spectroscopy, and iii) to analyse the stability of these SOC fractions in the maize soil on the basis of the stable isotope composition of SOC. The SOC concentration in the A horizon increased in the order wheat (12.7 g kg-1) soil, the particulate organic matter accounted for 52% of the total SOC content. The chemical structure of the soil organic matter (SOM) was influenced by litter quality, the intensity of litter decomposition and the related production and storage of microbially-derived substances. SOM of the acid forest soil was characterized by large amounts of POM with a high content of spruce litter-derived alkyl C. In the biologically more active grassland and maize soil, litter-derived POM was decomposed more rapidly and SOC stocks were dominated by mineral-associated SOM which contained greater proportions of aryl and carbonyl C. The cultivation of the grassland soil induced enhanced mineralization of POM and in particular of mineral-associated SOM. The faster SOC turnover was associated with a relative accumulation of aromatic and carbonyl C structures in the mineral-bound SOM. In all soils, the free particulate organic matter had a smaller proportion of alkyl C and a larger proportion of O-alkyl C than the particulate organic matter occluded in aggregates. The mean age of the SOM in the density fractions of the maize soil increased with increasing aromaticity in the order free POM (22 yr) humification

  2. Radiation oxidation of polypropylene: A solid-state 13C NMR study using selective isotopic labeling

    International Nuclear Information System (INIS)

    Polypropylene samples, in which the three different carbon atoms along the chain were selectively labeled with carbon-13, were subjected to radiation under inert and air atmospheres, and to post-irradiation exposure in air at various temperatures. By using solid-state 13C NMR measurements at room temperature, we have been able to identify and quantify the oxidation products. The isotopic labeling provides insight into chemical reaction mechanisms, since oxidation products can be traced back to their positions of origin on the macromolecule. The major products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. Time-dependent plots of yields of the various oxidation products have been obtained under a wide range of conditions, including the post-irradiation oxidation of a sample at room temperature in air that has been monitored for 2 years. Radiation-oxidation products of polypropylene are contrasted to products measured for 13C-labeled polyethylene in an earlier investigation: the peroxides formed in irradiated polypropylene are remarkably longer lived, the non-peroxidic products are significantly different, and the overall ratios of oxidation products in polypropylene change relatively little as a function of the extent of oxidation

  3. Identification of archaeological triterpenic resins by the non-separative techniques FTIR and 13C NMR: the case of Pistacia resin (mastic) in comparison with frankincense.

    Science.gov (United States)

    Bruni, Silvia; Guglielmi, Vittoria

    2014-01-01

    The use of spectroscopic techniques such as Fourier-transform infrared (FTIR) spectroscopy and carbon 13 nuclear magnetic resonance ((13)C NMR) using the J-mod experiment is proposed as an effective alternative to gas chromatography-mass spectrometry (GC-MS) for the analysis and identification of natural resin samples found in archaeological environments. The spectral features of the most common diterpenic and triterpenic resins and also two gum-resins are reported and discussed for both techniques. The analytical procedure based on the combined use of FTIR and (13)C NMR is then applied to two archaeological samples from the Milano of the Roman age allowing their identification as Pistacia resin, or mastic, as confirmed by the traditional GC-MS method, and also elucidating some effects of aging on such material.

  4. Spectrally edited 2D 13Csbnd 13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials

    Science.gov (United States)

    Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

    2013-09-01

    Two robust combinations of spectral editing techniques with 2D 13Csbnd 13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, Csbnd H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and Cdbnd O carbons

  5. 500-fold enhancement of in situ 13C liquid state NMR using gyrotron-driven temperature-jump DNP

    Science.gov (United States)

    Yoon, Dongyoung; Soundararajan, Murari; Caspers, Christian; Braunmueller, Falk; Genoud, Jérémy; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-09-01

    A 550-fold increase in the liquid state 13C NMR signal of a 50 μL sample was obtained by first hyperpolarizing the sample at 20 K using a gyrotron (260 GHz), then, switching its frequency in order to apply 100 W for 1.5 s so as to melt the sample, finally, turning off the gyrotron to acquire the 13C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid 1H NMR signal.

  6. Metabolic Effects of Hypoxia in Colorectal Cancer by 13C NMR Isotopomer Analysis

    Directory of Open Access Journals (Sweden)

    Ana M. Abrantes

    2014-01-01

    Full Text Available 13C NMR isotopomer analysis was used to characterize intermediary metabolism in three colorectal cancer cell lines (WiDr, LS1034, and C2BBe1 and determine the “metabolic remodeling” that occurs under hypoxia. Under normoxia, the three colorectal cancer cell lines present high rates of lactate production and can be seen as “Warburg” like cancer cells independently of substrate availability, since such profile was dominant at both high and low glucose media contents. The LS1034 was the less glycolytic of the three cell lines and was the most affected by the event of hypoxia, raising abruptly glucose consumption and lactate production. The other two colorectal cell lines, WiDr and C2BBe1, adapted better to hypoxia and were able to maintain their oxidative fluxes even at the very low levels of oxygen. These differential metabolic behaviors of the three colorectal cell lines show how important an adequate knowledge of the “metabolic remodeling” that follows a given cancer treatment is towards the correct (redesign of therapeutic strategies against cancer.

  7. NMR studies of bent DNA using {sup 13}C-enriched samples

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, D.P.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

    1994-12-01

    Bending of the DNA double helix can be brought about by introducing runs of adenines (A-tracts) in phase with the helical repeat of the DNA. The requirements for bending of DNA by A-tracts are that the length of the A-tract be greater than 3 base pairs and that the A-tracts must be in phase with the helical repeat (every 10 or 11 bp). Other factors, such as the number of adenines in the run, flanking sequences, and whether the A-tracts are phased with respect to the 5{prime}A or the 3{prime}A, have effects upon the degree of bending as assayed by electrophoretic mobility on native polyacrylamide gels. There are a number of models for bending A-tract DNA. The junction-bending model postulates that the structure of A-tracts is similar to the fiber diffraction structure of poly A, in which there is a significant degree of base pair tilt with respect to the helix axis. In this model, bending occurs at the junction between the A-tract and the B-form helix to allow favorable stacking interactions to occur. The bend of the helix could arise as a result of some other perturbation of B-form DNA by A-tracts, such as propeller twist; bending also could be due to a combination of factors. Our goal is to find the structural features of A-tracts responsible for bending of the helix by performing NMR on oligonucleotides containing A-tracts to obtain higher resolution structural data. One of the problems encountered in NMR structure determination of nucleic acids and other macromolecules is the assignment of resonances to nuclei. This procedure can be greatly facilitated through the use of {sup 13}C-enriched nucleic acid samples. We are developing a technique for the enzymatic synthesis of labeled DNA for NMR. The technique we are developing is similar to RNA labeling techniques already in use. The technique involves growth of methylotrophic bacteria on {sup 13}CH{sub 3}OH.

  8. Real-time assessment of Krebs cycle metabolism using hyperpolarized 13C magnetic resonance spectroscopy.

    Science.gov (United States)

    Schroeder, Marie A; Atherton, Helen J; Ball, Daniel R; Cole, Mark A; Heather, Lisa C; Griffin, Julian L; Clarke, Kieran; Radda, George K; Tyler, Damian J

    2009-08-01

    The Krebs cycle plays a fundamental role in cardiac energy production and is often implicated in the energetic imbalance characteristic of heart disease. In this study, we measured Krebs cycle flux in real time in perfused rat hearts using hyperpolarized magnetic resonance spectroscopy (MRS). [2-(13)C]Pyruvate was hyperpolarized and infused into isolated perfused hearts in both healthy and postischemic metabolic states. We followed the enzymatic conversion of pyruvate to lactate, acetylcarnitine, citrate, and glutamate with 1 s temporal resolution. The appearance of (13)C-labeled glutamate was delayed compared with that of other metabolites, indicating that Krebs cycle flux can be measured directly. The production of (13)C-labeled citrate and glutamate was decreased postischemia, as opposed to lactate, which was significantly elevated. These results showed that the control and fluxes of the Krebs cycle in heart disease can be studied using hyperpolarized [2-(13)C]pyruvate.

  9. STUDY ON THE SEQUENCE STRUCTURE OF SBR BY 13C- NMR METHOD Ⅱ . PEAK ASSIGNMENT FOR ALIPHATIC CARBONS SPECTRA

    Institute of Scientific and Technical Information of China (English)

    JIAO Shuke; CHEN Xiaonong; HU Liping; YAN Baozhen

    1990-01-01

    The study on 13C-NMR spectra of aliphatic carbon region of emulsion-processed and solution-processed ( by lithium catalyst ) SBR was carried out. The assignments for more than thirty odd peaks observed experimentally were made by using " corresponding analysis " method, combined with the empirical parameters reported in literature. The peak intensities were calculated based on Bernoullian statistic assumption.

  10. Direct dynamic measurement of intracellular and extracellular lactate in small-volume cell suspensions with (13)C hyperpolarised NMR

    NARCIS (Netherlands)

    Breukels, V.; Jansen, K.F.J.; Heijster, F.H.A. van; Capozzi, A.; Bentum, P.J. van; Schalken, J.A.; Comment, A.; Scheenen, T.W.J.

    2015-01-01

    Hyperpolarised (HP) (13)C NMR allows enzymatic activity to be probed in real time in live biological systems. The use of in vitro models gives excellent control of the cellular environment, crucial in the understanding of enzyme kinetics. The increased conversion of pyruvate to lactate in cancer cel

  11. Solid-state 13C NMR and molecular modeling studies of acetyl aleuritolic acid obtained from Croton cajucara Benth

    Science.gov (United States)

    da Silva San Gil, Rosane Aguiar; Albuquerque, Magaly Girão; de Alencastro, Ricardo Bicca; da Cunha Pinto, Angelo; do Espírito Santo Gomes, Fabiano; de Castro Dantas, Tereza Neuma; Maciel, Maria Aparecida Medeiros

    2008-08-01

    Solid-state 13C nuclear magnetic resonance ( 13C NMR) with magic-angle spinning (MAS) and with cross-polarization and magic-angle spinning (CP/MAS) spectra, and differential scanning calorimetry (DSC) techniques were used to obtain structural data from a sample of acetyl aleuritolic acid (AAA) extracted from the stem bark of Croton cajucara Benth. (Euphorbiaceae) and recrystallized from acetone. Since solid-state 13C NMR results suggested the presence of more than one molecule in the unitary cell for the AAA, DSC analysis and molecular modeling calculations were used to access this possibility. The absence of phase transition peaks in the DSC spectra and the dimeric models of AAA simulated using the semi-empirical PM3 method are in agreement with that proposal.

  12. Espectroscopia de Ressonância Magnética Nuclear de 13C no estudo de rotas biossintéticas de produtos naturais 13C Nuclear Magnetic Resonance spectroscopy in the studies of biosythetic routes of natural products

    Directory of Open Access Journals (Sweden)

    Fernando César de Macedo Júnior

    2007-02-01

    Full Text Available During the last five decades, as a result of an interaction between natural product chemistry, synthetic organic chemistry, molecular biology and spectroscopy, scientists reached an extraordinary level of comprehension about the natural processes by which living organisms build up complex molecules. In this context, 13C nuclear magnetic resonance spectroscopy, allied with isotopic labeling, played a determinant role. Nowadays, the widespread use of modern NMR techniques allows an even more detailed picture of the biochemical steps by accurate manipulation of the atomic nuclei. This article focuses on the development of such techniques and their impact on biosynthetic studies.

  13. Enzymatic 13C Labeling and Multidimensional NMR Analysis of Miltiradiene Synthesized by Bifunctional Diterpene Cyclase in Selaginella moellendorffii*

    Science.gov (United States)

    Sugai, Yoshinori; Ueno, Yohei; Hayashi, Ken-ichiro; Oogami, Shingo; Toyomasu, Tomonobu; Matsumoto, Sadamu; Natsume, Masahiro; Nozaki, Hiroshi; Kawaide, Hiroshi

    2011-01-01

    Diterpenes show diverse chemical structures and various physiological roles. The diversity of diterpene is primarily established by diterpene cyclases that catalyze a cyclization reaction to form the carbon skeleton of cyclic diterpene. Diterpene cyclases are divided into two types, monofunctional and bifunctional cyclases. Bifunctional diterpene cyclases (BDTCs) are involved in hormone and defense compound biosyntheses in bryophytes and gymnosperms, respectively. The BDTCs catalyze the successive two-step type-B (protonation-initiated cyclization) and type-A (ionization-initiated cyclization) reactions of geranylgeranyl diphosphate (GGDP). We found that the genome of a lycophyte, Selaginella moellendorffii, contains six BDTC genes with the majority being uncharacterized. The cDNA from S. moellendorffii encoding a BDTC-like enzyme, miltiradiene synthase (SmMDS), was cloned. The recombinant SmMDS converted GGDP to a diterpene hydrocarbon product with a molecular mass of 272 Da. Mutation in the type-B active motif of SmMDS abolished the cyclase activity, whereas (+)-copalyl diphosphate, the reaction intermediate from the conversion of GGDP to the hydrocarbon product, rescued the cyclase activity of the mutant to form a diterpene hydrocarbon. Another mutant lacking type-A activity accumulated copalyl diphosphate as the reaction intermediate. When the diterpene hydrocarbon was enzymatically synthesized from [U-13C6]mevalonate, all carbons were labeled with 13C stable isotope (>99%). The fully 13C-labeled product was subjected to 13C-13C COSY NMR spectroscopic analyses. The direct carbon-carbon connectivities observed in the multidimensional NMR spectra demonstrated that the hydrocarbon product by SmMDS is miltiradiene, a putative biosynthetic precursor of tanshinone identified from the Chinese medicinal herb Salvia miltiorrhiza. Hence, SmMDS functions as a bifunctional miltiradiene synthase in S. moellendorffii. In this study, we demonstrate that one-dimensional and

  14. 13C NMR spectra of tectonic coals and the effects of stress on structural components

    Institute of Scientific and Technical Information of China (English)

    JU Yiwen; JIANG Bo; HOU Quanlin; WANG Guiliang; NI Shanqin

    2005-01-01

    High-resolution 13C Nuclear Magnetic Resonance (NMR) spectra of different kinds of tectonic coals were obtained using the NMR (CP/MAS+TOSS) method. On the basis of this, after simulation synthesis and division of spectra, the relative contents of carbon functional groups were calculated. Combined with results of Ro, max, XRD testing and element analysis, stress effects on the composition of macromolecular structures in tectonic coals were studied further. The results showed that Ro, max was not only the important index for describing coal rank, but was also effective for estimating the stress effect of tectonic coals. Under tectonic stress action, Ro, max was the most direct indicator of the coal structure and chemical components. Changes in the stacking Lc of the coal basic structure unit (BSU) and La/Lc parameters could distinguish the temperature and stress effects on metamorphic-deformed environments, and reflected the degree of structural deformation. Therefore, on the whole, Lc and La/Lc can be used to index of the degree of structural deformation of tectonic coals. In different metamorphic and deformed environments, different kinds of tectonic coals are formed under structural stress. The changes in characteristics of the macromolecular structure and chemical composition are such that as the increase in structural deformation becomes stronger, from the brittle deformation coal to ductile deformation coal, the ratio of width at the half height of the aromatic carbon and aliphatic carbon peaks (Hfa/Hfal ) was increased. As carbon aromaticity was raised further, carbon aliphaticity reduced obviously and different compositions of macromolecular structure appeared as a jump and wave pattern except for in wrinkle structure coal, which might result chiefly from stress effects on the macromolecular structure of different kinds of tectonic coals. The macromoecular changes of wrinkle structure coal are reflected mainly on physical structure. In the metamorphic and

  15. Origin of the conformational modulation of the 13C NMR chemical shift of methoxy groups in aromatic natural compounds.

    Science.gov (United States)

    Toušek, Jaromír; Straka, Michal; Sklenář, Vladimír; Marek, Radek

    2013-01-24

    The interpretation of nuclear magnetic resonance (NMR) parameters is essential to understanding experimental observations at the molecular and supramolecular levels and to designing new and more efficient molecular probes. In many aromatic natural compounds, unusual (13)C NMR chemical shifts have been reported for out-of-plane methoxy groups bonded to the aromatic ring (~62 ppm as compared to the typical value of ~56 ppm for an aromatic methoxy group). Here, we analyzed this phenomenon for a series of aromatic natural compounds using Density Functional Theory (DFT) calculations. First, we checked the methodology used to optimize the structure and calculate the NMR chemical shifts in aromatic compounds. The conformational effects of the methoxy group on the (13)C NMR chemical shift then were interpreted by the Natural Bond Orbital (NBO) and Natural Chemical Shift (NCS) approaches, and by excitation analysis of the chemical shifts, breaking down the total nuclear shielding tensor into the contributions from the different occupied orbitals and their magnetic interactions with virtual orbitals. We discovered that the atypical (13)C NMR chemical shifts observed are not directly related to a different conjugation of the lone pair of electrons of the methoxy oxygen with the aromatic ring, as has been suggested. Our analysis indicates that rotation of the methoxy group induces changes in the virtual molecular orbital space, which, in turn, correlate with the predominant part of the contribution of the paramagnetic deshielding connected with the magnetic interactions of the BD(CMet-H)→BD*(CMet-OMet) orbitals, resulting in the experimentally observed deshielding of the (13)C NMR resonance of the out-of-plane methoxy group.

  16. Biosynthetic studies of the glycopeptide teicoplanin by 1H and 13C NMR

    DEFF Research Database (Denmark)

    Heydorn, Arne; Petersen, Bent O.; Duus, Jens Øllgaard;

    2000-01-01

    The biosynthesis of the glycopeptide antibiotic teicoplanin was studied by growing a teicoplanin producing strain of Actinoplanes teichomyceticus (ATCC 31121) on glucose containing either 34.0% [1-13C]glucose or 9.7% [U- 13C]glucose. The fractional enrichment pattern of teicoplanin produced in th...

  17. Diazanaphthalenes: A 13C NMR investigation on the site of protonation and pKa values

    NARCIS (Netherlands)

    Weijer, van de Peter; Thijsse, Hans; Meer, van der Douwe

    1976-01-01

    The pH dependence of the 13C chemical shifts (δ) of the diazanaphthalenes has been recorded. From this dependence the pKa values have been determined using the Henderson-Hasselbach equation. The change in 13C chemical shifts under the influence of nitrogen protonation (Δδ) has been predicted using t

  18. Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of 13C-iodomethane

    Science.gov (United States)

    Park, Gregory H. J.; Martin, Rachel W.; Sakellariou, Dimitris; Pines, Alexander; Shahkhatuni, Aleksan G.; Shahkhatuni, Astghik A.; Panosyan, Henry A.

    2004-11-01

    NMR spectra of 13C-iodomethane oriented in three different liquid crystalline solvents have been collected and analyzed under spinning at various angles with respect to the static magnetic field. For each sample the ratio of homonuclear ( 1H- 1H) to heteronuclear ( 13C- 1H) dipolar couplings, which is a function of the geometry of the solute molecule, does not change significantly with the scaling of the dipolar couplings due to spinning at different angles. This result implies that the 'apparent bond angle deviations' (Δ θa), previously calculated from thermotropic liquid crystals, arise from a solvent effect and are not an artifact from scaling the anisotropic interactions.

  19. Toward dynamic isotopomer analysis in the rat brain in vivo: automatic quantitation of 13C NMR spectra using LCModel

    OpenAIRE

    Henry, Pierre-Gilles; Oz, Gülin; Provencher, Stephen; Gruetter, Rolf

    2003-01-01

    The LCModel method was adapted to analyze localized in vivo (13)C NMR spectra obtained from the rat brain in vivo at 9.4 T. Prior knowledge of chemical-shifts, J-coupling constants and J-evolution was included in the analysis. Up to 50 different isotopomer signals corresponding to 10 metabolites were quantified simultaneously in 400 microl volumes in the rat brain in vivo during infusion of [1,6-(13)C(2)]glucose. The analysis remained accurate even at low signal-to-noise ratio of the order of...

  20. 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

  1. The study of a monocotyledon abscission zone using microscopic, chemical, enzymatic and solid state 13C CP/MAS NMR analyses.

    Science.gov (United States)

    Henderson, J; Davies, H A; Heyes, S J; Osborne, D J

    2001-01-01

    We have investigated distinguishing features in cells of the abscission zone of a monocotyledon fruit, the oil palm Elaeis guineensis. The cell walls of the abscission zone and the subtending mesocarp and pedicel have been analysed by light and transmission electron microscopy, by chemical methods and by solid state 13C CP/MAS NMR spectroscopy. Results show that these abscission zone cells have specific characteristics which include high levels of unmethylated pectin in the walls and an inducible (x35) polygalacturonase enzyme expression. Together these findings help to explain the localised precision of cell separation events. PMID:11219806

  2. 1H and 13C NMR studies of palladium(2) and platinium(2) complexes with S-Methyl-L-Cysteine

    International Nuclear Information System (INIS)

    Our recent 1H NMR studies on Pd(2)-S-Methyl-L-Cysteine(SMC) complexes have shown that the use of a conformational analysis to establish the complexed species existing in solution may provide clearer results than considering the proton chemical shift only. However, the use of the vicinal coupling constant of ABC spectrum of αCH-βCH2 proton unit to estimate the rotational isomer fractions, may contain some ambiguity, especially on the proton assignment of the methylene group. For this reason 13C NMR method has been applied to study these systems. (author)

  3. Solid state 13C NMR and carbon isotope studies of the coupling of primary and secondary productivity in a Florida estuary

    International Nuclear Information System (INIS)

    The mechanisms by which primary producers fuel the growth of secondary consumers (e.g. fish and shell fish) in estuaries is poorly understood at this time. The authors have attempted to quantify the relative importance of detrital vs. planktonic food webs which support mariculture in the Ochlocknee River and Bay in Northwest Florida using stable carbon isotopes and solid state 13C NMR spectroscopy. Due to isotopic fractionation caused by different enzymatic pathways of carbon dioxide uptake, primary producers are imprinted with distinctive 13C/12C isotopic ratios. Stable isotopic ratios are imprints, or signatures, which are passed on to the next higher trophic level (you are what you eat). They have been combining isotopic tracing of food webs in estuaries with characterization of complex macromolecular particulates by cross polarization - magic angle spinning 13C NMR. In this talk they will demonstrate how the combination of these techniques can differentiate the relative importance of terrestrial input of organic matter vs. in situ estuarine production as a food source for estuarine consumers

  4. Fluorescence, CD, attenuated total reflectance (ATR) FTIR, and sup 13 C NMR characterization of the structure and dynamics of synthetic melittin and melittin analogues in lipid environments

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, A.J.; Prendergast, F.G. (Mayo Foundation, Rochester, MN (United States)); Kemple, M.D. (Indiana Univ.-Purdue Univ., Indianapolis (United States)); Brauner, J.W.; Mendelsohn, R. (Rutgers, The State Univ. of New Jersey, Newark (United States))

    1992-02-11

    The structure and dynamics of synthetic melittin (MLT) and MLT analogues bound to monomyristoylphosphatidylcholine micelles, dimyristoylphosphatidylcholine vesicles, and diacylphosphatidylcholine films have been investigated by fluorescence, CD, attenuated total reflectance (ATR) FTIR, and {sup 13}C NMR spectroscopy. All of these methods provide information about peptide secondary structure and/or about the environment of the single tryptophan side chain in these lipid environments. ATR-FTIR data provide additional information about the orientation of helical peptide segments with respect to the bilayer plane. Steady-state fluorescence anisotropy, fluorescence lifetime, and {sup 13}C NMR relaxation data are used in concert to provide quantitative information about the dynamics of a single {sup 13}C{alpha}-labeled glycine incorporated into each of the MLT peptides at position 12. The cumulative structural and dynamic data are consistent with a model wherein the N-terminal {alpha}-helical segment of these peptides is oriented perpendicular to the bilayer plane. Correlation times for the lysolipid-peptide complexes provide evidence for binding of a single peptide monomer per micelle. A model for the membranolytic action of MLT and MLT-like peptides is proposed.

  5. Unified and isomer-specific NMR metabolomics database for the accurate analysis of (13)C-(1)H HSQC spectra.

    Science.gov (United States)

    Bingol, Kerem; Li, Da-Wei; Bruschweiler-Li, Lei; Cabrera, Oscar A; Megraw, Timothy; Zhang, Fengli; Brüschweiler, Rafael

    2015-02-20

    A new metabolomics database and query algorithm for the analysis of (13)C-(1)H HSQC spectra is introduced, which unifies NMR spectroscopic information on 555 metabolites from both the Biological Magnetic Resonance Data Bank (BMRB) and Human Metabolome Database (HMDB). The new database, termed Complex Mixture Analysis by NMR (COLMAR) (13)C-(1)H HSQC database, can be queried via an interactive, easy to use web interface at http://spin.ccic.ohio-state.edu/index.php/hsqc/index . Our new HSQC database separately treats slowly exchanging isomers that belong to the same metabolite, which permits improved query in cases where lowly populated isomers are below the HSQC detection limit. The performance of our new database and query web server compares favorably with the one of existing web servers, especially for spectra of samples of high complexity, including metabolite mixtures from the model organisms Drosophila melanogaster and Escherichia coli. For such samples, our web server has on average a 37% higher accuracy (true positive rate) and a 82% lower false positive rate, which makes it a useful tool for the rapid and accurate identification of metabolites from (13)C-(1)H HSQC spectra at natural abundance. This information can be combined and validated with NMR data from 2D TOCSY-type spectra that provide connectivity information not present in HSQC spectra. PMID:25333826

  6. 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...

  7. Solid-state 13C NMR analysis of Lower Cretaceous Baganuur (Mongolia) lignite

    Science.gov (United States)

    Erdenetsogt, B.; Lee, I.; Lee, S.; Ko, Y.

    2009-12-01

    The transformation of plant matter into peat and coal has two steps, called the biochemical and geochemical stages of coalification. Biochemical coalification begins with the accumulation of dead vegetable matter and ends at the rank of subbituminous coal. The rank of Baganuur lignite ranges from lignite to subbituminous coal. It is transition between biochemical and physico-chemical coalification stages. The changes of chemical structure of coal during the transition between above mentioned two stages were studied by solid state CP/MAS 13C NMR. The most predominant alteration is the disappearance of the resonances from oxygenated aliphatic carbons (63 ppm), protonated aromatic carbons (114 ppm), oxygen-substituted aromatic carbons (144 ppm) and carbonyl carbons (195 ppm). In addition, the intensity of resonances from methoxyl carbons (56 ppm) and oxygenated aliphatic carbons (72 ppm) decreased. While the intensities of resonance from aliphatic (30 ppm), protonated aromatic (125 ppm) and carboxyl carbon (174 ppm) increased or remained almost constant. The relative percent of O-substituted aromatic carbons decreased by ~25% mainly due to the intensity loss of the peak at 144 ppm, indicating removal of O-containing functional groups substituted to aromatic carbons. It is consistent with the decreased relative percent (~75%) of the peak at 114 ppm from protonated aromatic carbons nearby oxygen-substituted aromatic carbons. In addition, the resonance from 125 ppm was shifted to 128 ppm and its relative area increased by ~20%, indicating replacement of O-substituent of aromatic rings by hydrogen or carbon. Protonated aromatic carbons at least two bond away from an oxygen-substituted aromatic carbons give a resonance at 125 ppm and carbon-substituted aromatic carbons give a resonance at 130-132 ppm. With the increase relative percent of C-substituted aromatic carbons, their resonance were overlapped with protonated aromatic carbons and shifted to higher ppm. A decreasing

  8. Soil organic degradation: bridging the gap between Rock-Eval pyrolysis and chemical characterization (CPMAS 13C NMR)

    Science.gov (United States)

    Albrecht, Remy; Sebag, David; Verrecchia, Eric

    2013-04-01

    Being a source of mineral nutrients, organic matter contributes to soil chemical fertility and acts on soil physical fertility through its role in soil structure. Soil organic matter (SOM) is a key component of soils. Despite the paramount importance of SOM, information on its chemistry and behaviour in soils is incomplete. Numerous methods are used to characterize and monitor OM dynamics in soils using different approaches (Kogel-Knabner, 2000). Two of the main approaches are evaluated and compared in this study. Rock-Eval pyrolysis (RE pyrolysis) provides a description of a SOM's general evolution using its thermal resistance. The second tool (13C CPMAS NMR) aims to give precise and accurate chemical information on OM characterization. The RE pyrolysis technique was designed for petroleum exploration (Lafargue et al., 1998) and because of its simplicity, it has been applied to a variety of other materials such as soils or Recent sediments (Disnar et al., 2000; Sebag, 2006). Recently, RE pyrolysis became a conventional tool to study OM dynamics in soils. In RE pyrolysis, a peak deconvolution is applied to the pyrolysis signal in order to get four main components related to major classes of organic constituents. These components differ in origin and resistance to pyrolysis: labile biological constituents (F1), resistant biological constituents (F2), immature non-biotic constituents (F3) and a mature refractory fraction (F4) (Sebag, 2006; Coppard, 2006). Main advantages of the technique are its repeatability, and rapidity to provide an overview of OM properties and stocks. However, do the four major classes used in the literature reflect a pertinent chemical counterpart? To answer this question, we used 13C Nuclear Magnetic Resonance Spectroscopy in the solid state (13C CPMAS NMR) to collect direct information on structural and conformational characteristics of OM. NMR resonances were assigned to chemical structures according to five dominant forms: alkyl C, O

  9. 13C NMR DETERMINATION OF EIGHT BENZO[h]QUINOLINES%8种苯并[h]喹啉的13C NMR归属

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    报道了8种新的苯并[h]喹啉的13C NMR谱.应用13C NMR等谱确定了这8种新化合物的分子结构,并对全部谱峰进行了归属,初步探讨了分子结构对13C NMR化学位移的影响.

  10. Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time 13C CP-MAS solid-state NMR characterization

    Directory of Open Access Journals (Sweden)

    Isabelle Mallard

    2015-12-01

    Full Text Available The polymerization of partially methylated β-cyclodextrin (CRYSMEB with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3 of imprinted polymers were obtained and characterized by solid-state 13C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: TCH (the CP time constant and T1ρ (the proton spin-lattice relaxation time in the rotating frame. The results and the analysis presented in the paper pointed out that TCH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of TCH and T1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices.

  11. Alkaline Hydrolysis/Polymerization of 2,4,6-Trinitrotoluene: Characterization of Products by 13C and 15N NMR

    Science.gov (United States)

    Thorn, K.A.; Thorne, P.G.; Cox, L.G.

    2004-01-01

    Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp 3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp 2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to

  12. Polydisperse methyl β-cyclodextrin-epichlorohydrin polymers: variable contact time (13)C CP-MAS solid-state NMR characterization.

    Science.gov (United States)

    Mallard, Isabelle; Baudelet, Davy; Castiglione, Franca; Ferro, Monica; Panzeri, Walter; Ragg, Enzio; Mele, Andrea

    2015-01-01

    The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state (13)C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices. PMID:26877800

  13. Local structure and molecular motions in imidazolium hydrogen malonate crystal as studied by 2H and 13C NMR

    International Nuclear Information System (INIS)

    The local structure and molecular motion of the imidazolium hydrogen malonate crystal were investigated using solid-state 2H and 13C NMR. The imidazolium ion undergoes isotropic rotation, which is correlated with a defect in the crystal, as observed by 2H NMR broadline spectra above 263 K. A 180∘ flip of the imidazolium ion in the regular site was observed from 2H NMR quadrupole Carr-Purcell-Meiboom-Gill (QCPMG) spectra. The Grotthuss mechanism was accompanied by a 180∘ flip of the imidazolium ion in regular sites. Moreover, the proton transfer associated with the imidazolium ion of the defective crystal is important for proton conductivity of the imidazolium hydrogen malonate crystal

  14. DMS AND 13C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVA c/PBA

    Institute of Scientific and Technical Information of China (English)

    YAN Xin; XU Xiaolong; ZHANG Baozhen; YAO Shuren; QIAN Baogong

    1993-01-01

    The compatibility and dynamics of latex bidirectional interpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the 13C linewidths of PBA and temperature is also discussed.

  15. 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.

  16. (13)C, (15)N CPMAS NMR and GIAO DFT calculations of stereoisomeric oxindole alkaloids from Cat's Claw (Uncaria tomentosa).

    Science.gov (United States)

    Paradowska, Katarzyna; Wolniak, Michał; Pisklak, Maciej; Gliński, Jan A; Davey, Matthew H; Wawer, Iwona

    2008-11-01

    Oxindole alkaloids, isolated from the bark of Uncaria tomentosa [Willd. ex Schult.] Rubiaceae, are considered to be responsible for the biological activity of this herb. Five pentacyclic and two tetracyclic alkaloids were studied by solid-state NMR and theoretical GIAO DFT methods. The (13)C and (15)N CPMAS NMR spectra were recorded for mitraphylline, isomitraphylline, pteropodine (uncarine C), isopteropodine (uncarine E), speciophylline (uncarine D), rhynchophylline and isorhynchophylline. Theoretical GIAO DFT calculations of shielding constants provide arguments for identification of asymmetric centers and proper assignment of NMR spectra. These alkaloids are 7R/7S and 20R/20S stereoisomeric pairs. Based on the (13)C CP MAS chemical shifts the 7S alkaloids (delta C3 70-71ppm) can be easily and conveniently distinguished from 7R (deltaC3 74.5-74.9ppm), also 20R (deltaC20 41.3-41.7ppm) from the 20S (deltaC20 36.3-38.3ppm). The epiallo-type isomer (3R, 20S) of speciophylline is characterized by a larger (15)N MAS chemical shift of N4 (64.6ppm) than the allo-type (3S, 20S) of isopteropodine (deltaN4 53.3ppm). (15)N MAS chemical shifts of N1-H in pentacyclic alkaloids are within 131.9-140.4ppm.

  17. Assigning large proteins in the solid state: a MAS NMR resonance assignment strategy using selectively and extensively {sup 13}C-labelled proteins

    Energy Technology Data Exchange (ETDEWEB)

    Higman, Victoria A. [Leibniz-Institut fuer Molekulare Pharmakologie (Germany); Flinders, Jeremy [Genentech, Inc., Structural Biology Department (United States); Hiller, Matthias; Jehle, Stefan; Markovic, Stefan; Fiedler, Sebastian; Rossum, Barth-Jan van; Oschkinat, Hartmut [Leibniz-Institut fuer Molekulare Pharmakologie (Germany)], E-mail: oschkinat@fmp-berlin.de

    2009-08-15

    In recent years, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) has been growing into an important technique to study the structure of membrane proteins, amyloid fibrils and other protein preparations which do not form crystals or are insoluble. Currently, a key bottleneck is the assignment process due to the absence of the resolving power of proton chemical shifts. Particularly for large proteins (approximately >150 residues) it is difficult to obtain a full set of resonance assignments. In order to address this problem, we present an assignment method based upon samples prepared using [1,3-{sup 13}C]- and [2-{sup 13}C]-glycerol as the sole carbon source in the bacterial growth medium (so-called selectively and extensively labelled protein). Such samples give rise to higher quality spectra than uniformly [{sup 13}C]-labelled protein samples, and have previously been used to obtain long-range restraints for use in structure calculations. Our method exploits the characteristic cross-peak patterns observed for the different amino acid types in {sup 13}C-{sup 13}C correlation and 3D NCACX and NCOCX spectra. An in-depth analysis of the patterns and how they can be used to aid assignment is presented, using spectra of the chicken {alpha}-spectrin SH3 domain (62 residues), {alpha}B-crystallin (175 residues) and outer membrane protein G (OmpG, 281 residues) as examples. Using this procedure, over 90% of the C{alpha}, C{beta}, C' and N resonances in the core domain of {alpha}B-crystallin and around 73% in the flanking domains could be assigned (excluding 24 residues at the extreme termini of the protein)

  18. Unraveling the complexity of protein backbone dynamics with combined (13)C and (15)N solid-state NMR relaxation measurements.

    Science.gov (United States)

    Lamley, Jonathan M; Lougher, Matthew J; Sass, Hans Juergen; Rogowski, Marco; Grzesiek, Stephan; Lewandowski, Józef R

    2015-09-14

    Typically, protein dynamics involve a complex hierarchy of motions occurring on different time scales between conformations separated by a range of different energy barriers. NMR relaxation can in principle provide a site-specific picture of both the time scales and amplitudes of these motions, but independent relaxation rates sensitive to fluctuations in different time scale ranges are required to obtain a faithful representation of the underlying dynamic complexity. This is especially pertinent for relaxation measurements in the solid state, which report on dynamics in a broader window of time scales by more than 3 orders of magnitudes compared to solution NMR relaxation. To aid in unraveling the intricacies of biomolecular dynamics we introduce (13)C spin-lattice relaxation in the rotating frame (R1ρ) as a probe of backbone nanosecond-microsecond motions in proteins in the solid state. We present measurements of (13)C'R1ρ rates in fully protonated crystalline protein GB1 at 600 and 850 MHz (1)H Larmor frequencies and compare them to (13)C'R1, (15)N R1 and R1ρ measured under the same conditions. The addition of carbon relaxation data to the model free analysis of nitrogen relaxation data leads to greatly improved characterization of time scales of protein backbone motions, minimizing the occurrence of fitting artifacts that may be present when (15)N data is used alone. We also discuss how internal motions characterized by different time scales contribute to (15)N and (13)C relaxation rates in the solid state and solution state, leading to fundamental differences between them, as well as phenomena such as underestimation of picosecond-range motions in the solid state and nanosecond-range motions in solution.

  19. Sup(13)C NMR studies of glucose disposal in normal and non-insulin-dependent diabetic humans

    International Nuclear Information System (INIS)

    To examine the extent to which the defect in insulin action in subjects with non-insulin-dependent diabetes mellitus (NIDDM) can be accounted for by impairment of muscle glycogen synthesis, we performed combined hyperglycemic-hyperinsulinemic clamp studies with [13C]glucose in five subjects with NIDDM and in six age- and weight-matched healthy subjects. The rate of incorporation of intravenously infused [1-13C]glucose into muscle glycogen was measured directly in the gastrocnemius muscle by means of a nuclear magnetic resonance (NMR) spectrometer with a 15.5 min time resolution and a 13C surface coil. The steady-state plasma concentrations of insulin and glucose were similar in both study groups. The mean (±SE) rate of glycogen synthesis, as determined by 13C NMR, was 78±28 and 183±39 μmol-glucosyl units (kg muscle tissue (wet mass))-1 min-1 in the diabetic and normal subjects, respectively. The mean glucose uptake was markedly reduced in the diabetic as compared with the normal subjects. The mean rate of non-oxidative glucose metabolism was 22±4 μmol kg-1 min-1 in the diabetic subjects and 42±4 μmol kg-1 min-1 in the normal subjects. When these rates are extrapolated to apply to the whole body, the synthesis of muscle glycogen would account for most of the total-body glucose uptake and all of the non-oxidative glucose metabolism in both normal and diabetic subjects. We conclude that muscle glycogen synthesis is the principal pathway of glucose disposal in both normal and diabetic subjects and that defects in muscle glycogen synthesis have a dominant role in the insulin resistance that occurs in persons with NIDDM. (author)

  20. STUDIES ON RADIATION INDUCED CROSSLINKING OF CIS 1,4—POLYBUTADIENE BY 13C NMR

    Institute of Scientific and Technical Information of China (English)

    赵新; 杜有如; 等

    1994-01-01

    13C NMR spin-lattice relaxation times(T1),line widths,nuclear Overhauser effects(NOE) at room temperature have been measured for radiated cis 1,4-polybutadiene.With the increase of radiation dose T1 is almost invariant,but line width of the methylene(-CH2-) carbon increases remarkably,and its NOE factor decreases sharply,This implies that the long-range segmental motion is hindered,and satureated tertiary carbon(CH-)is formed during crossliking of cis 1,4-polybutadiene.

  1. Applications of artificial intelligence techniques to organic chemistry. Study on 13C NMR of steroids using computer

    International Nuclear Information System (INIS)

    This work describes the utilization of two groups of programs in searching for characteristic signals of NMR 13C steroidal compounds. The first group of programs used data bases with the spectral data and a methodology that enables the choice and the search of substructures. The chemical shifts and multiplicities for each specific substructure are used as rules to identify different types and subtypes of steroidal compounds. The second one was built to apply the rules formulated by the first group of programs and to foresee any skeletal based on a spectral analysis. (author)

  2. Studies on metabolic regulation using NMR spectroscopy.

    Science.gov (United States)

    Bachelard, H; Badar-Goffer, R; Ben-Yoseph, O; Morris, P; Thatcher, N

    1993-01-01

    The effects of hypoxia and hypoglycaemia on cerebral metabolism and calcium have been studied using multinuclear magnetic resonance spectroscopy. 13C MRS showed that severe hypoxia did not cause any further increase in metabolic flux into lactate seen in mild hypoxia, but there was a further increase in 13C labelling of alanine and glycerol 3-phosphate. These results are discussed in terms of the ability of lactate dehydrogenase to maintain normal levels of NADH in mild hypoxia, but not in severe hypoxia. We conclude that glycerol 3-phosphate and alanine may provide novel means of monitoring severe hypoxia whereas lactate is a reliable indicator only of mild hypoxia. 19F- and 31P NMR spectroscopy showed that neither hypoxia nor hypoglycaemia alone caused any significant change in [Ca2+]i. Combined sequential insults (hypoxia, followed by hypoxia plus hypoglycaemia), or vice versa, produced a 100% increase in [Ca2+]i, whereas immediate exposure to the combined insult (hypoxia plus hypoglycaemia) resulted in a large 5-fold increase in [Ca2+]i, with severe irreversible effects on the energy state. These results are discussed in terms of metabolic adaptation to the single type of insult, which renders the tissue less vulnerable to the combined insult. The effects of this combined insult are far more severe than those caused by glutamate or NMDA, which throws doubt on the current excitoxic hypothesis of cell damage.

  3. Analysis of the mechanical properties and characterization by solid state 13C NMR of recycled EVA copolymer/silica composites

    Directory of Open Access Journals (Sweden)

    Giovanni Chaves Stael

    2005-09-01

    Full Text Available The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM, and the 13C Nuclear Magnetic Resonance (NMR showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group.

  4. Analysis of the mechanical properties and characterization by solid state 13 C NMR of recycled EVA copolymer/silica composites

    International Nuclear Information System (INIS)

    The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate) - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM), and the 13 C Nuclear Magnetic Resonance (NMR) showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group. (author)

  5. Structure of UC{sub 2} and U{sub 2}C{sub 3}:XRD, {sup 13}C NMR and EXAFS study

    Energy Technology Data Exchange (ETDEWEB)

    Carvajal Nuñez, U. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Eloirdi, R., E-mail: rachel.eloirdi@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); Prieur, D.; Martel, L. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany); López Honorato, E. [Centro de Investigatión y de Estudios Avanzados del IPN (CINVESTAV), Unidad Saltillo, Av. Industria Metalúrgica 1062, Ramos Arizpe, Coahuila 25900 (Mexico); Farnan, I. [University of Cambridge, Cambridge CB2 1TN (United Kingdom); Vitova, T. [Institut für Nukleare Entsorgung (INE), P.O. Box 3640, D- 76021 Karlsruhe (Germany); Somers, J. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe (Germany)

    2014-03-15

    Highlights: • A structural investigation of UC{sub 2} and U{sub 2}C{sub 3} phases was made with XRD, NMR and EXAFS. • Heat treatment of a pulverised UC{sub 2} ingot, repressed into a pellet yields a U{sub 2}C{sub 3} phase coexisting with UC{sub 2−z}. • Heat treatment of UC{sub 2} as cast ingots results in a partial decomposition to UC. • EXAFS data confirmed the CaC{sub 2} and Pu{sub 2}C{sub 3} type structure for UC{sub 2} and U{sub 2}C{sub 3} respectively. • {sup 13}C MAS NMR identified a contribution of a well and less ordered phases in UC{sub 2}. -- Abstract: In this study, uranium dicarbide (UC{sub 2}) has been prepared by arc melting and heat treated under vacuum to form uranium sequicarbide (U{sub 2}C{sub 3}) in the presence of a second phase UC{sub 2−z}. Both samples, as cast and heat treated, have been characterised by chemical analyses, X-ray diffraction (XRD), {sup 13}C magic angle spinning nuclear magnetic resonance (MAS-NMR) and by extended X-ray absorption fine structure (EXAFS). The composition, the purity, the various environments of both U and C atoms as well as the bonds length with the coordination number have been determined. By combining a long-range order method (XRD) and short-range order spectroscopy techniques (EXAFS and NMR), a unique view on the microstructure of UC{sub 2}, before and after heat treatment, and of U{sub 2}C{sub 3} phase has been achieved.

  6. XRD, FTIR and 13C CP/ MAS NMR Studies of Composite Comprising Poly(vinyl acetate)- silylated Si-MCM-41

    International Nuclear Information System (INIS)

    A composite structure based on silylated MCM-41 and Poly(vinyl acetate) (PVAc) was synthesized via solution intercalation. Poly(vinyl acetate)-silylated Si- MCM-41 composite were characterized by XRD, FTIR spectroscopy and 13C CP/ MAS NMR in order to determine the compatibility between PVAc and the silicate host. XRD study reveals that the framework of silylated Si-MCM-41 was not altered upon incorporation of PVAc. FTIR study showed that characteristic peak assigned to carbonyl group in PVAc was observed around 1741.6 cm-1 for all the composites indicating the presence of PVAc in the silylated Si-MCM-41. 13C CP/ MAS NMR showed the increase of line width of the peak assigned to C=O carbonyl group indicating the increase in randomness of polymer chains in confined space. The shifting of the C=O carbonyl groups is a sign of the change in chemical environment of the carbonyl owing to the interaction of PVAc with the silica matrix of silylated Si-MCM-41. (author)

  7. /sup 13/C NMR of diterpenes with isopimarane structure. Part 2: effects involving the double bond. delta. sup(8(9))

    Energy Technology Data Exchange (ETDEWEB)

    Cunha Pinto, A. da; Lima Pereira, A. de (Rio de Janeiro Univ. (Brazil). Nucleo de Pesquisas de Produtos Naturais)

    1984-01-01

    Several effects of the ..delta.. sup(8(9)) double bond on the /sup 13/C NMR data of isopimarane diterpenoids are discussed, including chemical shifts and acetylation of the C-7 hydroxyl radical on the above mentioned double bond.

  8. Introducing NMR to a General Chemistry Audience: A Structural-Based Instrumental Laboratory Relating Lewis Structures, Molecular Models, and [superscript 13]C NMR Data

    Science.gov (United States)

    Pulliam, Curtis R.; Pfeiffer, William F.; Thomas, Alyssa C.

