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Sample records for 13c nmr studies

  1. 13C NMR studies of the molecular flexibility of antidepressants

    The solution dynamics of a series of clinically potent antidepressants have been investigated by measuring 13C NMR relaxation parameters. Correlation times and internal motional rates were calculated from spin-lattice relaxation times and nuclear Overhauser effects for the protonated carbons in mianserin, imipramine-like antidepressants, and amitriptyline-like antidepressants. These data were interpreted in terms of overall molecular tumbling, internal rotations, and inherent flexibility of these structures. Of particular interest was the conformational variability of the tricyclic nucleus of the tricyclic antidepressants, where the data indicated a fivefold difference in mobility of the dimethylene bridge of imipramine-like antidepressants relative to amitriptyline-like compounds. The implications of such a difference in internal motions is discussed in relation to previous NMR studies and to the reported differences in pharmacological activity of these antidepressants

  2. 13C CPMAS NMR Studies of Anthocyanidins and their Glucosides

    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)

  3. Utilization of lysine {sup 13}C-methylation NMR for protein-protein interaction studies

    Hattori, Yoshikazu; Furuita, Kyoko [Osaka University, Institute for Protein Research (Japan); Ohki, Izuru, E-mail: i-ooki@bs.naist.jp [Nara Institute of Science and Technology (NAIST), Graduate School of Biological Sciences (Japan); Ikegami, Takahisa [Osaka University, Institute for Protein Research (Japan); Fukada, Harumi [Osaka Prefecture University, Graduate School of Life and Environmental Sciences (Japan); Shirakawa, Masahiro [Kyoto University, Graduate School of Engineering (Japan); Fujiwara, Toshimichi; Kojima, Chojiro, E-mail: kojima@protein.osaka-u.ac.jp [Osaka University, Institute for Protein Research (Japan)

    2013-01-15

    Chemical modification is an easy way for stable isotope labeling of non-labeled proteins. The reductive {sup 13}C-methylation of the amino group of the lysine side-chain by {sup 13}C-formaldehyde is a post-modification and is applicable to most proteins since this chemical modification specifically and quickly proceeds under mild conditions such as 4 Degree-Sign C, pH 6.8, overnight. {sup 13}C-methylation has been used for NMR to study the interactions between the methylated proteins and various molecules, such as small ligands, nucleic acids and peptides. Here we applied lysine {sup 13}C-methylation NMR to monitor protein-protein interactions. The affinity and the intermolecular interaction sites of methylated ubiquitin with three ubiquitin-interacting proteins were successfully determined using chemical-shift perturbation experiments via the {sup 1}H-{sup 13}C HSQC spectra of the {sup 13}C-methylated-lysine methyl groups. The lysine {sup 13}C-methylation NMR results also emphasized the importance of the usage of side-chain signals to monitor the intermolecular interaction sites, and was applicable to studying samples with concentrations in the low sub-micromolar range.

  4. Utilization of lysine 13C-methylation NMR for protein–protein interaction studies

    Chemical modification is an easy way for stable isotope labeling of non-labeled proteins. The reductive 13C-methylation of the amino group of the lysine side-chain by 13C-formaldehyde is a post-modification and is applicable to most proteins since this chemical modification specifically and quickly proceeds under mild conditions such as 4 °C, pH 6.8, overnight. 13C-methylation has been used for NMR to study the interactions between the methylated proteins and various molecules, such as small ligands, nucleic acids and peptides. Here we applied lysine 13C-methylation NMR to monitor protein–protein interactions. The affinity and the intermolecular interaction sites of methylated ubiquitin with three ubiquitin-interacting proteins were successfully determined using chemical-shift perturbation experiments via the 1H–13C HSQC spectra of the 13C-methylated-lysine methyl groups. The lysine 13C-methylation NMR results also emphasized the importance of the usage of side-chain signals to monitor the intermolecular interaction sites, and was applicable to studying samples with concentrations in the low sub-micromolar range.