    2015-01-01

    This paper describes a first-year general chemistry laboratory that uses NMR spectroscopy and model building to emphasize molecular shape and structure. It is appropriate for either a traditional or an atoms-first curriculum. Students learn the basis of structure and the use of NMR data through a cooperative learning hands-on laboratory…

  9. Advanced CPMAS-13C NMR techniques for molecular characterization of size-separated fractions from a soil humic acid.

    Science.gov (United States)

    Conte, Pellegrino; Spaccini, Riccardo; Piccolo, Alessandro

    2006-09-01

    A humic acid extracted from a volcanic soil was subjected to preparative high-performance size-exclusion chromatography (HPSEC) to reduce its molecular complexity and eleven different size fractions were obtained. Cross-polarization magic-angle spinning 13C NMR (CPMAS 13C NMR) analysis performed with variable contact-time (VCT) pulse sequences showed that the largest molecular-size fractions contained aromatic, alkyl, and carbohydrate-like components. The carbohydrate-like content and the alkyl chain length seemed to decrease with decreasing molecular size. Progressive reduction of aromatic carbon atoms was also observed with decreasing molecular size of the separated fractions. Mathematical treatment of the results from VCT experiments enabled cross polarization (T (CH)) and proton spin-lattice relaxation (T(1rho)(H)) times to be related to structural differences among the size fractions. The conformational distribution indicated that the eleven size fractions could be allocated to two main groups. The first group, with larger nominal molecular sizes, was characterized by molecular domains with slower local molecular motion. The second group of size fractions, with smaller nominal molecular sizes, was characterized by a larger number of molecular domains with faster local molecular motion. The T (CH) and (T(1rho)(H)) values suggested that either condensed or strongly associated aromatic systems were predominant in the size fractions with the largest apparent molecular dimensions. PMID:16896626

  10. The retrogradation properties of glutinous rice and buckwheat starches as observed with FT-IR, 13C NMR and DSC.

    Science.gov (United States)

    Lian, Xijun; Wang, Changjun; Zhang, Kunsheng; Li, Lin

    2014-03-01

    The experiment was conducted to study the retrogradation properties of glutinous rice and buckwheat starch with wavelengths of maximum absorbance, FT-IR, (13)C NMR, and DSC. The results show that the starches in retrograded glutinous rice starch and glutinous rice amylopectin could not form double helix. The IR results show that protein inhabits in glutinous rice and maize starches in a different way and appearance of C-H symmetric stretching vibration at 2852 cm(-1) in starch might be appearance of protein. Retrogradation untied the protein in glutinous amylopectin. Enthalpies of sweet potato and maize granules are higher than those of their retrograded starches. The (13)C NMR results show that retrogradation of those two starches leads to presence of β-anomers and retrogradation might decompose lipids in glutinous rice amylopectin into small molecules. Glutinous rice starch was more inclined to retrogradation than buckwheat starch. The DSC results show that the second peak temperatures for retrograded glutinous rice and buckwheat starches should be assigned to protein. The SEM results show that an obvious layer structure exists in retrograded glutinous rice amylopectin.

  11. Recognition of Membrane Sterols by Polyene Antifungals Amphotericin B and Natamycin, A (13)C MAS NMR Study.

    Science.gov (United States)

    Ciesielski, Filip; Griffin, David C; Loraine, Jessica; Rittig, Michael; Delves-Broughton, Joss; Bonev, Boyan B

    2016-01-01

    The molecular action of polyene macrolides with antifungal activity, amphotericin B and natamycin, involves recognition of sterols in membranes. Physicochemical and functional studies have contributed details to understanding the interactions between amphotericin B and ergosterol and, to a lesser extent, with cholesterol. Fewer molecular details are available on interactions between natamycin with sterols. We use solid state (13)C MAS NMR to characterize the impact of amphotericin B and natamycin on mixed lipid membranes of DOPC/cholesterol or DOPC/ergosterol. In cholesterol-containing membranes, amphotericin B addition resulted in marked increase in both DOPC and cholesterol (13)C MAS NMR linewidth, reflecting membrane insertion and cooperative perturbation of the bilayer. By contrast, natamycin affects little either DOPC or cholesterol linewidth but attenuates cholesterol resonance intensity preferentially for sterol core with lesser impact on the chain. Ergosterol resonances, attenuated by amphotericin B, reveal specific interactions in the sterol core and chain base. Natamycin addition selectively augmented ergosterol resonances from sterol core ring one and, at the same time, from the end of the chain. This puts forward an interaction model similar to the head-to-tail model for amphotericin B/ergosterol pairing but with docking on opposite sterol faces. Low toxicity of natamycin is attributed to selective, non-cooperative sterol engagement compared to cooperative membrane perturbation by amphotericin B. PMID:27379235

  12. Dynamic 13C NMR analysis of pyruvate and lactate oxidation in the in vivo canine myocardium: evidence of reduced utilization with increased work.

    Science.gov (United States)

    Rath, D P; Zhu, H; Tong, X; Jiang, Z; Hamlin, R L; Robitaille, P M

    1997-12-01

    In this work, substrate selection was monitored in the left ventricle of the canine myocardium by following pyruvate and lactate oxidation under in vivo conditions at basal and elevated workloads. These studies were conducted in the open chest model using dynamic 13C NMR techniques in the presence and absence of dichloroacetic acid (DCA), a well-known activator of pyruvate dehydrogenase (PDH). Following the infusion of (3-(13)C) pyruvate or (3-(13)C) lactate into the left anterior descending artery, highly variable 13C enrichments of glutamate, alanine, aspartate, and citrate were noted under low (RPP 25,500 mmHg/min) rate pressure products (RPP). At low workloads, the myocardium typically oxidized the infused (3-(13)C) pyruvate or (3-(13)C) lactate and incorporated the labeled carbon into the glutamate pool as expected. However, in a few notable instances (n = 3), 13C-enriched pyruvate and lactate were unable to label the glutamate pool under in vivo conditions even at the lowest RPPs, indicating a lack of selection for these substrates by the tricarboxylic acid (TCA) cycle. Nonetheless, the levels of glutamate C4 enrichment observed at low workloads could usually be enhanced by infusion of DCA. Importantly, 13C NMR extract analysis revealed that (3-(13)C) pyruvate or (3-(13)C) lactate labeling of the glutamate pool was reduced (< 20%) at high workloads in spite of increased DCA concentrations. PMID:9402190

  13. Substituent effects in the 13C NMR chemical shifts of alpha-mono-substituted acetonitriles.

    Science.gov (United States)

    Reis, Adriana K C A; Rittner, Roberto

    2007-03-01

    13C chemical shifts empirical calculations, through a very simple additivity relationship, for the alpha-methylene carbon of some alpha-mono-substituted acetonitriles, Y-CH(2)-CN (Y=H, F, Cl, Br, I, OMe, OEt, SMe, SEt, NMe(2), NEt(2), Me and Et), lead to similar, or even better, results in comparison to the reported values obtained through Quantum Mechanics methods. The observed deviations, for some substituents, are very similar for both approaches. This divergence between experimental and calculated, either empirically or theoretically, values are smaller than for the corresponding acetones, amides, acetic acids and methyl esters, which had been named non-additivity effects (or intramolecular interaction chemical shifts, ICS) and attributed to some orbital interactions. Here, these orbital interactions do not seem to be the main reason for the non-additivity effects in the empirical calculations, which must be due solely to the magnetic anisotropy of the heavy atom present in the substituent. These deviations, which were also observed in the theoretical calculations, were attributed in that case to the non-inclusion of relativistic effects and spin-orbit coupling in the Hamiltonian. Some divergence is also observed for the cyano carbon chemical shifts, probably due to the same reasons.

  14. Synergistic effect of the simultaneous chemometric analysis of {sup 1}H NMR spectroscopic and stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data: Application to wine analysis

    Energy Technology Data Exchange (ETDEWEB)

    Monakhova, Yulia B., E-mail: yul-monakhova@mail.ru [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Department of Chemistry, Saratov State University, Astrakhanskaya Street 83, Saratov 410012 (Russian Federation); Godelmann, Rolf [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Hermann, Armin [Landesuntersuchungsamt -Institut für Lebensmittelchemie und Arzneimittelprüfung, Emy-Roeder-Straße 1, Mainz 55129 (Germany); Kuballa, Thomas [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Cannet, Claire; Schäfer, Hartmut; Spraul, Manfred [Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Rutledge, Douglas N. [AgroParisTech, UMR 1145, Ingénierie Procédés Aliments, 16 rue Claude Bernard, Paris F-75005 (France)

    2014-06-23

    Highlights: • {sup 1}H NMR profilings of 718 wines were fused with stable isotope analysis data (SNIF-NMR, {sup 18}O, {sup 13}C). • The best improvement was obtained for prediction of the geographical origin of wine. • Certain enhancement was also obtained for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data). • Independent component analysis was used as an alternative chemometric tool for classification. - Abstract: It is known that {sup 1}H NMR spectroscopy represents a good tool for predicting the grape variety, the geographical origin, and the year of vintage of wine. In the present study we have shown that classification models can be improved when {sup 1}H NMR profiles are fused with stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data. Variable selection based on clustering of latent variables was performed on {sup 1}H NMR data. Afterwards, the combined data of 718 wine samples from Germany were analyzed using linear discriminant analysis (LDA), partial least squares-discriminant analysis (PLS-DA), factorial discriminant analysis (FDA) and independent components analysis (ICA). Moreover, several specialized multiblock methods (common components and specific weights analysis (ComDim), consensus PCA and consensus PLS-DA) were applied to the data. The best improvement in comparison with {sup 1}H NMR data was obtained for prediction of the geographical origin (up to 100% for the fused data, whereas stable isotope data resulted only in 60–70% correct prediction and {sup 1}H NMR data alone in 82–89% respectively). Certain enhancement was obtained also for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data), whereas in case of grape varieties improved models were not obtained. The combination of {sup 1}H NMR data with stable isotope data improves efficiency of classification models for geographical origin and vintage of wine and can be potentially used for other food products as well.

  15. Plant Resources, (13)C-NMR Spectral Characteristic and Pharmacological Activities of Dammarane-Type Triterpenoids.

    Science.gov (United States)

    Ruan, Jingya; Zheng, Chang; Qu, Lu; Liu, Yanxia; Han, Lifeng; Yu, Haiyang; Zhang, Yi; Wang, Tao

    2016-01-01

    Dammarane-type triterpenoids (DTT) widely distribute in various medicinal plants. They have generated a great amount of interest in the field of new drug research and development. Generally, DTT are the main bioactive ingredients abundant in Araliaceae plants, such as Panax ginseng, P. japonicas, P. notoginseng, and P. quinquefolium. Aside from Araliaceae, DTT also distribute in other families, including Betulaceae, Cucurbitaceae, Meliaceae, Rhamnaceae, and Scrophulariaceae. Until now, about 136 species belonging to 46 families have been reported to contain DTT. In this article, the genus classifications of plant sources of the botanicals that contain DTT are reviewed, with particular focus on the NMR spectral features and pharmacological activities based on literature reports, which may be benefit for the development of new drugs or food additives. PMID:27529202

  16. Molecular composition of recycled organic wastes, as determined by solid-state {sup 13}C NMR and elemental analyses

    Energy Technology Data Exchange (ETDEWEB)

    Eldridge, S.M., E-mail: simon.eldridge@dpi.nsw.gov.au [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); NSW Department of Primary Industries, Bruxner Highway, Wollongbar, NSW 2477 (Australia); Chen, C.R. [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); Xu, Z.H. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Nelson, P.N. [School of Earth and Environmental Sciences, James Cook University, Cairns, QLD 4870 (Australia); Boyd, S.E. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Meszaros, I. [Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia); Chan, K.Y. [Graduate School of Environment, Macquarie University, North Ryde, NSW 2109 (Australia); Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia)

    2013-11-15

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state {sup 13}C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

  17. Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses

    International Nuclear Information System (INIS)

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state 13C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes

  18. Applications of high-resolution solid-state NMR spectroscopy in food science.

    Science.gov (United States)

    Bertocchi, Fabio; Paci, Maurizio

    2008-10-22

    The principal applications of high-resolution solid-state NMR spectroscopy, in the field of food science, are reviewed, after a short general introduction, mainly focusing on the potential of these investigations, which are, today, routine tools for resolving technological problems. Selected examples of the applications in the field of food science of high-resolution solid-state NMR spectroscopy both in (13)C and in (1)H NMR particularly illustrative of the results obtainable are reported in some detail.

  19. Synthesis, GC-EIMS, ~1H NMR, ~(13)C NMR, Mechanistic and Thermal Studies of o-Xylylene-α,α'-bis(triphenylphosphinebromide)

    Institute of Scientific and Technical Information of China (English)

    Muddasir Hanif; LU Ping; XU Hai; TIAN Zhi-cheng; YANG Bing; WANG Zhi-ming; TIAN Lei-lei; XU Yuan-ze; XIE Zeng-qi; MA Yu-guang

    2009-01-01

    Organophosphorous compounds containing phosphorus as an integral part have been widely used in industry, organic synthesis and optoelectronics. o-Xylylene-α,α'-bis(triphenylphosphinebromide)(OXBTPPB) is a facile reagent to convert o-quinones(e.g., 9,10-phenanthrenequinone) into polycyclic aromatic hydrocarbons(PAHs). Herein lies an improved synthetic route to OXBTPPB. The resultant was carefully characterized with GC-EIMS, ~1H NMR, ~(13)C NMR, spectroscopic techniques. The EIMS shows characteristic peaks at m/z=262.4, 183.3, 108.2, 77.1 attributed to the [C_(18)H_(15)P]~+, [C_(18)H_8P]~+, [C_6H_5P]~+, [C_6H_5]~+ ions, respectively. The 1H and ~(13)C NMR spectrum shows well resolved peaks and all the hydrogens and carbons were well-assigned via a combined study of ~1H-~1H COSY, HMBC, and HMQC experiments. The mechanism for the formation of OXBTPPB was proposed based on literature and obtained experimental data. Meanwhile, the thermal stability of OXBTPPB was evaluated with TGA analysis, and an onset decomposition temperature(T_d) was recorded at 323.6℃.

  20. 1H, 13C and 31P-NMR spectroscopic study of glucose metabolism of muscle larva Trichinella spiralis (U.S.A. strain), and the effects of the end-products on the host (mouse)

    International Nuclear Information System (INIS)

    1H- and 13C-nuclear magnetic resonance (NMR) spectroscopy was used to identify and quantitate metabolites excreted by muscle larva Trichinella spiralis maintained aerobically in the presence of D- (13C6) glucose and (1, 1'-13C2) succinate. End-products of glucose metabolism studied by 1H-NMR were lactate, acetate, succinate, proionate, n-valerate and alanine, at the molar ratio of 1:2:1:0.6:0.5:0.6. 13C-NMR measurement proved that all the products originated from the glucose in the medium via the phosphoenolpyruvate carboxykinase-succinate pathway and the tricarboxylic acid cycle. In vivo 31P-NMR spectra were also taken by the surface coil method from the leg muscle of mice which had been infected with T. spiralis. Intracelluar pH and relative amount of ATP in the leg muscle of the infected mice were found to decrease significantly as compared with that of control mice. (author)

  1. Synthesis of biodiesel from rocket seed oil and its characterization by FT-IR, NMR (/sup 1/H and /sup 13/C) and GC-MS

    International Nuclear Information System (INIS)

    The limited resources of fossil fuel, increasing prices of crude oils and environmental concerns have motivated the researcher for alternate fuels, such as bio diesel that is obtained from vegetable oils. Therefore, bio diesel was synthesized from Rocket seed oil by base catalyzed transesterification with methanol. The physical parameters like dynamic viscosity (3.88 cp), specific gravity (0.893 g cm/sup 3/), kinematic viscosity (5.85 mm/sup 2/s/sup 1/)), density (0.877 g cm/sup 3/), cloud point (3 deg. C), flash point (110 deg. C) and acid number (0.07 mg KOH g/sup 1/) of the synthesized rocket seed oil bio diesel (RSOB) were determined and were found to be comparable with ASTM recommended values for diesels. Chemical composition of the bio diesels formed was determined by various techniques like Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy (/sup 1/H, 13/C) and gas chromatography-mass spectrometry (GCMS). The /sup 1/H NMR spectrum of RSOB is given. (Orig./A.B.)

  2. 13C direct detected COCO-TOCSY: A tool for sequence specific assignment and structure determination in protonless NMR experiments

    Science.gov (United States)

    Balayssac, Stéphane; Jiménez, Beatriz; Piccioli, Mario

    2006-10-01

    A novel experiment is proposed to provide inter-residue sequential correlations among carbonyl spins in 13C detected, protonless NMR experiments. The COCO-TOCSY experiment connects, in proteins, two carbonyls separated from each other by three, four or even five bonds. The quantitative analysis provides structural information on backbone dihedral angles ϕ as well as on the side chain dihedral angles of Asx and Glx residues. This is the first dihedral angle constraint that can be obtained via a protonless approach. About 75% of backbone carbonyls in Calbindin D 9K, a 75 aminoacid dicalcium protein, could be sequentially connected via a COCO-TOCSY spectrum. 49 3J values were measured and related to backbone ϕ angles. Structural information can be extended to the side chain orientation of aminoacids containing carbonyl groups. Additionally, long range homonuclear coupling constants, 4JCC and 5JCC, could be measured. This constitutes an unprecedented case for proteins of medium and small size.

  3. Complete {sup 1}H and {sup 13}C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

    Energy Technology Data Exchange (ETDEWEB)

    Johann, Susana; Smania Junior, Artur [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Microbiologia e Parasitologia. Lab. de Antibioticos; Pizzolatti, Moacir G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica; Schripsema, Jan; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Setor de Quimica de Produtos Naturais. Lab. de Quimica e Funcao de Proteinas e Peptideos (LQFPP); Branco, Alexsandro [Universidade Estadual de Feira de Santana, BA (Brazil). Dept. de Saude. Lab. de Fitoquimica]. E-mail: branco@uefs.br

    2007-06-15

    A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- ({sup 1}H NMR, {l_brace}{sup 1}H{r_brace} {sup -13}C NMR, and APT{sup -13}C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete {sup 1}H and {sup 13}C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated. (author)

  4. Internal motions in yeast phenylalanine transfer RNA from 13C NMR relaxation rates of modified base methyl groups: a model-free approach

    International Nuclear Information System (INIS)

    Internal motions at specific locations through yeast phenylalanine tRNA were measured by using nucleic acid biosynthetically enriched in 13C at modified base methyl groups. Carbon NMR spectra of isotopically enriched tRNA/sup Phe/ reveal 12 individual peaks for 13 of the 14 methyl groups known to be present. The two methyls of N2, N2-dimethylguanosine (m22G-26) have indistinguishable resonances, whereas the fourteenth methyl bound to ring carbon-11 of the hypermodified nucleoside 3' adjacent to the anticodon, wyosine (Y-37), does not come from the [methyl-13C] methionine substrate. Assignments to individual nucleosides within the tRNA were made on the basis of chemical shifts of the mononucleosides and correlation of 13C resonances with proton NMR chemical shifts via two-dimensional heteronuclear proton-carbon correlation spectroscopy. Values of 13C longitudinal relaxation (T1) and the nuclear Overhauser enhancements (NOE) were determined at 22.5, 75.5, and 118 MHz for tRNA/sup Phe/ in a physiological buffer solution with 10 mM MgCl2, at 220C. These data were used to extract two physical parameters that define the system with regard to fast internal motion: the generalized order parameters (S2) and effective correlation times (tau/sub e/) for internal motion of the C-H internuclear vectors. For all methyl groups the generalized order parameter varied from 0.057 to 0.108, compared with the value of 0.111 predicted for a rapidly spinning methyl group rigidly mounted on a spherical macromolecule. Values of tau/sub e/ ranged from 4 to 16 ps, generally shorter times than measured in other work for amino acid methyl groups in several proteins. Somewhat surprising was the finding that the two methyl esters terminating the Y-37 side chain have order parameters similar to those of other methyls in tRNA and only 25% less than that for a methyl directly bonded to the base

  5. Probing lipid-cholesterol interactions in DOPC/eSM/Chol and DOPC/DPPC/Chol model lipid rafts with DSC and (13)C solid-state NMR.

    Science.gov (United States)

    Fritzsching, Keith J; Kim, Jihyun; Holland, Gregory P

    2013-08-01

    The interaction between cholesterol (Chol) and phospholipids in bilayers was investigated for the ternary model lipid rafts, DOPC/eSM/Chol and DOPC/DPPC/Chol, with differential scanning calorimetry (DSC) and (13)C cross polarization magic angle spinning (CP-MAS) solid-state NMR. The enthalpy and transition temperature (Tm) of the Lα liquid crystalline phase transition from DSC was used to probe the thermodynamics of the different lipids in the two systems as a function of Chol content. The main chain (13)C (CH2)n resonance is resolved in the (13)C CP-MAS NMR spectra for the unsaturated (DOPC) and saturated (eSM or DPPC) chain lipid in the ternary lipid raft mixtures. The (13)C chemical shift of this resonance can be used to detect differences in chain ordering and overall interactions with Chol for the different lipid constituents in the ternary systems. The combination of DSC and (13)C CP-MAS NMR results indicate that there is a preferential interaction between SM and Chol below Tm for the DOPC/eSM/Chol system when the Chol content is ≤20mol%. In contrast, no preferential interaction between Chol and DPPC is observed in the DOPC/DPPC/Chol system above or below Tm. Finally, (13)C CP-MAS NMR resolves two Chol environments in the DOPC/eSM/Chol system below Tm at Chol contents >20mol% while, a single Chol environment is observed for DOPC/DPPC/Chol at all compositions.

  6. {sup 13}C-detected NMR experiments for automatic resonance assignment of IDPs and multiple-fixing SMFT processing

    Energy Technology Data Exchange (ETDEWEB)

    Dziekański, Paweł; Grudziąż, Katarzyna [University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre (Poland); Jarvoll, Patrik [Agilent Technologies (United Kingdom); Koźmiński, Wiktor; Zawadzka-Kazimierczuk, Anna, E-mail: anzaw@chem.uw.edu.pl [University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre (Poland)

    2015-06-15

    Intrinsically disordered proteins (IDPs) have recently attracted much interest, due to their role in many biological processes, including signaling and regulation mechanisms. High-dimensional {sup 13}C direct-detected NMR experiments have proven exceptionally useful in case of IDPs, providing spectra with superior peak dispersion. Here, two such novel experiments recorded with non-uniform sampling are introduced, these are 5D HabCabCO(CA)NCO and 5D HNCO(CA)NCO. Together with the 4D (HACA)CON(CA)NCO, an extension of the previously published 3D experiments (Pantoja-Uceda and Santoro in J Biomol NMR 59:43–50, 2014. doi: 10.1007/s10858-014-9827-1 10.1007/s10858-014-9827-1 ), they form a set allowing for complete and reliable resonance assignment of difficult IDPs. The processing is performed with sparse multidimensional Fourier transform based on the concept of restricting (fixing) some of spectral dimensions to a priori known resonance frequencies. In our study, a multiple-fixing method was developed, that allows easy access to spectral data. The experiments were tested on a resolution-demanding alpha-synuclein sample. Due to superior peak dispersion in high-dimensional spectrum and availability of the sequential connectivities between four consecutive residues, the overwhelming majority of resonances could be assigned automatically using the TSAR program.

  7. Soil organic matter dynamics as characterized with 1H and 13C solid-state NMR techniques

    Science.gov (United States)

    Jäger, Alex; Schwarz, Jette; Bertmer, Marko; Schaumann, Gabriele E.

    2010-05-01

    Soil organic matter (SOM) is a complex and heterogeneous matter. Characterization by solid-state NMR methods on 1H and 13C nuclei is therefore demanding. Our goal is to obtain information on the dynamic behaviour of soil samples and to study the influence of external parameters on both structure and dynamics. We regard water molecules to be the pivotal agent of soil dynamics by generating a network between organic matter via intermolecular hydrogen bonding, which leads to cross linking of organic matter and increases its rigidity. Although 1H solid-state NMR on non-rotating samples are not so commonly used for soil characterization, they enable the differentiation of proton mobilities via their linewidths which are resulting from differences in the dipole-dipole coupling strengths. Therefore, even weak molecular interactions such as hydrogen bonding can be differentiated and changes due to heat treatments and the short and long term behaviour followed. Though in principle a simple technique, static 1H measurements are complicated by several means, one of them is the high abundance in almost all matter including probe head material that has to be excluded for analysis. Finally, we selected 1H DEPTH [1] and Hahn-echo sequences to distinguish different mobilities in soil, mainly free moving water and water fixed in the soil matrix. After decomposition using Gaussian and Lorentzian lineshapes, the relative amounts of mobile and rigid water molecules can be obtained. By heating the samples above 100°C in sealed glass tubes, the proposed water network is destroyed and able to rebuild after cooling. This long term behaviour is studied on the course of months. Furthermore, the instant changes before and after heating are shown for a series of soil samples to characterize soils based on this water network model. To combine the information obtained on the 1H mobility with focus on water dynamics, 13C 2D WISE (wideline separation) measurements were done. This method yields 1

  8. Structure determination of uniformly 13C, 15N labeled protein using qualitative distance restraints from MAS solid-state 13C-NMR observed paramagnetic relaxation enhancement

    International Nuclear Information System (INIS)

    Magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) is a powerful method for structure determination of insoluble biomolecules. However, structure determination by MAS solid-state NMR remains challenging because it is difficult to obtain a sufficient amount of distance restraints owing to spectral complexity. Collection of distance restraints from paramagnetic relaxation enhancement (PRE) is a promising approach to alleviate this barrier. However, the precision of distance restraints provided by PRE is limited in solid-state NMR because of incomplete averaged interactions and intermolecular PREs. In this report, the backbone structure of the B1 domain of streptococcal protein G (GB1) has been successfully determined by combining the CS-Rosetta protocol and qualitative PRE restraints. The derived structure has a Cα RMSD of 1.49 Å relative to the X-ray structure. It is noteworthy that our protocol can determine the correct structure from only three cysteine-EDTA-Mn2+ mutants because this number of PRE sites is insufficient when using a conventional structure calculation method based on restrained molecular dynamics and simulated annealing. This study shows that qualitative PRE restraints can be employed effectively for protein structure determination from a limited conformational sampling space using a protein fragment library

  9. {sup 13}C NMR investigation of re-entrant antiferromagnetic states of (TMTTF){sub 2}SbF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Toshikazu; Iwase, Fumitatsu; Furukawa, Ko [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Satsukawa, Hidetaka; Takahashi, Toshihiro, E-mail: t-nk@ims.ac.j [Department of Physics, Gakushuin University, Mejiro, Toshima-ku, Tokyo 171-8588 (Japan)

    2009-03-01

    {sup 13}C nuclear magnetic resonance (NMR) investigations were performed on the one-dimensional organic conductor (TMTTF){sub 2}SbF{sub 6} to clarify its electronic properties in the proximity of the ground states. An abrupt broadening of {sup 13}C NMR absorption lines below 8 K (T{sub N} = 8 K), confirmed a long-range antiferromagnetic phase transition. Below T{sub N}, the absorption lines are composed of four distinct broad lines, indicating a commensurate magnetic structure. The amplitude of staggered magnetization, rho, is comparable to (TMTTF){sub 2}Br, and on the order of 0.1 mu{sub B} according to the splitting of {sup 13}C NMR lines at 3 K.

  10. Synthesis of 2,4,5,8-tetrabromotricyclo(4. 2. 2. 0/sup 1,5/)decane and determination of its structure by two-dimensional homonuclear and heteronuclear correlation /sup 1/H and /sup 13/C NMR spectroscopy and x-ray crystallographic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sekatsis, I.P.; Kemme, A.A.; Liepin' sh, E.E.; Bleidelis, Ya.Ya.; Gavars, M.P.; Raguel, B.P.; Polis, Ya.Yu.

    1988-08-10

    It is known that the bromination of endotricyclo(5.2.1.0/sup 2,6/)decane (I) with bromine in the presence of aluminum bromide leads to the formation of 1,3,5- and 1,3,6-tribromoadamantanes and 1,2,3,5,6,7-hexabromonaphthalene. In view of the complexity of the isomerization of the endo-decane (I) to adamantane the authors studied the bromination of (I) with bromine in order to detect the intermediate products of this isomerization. 2,4,5,8-Tetrabromotricyclo(4.2.2.0/sup 1,5/)decane was synthesized by the bromination of endo-tricyclo(5.2.1.0/sup 2,6/)decane, and its structure was determined by two-dimensional homonuclear and heteronuclear correlation NMR spectroscopy with full assignment of the signals and was confirmed by x-ray crystallographic analysis.

  11. Synthesis of D-[U-{sup 13}C]Glucal, D-[U-{sup 13}C] Galactal, and L-[U-{sup 13}C]Fucose for NMR structure studies of oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Wu, R.; Unkefer, C.J.; Silks, L.A. III [Los Alamos National Lab., NM (United States)

    1996-12-31

    The role of carbohydrates is well recognized in a variety of important biological phenomena such as cell surface recognition. Recent advances in carbohydrate chemistry, including the development of solid phase synthesis methods, have helped to provide significant quantities of material by offering general protocols for synthesis of well-defined, pure material. However, the study of the solution structure of oligosaccharides by nuclear magnetic resonance techniques have been hampered by the lack of enriched {sup 13}C material. In an effort to help alleviate this situation, we have been interested in the construction of the title compounds from a single economical carbon source, D-[U-{sup 13}C]glucose. Details of the syntheses will be provided.

  12. Methyl [13C]glucopyranosiduronic acids: effect of COOH ionization and exocyclic structure on NMR spin-couplings.

    Science.gov (United States)

    Zhang, Wenhui; Hu, Xiaosong; Carmichael, Ian; Serianni, Anthony S

    2012-11-01

    Methyl α- and β-D-glucopyranuronides singly labeled with (13)C at C1-C6 were prepared from the corresponding (13)C-labeled methyl D-glucopyranosides, and multiple NMR J-couplings (J(HH), J(CH), and J(CC)) were measured in their protonated and ionized forms in aqueous ((2)H(2)O) solution. Solvated density functional theory (DFT) calculations of J-couplings in structurally related model compounds were performed to determine how well the calculated J-couplings matched the experimental values in saccharides bearing an ionizable substituent. Intraring J(HH) values in both uronide anomers, including (3)J(H4,H5), are unaffected by solution pD, and COOH ionization exerts little effect on J(CH) and J(CC) except for (1)J(C1,H1), (1)J(C4,H4), (1)J(C5,H5), (1)J(C5,C6), and (2)J(C3,C5), where changes of up to 5 Hz were observed. Some of these changes are associated with changes in bond lengths upon ionization; in general, better agreement between theory and experiment was observed for couplings less sensitive to exocyclic C-O bond conformation. Titration of (1)H and (13)C chemical shifts, and some J-couplings, yielded a COOH pK(a) of 3.0 ± 0.1 in both anomers. DFT calculations suggest that substituents proximal to the exocyclic COOH group (i.e., the C4-O4 bond) influence the activation barrier to C5-C6 bond rotation due to transient intramolecular H-bonding. A comparison of J-couplings in the glucopyranuronides to corresponding J-couplings in the glucopyranosides showed that more pervasive changes occur upon conversion from a COOH to a CH(2)OH substituent at C6 than from COOH ionization within the uronides. Twelve J-couplings are affected, with the largest being (1)J(C5,C6) (∼18 Hz larger in the uronides), followed by (2)J(C6,H5) (∼2.5 Hz more negative in the uronides).

  13. Synthetic, Infrared And Nmr (1H And 13C) Spectral Studies Of N-(Substituted Phenyl)-Methanesulphonamides

    Science.gov (United States)

    Jayalakshmi, K. L.; Gowda, B. Thimme

    2004-08-01

    Twenty two N-(substituted phenyl)-methanesulphonamides of the general formula, CH3SO2NHR, where R = 4-XC6H4(X = H, CH3, F, Cl, Br or NO2), i-XC6H4(X=CH3, Cl orNO2 and i=2 or 3) and i, j-X2C6H3(i, j-X2 = 2,3-(CH3)2, 2,4-(CH3)2, 2,5-(CH3)2, 2,6-(CH3)2, 3,5-(CH3)2, 2,3-Cl2, 2,4- Cl2, 2,5-Cl2, 2,6-Cl2 or 3,4-Cl2) were prepared, characterized and their infrared spectra in the solid state and the NMR (1H and 13C) spectra in solution studied. The N-H stretching vibrations absorb in the range, 3298 - 3232 cm-1. Asymmetric and symmetric SO2 stretching vibrations appear as strong absorptions in the ranges, 1331 - 1317 cm-1 and 1157 - 1139 cm-1, respectively. The sulphonamides exhibit S-N stretching vibrations in the range, 926 - 833 cm-1. The effect of substitution in the phenyl ring in terms of electron withdrawing and electron donating groups is non-systematic. The 1H and 13C chemical shifts of N-(substituted phenyl)-methanesulphonamides are assigned to various protons and carbons of the compounds. Further, incremental shifts of the ring protons and carbons due to CH3SO2- and CH3SO2NH- groups in the N-(phenyl)-methanesulphonamide are computed and used to calculate the 1H and 13C chemical shifts of various protons and carbons of N-(substituted phenyl)-methanesulphonamides, by adding substituent contributions to the corresponding aromatic proton or carbon chemical shifts of either aniline, substituted anilines, benzene or substituted benzenes, in different ways, as per the principle of substituent addition. The computed values by different procedures agree well with each other and with the experimental chemical shifts. The correlation of these incremental shifts with the Hammett substituent parameters is poor.

  14. Other compounds isolated from Simira glaziovii and the {sup 1}H and {sup 13}C NMR chemical shift assignments of new 1-epi-castanopsol

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Marcelo F. de; Vieira, Ivo J. Curcino [Universidade Federal Rural do Rio de Janeiro, Seropedica, RJ (Brazil). Dept. de Quimica; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias Tecnologicas. Lab. de Ciencias Quimicas; Carvalho, Mario G. de, E-mail: mgeraldo@ufrrj.br [Universidade Federal do Rio de Janeiro (NPPN/UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisa em Produtos Naturais

    2012-07-01

    A new triterpene, 1-epi-castanopsol, besides eleven known compounds: sitosterol, stigmasterol, campesterol, lupeol, lupenone, simirane B, syringaresinol, scopoletin, isofraxidin, 6,7,8-trimethoxycoumarin and harman, were isolated from the wood of Simira glaziovii. The structures of the known compounds were defined by 1D, 2D {sup 1}H, {sup 13}C NMR spectra data analyses and comparison with literature data. The detailed spectral data analyses allowed the definition of the structure of the new 1-epi isomer of castanopsol and performance of {sup 1}H and {sup 13}C NMR chemical shift assignments. (author)

  15. Systematic Comparison of Sets of 13C NMR Spectra That Are Potentially Identical. Confirmation of the Configuration of a Cuticular Hydrocarbon from the Cane Beetle Antitrogus parvulus

    OpenAIRE

    Basar, Norazah; Damodaran, Krishnan; Liu, Hao; Morris, Gareth A.; Sirat, Hasnah M.; Thomas, Eric J.; Curran, Dennis P.

    2014-01-01

    A systematic process is introduced to compare 13C NMR spectra of two (or more) candidate samples of known structure to a natural product sample of unknown structure. The process is designed for the case where the spectra involved can reasonably be expected to be very similar, perhaps even identical. It is first validated by using published 13C NMR data sets for the natural product 4,6,8,10,16,18-hexamethyldocosane. Then the stereoselective total syntheses of two candidate isomers of the relat...

  16. A hybrid strategy for the preparation of 13C-labeled high-mannose-type oligosaccharides with terminal glucosylation for NMR study

    International Nuclear Information System (INIS)

    Stable isotopic labeling dramatically facilitates NMR studies of oligosaccharides. We previously established a method for overexpressing homogeneous high-mannose-type oligosaccharides with metabolic 13C labeling using genetically engineered yeast cells. To extend the applicability of this methodology, we combined it with chemoenzymatic synthesis using a specific glucosyl transferase. Our hybrid approach has enabled the production of a uniformly and selectively 13C-labeled dodecasaccharide with terminal glucosylation, a signal recognized by molecular chaperones, providing useful NMR tools for detailed conformational analyses. (author)

  17. Chemical constituents from Ouratea floribunda: complete {sup 1} H and {sup 13} C NMR assignments of atranorin and its new acetyl derivative

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Mario G. de; Carvalho, Geizi J.A. de [Universidade Federal Rural do Rio de Janeiro, RJ (Brazil). Dept. de Quimica; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Setor de Quimica de Produtos Naturais

    2000-04-01

    Chromatographic fractionation of the hexane extract from the wood of Ouratea floribunda (Ochnaceae) afforded friedelin (1), friedelanol (2), lupeol (3) and the depside atranorin (4). The structure elucidation of the isolated compounds was performed by spectrometric analysis involving comparison with literature data. The unambiguous assignments of {sup 1}H and {sup 13} C NMR data of atranorin 4 and its acetyl derivative 4a are reported for the first time and involved {sup 1}H-{sup 1} homonuclear (COSY and NOESY) and {sup 1} H-{sup 13} C heteronuclear (HMQC and HMBC) NMR experiments. (author)

  18. Determination of Dihydrobenzoacridinone Structures by NMR, IR, and UV Spectroscopy and Mass Spectrometry

    Science.gov (United States)

    Kozlov, N. G.; Zhiharko, Yu. D.; Skakovsky, E. D.; Baranovsky, A. V.; Ogorodnikova, M. M.; Basalaeva, L. I.

    2016-01-01

    Condensation of 2-naphthylamine, aromatic aldehydes, and dimedone was found to produce 9,10-dihydrobenzo[a] acridin-11-one derivatives according to PMR, 13C NMR, and IR spectroscopy and mass spectrometry. Correlation spectroscopy showed that the carbonyl in the synthesized dihydrobenzoacridinone derivatives was located on C11.

  19. 13C NMR detects conformational change in the 100-kD membrane transporter ClC-ec1

    International Nuclear Information System (INIS)

    CLC transporters catalyze the exchange of Cl− for H+ across cellular membranes. To do so, they must couple Cl− and H+ binding and unbinding to protein conformational change. However, the sole conformational changes distinguished crystallographically are small movements of a glutamate side chain that locally gates the ion-transport pathways. Therefore, our understanding of whether and how global protein dynamics contribute to the exchange mechanism has been severely limited. To overcome the limitations of crystallography, we used solution-state 13C-methyl NMR with labels on methionine, lysine, and engineered cysteine residues to investigate substrate (H+) dependent conformational change outside the restraints of crystallization. We show that methyl labels in several regions report H+-dependent spectral changes. We identify one of these regions as Helix R, a helix that extends from the center of the protein, where it forms the part of the inner gate to the Cl−-permeation pathway, to the extracellular solution. The H+-dependent spectral change does not occur when a label is positioned just beyond Helix R, on the unstructured C-terminus of the protein. Together, the results suggest that H+ binding is mechanistically coupled to closing of the intracellular access-pathway for Cl−

  20. 1H, 13C and 15N NMR spectral and X-ray structural studies of 2-arylsulfonylamino-5-chlorobenzophenones

    International Nuclear Information System (INIS)

    Six 2-(4-R-phenylsulfonylamino)-5-chlorobenzophenones were prepared and their 1H, 13C and 15N NMR spectra recorded and assigned. The dependence between the chemical shift of the amide proton and Hammett σ substituent constants is of the V type. Substituent effect on the chemical shift of the amide nitrogen atom was found insignificant. X-ray analysis shows that the terminal benzene rings in 2-(4-nitro-phenylsulfonylamino)-5-chlorobenzophenones are located close to each other. They are not, however, parallel, dihedral angle between them being equal to 10.86 deg (MP2/6-31G**//HF/6-31G** ab initio calculations show this to be 20.44 deg). This shows that the mutual orientation of two benzene rings in the molecule of this compound is caused by the π-π stacking. It is additionally reinforced by the intramolecular NH...O=C hydrogen bond. Except the dihedral angle between the benzene rings, X-ray determined structure of 2-(4-nitro-phenylsulfonylamino)-5-chlorobenzophenones is very similar to this optimized by the ab initio calculations. (author)

  1. 1D 13C-NMR Data as Molecular Descriptors in Spectra — Structure Relationship Analysis of Oligosaccharides

    Directory of Open Access Journals (Sweden)

    Florbela Pereira

    2012-03-01

    Full Text Available Spectra-structure relationships were investigated for estimating the anomeric configuration, residues and type of linkages of linear and branched trisaccharides using 13C-NMR chemical shifts. For this study, 119 pyranosyl trisaccharides were used that are trimers of the α or β anomers of D-glucose, D-galactose, D-mannose, L-fucose or L-rhamnose residues bonded through a or b glycosidic linkages of types 1→2, 1→3, 1→4, or 1→6, as well as methoxylated and/or N-acetylated amino trisaccharides. Machine learning experiments were performed for: (1 classification of the anomeric configuration of the first unit, second unit and reducing end; (2 classification of the type of first and second linkages; (3 classification of the three residues: reducing end, middle and first residue; and (4 classification of the chain type. Our previously model for predicting the structure of disaccharides was incorporated in this new model with an improvement of the predictive power. The best results were achieved using Random Forests with 204 di- and trisaccharides for the training set—it could correctly classify 83%, 90%, 88%, 85%, 85%, 75%, 79%, 68% and 94% of the test set (69 compounds for the nine tasks, respectively, on the basis of unassigned chemical shifts.

  2. {sup 13}C NMR detects conformational change in the 100-kD membrane transporter ClC-ec1

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Sherwin J.; Cheng, Ricky C.; Chew, Thomas A.; Khantwal, Chandra M. [Stanford University School of Medicine, Department of Molecular & Cellular Physiology (United States); Liu, Corey W. [Stanford University School of Medicine, Stanford Magnetic Resonance Laboratory (United States); Gong, Shimei; Nakamoto, Robert K. [University of Virginia, Department of Molecular Physiology and Biological Physics (United States); Maduke, Merritt, E-mail: maduke@stanford.edu [Stanford University School of Medicine, Department of Molecular & Cellular Physiology (United States)

    2015-04-15

    CLC transporters catalyze the exchange of Cl{sup −} for H{sup +} across cellular membranes. To do so, they must couple Cl{sup −} and H{sup +} binding and unbinding to protein conformational change. However, the sole conformational changes distinguished crystallographically are small movements of a glutamate side chain that locally gates the ion-transport pathways. Therefore, our understanding of whether and how global protein dynamics contribute to the exchange mechanism has been severely limited. To overcome the limitations of crystallography, we used solution-state {sup 13}C-methyl NMR with labels on methionine, lysine, and engineered cysteine residues to investigate substrate (H{sup +}) dependent conformational change outside the restraints of crystallization. We show that methyl labels in several regions report H{sup +}-dependent spectral changes. We identify one of these regions as Helix R, a helix that extends from the center of the protein, where it forms the part of the inner gate to the Cl{sup −}-permeation pathway, to the extracellular solution. The H{sup +}-dependent spectral change does not occur when a label is positioned just beyond Helix R, on the unstructured C-terminus of the protein. Together, the results suggest that H{sup +} binding is mechanistically coupled to closing of the intracellular access-pathway for Cl{sup −}.

  3. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid

    Science.gov (United States)

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

  4. Oligomeric complexes of some heteroaromatic ligands and aromatic diamines with rhodium and molybdenum tetracarboxylates: 13C and 15N CPMAS NMR and density functional theory studies.

    Science.gov (United States)

    Leniak, Arkadiusz; Kamieński, Bohdan; Jaźwiński, Jarosław

    2015-05-01

    Seven new oligomeric complexes of 4,4'-bipyridine; 3,3'-bipyridine; benzene-1,4-diamine; benzene-1,3-diamine; benzene-1,2-diamine; and benzidine with rhodium tetraacetate, as well as 4,4'-bipyridine with molybdenum tetraacetate, have been obtained and investigated by elemental analysis and solid-state nuclear magnetic resonance spectroscopy, (13)C and (15)N CPMAS NMR. The known complexes of pyrazine with rhodium tetrabenzoate, benzoquinone with rhodium tetrapivalate, 4,4'-bipyridine with molybdenum tetrakistrifluoroacetate and the 1 : 1 complex of 2,2'-bipyridine with rhodium tetraacetate exhibiting axial-equatorial ligation mode have been obtained as well for comparison purposes. Elemental analysis revealed 1 : 1 complex stoichiometry of all complexes. The (15)N CPMAS NMR spectra of all new complexes consist of one narrow signal, indicating regular uniform structures. Benzidine forms a heterogeneous material, probably containing linear oligomers and products of further reactions. The complexes were characterized by the parameter complexation shift Δδ (Δδ = δcomplex  - δligand). This parameter ranged from around -40 to -90 ppm in the case of heteroaromatic ligands, from around -12 to -22 ppm for diamines and from -16 to -31 ppm for the complexes of molybdenum tetracarboxylates with 4,4'-bipyridine. The experimental results have been supported by a density functional theory computation of (15)N NMR chemical shifts and complexation shifts at the non-relativistic Becke, three-parameter, Perdew-Wang 91/[6-311++G(2d,p), Stuttgart] and GGA-PBE/QZ4P levels of theory and at the relativistic scalar and spin-orbit zeroth order regular approximation/GGA-PBE/QZ4P level of theory. Nucleus-independent chemical shifts have been calculated for the selected compounds. PMID:25614975

  5. NMR Spectroscopy and Its Value: A Primer

    Science.gov (United States)

    Veeraraghavan, Sudha

    2008-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is widely used by chemists. Furthermore, the use of NMR spectroscopy to solve structures of macromolecules or to examine protein-ligand interactions is popular. Yet, few students entering graduate education in biological sciences have been introduced to this method or its utility. Over the last six…

  6. Identification, synthesis and characterization of an unknown process related impurity in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI-IT/MS, 1H, 13C and 1H-1H COSY NMR

    Institute of Scientific and Technical Information of China (English)

    Saji Thomas; Saroj Kumar Paul; Subhash Chandra Joshi; Vineet Kumar; Ashutosh Agarwal; Dharam Vir

    2014-01-01

    A new impurity was detected during high performance liquid chromatographic (HPLC) analysis of eslicarbazepine acetate active pharmaceutical ingredient. The structure of unknown impurity was postulated based on liquid chromatography mass spectrometry using electrospray ionization and ion trap analyzer (LC/ESI-IT/MS) analysis. Proposed structure of impurity was unambiguously confirmed by synthesis followed by characterization using 1H, 13C nuclear magnetic resonance spectrometry (NMR), 1H-1H correlation spectro-scopy (COSY) and infrared spectroscopy (IR). Based on the spectroscopic and spectrometric data, unknown impurity was characterized as 5-carbamoyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl propionate.