  5. 13C-NMR studies of membrane lipid-protein interactions upon protein heat denaturation

    Spinach chloroplast membranes were studied by natural abundance carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy in their normal state and after heat denaturation of membrane proteins. The membrane proteins were denaturated by raising the temperature of the sample to 67degC for 5 minutes. Line-broadening of 13C-NMR resonances arising from the 1st (carbonyl), 7th, 9th and 12th carbon atom of fatty-acyl chains at these locations, obviously caused by changes in interactions between membrane lipids and proteins upon heat denaturation of membrane proteins. (author). 7 refs.; 1 fig

  6. Studies and characterization of in natura and benzylated sisal by using CPMAS 13C NMR

    Delignificated and benzylated sisal fibers were characterized by CPMAS 13 C NMR. In this study were analyzed the structure of the fiber before and after chemical treatments via delignification and benzylation processes. We observed that after delignification of sisal fiber, cellulose chains become more disordered and exposed which increases benzylation reaction efficiency. However, for not delignificated fibers their constituents decreases benzylation reaction efficiency. (author)

  7. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    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.

  8. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    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.  ……

  9. (13)C NMR Studies, Molecular Order, and Mesophase Properties of Thiophene Mesogens.

    Veeraprakash, B; Lobo, Nitin P; Narasimhaswamy, T

    2015-12-01

    Three-ring mesogens with a core comprising thiophene linked to one phenyl ring directly and to the other via flexible ester are synthesized with terminal alkoxy chains to probe the mesophase properties and find the molecular order. The phenyl thiophene link in the core offers a comparison of the mesophase features with the molecular shape of the mesogen. The synthesized mesogens display enantiotropic polymesomorphism and accordingly nematic, smectic A, smectic C and smectic B mesophases are perceived depending upon the terminal chain length. For some of the homologues, monotropic higher order smectic phases such as smectic F and crystal E are also witnessed. The existence of polymesomorphism are originally observed by HOPM and DSC and further confirmed by powder X-ray diffraction studies. For the C8 homologue, high resolution solid state (13)C NMR spectroscopy is employed to find the molecular structure in the liquid crystalline phase and using the 2D SLF technique, the (13)C-(1)H dipolar couplings are extracted to calculate the order parameter. By comparing the ratio of local order of thiophene as well as phenyl rings, we establish the bent-core shape of the mesogen. Importantly, for assigning the carbon chemical shifts of the core unit of aligned C8 mesogen, the (13)C NMR measured in mesophase of the synthetic intermediate is employed. Thus, the proposed approach addresses the key step in the spectral assignment of target mesogens with the use of (13)C NMR data of mesomorphic intermediate. PMID:26551439

  10. Study of xanthates reaction from cellulose and polypeptides by 13 C NMR in the solid state

    This work has aimed to study chemical reactions of p-nitro benzyl cellulose xanthate (CelXNB) and 2,4-dinitrophenyl cellulose xanthate (CelXDNP) with amines, which produced cellulose thio carbamates. These compounds were characterized and identified by 13 C NMR in the solid state. The following reactions were also studied: CelXNB and poly alanine, CelXNB and lysozyme, CelXDNP and poly alanine, and CelXDNP and lysozyme. Then, their NMR spectra have been presented and analysed

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

    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

  12. Host-guest interactions in fluorinated polymer electrolytes: A 7Li-13C NMR study

    Mustarelli, P.; Quartarone, E.; Capiglia, C.; Tomasi, C.; Ferloni, P.; Magistris, A.

    1999-08-01

    Gel-type electrolytes based on fluorinated polymers are of interest for electrochemical devices. We present a 7Li-13C solid-state NMR and modulated differential scanning calorimetry (MDSC) study of gel electrolytes based on a copolymer poly(vinylidene fluoride) (PVdF)-hexafluoropropylene (HFP) activated with a nonaqueous solution ethylene carbonate (EC)-propylene carbonate (PC)-LiN(CF3SO2)2. We show that the narrowing of the Li lineshape is decoupled from the glass transition. The behavior of the longitudinal relaxation times, T1, confirms that the host polymer matrix simply behaves like a quasiinert cage for the solution. These results are confirmed by 13C NMR at the magic angle (MAS) data, which show that the presence of the polymer does not significantly affect the chemical shift changes induced in the EC/PC carbons by the imide salt.

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

    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. Significantly lower values (∼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 13C NMR measurement of plasma [13C]glucose isotopomer populations. The finding of isotopomer populations of three adjacent 13C atoms at glucose C-4 (13C3-13C4-13C5) 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 ∼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 [13C]glucose formation from a trace amount of [U-13C]fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism

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

    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.