  7. Identification, synthesis and characterization of an unknown process related impurity in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI–IT/MS, 1H, 13C and 1H–1H COSY NMR

    Directory of Open Access Journals (Sweden)

    Saji Thomas

    2014-10-01

    Full Text Available A new impurity was detected during high performance liquid chromatographic (HPLC analysis of eslicarbazepine acetate active pharmaceutical ingredient. The structure of unknown impurity was postulated based on liquid chromatography mass spectrometry using electrospray ionization and ion trap analyzer (LC/ESI–IT/MS analysis. Proposed structure of impurity was unambiguously confirmed by synthesis followed by characterization using 1H, 13C nuclear magnetic resonance spectrometry (NMR, 1H–1H correlation spectroscopy (COSY and infrared spectroscopy (IR. Based on the spectroscopic and spectrometric data, unknown impurity was characterized as 5-carbamoyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl propionate.

  8. Atribuição dos deslocamentos químicos dos átomos de ¹H e 13C do acetato de acantoaustralida 1H and 13C NMR assignments of acanthoaustralide-1-O-Acetate

    Directory of Open Access Journals (Sweden)

    Lúcia R. Rocha Martins

    2006-12-01

    Full Text Available Do extrato hidroetanólico das partes aéreas de Acanthospermum australe (Asteraceae foram identificados uma lactona diterpênica, o acetato de acantoaustralida (1 e dois flavonoides: quercetina (2 e crisosplenol D (3. As estruturas foram identificadas através de técnicas espectroscópicas de RMN de ¹H e 13C, gHSQC, gHMBC, TOCSY, gNOESY, EM e pela comparação com dados da literatura.From the hydroethanolic extract of the aerial parts of Acanthospermum australe (Asteraceae a diterpene lactone, acanthoaustralide-1-O-Acetate (1 and two flavonoids: quercetin (2 and chrysosplenol D (3 were identified. The structures were determined though the use of spectroscopic techniques such as NMR (¹H, 13C{¹H}, gHSQC, gHMBC, TOCSY, gNOESY, MS and compared with the literature data.

  9. A Discovery-Based Hydrochlorination of Carvone Utilizing a Guided-Inquiry Approach to Determine the Product Structure from [superscript 13]C NMR Spectra

    Science.gov (United States)

    Pelter, Michael W.; Walker, Natalie M.

    2012-01-01

    This experiment describes a discovery-based method for the regio- and stereoselective hydrochlorination of carvone, appropriate for a 3-h second-semester organic chemistry laboratory. The product is identified through interpretation of the [superscript 13]C NMR and DEPT spectra are obtained on an Anasazi EFT-60 at 15 MHz as neat samples. A…

  10. A study of the molecular conformations and the vibrational, 1H and 13C NMR spectra of the anticancer drug tamoxifen and triphenylethylene

    Science.gov (United States)

    Badawi, Hassan M.; Khan, Ibrahim

    2016-08-01

    The structural stability and the vibrational spectra of the anticancer drug tamoxifen and triphenylethylene were investigated by the DFT B3LYP/6-311G (d,p) calculations. Tamoxifen and triphenylethylene were predicted to exist predominantly as non-planar structures. The vibrational frequencies and the 1H and 13C NMR chemical shifts of the low energy structures of tamoxifen and triphenylethylene were computed at the DFT B3LYP level of theory. Complete vibrational assignments were provided by combined theoretical and experimental data of tamoxifen and triphenylethylene. The 1H and 13C NMR spectra of both molecules were interpreted by experimental and DFT calculated chemical shifts of the two molecules. The RMSD between experimental and theoretical 1H and 13C chemical shifts for tamoxifen is 0.29 and 4.72 ppm, whereas for triphenylethylene, it is 0.16 and 2.70 ppm, respectively.

  11. Analysis of metabolic disorders of dairy cows employing multidimensional and multinuclear NMR spectroscopy

    OpenAIRE

    Klein, Matthias S.

    2011-01-01

    In this thesis, metabolism profiles of different diseases were measured in body fluids and tissues using high-resolution one-dimensional (1D) and two-dimensional (2D) proton (1H) and carbon-13 (13C) nuclear magnetic resonance (NMR) spectroscopy at natural 13C abundance. Protocols for measuring and quantifying low-molecular weight organic molecules in urine, milk, plasma, serum and tissue extracts were established and validated by comparison with established analytical techniques such as gas c...

  12. Paramagnetic 13C and 15N NMR analyses of the push and pull effects in cytochrome c peroxidase and Coprinus cinereus peroxidase variants: functional roles of highly conserved amino acids around heme.

    Science.gov (United States)

    Nonaka, Daisuke; Wariishi, Hiroyuki; Welinder, Karen G; Fujii, Hiroshi

    2010-01-12

    Paramagnetic (13)C and (15)N nuclear magnetic resonance (NMR) spectroscopy of heme-bound cyanide ((13)C(15)N) was applied to 11 cytochrome c peroxidase (CcP) and Coprinus cinereus peroxidase (CIP) mutants to investigate contributions to the push and pull effects of conserved amino acids around heme. The (13)C and (15)N NMR data for the distal His and Arg mutants indicated that distal His is the key amino acid residue creating the strong pull effect and that distal Arg assists. The mutation of distal Trp of CcP to Phe, the amino acid at this position in CIP, changed the push and pull effects so they resembled those of CIP, whereas the mutation of distal Phe of CIP to Trp changed this mutant to become CcP-like. The (13)C NMR shifts for the proximal Asp mutants clearly showed that the proximal Asp-His hydrogen bonding strengthens the push effect. However, even in the absence of a hydrogen bond, the push effect of proximal His in peroxidase is significantly stronger than in globins. Comparison of these NMR data with the compound I formation rate constants and crystal structures of these mutants showed that (1) the base catalysis of the distal His is more critical for rapid compound I formation than its acid catalysis, (2) the primary function of the distal Arg is to maintain the distal heme pocket in favor of rapid compound I formation via hydrogen bonding, and (3) the push effect is the major contributor to the differential rates of compound I formation in wild-type peroxidases.

  13. Tracing bacterial metabolism using multi-nuclear (1H, 2H, and 13C) Solid State NMR: Realizing an Idea Initiated by James Scott

    Science.gov (United States)

    Cody, G.; Fogel, M. L.; Jin, K.; Griffen, P.; Steele, A.; Wang, Y.

    2011-12-01

    Approximately 6 years ago, while at the Geophysical Laboratory, James Scott became interested in the application of Solid State Nuclear Magnetic Resonance Spectroscopy to study bacterial metabolism. As often happens, other experiments intervened and the NMR experiments were not pursued. We have revisited Jame's question and find that using a multi-nuclear approach (1H, 2H, and 13C Solid State NMR) on laboratory cell culture has some distinct advantages. Our experiments involved batch cultures of E. coli (MG1655) harvested at stationary phase. In all experiments the growth medium consisted of MOPS medium for enterobacteria, where the substrate is glucose. In one set of experiments, 10 % of the water was D2O; in another 10 % of the glucose was per-deuterated. The control experiment used both water and glucose at natural isotopic abundance. A kill control of dead E. coli immersed in pure D2O for an extended period exhibited no deuterium incorporation. In both deuterium enriched experiments, considerable incorporation of deuterium into E. coli's biomolecular constituents was detected via 2H Solid State NMR. In the case of the D2O enriched experiment, 58 % of the incorporated deuterium is observed in a sharp peak at a frequency of 0.31 ppm, consistent with D incorporation in the cell membrane lipids, the remainder is observed in a broad peak at a higher frequency (centered at 5.4 ppm, but spanning out to beyond 10 ppm) that is consistent with D incorporation into predominantly DNA and RNA. In the case of the D-glucose experiments, 61 % of the deuterium is observed in a sharp resonance peak at 0.34 ppm, also consistent with D incorporation into membrane lipids, the remainder of the D is observed at a broad resonance peak centered at 4.3 ppm, consistent with D enrichment in glycogen. Deuterium abundance in the E. coli cells grown in 10 % D2O is nearly 2X greater than that grown with 10 % D-glucose. Very subtle differences are observed in both the 1H and 13C solid

  14. Global Fold of Human Cannabinoid Type 2 Receptor Probed by Solid-State 13C-, 15N-MAS NMR and Molecular Dynamics Simulations

    OpenAIRE

    Kimura, Tomohiro; Vukoti, Krishna; Lynch, Diane L.; Hurst, Dow P.; Grossfield, Alan; Pitman, Michael C.; Reggio, Patricia H.; Yeliseev, Alexei A.; Gawrisch, Klaus

    2013-01-01

    The global fold of human cannabinoid type 2 (CB2) receptor in the agonist-bound active state in lipid bilayers was investigated by solid-state 13C- and 15N magic-angle spinning (MAS) NMR, in combination with chemical-shift prediction from a structural model of the receptor obtained by microsecond-long molecular dynamics (MD) simulations. Uniformly 13C-, and 15N-labeled CB2 receptor was expressed in milligram quantities by bacterial fermentation, purified, and functionally reconstituted into l...

  15. Biomass production of site selective {sup 13}C/{sup 15}N nucleotides using wild type and a transketolase E. coli mutant for labeling RNA for high resolution NMR

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Chandar S.; Luo Yiling; Chen Bin; Eldho, Nadukkudy V.; Dayie, T. Kwaku, E-mail: dayie@umd.edu [Center for Biomolecular Structure and Organization, University of Maryland, Department of Chemistry and Biochemistry (United States)

    2012-02-15

    Characterization of the structure and dynamics of nucleic acids by NMR benefits significantly from position specifically labeled nucleotides. Here an E. coli strain deficient in the transketolase gene (tktA) and grown on glucose that is labeled at different carbon sites is shown to facilitate cost-effective and large scale production of useful nucleotides. These nucleotides are site specifically labeled in C1 Prime and C5 Prime with minimal scrambling within the ribose ring. To demonstrate the utility of this labeling approach, the new site-specific labeled and the uniformly labeled nucleotides were used to synthesize a 36-nt RNA containing the catalytically essential domain 5 (D5) of the brown algae group II intron self-splicing ribozyme. The D5 RNA was used in binding and relaxation studies probed by NMR spectroscopy. Key nucleotides in the D5 RNA that are implicated in binding Mg{sup 2+} ions are well resolved. As a result, spectra obtained using selectively labeled nucleotides have higher signal-to-noise ratio compared to those obtained using uniformly labeled nucleotides. Thus, compared to the uniformly {sup 13}C/{sup 15}N-labeled nucleotides, these specifically labeled nucleotides eliminate the extensive {sup 13}C-{sup 13}C coupling within the nitrogenous base and ribose ring, give rise to less crowded and more resolved NMR spectra, and accurate relaxation rates without the need for constant-time or band-selective decoupled NMR experiments. These position selective labeled nucleotides should, therefore, find wide use in NMR analysis of biologically interesting RNA molecules.

  16. NMR spectroscopy assists synthetic fuels research

    Energy Technology Data Exchange (ETDEWEB)

    Cookson, D.J.; Smith, B.E.

    1983-01-01

    NMR spectroscopy has proved to be a useful and versatile technique for the study of synthetic fuels feedstocks, catalysts, process intermediates and final products. Some applications of the technique to coal and gas conversion research are illustrated and discussed.

  17. Landmarks in the application of 13C-magnetic resonance spectroscopy to studies of neuronal/glial relationships.

    Science.gov (United States)

    Bachelard, H

    1998-01-01

    The development of the use of carbon isotopes as metabolic tracers is briefly described. 13C-labelled precursors (13CO2, 13CH4) first became available in 1940 and were studied in microorganisms, but their use was limited by very low enrichments and lack of suitable analytical equipment. More success was achieved with 11C and especially 14C, as these radioactive tracers did not need to be highly enriched. Although the stable 13C isotope can be used at a low percentage enrichment in mass spectrometry, its application to magnetic resonance spectroscopy (MRS) requires very highly enriched precursors, due to its low natural abundance and low sensitivity. Despite such limitations, however, the great advantage of 13C-MRS lies in its exquisite chemical specificity, in that labelling of different carbon atoms can be distinguished within the same molecule. Effective exploitation became feasible in the early 1970s with the advent of stable instruments, Fourier transform 13C-MRS, and the availability of highly enriched precursors. Reports of its use in brain research began to appear in the mid-1980s. The applications of 13C isotopomer analysis to research on neuronal/glial relationships are reviewed. The presence of neighbouring 13C-labelled atoms affects the appearance of the resonances (splitting due to C-C coupling), and so allows for unique quantification of rates through different and possibly competing pathways. Isotopomer patterns in resonances labelled from a combination of [1-13C]glucose and [1, 2-13C2]acetate have revealed aspects of neuronal/glial metabolic trafficking on depolarization and under hypoxic conditions in vitro. This approach has now been applied to in vivo studies on inhibition of glial metabolism using fluoroacetate. The results confirm the glial specificity of the toxin and demonstrate that it does not affect entry of acetate. When the glial TCA cycle is inhibited, the ability of the glia to participate in the glutamate/glutamine cycle remains

  18. Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using 13C NMR in the solid state and solution along with single crystal X‐ray diffraction

    OpenAIRE

    Steiner, Emilie; Mathew, Renny; Zimmermann, Iwan; Brotin, Thierry; Edén, Mattias; Kowalewski, Jozef

    2015-01-01

    Host‐guest complexes between cryptophane‐A analogue with butoxy groups (cryptophane‐But) and chloromethanes (chloroform, dichloromethane) were investigated in the solid state by means of magic‐angle spinning 13C NMR spectroscopy. The separated local fields method with 13C‐1H dipolar recoupling was used to determine the residual dipolar coupling for the guest molecules encaged in the host cavity. In the case of chloroform guest, the residual dipolar interaction was estimated to be about 19 kHz...

  19. 1H and 13C NMR Assignments for Amlodipine and Risperidone%氨氯地平和利培酮的1H和13C核磁共振信号归属

    Institute of Scientific and Technical Information of China (English)

    杨春晖; 李勤; 刘雪辉; 赵兴凯; 崔育新

    2004-01-01

    目的对氨氯地平和利培酮两种药物分子进行核磁共振研究.方法应用一维和二维核磁共振技术,如gCOSY, gHSQC和gHMBC.结果对两种药物分子核磁共振氢谱和碳谱进行了归属,氟碳间的耦合常数对碳谱的解析提供了有利的证据.结论通过核磁共振化学位移和耦合常数的分析,确证了氨氯地平和利培酮两种药物分子的化学结构.%Aim To investigate the NMR spectroscopy of amlodipine and risperidone.Methods 1D NMR and 2D NMR experimental techniques of gCOSY, gHSQC and gHMBC were wsed.Results The assignments of the 1H and 13C NMR data for the two drugs were performed and confirmed by the evidence of JHF and JCF.Conclusion The structures of amlodipine and risperidone were confirmed by careful analysis of regular 1D and 2D NMR spectroscopy.

  20. Systematic comparison of sets of (13)C NMR spectra that are potentially identical. Confirmation of the configuration of a cuticular hydrocarbon from the cane beetle Antitrogus parvulus.

    Science.gov (United States)

    Basar, Norazah; Damodaran, Krishnan; Liu, Hao; Morris, Gareth A; Sirat, Hasnah M; Thomas, Eric J; Curran, Dennis P

    2014-08-15

    A systematic process is introduced to compare (13)C NMR spectra of two (or more) candidate samples of known structure to a natural product sample of unknown structure. The process is designed for the case where the spectra involved can reasonably be expected to be very similar, perhaps even identical. It is first validated by using published (13)C NMR data sets for the natural product 4,6,8,10,16,18-hexamethyldocosane. Then the stereoselective total syntheses of two candidate isomers of the related 4,6,8,10,16-pentamethyldocosane natural product are described, and the process is applied to confidently assign the configuration of the natural product as (4S,6R,8R,10S,16S). This is accomplished even though the chemical shift differences between this isomer and its (16R)-epimer are only ±5-10 ppb (±0.005-0.01 ppm). PMID:25019530

  1. Use of 2,6-dimethyl-γ-pyrone as a 13C NMR indicator for estimating the activity of heteropoly acid solutions

    International Nuclear Information System (INIS)

    13C NMR of solutions containing 2,6-dimethyl-γ-pyrone as a 13C NMR indicator were used to estimate the acidity of aqueous solutions of ordinary acids (HCl, HNO3, HClO4) and heteropoly acids (HPA) of the composition SiW12, PMo10V2, P2W18, PW12, PW11Zr, PMo12, P2Mo18, SiMo12, As2W21, PMo6W6, B3W39, P2W21, PW11Ti. In the concentration range [H+] = 0-1.7 mol/l the change in signal positions in the spectra reaches 10 ppm, which permits using the method for comparing the solution acidity of ordinary acids. In HPA solutions indicator-HPA anion and probably, indicator-H+-HPA anion interactions were detected. It suggests the conclusion that the indicator method is inapplicable for ascertaining the acidity in HPA solution

  2. Mechanism of formation of humus coatings on mineral surfaces 3. Composition of adsorbed organic acids from compost leachate on alumina by solid-state 13C NMR

    Science.gov (United States)

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.

    1996-01-01

    The adsorption of compost leachate DOC on alumina is used as a model for elucidation of the mechanism of formation of natural organic coatings on hydrous metal oxide surfaces in soils and sediments. Compost leachate DOC is composed mainly of organic acid molecules. The solid-state 13C NMR spectra of these organic acids indicate that they are very similar in composition to aquatic humic substances. Changes in the solid-state 13C NMR spectra of compost leachate DOC fractions adsorbed on alumina indicate that the DOC molecules are most likely adsorbed on metal oxide surfaces through a combination of polar and hydrophobic interaction mechanisms. This combination of polar and hydrophobic mechanism leads to the formation of bilayer coatings of the leachate molecules on the oxide surfaces.

  3. Thz Spectroscopy of 13C Isotopic Species of a "weed": Acetaldehyde

    Science.gov (United States)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.

    2011-06-01

    Our studies of the isotopic species of 13C and D isotopologues of methyl formate (HCOOCH_3), have allowed the detection of more than 600 lines in Orion. This confirms that many observed U-lines are coming from isotopic species of one of the most abundant molecules in space. Since its first detection in 1976 in SgrB2 and in Orion A, acetaldehyde (CH_3CHO) was detected in many other numerous objects. If its deuterated species (CD_3CHO and CH_3CDO) have been previously studied in the millimeterwave range, the data concerning the 13C species are limited to few lines measured in 1957 up to 40 GHz. In this context we decided to study the 13C species of acetaldehyde. Acetaldehyde molecule displays a large amplitude motion: the hindered rotation of the methyl group with respect to the rest of the molecule. The analysis is performed with the Rho Axis Method. Recent versions of the codes include high orders term in order to reproduce the observed frequencies for large quantum numbers values as J-values as high as 70a,b,. Measurements and analysis of the rotational spectra of 13C isotopic species are in progress in Lille with a solid-state submillimetre-wave spectrometer (50-950 GHz), the first results will be presented. This work is supported by the contract ANR-08-BLAN-0054 and by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS). Carvajal, M.; Margulès, L.; Tercero, B.; et al.A&A 500, (2009) 1109 Margulès, L.; Huet, T. R.; Demaison J.; et al.,ApJ 714, (2010) 1120. Ikeda, M.; Ohishi, M.; Nummelin, A.; et al., ApJ, 560, (2001) 792 Kleiner, I.; Lopez, J.-C.; Blanco, S.; et al.J. Mol. Spectrosc. 197, (1999) 275 Elkeurti M.; Coudert, L. H.; Medvedev, I. R.; et al.J. Mol. Spectrosc. 263, (2010) 145 Kilb, R.W.; Lin, C.C.; and Wilson, E.B.J. Chem. Phys. 26, (1957) 1695 Kleiner, I. J. Mol. Spectrosc. 260, (2010) 1 Ilyushin, V.V.; Kryvda, A; and Alekseev, E;J. Mol. Spectrosc. 255, (2009) 32

  4. Effects of stereoelectronic interactions on the relativistic spin-orbit and paramagnetic components of the (13)C NMR shielding tensors of dihaloethenes.

    Science.gov (United States)

    Viesser, Renan V; Ducati, Lucas C; Autschbach, Jochen; Tormena, Cláudio F

    2015-07-15

    In this study, stereoelectronic interactions were considered to explain the experimental difference in the magnitude of the known heavy-atom effect on the (13)C NMR chemical shifts in cis- and trans-1,2-dihaloethene isomers (halo = F, Cl, Br or I). The experimental values were compared to the calculated values with various DFT functionals using both the nonrelativistic approach (NR) and the relativistic approximations SR-ZORA (SR) and SO-ZORA (SO). NBO and NLMO contributions to the (13)C NMR shielding tensors were determined to assess which stereoelectronic interactions have a more important effect on the shielding tensor in each principal axis system (PAS) coordinate. These analyses associated with the orbital rotation model and the HOMO-LUMO energy gap enable rationalization of trends between cis and trans isomers from fluorine to iodine derivatives. Both paramagnetic and SO shielding terms were responsible for the observed trends. It was possible to conclude that the steric interactions between the two iodine atoms and the hyperconjugative interactions involving the halogen lone pairs (LP(X)) and πC[double bond, length as m-dash]C*, σC[double bond, length as m-dash]C* and σC-X* antibonding orbitals are responsible for the lower (13)C NMR shielding for the cis isomers of the bromine and the iodine compounds than that of the trans isomers.

  5. Dimethyl sulfone in human cerebrospinal fluid and blood plasma confirmed by one-dimensional (1)H and two-dimensional (1)H-(13)C NMR.

    NARCIS (Netherlands)

    Engelke, U.F.H.; Tangerman, A.; Willemsen, M.A.A.P.; Moskau, D.; Loss, S.; Mudd, S.H.; Wevers, R.A.

    2005-01-01

    (1)H-NMR spectroscopy at 500 MHz was used to confirm that a previously unidentified singlet resonance at 3.14 ppm in the spectra of cerebrospinal fluid and plasma samples corresponds to dimethyl sulfone (DMSO(2)). A triple resonance inverse cryogenic NMR probe, with pre-amplifier and the RF-coils co

  6. Hydrogen Bonding Interactions in Amorphous Indomethacin and Its Amorphous Solid Dispersions with Poly(vinylpyrrolidone) and Poly(vinylpyrrolidone-co-vinyl acetate) Studied Using (13)C Solid-State NMR.

    Science.gov (United States)

    Yuan, Xiaoda; Xiang, Tian-Xiang; Anderson, Bradley D; Munson, Eric J

    2015-12-01

    Hydrogen bonding interactions in amorphous indomethacin and amorphous solid dispersions of indomethacin with poly(vinylpyrrolidone), or PVP, and poly(vinylpyrrolidone-co-vinyl acetate), or PVP/VA, were investigated quantitatively using solid-state NMR spectroscopy. Indomethacin that was (13)C isotopically labeled at the carboxylic acid carbon was used to selectively analyze the carbonyl region of the spectrum. Deconvolution of the carboxylic acid carbon peak revealed that 59% of amorphous indomethacin molecules were hydrogen bonded through carboxylic acid cyclic dimers, 15% were in disordered carboxylic acid chains, 19% were hydrogen bonded through carboxylic acid and amide interactions, and the remaining 7% were free of hydrogen bonds. The standard dimerization enthalpy and entropy of amorphous indomethacin were estimated to be -38 kJ/mol and -91 J/(mol · K), respectively, using polystyrene as the "solvent". Polymers such as PVP and PVP/VA disrupted indomethacin self-interactions and formed hydrogen bonds with the drug. The carboxylic acid dimers were almost completely disrupted with 50% (wt) of PVP or PVP/VA. The fraction of disordered carboxylic acid chains also decreased as the polymer content increased. The solid-state NMR results were compared with molecular dynamics (MD) simulations from the literature. The present work highlights the potential of (13)C solid-state NMR to detect and quantify various hydrogen bonded species in amorphous solid dispersions as well as to serve as an experimental validation of MD simulations.

  7. Solid State NMR Study of Polystyrene Nanolatex Particles(I) 13C Spin-Lattice Relaxation Time

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    13C spin-lattice relaxtion times for polystyrene nanolatex particles have been investigated. It was found that the dramatic increase at 80℃ annealing temperature is well below the Tg temperature of bulk polystyrene, the increase of relaxation time of aromatic carbons is larger than that of for aliphatic carbons at transition annealing temperature.

  8. Local structure and molecular motions in imidazolium hydrogen malonate crystal as studied by {sup 2}H and {sup 13}C NMR

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, M., E-mail: mizuno@se.kanazawa-u.ac.jp; Chizuwa, M.; Umiyama, T.; Kumagai, Y.; Miyatou, T.; Ohashi, R.; Ida, T. [Kanazawa University, Kakuma, Department of Chemistry, Graduate School of Natural Science & Technology (Japan); Tansho, M.; Shimizu, T. [National Institute for Materials Science (Japan)

    2015-04-15

    The local structure and molecular motion of the imidazolium hydrogen malonate crystal were investigated using solid-state {sup 2}H and {sup 13}C NMR. The imidazolium ion undergoes isotropic rotation, which is correlated with a defect in the crystal, as observed by {sup 2}H NMR broadline spectra above 263 K. A 180{sup ∘} flip of the imidazolium ion in the regular site was observed from {sup 2}H NMR quadrupole Carr-Purcell-Meiboom-Gill (QCPMG) spectra. The Grotthuss mechanism was accompanied by a 180{sup ∘} flip of the imidazolium ion in regular sites. Moreover, the proton transfer associated with the imidazolium ion of the defective crystal is important for proton conductivity of the imidazolium hydrogen malonate crystal.

  9. General method of preparation of uniformly {sup 13}C, {sup 15}N-labeled DNA fragments for NMR analysis of DNA structures

    Energy Technology Data Exchange (ETDEWEB)

    Rene, Brigitte; Masliah, Gregoire; Zargarian, Loussine; Mauffret, Olivier; Fermandjian, Serge [UMR 8113 CNRS - LBPA Ecole Normale Superieure de Cachan, Institut Gustave Roussy, Departement de Biologie et Pharmacologie Structurales (France)], E-mail: sfermand@igr.fr

    2006-11-15

    Summary{sup 13}C, {sup 15}N labeling of biomolecules allows easier assignments of NMR resonances and provides a larger number of NMR parameters, which greatly improves the quality of DNA structures. However, there is no general DNA-labeling procedure, like those employed for proteins and RNAs. Here, we describe a general and widely applicable approach designed for preparation of isotopically labeled DNA fragments that can be used for NMR studies. The procedure is based on the PCR amplification of oligonucleotides in the presence of labeled deoxynucleotides triphosphates. It allows great flexibility thanks to insertion of a short DNA sequence (linker) between two repeats of DNA sequence to study. Size and sequence of the linker are designed as to create restriction sites at the junctions with DNA of interest. DNA duplex with desired sequence and size is released upon enzymatic digestion of the PCR product. The suitability of the procedure is validated through the preparation of two biological relevant DNA fragments.

  10. Cross polarization, magic-angle spinning /sup 13/C nuclear magnetic resonance spectroscopy of soil humic fractions

    Energy Technology Data Exchange (ETDEWEB)

    Saiz-Jimenez, C.; Hawkins, B.L.; Maciel, G.E.

    1986-01-01

    Cross polarization, magic-angle spinning /sup 13/C nuclear magnetic resonance spectroscopy was used to characterize humic fractions isolated from different soils. The humic acid fractions are more aromatic than the humin fractions, probably due to the higher polysaccharide content of humins. However, fulvic acid fractions are more aromatic than the corresponding humic acid and humin fractions. These results can be interpreted in terms of the isolation procedure, because the high affinity of Polyclar AT for phenols results in higher aromaticities as compared with other isolation methods (e.g. charcoal).

  11. Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

    Science.gov (United States)

    2016-01-01

    Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

  12. Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

    Science.gov (United States)

    2016-01-01

    Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil. PMID:27668136

  13. A study of the experimental and theoretical infrared, Raman, 1H and 13C NMR spectra of the biochemicals valeric and valproic acids

    Science.gov (United States)

    Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

    2014-10-01

    The structural stability, vibrational, 1H and 13C NMR spectra of valeric and valproic acids were investigated by the B3LYP calculations with the 6-311G** basis set. Valeric acid is predicted to exist predominantly in the planar cis form (80% abundance). Valproic acid is predicted to have an equilibrium mixture of 68% gauche-1 and 32% gauche-2 structures at 298.15 K. The spectral feature of the Osbnd H stretching mode in the infrared spectra of both acids suggests the presence of strong H-bonding in the condensed phase of valeric acid and weak H-bonding in the case of valproic acid. The harmonic and anharmonic vibrational wavenumbers were computed at the B3LYP level of theory and tentative vibrational assignments were provided on the basis of combined theoretical and experimental infrared and Raman data of the molecules. Not all of the calculated anharmonic wavenumbers showed a consistent trend with the observed wavenumbers. The 1H and 13C NMR spectra of both acids were interpreted by experimental and DFT calculated chemical shifts of the two acids. The RMSD between experimental and theoretical 1H and 13C chemical shifts for valeric acid is 1.8 and 3.8 ppm, whereas for valproic acid, it is 1.4 and 4.5 ppm, respectively.

  14. Multidimensional solid-state NMR studies of the structure and dynamics of pectic polysaccharides in uniformly 13C-labeled Arabidopsis primary cell walls

    Energy Technology Data Exchange (ETDEWEB)

    Dick-Perez, Marilu; Wang, Tuo; Salazar, Andre; Zabotina, Olga A.; Hong, Mei

    2012-07-08

    Plant cell wall (CW) polysaccharides are responsible for the mechanical strength and growth of plant cells; however, the high-resolution structure and dynamics of the CW polysaccharides are still poorly understood because of the insoluble nature of these molecules. Here, we use 2D and 3D magic-angle-spinning (MAS) solid-state NMR (SSNMR) to investigate the structural role of pectins in the plant CW. Intact and partially depectinated primary CWs of Arabidopsis thaliana were uniformly labeled with 13C and their NMR spectra were compared. Recent 13C resonance assignment of the major polysaccharides in Arabidopsis thaliana CWs allowed us to determine the effects of depectination on the intermolecular packing and dynamics of the remaining wall polysaccharides. 2D and 3D correlation spectra show the suppression of pectin signals, confirming partial pectin removal by chelating agents and sodium carbonate. Importantly, higher cross peaks are observed in 2D and 3D 13C spectra of the depectinated CW, suggesting higher rigidity and denser packing of the remaining wall polysaccharides compared with the intact CW. 13C spin–lattice relaxation times and 1H rotating-frame spin–lattice relaxation times indicate that the polysaccharides are more rigid on both the nanosecond and microsecond timescales in the depectinated CW. Taken together, these results indicate that pectic polysaccharides are highly dynamic and endow the polysaccharide network of the primary CW with mobility and flexibility, which may be important for pectin functions. This study demonstrates the capability of multidimensional SSNMR to determine the intermolecular interactions and dynamic structures of complex plant materials under near-native conditions. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Continuous Flow - Cavity RingDown Spectroscopy Using a Novel Universal Interface for High-Precision Bulk 13C Analysis

    Science.gov (United States)

    Saad, Nabil; Richman, Bruce

    2010-05-01

    We have developed the world's first optical spectroscopy-based system for bulk stable isotope analysis of 13C. The system is based on a novel universal interface, named LIAISON, capable of coupling to almost any CO2-generating sample preparation front-end ranging from an elemental analyzer to any dissolved carbon analysis module, which are of significant use in geochemical, ecological and food authentication studies. In one specific application, we have coupled LIAISON to an elemental analyzer (EA) and to a cavity ring-down spectrometer (CRDS) for 13C isotopic analysis of adulterated honey samples. Another application was developed to analyze dissolved inorganic carbon in water samples. LIAISON is suited for handling a high-throughput sample analysis process by running three different gas handling operations in parallel: Admitting combustion gas from the EA into a first gas bellows, analyzing the previous sample collected into a second gas bellows with CRDS, and flushing and purging a third gas bellows in preparation for the upcoming sample collection operation. The sample-to-sample analysis time is 10 minutes and the operation is completely automated for the whole front-end auto-sampler tray capacity, requiring no operator intervention. The CRDS data are collected, tabulated and saved into an output text file. The memory effect between the USGS L-Glutamic acid standard at natural abundance and the moderately enriched USGS L-Glutamic acid standard is excluded by the selection of the adequate number and duration of flush and purge cycles of the gas sample bags. The system's proven accuracy was cross-checked with EA-IRMS and its achieved precision was typically less than 0.2 permil, including the 13C-enriched tested samples. The LIAISON-CRDS system presented here provides a fully automated solution for 13C bulk stable isotope analysis with unprecedented ease-of-use and possible field portability and application with the availability of a compact front-end. In

  16. Experimental (FT-IR, FT-Raman, UV-Vis, 1H and 13C NMR) and computational (density functional theory) studies on 3-bromophenylboronic acid

    Science.gov (United States)

    Karabacak, M.; Kose, E.; Atac, A.; Sas, E. B.; Asiri, A. M.; Kurt, M.

    2014-11-01

    Structurally, boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent (i.e., C-Br bond) and two hydroxyl groups to fill the remaining valences on the boron atom. We studied 3-bromophenylboronic acid (3BrPBA); a derivative of boronic acid. This study includes the experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis) techniques and theoretical (DFT-density functional theory) calculations. The experimental data are recorded, FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase. 1H and 13C NMR spectra are recorded in DMSO solution. UV-Vis spectrum is recorded in the range of 200-400 nm for each solution (in ethanol and water). The theoretical calculations are computed DFT/B3LYP/6-311++G(d,p) basis set. The optimum geometry is also obtained from inside for possible four conformers using according to position of hydrogen atoms after the scan coordinate of these structures. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and parallel quantum solutions (PQS) program. 1H and 13C NMR chemical shifts are racked on by using the gauge-invariant atomic orbital (GIAO) method. The time-dependent density functional theory (TD-DFT) is used to find HOMO and LUMO energies, excitation energies, oscillator strengths. The density of state of the studied molecule is investigated as total and partial density of state (TDOS and PDOS) and overlap population density of state (OPDOS or COOP) diagrams have been presented. Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential surface (MEPs) and thermodynamic properties are performed. At the end of this work, the results are ensured beneficial for the literature contribution.

  17. The influence of heme ruffling on spin densities in ferricytochromes c probed by heme core 13C NMR

    OpenAIRE

    Kleingardner, Jesse G.; Bowman, Sarah E. J.; Bren, Kara L.

    2013-01-01

    The heme in cytochromes c undergoes a conserved out-of-plane distortion known as ruffling. For cytochromes c from the bacteria Hydrogenobacter thermophilus and Pseudomonas aeruginosa, NMR and EPR spectra have been shown to be sensitive to the extent of heme ruffling and to provide insights into the effect of ruffling on electronic structure. Using mutants of each of these cytochromes that differ in the amount of heme ruffling, NMR characterization of the low-spin (S=1/2) ferric proteins has c...

  18. Chemotaxonomy of three genera of the Annonaceae family using self-organizing maps and {sup 13}C NMR data of diterpenes

    Energy Technology Data Exchange (ETDEWEB)

    Scotti, Luciana; Tavares, Josean Fechine; Silva, Marcelo Sobral da [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Ciencias Farmaceuticas; Falcao, Emanuela Viana; Silva, Luana de Morais e; Soares, Gabriela Cristina da Silva; Scotti, Marcus Tullius, E-mail: mtscotti@ccae.ufpb.br [Universidade Federal da Paraiba (UFPB), Rio Tinto, PB (Brazil). Dept. de Engenharia e Meio Ambiente

    2012-07-01

    The Annonaceae family is distributed throughout Neotropical regions of the world. In Brazil, it covers nearly all natural formations particularly Annona, Xylopia and Polyalthia and is characterized chemically by the production of sources of terpenoids (mainly diterpenes), alkaloids, steroids, polyphenols and, flavonoids. Studies from {sup 13}C NMR data of diterpenes related with their botanical occurrence were used to generate self-organizing maps. Results corroborate those in the literature obtained from morphological and molecular data for three genera and the model can be used to project other diterpenes. Therefore, the model produced can predict which genera are likely to contain a compound. (author)

  19. STUDY ON THE SEQUENCE STRUCTURE OF BUTADIENE-STYRENE RUBBER BY 13C-NMR METHOD Ⅲ. QUANTITATIVE CHARACTERIZATION OF SEQUENCE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiaonong; HU Liping; YAN Baozhen; JIAO Shuke

    1990-01-01

    The quantitative description of the sequence structure of emulsion-processed SBR and solution-processed SBR (by lithium catalyst)was carried out based on their spectral data of 13C-NMR.The calculating formulae which could be used to obtain diad concentration from the peak intensities of carbon spectra, average block length, average number of block, and the microstructure composition of the molecular chain were derived. The quantitative result showed that on the molecular chain styrene unit had the tendency to attach to trans-1,4 butadiene unit. The calculated result of the microstructure was in good agreement with that obtained through IR measurement.

  20. A STUDY ON CONFORMATIONAL STRUCTURE OF MODEL COMPOUND OF NOVEL SIDE CHAIN LIQUID CRYSTALLINE POLYMER BY USING HIGH RESOLUTION SOLID STATE 13C-NMR

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaozhen; LU Qun; FENG Liwen; ZHU Shannong

    1993-01-01

    13C-NMR chemical shifts of model compound of a novel side chain liquid crystalline polymer,poly 2,5-bis (4-alkoxybenzoyloxy) styrene,have been assigned in this study.Moreover,by using high-resolution solid-state CP/MAS (cross polarization/magic angle spinning) technique,the spectrum shows that in the crystalline state the ester linkage has a conformation nearly perpendicular to the either side of ring planes,and that the alkoxy groups are not fully in zigzag form.The possible conformational changes around the mesogens from the solid state to the mesophase are discussed.

  1. 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.

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

    International Nuclear Information System (INIS)

    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

  3. Conformational distribution of baclofen analogues by 1H and 13C NMR analysis and ab initio HF MO STO-3G or STO-3G* calculations

    Science.gov (United States)

    Vaccher, Claude; Berthelot, Pascal; Debaert, Michel; Vermeersch, Gaston; Guyon, René; Pirard, Bernard; Vercauteren, Daniel P.; Dory, Magdalena; Evrard, Guy; Durant, François

    1993-12-01

    The conformations of 3-(substituted furan-2-yl) and 3-(substituted thien-2-yl)-γ-aminobutyric acid 1-9 in solution (D 2O) are estimated from high-resolution (300 MHz) 1H NMR coupling data. Conformations and populations of conformers are calculated by means of a modified Karplus-like relationship for the vicinal coupling constants. The results are compared with X-ray crystallographic investigations (torsion angles) and ab initio HF MO ST-3G or STO-3G* calculations. 1H NMR spectral analysis shows how 1-9 in solution retain the preferred g- conformation around the C3C4 bond, as found in the solid state, while a partial rotation is set up around the C2C3 bond: the conformations about C2C3 are all highly populated in solution. The 13C spin-lattice relaxation times are also discussed.

  4. Analysis of the mechanical properties and characterization by solid state {sup 13} C NMR of recycled EVA copolymer/silica composites

    Energy Technology Data Exchange (ETDEWEB)

    Stael, Giovanni Chaves [Observatorio Nacional, Rio de Janeiro, RJ (Brazil)]. E-mail: stael@on.br; Rocha, Marisa Cristina Guimaraes [Universidade do Estado do Rio de Janeiro, Nova Friburgo, RJ (Brazil). Instituto Politecnico; Menezes, Sonia Maria Cabral de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Quimica; D' Almeida, Jose Roberto Morais; Ruiz, Naira Machado da Silva [Pontificia Universidade Catolica do Rio de Janeiro, RJ (Brazil)

    2005-07-15

    The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate) - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM), and the {sup 13} C Nuclear Magnetic Resonance (NMR) showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group. (author)

  5. Methyl labeling and TROSY NMR spectroscopy of proteins expressed in the eukaryote Pichia pastoris

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Lindsay; Zahm, Jacob A.; Ali, Rustam [University of Texas Southwestern Medical Center, Department of Biophysics (United States); Kukula, Maciej; Bian, Liangqiao [University of Texas at Arlington, Shimadzu Center for Advanced Analytical Chemistry (United States); Patrie, Steven M. [University of Texas Southwestern Medical Center, Department of Pathology (United States); Gardner, Kevin H. [CUNY Advanced Science Research Center, Structural Biology Initiative (United States); Rosen, Michael K.; Rosenbaum, Daniel M., E-mail: dan.rosenbaum@utsouthwestern.edu [University of Texas Southwestern Medical Center, Department of Biophysics (United States)

    2015-07-15

    {sup 13}C Methyl TROSY NMR spectroscopy has emerged as a powerful method for studying the dynamics of large systems such as macromolecular assemblies and membrane proteins. Specific {sup 13}C labeling of aliphatic methyl groups and perdeuteration has been limited primarily to proteins expressed in E. coli, preventing studies of many eukaryotic proteins of physiological and biomedical significance. We demonstrate the feasibility of efficient {sup 13}C isoleucine δ1-methyl labeling in a deuterated background in an established eukaryotic expression host, Pichia pastoris, and show that this method can be used to label the eukaryotic protein actin, which cannot be expressed in bacteria. This approach will enable NMR studies of previously intractable targets.

  6. An introduction to biological NMR spectroscopy

    International Nuclear Information System (INIS)

    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)

  7. Complex Mixture Analysis of Organic Compounds in Yogurt by NMR Spectroscopy.

    Science.gov (United States)

    Lu, Yi; Hu, Fangyu; Miyakawa, Takuya; Tanokura, Masaru

    2016-01-01

    NMR measurements do not require separation and chemical modification of samples and therefore rapidly and directly provide non-targeted information on chemical components in complex mixtures. In this study, one-dimensional (¹H, (13)C, and (31)P) and two-dimensional (¹H-(13)C and ¹H-(31)P) NMR spectroscopy were conducted to analyze yogurt without any pretreatment. ¹H, (13)C, and (31)P NMR signals were assigned to 10 types of compounds. The signals of α/β-lactose and α/β-galactose were separately observed in the ¹H NMR spectra. In addition, the signals from the acyl chains of milk fats were also successfully identified but overlapped with many other signals. Quantitative difference spectra were obtained by subtracting the diffusion ordered spectroscopy (DOSY) spectra from the quantitative ¹H NMR spectra. This method allowed us to eliminate interference on the overlaps; therefore, the correct intensities of signals overlapped with those from the acyl chains of milk fat could be determined directly without separation. Moreover, the ¹H-(31)P HMBC spectra revealed for the first time that N-acetyl-d-glucosamine-1-phosphate is contained in yogurt. PMID:27322339

  8. Preparation of Uniformly 13C,15N-Labeled Recombinant Human Amylin for Solid-State NMR Investigation

    DEFF Research Database (Denmark)

    Kosicka, Iga; Kristensen, Torsten; Bjerring, Morten;

    2014-01-01

    A number of diseases are caused by the formation of amyloid fibrils. Detailed understanding of structural features of amyloid fibers is of great importance for our understanding of disease progression and design of agents for diagnostics or potential prevention of protein aggregation. In lack of ...... and electron microscopy, show toxicity towards human cells, and demonstrate that produced material may form the basis for structure determination using solid-state NMR....... crystal ordering, solid-state NMR forms the most suited method to determine the structures of the fibrils with atomic resolution. To exploit this potential, large amounts of isotopic-labeled protein need to be obtained through recombinant protein expression. However, expression and purification of...

  9. Amino-acid selective experiments on uniformly 13C and 15N labeled proteins by MAS NMR: Filtering of lysines and arginines

    Science.gov (United States)

    Jehle, Stefan; Rehbein, Kristina; Diehl, Anne; van Rossum, Barth-Jan

    2006-12-01

    Amino-acid selective magic-angle spinning (MAS) NMR experiments can aid the assignment of ambiguous cross-peaks in crowded spectra of solid proteins. In particular for larger proteins, data analysis can be hindered by severe resonance overlap. In such cases, filtering techniques may provide a good alternative to site-specific spin-labeling to obtain unambiguous assignments that can serve as starting points in the assignment procedure. In this paper we present a simple pulse sequence that allows selective excitation of arginine and lysine residues. To achieve this, we make use of a combination of specific cross-polarization for selective excitation [M. Baldus, A.T. Petkova, J. Herzfeld, R.G. Griffin, Cross polarization in the tilted frame: assignment and spectral simplification in heteronuclear spin systems, Mol. Phys. 95 (1998) 1197-1207.] and spin diffusion for transfer along the amino-acid side-chain. The selectivity of the filter is demonstrated with the excitation of lysine and arginine side-chain resonances in a uniformly 13C and 15N labeled protein preparation of the α-spectrin SH3 domain. It is shown that the filter can be applied as a building block in a 13C- 13C lysine-only correlation experiment.

  10. Spectroscopy and perturbation analysis of the A$^1\\Pi$(v=0) state of $^{13}$C$^{16}$O

    CERN Document Server

    Niu, M L; Trivikram, T Madhu; Heays, A N; de Oliveira, N; Salumbides, E J; Ubachs, and W

    2016-01-01

    The lowest $v=0$ level of the A$^1\\Pi$, state of the $^{13}$C$^{16}$O isotopologue of carbon monoxide has been reinvestigated with a variety of high resolution spectroscopic techniques. The A$^1\\Pi-$X$^1\\Sigma^+(0,0)$ band has been studied by vacuum-ultraviolet Fourier-transform absorption spectroscopy, using the SOLEIL synchrotron as a radiation source. Spectra were obtained under quasi-static gas conditions at liquid-nitrogen temperature, room temperature and at an elevated temperature of 900 K, with absolute accuracies of 0.01$-$0.03 cm$^{-1}$. Two-photon Doppler-free laser spectroscopy has been applied to a limited number of transitions in the A$^1\\Pi-$X$^1\\Sigma^+(0,0)$ band, under collision-free circumstances of a molecular beam, yielding an absolute accuracy of 0.002 cm$^{-1}$. The third technique is high-resolution Fourier-transform emission spectroscopy in the visible region applied to the B$^1\\Sigma^+-$A$^1\\Pi(0,0)$ band in a gas discharge, at an absolute accuracy of up to 0.003 cm$^{-1}$. With thes...

  11. Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

    DEFF Research Database (Denmark)

    Radula-Janik, Klaudia; Kupka, Teobald; Ejsmont, Krzysztof;

    2013-01-01

    ). The decreasing electronegativity of the halogen substituent (F, Cl, Br and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions....... The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit ZORA method. Significant heavy atom shielding effects for the carbon atom directly bonded with bromine and iodine were observed (~ -10 and ~ -30 ppm while the other carbon shifts were practically unaffected...