  15. An efficient procedure for studying pectin structure which combines limited depolymerization and 13C NMR

    A protocol for partial thermally-induced depolymerization of differently methoxylated pectin samples is described. The resulting macromolecules have been fully characterized with various complementary techniques, such as size exclusion chromatography (SEC), potentiometry, viscometry and 13C NMR. Optimum conditions afford samples at 50-80% yield with weight-average molecular weights in the 4 to 20 kDa range. The major fraction of these polysaccharides adopts the random-coil conformation and such samples are suitable for 13C NMR structural studies at room temperature. The methoxyl distributions of two apple pectin samples with a degree of esterification (DE) between 54 and 74% and a citrus pectin (DE, 72%) were shown to be random in nature, whereas that of a lightly methoxylated apple pectin (DE 39%) was partially blockwise. The carbon relaxation parameters of the depolymerized pectins attain asymptotic values for MW > 4 kDa. The MW values estimated from intrinsic viscosity data with the Mark-Houwink relationship reported for native pectins are in good agreement with those obtained by either end-group analysis (NMR) or SEC. Thus, all the physicochemical data indicate that the secondary structure of the isolated chains of depolymerized pectin is closely related to that of the parent polymers. Finally, pectinmethylesterase activity towards the depolymerized pectins was similar to that of the untreated samples. (orig.)

  16. An efficient procedure for studying pectin structure which combines limited depolymerization and {sup 13}C NMR

    Catoire, L.; Herve du Penhoat, C. [Dept. de Chimie, Ecole Normale Superieure, Paris (France); Goldberg, R.; Pierron, M. [Laboratoire d`enzymologie en Milieu Structure, Institut Jacques Monod, Paris (France); Morvan, C. [Faculte des Sciences, Universite de Rouen, Mont-Saint-Aignan (France)

    1998-04-01

    A protocol for partial thermally-induced depolymerization of differently methoxylated pectin samples is described. The resulting macromolecules have been fully characterized with various complementary techniques, such as size exclusion chromatography (SEC), potentiometry, viscometry and {sup 13}C NMR. Optimum conditions afford samples at 50-80% yield with weight-average molecular weights in the 4 to 20 kDa range. The major fraction of these polysaccharides adopts the random-coil conformation and such samples are suitable for {sup 13}C NMR structural studies at room temperature. The methoxyl distributions of two apple pectin samples with a degree of esterification (DE) between 54 and 74% and a citrus pectin (DE, 72%) were shown to be random in nature, whereas that of a lightly methoxylated apple pectin (DE 39%) was partially blockwise. The carbon relaxation parameters of the depolymerized pectins attain asymptotic values for M{sub W} > 4 kDa. The M{sub W} values estimated from intrinsic viscosity data with the Mark-Houwink relationship reported for native pectins are in good agreement with those obtained by either end-group analysis (NMR) or SEC. Thus, all the physicochemical data indicate that the secondary structure of the isolated chains of depolymerized pectin is closely related to that of the parent polymers. Finally, pectinmethylesterase activity towards the depolymerized pectins was similar to that of the untreated samples. (orig.) With 6 figs., 4 tabs., 27 refs.

  17. Estimation of glucose carbon recycling in children with glycogen storage disease: A 13C NMR study using [U-13C]glucose

    A stable isotope procedure to estimate hepatic glucose carbon recycling and thereby elucidate the mechanism by which glucose is produced in patients lacking glucose 6-phosphatase is described. A total of 10 studies was performed in children with glycogen storage disease type I (GSD-I) and type III (GSD-III) and control subjects. A primed dose-constant nasogastric infusion of D-[U-13C]glucose or an infusion diluted with nonlabeled glucose solution was administered following different periods of fasting. Hepatic glucose carbon recycling was estimated from 13C NMR spectra. The values obtained for GSD-I patients coincided with the standard [U-13C]glucose dilution curve. These results indicate that the plasma glucose of GSD-I subjects comprises only a mixture of 99% 13C-enriched D-[U-13C]glucose and unlabeled glucose but lacks any recycled glucose. Significantly different glucose carbon recycling values were obtained for two GSD-III patients in comparison to GSD-I patients. The results eliminate a mechanism for glucose production in GSD-I children involving gluconeogenesis. However, glucose release by amylo-1,6-glucosidase activity would result in endogenous glucose production of non-13C-labeled and nonrecycled glucose carbon, as was found in this study. In GSD-III patients gluconeogenesis is suggested as the major route for endogenous glucose synthesis. The contribution of the triose-phosphate pathway in these patients has been determined

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

    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.