  12. NMR ({sup 1}H and {sup 13}C) based signatures of abnormal choline metabolism in oral squamous cell carcinoma with no prominent Warburg effect

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Swarnendu, E-mail: Swarna.bag@gmail.com [School of Medical Science and Technology, Indian Institute of Technology-Kharagpur, 721302 West Bengal (India); Banerjee, Deb Ranjan, E-mail: debranjan2@gmail.com [Department of Chemistry, Indian Institute of Technology-Kharagpur, 721302 West Bengal (India); Basak, Amit, E-mail: absk@chem.iitkgp.ernet.in [Department of Chemistry, Indian Institute of Technology-Kharagpur, 721302 West Bengal (India); Das, Amit Kumar, E-mail: amitk@hijli.iitkgp.ernet.in [Department of Biotechnology, Indian Institute of Technology-Kharagpur, 721302 West Bengal (India); Pal, Mousumi, E-mail: drmpal62@gmail.com [Department of Oral and Maxillofacial Pathology, Guru Nanak Institute of Dental Sciences and Research, Kolkata, West Bengal (India); Banerjee, Rita, E-mail: ritabanerjee@outlook.com [Department of Science and Technology, New Mehrauli Road, New Delhi 110016 (India); Paul, Ranjan Rashmi, E-mail: dr_rsspaul@yahoo.co.in [Department of Oral and Maxillofacial Pathology, Guru Nanak Institute of Dental Sciences and Research, Kolkata, West Bengal (India); Chatterjee, Jyotirmoy, E-mail: jchatterjee.iitkgp@gmail.com [School of Medical Science and Technology, Indian Institute of Technology-Kharagpur, 721302 West Bengal (India)

    2015-04-17

    At functional levels, besides genes and proteins, changes in metabolome profiles are instructive for a biological system in health and disease including malignancy. It is understood that metabolomic alterations in association with proteomic and transcriptomic aberrations are very fundamental to unravel malignant micro-ambient criticality and oral cancer is no exception. Hence deciphering intricate dimensions of oral cancer metabolism may be contributory both for integrated appreciation of its pathogenesis and to identify any critical but yet unexplored dimension of this malignancy with high mortality rate. Although several methods do exist, NMR provides higher analytical precision in identification of cancer metabolomic signature. Present study explored abnormal signatures in choline metabolism in oral squamous cell carcinoma (OSCC) using {sup 1}H and {sup 13}C NMR analysis of serum. It has demonstrated down-regulation of choline with concomitant up-regulation of its break-down product in the form of trimethylamine N-oxide in OSCC compared to normal counterpart. Further, no significant change in lactate profile in OSCC possibly indicated that well-known Warburg effect was not a prominent phenomenon in such malignancy. Amongst other important metabolites, malonate has shown up-regulation but D-glucose, saturated fatty acids, acetate and threonine did not show any significant change. Analyzing these metabolomic findings present study proposed trimethyl amine N-oxide and malonate as important metabolic signature for oral cancer with no prominent Warburg effect. - Highlights: • NMR ({sup 1}H and {sup 13}C) study of Oral Squamous cell Carcinoma Serum. • Abnormal Choline metabolomic signatures. • Up-regulation of Trimethylamine N-oxide. • Unchanged lactate profile indicates no prominent Warburg effect. • Proposed alternative glucose metabolism path through up-regulation of malonate.

  13. Theoretical study on the influence of different para-substituents on 13C NMR of the single carbonyl curcumin analogues

    Science.gov (United States)

    Jia, Fei-yun; Ran, Ming; Zhang, Bo

    2015-12-01

    The structure of eight kinds of different para-substituents curcumin analogues has been optimized at the level of B3LYP/6-31G( d, p), under which the stability has been verified by means of vibration analysis. Moreover, NMR spectra of curcumin analogues compounds have been studied at the level of B3LYP/6-311G( d, p) by GIAO method. The results show that the structure of eight compounds, a larger conjugated system, has good planarity. The effect of ortho-substituents on bond lengths and bond angles is greater than para and meta. Different substituents and different positions of substituents all have different influence on NMR of the single carbonyl curcumin analogues. In general, after the hydrogen atom on the benzene ring is substituted by other groups, the δ value of α-C changes significantly, the δ value of ortho-carbon atom may also have great change, but the δ value change of meta-carbon atoms is not too obvious. The effect of substituent electronegativity on α-C atoms presents obvious regularity, while the influence of conjugate effect on carbon atoms of benzene ring is more complex. Finally, the bigger substituted alkyl is, the more the δ value of α-C increases.

  14. Quantitative analysis on CO2 absorption and desorption in monoethanolamine (MEA) solution by using 13C NMR%13C NMR定量分析一乙醇胺(MEA)与CO2的吸收和解吸特性

    Institute of Scientific and Technical Information of China (English)

    郭超; 陈绍云; 陈思铭; 张永春

    2014-01-01

    13C NMR是一种有效的测定有机胺与CO2反应过程中离子浓度变化的检测手段。本文采用13C NMR分析了一乙醇胺(MEA)吸收与解吸CO2过程,吸收与解吸实验温度分别在313K和393K下进行。结果表明,吸收CO2过程中生成了MEA氨基甲酸盐、质子胺MEAH+与HCO3-/CO32-,并且CO2与MEA反应时先生成MEA氨基甲酸盐,当溶液吸收的CO2担载量达到0.455molCO2/mol 胺时,才产生HCO3-/CO32-离子。在MEA吸收CO2过程中,MEA氨基甲酸盐的摩尔分数先增加后减少。在解吸过程中,MEA氨基甲酸盐的摩尔分数同样先增加后减少。HCO3-/CO32-在解吸过程中很容易就能被解吸,而生成的MEA氨基甲酸盐中大约有75%在解吸过程中并没有被解吸。%13C NMR spectroscopy is a suitable analytical method to get quantitative information on the species distribution in aqueous amine solutions loaded with carbon dioxide (CO2). 13C NMR is used for quantitative analysis on CO2 absorption and desorption in monoethanolamine (MEA) solution. Temperatures of absorption and desorption experiments are 313K and 393K,respectively. From 13C NMR spectroscopy,it is found that the main MEA species under the absorption conditions studied are free amine,protonated amine,MEA carbamate,and HCO3-/CO32-. At absorption step,MEA carbamate is produced first,when CO2 loading is getting higher to 0.455mol CO2/mol amine in this experiment,HCO3-/CO32- appears. The mole fraction of the MEA carbamate increases first with absorption time,reaches their maximum,and then decreases. The mole fraction of HCO3-/CO32-consistently increases with the increase of absorption time. At the desorption step,the mole fraction of MEA carbamate increases at early stage,reaches a maximum,and then decreases up to the end. After the desorption process,all HCO3-/CO32-can be stripped while about 75%of MEA carbamate still exist in the MEA solution.

  15. Solid-state and solution /sup 13/C NMR in the conformational analysis of methadone-hydrochloride and related narcotic analgesics

    Energy Technology Data Exchange (ETDEWEB)

    Sumner, S.C.J.

    1986-01-01

    Solid state and solution /sup 13/C NMR have been used to study the conformations of the racemic mixtures and single enantiomers of methadone hydrochloride, alpha and beta methadol hydrochloride, and alpha and beta acetylmethadol hydrochloride. The NMR spectra acquired for the compounds as solids, and in polar and nonpolar solvents are compared, in order to determine the conformation of the molecules in solution. To determine the reliability of assigning solution conformations by comparing solution and solid state chemical shift data, three bond coupling constants measured in solution are compared with those calculated from X-ray data. The conformations of the racemic mixture and plus enantiomer of methadone hydrochloride have been shown to be very similar in the solid state, where minor differences in conformation can be seen by comparing NMR spectra obtained for the solids. Also shown is that the molecules of methadone hydrochloride have conformations in polar and in nonpolar solvents which are very similar to the conformation of the molecules in the solid state.

  16. Application of Spectroscopic Techniques (FT-IR, 13C NMR) to the analysis of humic substances in volcanic soils along an environmental gradient (Tenerife, Canary Islands, Spain)

    Science.gov (United States)

    Rodriguez Rodriguez, Antonio; María Armas Herrera, Cecilia; González Pérez, José Antonio; González-Vila, Francisco Javier; Arbelo Rodríguez, Carmen Dolores; Mora Hernández, Juan Luis; Polvillo Polo, Oliva

    2010-05-01

    Andosols and andic soils are considered as efficient C-sinks in terms of C sequestration. These soils are usually developed from volcanic materials, and are characterized by a predominance of short-range ordered minerals like allophanes, imogolite and other Fe and Al oxyhydroxides. Such materials occur commonly associated with organic compounds, thus generating highly stable organo-mineral complexes and leading to the accumulation of a high amount of organic carbon. Spectroscopic methods like FT-IR and 13C NMR are suitable for the analysis of the chemical structure of soil humic substances, and allow identifying distinct functional groups and protein, lipids, lignin, carbohydrate-derived fragments. In this work we study the structural features of four soils developed on Pleistocene basaltic lavae in Tenerife (Canary Island, Spain), distributed along an altitudinal climatic gradient. The soil sequence comprises soils with different degree of geochemical evolution and andic character, including a mineral ‘Hypersalic Solonchak' (Tabaibal de Rasca), a slightly vitric ‘Luvic Phaeozem' (Los Frailes), a degraded and shallow ‘Endoleptic, fulvic, silandic Andosol' (Siete Lomas), and a well-developed and deep ‘Fulvic, silandic, Andosol' (Ravelo). Samples of the raw soil and humic and fulvic acids isolated from the surface horizons were analyzed. The results show a low content of organic carbon in the mineral soil, the inherited humin predominating, and a very high content of humic and fulvic acids in Andosols. The FT-IR and 13C NMR spectra of the raw soil samples show a low resolution, related to interferences from mineral complexes signals, particularly in soils with lower organic carbon content. 13C NMR shows a predominance of O-alkyl carbon (derived of carbohydrates) in andic soils, whereas O-alkyl and aromatic fractions are most evident in the mineral soil. The humic acids spectra are characterized by a dominance of alkyl and aromatic fractions with a high degree

  17. Chemical structures of coal lithotypes before and after CO2 adsorption as investigated by advanced solid-state 13C nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Cao, X.; Mastalerz, Maria; Chappell, M.A.; Miller, L.F.; Li, Y.; Mao, J.

    2011-01-01

    Four lithotypes (vitrain, bright clarain, clarain, and fusain) of a high volatile bituminous Springfield Coal from the Illinois Basin were characterized using advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. The NMR techniques included quantitative direct polarization/magic angle spinning (DP/MAS), cross polarization/total sideband suppression (CP/TOSS), dipolar dephasing, CHn selection, and recoupled C-H long-range dipolar dephasing techniques. The lithotypes that experienced high-pressure CO2 adsorption isotherm analysis were also analyzed to determine possible changes in coal structure as a result of CO2 saturation at high pressure and subsequent evacuation. The main carbon functionalities present in original vitrain, bright clarain, clarain and fusain were aromatic carbons (65.9%-86.1%), nonpolar alkyl groups (9.0%-28.9%), and aromatic C-O carbons (4.1%-9.5%). Among these lithotypes, aromaticity increased in the order of clarain, bright clarain, vitrain, and fusain, whereas the fraction of alkyl carbons decreased in the same order. Fusain was distinct from other three lithotypes in respect to its highest aromatic composition (86.1%) and remarkably small fraction of alkyl carbons (11.0%). The aromatic cluster size in fusain was larger than that in bright clarain. The lithotypes studied responded differently to high pressure CO2 saturation. After exposure to high pressure CO2, vitrain and fusain showed a decrease in aromaticity but an increase in the fraction of alkyl carbons, whereas bright clarain and clarain displayed an increase in aromaticity but a decrease in the fraction of alkyl carbons. Aromatic fused-rings were larger for bright clarain but smaller for fusain in the post-CO2 adsorption samples compared to the original lithotypes. These observations suggested chemical CO2-coal interactions at high pressure and the selectivity of lithotypes in response to CO2 adsorption. ?? 2011 Elsevier B.V.

  18. Solid-State (13)C NMR Delineates the Architectural Design of Biopolymers in Native and Genetically Altered Tomato Fruit Cuticles.

    Science.gov (United States)

    Chatterjee, Subhasish; Matas, Antonio J; Isaacson, Tal; Kehlet, Cindie; Rose, Jocelyn K C; Stark, Ruth E

    2016-01-11

    Plant cuticles on outer fruit and leaf surfaces are natural macromolecular composites of waxes and polyesters that ensure mechanical integrity and mitigate environmental challenges. They also provide renewable raw materials for cosmetics, packaging, and coatings. To delineate the structural framework and flexibility underlying the versatile functions of cutin biopolymers associated with polysaccharide-rich cell-wall matrices, solid-state NMR spectra and spin relaxation times were measured in a tomato fruit model system, including different developmental stages and surface phenotypes. The hydrophilic-hydrophobic balance of the cutin ensures compatibility with the underlying polysaccharide cell walls; the hydroxy fatty acid structures of outer epidermal cutin also support deposition of hydrophobic waxes and aromatic moieties while promoting the formation of cell-wall cross-links that rigidify and strengthen the cuticle composite during fruit development. Fruit cutin-deficient tomato mutants with compromised microbial resistance exhibit less efficient local and collective biopolymer motions, stiffening their cuticular surfaces and increasing their susceptibility to fracture. PMID:26652188

  19. Solid-State (13)C NMR Delineates the Architectural Design of Biopolymers in Native and Genetically Altered Tomato Fruit Cuticles.

    Science.gov (United States)

    Chatterjee, Subhasish; Matas, Antonio J; Isaacson, Tal; Kehlet, Cindie; Rose, Jocelyn K C; Stark, Ruth E

    2016-01-11

    Plant cuticles on outer fruit and leaf surfaces are natural macromolecular composites of waxes and polyesters that ensure mechanical integrity and mitigate environmental challenges. They also provide renewable raw materials for cosmetics, packaging, and coatings. To delineate the structural framework and flexibility underlying the versatile functions of cutin biopolymers associated with polysaccharide-rich cell-wall matrices, solid-state NMR spectra and spin relaxation times were measured in a tomato fruit model system, including different developmental stages and surface phenotypes. The hydrophilic-hydrophobic balance of the cutin ensures compatibility with the underlying polysaccharide cell walls; the hydroxy fatty acid structures of outer epidermal cutin also support deposition of hydrophobic waxes and aromatic moieties while promoting the formation of cell-wall cross-links that rigidify and strengthen the cuticle composite during fruit development. Fruit cutin-deficient tomato mutants with compromised microbial resistance exhibit less efficient local and collective biopolymer motions, stiffening their cuticular surfaces and increasing their susceptibility to fracture.

  20. Quantification of xylooligomers in hot water wood extract by 1H-13C heteronuclear single quantum coherence NMR.

    Science.gov (United States)

    Yan, Jipeng; Kiemle, David; Liu, Shijie

    2015-03-01

    A new method that employs 2D-HSQCNMRwasdeveloped to determine xylooligomer concentrations in the hot water extracts of Paulownia elongata, aspen, sugar maple, southern hardwood mixture, and willow woodchips. Equations for computing oligomer concentrations calculation were developed based on HSQC corresponding resonance integrals of xylooligomer C1H1 and monomeric sugar standard curves. The degree of polymerization (DP) of xylooligomers in the hot water extract was computed by equation obtained from a series of xylooligomer standard solutions with DPs that ranged from 2 to 6. Another group of hot water wood extract that is served as a control group was hydrolyzed by 4% sulfuric acid at 121 °C for 60 min in order to convert all xylooligomer into xylose. As 2D-HSQC resonance response is different for acetylated xylo-units, as compared with non-acetylated units, proton NMR was used to calibrate the acetylated xylooligomer concentration. Xylooligomer concentrations determined from HSQC compared fairly well with data after hydrolysis. PMID:25498715

  1. Possibilities and limitations of sup 1 H and sup 13 C nuclear magnetic resonance spectroscopy for the identification and the quantitative determination of some naturally occurring carcinogenic risk factors. [Senecio vulgaris; Senecio vernalis; Senecio jacobaea; Euphorbia ingens

    Energy Technology Data Exchange (ETDEWEB)

    Pieters, L.

    1988-01-01

    The aim of this work was to develop a phytochemical screening method for some selected carcinogenic or tumor-promoting principles in higher plants. The pyrrolizidine alkaloids from some Senecio species (Compositae or Asteraceae), and the diterpene ester from Croton tiglium L. and Euphorbia ingens E. Mey (Euphorbiaceae) were chosen as representatives of both groups. The possibilities and limitations of {sup 1}H and {sup 13}C nuclear magnetic resonance spectroscopy ({sup 1}H and {sup 13}C NMR) for the analysis of mixtures of carcinogenic pyrrolizidine alkaloids were compared with high performance liquid chromatography, and gas chromatography with high performance liquid chromatography, and gas chromatography was well as gas chromatography - mass spectrometry. Senecio vulgaris L., Senecio vernalis Waldst. and Kit. and Senecio jacobaea L. were investigated.

  2. Use of 13C NMR and ftir for elucidation of degradation pathways during natural litter decomposition and composting I. early stage leaf degradation

    Science.gov (United States)

    Wershaw, R. L.; Leenheer, J.A.; Kennedy, K.R.; Noyes, T.I.

    1996-01-01

    Oxidative degradation of plant tissue leads to the formation of natural dissolved organic carbon (DOC) and humus. Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectrometry have been used to elucidate the chemical reactions of the early stages of degradation that give rise to DOC derived from litter and compost. The results of this study indicate that oxidation of the lignin components of plant tissue follows the sequence of O-demethylation, and hydroxylation followed by ring-fission, chain-shortening, and oxidative removal of substituents. Oxidative ring-fission leads to the formation of carboxylic acid groups on the cleaved ends of the rings and, in the process, transforms phenolic groups into aliphatic alcoholic groups. The carbohydrate components are broken down into aliphatic hydroxy acids and aliphatic alcohols.

  3. Characterization of high boiling fossil fuel distillates via /sup 1/H and /sup 13/C NMR analysis. Quarterly report IV, April 1--June 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Barlin, K.D.; O' Donnel, D.J.; Sigle, S.

    1979-01-01

    The completion of the /sup 13/C NMR analysis of the Wilmington polyaromatic-polar fractions 210-76 No. 16, 21 and 26 and the Gach Saran polyaromatic-polar fractions 208-76 No. 15, 20 and 25 completed the investigation of samples submitted under the original contract. The analysis of several additional samples in these series proved helpful in assessing the consistency of the measuring techniques and also permitted a more accurate determination of trends observed within a particular series. Included in these extra samples were Gach Saran polyaromatic-polar fractions No. 23 and 26. The analysis of these two samples were deemed appropriate when it was observed that the last fraction of the Gach Saran and Wilmington PAP series deviated from trends in Ar-C/Al-C observed in every other series investigated to date. The outcome of this investigation of additional fractions is discussed.

  4. Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies.

    Science.gov (United States)

    Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2015-03-01

    Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively (13)C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved.

  5. Use of 13C NMR and FTIR for elucidation of degradation pathways during natural litter decomposition and composting. I. Early stage leaf degradation

    International Nuclear Information System (INIS)

    Oxidative degradation of plant tissue leads to the formation of natural dissolved organic carbon (DOC) and humus. Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectrometry have been used to elucidate the chemical reactions of the early stages of degradation that give rise to DOC derived from litter and compost. The results of this study indicate that oxidation of the lignin components of plant tissue follows the sequence of O-demethylation, and hydroxylation followed by ring-fission, chain-shortening, and oxidative removal of substituents. Oxidative ring-fission leads to the formation of carboxylic acid groups on the cleaved ends of the rings and, in the process, transforms phenolic groups into aliphatic alcoholic groups. The carbohydrate components are broken down into aliphatic hydroxy acids and aliphatic alcohols. (author)

  6. New organic single crystal of (benzylthio)acetic acid: Synthesis, crystal structure, spectroscopic (ATR-FTIR, 1H and 13C NMR) and thermal characterization

    Science.gov (United States)

    Sienkiewicz-Gromiuk, Justyna; Tarasiuk, Bogdan; Mazur, Liliana

    2016-04-01

    (Benzylthio)acetic acid (Hbta) was synthesized with 78% yield from benzyl chloride and thiourea as substrates. Well-shaped crystals of Hbta were grown by slow solvent evaporation technique from pure methanol. The compound was investigated by single-crystal X-ray and powder diffraction techniques and was also characterized by other analytical methods, like ATR-FTIR, 1H and 13C NMR and TG/DSC. The acid molecule adopts bent conformation in the solid state. The crystal structure of Hbta is stabilized by numerous intermolecular interactions, including O-H···O, C-H···O, C-H···S and C-H···π contacts. Thermal decomposition of the obtained material takes place above 150 °C.

  7. Comparison among Different Gilthead Sea Bream (Sparus aurata Farming Systems: Activity of Intestinal and Hepatic Enzymes and 13C-NMR Analysis of Lipids

    Directory of Open Access Journals (Sweden)

    Vincenzo Zonno

    2009-12-01

    Full Text Available In order to evaluate differences in general health and nutritional values of gilthead sea bream (Sparus aurata, the effects of semi-intensive, land-based tanks and sea-cages intensive rearing systems were investigated, and results compared with captured wild fish. The physiological state was determined by measuring the activity of three different intestinal digestive enzymes: alkaline phosphatase (ALP, leucine aminopeptidase (LAP and maltase; and the activity of the hepatic ALP. Also, the hepatic content in protein, cholesterol, and lipid were assessed. 13C-NMR analysis for qualitative and quantitative characterization of the lipid fraction extracted from fish muscles for semiintensive and land based tanks intensive systems was performed. The lipid fraction composition showed small but significant differences in the monounsaturated/saturated fatty acid ratio, with the semi-intensive characterized by higher monounsaturated and lower saturated fatty acid content with respect to land based tanks intensive rearing system.

  8. Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies

    Science.gov (United States)

    Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2015-03-01

    Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively 13C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved.

  9. Primidone - An antiepileptic drug - characterisation by quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR and UV-Visible) investigations

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Subramanian, S.; Mohan, S.

    2013-05-01

    The solid phase FTIR and FT-Raman spectra of primidone were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The vibrational spectra were analysed and the observed fundamentals were assigned and analysed. The experimental wavenumbers were compared with the theoretical scaled vibrational wavenumbers determined by DFT methods. The Raman intensities were also determined with B3LYP/6-31G(d,p) method. The total electron density and molecular electrostatic potential surface of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The HOMO and LUMO energies were measured. Natural bond orbital analysis of primidone has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR spectra were recorded and the chemical shifts of the molecule were calculated.

  10. NMR studies of (U- sup 13 C)cyclosporin A bound to cyclophilin: Bound conformation and protions of cyclosporin involved in binding

    Energy Technology Data Exchange (ETDEWEB)

    Fesik, S.W.; Gampe, R.T. Jr.; Eaton, H.L.; Gemmecker, G.; Olejniczak, E.T.; Neri, P.; Holzman, T.F.; Egan, D.A.; Edalji, R.; Simmer, R.; Helfrich, R.; Hochlowski, J.; Jackson, M. (Abbott Labs., Abbott Park, IL (United States))

    1991-07-02

    Cyclosporin A (CsA), a potent immunosuppressant, is known to bind with high specificity to cyclophilin (CyP), a 17.7 kDa protein with peptidyl-prolyl isomerase activity. In order to investigate the three-dimensional structure of the CsA/CyP complex, the authors have applied a variety of multidimensional NMR methods in the study of uniformly {sup 13}C-labeled CsA bound to cyclophilin. The {sup 1}H and {sup 13}C NMR signals of cyclosporin A in the bound state have been assigned, and, from a quantitative interpretation of the 3D NOE data, the bound conformation of CsA has been determined. Three-dimensional structures of CsA calculated from the NOE data by using a distance geometry/simulated annealing protocol were found to be very different form previously determined crystalline and solution conformations of uncomplexed CsA. In addition, from CsA/CyP NOEs, the portions of CsA that interact with cyclophilin were identified. For the most part, those CsA residues with NOEs to cyclophilin were the same residues important for cyclophilin binding and immunosuppressive activity as determined from sturcture/activity relationships. The structural information derived in this study together with the known structure/activity relationships for CsA analogues may prove useful in the design of improved immunosuppressants. Moreover, the approach that is described for obtaining the structural information is widely applicable to the study of small molecule/large molecule interactions.

  11. Microscopic structural analysis of fractured silk fibers from Bombyx mori and Samia cynthia ricini using 13C CP/MAS NMR with a 1 mm microcoil MAS NMR probehead

    KAUST Repository

    Yamauchi, Kazuo

    2010-07-01

    Conformational changes have been studied in silk fibers from the domestic silkworm Bombyx mori and a wild silkworm Samia cynthia ricini as a result of fractured by stretching. About 300 samples consisting of only the fractured regions of [1-13C]Ala or [1-13C]Gly labeled silk fibers were collected and observed by 13C CP/MAS NMR spectra. The total amount of these fractured fibers is only about 1 mg and therefore we used a home-built 1 mm microcoil MAS NMR probehead. A very small increase in the fraction of random coil was noted for the alanine regions of both silk fibroins and for the glycine region of B. mori silk fibroin. However, there is no difference in the spectra before and after fractured for the glycine region of S. c. ricini silk fibroin. Thus, the influence of fracture occurs exclusively at the Ala region for S. c. ricini. The relationship between sequence, fracture and structure is discussed. © 2010 Elsevier Inc. All rights reserved.

  12. Application of 13C NMR to investigate the transformations and biodegradation of organic materials by wood- and soil-feeding termites, and a coprophagous litter-dwelling dipteran larva.

    Science.gov (United States)

    Hopkins, D W; Chudek, J A; Bignell, D E; Frouz, J; Webster, E A; Lawson, T

    1998-01-01

    Solid-state 13C nuclear magnetic resonance spectroscopy has been used to characterize the C in samples of the food (wood), gut contents and faeces from the wood-feeding termite, Microcerotermes parvus; soil in the guts and mound material from the soil-feeding termite, Thoracotermes macrothorax; and the food and faeces from the litter-feeding, coprophagous larvae of the dipteran fly, Bibio marci. Spectra from the wood-feeding termite indicated preferential loss of polysaccharide and accumulation of lignin with some modification to the O-aromatic-C and methoxyl-C (O-methyl-C) components during passage through the gut. Spectra for the soil-feeding termite indicated little change in the distribution of 13C between resonances following passage through the gut, except for some evidence of preferential polysaccharide loss. Interpretation of the spectra from these organisms was restricted by the relatively low C content of the soils and mound material, and by the large contribution to the NMR spectra from the gut tissue rather than the gut contents. Spectra for the litter-feeding dipteran larvae indicated preferential feeding on the polysaccharide-rich component of the litter and then overall loss of polysaccharide-C and accumulation of both aromatic-C and methoxyl-C in the gut. These changes were greater for the second passage than for the first passage through the gut, suggesting that principally mechanical and physical changes occurred initially and that chemical digestion was prevalent during the second passage.

  13. Using 13C-labeled benzene and Raman gas spectroscopy to investigate respiration and biodegradation kinetics following soil contamination

    Science.gov (United States)

    Jochum, Tobias; Popp, Juergen; Frosch, Torsten

    2016-04-01

    Soil and groundwater contamination with benzene can cause serious environmental damages. However, many soil microorganisms are capable to adapt and known to strongly control the fate of organic contamination. Cavity enhanced Raman gas spectroscopy (CERS) was applied to investigate the short-term response of indigenous soil bacteria to a sudden surface contamination with benzene regarding the temporal variations of gas products and their exchange rates with the adjacent atmosphere. 13C-labeled benzene was spiked on a silty-loamy soil column (sampled from Hainich National Park, Germany) in order to track and separate the changes in heterotrophic soil respiration - involving 12CO2 and O2 - from the microbial process of benzene degradation, which ultimately forms 13CO2.1 The respiratory quotient (RQ) of 0.98 decreased significantly after the spiking and increased again within 33 hours to a value of 0.72. This coincided with maximum 13CO2 concentration rates (0.63 μ mol m-2 s-1), indicating highest benzene degradation at 33 hours after the spiking event. The diffusion of benzene in the headspace and the biodegradation into 13CO2 were simultaneously monitored and 12 days after the benzene spiking no measurable degradation was detected anymore.1 The RQ finally returned to a value of 0.96 demonstrating the reestablished aerobic respiration. In summary, this study shows the potential of combining Raman gas spectroscopy and stable isotopes to follow soil microbial biodegradation dynamics while simultaneously monitoring the underlying respiration behavior. Support by the Collaborative Research Center 1076 Aqua Diva is kindly acknowledged. We thank Beate Michalzik for soil analysis and discussion. 1. T. Jochum, B. Michalzik, A. Bachmann, J. Popp and T. Frosch, Analyst, 2015, 140, 3143-3149.

  14. Crystal structure and theoretical study of IR and 1H and 13C NMR spectra of cordatin, a natural product with antiulcerogenic activity

    Science.gov (United States)

    Brasil, Davi S. B.; Alves, Cláudio N.; Guilhon, Giselle M. S. P.; Muller, Adolfo H.; Secco, Ricardo De S.; Peris, Gabriel; Llusar, Rosa

    Cordatin is a furan diterpenoid with a clerodane skeleton isolated from Croton palanostigma Klotzsch (Euphorbiaceae). This natural product shows significant antiulcerogenic activity, similar to cimetidine (Tagamet®), a compound used for the treatment of peptic ulcers. The crystal structure of cordatin was obtained by X-ray diffraction and its geometrical parameters were compared with theoretical calculations at the B3LYP theory level. The IR and NMR (1H and 13C chemical shifts and coupling constants) spectra were obtained and compared with the theoretical calculations. The B3LYP theory level, with the 6-31G(d,p) and 6-311G(d,p) basis set, provided IR absorption values close to the experimental data. Moreover, theoretical NMR parameters obtained in both gas phase and chloroform solvent at the B3PW91/DGDZVP, B3LYP/6-311+G(2d,p), and B3PW91/6-311+G(2d,p) levels showed good correlations with the experimental results.

  15. Anéis aromáticos condensados e relação E4/E6: estudo de ácidos húmicos de gleissolos por RMN de 13C no estado sólido utilizando a técnica CP/MAS desacoplamento defasado Condensed aromatic rings and E4/E6 ratio: humic acids in gleysoils studied by NMR CP/MAS13C, and dipolar dephasing

    Directory of Open Access Journals (Sweden)

    Sérgio da Costa Saab

    2007-04-01

    Full Text Available In this work, seven samples of humic acids extracted from gleysoils were investigated. These studies, using NMR CP/MAS 13C techniques, did not show significant correlation between the E4/E6 ratio and the degree of aromaticity. However, dipolar dephasing (DD measurements of condensed aromatic or substituted carbons showed a negative correlation of 0.94. Also, there was a good correlation between the amount of semiquinone free radicals measured by the EPR technique and condensed aromatic rings measured by NMR CP/MAS 13C with the DD technique. The content of semiquinone free radicals was quantified by EPR spectroscopy and was correlated with the humification (degree of aromaticity of the humic substances. The results indicated that the E4/E6 ratio identifies the degree of aromatic rings condensation. It was also found that the degree of aromaticity, measured by NMR, as frequently presented in the literature (by conventional CP/MAS, underestimates aromatic rings in condensed structures.

  16. Carbon-deuterium rotational-echo double-resonance NMR spectroscopy of lyophilized aspartame formulations.

    Science.gov (United States)

    Luthra, Suman A; Utz, Marcel; Gorman, Eric M; Pikal, Michael J; Munson, Eric J; Lubach, Joseph W

    2012-01-01

    In this study, changes in the local conformation of aspartame were observed in annealed lyophilized glasses by monitoring changes in the distance between two labeled sites using C-(2)H rotational-echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. Confirmation that the REDOR experiments were producing accurate distance measurement was ensured by measuring the (13)C-(15)N distance in glycine. The experiment was further verified by measuring the REDOR dephasing curve on (13)C-(2)H methionine. (13)C-(2)H REDOR dephasing curves were then measured on lyophilized aspartame-disaccharide formulations. In aspartame-sucrose formulation, the internuclear distances increased upon annealing, which correlated with decreased chemical reactivity. By contrast, annealing had only a minimal effect on the dephasing curve in aspartame-trehalose formulation. The results show that stability is a function of both mobility and local structure (conformation), even in a small molecule system such as lyophilized aspartame-sucrose.

  17. Analysis of human urine metabolites using SPE and NMR spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nuclear magnetic resonance (NMR) spectroscopic analysis of metabonome/metabolome has widespread applications in biomedical science researches. However, most of NMR resonances for urinary metabolites remain to be fully assigned. In the present study, human urine samples from two healthy volunteers were pre-treated with C18 solid-phase extraction and the resultant 5 sub-fractions were subjected to one- and two-dimensional NMR studies, including 1H J-Resolved, 1H-1H COSY, 1H-1H TOCSY, 1H-13C HSQC, and HMBC 2D NMR. More than 70 low molecular weight metabolites were identified, and complete assignments of 1H and 13C resonances including many complex coupled spin systems were obtained.

  18. Structural studies of PCU-hydrazones: NMR spectroscopy, X-ray diffractions, and DFT calculations

    Science.gov (United States)

    Veljković, Jelena; Šekutor, Marina; Molčanov, Krešimir; Lo, Rabindranath; Ganguly, Bishwajit; Mlinarić-Majerski, Kata

    2011-06-01

    In this article we present a detailed structural investigation for the configurational isomers of PCU-hydrazones. The structural characterization of these hydrazones was performed using NMR spectroscopy, X-ray diffraction analysis and theoretical calculations. The single crystal X-ray structures of PCU-hydrazones 6B and 6C have been solved and used to conclusively confirm the characterization obtained via NMR spectra of a particular isomer. Nuclear magnetic shielding values calculated for 6A-C using DFT calculations were correlated with the experimentally determined chemical shifts. The computed results were found to be in good agreement with the observed 13C NMR values. The computed NMR results helped to ascertain the isomers of PCU-hydrazones 4A-C.

  19. Rapid characterization of molecular diffusion by NMR spectroscopy.

    Science.gov (United States)

    Pudakalakatti, Shivanand M; Chandra, Kousik; Thirupathi, Ravula; Atreya, Hanudatta S

    2014-11-24

    An NMR-based approach for rapid characterization of translational diffusion of molecules has been developed. Unlike the conventional method of acquiring a series of 2D (13)C and (1)H spectra, the proposed approach involves a single 2D NMR spectrum, which can be acquired in minutes. Using this method, it was possible to detect the presence of intermediate oligomeric species of diphenylalanine in solution during the process of its self-assembly to form nanotubular structures. PMID:25331210

  20. In vivo NMR spectroscopy of ripening avocado

    International Nuclear Information System (INIS)

    Ripening of avocado fruit is associated with a dramatic increase in respiration. Previous studies have indicated that the increase in respiration is brought about by activation of the glycolytic reaction catalyzing the conversion of fructose-6-phosphate to fructose 1,6-bisphosphate. The authors reinvestigated the proposed role of glycolytic regulation in the respiratory increase using in vivo 31P nuclear magnetic resonance (NMR) spectroscopy using an external surface coil and analysis of phosphofructokinase (PFK), phosphofructophosphotransferase (PFP), and fructose 2,6-bisphosphate (fru 2,6-P2) levels in ripening avocado fruit. In vivo 31P NMR spectroscopy revealed large increases in ATP levels accompanying the increase in respiration. Both glycolytic enzymes, PFK and PFP, were present in avocado fruit, with the latter activity being highly stimulated by fru 2,6-P2. Fructose 2,6-bisphosphate levels increased approximately 90% at the onset of ripening, indicating that the respiratory increase in ripening avocado may be regulated by the activation of PFP brought about by an increase in fru 2,6-P2

  1. /sup 14/C isotope effects in /sup 1/H and /sup 13/C N. M. R. spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Funke, C.W.; Kaspersen, F.M.; Sperling, E.M.G.; Wagenaars, G.N.

    1986-03-15

    Replacement of /sup 12/C by /sup 14/C induces small upfield shifts of the directly bonded /sup 1/H and /sup 13/C nuclei; these shift differences can be used to measure the extent of /sup 14/C labelling.

  2. 2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: International collaborative study report

    International Nuclear Information System (INIS)

    An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the 2H/1H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the 13C/12C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the 18O/16O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations. The precision parameters of the method for measuring δ13C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 per mille , and the average reproducibility (R) was 0.91 per mille . As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the 2H/1H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources (δ13C and δ18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring δ18O were found to be similar to the values previously obtained for other methods applied to wine and fruit juices: the

  3. Relaxation-compensated difference spin diffusion NMR for detecting {sup 13}C–{sup 13}C long-range correlations in proteins and polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tuo; Williams, Jonathan K. [Massachusetts Institute of Technology, Department of Chemistry (United States); Schmidt-Rohr, Klaus [Brandeis University, Department of Chemistry (United States); Hong, Mei, E-mail: meihong@mit.edu [Massachusetts Institute of Technology, Department of Chemistry (United States)

    2015-02-15

    The measurement of long-range distances remains a challenge in solid-state NMR structure determination of biological macromolecules. In 2D and 3D correlation spectra of uniformly {sup 13}C-labeled biomolecules, inter-residue, inter-segmental, and intermolecular {sup 13}C–{sup 13}C cross peaks that provide important long-range distance constraints for three-dimensional structures often overlap with short-range cross peaks that only reflect the covalent structure of the molecule. It is therefore desirable to develop new approaches to obtain spectra containing only long-range cross peaks. Here we show that a relaxation-compensated modification of the commonly used 2D {sup 1}H-driven spin diffusion (PDSD) experiment allows the clean detection of such long-range cross peaks. By adding a z-filter to keep the total z-period of the experiment constant, we compensate for {sup 13}C T{sub 1} relaxation. As a result, the difference spectrum between a long- and a scaled short-mixing time spectrum show only long-range correlation signals. We show that one- and two-bond cross peaks equalize within a few tens of milliseconds. Within ∼200 ms, the intensity equilibrates within an amino acid residue and a monosaccharide to a value that reflects the number of spins in the local network. With T{sub 1} relaxation compensation, at longer mixing times, inter-residue and inter-segmental cross peaks increase in intensity whereas intra-segmental cross-peak intensities remain unchanged relative to each other and can all be subtracted out. Without relaxation compensation, the difference 2D spectra exhibit both negative and positive intensities due to heterogeneous T{sub 1} relaxation in most biomolecules, which can cause peak cancellation. We demonstrate this relaxation-compensated difference PDSD approach on amino acids, monosaccharides, a crystalline model peptide, a membrane-bound peptide and a plant cell wall sample. The resulting difference spectra yield clean multi-bond, inter

  4. - and Cross-Polarization 13C NMR Evidence of Alterations in Molecular Composition of Humic Substances Following Afforestation with Eucalypt in Distinct Brazilian Biomes

    Science.gov (United States)

    Silva, I. R.; Soares, E. M.; Schmidt-Rohr, K.; Novais, R.; Barros, N.; Fernandes, S.

    2010-12-01

    The effect of planting fast growing tree species on SOM quality in tropical regions has been overlooked. In the present study 13C-NMR approaches were used to evaluate the impact of eucalypt cultivation on humic and fulvic acids molecular composition. The results indicate that the replacement of native vegetation by eucalypt plantations increased the relative contribution of aliphatic groups in HA from soils previously under Atlantic Forest, Grassland, and the Cerrado (Curvelo site only). The same trend was observed for FA, except in the Curvelo site. A trend for degradation and smaller contribution of O-alkyl C (carbohydrates) in HA was observed in soils under eucalyptus in Atlantic Forest and Cerrado. For FA such decreases were seen in Cerrado and Grassland biomes after eucalypt planting. In the area cultivated with pasture in the Atlantic Forest biome and in the Grassland soil, the largest contributions of lignin-derived compounds were detected in HA. The HA from the Cerrado at the Curvelo site, where the woody vegetation is virtually devoid of grassy species, showed the lowest intensity of lignin signal then those from the Cerrado sensu stricto in Itacambira, where grass species are more abundant. At our study sites, charred material are most likely derived from burning of the native vegetation, as naturally occurs in the Cerrado region, or anthropogenic fires in the Grassland biome. Burning of harvest residues in eucalypt fields was also a common practice in the early rotations. The replacement of native vegetation by eucalypt plantations increases the relative contribution of nonpolar alkyl groups in HA from soils previously under Atlantic Forest, Grassland, and the Cerrado (Curvelo site only) biomes. There is evidence of substantial contribution of lignin-derived C to HA and FA, especially in sites planted with Brachiaria sp pastures. Eucalypt introduction decreases the relative contribution of carbohydrates in HA and FA. 13C DP/MAS NMR functional groups in

  5. In Situ 13C and 23Na Magic Angle Spinning NMR Investigation of Supercritical CO2 Incorporation in Smectite-Natural Organic Matter Composites

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, Geoffrey M.; Hoyt, David W.; Burton, Sarah D.; Ferguson, Brennan O.; Varga, Tamas; Kirkpatrick, Robert J.

    2014-01-29

    This paper presents an in situ NMR study of clay-natural organic polymer systems (a hectoritehumic acid [HA] composite) under CO2 storage reservoir conditions (90 bars CO2 pressure, 50°C). The 13C and 23Na NMR data show that supercritical CO2 interacts more strongly with the composite than with the base clay and does not react to form other C-containing species over several days at elevated CO2. With and without organic matter, the data suggest that CO2 enters the interlayer space of Na-hectorite equilibrated at 43% relative humidity. The presence of supercritical CO2 also leads to increased 23Na signal intensity, reduced line width at half height, increased basal width, more rapid 23Na T1 relaxation rates, and a shift to more positive resonance frequencies. Larger changes are observed for the hectorite-HA composite than for the base clay. In light of recently reported MD simulations of other polymer-Na-smectite composites, we interpret the observed changes as an increase in the rate of Na+ site hopping in the presence of supercritical CO2, the presence of potential new Na+ sorption sites when the humic acid is present, and perhaps an accompanying increase in the number of Na+ ions actively involved in site hopping. The results suggest that the presence of organic material either in clay interlayers or on external particle surfaces can significantly affect the behavior of supercritical CO2 and the mobility of metal ions in reservoir rocks.

  6. Application of (13)C ramp CPMAS NMR with phase-adjusted spinning sidebands (PASS) for the quantitative estimation of carbon functional groups in natural organic matter.

    Science.gov (United States)

    Ikeya, Kosuke; Watanabe, Akira

    2016-01-01

    The composition of carbon (C) functional groups in natural organic matter (NOM), such as dissolved organic matter, soil organic matter, and humic substances, is frequently estimated using solid-state (13)C NMR techniques. A problem associated with quantitative analysis using general cross polarization/magic angle spinning (CPMAS) spectra is the appearance of spinning side bands (SSBs) split from the original center peaks of sp (2) hybridized C species (i.e., aromatic and carbonyl C). Ramp CP/phase-adjusted side band suppressing (PASS) is a pulse sequence that integrates SSBs separately and quantitatively recovers them into their inherent center peaks. In the present study, the applicability of ramp CP/PASS to NOM analysis was compared with direct polarization (DPMAS), another quantitative method but one that requires a long operation time, and/or a ramp CP/total suppression side band (ramp CP/TOSS) technique, a popular but non-quantitative method for deleting SSBs. The test materials were six soil humic acid samples with various known degrees of aromaticity and two fulvic acids. There were no significant differences in the relative abundance of alkyl C, O-alkyl C, and aromatic C between the ramp CP/PASS and DPMAS methods, while the signal intensities corresponding to aromatic C in the ramp CP/TOSS spectra were consistently less than the values obtained in the ramp CP/PASS spectra. These results indicate that ramp CP/PASS can be used to accurately estimate the C composition of NOM samples.

  7. 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)

    A combination of three heteronuclear three-dimensional NMR experiments tailored for sequential resonance assignments in uniformly 15N, 13C-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 15N chemical shift dispersion in unfolded polypeptides, exploit the slow transverse 15N relaxation rates of unfolded polypeptides in high resolution constant-time [1H, 15N]-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 15N 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

  8. Early diagenesis of mangrove leaves in a tropical estuary: Bulk chemical characterization using solid-state 13C NMR and elemental analyses

    Science.gov (United States)

    Benner, R.; Hatcher, P.G.; Hedges, J.I.

    1990-01-01

    Changes in the chemical composition of mangrove (Rhizophora mangle) leaves during decomposition in tropical estuarine waters were characterized using solid-state 13C nuclear magnetic resonance (NMR) and elemental (CHNO) analysis. Carbohydrates were the most abundant components of the leaves accounting for about 50 wt% of senescent tissues. Tannins were estimated to account for about 20 wt% of leaf tissues, and lipid components, cutin, and possibly other aliphatic biopolymers in leaf cuticles accounted for about 15 wt%. Carbohydrates were generally less resistant to decomposition than the other constituents and decreased in relative concentration during decomposition. Tannins were of intermediate resistance to decomposition and remained in fairly constant proportion during decomposition. Paraffinic components were very resistant to decomposition and increased in relative concentration as decomposition progressed. Lignin was a minor component of all leaf tissues. Standard methods for the colorimetric determination of tannins (Folin-Dennis reagent) and the gravimetric determination of lignin (Klason lignin) were highly inaccurate when applied to mangrove leaves. The N content of the leaves was particularly dynamic with values ranging from 1.27 wt% in green leaves to 0.65 wt% in senescent yellow leaves attached to trees. During decomposition in the water the N content initially decreased to 0.51 wt% due to leaching, but values steadily increased thereafter to 1.07 wt% in the most degraded leaf samples. The absolute mass of N in the leaves increased during decomposition indicating that N immobilization was occurring as decomposition progressed. ?? 1990.

  9. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of O-desmethyltramadol hydrochloride an active metabolite in tramadol - An analgesic drug

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Marchewka, M. K.; Mohan, S.

    2014-03-01

    O-desmethyltramadol is one of the main metabolites of tramadol widely used clinically and has analgesic activity. The FTIR and FT-Raman spectra of O-desmethyl tramadol hydrochloride are recorded in the solid phase in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. Theoretical studies have been performed as its hydrochloride salt. The structure of the compound has been optimised with B3LYP method using 6-31G** and cc-pVDZ basis sets. The optimised bond length and bond angles are correlated with the X-ray data. The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT methods. The IR and Raman intensities are determined with B3LYP method using cc-pVDZ and 6-31G(d,p) basic sets. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/cc-pVDZ method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of O-desmethyltramadol hydrochloride has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecule have been anlysed.

  10. I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics

    Energy Technology Data Exchange (ETDEWEB)

    Ziegeweid, M.A.

    1995-11-29

    NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it is not possible to obtain well-resolved spectra in high magnetic fields. I have used a technique to observe {sup 14}N NQR resonances via their effect on neighboring protons mediated by the heteronuclear dipolar interaction to study peptides and narcotics. The sensitivity of the SQUID is not enough to measure low-frequency surface (or other low spin density) systems. The application of spin-polarized xenon has been previously used to enhance polarization in conventional NMR experiments. Because xenon only polarizes spins with which it is in contact, it is surface selective. While differences in chemical shifts between surface and bulk spins are not large, it is expected that the differences in quadrupole coupling constant should be very large due to the drastic change of the electric field gradient surrounding spins at the surface. With this in mind, I have taken preliminary steps to measure SQUID detected polarization transfer from Xe to another spin species at 4.2 K and in small magnetic fields (<50 G). In this regime, the spin-lattice relaxation of xenon is dependent on the applied magnetic field. The results of our efforts to characterize the relaxation of xenon are presented. The final section describes the solid-state variable-temperature (VT) one- and two-dimensional {sup 13}C cross polarization (CP)/magic angle spinning (MAS) NMR of Hf({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}({eta}{sup 1}-C{sub 5}H{sub 5}){sub 2}, Zr({eta}{sup 5}-C{sub 5}H{sub 5}){sub 3}({eta}{sup 1

  11. Stereochemistry of 16a-Hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene Established by 2D NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vagner Fernandes Knupp

    2009-02-01

    Full Text Available Friedelin (1, 3b-friedelinol (2, 28-hydroxyfriedelin (3, 16a-hydroxyfriedelin (4, 30-hydroxyfriedelin (5 and 16a,28-dihydroxyfriedelin (6 were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl3 solution, 16a-hydroxyfriedelin (4 reacted turning into 3-oxo-16-methylfriedel-16-ene (7. This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl3 solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY spectroscopy and mass spectrometry (GC-MS. It is also the first time that all the 13C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.

  12. In vivo measurement of ethanol metabolism in the rat liver using magnetic resonance spectroscopy of hyperpolarized [1-13C]pyruvate

    Science.gov (United States)

    Spielman, Daniel M.; Mayer, Dirk; Yen, Yi-Fen; Tropp, James; Hurd, Ralph E.; Pfefferbaum, Adolf

    2009-01-01

    [1-13C]pyruvate is readily polarizable substrate that has been the subject of numerous magnetic resonance spectroscopy (MRS) studies of in vivo metabolism. In this work, 13C-MRS of hyperpolarized [1-13C]pyruvate is used to interrogate a metabolic pathway involved in neither aerobic nor anaerobic metabolism. In particular, ethanol consumption leads to altered liver metabolism, which when excessive is associated with adverse medical conditions including fatty liver disease, hepatitis, cirrhosis, and cancer. Here we present a method for noninvasively monitoring this important process in vivo. Following the bolus injection of hyperpolarized [1-13C]pyruvate, we demonstrate a significantly increased rat liver lactate production rate with the co-administration of ethanol (P = 0.0016 unpaired t-test). The affect is attributable to increased liver nicotinamide adenine dinucleotide (NADH) associated with ethanol metabolism in combination with NADH's role as a coenzyme in pyruvate to lactate conversion. Beyond studies of liver metabolism, this novel in vivo assay of changes in NADH levels makes hyperpolarized [1-13C]pyruvate a potentially viable substrate for studying the multiple in vivo metabolic pathways that use NADH (or NAD+) as a coenzyme, thus broadening the range of applications that have been discussed in the literature to date. PMID:19526498

  13. Precise and accurate d13C analysis of rock samples using Flash Combustion–Cavity Ring Down Laser Spectroscopy

    DEFF Research Database (Denmark)

    Balslev-Clausen, David Morten; Dahl, Tais Wittchen; Saad, Nabil;

    2013-01-01

    The ratio of 13C to 12C in marine sedimentary rocks holds important clues to the evolution of the carbon cycle through Earth history. Isotopic analyses are traditionally carried out using isotope ratio mass spectrometry (IRMS), but this technique is both labor-intensive, expensive and requires...

  14. Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy, a new approach to study humic material?

    Science.gov (United States)

    Knicker, Heike; Lange, Sascha; van Rossum, Barth; Oschkinat, Hartmut

    2016-04-01

    Compared to solution NMR spectroscopy, solid-state NMR spectra suffer from broad resonance lines and low resolution. This could be overcome by the use of 2-dimenstional solid-state NMR pulse sequences. Until recently, this approach has been unfeasible as a routine tool in soil chemistry, mainly because of the low NMR sensitivity of the respective samples. A possibility to circumvent those sensitivity problems represents high-field Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy (Barnes et al., 2008), allowing considerable signal enhancements (Akbey et al., 2010). This is achieved by a microwave-driven transfer of polarization from a paramagnetic center to nuclear spins. Application of DNP to MAS spectra of biological systems (frozen solutions) showed enhancements of the factor 40 to 50 (Hall et al., 1997). Enhancements of this magnitude, thus may enable the use of at least some of the 2D solid-state NMR techniques that are presently already applied for pure proteins but are difficult to apply to soil peptides in their complex matrix. After adjusting the required acquisition parameters to the system "soil organic matter", lower but still promising enhancement factors were achieved. Additional optimization was performed and allowed the acquisition of 2D 13C and 15N solid-state NMR spectra of humified 13C and 15N enriched plant residues. Within the present contribution, the first solid-state DNP NMR spectra of humic material are presented. Those data demonstrate the great potential of this approach which certainly opens new doors for a better understanding of biochemical processes in soils, sediments and water. Akbey, Ü., Franks, W.T., Linden, A., Lange, S., Griffin, R.G., van Rossum, B.-J., Oschkinat, H., 2010. Dynamic nuclear polarization of deuterated proteins. Angewandte Chemie International Edition 49, 7803-7806. Barnes, A.B., De Paëpe, G., van der Wel, P.C.A., Hu, K.N., Joo, C.G., Bajaj, V.S., Mak-Jurkauskas, M.L., Sirigiri, J.R., Herzfeld, J

  15. Fast Identification of Radical Scavengers from Securigera varia by Combining 13C-NMR-Based Dereplication to Bioactivity-Guided Fractionation

    Directory of Open Access Journals (Sweden)

    Pacôme Sientzoff

    2015-08-01

    Full Text Available Securigera varia (Fabaceae is a common herbaceous perennial plant widely growing in Europe and Asia and purposely established for erosion control, roadside planting, and soil rehabilitation. The aim of this study was to determine the radical scavenging activity of a crude methanol extract of S. varia aerial parts by using the free radical DPPH (1,1-diphenyl-2-picrylhydrazyl and to rapidly identify the compounds involved in this activity. The crude extract was initially separated in five fractions on Diaion HP20 resin and the most active part was fractionated by Centrifugal Partition Extraction (CPE. Known compounds were directly identified by a 13C-NMR-based dereplication method. Semi-preparative high performance liquid chromatography purification experiments were further performed to identify unknown or minor active compounds. As a result, one new (13 and twelve known flavonoid glycosides together with three nitropropanoylglucopyranoses were isolated, including astragalin (1, kaempferol-3-O-(6-O-acetyl-β-D-glucopyranoside (2, kaempferol-3,4′-di-O-β-D-glucopyranoside (3, trifolin (4, isoquercitrin (5, hyperoside (6, isovitexin (7, isoorientin (8, isovitexin 4′-O-β-D-glucopyranoside (9, apigenin 7-O-β-D-glucuronopyranoside (10, luteolin 7-O-β-D-glucuronopyranoside (11, apigenin 7-O-α-L-rhamnopyranosyl-(1→2-β-D-glucuronopyranoside (12, apigenin 7-O-β-D-glucopyranosyl-(1→2-β-D-glucuronopyranoside (13, 6-O-(3-nitropropanoyl-β-D-glucopyranoside (14, coronillin (16 and coronarian (15. 120 mg of the most active compound isoorientin against the free radical DPPH was recovered by CPE with an HPLC purity of 99%.

  16. Supressão das anomalias de fase e batimentos laterais em espectros de RMN 13c obtidos com a sequência de precessão livre no estado estacionário Suppression of phase anomalies and sidebands on 13c NMR spectra obtained with the steady-state free precession sequence

    Directory of Open Access Journals (Sweden)

    Poliana Macedo dos Santos

    2010-01-01

    Full Text Available The Steady-State Free Precession (SSFP sequence has been widely used in low-field and low-resolution imaging NMR experiments to increase the signal-to-noise ratio (s/n of the signals. Here, we analyzed the Scrambled Steady State - SSS and Unscrambled Steady State - USS sequences to suppress phase anomalies and sidebands of the 13C NMR spectrum acquired in the SSFP regime. The results showed that the application of the USS sequence allowed a uniform distribution of the time interval between pulses (Tp, in the established time range, allowing a greater suppression of phase anomalies and sidebands, when compared with the SSS sequence.

  17. A straightforward method for stereospecific assignment of val and leu prochiral methyl groups by solid-state NMR: Scrambling in the [2-13C]Glucose labeling scheme

    Science.gov (United States)

    Lv, Guohua; Faßhuber, Hannes Klaus; Loquet, Antoine; Demers, Jean-Philippe; Vijayan, Vinesh; Giller, Karin; Becker, Stefan; Lange, Adam

    2013-03-01

    The unambiguous stereospecific assignment of the prochiral methyl groups in Val and Leu plays an important role in the structural investigation of proteins by NMR. Here, we present a straightforward method for their stereospecific solid-state NMR assignment based on [2-13C]Glucose ([2-13C]Glc) as the sole carbon source during protein expression. The approach is fundamentally based on the stereo-selective biosynthetic pathway of Val and Leu, and the co-presence of [2-13C]pyruvate produced mainly by glycolysis and [3-13C]/[1,3-13C]pyruvate most probably formed through scrambling in the pentose phosphate pathway. As a consequence, the isotope spin pairs 13Cβ-13Cγ2 and 13Cα-13Cγ1 in Val, and 13Cγ-13Cδ2 and 13Cβ-13Cδ1 in Leu are obtained. The approach is successfully demonstrated with the stereospecific assignment of the methyl groups of Val and Leu of type 3 secretion system PrgI needles and microcrystalline ubiquitin.

  18. 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.

    Directory of Open Access Journals (Sweden)

    Hiroshi Teramura

    Full Text Available 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.

  19. Structure determination of uniformly {sup 13}C, {sup 15}N labeled protein using qualitative distance restraints from MAS solid-state {sup 13}C-NMR observed paramagnetic relaxation enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Tamaki, Hajime [Hokkaido University, Graduate School of Life Science (Japan); Egawa, Ayako [Osaka University, Institute for Protein Research (Japan); Kido, Kouki [Hokkaido University, Graduate School of Life Science (Japan); Kameda, Tomoshi [National Institute of Advanced Industrial Science and Technology, Biotechnology Research Institute for Drug Discovery (Japan); Kamiya, Masakatsu; Kikukawa, Takashi; Aizawa, Tomoyasu [Hokkaido University, Faculty of Advanced Life Science (Japan); Fujiwara, Toshimichi [Osaka University, Institute for Protein Research (Japan); Demura, Makoto, E-mail: demura@sci.hokudai.ac.jp [Hokkaido University, Faculty of Advanced Life Science (Japan)

    2016-01-15

    Magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) is a powerful method for structure determination of insoluble biomolecules. However, structure determination by MAS solid-state NMR remains challenging because it is difficult to obtain a sufficient amount of distance restraints owing to spectral complexity. Collection of distance restraints from paramagnetic relaxation enhancement (PRE) is a promising approach to alleviate this barrier. However, the precision of distance restraints provided by PRE is limited in solid-state NMR because of incomplete averaged interactions and intermolecular PREs. In this report, the backbone structure of the B1 domain of streptococcal protein G (GB1) has been successfully determined by combining the CS-Rosetta protocol and qualitative PRE restraints. The derived structure has a Cα RMSD of 1.49 Å relative to the X-ray structure. It is noteworthy that our protocol can determine the correct structure from only three cysteine-EDTA-Mn{sup 2+} mutants because this number of PRE sites is insufficient when using a conventional structure calculation method based on restrained molecular dynamics and simulated annealing. This study shows that qualitative PRE restraints can be employed effectively for protein structure determination from a limited conformational sampling space using a protein fragment library.

  20. Structural comparison of oligoribonucleotides and their 2 -Deoxy-2 -fluoro analogs by heteronuclear NMR spectroscopy

    OpenAIRE

    Reif, Bernd; Wittmann, Valentin; Schwalbe, Harald; Griesinger, Christian; Wörner, Karlheinz; Jahn-Hofmann, Kerstin; Engels, Joachim W.; Bermel, Wolfgang

    1997-01-01

    1-(2-Deoxy-2-fluororibofuranosyl)pyrimidines were synthesized and incorporated into an RNA oligonucleotide to give 5-r[CfGCf(UfUfCfG)GCfG]-3 (Cf: short form of Cd2f2 = 2-deoxy-2-fluorocytidine; Uf: short form of Ud2f2 = 2-deoxy-2-fluorouridine). The oligomer was investigated by means of UV, CD, and NMR spectroscopy to address the question of how F-labels can substitute 13C-labels in the ribose ring. Through-space (NOE) and through-bond (scalar couplings) experiments were performed that make u...

  1. Metabolic response to exogenous ethanol in yeast: An in vivo statistical total correlation NMR spectroscopy approach

    Indian Academy of Sciences (India)

    Maso Ricci; Marianna Aggravi; Claudia Bonechi; Silvia Martini; Anna Maria; Claudio Rossi

    2012-09-01

    In vivo NMR spectroscopy, together with selectively 13C-labelled substrates and ‘statistical total correlation spectroscopy’ analysis (STOCSY), are valuable tools to collect and interpret the metabolic responses of a living organism to external stimuli. In this study, we applied this approach to evaluate the effects of increasing concentration of exogenous ethanol on the Saccharomyces cerevisiae fermentative metabolism. We show that the STOCSY analysis correctly identifies the different types of correlations among the enriched metabolites involved in the fermentation, and that these correlations are quite stable even in presence of a stressing factor such as the exogenous ethanol.

  2. Stereochemical investigations on the diketopiperazine derivatives of enalapril and lisinopril by NMR spectroscopy

    Science.gov (United States)

    Demeter, Ádám; Fodor, Tamás; Fischer, János

    1998-11-01

    Stereochemical analysis of epimeric diketopiperazine (DKP) derivatives of enalapril and lisinopril has been performed by NMR spectroscopy. The present study focuses on the configurational assignment and conformational characteristics of the epimeric DKPs obtained from cyclization and subsequent base-catalyzed hydrolysis. We report full 1H and 13C assignments as obtained by a concerted use of 1D and 2D methods. The configuration of the respective stereogenic centres and the main conformational features were derived from the measured scalar and NOE connections. One conspicuous conformational feature of the sidechain is its tendency to bend over the piperazinedione ring.

  3. The Doppler effect in NMR spectroscopy.

    Science.gov (United States)

    Guéron, Maurice

    2003-02-01

    An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

  4. FTIR and NDIR spectroscopies as valuable alternatives to IRMS spectrometry for the δ(13)C analysis of food.

    Science.gov (United States)

    Pironti, Concetta; Proto, Antonio; Camin, Federica; Cucciniello, Raffaele; Zarrella, Ilaria; Motta, Oriana

    2016-11-01

    The (13)C/(12)C carbon isotope ratio is a chemical parameter with many important applications in several scientific area and the technique of choice currently used for the δ(13)C determination is the isotope ratio mass spectrometry (IRMS). This latter is highly accurate (0.1‰) and sensitive (up to 0.01‰), but at the same time expensive and complex. The objective of this work was to assess the reliability of FTIR and NDIRS techniques for the measurement of carbon stable isotope ratio of food sample, in comparison to IRMS. IRMS, NDIRS and FTIR were used to analyze samples of food, such as oil, durum, cocoa, pasta and sugar, in order to determine the natural abundance isotopic ratio of carbon in a parallel way. The results were comparable, showing a close relationship among the three techniques. The main advantage in using FTIR and NDIRS is related to their cheapness and easy-to-operate in comparison to IRMS. PMID:27591614

  5. NMR spectroscopy and imaging of hyperpolarized gases

    OpenAIRE

    Zänker, Paul-Philipp

    2007-01-01

    Since the discovery of the nuclear magnetic resonance (NMR) phenomenon, countless NMR techniques have been developed that are today indispensable tools in physics, chemistry, biology, and medicine. As one of the main obstacles in NMR is its notorious lack of sensitivity, different hyperpolarization (HP) methods have been established to increase signals up to several orders of magnitude. In this work, different aspects of magnetic resonance, using HP noble gases, are studied, hereby combining ...

  6. Monitoring mammary tumor progression and effect of tamoxifen treatment in MMTV-PymT using MRI and magnetic resonance spectroscopy with hyperpolarized [1-13C]pyruvate

    DEFF Research Database (Denmark)

    Asghar Butt, Sadia; Søgaard, Lise V.; Ardenkjær-Larsen, Jan Henrik;

    2015-01-01

    Purpose: To use dynamic magnetic resonance spectroscopy (MRS) of hyperpolarized 13C-pyruvate to follow the progress over time in vivo of breast cancer metabolism in the MMTV-PymT model, and to follow the response to the anti-estrogen drug tamoxifen. Methods: Tumor growth was monitored by anatomical...... MRI by measuring tumor volumes. Dynamic MRS of hyperpolarized 13C was used to measure an "apparent" pyruvate-to-lactate rate constant (kp) of lactate dehydrogenase (LDH) in vivo. Further, ex vivo pathology and in vitro LDH initial reaction velocity were evaluated. Results: Tamoxifen significantly...... halted the tumor growth measured as tumor volume by MRI. In the untreated animals, kp correlated with tumor growth. The kP was somewhat but not significantly lower in the treated group. Studies in vitro confirmed the effects of tamoxifen on tumor growth, and here the LDH reaction velocity was reduced...

  7. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    Energy Technology Data Exchange (ETDEWEB)

    Atreya, H.S.; Chary, K.V.R. [Tata Institute of Fundamental Research, Department of Chemical Sciences (India)

    2001-03-15

    A novel methodology for stereospecific NMR assignments of methyl (CH{sub 3}) groups of Val and Leu residues in fractionally {sup 13}C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally {sup 13}C-labeling the rest. A 2D [{sup 13}C-{sup 1}H] HSQC spectrum recorded on such a sample is devoid of peaks belonging to the 'unlabeled' amino acid residues. Such spectral simplification aids in unambiguous stereospecific assignment of diastereotopic CH{sub 3} groups in Val and Leu residues in large proteins. This methodology has been demonstrated on a 15 kDa calcium binding protein from Entamoeba histolytica (Eh-CaBP)

  8. Identification, synthesis and characterization of an unknown process related impurity in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI–IT/MS, 1H, 13C and 1H–1H COSY NMR

    OpenAIRE

    Saji Thomas; Saroj Kumar Paul; Subhash Chandra Joshi; Vineet Kumar; Ashutosh Agarwal; Dharam Vir

    2014-01-01

    A new impurity was detected during high performance liquid chromatographic (HPLC) analysis of eslicarbazepine acetate active pharmaceutical ingredient. The structure of unknown impurity was postulated based on liquid chromatography mass spectrometry using electrospray ionization and ion trap analyzer (LC/ESI–IT/MS) analysis. Proposed structure of impurity was unambiguously confirmed by synthesis followed by characterization using 1H, 13C nuclear magnetic resonance spectrometry (NMR), 1H–1H co...

  9. Developments of RF Coil for P in vivo NMR Spectroscopy .

    Directory of Open Access Journals (Sweden)

    S. Khushu

    1993-07-01

    Full Text Available RF receiver coils are very important parts of an NMR System. The design of these coils is very critical and has a dramatic effect on the SNR of the NMR signal and are generally developed in TRA/REC mode. This paper reports the developments of a 3.5 cm TRA/REC 26 MHz RF coil for P spectroscopy of small organs like thyroid. The coil is small in size, fits well in the neck for thyroid spectroscopy and is successfully working with the 1.5 tesla whole body Superconducting NMR System available at INMAS.

  10. Developments of RF Coil for P in vivo NMR Spectroscopy .

    OpenAIRE

    S. Khushu; S.B. Mehta; Sushil Chandra; A Jena

    1993-01-01

    RF receiver coils are very important parts of an NMR System. The design of these coils is very critical and has a dramatic effect on the SNR of the NMR signal and are generally developed in TRA/REC mode. This paper reports the developments of a 3.5 cm TRA/REC 26 MHz RF coil for P spectroscopy of small organs like thyroid. The coil is small in size, fits well in the neck for thyroid spectroscopy and is successfully working with the 1.5 tesla whole body Superconducting NMR System availab...

  11. Hypermetabolic state in the 7-month-old triple transgenic mouse model of Alzheimer's disease and the effect of lipoic acid: a 13C-NMR study.

    Science.gov (United States)

    Sancheti, Harsh; Patil, Ishan; Kanamori, Keiko; Díaz Brinton, Roberta; Zhang, Wei; Lin, Ai-Ling; Cadenas, Enrique

    2014-11-01

    Alzheimer's disease (AD) is characterized by age-dependent biochemical, metabolic, and physiologic changes. These age-dependent changes ultimately converge to impair cognitive functions. This study was carried out to examine the metabolic changes by probing glucose and tricarboxylic acid cycle metabolism in a 7-month-old triple transgenic mouse model of AD (3xTg-AD). The effect of lipoic acid, an insulin-mimetic agent, was also investigated to examine its ability in modulating age-dependent metabolic changes. Seven-month-old 3xTg-AD mice were given intravenous infusion of [1-(13)C]glucose followed by an ex vivo (13)C nuclear magnetic resonance to determine the concentrations of (13)C-labeled isotopomers of glutamate, glutamine, aspartate, gamma aminobutyric acid, and N-acetylaspartate. An intravenous infusion of [1-(13)C]glucose+[1,2-(13)C]acetate was given for different periods of time to distinguish neuronal and astrocytic metabolism. Enrichments of glutamate, glutamine, and aspartate were calculated after quantifying the total ((12)C+(13)C) concentrations by high-performance liquid chromatography. A hypermetabolic state was clearly evident in 7-month-old 3xTg-AD mice in contrast to the hypometabolic state reported earlier in 13-month-old mice. Hypermetabolism was evidenced by prominent increase of (13)C labeling and enrichment in the 3xTg-AD mice. Lipoic acid feeding to the hypermetabolic 3xTg-AD mice brought the metabolic parameters to the levels of nonTg mice. PMID:25099753

  12. An Oral Load of [13C3]Glycerol and Blood NMR Analysis Detect Fatty Acid Esterification, Pentose Phosphate Pathway, and Glycerol Metabolism through the Tricarboxylic Acid Cycle in Human Liver.

    Science.gov (United States)

    Jin, Eunsook S; Sherry, A Dean; Malloy, Craig R

    2016-09-01

    Drugs and other interventions for high impact hepatic diseases often target biochemical pathways such as gluconeogenesis, lipogenesis, or the metabolic response to oxidative stress. However, traditional liver function tests do not provide quantitative data about these pathways. In this study, we developed a simple method to evaluate these processes by NMR analysis of plasma metabolites. Healthy subjects ingested [U-(13)C3]glycerol, and blood was drawn at multiple times. Each subject completed three visits under differing nutritional states. High resolution (13)C NMR spectra of plasma triacylglycerols and glucose provided new insights into a number of hepatic processes including fatty acid esterification, the pentose phosphate pathway, and gluconeogenesis through the tricarboxylic acid cycle. Fasting stimulated pentose phosphate pathway activity and metabolism of [U-(13)C3]glycerol in the tricarboxylic acid cycle prior to gluconeogenesis or glyceroneogenesis. Fatty acid esterification was transient in the fasted state but continuous under fed conditions. We conclude that a simple NMR analysis of blood metabolites provides an important biomarker of pentose phosphate pathway activity, triacylglycerol synthesis, and flux through anaplerotic pathways in mitochondria of human liver.

  13. Tricarboxylic acid cycle activity measured by 13C magnetic resonance spectroscopy in rats subjected to the kaolin model of obstructed hydrocephalus

    DEFF Research Database (Denmark)

    Melø, Torun M; Håberg, Asta K; Risa, Øystein;

    2011-01-01

    Evaluating early changes in cerebral metabolism in hydrocephalus can help in the decision making and the timing of surgical intervention. This study was aimed at examining the tricarboxylic acid (TCA) cycle rate and (13)C label incorporation into neurotransmitter amino acids and other compounds 2...... weeks after rats were subjected to kaolin-induced progressive hydrocephalus. In vivo and ex vivo magnetic resonance spectroscopy (MRS), combined with the infusion of [1,6-(13)C]glucose, was used to monitor the time courses of (13)C label incorporation into the different carbon positions of glutamate...... in the forebrains of rats with hydrocephalus as well as in those of controls. Metabolic rates were determined by fitting the measured data into a one-compartment metabolic model. The TCA cycle rate was 1.3 ± 0.2 μmoles/gram/minute in the controls and 0.8 ± 0.4 μmoles/gram/minute in the acute hydrocephalus group...

  14. FT-IR spectroscopy and density functional theory calculations of 13C isotopologues of the helical peptide Z-Aib6-OtBu.

    Science.gov (United States)

    Zeko, Timothy; Hannigan, Steven F; Jacisin, Timothy; Guberman-Pfeffer, Matthew J; Falcone, Eric R; Guildford, Melissa J; Szabo, Christopher; Cole, Kathryn E; Placido, Jessica; Daly, Erin; Kubasik, Matthew A

    2014-01-01

    Isotope-edited FT-IR spectroscopy is a combined synthetic and spectroscopic method used to characterize local (e.g., residue-level) vibrational environments of biomolecules. We have prepared the 3(10) helical peptide Z-Aib6-OtBu and seven (13)C-enriched analogues that vary only in the number and position(s) of (13)C═O isotopic enrichment. FT-IR spectra of these eight peptides solvated in the nonpolar aprotic solvent dichloromethane have been collected and compared to frequency, intensity, and normal mode results of DFT calculations. Single (13)C enrichment of amide functional groups tends to localize amide I vibrational eigenmodes, providing residue-specific information regarding the local environment (e.g., hydrogen bonding or solvent exposure) of the peptide bond. Double (13)C enrichment of Z-Aib6-OtBu allows for examination of interamide coupling between two labeled amide functional groups, providing experimental evidence of interamide coupling in the context of 3(10) helical structure. Although the calculated and observed interamide couplings of Z-Aib6-OtBu are a few cm(-1) and less, the eight peptides exhibit distinct infrared spectra, revealing details of interamide coupling and residue level vibrational environments.

  15. Mass spectrometry and /sup 13/C nuclear magnetic resonance spectroscopy of compounds modeling the glycopeptide linkage of glycoproteins

    Energy Technology Data Exchange (ETDEWEB)

    Blumberg, K.; Bush, C.A.

    1982-01-15

    The properties of several compounds useful as models for three-dimensional conformational studies and the investigation of the chemical degradation of glycopeptide linkages both of the N- and O-glycosidic type are described. Using the method of differential chemical shift in H/sub 2/O and D/sub 2/O as solvents, the carbon NMR spectrum of N-acetylglucosaminylasparagine, 1-N-acetyl-..beta..-D-glucopyranosylamine, and 1-N-acetyl-2-acetamido-..beta..-D-glycopyranosylamine has been assigned. Electron impact mass spectra of the peracetylated derivatives of the latter two compounds show a peak apparently unique to glycopyranosylamides at m/e = 269, no analog of which is observed in the mass spectra of other peracetylated sugars. As models of the ..cap alpha..-O-glycosidic linkage, fully assigned carbon NMR spectra of ..cap alpha..-methyl-N-acetylgalactosamine (GalNAc), ..cap alpha..-methyl-3-O-methyl GalNAc, and -GlcNAc as well as the disaccharide Glc-..beta..-l ..-->.. 3 GalNAc are reported. Because certain anomalies in the chemical shifts and /sup 1/J/sub CH/ observed in the disaccharide and in O-glycosylated glycoproteins are not observed in the simple model compounds, they may result from conformational interactions in the glycopeptides.

  16. Model free approach to kinetic analysis of real-time hyperpolarized 13C magnetic resonance spectroscopy data.

    Directory of Open Access Journals (Sweden)

    Deborah K Hill

    Full Text Available Real-time detection of the rates of metabolic flux, or exchange rates of endogenous enzymatic reactions, is now feasible in biological systems using Dynamic Nuclear Polarization Magnetic Resonance. Derivation of reaction rate kinetics from this technique typically requires multi-compartmental modeling of dynamic data, and results are therefore model-dependent and prone to misinterpretation. We present a model-free formulism based on the ratio of total areas under the curve (AUC of the injected and product metabolite, for example pyruvate and lactate. A theoretical framework to support this novel analysis approach is described, and demonstrates that the AUC ratio is proportional to the forward rate constant k. We show that the model-free approach strongly correlates with k for whole cell in vitro experiments across a range of cancer cell lines, and detects response in cells treated with the pan-class I PI3K inhibitor GDC-0941 with comparable or greater sensitivity. The same result is seen in vivo with tumor xenograft-bearing mice, in control tumors and following drug treatment with dichloroacetate. An important finding is that the area under the curve is independent of both the input function and of any other metabolic pathways arising from the injected metabolite. This model-free approach provides a robust and clinically relevant alternative to kinetic model-based rate measurements in the clinical translation of hyperpolarized (13C metabolic imaging in humans, where measurement of the input function can be problematic.

  17. Real-time analysis of δ13C- and δD-CH4 in ambient air with laser spectroscopy: method development and first intercomparison results

    Directory of Open Access Journals (Sweden)

    S. Eyer

    2015-08-01

    Full Text Available In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS to a preconcentration unit, called TRace gas EXtractor (TREX. This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, μmole/mole methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on replicate measurements of compressed air during a two-week intercomparison campaign, the repeatability of the TREX-QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass-spectrometry (IRMS based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. Thus, the intercomparison also reveals the need for reference air samples with accurately determined isotopic composition of CH4 to further improve the interlaboratory compatibility.

  18. Generic applications of (13) C-detected NMR diffusion to formulated systems with suppression of thermal convection induced by proton decoupling.

    Science.gov (United States)

    Hou, Jianbo; He, Yiyong; Sabatino, Paolo; Yuan, Ling; Redwine, David

    2016-07-01

    Fast and effective structural/compositional analysis on formulated systems represents one of the major challenges encountered in analytical science. (13) C-detected diffusion represents a promising tool to tackle the aforementioned challenges, particularly in industry. Toward exploring the generic applications of (13) C-detected diffusion, thermal convection induced by (1) H decoupling has been identified as a key factor that resulted in significantly reduced resolution in the diffusion dimension. Optimization of experimental parameters and utilization of double-stimulated echo-based pulse sequence both can effectively suppress the thermal convection caused by the (1) H decoupling, the success of which allows robust and generic applications of (13) C-detected diffusion to systems from mixtures of small molecules, polymer blends, and copolymers to actual complex formulated systems. The method is particularly powerful in differentiating small molecules from polymers, polymer blends from copolymers, and end-group analysis. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26845387

  19. High-Precision Measurement of 13C/12C Isotopic Ratio Using Gas Chromatography-Combustion-Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Saad, N.; Kuramoto, D. S.; Haase, C.; Crosson, E.; Tan, S.; Zare, R. N.

    2009-12-01

    Light stable isotope analysis, and in particular, compound specific isotopic analysis (CSIA), is a valuable tool to elucidate pathways and provide a better insight into biological, ecological, and geological systems. We present here the results of compound-specific isotopic carbon analysis of short chain hydrocarbons using the world’s first combination of gas chromatography, combustion interface, and cavity ring-down spectroscopy (GC-C-CRDS). Cavity ring-down spectroscopy (CRDS) is a highly sensitive optical spectroscopy, one application of which is to measure the stable isotopic ratios in small molecules. Because it uses a highly reflective optical cavity with many kilometers effective path length, CRDS provides some of the most sensitive and precise optical absorption measurements. Most optical spectroscopy isotopic analysis measures the quantities of each isotopologue independently using their distinct ro-vibrational spectra. The most common isotopes measured with optical spectroscopy are 13C and 12C in carbon dioxide. However, the isotopes of hydrogen, oxygen, and sulfur have also been measured. Unlike isotope ratio mass spectrometry (IRMS), optical spectroscopy can distinguish among isobars, which have essentially identical m/z ratios. The combination of chemical separation, chemical conversion, and CRDS makes a nearly universal tool for isotopic analysis of mixtures. In addition, CRDS can tolerate a variety of compounds mixed with the target. For example, CRDS can measure carbon dioxide and its isotopic 13C/12C ratio in the presence of oxygen. Using the novel GC-C-CRDS system, we injected a 75-microliter mixture of approximately equal quantities of methane, ethane, and propane into a gas chromatograph using helium as carrier gas. The methane, ethane, and propane were separated in time by 100 to 200 seconds after the chromatograph. Oxygen gas was added, and the hydrocarbons were combusted in a catalytic combustor with platinum and nickel, held at 1150oC. The

  20. Solid-State NMR Spectroscopy for the Physical Chemistry Laboratory

    Science.gov (United States)

    Kinnun, Jacob J.; Leftin, Avigdor; Brown, Michael F.

    2013-01-01

    Solid-state nuclear magnetic resonance (NMR) spectroscopy finds growing application to inorganic and organic materials, biological samples, polymers, proteins, and cellular membranes. However, this technique is often neither included in laboratory curricula nor typically covered in undergraduate courses. On the other hand, spectroscopy and…

  1. Post-translational heterocyclic backbone modifications in the 43-peptide antibiotic microcin B17. Structure elucidation and NMR study of a 13C,15N-labelled gyrase inhibitor.

    Science.gov (United States)

    Bayer, A; Freund, S; Jung, G

    1995-12-01

    Microcin B17 (McB17), the first known gyrase inhibitor of peptidic nature, is produced by ribosomal synthesis and post-translational modification of the 69-residue precursor protein by an Escherichia coli strain. To elucidate the chemical structure of the mature 43-residue peptide antibiotic, fermentation and purification protocols were established and optimized which allowed the isolation and purification of substantial amounts of highly pure McB17 (non-labelled, 15N-labelled and 13C/15N-labelled peptide. By ultraviolet-absorption spectroscopy. HPLC-electrospray mass spectrometry and GC-mass spectrometry, amino acid analysis, protein sequencing, and, in particular, multidimensional NMR, we could demonstrate and unequivocally prove that the enzymic modification of the precursor backbone at Gly-Cys and Gly-Ser segments leads to the formation of 2-aminomethylthiazole-4-carboxylic acid and 2-aminomethyloxazole-4-carboxylic acid, respectively. In addition, two bicyclic modifications 2-(2-aminomethyloxazolyl)thiazole-4-carboxylic acid and 2-(2-aminomethylthiazolyl)oxazole-4-carboxylic acid were found that consist of directly linked thiazole and oxazole rings derived from one Gly-Ser-Cys and one Gly-Cys-Ser segment. Analogous to the thiazole and oxazole rings found in antitumor peptides of microbial and marine origin, these heteroaromatic ring systems of McB17 presumably play an important role in its gyrase-inhibiting activity, e.g. interacting with the DNA to trap the covalent protein-DNA intermediate of the breakage-reunion reaction of the gyrase.

  2. Genetic algorithm optimized triply compensated pulses in NMR spectroscopy.

    Science.gov (United States)

    Manu, V S; Veglia, Gianluigi

    2015-11-01

    Sensitivity and resolution in NMR experiments are affected by magnetic field inhomogeneities (of both external and RF), errors in pulse calibration, and offset effects due to finite length of RF pulses. To remedy these problems, built-in compensation mechanisms for these experimental imperfections are often necessary. Here, we propose a new family of phase-modulated constant-amplitude broadband pulses with high compensation for RF inhomogeneity and heteronuclear coupling evolution. These pulses were optimized using a genetic algorithm (GA), which consists in a global optimization method inspired by Nature's evolutionary processes. The newly designed π and π/2 pulses belong to the 'type A' (or general rotors) symmetric composite pulses. These GA-optimized pulses are relatively short compared to other general rotors and can be used for excitation and inversion, as well as refocusing pulses in spin-echo experiments. The performance of the GA-optimized pulses was assessed in Magic Angle Spinning (MAS) solid-state NMR experiments using a crystalline U-(13)C, (15)N NAVL peptide as well as U-(13)C, (15)N microcrystalline ubiquitin. GA optimization of NMR pulse sequences opens a window for improving current experiments and designing new robust pulse sequences. PMID:26473327

  3. NMR Spectroscopy: Processing Strategies (by Peter Bigler)

    Science.gov (United States)

    Mills, Nancy S.

    1998-06-01

    Peter Bigler. VCH: New York, 1997. 249 pp. ISBN 3-527-28812-0. $99.00. This book, part of a four-volume series planned to deal with all aspects of a standard NMR experiment, is almost the exact book I have been hoping to find. My department has acquired, as have hundreds of other undergraduate institutions, high-field NMR instrumentation and the capability of doing extremely sophisticated experiments. However, the training is often a one- or two-day experience in which the material retained by the faculty trained is garbled and filled with holes, not unlike the information our students seem to retain. This text, and the accompanying exercises based on data contained on a CD-ROM, goes a long way to fill in the gaps and clarify misunderstandings about NMR processing.

  4. In situ solid-state NMR spectroscopy of electrochemical cells: batteries, supercapacitors, and fuel cells.

    Science.gov (United States)

    Blanc, Frédéric; Leskes, Michal; Grey, Clare P

    2013-09-17

    prevent dendrite formation. The in situ method was also applied to monitor (by (11)B NMR) electrochemical double-layer formation in supercapacitors in real time. Though this method is useful, it comes with challenges. The separation of the contributions from the different cell components in the NMR spectra is not trivial because of overlapping resonances. In addition, orientation-dependent NMR interactions, including the spatial- and orientation-dependent bulk magnetic susceptibility (BMS) effects, can lead to resonance broadening. Efforts to understand and mitigate these BMS effects are discussed in this Account. The in situ NMR investigation of fuel cells initially focused on the surface electrochemistry at the electrodes and the electrochemical oxidation of methanol and CO to CO2 on the Pt cathode. On the basis of the (13)C and (195)Pt NMR spectra of the adsorbates and electrodes, CO adsorbed on Pt and other reaction intermediates and complete oxidation products were detected and their mode of binding to the electrodes investigated. Appropriate design and engineering of the NMR hardware has allowed researchers to integrate intact direct methanol fuel cells into NMR probes. Chemical transformations of the circulating methanol could be followed and reaction intermediates could be detected in real time by either (2)H or (13)C NMR spectroscopy. By use of the in situ NMR approach, factors that control fuel cell performance, such as methanol cross over and catalyst performance, were identified.

  5. In situ solid-state NMR spectroscopy of electrochemical cells: batteries, supercapacitors, and fuel cells.

    Science.gov (United States)

    Blanc, Frédéric; Leskes, Michal; Grey, Clare P

    2013-09-17

    prevent dendrite formation. The in situ method was also applied to monitor (by (11)B NMR) electrochemical double-layer formation in supercapacitors in real time. Though this method is useful, it comes with challenges. The separation of the contributions from the different cell components in the NMR spectra is not trivial because of overlapping resonances. In addition, orientation-dependent NMR interactions, including the spatial- and orientation-dependent bulk magnetic susceptibility (BMS) effects, can lead to resonance broadening. Efforts to understand and mitigate these BMS effects are discussed in this Account. The in situ NMR investigation of fuel cells initially focused on the surface electrochemistry at the electrodes and the electrochemical oxidation of methanol and CO to CO2 on the Pt cathode. On the basis of the (13)C and (195)Pt NMR spectra of the adsorbates and electrodes, CO adsorbed on Pt and other reaction intermediates and complete oxidation products were detected and their mode of binding to the electrodes investigated. Appropriate design and engineering of the NMR hardware has allowed researchers to integrate intact direct methanol fuel cells into NMR probes. Chemical transformations of the circulating methanol could be followed and reaction intermediates could be detected in real time by either (2)H or (13)C NMR spectroscopy. By use of the in situ NMR approach, factors that control fuel cell performance, such as methanol cross over and catalyst performance, were identified. PMID:24041242

  6. Solid-state 13C NMR study of banana liquid crystals - 3: Alkyl-tail-group packing environments of an acute-angle bent-core molecule in the hexagonal columnar and cubic phases

    Science.gov (United States)

    Kurosu, Hiromichi; Endo, Yumi; Kimura, Saori; Hashimoto, Tomoko; Harada, Motoi; Lee, Eun-Woo; Sone, Masato; Watanabe, Junji; Kang, Sungmin

    2016-02-01

    Solid-state 13C nuclear magnetic resonance (NMR) measurements were performed on the hexagonal columnar and cubic phases of an acute-angle banana-shaped molecule, N(1,7)-S30. In the hexagonal columnar phase, three peaks appear at the NMR chemical shifts assigned to the internal methylene carbons of alkyl tails, indicating that the two alkyl tails have different packing structures, and one of the tails has two different conformations within a single molecule. Combined cross-polarization/magic-angle spinning and pulse saturation transfer/magic-angle spinning measurements show that one of the alkyl chains is located inside and the other is located outside the columnar structure. In the cubic phase, pulse saturation transfer/magic-angle spinning measurement shows that only one peak appears at the NMR chemical shifts assigned to the internal methylene carbons of alkyl tails, indicating that both of the alkyl chains are located outside the cubic structure.

  7. In-situ annotation of carbohydrate diversity, abundance, and degradability in highly complex mixtures using NMR spectroscopy

    DEFF Research Database (Denmark)

    Meier, Sebastian

    2014-01-01

    Many functions of carbohydrates depend on the detection of short structural motifs, approximately up to hexasaccharide length, by receptors or catalysts. This study investigates the usefulness of state-of-the-art 1H–13C nuclear-magnetic-resonance (NMR) spectroscopy for characterizing the diversity......, abundance, and degradability of such short structural motifs in plant-derived carbohydrates. Assignments of carbohydrate signals for 1H–13C NMR spectra of beer, wine, and fruit juice yield up to >130 assignments in situ, i.e. in individual samples without separation or derivatization. More than 500...... structural motifs can be resolved over a concentration range of ~103 in experiments of a few hours duration. The diversity of carbohydrate units increases according to power laws at lower concentrations for both cereal and fruit-derived samples. Simple graphs resolve the smaller overall contribution of more...

  8. Room temperature chiral discrimination in paramagnetic NMR spectroscopy

    CERN Document Server

    Soncini, Alessandro

    2016-01-01

    A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization $\\mathbf{P}$ rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. $\\mathbf{140}$, 011103 (2014)], is here generalized to paramagnetic systems. Our theory predicts new contributions to $\\mathbf{P}$, varying as the square of the inverse temperature. Ab initio calculations for ten Dy$^{3+}$ complexes, at 293K, show that in strongly anisotropic paramagnetic molecules $\\mathbf{P}$ can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.

  9. 1H, 15N and 13C NMR resonance assignment, secondary structure and global fold of the FMN-binding domain of human cytochrome P450

    International Nuclear Information System (INIS)

    The FMN-binding domain of human NADPH-cytochrome P450 reductase,corresponding to exons 3-;7, has been expressed at high level in an active form and labelled with 13C and 15N. Most of the backbone and aliphatic side-chain 1H, 15Nand 13C resonances have been assigned using heteronuclear double- and triple-resonance methods, together with a semiautomatic assignment strategy. The secondary structure as estimated from the chemical shift index and NOE connectivities consists of six α-helices and fiveβ-strands. The global fold was deduced from the long-range NOE sun ambiguously assigned in a 4D 13C-resolved HMQC-NOESY-HMQC spectrum. The fold is of the alternating α/β type, with the fiveβ-strands arranged into a parallel β-sheet. The secondary structure and global fold are very similar to those of the bacterial flavodoxins, but the FMN-binding domain has an extra short helix in place of a loop, and an extra helix at the N-terminus (leading to the membrane anchordomain in the intact P450 reductase). The experimental constraints were combined with homology modelling to obtain a structure of the FMN-bindingdomain satisfying the observed NOE constraints. Chemical shift comparisons showed that the effects of FMN binding and of FMN reduction are largely localised at the binding site

  10. Open-Source Automated Parahydrogen Hyperpolarizer for Molecular Imaging Using (13)C Metabolic Contrast Agents.

    Science.gov (United States)

    Coffey, Aaron M; Shchepin, Roman V; Truong, Milton L; Wilkens, Ken; Pham, Wellington; Chekmenev, Eduard Y

    2016-08-16

    An open-source hyperpolarizer producing (13)C hyperpolarized contrast agents using parahydrogen induced polarization (PHIP) for biomedical and other applications is presented. This PHIP hyperpolarizer utilizes an Arduino microcontroller in conjunction with a readily modified graphical user interface written in the open-source processing software environment to completely control the PHIP hyperpolarization process including remotely triggering an NMR spectrometer for efficient production of payloads of hyperpolarized contrast agent and in situ quality assurance of the produced hyperpolarization. Key advantages of this hyperpolarizer include: (i) use of open-source software and hardware seamlessly allowing for replication and further improvement as well as readily customizable integration with other NMR spectrometers or MRI scanners (i.e., this is a multiplatform design), (ii) relatively low cost and robustness, and (iii) in situ detection capability and complete automation. The device performance is demonstrated by production of a dose (∼2-3 mL) of hyperpolarized (13)C-succinate with %P13C ∼ 28% and 30 mM concentration and (13)C-phospholactate at %P13C ∼ 15% and 25 mM concentration in aqueous medium. These contrast agents are used for ultrafast molecular imaging and spectroscopy at 4.7 and 0.0475 T. In particular, the conversion of hyperpolarized (13)C-phospholactate to (13)C-lactate in vivo is used here to demonstrate the feasibility of ultrafast multislice (13)C MRI after tail vein injection of hyperpolarized (13)C-phospholactate in mice. PMID:27478927

  11. Synthesis and 1H and 13C NMR spectral study of some r(2),c(4)-bis(isopropylcarbonyl)-c(5)-hydroxy-t(5)-methyl-t(3)-substituted phenyl, cyclohexanones and their oximes

    Science.gov (United States)

    Balachander, R.; Sameera, S. A.; Mohan, R. T. Sabapathy

    2016-07-01

    All the synthesized compounds have been characterized by 1H, 13C, 2D NMR and mass spectral studies. The spectral data suggest that compounds 2, 3, 5 and 6 exist in chair conformation with axial orientation of the hydroxyl group and equatorial orientations of all the other substituent. Long-range coupling is observed between OH proton to H-6a proton should be in a W arrangement. Compounds 1 and 4 diamagnetic anisotropic effect of the furyl group is not pronounced and absence of long-rang coupling between OH proton to H-6a proton. The oximation effects were discussed to all synthesized compounds using 1H and 13C chemical shifts.

  12. Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of 13C chemical shifts

    Directory of Open Access Journals (Sweden)

    Simone Di Micco

    2013-12-01

    Full Text Available In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of 13C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

  13. C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy; Application in patients with breast lesions

    Energy Technology Data Exchange (ETDEWEB)

    Fossell, E.T.; Hall, F.M. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Radiology); McDonagh, J. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Pathology)

    1991-05-01

    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.

  14. Phosphorus-31, 15N, and 13C NMR of glyphosate: Comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase

    International Nuclear Information System (INIS)

    The herbicidal dead-end ternary complex (ES3PGlyph) of glyphosate [N-(phosphonomethyl)glycine] with 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) and the substrate shikimate 3-phosphate (S3P) has been characterized by 31P, 15N, and 13C NMR. The NMR spectra of EPSPS-bound glyphosate show unique chemical shifts (δ) for each of the three nuclei. By 31P NMR, glyphosate in the dead-end complex is a distinct species 3.5 ppm downfield from free glyphosate. The 13C signal of glyphosate in the dead-end complex is shifted 4 ppm downfield from that of free glyphosate. The 15N signal for glyphosate (99%) in the dead-end complex is 5 ppm further downfield than that of any free zwitterionic species and 10 ppm downfield from that of the average free species at pH 10.1. The structures of each ionic state of glyphosate are modeled with force field calculations by using MacroModel. A correlation is made for the 31P δ and the C-P-O bond angle, and the 13C and 15N δ values are postulated to be related to C-C-O and C-N-C bond angles, respectively. The downfield 31P chemical shift perturbation for S3P in the EPSPS binary complex is consistent with ionization of the 3-phosphate of S3P upon binding. Comparison with the S3P 31P δ vs pH titration curve specifies predominantly the dianion of the 3-phosphate in the ES3P binary complex, while the ES3PGlyph complex indicates net protonation at the 3-phosphate. Chemical shift perturbations of this latter type may be explained by changes in the O-P-O bond angle

  15. High resolution {sup 13}C NMR spectra on oriented lipid bilayers: From quantifying the various sources of line broadening to performing 2D experiments with 0.2-0.3 ppm resolution in the carbon dimension

    Energy Technology Data Exchange (ETDEWEB)

    Soubias, O.; Saurel, O.; Reat, V.; Milon, A. [Institut de Pharmacologie et de Biologie Structurale (France)], E-mail: alain.milon@ipbs.fr

    2002-09-15

    {sup 13}C NMR spectra routinely performed on oriented lipid bilayers display linewidth of 1-2 ppm, although T{sub 2} measurements indicate that 0.1-0.2 ppm could be obtained. We have prepared a DMPC - {sup 13}C{sub 4}-cholesterol (7/3) sample, and oriented the lipid bilayers between glass plates so that the bilayer normal makes an angle of 90 deg. (or of the magic angle) with B{sub 0}. We have measured T{sub 2}s, CSAs, and linewidths for the choline {sup 13}C-{gamma}-methyl, the cholesterol-C{sub 4} carbons and the lipid head group phosphorus, at both angles and 313 K. The magnetic field distribution within the sample was calculated using the surface current formalism. The line shapes were simulated as a function of B{sub 0} field inhomogeneities and sample mosaic spread. Both effects contribute to the experimental linewidth. Using three signals of different CSA, we have quantified both contributions and measured the mosaic spread accurately. Direct shimming on a sample signal is essential to obtain sharp resonances and {sup 13}C labelled choline methyl resonance of DMPC is a good candidate for this task. After optimisation of the important parameters (shimming on the choline resonance, mosaic spread of {+-} 0.30 deg.), {sup 13}C linewidth of 0.2-0.3 ppm have been obtained. This newly achieved resolution on bilayers oriented at 90 deg., has allowed to perform two 2D experiments, with a good sensitivity: 2D PELF (correlation of carbon chemical shifts and C-H dipolar couplings) and 2D D-resolved experiment (correlation of carbon chemical shifts and C-C dipolar couplings). A C-C dipolar coupling of 35 {+-} 2 Hz between the choline methyl carbons was determined.

  16. Site-specific thermodynamic stability and unfolding of a de novo designed protein structural motif mapped by 13C isotopically edited IR spectroscopy.

    Science.gov (United States)

    Kubelka, Ginka S; Kubelka, Jan

    2014-04-23

    The mechanism of protein folding remains poorly understood, in part due to limited experimental information available about partially folded states. Isotopically edited infrared (IR) spectroscopy has emerged as a promising method for studying protein structural changes with site-specific resolution, but its full potential to systematically probe folding at multiple protein sites has not yet been realized. We have used (13)C isotopically edited IR spectroscopy to investigate the site-specific thermal unfolding at seven different locations in the de novo designed helix-turn-helix protein αtα. As one of the few stable helix-turn-helix motifs, αtα is an excellent model for studying the roles of secondary and tertiary interactions in folding. Circular dichroism (CD) experiments on the full αtα motif and its two peptide fragments show that interhelical tertiary contacts are critical for stabilization of the secondary structure. The site-specific thermal unfolding probed by (13)C isotopically edited IR is likewise consistent with primarily tertiary stabilization of the local structure. The least thermally stable part of the αtα motif is near the turn where the interhelical contacts are rather loose, while the motif's center with best established core packing has the highest stability. Similar correlation between the local thermal stability and tertiary contacts was found previously for a naturally occurring helix-turn-helix motif. These results underline the importance of native-like tertiary stabilizing interactions in folding, in agreement with recent state-of-the art folding simulations as well as simplified, native-centric models.

  17. 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

  18. Synthesis and structural analysis of 13C-fatty acids

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The 13C-labeled fatty acids octanoic-1-13C acid and palmitic-l-13C acid were synthetically prepared from Ba 13CO3. The yield of the former was more than 90% and that of the latter was above 85%. MS, IR, 1H-NMR and 13NMR were performed to analyze the structures of the two 13C-fatty acids, compared with their unlabeled fatty acids.

  19. High-resolution NMR spectroscopy under the fume hood.

    Science.gov (United States)

    Küster, Simon K; Danieli, Ernesto; Blümich, Bernhard; Casanova, Federico

    2011-08-01

    This work reports the possibility to acquire high-resolution (1)H NMR spectra with a fist-sized NMR magnet directly installed under the fume hood. The small NMR sensor based on permanent magnets was used to monitor the trimerization of propionaldehyde catalyzed by indium trichloride in real time by continuously circulating the reaction mixture through the magnet bore in a closed loop with the help of a peristaltic pump. Thanks to the chemical selectivity of NMR spectroscopy the progress of the reaction can be monitored on-line by determining the concentrations of both reactant and product from the area under their respective lines in the NMR spectra as a function of time. This in situ measurement demonstrates that NMR probes can be used in chemistry laboratories, e.g. for reaction optimization, or installed at specific points of interest along industrial process lines. Therefore, it will open the door for the implementation of feedback control based on spectroscopic NMR data. PMID:21698335

  20. Dynamics in photosynthetic transient complexes studied by paramagnetic NMR spectroscopy

    NARCIS (Netherlands)

    Scanu, Sandra

    2013-01-01

    This PhD thesis focuses on fundamental aspects of protein-protein interactions. A multidisciplinary methodology for the detection and visualization of transient, lowly-populated encounter protein complexes is described. The new methodology combined paramagnetic NMR spectroscopy with computational me

  1. sup(1)H, sup(13)C and sup(17)O NMR studies of cumene hydroperoxide coordination to Cr(AA)sub(3)

    International Nuclear Information System (INIS)

    The mechanism of the catalytic decomposition of hydroperoxides by tris-chelates of transition metals was studied by means of NMR. It was established that the outer sphere coordination of cumene hydroperoxide to tris-acetylacetonate of Cr(III) (Cr(AA)sub(3)) is due to both the formation of hydrogen bonds between hydroxyl proton and chelate oxygen atoms and the π-π-interactions between the aromatic ring and chelate π-system. (author)

  2. Routine method for quantitative /sup 13/C NMR spectra editing and providing structural patterns. Application to every kind of petroleum fractions including residues and asphaltenes

    Energy Technology Data Exchange (ETDEWEB)

    Bouquet, M.; Bailleul, A.

    1986-09-01

    In order to derive structural hydrocarbon patterns of petroleum cuts, including high molecular fractions and heavy cuts, in both quantitative and routine procedure, the authors have built up a method based on inverse gated decoupling and gated spin-echo /sup 13/C experiments. Multiplet selection methods allow identification of CH/sub n/ groups (n is 0-3) and quantitativeness is obtained with the use of relaxation reagent, two conventional spin echo and three gated spin echo experiments, and a correction factor applied to aliphatic carbons basic spectra. Different steps of the method are discussed theoretically and examples dealing with vacuum distillates, residues and fractions (resins, asphaltenes) are given. Emphasis has been put on the experimental and practical running of the described method, convenient with routine industrial research experiments. 14 references.

  3. Ground-fire effects on the composition of dissolved and total organic matter in forest floor and soil solutions from Scots pine forests in Germany: new insights from solid state 13C NMR analysis

    Science.gov (United States)

    Näthe, Kerstin; Michalzik, Beate; Levia, Delphis; Steffens, Markus

    2016-04-01

    Fires represent an ecosystem disturbance and are recognized to seriously pertubate the nutrient budgets of forested ecosystems. While the effects of fires on chemical, biological, and physical soil properties have been intensively studied, especially in Mediterranean areas and North America, few investigations examined the effects of fire-induced alterations in the water-bound fluxes and the chemical composition of dissolved and particulate organic carbon and nitrogen (DOC, POC, DN, PN). The exclusion of the particulate organic matter fraction (0.45 μm soil solutions (A, B horizon) from Scots pine forests in Germany. In relation to control sites, we test the effects of low-severity fires on: (1) the composition of DOM and TOM in forest floor and soil solutions; and (2) the translocated amount of particulate in relation to DOC and DN into the subsoil. The project aims to uncover the mechanisms of water-bound organic matter transport along an ecosystem profile and its compositional changes following a fire disturbance. Forest floor and soil solutions were fortnightly sampled from March to December 2014 on fire-manipulated and control plots in a Scots pine forest in Central Germany. Shortly after the experimental duff fire in April 2014 pooled solutions samples were taken for solid-state 13C NMR spectroscopy to characterize DOM (filtered solution soil. For TOM, fire effects became notable only in the A horizon, exhibiting a decrease in aromaticity from 22 to 18% compared to the control, due to increased O-alkyl-C and diminished aryl-C proportions. Compared to the control, fire only caused minor DOC release rates (soil, while DN in the FF was significantly mobilized (+ 40%) by fire exhibiting annual values of 33 at the control sites compared to 46 kg DN ha-1 at the fire treated sites. Compared to the control, fire events did not significantly enhance the proportion of POC and PN in the total C and N amounts exhibiting values between 10 and 20%. To fully understand the

  4. Solid state 13C-NMR, infrared, X-ray powder diffraction and differential thermal studies of the homologous series of some mono-valent metal (Li, Na, K, Ag) n-alkanoates: A comparative study

    Science.gov (United States)

    Nelson, Peter N.; Ellis, Henry A.; White, Nicole A. S.

    2015-06-01

    A comparative study of the molecular packing, lattice structures and phase behaviors of the homologous series of some mono-valent metal carboxylates (Li, Na, K and Ag) is carried out via solid state FT-infrared and 13C-NMR spectroscopes, X-rays powder diffraction, density measurements, differential scanning calorimetry, polarizing light microscopy and variable temperature infrared spectroscopy. It is proposed that, for lithium, sodium and potassium carboxylates, metal-carboxyl coordination is via asymmetric chelating bidentate bonding with extensive intermolecular interactions to form tetrahedral metal centers, irrespective of chain length. However, for silver n-alkanoates, carboxyl moieties are bound to silver ions via syn-syn type bridging bidentate coordination to form dimeric units held together by extensive head group inter-molecular interactions. Furthermore, the fully extended hydrocarbon chains which are crystallized in the all-trans conformation are tilted at ca. 30°, 27°, 15° and 31° with respect to a normal to the metal plane, for lithium, sodium, silver and potassium carboxylates, respectively. All compounds are packed as lamellar bilayer structures, however, lithium compounds are crystallized in a triclinic crystal system whilst silver, sodium and potassium n-alkanoates are all monoclinic with possible P1 bravais lattice. Odd-even alternation observed in various physical features is associated with different inter-planar spacing between closely packed layers in the bilayer which are not in the same plane; a phenomenon controlled by lattice packing symmetry requirements. All compounds, except silver carboxylates, show partially reversibly first order pre-melting transitions; the number of which increases with increasing chain length. These transitions are associated, for the most part, with lamellar collapse followed by increased gauche-trans isomerism in the methylene group assembly, irrespective of chain length. It is proposed that the absence of

  5. Recovering Invisible Signals by Two-Field NMR Spectroscopy.

    Science.gov (United States)

    Cousin, Samuel F; Kadeřávek, Pavel; Haddou, Baptiste; Charlier, Cyril; Marquardsen, Thorsten; Tyburn, Jean-Max; Bovier, Pierre-Alain; Engelke, Frank; Maas, Werner; Bodenhausen, Geoffrey; Pelupessy, Philippe; Ferrage, Fabien

    2016-08-16

    Nuclear magnetic resonance (NMR) studies have benefited tremendously from the steady increase in the strength of magnetic fields. Spectacular improvements in both sensitivity and resolution have enabled the investigation of molecular systems of rising complexity. At very high fields, this progress may be jeopardized by line broadening, which is due to chemical exchange or relaxation by chemical shift anisotropy. In this work, we introduce a two-field NMR spectrometer designed for both excitation and observation of nuclear spins in two distinct magnetic fields in a single experiment. NMR spectra of several small molecules as well as a protein were obtained, with two dimensions acquired at vastly different magnetic fields. Resonances of exchanging groups that are broadened beyond recognition at high field can be sharpened to narrow peaks in the low-field dimension. Two-field NMR spectroscopy enables the measurement of chemical shifts at optimal fields and the study of molecular systems that suffer from internal dynamics, and opens new avenues for NMR spectroscopy at very high magnetic fields.

  6. Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine

    Science.gov (United States)

    Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

    2014-09-01

    The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1 and 4000-10 cm-1, respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results.

  7. 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

  8. Ultrafast 2D NMR: An Emerging Tool in Analytical Spectroscopy

    Science.gov (United States)

    Giraudeau, Patrick; Frydman, Lucio

    2014-06-01

    Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago, a so-called ultrafast (UF) approach was proposed, capable of delivering arbitrary 2D NMR spectra involving any kind of homo- or heteronuclear correlation, in a single scan. During the intervening years, the performance of this subsecond 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool experiencing an expanded scope of applications. This review summarizes the principles and main developments that have contributed to the success of this approach and focuses on applications that have been recently demonstrated in various areas of analytical chemistry—from the real-time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications.

  9. Use of NMR spectroscopy in combination with pattern recognition techniques for elucidation of origin and adulteration of foodstuffs

    Energy Technology Data Exchange (ETDEWEB)

    Standal, Inger Beate

    2009-07-01

    Consumers and food authorities are, to an increasing extent, concerned about factors such as the origin of food, how it is produced, and if it is healthy and safe. There are methods for general quality control to map the safety and nutritional value; however there is a need for suitable analytical methods to verify information such as the production method (wild/farmed), geographical origin, species, and process history of foods. This thesis evaluates the applicability of using nuclear magnetic resonance (NMR) spectroscopy combined with pattern recognition techniques for authentication of foodstuffs. Fish and marine oils were chosen as materials. 13C NMR was applied to authenticate marine oils and muscle lipids of both fatty and lean fish, according to production method (wild/farmed), geographical origin, species, and process history. 1H NMR was applied on low molecular weight compounds extracted from cod muscle to authenticate fish according to species and processing conditions. 13C NMR combined with pattern recognition techniques enabled the differentiation of marine oils according to wild/farmed and geographical origin of the raw material. It is suggested that this was mainly due to the different diets of the fish from which the oil was produced. It was also possible to authenticate marine oils according to species, and to say something about the level of mixtures detectable. The Sn-2 position specificity of fatty acids in triacylglycerols was shown to be an important characteristic to separate oils of different species. Esterified fish oil (concentrates) could easily be differentiated from natural fish oil by their 13C NMR profile. (Author)

  10. Advanced Structural Determination of Diterpene Esters Using Molecular Modeling and NMR Spectroscopy.

    Science.gov (United States)

    Nothias-Scaglia, Louis-Félix; Gallard, Jean-François; Dumontet, Vincent; Roussi, Fanny; Costa, Jean; Iorga, Bogdan I; Paolini, Julien; Litaudon, Marc

    2015-10-23

    Three new jatrophane esters (1-3) were isolated from Euphorbia amygdaloides ssp. semiperfoliata, including an unprecedented macrocyclic jatrophane ester bearing a hemiketal substructure, named jatrohemiketal (3). The chemical structures of compounds 1-3 and their relative configurations were determined by spectroscopic analysis. The absolute configuration of compound 3 was determined unambiguously through an original strategy combining NMR spectroscopy and molecular modeling. Conformational search calculations were performed for the four possible diastereomers 3a-3d differing in their C-6 and C-9 stereocenters, and the lowest energy conformer was used as input structure for geometry optimization. The prediction of NMR parameters ((1)H and (13)C chemical shifts and (1)H-(1)H coupling constants) by density functional theory (DFT) calculations allowed identifying the most plausible diastereomer. Finally, the stereostructure of 3 was solved by comparison of the structural features obtained by molecular modeling for 3a-3d with NMR-derived data (the values of dihedral angles deduced from the vicinal proton-proton coupling constants ((3)JHH) and interproton distances determined by ROESY). The methodology described herein provides an efficient way to solve or confirm structural elucidation of new macrocyclic diterpene esters, in particular when no crystal structure is available.

  11. Novel monosaccharide fermentation products in Caldicellulosiruptor saccharolyticus identified using NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Isern, Nancy G.; Xue, Junfeng; Rao, Jaya V.; Cort, John R.; Ahring, Birgitte K.

    2013-04-03

    Profiles of metabolites produced by the thermophilic obligately anaerobic cellulose-degrading Gram-positive bacterium Caldicellulosiruptor saccharolyticus DSM 8903 strain following growth on different monosaccharides (D-glucose, D-mannose, L-arabinose, D-arabinose, D-xylose, L-fucose, and D-fucose) as carbon sources revealed several unexpected fermentation products, suggesting novel metabolic capacities and unexplored metabolic pathways in this organism. Both 1H and 13C nuclear magnetic resonance (NMR) spectroscopy were used to determine intracellular and extracellular metabolite profiles. Metabolite profiles were determined from 1-D 1H NMR spectra by curve fitting against spectral libraries provided in Chenomx software. To reduce uncertainties due to unassigned, overlapping, or poorly-resolved peaks, metabolite identifications were confirmed with 2-D homonuclear and heteronuclear NMR experiments. In addition to expected metabolites such as acetate, lactate, glycerol, and ethanol, several novel fermentation products were identified: ethylene glycol (from growth on D-arabinose, though not L-arabinose), acetoin and 2,3-butanediol (from D-glucose and L-arabinose), and hydroxyacetone (from D-mannose and L-arabinose). Production of ethylene glycol from D-arabinose was particularly notable, with around 10% of the substrate carbon converted into this uncommon fermentation product. The novel products have not previously been reported to be produced by C. saccharolyticus, nor would they be easily predicted from the current genome annotation, and show new potentials for using this strain for production of bioproducts.

  12. Structural Characterization of Lignins Isolated from Caragana sinica Using FT-IR and NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    XIAOLing-ping; SHIZheng-jun; XUFeng; SUN Run-cang; Amar Kmohanty

    2011-01-01

    In order to efficiently explore and use woody biomass,six lignin fractions were isolated from dewaxed Caragana sinica via successive extraction with organic.solvents and alkaline solutions.The lignin structures were characterized by Fourier transform infrared spectroscopy (FT-IR) and 1D and 2D Nuclear Magnetic Resonance (NMR).FT-IR spectra revealed that the “core” of the lignin structure did not significantly change during the treatment under the conditions given.The results of 1 H and 13C NMR demonstrated that the lignin fraction L2,isolated with 70% ethanol containing 1% NaOH,was mainly composed of β-O-4 ether bonds together with G and S units and trace p-hydroxyphenyl unit.Based on the 2D HSQC NMR spectrum,the ethanol organosolv lignin fraction L1,extracted with 70% ethanol,presents a predominance of β-O-4' arylether linkages (61% of total side chains),and a low abundance of condensed carbon-carbon linked structures (such as β-β',β-1',and β-5') and a lower S/G ratio.Furthermore,a small percentage (ca.9%) of the linkage side chain was found to be acylated at the γ-carbon.

  13. Study of aging in oil paintings by 1D and 2D NMR spectroscopy.

    Science.gov (United States)

    Spyros, Apostolos; Anglos, Demetrios

    2004-09-01

    Nuclear magnetic resonance spectroscopy is proposed as an efficient analytical tool in the study of painted artworks. The binding medium from two original oil paintings, dated from the early 20th and the late 17th century, was studied via high-resolution 1D and 2D NMR, establishing the advanced state of hydrolysis and oxidation of the oil paint. Studies of the solvent-extractable component from model samples of various drying oils, raw oil paints, and aged oil paints allowed the definition of several markers based on the integral ratios of various chemical species present in the 1H and 13C NMR spectra. These markers are sensitive to hydrolytic and oxidative processes that reflect the extent of aging in oil paintings. The rapidity, simplicity, and nondestructive nature of the proposed analytical NMR methodology represents a great advantage, since the usually minute sample quantities available from original artwork can be subsequently analyzed further by other analytical techniques, if necessary. PMID:15373425

  14. Structural characterization of homogalacturonan by NMR spectroscopy - assignment of reference compounds

    DEFF Research Database (Denmark)

    Petersen, Bent O.; Meier, Sebastian; Duus, Jens Øllgaard;

    2008-01-01

    Complete assignment of 1H and 13C NMR of six hexagalactopyranuronic acids with varying degree and pattern of methyl esterification is reported. The NMR experiments were run at room temperature using approximately 2 mg of sample making this method convenient for studying the structure of homogalac...

  15. Synthesis and applications of {sup 13}C glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Stocking, E.; Khalsa, O.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States)

    1994-12-01

    Due in part to the use of labeled glycerol for the {sup 13}C enrichment of biomolecules, we are currently developing new synthetic routes to various isotopomers of glycerol. Judging from our experience, traditional methods of glycerol synthesis are not easily adapted for isotopic enrichment and/or have poor overall yields (12 to 15%). Furthermore, the use of glycerol for enrichment can be prohibitively expensive and its availability is limited by the level of demand. We are presently developing a short de novo synthesis of glycerol from carbon dioxide ({approximately}53% overall yield for four steps) and are examining the feasibility of synthesizing site-specific {sup 13}C-labeled glycerol and dihydroxyacetone (DHA) from labeled methanol and carbon dioxide. One application of {sup 13}C glycerol we have examined is enzymatic conversion of glycerol to glyceraldehyde-3-monophosphate or dihydroxyacetone monophosphate (DHAP) with yields ranging from 25 to 50% (as determined by NMR spectroscopy). We are also pursuing the chemical conversion of {sup 13}C-labeled DHA to DHAP. We are especially interested in {sup 13}C-labeled DHAP because we are investigating its use as a chemo-enzymatic precursor for both labeled 2-deoxyribose and 2-deoxyribonucleic acids.

  16. Backbone and Ile-δ1, Leu, Val Methyl 1H, 13C and 15N NMR chemical shift assignments for human interferon-stimulated gene 15 protein

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Cuifeng; Aramini, James M.; Ma, LiChung; Cort, John R.; Swapna, G.V.T.; Krug, R. M.; Montelione, Gaetano

    2011-10-01

    Human interferon-stimulated gene 15 protein (ISG15), also called ubiquitin cross-reactive protein (UCRP), is the first identified ubiquitin-like protein containing two ubiquitin-like domains fused in tandem. The active form of ISG15 is conjugated to target proteins via the C-terminal glycine residue through an isopeptide bond in a manner similar to ubiquitin. The biological role of ISG15 is strongly associated with the modulation of cell immune function, and there is mounting evidence suggesting that many viral pathogens evade the host innate immune response by interfering with ISG15 conjugation to both host and viral proteins in a variety of ways. Here we report nearly complete backbone 1HN, 15N, 13CO, and 13Ca, as well as side chain 13Cb, methyl (Ile-d1, Leu, Val), amide (Asn, Gln), and indole NH (Trp) NMR resonance assignments for the 157-residue human ISG15 protein. These resonance assignments provide the basis for future structural and functional solution NMR studies of the biologically important human ISG15 protein.

  17. Mobile sensor for high resolution NMR spectroscopy and imaging

    Science.gov (United States)

    Danieli, Ernesto; Mauler, Jörg; Perlo, Juan; Blümich, Bernhard; Casanova, Federico

    2009-05-01

    In this work we describe the construction of a mobile NMR tomograph with a highly homogeneous magnetic field. Fast MRI techniques as well as NMR spectroscopy measurements were carried out. The magnet is based on a Halbach array built from identical permanent magnet blocks generating a magnetic field of 0.22 T. To shim the field inhomogeneities inherent to magnet arrays constructed from these materials, a shim strategy based on the use of movable magnet blocks is employed. With this approach a reduction of the line-width from ˜20 kHz to less than 0.1 kHz was achieved, that is by more than two orders of magnitude, in a volume of 21 cm 3. Implementing a RARE sequence, 3D images of different objects placed in this volume were obtained in short experimental times. Moreover, by reducing the sample size to 1 cm 3, sub ppm resolution is obtained in 1H NMR spectra.

  18. Synthesis of Gemcitabine-13C, 15N2 and Gemcitabine-13C, 15N2 Metabolites

    Directory of Open Access Journals (Sweden)

    ZHU Cheng-gu;YANG Shao-zu;YAN Sheng-wang;FANG Ning-jing;CAI Ding-long;LI Gang

    2014-02-01

    Full Text Available Homemade urea-13C, 15N2 was used to react with 3-methyl acrylonitrile closure to form cytosine-13C, 15N2 (2,which was protected by trimethylsilylation with BSA and condensed with 2-deoxy-2,2-difluoro-D-erythro-pentofuranose-3,5-dibenzoate-1-methanesulfonate at 120 ℃ to afford blocked gemcitabine-13C, 15N2. Hydrolytic removal of the blocking groups of gemcitabine-13C, 15N2 with NaOH gave gemcitabine-13C, 15N2, and its metabolite was obtained by further hydrolytic deamination of gemcitabine-13C, 15N2. The final products were characterized and detected by HPLC, LC-MS and NMR, and confirmed that the chemical purities were higher than 98%, isotopic abundances were 99% 13C, 98% 15N, and they were suitable for drug metabolism studies.

  19. Multi-Spectroscopic Analysis of Seed Quality and 13C-Stable-Iotopologue Monitoring in Initial Growth Metabolism of Jatropha curcas L.

    Directory of Open Access Journals (Sweden)

    Takanori Komatsu

    2014-11-01

    Full Text Available In the present study, we applied nuclear magnetic resonance (NMR, as well as near-infrared (NIR spectroscopy, to Jatropha curcas to fulfill two objectives: (1 to qualitatively examine the seeds stored at different conditions, and (2 to monitor the metabolism of J. curcas during its initial growth stage under stable-isotope-labeling condition (until 15 days after seeding. NIR spectra could non-invasively distinguish differences in storage conditions. NMR metabolic analysis of water-soluble metabolites identified sucrose and raffinose family oligosaccharides as positive markers and gluconic acid as a negative marker of seed germination. Isotopic labeling patteren of metabolites in germinated seedlings cultured in agar-plate containg 13C-glucose and 15N-nitrate was analyzed by zero-quantum-filtered-total correlation spectroscopy (ZQF-TOCSY and 13C-detected 1H-13C heteronuclear correlation spectroscopy (HETCOR. 13C-detected HETOCR with 13C-optimized cryogenic probe provided high-resolution 13C-NMR spectra of each metabolite in molecular crowd. The 13C-13C/12C bondmer estimated from 1H-13C HETCOR spectra indicated that glutamine and arginine were the major organic compounds for nitrogen and carbon transfer from roots to leaves.

  20. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    Science.gov (United States)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  1. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  2. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  3. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    International Nuclear Information System (INIS)

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens

  4. A Large Scale Separation of Taxanes from the Bark Extract of Taxus yunnanesis and 1H- and 13C-NMR Assignments for 7-epi-10-Deacetyltaxol

    Institute of Scientific and Technical Information of China (English)

    薛军; 卜海山; 曹春阳; 吴厚铭; 陈建民

    2001-01-01

    A large-scale separation of paclitaxel from semi-purified bark extract of Taxus yunnanesis was investigated. The chromatographic behavior of paclitaxel and two close eluting analogues, cephalomannine and 7-epi-10-deacetyltaxol were sytematically studied on a C18 bonded phase column with different mobile phase in reverse phase mode. According to the notably different selectivity of the methanol and acetonitrile with water in the mobile phase and the most important requirement of capacity in preparative chromatography, the optimum suitably mobile phase used in a large-scale isolation of paclitaxel and 7-epi-10-deacetyltaxol on a preparative C18 column was given.Cephalomannine was eliminated by ozonolysis and after then separated throughout a normal phase silica column.The whole large-scale process for high purity paclitaxel from the bark extract of Taxus yunnanesis consisted of a preliminary purification with Biotage FLASH 150i systen based on a prepacked normal phase silica cartridge followed by using a C18 Nova-pakTM column in Waters PrepLCTM 4000 prepparative HPLC system. The structure of 7-epi-10-deacetyltaxol was elucidated by 2O NMR technologies of TOCSY, DQF-COSY,HMQC and HMBC, etc.

  5. Spectroscopic characteristic (FT-IR, FT-Raman, UV, 1H and 13C NMR), theoretical calculations and biological activity of alkali metal homovanillates

    Science.gov (United States)

    Samsonowicz, M.; Kowczyk-Sadowy, M.; Piekut, J.; Regulska, E.; Lewandowski, W.

    2016-04-01

    The structural and vibrational properties of lithium, sodium, potassium, rubidium and cesium homovanillates were investigated in this paper. Supplementary molecular spectroscopic methods such as: FT-IR, FT-Raman in the solid phase, UV and NMR were applied. The geometrical parameters and energies were obtained from density functional theory (DFT) B3LYP method with 6-311++G** basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned. Geometric and magnetic aromaticity indices, atomic charges, dipole moments, HOMO and LUMO energies were also calculated. The microbial activity of investigated compounds was tested against Bacillus subtilis (BS), Pseudomonas aeruginosa (PA), Escherichia coli (EC), Staphylococcus aureus (SA) and Candida albicans (CA). The relationship between the molecular structure of tested compounds and their antimicrobial activity was studied. The principal component analysis (PCA) was applied in order to attempt to distinguish the biological activities of these compounds according to selected band wavenumbers. Obtained data show that the FT-IR spectra can be a rapid and reliable analytical tool and a good source of information for the quantitative analysis of the relationship between the molecular structure of the compound and its biological activity.

  6. Two-dimensional NMR spectroscopy strongly enhances soil organic matter composition analysis

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Hedenström, Mattias; Schleucher, Jürgen

    2016-04-01

    Soil organic matter (SOM) is the largest terrestrial carbon pool and strongly affects soil properties. With climate change, understanding SOM processes and turnover and how they could be affected by increasing temperatures becomes critical. This is particularly key for organic soils as they represent a huge carbon pool in very sensitive ecosystems, like boreal ecosystems and peatlands. Nevertheless, characterization of SOM molecular composition, which is essential to elucidate soil carbon processes, is not easily achieved, and further advancements in that area are greatly needed. Solid-state one-dimensional (1D) 13C nuclear magnetic resonance (NMR) spectroscopy is often used to characterize its molecular composition, but only provides data on a few major functional groups, which regroup many different molecular fragments. For instance, in the carbohydrates region, signals of all monosaccharides present in many different polymers overlap. This overlap thwarts attempts to identify molecular moieties, resulting in insufficient information to characterize SOM composition. Here we show that two-dimensional (2D) liquid-state 1H-13C NMR spectra provided much richer data on the composition of boreal plant litter and organic surface soil. The 2D spectra indeed resolved overlaps observed in 1D 13C spectra and displayed signals from hundreds of identifiable molecular groups. For example, in the aromatics region, signals from individual lignin units could be recognized. It was hence possible to follow the fate of specific structural moieties in soils. We observed differences between litter and soil samples, and were able to relate them to the decomposition of identifiable moieties. Sample preparation and data acquisition were both simple and fast. Further, using multivariate data analysis, we aimed at linking the detailed chemical fingerprints of SOM to turnover rates in a soil incubation experiment. With the multivariate models, we were able to identify specific molecular

  7. Degradation of mangrove tissues by arboreal termites (Nasutitermes acajutlae) and their role in the mangrove C cycle (Puerto Rico): Chemical characterization and organic matter provenance using bulk δ13C, C/N, alkaline CuO oxidation-GC/MS, and solid-state 13C NMR

    Science.gov (United States)

    Vane, Christopher H.; Kim, Alexander W.; Moss-Hayes, Vicky; Snape, Colin E.; Diaz, Miguel Castro; Khan, Nicole S.; Engelhart, Simon E.; Horton, Benjamin P.

    2013-08-01

    Arboreal termites are wood decaying organisms that play an important role in the first stages of C cycling in mangrove systems. The chemical composition of Rhizophora mangle, Avicennia germinans, and Laguncularia racemosa leaf, stem, and pneumatophore tissues as well as associated sediments was compared to that of nests of the termite Nasutitermes acajutlae. Nests gave δ13C values of -26.1 to -27.2‰ (±0.1) and C/N of 43.3 (±2.0) to 98.6 (±16.2) which were similar to all stem and pneumatophores but distinct from mangrove leaves or sediments. Organic matter processed by termites yielded lignin phenol concentrations (Λ, lambda) that were 2-4 times higher than stem or pneumatophores and 10-20 times higher than that of leaves or sediments, suggesting that the nests were more resistant to biodegradation than the mangrove vegetation source. 13C NMR revealed that polysaccharide content of mangrove tissues (50-69% C) was higher than that of the nests (46-51% C). Conversely, lignin accounted for 16.2-19.6% C of nest material, a threefold increase relative to living mangrove tissues; a similar increase in aromatic methoxyl content was also observed in the nests. Lipids (aliphatic and paraffinic moieties) were also important but rather variable chemical components of all three mangrove species, representing between 13.5 and 28.3% of the C content. Termite nests contained 3.14 Mg C ha-1 which represents approximately 2% of above ground C storage in mangroves, a value that is likely to increase upon burial due to their refractory chemical composition.

  8. A study of conformational stability of poly(L-alanine), poly(L-valine), and poly(L-alanine)/poly(L-valine) blends in the solid state by (13)C cross-polarization/magic angle spinning NMR.

    Science.gov (United States)

    Murata, Katsuyoshi; Kuroki, Shigeki; Kimura, Hideaki; Ando, Isao

    2002-06-01

    13C cross-polarization/magic angle spinning (CP/MAS) NMR and (1)H T(1rho) experiments of poly(L-alanine) (PLA), poly(L-valine) (PLV), and PLA/PLV blends have been carried out in order to elucidate the conformational stability of the polypeptides in the solid state. These were prepared by adding a trifluoroacetic acid (TFA) solution of the polymer with a 2.0 wt/wt % of sulfuric acid (H(2)SO(4)) to alkaline water. From these experimental results, it is clarified that the conformations of PLA and PLV in their blends are strongly influenced by intermolecular hydrogen-bonding interactions that cause their miscibility at the molecular level. PMID:11948439

  9. 13C Magic angle spinning NMR analysis and quantum chemical modeling of the bathochromic shift of astaxanthin in alpha-crustacyanin, the blue carotenoprotein complex in the carapace of the lobster Homarus gammarus.

    Science.gov (United States)

    Weesie, R J; Jansen, F J; Merlin, J C; Lugtenburg, J; Britton, G; de Groot, H J

    1997-06-17

    Selective isotope enrichment, 13C magic angle spinning (MAS) NMR, and semiempirical quantum chemical modeling, have been used to analyze ligand-protein interactions associated with the bathochromic shift of astaxanthin in alpha-crustacyanin, the blue carotenoprotein complex from the carapace of the lobster Homarus gammarus. Spectra of alpha-crustacyanin were obtained after reconstitution with astaxanthins labeled with 13C at positions 4,4', 12,12', 13,13', or 20,20'. The data reveal substantial downfield shifts of 4.9 and 7.0 ppm at positions 12 and 12' in the complex, respectively. In contrast, at the 13 and 13' positions, small upfield shifts of 1.9 ppm were observed upon binding to the protein. These data are in line with previously obtained results for positions 14,14' (3.9 and 6.8 ppm downfield) and 15,15' (0.6 ppm upfield) and confirm the unequal perturbation of both halves after binding of the chromophore. However, these results also show that the main perturbation is of symmetrical origin, since the chemical shift differences exhibit a similar pattern in both halves of the astaxanthin molecule. A small downfield shift of 2.4 ppm was detected for the 4 and 4' positions. Finally, the 20,20' methyl groups are shifted 0.4 ppm upfield by the protein. The full data set provides convincing evidence that charge polarization is of importance for the bathochromic shift. The NMR shifts are compared with calculated charge densities for astaxanthin subjected to variations in protonation states of the ring-functional groups, as models of ligand-protein interactions. Taking into account the color shift and other available optical data, the current model for the mechanisms of interaction with the protein was refined. The results point toward a mechanism in which the astaxanthin is charged and subject to strong electrostatic polarizations originating from both keto groups, most likely a double protonation. PMID:9200677

  10. Structural investigation of aluminium doped ZnO nanoparticles by solid-state NMR spectroscopy.

    Science.gov (United States)

    Avadhut, Yamini S; Weber, Johannes; Hammarberg, Elin; Feldmann, Claus; Schmedt auf der Günne, Jörn

    2012-09-01

    The electrical conductivity of aluminium doped zinc oxide (AZO, ZnO:Al) materials depends on doping induced defects and grain structure. This study aims at relating macroscopic electrical conductivity of AZO nanoparticles with their atomic structure, which is non-trivial because the derived materials are heavily disordered and heterogeneous in nature. For this purpose we synthesized AZO nanoparticles with different doping levels and narrow size distribution by a microwave assisted polyol method followed by drying and a reductive treatment with forming gas. From these particles electrically conductive, optically transparent films were obtained by spin-coating. Characterization involved energy-dispersive X-ray analysis, wet chemical analysis, X-ray diffraction, electron microscopy and dynamic light scattering, which provided a basis for a detailed structural solid-state NMR study. A multinuclear ((27)Al, (13)C, (1)H) spectroscopic investigation required a number of 1D MAS NMR and 2D MAS NMR techniques (T(1)-measurements, (27)Al-MQMAS, (27)Al-(1)H 2D-PRESTO-III heteronuclear correlation spectroscopy), which were corroborated by quantum chemical calculations with an embedded cluster method (EEIM) at the DFT level. From the combined data we conclude that only a small part of the provided Al is incorporated into the ZnO structure by substitution of Zn. The related (27)Al NMR signal undergoes a Knight shift when the material is subjected to a reductive treatment with forming gas. At higher (formal) doping levels Al forms insulating (Al, H and C containing) side-phases, which cover the surface of the ZnO:Al particles and increase the sheet resistivity of spin-coated material. Moreover, calculated (27)Al quadrupole coupling constants serve as a spectroscopic fingerprint by which previously suggested point-defects can be identified and in their great majority be ruled out. PMID:22801707

  11. Advancements in waste water characterization through NMR spectroscopy: review.

    Science.gov (United States)

    Alves Filho, Elenilson G; Alexandre e Silva, Lorena M; Ferreira, Antonio G

    2015-09-01

    There are numerous organic pollutants that lead to several types of ecosystem damage and threaten human health. Wastewater treatment plants are responsible for the removal of natural and anthropogenic pollutants from the sewage, and because of this function, they play an important role in the protection of human health and the environment. Nuclear magnetic resonance (NMR) has proven to be a valuable analytical tool as a result of its versatility in characterizing both overall chemical composition as well as individual species in a wide range of mixtures. In addition, NMR can provide physical information (rigidity, dynamics, etc.) as well as permit in depth quantification. Hyphenation with other techniques such as liquid chromatography, solid phase extraction and mass spectrometry creates unprecedented capabilities for the identification of novel and unknown chemical species. Thus, NMR is widely used in the study of different components of wastewater, such as complex organic matter (fulvic and humic acids), sludge and wastewater. This review article summarizes the NMR spectroscopy methods applied in studies of organic pollutants from wastewater to provide an exhaustive review of the literature as well as a guide for readers interested in this topic. PMID:25280056

  12. NMR spectroscopy of proteins encapsulated in a positively charged surfactant.

    Science.gov (United States)

    Lefebvre, Brian G; Liu, Weixia; Peterson, Ronald W; Valentine, Kathleen G; Wand, A Joshua

    2005-07-01

    Traditionally, large proteins, aggregation-prone proteins, and membrane proteins have been difficult to examine by modern multinuclear and multidimensional solution NMR spectroscopy. A major limitation presented by these protein systems is that their slow molecular reorientation compromises many aspects of the more powerful solution NMR methods. Several approaches have emerged to deal with the various spectroscopic difficulties arising from slow molecular reorientation. One of these takes the approach of actively seeking to increase the effective rate of molecular reorientation by encapsulating the protein of interest within the protective shell of a reverse micelle and dissolving the resulting particle in a low viscosity fluid. Since the encapsulation is largely driven by electrostatic interactions, the preparation of samples of acidic proteins suitable for NMR spectroscopy has been problematic owing to the paucity of suitable cationic surfactants. Here, it is shown that the cationic surfactant CTAB may be used to prepare samples of encapsulated anionic proteins dissolved in low viscosity solvents. In a more subtle application, it is further shown that this surfactant can be employed to encapsulate a highly basic protein, which is completely denatured upon encapsulation using an anionic surfactant. PMID:15949753

  13. On-site analysis of d13C- and dD-CH4 by laser spectroscopy for the allocation of source processes

    Science.gov (United States)

    Eyer, Simon; Tuzson, Béla; Popa, Elena; van der Veen, Carina; Röckmann, Thomas; Brand, Willi A.; Fisher, Rebecca; Lowry, David; Nisbet, Euan G.; Brennwald, Matthias S.; Harris, Eliza; Emmenegger, Lukas; Fischer, Hubertus; Mohn, Joachim

    2015-04-01

    Analysis of the most abundant methane isotopologues 12CH4, 13CH4 and 12CH3D can be used to disentangle source/sink processes (Fischer et al. 2008) and to develop target oriented reduction strategies. Isotopic analysis of CH4 is accomplished by isotope-ratio mass-spectrometry (IRMS) and more recently by mid-infrared laser spectroscopy. For high precision measurements in ambient air, however, both techniques rely on preconcentration of the target gas (Eyer et al. 2014). We developed a field-deployable analyser for real-time, on-site analysis of CH4 isotopologues which is based on a dual quantum cascade laser absorption spectrometer (QCLAS) in combination with an innovative preconcentration technique named trace gas extractor (TREX). The core part of the 19 ″ rack-mounted preconcentration unit is a highly efficient adsorbent trap attached to the cold end of a Stirling cooler. The system achieves preconcentration factors >500. For fast desorption and optimal heat management, the trap is decoupled from the cooler during desorption. The QCLAS has been developed based on a previously described instrument (Tuzson 2010). It comprises two cw-QC laser sources combined and coupled into an astigmatic multipass absorption cell with 76 m optical path. The developed technique reaches an unsurpassed precision of 0.1‰ for d13C-CH4 and Behrens, M., Bock, M., Richter, U., Schmitt, J., Loulergue, L., Chappellaz, J., Spahni, R., Blunier, T., Leuenberger, M., Stocker, T. F. (2008) Nature 452: 864-867. Eyer, S., Stadie, N. P., Borgschulte. A., Emmenegger, L., Mohn, J. (2014) Adsorption 20:657-666. Tuzson, B., Hiller, R. V., Zeyer, K., Eugster, W., Neftel, A., Ammann, C., Emmenegger, L. (2010) Atmospheric Measurement Techniques: 1519-1531.

  14. 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.

  15. Microstructure determination of 2-hydroxy ethyl methacrylate and methyl acrylate copolymers by NMR spectroscopy

    Science.gov (United States)

    Brar, A. S.; Hooda, Sunita; Goyal, Ashok Kumar

    2007-02-01

    Copolymers of 2-Hydroxy ethyl methacrylate and methyl acrylate (H/M) of different compositions were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator under nitrogen atmosphere. The copolymers compositions were calculated from 1H NMR spectra. The reactivity ratios for H/M copolymers obtained from a linear Kelen-Tudos method (KT) and nonlinear error-in-variables method (EVM) are rH = 3.31 ± 0.08, rM = 0.23 ± 0.00 and rH = 3.32, rM = 0.23, respectively. The complete spectral assignment of methine, methylene, methyl and carbonyl carbon regions in terms of compositional and configurational sequences of H/M copolymers was done with the help of 13C{ 1H} NMR, distortionless enhancement by polarization transfer (DEPT), two-dimensional heteronuclear single quantum coherence (HSQC) along with total correlated spectroscopy (TOCSY). Further, the assignments of carbonyl region were made with the help of heteronuclear multiple bond coherence (HMBC) spectrum.

  16. Multinuclear NMR spectroscopy for differentiation of molecular configurations and solvent properties between acetone and dimethyl sulfoxide

    Science.gov (United States)

    Wen, Yuan-Chun; Kuo, Hsiao-Ching; Jia, Hsi-Wei

    2016-04-01

    The differences in molecular configuration and solvent properties between acetone and dimethyl sulfoxide (DMSO) were investigated using the developed technique of 1H, 13C, 17O, and 1H self-diffusion liquid state nuclear magnetic resonance (NMR) spectroscopy. Acetone and DMSO samples in the forms of pure solution, ionic salt-added solution were used to deduce their active sites, relative dipole moments, dielectric constants, and charge separations. The NMR results suggest that acetone is a trigonal planar molecule with a polarized carbonyl double bond, whereas DMSO is a trigonal pyramidal-like molecule with a highly polarized S-O single bond. Both molecules use their oxygen atoms as the active sites to interact other molecules. These different molecular models explain the differences their physical and chemical properties between the two molecules and explain why DMSO is classified as an aprotic but highly dipolar solvent. The results are also in agreement with data obtained using X-ray diffraction, neutron diffraction, and theoretical calculations.

  17. Model-free estimation of the effective correlation time for C–H bond reorientation in amphiphilic bilayers: {sup 1}H–{sup 13}C solid-state NMR and MD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Tiago Mendes, E-mail: tiago.ferreira@fkem1.lu.se [Department Chemie, Universität Paderborn, Warburger Straße 100, 33098 Paderborn (Germany); Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Ollila, O. H. Samuli [Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Helsinki Biophysics and Biomembrane Group, Department of Biomedical Engineering and Computational Science, Aalto University, Espoo (Finland); Pigliapochi, Roberta [Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden); Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Dabkowska, Aleksandra P.; Topgaard, Daniel [Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden)

    2015-01-28

    Molecular dynamics (MD) simulations give atomically detailed information on structure and dynamics in amphiphilic bilayer systems on timescales up to about 1 μs. The reorientational dynamics of the C–H bonds is conventionally verified by measurements of {sup 13}C or {sup 2}H nuclear magnetic resonance (NMR) longitudinal relaxation rates R{sub 1}, which are more sensitive to motional processes with correlation times close to the inverse Larmor frequency, typically around 1-10 ns on standard NMR instrumentation, and are thus less sensitive to the 10-1000 ns timescale motion that can be observed in the MD simulations. We propose an experimental procedure for atomically resolved model-free estimation of the C–H bond effective reorientational correlation time τ{sub e}, which includes contributions from the entire range of all-atom MD timescales and that can be calculated directly from the MD trajectories. The approach is based on measurements of {sup 13}C R{sub 1} and R{sub 1ρ} relaxation rates, as well as {sup 1}H−{sup 13}C dipolar couplings, and is applicable to anisotropic liquid crystalline lipid or surfactant systems using a conventional solid-state NMR spectrometer and samples with natural isotopic composition. The procedure is demonstrated on a fully hydrated lamellar phase of 1-palmitoyl-2-oleoyl-phosphatidylcholine, yielding values of τ{sub e} from 0.1 ns for the methyl groups in the choline moiety and at the end of the acyl chains to 3 ns for the g{sub 1} methylene group of the glycerol backbone. MD simulations performed with a widely used united-atom force-field reproduce the τ{sub e}-profile of the major part of the acyl chains but underestimate the dynamics of the glycerol backbone and adjacent molecular segments. The measurement of experimental τ{sub e}-profiles can be used to study subtle effects on C–H bond reorientational motions in anisotropic liquid crystals, as well as to validate the C–H bond reorientation dynamics predicted in MD

  18. 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)

    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 1H 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 2H and 13C 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

  19. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoaceticum metabolic profiles

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Junfeng; Isern, Nancy G.; Ewing, R James; Liyu, Andrey V.; Sears, Jesse A.; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R.; Ahring, Birgitte K.; Majors, Paul D.

    2014-06-20

    An in-situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch-growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution, high sensitivity NMR (HR-NMR) spectroscopy. In-situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at an NMR frequency of 500 MHz, and aliquots of the bioreactor contents were taken for 600 MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in-situ NMR bioreactor facilitated monitoring of the fermentation process in real time, enabling identification of intermediate and end-point metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with the HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.

  20. NMR studies of metalloproteins.

    Science.gov (United States)

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has long been used as an invaluable tool for structure and dynamic studies of macromolecules. Here we focus on the application of NMR spectroscopy in characterization of metalloproteins, including structural studies and identification of metal coordination spheres by hetero-/homo-nuclear metal NMR spectroscopy. Paramagnetic NMR as well as (13)C directly detected protonless NMR spectroscopy will also be addressed for application to paramagnetic metalloproteins. Moreover, these techniques offer great potential for studies of other non-metal binding macromolecules.

  1. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.

    Science.gov (United States)

    Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D

    2014-10-01

    An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.

  2. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.

    Science.gov (United States)

    Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D

    2014-10-01

    An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts. PMID:24946863

  3. {sup 2}H NMR and {sup 13}C-IRMS analyses of acetic acid from vinegar, {sup 18}O-IRMS analysis of water in vinegar: International collaborative study report

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Freddy [Eurofins Scientific Analytics, BP42301, 44323 Nantes (France); Jamin, Eric, E-mail: ericjamin@eurofins.com [Eurofins Scientific Analytics, BP42301, 44323 Nantes (France)

    2009-09-01

    An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the {sup 2}H/{sup 1}H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the {sup 13}C/{sup 12}C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the {sup 18}O/{sup 16}O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations. The precision parameters of the method for measuring {delta}{sup 13}C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 per mille , and the average reproducibility (R) was 0.91 per mille . As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the {sup 2}H/{sup 1}H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources ({delta}{sup 13}C and {delta}{sup 18}O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring {delta}{sup 18}O were found to be similar

  4. Report on neptunium speciation by NMR and optical spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Tait, C.D.; Palmer, P.D.; Ekberg, S.A.; Clark, D.L.

    1995-11-01

    Hydrolysis and carbonate complexation reactions were examined for NpO{sub 2}{sup 2+} and NpO{sub 2}{sup +} ions by a variety of techniques including potentiometric titration, UV-Vis-NIR and NMR spectroscopy. The equilibrium constant for the reaction 3NpO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} + 3H{sup +} {rightleftharpoons} (NpO{sub 2}){sub 3}(CO{sub 3}){sub 6}{sup 6{minus}} + 3HCO{sub 3}{sup {minus}} was determined to be logK = 19.7 ({plus_minus} 0.8) (I = 2.5 m). {sup 17}O NMR spectroscopy of NpO{sub 2}{sup n+} ions (n = 1,2) reveals a readily observable {sup 17}O resonance for n = 2, but not for n = 1. The first hydrolysis constant for NpO{sub 2}{sup +} was studied as a function of temperature, and the functional form for the temperature-dependent equilibrium constant for the reaction written as NpO{sub 2}{sup +} + H{sub 2}O {rightleftharpoons} NpO{sub 2}OH + H{sup +} was found to be logK = 2.28 {minus} 3780/T, where T is in {degree}K. Finally, the temperature dependence of neptunium(V) carbonate complexation constants was studied. For the first carbonate complexation constant, the appropriate functional form was found to be log{beta}{sub 01} = 1.47 + 786/T.

  5. 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)

  6. Rovibrational constants of the ground state and v8 = 1 state of 13C2HD3 by high-resolution FTIR spectroscopy

    Science.gov (United States)

    Ng, L. L.; Tan, T. L.

    2016-06-01

    The Fourier transform infrared (FTIR) spectrum of the c-type ν8 band of 13C2HD3 was recorded for the first time at a unapodized resolution of 0.0063 cm-1 in the wavenumber region of 830-1000 cm-1. Through the fitting of a total of 1057 assigned infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation, rovibrational constants for the upper state (v8 = 1) up to five quartic centrifugal distortion terms were derived for the first time with a root-mean-square (rms) deviation of 0.00073 cm-1. The band center of ν8 of 13C2HD3 was found to be 913.011021(55) cm-1. Ground state rovibrational constants up to five quartic terms of 13C2HD3 were also determined from a fit of 453 ground state combination-differences from the present infrared measurements with an rms deviation of 0.00072 cm-1 for the first time. The uncertainty of the measured infrared lines was estimated to be ±0.0012 cm-1. From the ground state rotational constants, the inertial defect of 13C2HD3 was calculated to be 0.06973(16) uÅ2, showing the high planarity of the molecule.

  7. Analysis of mercerization process based on the intensity change of deconvoluted resonances of {sup 13}C CP/MAS NMR: Cellulose mercerized under cooling and non-cooling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Kento [Mitsubishi Rayon Co., Ltd. Otake Research Laboratories (Japan); Nakano, Takato, E-mail: tnakano@kais.kyoto-u.ac.jp [Laboratory of Biomaterials Design, Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University (Japan)

    2015-08-01

    The area intensity change of C1, C4, and C6 in spectrum obtained by {sup 13}C CP/MAS NMR and the mutual relationship between their changes were examined for cellulose samples treated with various concentrations of aqueous NaOH solutions under non-cooling and cooling conditions. The area intensity of C1-up and C6-down changed cooperatively with that of C4-down which corresponds to the crystallinity of samples: “-up” and “-down” are the up- and down- field component in a splitting peak of NMR spectrum, respectively. The intensity change of C1-up starts to decrease with decreasing in that of C4-down after that of C6-down is almost complete. These changes were more clearly observed for samples treated under cooling condition. It can be suggested that their characteristic change relates closely to the change in conformation of cellulose chains by induced decrystallization and the subsequent crystallization of cellulose II, and presumed that their changes at microscopic level relate to the macroscopic morphological changes such as contraction along the length of cellulose chains and recovery along the length. - Highlight: • Samples were mercerized at various NaOH concentrations under non-cooling and cooling. • The intensity change of C1 starts immediately after that of C6 is complete. • The creation of cell-II starts when decrystallization proceeds to a certain state. • This change relates closely to the change in conformation of cellulose chains. • The above change is more clearly found for samples treated under cooling.

  8. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane

    Science.gov (United States)

    Arjunan, V.; Anitha, R.; Devi, L.; Mohan, S.; Yang, Haifeng

    2015-01-01

    Aromatic epoxides are causative factors for mutagenic and carcinogenic activity of polycyclic arenes. The 1,2- or 2,3-epoxy compounds are widely used to a considerable extent in the textile, plastics, pharmaceutical, cosmetics, detergent and photochemical industries. The FTIR and FT-Raman spectra of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane are recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. The structure of the compound has been optimised with B3LYP method using 6-311++G** and cc-pVTZ basis sets. The IR and Raman intensities are determined. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of the compounds has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecules have been analysed.

  9. Formation of 1:1 and 2:1 host-guest inclusion complexes of α-cyclodextrin with cycloalkanols: A 1H and 13C NMR spectroscopic study

    Science.gov (United States)

    Akita, Tomoki; Yoshikiyo, Keisuke; Yamamoto, Tatsuyuki

    2014-09-01

    Binding constants (Ka's) for the formation of inclusion complexes of α-cyclodextrin (α-CD) with cycloalkanols (c-CnOH; n = 4-8) were determined by means of 1H and 13C NMR titration, under two different conditions: (i) only 1:1 host-guest inclusion complexes are formed when the guest is in excess; (ii) the formation of 2:1 inclusion complexes occurs only after that of 1:1 inclusion complexes, when the host is in excess. The results of this work showed that α-CD can include c-C4OH or c-C5OH only when the molar ratio is 1:1; larger ring-sized cycloalkanols such as c-C6OH, c-C7OH or c-C8OH can be included only when the molar ratio is 2:1. These findings, together with those obtained for the four derivatives of α-CD, per-6-O-methyl-α-CD, per-2-O-methyl-α-CD, per-3-O-methyl-α-CD, and per-2,6-di-O-methyl-α-CD, suggested that α-CD forms 2:1 inclusion complexes with c-C6OH, c-C7OH or c-C8OH in a tail-to-tail manner, in which the secondary hydroxy sides of the two CD molecules face each other. Two-dimensional ROESY measurements confirmed our results.

  10. Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) profiling and theoretical calculations of (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide: An anticonvulsant agent

    Science.gov (United States)

    Haress, Nadia G.; Govindarajan, Munusamy; AL-Wabli, Reem I.; Almutairi, Maha S.; Al-Alshaikh, Monirah A.; Al-Saadi, Abdulaziz A.; Attia, Mohamed I.

    2016-08-01

    Vibrational characteristics of the anticonvulsant agent, (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide ((2E)-IPHC) have been investigated. The computational data are obtained by adopting ab initio Hartree-Fock (HF) and DFT/B3LYP/6-31 + G(d,p) methods. The most stable conformer is identified by a potential energy scan. The optimized geometrical parameters indicated that the overall symmetry of the most stable conformer is CS. Atoms in molecules (AIM) analysis is contained out and the chemical bondings between the atoms are as characterized. Mulliken atomic charges and simulated thermo-molecular (heat capacity and enthalpy) characteristics of the (2E)-IPHC molecule also have been analyzed. The magnitude of the molecular electrostatic potential (MEP) of oxygen, hydrogen, and nitrogen atoms as well as phenyl and imidazole rings in the title molecule were investigated along with their contribution to the biological activity. The energy gap between HOMO and LUMO orbitals has been found to be 5.1334 eV in the gaseous phase. Excitation energies, oscillator strength and wavelengths were computed by the time-dependent density function theory (TD-DFT) approach. Predicted wavenumbers have been assigned and they are consistent with the experimental values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the (2E)-IPHC molecule were computed by the gauge independent atomic orbital (GIAO) method and were compared with the experimental results.

  11. Monitoring the Electrochemical Processes in the Lithium–Air Battery by Solid State NMR Spectroscopy

    OpenAIRE

    Leskes, Michal; Moore, Amy J.; Goward, Gillian R.; Grey, Clare P.

    2013-01-01

    A multi-nuclear solid-state NMR approach is employed to investigate the lithium–air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13C ss...

  12. Utilization of {sup 13}C-enriched substrates for the NMR study of the channelling of Krebs cycle intermediates in glioma C6; Utilisation de substrats enrichis en {sup 13}C pour l`etude par RMN de la canalisation des intermediaires du cycle de Krebs dans le gliome C6

    Energy Technology Data Exchange (ETDEWEB)

    Merle, M.; Peron, M.; Valeins, H.; Canioni, P. [Bordeaux-2 Univ., 33 (France)

    1994-12-31

    Unequal enrichments are observed for the C2 and C3 carbons of glutamate (C2>C3) and of aspartate (C3>C2) during incubation of C6 cells with (1-{sup 13} C) glucose. In order to study if this result is the result of an entry of {sup 13}C at the oxalo-acetate level or of another phenomenon, the enrichment distribution on asparte C1 and C4 carbons of C6 cells incubated with (1-{sup 13} C) glucose and the enrichment of C2 and C3 carbons of glutamate during cell incubation with (2-{sup 13} C) acetate, i.e. cases where the entry of {sup 13}C in the cycle, via the activity of the pyruvate carboxylase, is very unlikely, are examined. 4 figs., 1 tab., 1 ref.

  13. NMR doesn't lie or how solid-state NMR spectroscopy contributed to a better understanding of the nature and function of soil organic matter (Philippe Duchaufour Medal Lecture)

    Science.gov (United States)

    Knicker, Heike

    2016-04-01

    "Nuclear magnetic resonance (NMR) does not lie". More than anything else, this statement of a former colleague and friend has shaped my relation to solid-state NMR spectroscopy. Indeed, if this technique leads to results which contradict the expectations, it is because i) some parts of the instrument are broken, ii) maladjustment of the acquisition parameters or iii) wrong preparation or confusion of samples. However, it may be even simpler, namely that the expectations were wrong. Of course, for researchers, the latter is the most interesting possibility since it forces to reassess accepted views and to search for new explanations. As my major analytical tool, NMR spectroscopy has confronted me with this challenge often enough to turn this issue into the main subject of my talk and to share with the audience how it formed my understanding of function and nature of soil organic matter (SOM). Already shortly after its introduction into soil science in the 1980's, the data obtained with solid-state 13C NMR spectroscopy opened the stage for ongoing discussions, since they showed that in humified SOM aromatic carbon is considerably less important than previously thought. This finding had major implications regarding the understanding of the origin of SOM and the mechanisms by which it is formed. Certainly, the discrepancy between the new results and previous paradigms contributed to mistrust in the reliability of solid-state NMR techniques. The respective discussion has survived up to our days, although already in the 1980's and 1990's fundamental studies could demonstrate that quantitative solid-state NMR data can be obtained if i) correct acquisition parameters are chosen, ii) the impact of paramagnetic compounds is reduced and iii) the presence of soot in soils can be excluded. On the other hand, this mistrust led to a detailed analysis of the impact of paramagnetics on the NMR behavior of C groups which then improved our understanding of the role of carbohydrates

  14. Dissolution Dynamic Nuclear Polarization of Non-Self-Glassing Agents: Spectroscopy and Relaxation of Hyperpolarized [1-13C]Acetate

    DEFF Research Database (Denmark)

    Flori, Alessandra; Liserani, Matteo; Bowen, Sean;

    2015-01-01

    The intrinsic physicochemical properties of the sample formulation are the key factors for efficient hyperpolarization through dissolution dynamic nuclear polarization (dissolution-DNP). We provide a comprehensive characterization of the DNP process for Na-[1-13C]acetate selected as a model for n....... The results reported here describe the constraints of the acetate formulation useful for future studies in this field with non-self-glassing enriched molecules.......The intrinsic physicochemical properties of the sample formulation are the key factors for efficient hyperpolarization through dissolution dynamic nuclear polarization (dissolution-DNP). We provide a comprehensive characterization of the DNP process for Na-[1-13C]acetate selected as a model for non-self...

  15. Multiplicative or t1 Noise in NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Granwehr, Josef

    2005-01-25

    The signal in an NMR experiment is highly sensitive to fluctuations of the environment of the sample. If, for example, the static magnetic field B{sub 0}, the amplitude and phase of radio frequency (rf) pulses, or the resonant frequency of the detection circuit are not perfectly stable and reproducible, the magnetic moment of the spins is altered and becomes a noisy quantity itself. This kind of noise not only depends on the presence of a signal, it is in fact proportional to it. Since all the spins at a particular location in a sample experience the same environment at any given time, this noise primarily affects the reproducibility of an experiment, which is mainly of importance in the indirect dimensions of a multidimensional experiment, when intense lines are suppressed with a phase cycle, or for difference spectroscopy techniques. Equivalently, experiments which are known to be problematic with regard to their reproducibility, like flow experiments or experiments with a mobile target, tend to be affected stronger by multiplicative noise. In this article it is demonstrated how multiplicative noise can be identified and characterized using very simple, repetitive experiments. An error estimation approach is developed to give an intuitive, yet quantitative understanding of its properties. The consequences for multidimensional NMR experiments are outlined, implications for data analysis are shown, and strategies for the optimization of experiments are summarized.

  16. Saturation in Deuteron Hadamard NMR Spectroscopy of Solids

    Science.gov (United States)

    Greferath, M.; Blumich, B.; Griffith, W. M.; Hoatson, G. L.

    Hadamard NMR was investigated for wide-line solid-state deuteron spectroscopy by numerical simulations and experiments on hexamethylbenzene. Similar signal-to-noise ratios were obtained at large filter bandwidths (500 kHz) by both the quadrupolar echo and the Hadamard methods, although the excitation power differs by up to four orders in magnitude. Increasing the excitation power leads to systematic, noise-like features in Hadamard spectra. In contrast to phase modulation, simulations indicate that for amplitude modulation of the pseudorandom excitation, the pulse sequence burns a saturation hole into the lineshape at the carrier frequency. Violation of the cyclicity requirement by introduction of a recycle delay between successive Hadamard scans results in a high-frequency noise contribution. Finite pulse widths are shown not to cause significant spectral distortions.

  17. A survey on quantitative analysis of organic compounds by nuclear magnetic resonance (NMR) spectroscopy

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) spectroscopy is known as a powerful analytical technique, which is used to determine the structure of small and macro organic compounds. In recent years, 1H NMR is being recognized more and more as a quantitative analytical method, which is based on the principle where the area under a 1H NMR signal peak in solution state is proportional to the number of nuclei contributing to the peak. In this report, the basic concepts, developmental history and current state of the quantitative 1H NMR (qNMR) method are described. Furthermore, future prospect of the qNMR method is presented. (author)

  18. Determination of gluconeogenesis in man by the use of deuterium-NMR-spectroscopy

    CERN Document Server

    Rosian, E

    2000-01-01

    The aim of this dissertation is the quantification of the deuterium--distribution in human glucose by the use of the deuterium NMR spectroscopy of deuteriated water. The glucose production in human organism is composed of gluconeogenesis and glycolysis. The quantification of the part of gluconeogenesis on the total glucose production was determined by the use of deuterium NMR spectroscopy. (boteke)

  19. An Oil Spill in a Tube: An Accessible Approach for Teaching Environmental NMR Spectroscopy

    Science.gov (United States)

    Simpson, Andre´ J.; Mitchell, Perry J.; Masoom, Hussain; Mobarhan, Yalda Liaghati; Adamo, Antonio; Dicks, Andrew P.

    2015-01-01

    NMR spectroscopy has great potential as an instrumental method for environmental chemistry research and monitoring but may be underused in teaching laboratories because of its complexity and the level of expertise required in operating the instrument and interpreting data. This laboratory experiment introduces environmental NMR spectroscopy to…

  20. Effect of 13C enrichment in the glassing matrix on dynamic nuclear polarization of [1-13C]pyruvate

    OpenAIRE

    Lumata, Lloyd; Kovacs, Zoltan; Malloy, Craig; Sherry, A. Dean; Merritt, Matthew

    2011-01-01

    Dimethyl sulfoxide (DMSO) can effectively form a glassy matrix necessary for dynamic nuclear polarization (DNP) experiments. We tested the effects of 13C enrichment in DMSO on DNP of [1-13C]pyruvate doped with trityl radical OX063Me. We found that the polarization build-up time τ of pyruvate in 13C-labelled DMSO glassing solution is twice as fast as the unenriched DMSO while the NMR enhancement was unchanged. This indicates that 13C-13C spin diffusion is a limiting factor in the kinetics of d...

  1. Two-dimensional NMR spectroscopy as a tool to link soil organic matter composition to ecosystem processes

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Schleucher, Jürgen

    2014-05-01

    Environmental factors (e.g. temperature and moisture) and the size and composition of soil microbial populations are often considered the main drivers of soil organic matter (SOM) mineralization. Less consideration is given to the role of SOM as a substrate for microbial metabolism and the importance of the organo-chemical composition of SOM on decomposition. In addition, a fraction of the SOM is often considered as recalcitrant to mineralization leading to accumulation of SOM. However, recently the concept of intrinsic recalcitrance of SOM to mineralization has been questioned. The challenge in investigating the role of SOM composition on its mineralization to a large extent stems from the difficulties in obtaining high resolution characterization of a very complex matrix. 13C nuclear magnetic resonance (NMR) spectroscopy is a widely used tool to characterize SOM. However, SOM is a very complex mixture and in the resulting 13C NMR spectra, the identified functional groups may represent different molecular fragments that appear in the same spectral region leading to broad peaks. These overlaps defy attempts to identify molecular moieties, and this makes it impossible to derive information at a resolution needed for evaluating e.g. recalcitrance of SOM. Here we applied a method, developed in wood science for the pulp paper industry, to achieve a better characterization of SOM. We directly dissolved finely ground organic layers of boreal forest floors-litters, fibric and humic horizons of both coniferous and broadleaved stands-in dimethyl sulfoxide and analyzed the resulting solution with a two-dimensional (2D) 1H-13C NMR experiment. We will discuss methodological aspects related to the ability to identify and quantify individual molecular moieties in SOM. We will demonstrate how the spectra resolve signals of CH groups in a 2D plane determined by the 13C and 1H chemical shifts, thereby vastly increasing the resolving power and information content of NMR spectra. The

  2. Characterization of plant-derived carbon and phosphorus in lakes by sequential fractionation and NMR spectroscopy.

    Science.gov (United States)

    Liu, Shasha; Zhu, Yuanrong; Wu, Fengchang; Meng, Wei; He, Zhongqi; Giesy, John P

    2016-10-01

    Although debris from aquatic macrophytes is one of the most important endogenous sources of organic matter (OM) and nutrients in lakes, its biogeochemical cycling and contribution to internal load of nutrients in eutrophic lakes are still poorly understood. In this study, sequential fractionation by H2O, 0.1M NaOH and 1.0M HCl, combined with (13)C and (31)P NMR spectroscopy, was developed and used to characterize organic carbon (C) and phosphorus (P) in six aquatic plants collected from Tai Lake (Ch: Taihu), China. Organic matter, determined by total organic carbon (TOC), was unequally distributed in H2O (21.2%), NaOH (29.9%), HCl (3.5%) and residual (45.3%) fractions. For P in debris of aquatic plants, 53.3% was extracted by H2O, 31.9% by NaOH, and 11% by HCl, with 3.8% in residual fractions. Predominant OM components extracted by H2O and NaOH were carbohydrates, proteins and aliphatic acids. Inorganic P (Pi) was the primary form of P in H2O fractions, whereas organic P (Po) was the primary form of P in NaOH fractions. The subsequent HCl fractions extracted fewer species of C and P. Some non-extractable carbohydrates, aromatics and metal phytate compounds remained in residual fractions. Based on sequential extraction and NMR analysis, it was proposed that those forms of C (54.7% of TOC) and P (96.2% of TP) in H2O, NaOH and HCl fractions are potentially released to overlying water as labile components, while those in residues are stable and likely preserved in sediments of lakes. These results will be helpful in understanding internal loading of nutrients from debris of aquatic macrophytes and their recycling in lakes. PMID:27282495

  3. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy, E-mail: ramamoor@umich.edu [Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

    2016-01-21

    Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup 13}C/{sup 1}H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t{sub 1} and t{sub 3} periods, respectively. In addition to through-space and through-bond {sup 13}C/{sup 1}H and {sup 13}C/{sup 13}C chemical shift correlations, the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment also provides a COSY-type {sup 1}H/{sup 1}H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ({sup 1}H/{sup 1}H chemical shift correlation spectrum) at different {sup 13}C chemical shift frequencies from the 3D {sup 1}H/{sup 13}C/{sup 1}H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the

  4. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

    Science.gov (United States)

    Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

    2016-06-13

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of

  5. Ion counting in supercapacitor electrodes using NMR spectroscopy.

    Science.gov (United States)

    Griffin, John M; Forse, Alexander C; Wang, Hao; Trease, Nicole M; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P

    2014-01-01

    (19)F NMR spectroscopy has been used to study the local environments of anions in supercapacitor electrodes and to quantify changes in the populations of adsorbed species during charging. In the absence of an applied potential, anionic species adsorbed within carbon micropores (in-pore) are distinguished from those in large mesopores and spaces between particles (ex-pore) by a characteristic nucleus-independent chemical shift (NICS). Adsorption experiments and two-dimensional exchange experiments confirm that anions are in dynamic equilibrium between the in- and ex-pore environments with an exchange rate in the order of tens of Hz. (19)F in situ NMR spectra recorded at different charge states reveal changes in the intensity and NICS of the in-pore resonances, which are interpreted in term of changes in the population and local environments of the adsorbed anions that arise due to the charge-storage process. A comparison of the results obtained for a range of electrolytes reveals that several factors influence the charging mechanism. For a tetraethylammonium tetrafluoroborate electrolyte, positive polarisation of the electrode is found to proceed by anion adsorption at a low concentration, whereas increased ion exchange plays a more important role for a high concentration electrolyte. In contrast, negative polarization of the electrode proceeds by cation adsorption for both concentrations. For a tetrabutylammonium tetrafluoroborate electrolyte, anion expulsion is observed in the negative charging regime; this is attributed to the reduced mobility and/or access of the larger cations inside the pores, which forces the expulsion of anions in order to build up ionic charge. Significant anion expulsion is also observed in the negative charging regime for alkali metal bis(trifluoromethane)sulfonimide electrolytes, suggesting that more subtle factors also affect the charging mechanism.

  6. Mechanisms of Action of (Methacrylates in Hemolytic Activity, in Vivo Toxicity and Dipalmitoylphosphatidylcholine (DPPC Liposomes Determined Using NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Seiichiro Fujisawa

    2012-01-01

    Full Text Available We investigated the quantitative structure-activity relationships between hemolytic activity (log 1/H50 or in vivo mouse intraperitoneal (ip LD50 using reported data for α,β-unsaturated carbonyl compounds such as (methacrylate monomers and their 13C-NMR β-carbon chemical shift (δ. The log 1/H50 value for methacrylates was linearly correlated with the δCβ value. That for (methacrylates was linearly correlated with log P, an index of lipophilicity. The ipLD50 for (methacrylates was linearly correlated with δCβ but not with log P. For (methacrylates, the δCβ value, which is dependent on the π-electron density on the β-carbon, was linearly correlated with PM3-based theoretical parameters (chemical hardness, η; electronegativity, χ; electrophilicity, ω, whereas log P was linearly correlated with heat of formation (HF. Also, the interaction between (methacrylates and DPPC liposomes in cell membrane molecular models was investigated using 1H-NMR spectroscopy and differential scanning calorimetry (DSC. The log 1/H50 value was related to the difference in chemical shift (ΔδHa (Ha: H (trans attached to the β-carbon between the free monomer and the DPPC liposome-bound monomer. Monomer-induced DSC phase transition properties were related to HF for monomers. NMR chemical shifts may represent a valuable parameter for investigating the biological mechanisms of action of (methacrylates.

  7. Nuclear Magnetic Resonance (NMR) Spectroscopy For Metabolic Profiling of Medicinal Plants and Their Products.

    Science.gov (United States)

    Kumar, Dinesh

    2016-09-01

    NMR spectroscopy has multidisciplinary applications, including excellent impact in metabolomics. The analytical capacity of NMR spectroscopy provides information for easy qualitative and quantitative assessment of both endogenous and exogenous metabolites present in biological samples. The complexity of a particular metabolite and its contribution in a biological system are critically important for understanding the functional state that governs the organism's phenotypes. This review covers historical aspects of developments in the NMR field, its applications in chemical profiling, metabolomics, and quality control of plants and their derived medicines, foods, and other products. The bottlenecks of NMR in metabolic profiling are also discussed, keeping in view the future scope and further technological interventions. PMID:26575437

  8. Detection of Taurine in Biological Tissues by 33S NMR Spectroscopy

    Science.gov (United States)

    Musio, Roberta; Sciacovelli, Oronzo

    2001-12-01

    The potential of 33S NMR spectroscopy for biochemical investigations on taurine (2-aminoethanesulfonic acid) is explored. It is demonstrated that 33S NMR spectroscopy allows the selective and unequivocal identification of taurine in biological samples. 33S NMR spectra of homogenated and intact tissues are reported for the first time, together with the spectrum of a living mollusc. Emphasis is placed on the importance of choosing appropriate signal processing methods to improve the quality of the 33S NMR spectra of biological tissues.

  9. Nuclear Magnetic Resonance (NMR) Spectroscopy For Metabolic Profiling of Medicinal Plants and Their Products.

    Science.gov (United States)

    Kumar, Dinesh

    2016-09-01

    NMR spectroscopy has multidisciplinary applications, including excellent impact in metabolomics. The analytical capacity of NMR spectroscopy provides information for easy qualitative and quantitative assessment of both endogenous and exogenous metabolites present in biological samples. The complexity of a particular metabolite and its contribution in a biological system are critically important for understanding the functional state that governs the organism's phenotypes. This review covers historical aspects of developments in the NMR field, its applications in chemical profiling, metabolomics, and quality control of plants and their derived medicines, foods, and other products. The bottlenecks of NMR in metabolic profiling are also discussed, keeping in view the future scope and further technological interventions.

  10. Synthesis of ring-13C-labelled and ring-demethylated retinals

    International Nuclear Information System (INIS)

    Efficient synthetic schemes are described for the preparation of the required mono- and di-13C labelled retinals based on simple 13C labelled starting materials. Results from solid-state 13C-NMR spectroscopic studies of the various ring-13C labelled bacteriorhodopsins and rhodopsins are discussed. 404 refs.; 74 figs.; 16 tabs

  11. Isotope labeling of mammalian GPCRs in HEK293 cells and characterization of the C-terminus of bovine rhodopsin by high resolution liquid NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Karla; Richter, Christian; Klein-Seetharaman, Judith, E-mail: jks33@pitt.edu; Schwalbe, Harald [Johann Wolfgang Goethe-University, Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (Germany)], E-mail: schwalbe@nmr.uni-frankfurt.de

    2008-01-15

    High amino acid coverage labeling of the mammalian G protein coupled receptors (GPCR) rhodopsin was established with {sup 15}N and {sup 15}N/{sup 13}C isotopes. Rhodopsin was expressed at preparative scale in HEK293S cells and studied in full-length by NMR spectroscopy in detergent micelle solution. This resulted in the assignment and detailed study of the dynamic properties of the C-terminus of rhodopsin. The rhodopsin C-terminus is immobilized until Ala333, after which it becomes unstructured.

  12. Proton NMR spectroscopy of cytochrome c-554 from Alcaligenes faecalis.

    Science.gov (United States)

    Timkovich, R; Cork, M S

    1984-02-28

    Cytochrome c-554 from the bacterium Alcaligenes faecalis (ATCC 8750) is a respiratory electron-transport protein homologous to other members of the cytochrome c family. Its structure has been studied by 1H NMR spectroscopy in both the ferric and ferrous states. The ferric spectrum is characterized by downfield hyperfine-shifted heme methyl resonances at 46.25, 43.60, 38.40, and 36.73 ppm (25 degrees C, pH 7.1). Chemical shifts of these resonances change with temperature opposite to expectations derived from Curie's law. The pH behavior of the hyperfine-shifted resonances titrates with a pK of 6.3 that has been interpreted as due to ionization of a heme propionate. In the ferrous state, heme methyl, meso, and thioether bridge resonances have been observed and assigned. All aromatic proteins have been assigned according to the side chain of origin, and the structural environment about the sole tryptophan residue has been examined. The electron-transfer rate between ferric and ferrous forms has been estimated to be on the order of 3 X 10(8) M-1 s-1, which is the largest such self-exchange rate yet observed for a cytochrome. PMID:6324856

  13. Fast Two-Dimensional NMR Spectroscopy of High Molecular Weight Protein Assemblies

    International Nuclear Information System (INIS)

    An optimized NMR experiment that combines the advantages of methyl-TROSY and SOFAST-HMQC has been developed. It allows the recording of high quality methyl 1H-13C correlation spectra of protein assemblies of several hundreds of kDa in a few seconds. The SOFAST-methyl-TROSY-based experiment offers completely new opportunities for the study of structural and dynamic changes occurring in molecular nano-machines while they perform their biological function in vitro. (authors)

  14. Characterization of water-soluble organic matter in urban aerosol by 1H-NMR spectroscopy

    Science.gov (United States)

    Chalbot, Marie-Cecile G.; Chitranshi, Priyanka; Gamboa da Costa, Gonçalo; Pollock, Erik; Kavouras, Ilias G.

    2016-03-01

    The functional and 13C isotopic compositions of water-soluble organic carbon (WSOC) in atmospheric aerosol were determined by nuclear magnetic resonance (1H-NMR) and isotope ratio mass spectrometry (IRMS) in an urban location in the Southern Mississippi Valley. The origin of WSOC was resolved using the functional distribution of organic hydrogen, δ13C ratio, and positive matrix factorization (PMF). Three factors were retained based on NMR spectral bins loadings. Two factors (factors 1 and 3) demonstrated strong associations with the aliphatic region in the NMR spectra and levoglucosan resonances. Differences between the two factors included the abundance of the aromatic functional group for factor 1, indicating fresh emissions and, for factor 3, the presence of resonances attributed to secondary ammonium nitrate and low δ13C ratio values that are indicative of secondary organic aerosol. Factors 1 and 3 added 0.89 and 1.08 μgC m-3, respectively, with the highest contribution in the summer and fall. Factor 2 retained resonances consistent with saccharides and was attributed to pollen particles. Its contribution to WSOC varied from 0.22 μgC m-3 in winter to 1.04 μgC m-3 in spring.

  15. The phenomenology of optically pumped 13C NMR in diamond at 7.05 T: Room temperature polarization, orientation dependence, and the effect of defect concentration on polarization dynamics

    Science.gov (United States)

    Scott, Eric; Drake, Melanie; Reimer, Jeffrey A.

    2016-03-01

    Room temperature optical illumination of NV- imbibed single crystal diamonds with a 532 nm laser produces 13C polarization enhancements up to 200 times greater than that of the thermal equilibrium value at 7.05 T. We report high field NV- mediated 13C polarization as a function of the number and type (NV- and P1) of defects in commercially available diamonds. Surprisingly, both positive and negative 13C polarizations are observed depending on the orientation of the crystal with respect to the external magnetic field and the electric field vector of the optical illumination. The data reported herein cannot be explained by a previously proposed mechanism.

  16. Insulin induces a positive relationship between the rates of ATP and glycogen changes in isolated rat liver in presence of glucose; a 31P and 13C NMR study

    Directory of Open Access Journals (Sweden)

    Gin Henri

    2005-11-01

    Full Text Available Abstract Background There is an emerging theory suggesting that insulin, which is known to be the predominant postprandial anabolic hormone, is also a major regulator of mitochondrial oxidative phosphorylation in human skeletal muscle. However, little is known about its effects in the liver. Since there is a theoretical relationship between glycogen metabolism and energy status, a simultaneous and continuous investigation of hepatic ATP and glycogen content was performed in intact and isolated perfused liver by 31P and 13C nuclear magnetic resonance (NMR The hepatic rates of ATP and glycogen changes were evaluated with different concentrations of insulin and glucose during continuous and short-term supply. Results Liver from rats fed ad libitum were perfused with Krebs-Henseleit Buffer (KHB(controls or KHB containing 6 mM glucose, 30 mM glucose, insulin alone, insulin + 6 mM glucose, insulin + 30 mM glucose. In the control, glycogenolysis occurred at a rate of -0.53 ± 0.021 %·min-1 and ATP content decreased at a rate of -0.28 ± 0.029 %·min-1. In the absence of insulin, there was a close proportional relationship between the glycogen flux and the glucose concentration, whereas ATP rates never varied. With insulin + glucose, both glycogen and ATP rates were strongly related to the glucose concentration; the magnitude of net glycogen flux was linearly correlated to the magnitude of net ATP flux: fluxglycogen = 72.543(fluxATP + 172.08, R2 = 0.98. Conclusion Only the co-infusion of 30 mM glucose and insulin led to (i a net glycogen synthesis, (ii the maintenance of the hepatic ATP content, and a strong positive correlation between their net fluxes. This has never previously been reported. The specific effect of insulin on ATP change is likely related to a rapid stimulation of the hepatic mitochondrial oxidative phosphorylation. We propose that variations in the correlation between rates of ATP and glycogen changes could be a probe for insulin

  17. Characterizations of Some N-Substituted-salicylhydrazide in Mixtures by NMR Diffusion Ordered Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    张芳; 于贤勇; 陈忠; 林深; 刘世雄

    2003-01-01

    Several novel N-substituted-salicylhydrazide ligands, most of which are difficult to be purified or recrystallized so that their chemical configurations can not be confirmed by conventional NMR and/or X-ray diffraction techniques, were synthesized in this experiment, and their chemical configurations in mixture were analyzed and characterized by 2D NMR diffusion ordered spectroscopy (DOSY), a labor-saving virtual separation based on diffusion properties,together with several routine NMR techniques.

  18. Insight into the packing pattern of β2 fibrils: a model study of glutamic acid rich oligomers with 13C isotopic edited vibrational spectroscopy.

    Science.gov (United States)

    Chi, Heng; Welch, William R W; Kubelka, Jan; Keiderling, Timothy A

    2013-11-11

    Polyglutamic acid at low pH forms aggregates and self-assembles into a spiral, fibril-like superstructure formed as a β2-type sheet conformation that has a more compact intersheet packing than commonly found. This is stabilized by three-centered bifurcated hydrogen bonding of the amide carbonyl involving the protonated glutamic acid side chain. We report vibrational spectroscopic results and analyses for oligopeptides rich in glutamic acid enhanced with (13)C isotope labeling in a study modeling low pH poly-Glu self-assembly. Our results indicate bifurcated H-bonding and β2 aggregation can be attained in these model decamers, confirming they have the same conformations as poly-Glu. We also prepared conventional β1-sheet aggregates by rapid precipitation from the residual peptides in the higher pH supernatant. By comparing the isotope-enhanced IR and VCD spectra with theoretical predictions, we deduced that the oligo-Glu β2 structure is based on stacked, twisted, antiparallel β-sheets. The best fit to theoretical predictions was obtained for the strands being out of register, sequentially stepped by one residue, in a ladder-like fashion. The alternate β1 conformer for this oligopeptide was similarly shown to be antiparallel but was less ordered and apparently had a different registry in its aggregate structure.

  19. Integration of screening and identifying ligand(s) from medicinal plant extracts based on target recognition by using NMR spectroscopy

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Yalin Tang, Qian Shang, Junfeng Xiang, Qianfan Yang, Qiuju Zhou, Lin Li, Hong Zhang, Qian Li, Hongxia Sun, Aijiao Guan, Wei Jiang & Wei Gai ### Abstract This protocol presents the screening of ligand(s) from medicinal plant extracts based on target recognition by using NMR spectroscopy. A detailed description of sample preparation and analysis process is provided. NMR spectroscopies described here are 1H NMR, diffusion-ordered spectroscopy (DOSY), relaxation-edited NMR, ...

  20. Development of a micro flow-through cell for high field NMR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd Michael; McIntyre, Sarah K.

    2011-05-01

    A highly transportable micro flow-through detection cell for nuclear magnetic resonance (NMR) spectroscopy has been designed, fabricated and tested. This flow-through cell allows for the direct coupling between liquid chromatography (LC) and gel permeation chromatography (GPC) resulting in the possibility of hyphenated LC-NMR and GPC-NMR. The advantage of the present flow cell design is that it is independent and unconnected to the detection probe electronics, is compatible with existing commercial high resolution NMR probes, and as such can be easily implemented at any NMR facility. Two different volumes were fabricated corresponding to between {approx}3.8 and 10 {micro}L detection volume. Examples of the performance of the cell on different NMR instruments, and using different NMR detection probes were demonstrated.

  1. 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...

  2. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    Science.gov (United States)

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  3. Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R

    2009-01-01

    A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.

  4. Temperature-induced transitions in disordered proteins probed by NMR spectroscopy

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Poulsen, Flemming Martin; Kragelund, Birthe Brandt

    2012-01-01

    Intrinsically disordered proteins are abundant in nature and perform many important physiological functions. Multidimensional NMR spectroscopy has been crucial for the understanding of the conformational properties of disordered proteins and is increasingly used to probe their conformational ense...

  5. Facing and Overcoming Sensitivity Challenges in Biomolecular NMR Spectroscopy

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, Jan Henrik; Boebinger, Gregory S.; Comment, Arnaud;

    2015-01-01

    In the Spring of 2013, NMR spectroscopists convened at the Weizmann Institute in Israel to brainstorm on approaches to improve the sensitivity of NMR experiments, particularly when applied in biomolecular settings. This multi‐author interdisciplinary Review presents a state‐of‐the‐art description...

  6. An unprecedented up-field shift in the 13C NMR spectrum of the carboxyl carbons of the lantern-type dinuclear complex TBA[Ru2(O2CCH3)4Cl2] (TBA+ = tetra(n-butyl)ammonium cation).

    Science.gov (United States)

    Hiraoka, Yuya; Ikeue, Takahisa; Sakiyama, Hiroshi; Guégan, Frédéric; Luneau, Dominique; Gillon, Béatrice; Hiromitsu, Ichiro; Yoshioka, Daisuke; Mikuriya, Masahiro; Kataoka, Yusuke; Handa, Makoto

    2015-08-14

    A large up-field shift (-763 ppm) has been observed for the carboxyl carbons of the dichlorido complex TBA[Ru(2)(O(2)CCH(3))(4)Cl(2)] (TBA(+) = tetra(n-butyl)ammonium cation) in the (13)C NMR spectrum (CD(2)Cl(2) at 25 °C). The DFT calculations showed spin delocalization from the paramagnetic Ru(2)(5+) core to the ligands, in agreement with the large up-field shift.

  7. (17)O NMR and Raman Spectroscopies of Green Tea Infusion with Nanomaterial to Investigate Their Properties.

    Science.gov (United States)

    Zhou, Changyan; Zhang, Huiping; Yan, Ying; Zhang, Xinya

    2016-09-01

    (17)O NMR and Raman spectrograms of green tea infusions with nanomaterial were investigated. Different green tea infusions were prepared by steeping tea powder with different concentrations of nanomaterial aqueous solution. The tea infusions were tested with (17)O NMR and Raman spectroscopies. The (17)O NMR results showed that line width increased to 90 in the tea infusions after nanomaterial was added as a result of the effects of the self-association of Ca(2+) and tea polyphenol. The results of Raman spectroscopy showed that, in tea infusions, the enhancement of C─C and C─O stretching vibrations suggest an increase in the number of effective components in water.

  8. Organic structure determination using 2-D NMR spectroscopy a problem-based approach

    CERN Document Server

    Simpson, Jeffrey H

    2011-01-01

    Organic Structure Determination Using 2-D NMR Spectroscopy: A Problem-Based Approach, Second Edition, provides an introduction to the use of two-dimensional (2-D) nuclear magnetic resonance (NMR) spectroscopy to determine organic structure. The book begins with a discussion of the NMR technique, while subsequent chapters cover instrumental considerations; data collection, processing, and plotting; chemical shifts; symmetry and topicity; through-bond effects; and through-space effects. The book also covers molecular dynamics; strategies for assigning resonances to atoms within a molecule; s

  9. Combining NMR Spectroscopy and Gas-Liquid Chromatography for Analysis of the Fatty Acid Composition of Fenugreek Seed Oil (Trigonella foenum graecum L.)

    Science.gov (United States)

    Skakovskii, E. D.; Tychinskaya, L. Yu.; Mauchanava, V. A.; Karankevich, E. G.; Lamotkin, S. A.; Ahabalayeva, A. D.; Reshetnikov, V. N.

    2013-11-01

    1H and 13C NMR spectroscopy established that fenugreek seed oil consists mainly of triacylglycerides. Oleic and linoleic acids are found preferentially in the 2 position and α-linolenic acid is found preferentially in the 1,3 positions of the glycerol backbone. By combining NMR and gas-liquid chromatography, we have shown that fenugreek seeds contain 5.5 %-6.8 % oil, consisting mainly of unsaturated fatty acids (68.2 %-82.1 %): linoleic (31.3 %-46.8 %), α-linolenic (15.1 %-36.6 %), and oleic (11.6 %-21.3 %). The highest unsaturated fatty acid content is found in the cultivars D-19, Ovary Gold, Blidet, Ovary 4 and the lowest fatty acid content is found in the Metha cultivar. The percentage of polyunsaturated fatty acids is higher in oils of fenugreek cultivars from northern regions (Belarus, Hungary, France).

  10. Ultra fast magic angle spinning solid - state NMR spectroscopy of intact bone.

    Science.gov (United States)

    Singh, Chandan; Rai, Ratan Kumar; Kayastha, Arvind M; Sinha, Neeraj

    2016-02-01

    Ultra fast magic angle spinning (MAS) has been a potent method to significantly average out homogeneous/inhomogeneous line broadening in solid-state nuclear magnetic resonance (ssNMR) spectroscopy. It has given a new direction to ssNMR spectroscopy with its different applications. We present here the first and foremost application of ultra fast MAS (~60 kHz) for ssNMR spectroscopy of intact bone. This methodology helps to comprehend and elucidate the organic content in the intact bone matrix with resolution and sensitivity enhancement. At this MAS speed, amino protons from organic part of intact bone start to appear in (1) H NMR spectra. The experimental protocol of ultra-high speed MAS for intact bone has been entailed with an additional insight achieved at 60 kHz.

  11. Application of NMR Spectroscopy in the Analysis of Petroleum Derivatives and Products

    Directory of Open Access Journals (Sweden)

    Parlov Vuković, J.

    2012-11-01

    Full Text Available Complex chemical composition and physical properties of oil and fuel make their complete cha racterization very difficult. Components present in oil and oil products differ in structure, size, po larity and functionality. The presence and structure of specific hydrocarbons in final products depend on the processing procedure and type of the fuel. In order to predict or improve fuel pro perties it is necessary to determine its composition. Thus, new and more sophisticated analytical methods and procedures are constantly being developed. NMR spectroscopy plays a significant role in analysis and identification of complex hydrocarbon mixtures of petroleum and petroleum products. In this review, we describe the application of NMR spectroscopy for analyzing gasoline and diesel fuels. Hence, by using NMR spectroscopy it is possible to determine gasoline composition and presence of benzene and oxygenates, as well as some important physical characteristics of gasoli ne such as the research octane number. An application of different NMR techniques made it pos sible to characterize diesel fuels and middle oil distillates from various refineries. Data so obtained can be used in combination with statistical methods to predict fuel properties and to monitor pro- duction processes in the petroleum industry. NMR spectroscopy has proven useful in analysis of FAME which has recently been used as an ecologically acceptable alternative fuel. Furthermore, techniques such as CP/MAS for characterization of solid state oil-geochemical samples are inclu- ded. Also, possibilities of using NMR spectroscopy in the analysis of polymeric additives are di- scussed.

  12. The 13C bicarbonate method

    DEFF Research Database (Denmark)

    Junghans, Peter; Larsson, Caroline; Jensen, Rasmus Bovbjerg;

    2015-01-01

    We reconsider the principle of the (13)C bicarbonate (NaH(13)CO3) method ((13)C-BM) for the determination of the CO2 production to obtain an estimate of energy expenditure (EE). Its mathematical concept based on a three-compartmental model is related to the [(15)N]glycine end product method. The CO.......07; n = 8; p = .026). We suggest considering the (13)C-BM as a 'stand-alone' method to provide information on the total CO2 production as an index of EE....

  13. Synthesis of [5,6-13C2, 1-14C]olivetolic acid, methyl [1'-13C]olivetolate and [5,6-13C2, 1-14C]cannabigerolic acid

    International Nuclear Information System (INIS)

    Potential advanced intermediates in the biosynthesis of delta9-tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous 13C atoms and 14C. Methyl [5,6-13C2, 1-14C]olivetolate was prepared from lithium [13C2]acetylide and dimethyl [2-14C]malonate. Reaction with geranyl bromide afforded methyl [5,6-13C2, 1-14C]cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The 13C-13C couplings observable in the 13C NMR spectra of these 13C-enriched compounds and their synthetic precursors are recorded. Methyl [1'-14C]olivetolate was prepared from 13CO2 to confirm assignments of the 13C chemical shifts in the pentyl side chain of these compounds. (author)

  14. Selective excitation enables assignment of proton resonances and {sup 1}H-{sup 1}H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy, E-mail: ramamoor@umich.edu [Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of {sup 1}H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as {sup 13}C or {sup 15}N. In this method, after the initial preparation of proton magnetization and cross-polarization to {sup 13}C nuclei, transverse magnetization of desired {sup 13}C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific {sup 13}C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of {sup 1}H-{sup 1}H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  15. Determination of the Tautomeric Equilibria of Pyridoyl Benzoyl -Diketones in the Liquid and Solid State through the use of Deuterium Isotope Effects on 1H and 13C NMR Chemical Shifts and Spin Coupling Constants

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Borisov, Eugeny V.; Lindon, John C.

    2015-01-01

    The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in th...

  16. Valence neutrons' role in the collisions 13C+12C and 13C+13C

    International Nuclear Information System (INIS)

    The resonant behaviour is not limited to collisions between α-like nuclei: resonance structures have been observed in the direct channels for the 13C+12C and 13C+13C collisions; in the contrary, the resonances observed in the fusion channels are not so pronounced as in the 12C+12C case: the valence neutrons increase the number of reaction channels and the density of states in the states in the compound nuclei, the resonances are therefore 'washed out' and it is difficult to observe them experimentally

  17. Relationship between 13C NMR Chemical Shifts of Alkanes and Ionicity Index and Polarizability Effect Index%离子性指数、极化效应指数与烷烃13C NMR化学位移的关系研究

    Institute of Scientific and Technical Information of China (English)

    聂长明; 李忠海; 文松年

    2002-01-01

    定义了烷烃分子中碳原子的离子性指数(INI),用离子性指数(INI)、极化效应指数(PEI)及NiH(i=α,β,γ)结构信息参数研究了烷烃的13C NMR化学位移模型.结果表明,烷烃13C NMR化学位移(CS)可用下式来定量描述:CS=194.6156-37.7394(INI)+98.6505(ΣPEI)+27.1630(INI/ΣPEI)-652.910(ΣPEI/INI)+0.7735NαH+2.2468NβH-0.1742NγH用上式估算了304个碳原子的化学位移,平均绝对误差仅为0.77 δ,标准差0.9860δ,预测值与实验值非常吻合.

  18. GFT projection NMR spectroscopy for proteins in the solid state

    International Nuclear Information System (INIS)

    Recording of four-dimensional (4D) spectra for proteins in the solid state has opened new avenues to obtain virtually complete resonance assignments and three-dimensional (3D) structures of proteins. As in solution state NMR, the sampling of three indirect dimensions leads per se to long minimal measurement time. Furthermore, artifact suppression in solid state NMR relies primarily on radio-frequency pulse phase cycling. For an n-step phase cycle, the minimal measurement times of both 3D and 4D spectra are increased n times. To tackle the associated 'sampling problem' and to avoid sampling limited data acquisition, solid state G-Matrix Fourier Transform (SS GFT) projection NMR is introduced to rapidly acquire 3D and 4D spectral information. Specifically, (4,3)D (HA)CANCOCX and (3,2)D (HACA)NCOCX were implemented and recorded for the 6 kDa protein GB1 within about 10% of the time required for acquiring the conventional congeners with the same maximal evolution times and spectral widths in the indirect dimensions. Spectral analysis was complemented by comparative analysis of expected spectral congestion in conventional and GFT NMR experiments, demonstrating that high spectral resolution of the GFT NMR experiments enables one to efficiently obtain nearly complete resonance assignments even for large proteins.

  19. Ligand screening by saturation-transfer difference (STD) NMR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, V V

    2005-04-26

    NMR based methods to screen for high-affinity ligands have become an indispensable tool for designing rationalized drugs, as these offer a combination of good experimental design of the screening process and data interpretation methods, which together provide unprecedented information on the complex nature of protein-ligand interactions. These methods rely on measuring direct changes in the spectral parameters, that are often simpler than the complex experimental procedures used to study structure and dynamics of proteins. The goal of this review article is to provide the basic details of NMR based ligand-screening methods, with particular focus on the saturation transfer difference (STD) experiment. In addition, we provide an overview of other NMR experimental methods and a practical guide on how to go about designing and implementing them.

  20. In Situ Determination of Tacticity, Deactivation, and Kinetics in [rac-(C2H4(1-Indenyl)2)ZrMe][B(C6F5)4] and [Cp2ZrMe][B(C6F5)4]-Catalyzed Polymerization of 1-Hexene Using (13)C Hyperpolarized NMR.

    Science.gov (United States)

    Chen, Chia-Hsiu; Shih, Wei-Chun; Hilty, Christian

    2015-06-01

    The stereochemistry, kinetics, and mechanism of olefin polymerization catalyzed by a set of zirconium-based metallocenes was studied by NMR using dissolution dynamic nuclear polarization (DNP). Hyperpolarized 1-hexene was polymerized in situ with a C2 symmetric catalyst, [(EBI)ZrMe][B(C6F5)4] (EBI = rac-(C2H4(1-indenyl)2)), and a C2v symmetric catalyst, [(Cp)2ZrMe][B(C6F5)4] (Cp = cyclopentadienyl). Hyperpolarized (13)C NMR spectra were used to characterize product tacticity following initiation of the reaction. At the same time, a signal gain of 3 orders of magnitude from (13)C hyperpolarization enabled the real time observation of catalyst-polymeryl species and deactivation products, such as vinylidene and a Zr-allyl complex. The compounds appearing in the reaction provide evidence for the existence of β-hydride elimination and formation of a dormant site via a methane-generating mechanism. The presence of a deactivating mechanism was incorporated in a model used to determine kinetic parameters of the reaction. On this basis, rate constants were measured between 0.8 and 6.7 mol % of catalyst. The concentration dependence of the rate constants obtained indicates a second-order process for polymerization concomitant with a first-order process for deactivation. The simultaneous observation of both processes in the time evolution of (13)C NMR signals over the course of several seconds underlines the utility of hyperpolarized NMR for quantifying early events in polymerization reactions. PMID:25961793

  1. Localized double-quantum-filtered 1H NMR spectroscopy

    Science.gov (United States)

    Thomas, M. A.; Hetherington, H. P.; Meyerhoff, D. J.; Twieg, D. B.

    The image-guided in vivo spectroscopic (ISIS) pulse sequence has been combined with a double-quantum-filter scheme in order to obtain localized and water-suppressed 1H NMR spectra of J-coupled metabolites. The coherence-transfer efficiency associated with the DQ filter for AX and A 3X spin systems is described. Phantom results of carnosine, alanine, and ethanol in aqueous solution are presented. For comparison, the 1H NMR spectrum of alanine in aqueous solution with the binomial (1331, 2662) spin-echo sequence is also shown.

  2. New strategy for stable-isotope-aided, multidimensional NMR spectroscopy of DNA oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Okira; Tate, Shin-Ichi; Kainosho, Masatsune [Tokyo Metropolitan Univ., Tokyo (Japan)

    1994-12-01

    Nuclear Magnetic Resonance (NMR) is the most efficient method for determining the solution structures of biomolecules. By applying multidimensional heteronuclear NMR techniques to {sup 13}C/{sup 15}N-labeled proteins, we can determine the solution structures of proteins with molecular mass of 20 to 30kDa at an accuracy similar to that of x-ray crystallography. Improvements in NMR instrumentation and techniques as well as the development of protein engineering methods for labeling proteins have rapidly advanced multidimensional heteronuclear NMR of proteins. In contrast, multidimensional heteronuclear NMR studies of nucleic acids is less advanced because there were no efficient methods for preparing large amounts of labeled DNA/RNA oligomers. In this report, we focused on the chemical synthesis of DNA oligomers labeled at specific residue(s). RNA oligomers with specific labels, which are difficult to synthesize by the enzyme method, can be synthesized by the chemical method. The specific labels are useful for conformational analysis of larger molecules such as protein-nucleic acid complexes.

  3. Biosynthetic studies on mycotoxins using multiple stable isotope labelling and NMR spectroscopy

    International Nuclear Information System (INIS)

    The biosynthesis of terretonin and mevinolin, polyketide metabolites from mycotoxin-producing Aspergillus terreus strains, have been examined by incorporation of precursors multiply-labelled with 13C, 18O, and 2H. A variety of one and two dimensional NMR techniques permit facile spectral assignment and location of labelled sites. The results show that the polyketide parts of both metabolites, terretonin and mevinolin, are assembled by enzymes similar to those of fatty acid biosynthesis and that extensive oxidative transformation occurs in the later stages of biosynthesis. 25 refs.; 8 figs.; 1 table

  4. Computational Analysis of Solvent Effects in NMR Spectroscopy.

    Science.gov (United States)

    Dračínský, Martin; Bouř, Petr

    2010-01-12

    Solvent modeling became a standard part of first principles computations of molecular properties. However, a universal solvent approach is particularly difficult for the nuclear magnetic resonance (NMR) shielding and spin-spin coupling constants that in part result from collective delocalized properties of the solute and the environment. In this work, bulk and specific solvent effects are discussed on experimental and theoretical model systems comprising solvated alanine zwitterion and chloroform molecules. Density functional theory computations performed on larger clusters indicate that standard dielectric continuum solvent models may not be sufficiently accurate. In some cases, more reasonable NMR parameters were obtained by approximation of the solvent with partial atomic charges. Combined cluster/continuum models yielded the most reasonable values of the spectroscopic parameters, provided that they are dynamically averaged. The roles of solvent polarizability, solvent shell structure, and bulk permeability were investigated. NMR shielding values caused by the macroscopic solvent magnetizability exhibited the slowest convergence with respect to the cluster size. For practical computations, however, inclusion of the first solvation sphere provided satisfactory corrections of the vacuum values. The simulations of chloroform chemical shifts and CH J-coupling constants were found to be very sensitive to the molecular dynamics model used to generate the cluster geometries. The results show that computationally efficient solvent modeling is possible and can reveal fine details of molecular structure, solvation, and dynamics. PMID:26614339

  5. Solid-State NMR Spectroscopy of Metal–Organic Framework Compounds (MOFs

    Directory of Open Access Journals (Sweden)

    Stefan Kaskel

    2012-11-01

    Full Text Available Nuclear Magnetic Resonance (NMR spectroscopy is a well-established method for the investigation of various types of porous materials. During the past decade, metal–organic frameworks have attracted increasing research interest. Solid-state NMR spectroscopy has rapidly evolved into an important tool for the study of the structure, dynamics and flexibility of these materials, as well as for the characterization of host–guest interactions with adsorbed species such as xenon, carbon dioxide, water, and many others. The present review introduces and highlights recent developments in this rapidly growing field.

  6. Effect of organic carbon chemistry on sorption of atrazine and metsulfuron-methyl as determined by (13)C-NMR and IR spectroscopy.

    Science.gov (United States)

    Dutta, Anirban; Mandal, Abhishek; Manna, Suman; Singh, S B; Berns, Anne E; Singh, Neera

    2015-10-01

    Soil organic matter (SOM) content is the major soil component affecting pesticide sorption. However, recent studies have highlighted the fact that it is not the total carbon content of the organic matter, but its chemical structure which have a profound effect on the pesticide's sorption. In the present study, sorption of atrazine and metsulfuron-methyl herbicides was studied in four SOM fractions viz. commercial humic acid, commercial lignin, as well as humic acid and humin extracted from a compost. Sorption data was fitted to the Freundlich adsorption equation. In general, the Freundlich slope (1/n) values for both the herbicides were herbicides, showed minimum desorption. Sorption of atrazine was best positively correlated with the alkyl carbon (adjusted R (2) = 0.748) and carbonyl carbon (adjusted R (2) = 0.498) but, their effect was statistically nonsignificant (P = 0.05). Metsulfuron-methyl sorption showed best positive correlation with carbonyl carbon (adjusted R (2) = 0.960; P = 0.05) content. Sorption of both the herbicides showed negative correlation with O/N-alkyl carbon. Correlation of herbicide's sorption with alkyl and carbonyl carbon content of SOM fractions suggested their contribution towards herbicide sorption. But, sorption of metsulfuron-methyl, relatively more polar than atrazine, was mainly governed by the polar groups in SOM. IR spectra showed that H-bonds and charge-transfer bonds between SOM fraction and herbicides probably operated as mechanisms of adsorption. PMID:26353968

  7. Effect of organic carbon chemistry on sorption of atrazine and metsulfuron-methyl as determined by (13)C-NMR and IR spectroscopy.

    Science.gov (United States)

    Dutta, Anirban; Mandal, Abhishek; Manna, Suman; Singh, S B; Berns, Anne E; Singh, Neera

    2015-10-01

    Soil organic matter (SOM) content is the major soil component affecting pesticide sorption. However, recent studies have highlighted the fact that it is not the total carbon content of the organic matter, but its chemical structure which have a profound effect on the pesticide's sorption. In the present study, sorption of atrazine and metsulfuron-methyl herbicides was studied in four SOM fractions viz. commercial humic acid, commercial lignin, as well as humic acid and humin extracted from a compost. Sorption data was fitted to the Freundlich adsorption equation. In general, the Freundlich slope (1/n) values for both the herbicides were <1. Except for atrazine sorption on commercial humic acid, metsulfuron-methyl was more sorbed. Desorption results suggested that atrazine was more desorbed than metsulfuron-methyl. Lignin, which showed least sorption of both the herbicides, showed minimum desorption. Sorption of atrazine was best positively correlated with the alkyl carbon (adjusted R (2) = 0.748) and carbonyl carbon (adjusted R (2) = 0.498) but, their effect was statistically nonsignificant (P = 0.05). Metsulfuron-methyl sorption showed best positive correlation with carbonyl carbon (adjusted R (2) = 0.960; P = 0.05) content. Sorption of both the herbicides showed negative correlation with O/N-alkyl carbon. Correlation of herbicide's sorption with alkyl and carbonyl carbon content of SOM fractions suggested their contribution towards herbicide sorption. But, sorption of metsulfuron-methyl, relatively more polar than atrazine, was mainly governed by the polar groups in SOM. IR spectra showed that H-bonds and charge-transfer bonds between SOM fraction and herbicides probably operated as mechanisms of adsorption.

  8. Multisite Kinetic Modeling of 13C Metabolic MR Using [1-13C]Pyruvate

    Directory of Open Access Journals (Sweden)

    Pedro A. Gómez Damián

    2014-01-01

    Full Text Available Hyperpolarized 13C imaging allows real-time in vivo measurements of metabolite levels. Quantification of metabolite conversion between [1-13C]pyruvate and downstream metabolites [1-13C]alanine, [1-13C]lactate, and [13C]bicarbonate can be achieved through kinetic modeling. Since pyruvate interacts dynamically and simultaneously with its downstream metabolites, the purpose of this work is the determination of parameter values through a multisite, dynamic model involving possible biochemical pathways present in MR spectroscopy. Kinetic modeling parameters were determined by fitting the multisite model to time-domain dynamic metabolite data. The results for different pyruvate doses were compared with those of different two-site models to evaluate the hypothesis that for identical data the uncertainty of a model and the signal-to-noise ratio determine the sensitivity in detecting small physiological differences in the target metabolism. In comparison to the two-site exchange models, the multisite model yielded metabolic conversion rates with smaller bias and smaller standard deviation, as demonstrated in simulations with different signal-to-noise ratio. Pyruvate dose effects observed previously were confirmed and quantified through metabolic conversion rate values. Parameter interdependency allowed an accurate quantification and can therefore be useful for monitoring metabolic activity in different tissues.

  9. High resolution triple resonance micro magic angle spinning NMR spectroscopy of nanoliter sample volumes.

    Science.gov (United States)

    Brauckmann, J Ole; Janssen, J W G Hans; Kentgens, Arno P M

    2016-02-14

    To be able to study mass-limited samples and small single crystals, a triple resonance micro-magic angle spinning (μMAS) probehead for the application of high-resolution solid-state NMR of nanoliter samples was developed. Due to its excellent rf performance this allows us to explore the limits of proton NMR resolution in strongly coupled solids. Using homonuclear decoupling we obtain unprecedented (1)H linewidths for a single crystal of glycine (Δν(CH2) = 0.14 ppm) at high field (20 T) in a directly detected spectrum. The triple channel design allowed the recording of high-resolution μMAS (13)C-(15)N correlations of [U-(13)C-(15)N] arginine HCl and shows that the superior (1)H resolution opens the way for high-sensitivity inverse detection of heteronuclei even at moderate spinning speeds and rf-fields. Efficient decoupling leads to long coherence times which can be exploited in many correlation experiments.

  10. Residue-specific membrane location of peptides and proteins using specifically and extensively deuterated lipids and {sup 13}C-{sup 2}H rotational-echo double-resonance solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Xie Li; Ghosh, Ujjayini; Schmick, Scott D.; Weliky, David P., E-mail: weliky@chemistry.msu.edu [Michigan State University, Department of Chemistry (United States)

    2013-01-15

    Residue-specific location of peptides in the hydrophobic core of membranes was examined using {sup 13}C-{sup 2}H REDOR and samples in which the lipids were selectively deuterated. The transmembrane topology of the KALP peptide was validated with this approach with substantial dephasing observed for deuteration in the bilayer center and reduced or no dephasing for deuteration closer to the headgroups. Insertion of {beta} sheet HIV and helical and {beta} sheet influenza virus fusion peptides into the hydrophobic core of the membrane was validated in samples with extensively deuterated lipids.

  11. Synthesis of 13C and 2H labelled retinals: spectroscopic investigations on isotopically labelled rhodopsin and bacteriorhodopsin

    International Nuclear Information System (INIS)

    In order to develop probes of the structure of chromophores, the author introduces isotopic modifications at specific chromophoric positions as structural probes. To obtain bacteriorhodopsin, rhodopsin and their photoproducts labelled in the chromophore at selected positions, bacterioopsin and opsin were reacted with the appropriate labelled a11-trans and 11-cis retinals. The author describes the synthesis of a11-trans retinal selectively 13C labelled at different positions. The characterization of these labelled a11-trans retinals by mass spectrometry, 300 MHz 1H NMR and 75 MHz 13C NMR spectroscopy is given. The photochemical preparation and isolation of the pure 9-, 11- and 13-cis forms is described in the experimental part. (Auth.)

  12. Flavonoids from Lonchocarpus araripensis (Leguminoseae): isolation, unequivocal assignment of NMR signals {sup 1}H and {sup 13}C and conformational analysis; Flavonoides de Lonchocarpus araripensis (Leguminoseae): isolamento, atribuicao inequivoca dos sinais de RMN {sup 1}H e {sup 13}C e analise conformacional

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Almi F.; Ferreira, Daniele A.; Monte, Francisco Jose Q., E-mail: fmonte@dqoi.ufc.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Centro de Ciencias. Departamento de Quimica Organica e Inorganica; Braz-Filho, Raimundo [Universidade Estadual do Norte Fluminense (UENF), Campo dos Goytacazes, RJ (Brazil). Centro de Ciencias Tecnologicas. Laboratorio de Ciencias Quimicas

    2014-07-01

    In a continuing investigation for potentially bioactive natural products, flavonoids were isolated from Lonchocarpus araripensis (Leguminoseae) and identified as 3-methoxy-6-O-prenyl-6'',6''-dimethylchromene-[7,8,2'',3'']-flavone (1), 3,6-dimethoxy-6'',6''-dimethylchromene-[7,8,2'',3'']-flavone (2) and 3,5,8-trimethoxy-[6,7,2{sup ,}3{sup ]}-furanoflavone (3). This is the first time compound 3 has been described. Compound 2 has been previously isolated from roots while this is the first time 1 is reported in this species. Complete NMR assignments are given for 1 ,2 and 3 together with the determination of conformation for 1. (author)

  13. Synthesis of aromatic (13)C/(2)H-α-ketoacid precursors to be used in selective phenylalanine and tyrosine protein labelling.

    Science.gov (United States)

    Lichtenecker, R J

    2014-10-14

    Recent progress in protein NMR spectroscopy revealed aromatic residues to be valuable information sources for performing structure and motion analysis of high molecular weight proteins. However, the applied NMR experiments require tailored isotope labelling patterns in order to regulate spin-relaxation pathways and optimize magnetization transfer. We introduced a methodology to use α-ketoacids as metabolic amino acid precursors in cell-based overexpression of phenylalanine and/or tyrosine labelled proteins in a recent publication, which we have now developed further by providing synthetic routes to access the corresponding side-chain labelled precursors. The target compounds allow for selective introduction of (13)C-(1)H spin systems in a highly deuterated chemical environment and feature alternating (12)C-(13)C-(12)C ring-patterns. The resulting isotope distribution is especially suited to render straightforward (13)C spin relaxation experiments possible, which provide insight into the dynamic properties of the corresponding labelled proteins.

  14. 2D-Cosy NMR Spectroscopy as a Quantitative Tool in Biological Matrix: Application to Cyclodextrins.

    Science.gov (United States)

    Dufour, Gilles; Evrard, Brigitte; de Tullio, Pascal

    2015-11-01

    Classical analytical quantifications in biological matrices require time-consuming sample pre-treatments and extractions. Nuclear magnetic resonance (NMR) analysis does not require heavy sample treatments or extractions which therefore increases its accuracy in quantification. In this study, even if quantitative (q)NMR could not be applied to 2D spectra, we demonstrated that cross-correlations and diagonal peak intensities have a linear relationship with the analyzed pharmaceutical compound concentration. This work presents the validation process of a 2D-correlation spectroscopy (COSY) NMR quantification of 2-hydroxypropyl-β-cyclodextrin in plasma. Specificity, linearity, precision (repeatability and intermediate precision), trueness, limits of quantification (LOQs), and accuracy were used as validation criteria. 2D-NMR could therefore be used as a valuable and accurate analytical technique for the quantification of pharmaceutical compounds, including hardly detectable compounds such as cyclodextrins or poloxamers, in complex biological matrices based on a calibration curve approach.

  15. Online T5 learning model to enhance chemistry students’ understanding of NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    Saksri Supasorn

    2014-08-01

    Full Text Available Regular lecture-based teaching approaches sometimes fail to enhance students’ understanding of some practice-based chemistry topics such as Nuclear Magnetic Resonance (NMR spectroscopy. A new task-based approach called the T5 learning model was introduced for 48 students studying NMR in the Spectroscopic Methods for Chemical Identification course in 2011. Four different NMR learning environments based on T5 learning models were developed. The students were requested to participate in the following online processes in each environment: 1 complete an individual task, 2 provide feedback and evaluate three anonymous peer tasks, 3 adjust their individual task and evaluate peer feedback, 4 complete a team task and evaluate the effort of each group member, and 5 get feedback from instructor to fulfill understanding. The result showed that the students obtained post-achievement NMR score (mean 24.25, SD 4.80 statistically significantly higher than pre- achievement score (mean 12.29, SD 1.69 at p-value of 0.05. In addition, the implementation of T5-D4LP NMR course in each year during 2010-2012 showed that the students achieved high score (about 70% in the NMR topics. The student evaluation of the T5 NMR learning environments revealed that they agreed that peer feedback with instructor facilitation engaged them in deep learning and effectively promoted their conceptual understanding.

  16. Surface Binding of TOTAPOL Assists Structural Investigations of Amyloid Fibrils by Dynamic Nuclear Polarization NMR Spectroscopy.

    Science.gov (United States)

    Nagaraj, Madhu; Franks, Trent W; Saeidpour, Siavash; Schubeis, Tobias; Oschkinat, Hartmut; Ritter, Christiane; van Rossum, Barth-Jan

    2016-07-15

    Dynamic nuclear polarization (DNP) NMR can enhance sensitivity but often comes at the price of a substantial loss of resolution. Two major factors affect spectral quality: low-temperature heterogeneous line broadening and paramagnetic relaxation enhancement (PRE) effects. Investigations by NMR spectroscopy, isothermal titration calorimetry (ITC), and EPR revealed a new substantial affinity of TOTAPOL to amyloid surfaces, very similar to that shown by the fluorescent dye thioflavin-T (ThT). As a consequence, DNP spectra with remarkably good resolution and still reasonable enhancement could be obtained at very low TOTAPOL concentrations, typically 400 times lower than commonly employed. These spectra yielded several long-range constraints that were difficult to obtain without DNP. Our findings open up new strategies for structural studies with DNP NMR spectroscopy on amyloids that can bind the biradical with affinity similar to that shown towards ThT. PMID:27147408

  17. Structural investigation of bistrifluron using x-ray crystallography, NMR spectroscopy, and molecular modeling

    CERN Document Server

    Moon, J K; Rhee, S K; Kim, G B; Yun, H S; Chung, B J; Lee, S S; Lim, Y H

    2002-01-01

    A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

  18. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    Energy Technology Data Exchange (ETDEWEB)

    Richards, T.

    1984-09-01

    NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures.

  19. 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...

  20. High-Resolution Solid-State NMR Spectroscopy: Characterization of Polymorphism in Cimetidine, a Pharmaceutical Compound

    Science.gov (United States)

    Pacilio, Julia E.; Tokarski, John T.; Quiñones, Rosalynn; Iuliucci, Robbie J.

    2014-01-01

    High-resolution solid-state NMR (SSNMR) spectroscopy has many advantages as a tool to characterize solid-phase material that finds applications in polymer chemistry, nanotechnology, materials science, biomolecular structure determination, and others, including the pharmaceutical industry. The technology associated with achieving high resolution…

  1. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    International Nuclear Information System (INIS)

    NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures

  2. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T;

    1994-01-01

    The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human...

  3. Structural analysis of the carbohydrate chains of glycoproteins by 500-MHz 1H-NMR spectroscopy

    International Nuclear Information System (INIS)

    This thesis deals with the structural analysis by 500-MHz 1H-NMR spectroscopy of carbohydrate chains obtained from glycoproteins. In the chapters 1 to 6 the structural analysis of N-glycosidically linked carbohydrate chains is described. The chapters 7 to 10 describe the structural analysis of O-glycosidically linked carbohydrate chains. 381 refs.; 44 figs.; 24 tabs.; 7 schemes

  4. Structural rearrangements of membrane proteins probed by water-edited solid-state NMR spectroscopy

    NARCIS (Netherlands)

    Ader, C.; Schneider, R.; Seidel, K.; Etzkorn, M.; Becker, S.; Baldus, M.

    2009-01-01

    We show that water-edited solid-state NMR spectroscopy allows for probing global protein conformation and residue-specific solvent accessibility in a lipid bilayer environment. The transfer dynamics can be well described by a general time constant, irrespective of protein topology and lipid environm

  5. The Validity of High Temperature Approximation in NMR Spectroscopy and Its Related Problems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A large body of conspicuous publications [1] in recent years asserts that the high temperature approximation (HTA), a mostly tested and most widely used assumption in NMR spectroscopy and MRI technology, is invalid for concentrated samples in high magnetic fields such as for a proton COSY spectrum of water [1].

  6. Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory

    Science.gov (United States)

    Pavel, John T.; Hyde, Erin C.; Bruch, Martha D.

    2012-01-01

    This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possible…

  7. Characterization of partitioning relevant lanthanide and actinide complexes by NMR spectroscopy

    International Nuclear Information System (INIS)

    In the present work the interaction of N-donor ligands, such as 2,6-Bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (nPrBTP) and 2,6-Bis(5-(2,2-dimethylpropyl)1H-pyrazol)-3-yl-pyridine (C5-BPP), with trivalent lanthanide and actinide ions was studied. Ligands of this type show a high selectivity for the separation of trivalent actinide ions over lanthanides from nitric acid solutions. However, the reason for this selectivity, which is crucial for future partitioning and transmutation strategies for radioactive wastes, is still unknown. So far, the selectivity of some N-donor ligands is supposed to be an effect of an increased covalency in the actinide-ligand bond, compared to the lanthanide compounds. NMR spectroscopy on paramagnetic metal complexes is an excellent tool for the elucidation of bonding modes. The overall paramagnetic chemical shift consists of two contributions, the Fermi Contact Shift (FCS), due to electron spin delocalisation through covalent bonds, and the Pseudo Contact Shift (PCS), which describes the dipolar coupling of the electron magnetic moment and the nuclear spin. By assessing the FCS share in the paramagnetic shift, the degree of covalency in the metal-ligand bond can be gauged. Several methods to discriminate FCS and PCS have been used on the data of the nPrBTP- and C5-BPP-complexes and were evaluated regarding their applicability on lanthanide and actinide complexes with N-donor ligands. The study comprised the synthesis of all Ln(III) complexes with the exceptions of Pm(III) and Gd(III) as well as the Am(III) complex as a representative of the actinide series with both ligands. All complexes were fully characterised (1H, 13C and 15N spectra) using NMR spectroscopy. By isotope enrichment with the NMR-active 15N in positions 8 and 9 in both ligands, resonance signals of these nitrogen atoms were detected for all complexes. The Bleaneymethod relies on different temperature dependencies for FCS (T-1) and PCS (T-2) that occur upon description

  8. Detection of kestoses and kestose-related oligosaccharides in extracts of Festuca arundinacea, Dactylis glomerate L. , and Asparagus officinalis L. root cultures and invertase by sup 13 C and sup 1 H nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Forsythe, K.L.; Feather, M.S.; Gracz, H.; Wong, T.C. (Univ. of Missouri, Columbia (USA))

    1990-04-01

    Previous studies show that {sup 13}C nuclear magnetic resonance spectroscopy can be used to detect and identify mixtures of 1-kestose and neokestose after conversion to the acetate derivatives. In this study, unequivocal assignments are made for the anomeric carbon and proton signals for the above two trisaccharide acetates as well as for 6-kestose hendecaacetate and for nystose tetradecaacetate (a 1-kestose-derived tetrasaccharide). A number of oligosaccharide fractions were isolated from several plant species, converted to the acetates, and nuclear magnetic resonance spectra obtained. Using the above reference data, the following information was obtained. The trisaccharide fraction from Dactylis gomerata L. stem tissue and Asparagus officinalis L. roots contain both 1-kestose and neokestose, and the tetrasaccharide fractions contain three components, one of which is nystose. Penta- and hexasaccharide acetates were also isolated from A. officinalis L. roots and were found to contain, respectively, four and at least five components. All components of both of the above species appear to contain a kestose residue and to be produced by the sequential addition of fructofuranosyl units to these. The trisaccharide fraction from Festuca arundinacea is complex, and contains at least five different components, two of which appear to be 1-kestose and neokestose.

  9. Intramolecular hydrogen-bonding studies by NMR spectroscopy

    CERN Document Server

    Cantalapiedra, N A

    2000-01-01

    o-methoxybenzamide and N-methyl-o-methylbenzamide, using the pseudo-contact shifts calculated from the sup 1 H and sup 1 sup 3 C NMR spectra. The main conformation present in solution for o-fluorobenzamide was the one held by an intramolecular N-H...F hydrogen bond. Ab-initio calculations (at the RHF/6-31G* level) have provided additional data for the geometry of the individual molecules. A conformational equilibrium study of some nipecotic acid derivatives (3-substituted piperidines: CO sub 2 H, CO sub 2 Et, CONH sub 2 , CONHMe, CONEt sub 2) and cis-1,3-disubstituted cyclohexane derivatives (NHCOMe/CO sub 2 Me, NHCOMe/CONHMe, NH sub 2 /CO sub 2 H) has been undertaken in a variety of solvents, in order to predict the intramolecular hydrogen-bonding energies involved in the systems. The conformer populations were obtained by direct integration of proton peaks corresponding to the equatorial and axial conformations at low temperature (-80 deg), and by geometrically dependent coupling constants ( sup 3 J sub H s...

  10. Grape juice quality control by means of ¹H nmr spectroscopy and chemometric analyses

    Directory of Open Access Journals (Sweden)

    Caroline Werner Pereira da Silva Grandizoli

    2014-01-01

    Full Text Available This work shows the application of ¹H NMR spectroscopy and chemometrics for quality control of grape juice. A wide range of quality assurance parameters were assessed by single ¹H NMR experiments acquired directly from juice. The investigation revealed that conditions and time of storage should be revised and indicated on all labels. The sterilization process of homemade grape juices was efficient, making it possible to store them for long periods without additives. Furthermore, chemometric analysis classified the best commercial grape juices to be similar to homemade grape juices, indicating that this approach can be used to determine the authenticity after adulteration.

  11. Synthesis and proton NMR spectroscopy of intra-vesicular gamma-aminobutyric acid (GABA).

    Science.gov (United States)

    Wang, Luke Y-J; Tong, Rong; Kohane, Daniel S

    2013-01-01

    We report the synthesis of vesicles containing gamma-aminobutyric acid (GABA), and their proton nuclear magnetic resonance ((1)H NMR) spectra. These vesicles were constructed to more closely mimic the intracellular environment wherein GABA exists. For this study, these GABA-containing vesicles were examined under (1)H NMR as a potential platform for future studies on the differences between aqueous phantoms, ex vivo brain extracts, and in vivo magnetic resonance spectroscopy results. We found that intra-vesicular GABA faithfully yielded the chemical shifts and J-coupling constants of free aqueous GABA, alongside the chemical shift signals of the vesicle wall.

  12. Quantitative analysis of water heavy by NMR spectroscopy

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance has been applied to a wide variety of quantitative problems. A typical example has been the determination of isotopic composition. In this paper two different analytical methods for the determination of water in deuterium oxide are described. The first one, employs acetonitril as an internal standard compound and in the second one calibration curve of signal integral curve versus amount of D2O is constructed. Both methods give results comparable to those of mass spectrometry of IR spectroscopy. (Author) 5 refs

  13. 31P NMR spectroscopy of tumors in the evaluation of response to therapy

    International Nuclear Information System (INIS)

    In this thesis the effects of different kinds of therapy on tumour metabolism were investigated by in vivo 31P NMR spectroscopy. From the first five chapters (laboratory-animal studies) it turns out that after radiotherapy as well as after hyperthermy or chemoterapy changes can be observed in the 31P NMR spectra of tumours. In a number of cases a durable decline occurred in the ratio of the high-energetic adenosinephosphate (ATP) and the low-energeic anorganic phosphate, cuased by the mortification of tumourcells. On the other hand, tumour regression after effective chemotherapy resulted in a growth of the ATP/Pi ratio. In one case a temporary drop occurred which could be related to a temporary decrease in tumour perfusion. In anoter case a temporary drop of the ATP/Pi ratio correlated with resistence against treatment with cis-diaminodichoroplatina. In contrast with the changes in ATP/Pi ratio, the changes, after (chemo)therapy, in tumour pH do not seem to be related with the respons of the tumour. The results of the laboratory-animal experiments indicate that in vivo 31P NMR spectroscopy could be applied in the clinic in order to establish betime the response of tumours on therapy. In ch. 6 initial experiences with clinical NMR spectroscopy of human breast cancer are described. The results indicate that by 31P NMR spectroscopy malignant breast tissues can be discerned from normal breast tissues, following radiotherapy and subsequent tumour regression, in the spectrum of the tumorous region an intense PCr signal developed which appeared to reflect a metabolic change in the tumous itself. 177 refs.; 27 figs.; 6 tabs

  14. Hyperpolarized 13C MR for Molecular Imaging of Prostate Cancer

    OpenAIRE

    Wilson, David M.; Kurhanewicz, John

    2014-01-01

    Hyperpolarization using dissolution dynamic nuclear polarization has emerged as a versatile method to dramatically improve the MR signal of low-sensitivity nuclei. This technique facilitates the study of real-time metabolism in vitro and in vivo using 13C-enriched substrates and has been applied to numerous models of human disease. In particular, several mechanisms underlying prostate cancer have been interrogated using hyperpolarized 13C MR spectroscopy. This review highlights key metabolic ...

  15. Mechanisms of action of (meth)acrylates in hemolytic activity, in vivo toxicity and dipalmitoylphosphatidylcholine (DPPC) liposomes determined using NMR spectroscopy.

    Science.gov (United States)

    Fujisawa, Seiichiro; Kadoma, Yoshinori

    2012-01-01

    We investigated the quantitative structure-activity relationships between hemolytic activity (log 1/H(50)) or in vivo mouse intraperitoneal (ip) LD(50) using reported data for α,β-unsaturated carbonyl compounds such as (meth)acrylate monomers and their (13)C-NMR β-carbon chemical shift (δ). The log 1/H(50) value for methacrylates was linearly correlated with the δC(β) value. That for (meth)acrylates was linearly correlated with log P, an index of lipophilicity. The ipLD(50) for (meth)acrylates was linearly correlated with δC(β) but not with log P. For (meth)acrylates, the δC(β) value, which is dependent on the π-electron density on the β-carbon, was linearly correlated with PM3-based theoretical parameters (chemical hardness, η; electronegativity, χ; electrophilicity, ω), whereas log P was linearly correlated with heat of formation (HF). Also, the interaction between (meth)acrylates and DPPC liposomes in cell membrane molecular models was investigated using (1)H-NMR spectroscopy and differential scanning calorimetry (DSC). The log 1/H(50) value was related to the difference in chemical shift (ΔδHa) (Ha: H (trans) attached to the β-carbon) between the free monomer and the DPPC liposome-bound monomer. Monomer-induced DSC phase transition properties were related to HF for monomers. NMR chemical shifts may represent a valuable parameter for investigating the biological mechanisms of action of (meth)acrylates.

  16. NMR spectroscopy, Hammett correlations and biological activity of some Schiff bases derived from piperonal

    Energy Technology Data Exchange (ETDEWEB)

    Echevarria, Aurea [Universidade Federal Rural do Rio de Janeiro, Itaguai, RJ (Brazil). Dept. de Quimica; Nascimento, Maria da Graca; Geronimo, Vanilde [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Quimica; Miller, Joseph [Paraiba Univ., Joao Pessoa, PB (Brazil); Giesbrecht, Astrea [Sao Paulo Univ., SP (Brazil). Inst. de Ciencias Biomedicas

    1999-07-01

    A series of eleven Schiff Bases have been synthesized. They were obtained by condensation of piperonal (3,4-methylenedioxybenzaldehyde) with the corresponding aromatic primary amines. Their {sup 1}H and {sup 13}C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the substituent constants ({sigma}{sub p}, {sigma}R e {sigma}I) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-{alpha}) and C-1{sup '}, showing a more significant resonance effect on chemical shifts. The chemical shifts for C-4{sup '} were highly affected by substituent effects, especially for halogens in the expected direction. Their biological activity against microorganisms has also been measured and significant activity was showed against Epidermophyton floccosum. The biological activity did not give a reasonable relationship with electronic effects. (author)

  17. NMR spectroscopy, Hammett correlations and biological activity of some Schiff bases derived from piperonal

    International Nuclear Information System (INIS)

    A series of eleven Schiff Bases have been synthesized. They were obtained by condensation of piperonal (3,4-methylenedioxybenzaldehyde) with the corresponding aromatic primary amines. Their 1H and 13C-NMR spectra have been obtained and the Hammett correlations including chemical shifts and the substituent constants (σp, σR e σI) were studied. Linear and bilinear significant correlations were observed for iminic carbon (C-α) and C-1', showing a more significant resonance effect on chemical shifts. The chemical shifts for C-4' were highly affected by substituent effects, especially for halogens in the expected direction. Their biological activity against microorganisms has also been measured and significant activity was showed against Epidermophyton floccosum. The biological activity did not give a reasonable relationship with electronic effects. (author)

  18. 15N NMR spectroscopy of Pseudomonas cytochrome c-551

    International Nuclear Information System (INIS)

    15N-1H correlation spectroscopy with detection at the 1H frequency has been used at natural abundance to detect nitrogen nuclei bonded to protons in the ferrocytochrome c-551 from Pseudomonas aeruginosa (ATCC 19429). Side-chain aromatic nitrogen, main-chain amides, and side-chain amides have been assigned to specific residues by comparison to previous proton assignments. Assignment ambiguities arising from overlap in the proton dimension have been resolved by examining spectra as a function of temperature and pH. Nitrogen chemical shifts are reported at pH 4.6 and 9.4 and three temperatures, 32, 50, and 60 degree C. Significant differences arise from the observed protein shifts and expected shifts in the random coil polypeptide

  19. Site-specific {sup 13}C content by quantitative isotopic {sup 13}C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst [Firmenich SA, Corporate R and D Division, P.O. Box 239, 1211 Geneva 8 (Switzerland); Gilbert, Alexis; Yamada, Keita [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Yoshida, Naohiro [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Pagelot, Alain [Bruker Biospin SAS, 34 rue de l‘Industrie, 67166 Wissembourg Cedex (France); Moskau, Detlef; Moreno, Aitor [Bruker Biospin AG, Industriestrasse 26, 8117 Fällanden (Switzerland); Schleucher, Jürgen [Department of Medical Biochemistry and Biophysics, Umeå University, S-90187 Umeå (Sweden); Reniero, Fabiano; Holland, Margaret; Guillou, Claude [European Commission, Joint Research Centre – Institute for Health and Consumer Protection, via E. Fermi 2749, I-21027 Ispra (Italy); Silvestre, Virginie; Akoka, Serge [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France); Remaud, Gérald S., E-mail: gerald.remaud@univ-nantes.fr [EBSI team, Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), University of Nantes-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3 (France)

    2013-07-25

    Graphical abstract: -- Highlights: •First ring test on isotopic {sup 13}C NMR spectrometry. •Evaluation of the intra- and inter-variability of the NMR spectrometers used. •Definition of a protocol for qualification of the performance of the spectrometer. -- Abstract: Isotopic {sup 13}C NMR spectrometry, which is able to measure intra-molecular {sup 13}C composition, is of emerging demand because of the new information provided by the {sup 13}C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic {sup 13}C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular {sup 13}C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic {sup 13}C NMR was then assessed on vanillin from three different origins associated with specific δ{sup 13}C{sub i} profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ{sup 13}C{sub i} in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.

  20. 1-Magnesiotetrahydroisoquinolyloxazolines as Chiral Nucleophiles in Stereoselective Additions to Aldehydes: Auxiliary Optimization, Asymmetric Synthesis of (+)-Corlumine, (+)-Bicuculline, (+)-Egenine, and (+)-Corytensine, and Preliminary (13)C NMR Studies of 1-Lithio- and 1-Magnesiotetrahydroisoquinolyloxazolines.

    Science.gov (United States)

    Gawley, Robert E.; Zhang, Pingsheng

    1996-11-15

    Transmetalation of 1-lithiotetrahydroisoquinolyloxazolines with magnesium halides affords Grignard reagents that add to aldehydes with up to 80% selectivity for one of the four possible diastereomeric products. An oxazoline chiral auxiliary derived from camphor provides an optimal blend of diastereoselectivity and isomer separability. Synthetic applications of the optimal auxiliary, patterned after a literature approach in the racemic series, comprise an improved (formal) synthesis of bicuculline, egenine, and corytensine, as well as an efficient synthesis of corlumine. Preliminary NMR studies show that both 1-lithio- and 1-magnesiotetrahydroisoquinolyloxazolines are dynamic mixtures in THF solution at low temperatures. The barrier to pyramidal inversion of the secondary Grignard reagent is in the 9.8-10.1 kcal/mol range, while an upper limit of about 8.2 kcal/mol can be assigned to the barrier to the organolithium inversion. PMID:11667797