  19. Solid state 13 C NMR quantitative study of wood tar pitches

    In this work, solid-state 13 C NMR is used with other techniques to characterize Eucalyptus tar pitches and to follow their polymerization reactions. The pitches are the residues of distillation (about 50% m;m) of the tar generated in Eucalyptus slow pyrolysis for charcoal production in metal industry

  20. Recent advances in the application of 13C and 15N NMR spectroscopy to soil organic matter studies

    Nuclear magnetic resonance (NMR) spectroscopy has been applied to many studies in soil science, geochemistry, and environmental science. In recent years, the study of soil organic matter (SOM) using NMR techniques has progressed rapidly. NMR spectroscopy has been used to study chemical changes of SOM during decomposition, and also of soil extract fractions such as humic acid and fulvic acid. NMR spectroscopy of soils has improved rapidly in recent years with the introduction of pre-treatment and particle-size fractionation. In addition to routine liquid- and solid-state 13C NMR applications, 15N NMR spectra of natural abundant samples have been reported, but 15N-enriched material is more convenient to use due to the low natural abundance of 15N. Some newly developed NMR techniques have also been utilised, such as 2-dimensional NMR spectroscopy and improved 1H NMR techniques. These are reviewed and commented on in this paper. Copyright (2000) CSIRO Publishing

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

    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 the...

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

    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...

  3. 13C-NMR study of polymer networks obtained by γ-irradiation

    The purpose of this study is the investigation of the γ-induced structural modification in ethylene-propylene (E-P) type rubbers. The studied elastomers have the same content of propylene, but EPDM includes 3.5% EBN, which decreases its radiation stability, so that the easiest cleavage happens on the diene site. The effect of γ-irradiation consists in coupling the free radicals and/or bridge formation between macromolecules. The direct consequences of radical reactions can be observed by gel content, changes in propylene concentration and distribution of (CH2)n units in initial and irradiated materials, the last two parameters being determined by 13C-NMR spectroscopy. The dose gel (dose value at which gel starts to be formed) is higher in EPR copolymers than in EPDM, due to the greater stability of the former elastomers. On the other hand, the propylene content and the distribution of various (CH2)n units, with n=1-6, evaluated by 13C-NMR spectra of CDCl3 swollen elastomers can be well correlated with the gel content for irradiated samples. Thus, the copolymer presents higher propylene content than the terpolymer within the same dose range. This behavior can be ascribed to diene effect, which leads to a greater rate of network formation, i.e., to higher crosslink density. The higher the propylene content, the lower the gel amount. The 13C-NMR determinations of the content of various (CH2)n units reveal a rather similar sequential distribution for both nonirradiated materials. The largest difference between (CH2)n distribution for the two materials occurs for medium dose values, because the crosslinking rate exceeds the scission one. However, at higher doses the scission process is prevalent. The free radicals are not able to reform the initial backbones due to higher concentration of molecular hydrogen as radiolysis by-product. Again, a similar distribution of (CH2)n units in both materials is observed. A multivariate statistical analysis of the irradiated

  4. Simple, efficient protocol for enzymatic synthesis of uniformly 13C, 15N-labeled DNA for heteronuclear NMR studies.

    Masse, J.E.; Bortmann, P; Dieckmann, T.; Feigon, J

    1998-01-01

    The use of uniformly 13C,15N-labeled RNA has greatly facilitated structural studies of RNA oligonucleotides by NMR. Application of similar methodologies for the study of DNA has been limited, primarily due to the lack of adequate methods for sample preparation. Methods for both chemical and enzymatic synthesis of DNA oligonucleotides uniformly labeled with 13C and/or 15N have been published, but have not yet been widely used. We have developed a modified procedure for preparing uniformly 13C,...

  5. 2H and 13C tracer studies of ethanol metabolism by Fourier transform 13C[2H, 1H] NMR difference spectroscopy

    A novel form of NMR difference spectroscopy has been developed to monitor low levels of deuterium incorporation in steroids resulting from ethanol metabolism. Ethanol specifically labeled with 13C and/or 2H was administered to bile fistula rats, and bile acids were collected, derivatized and separated. Subtracting 13C [1H] spectra from 13C[2H,1H] spectra of such samples, where the brackets imply complete noise decoupling of the indicated nuclei, results in difference spectra. These spectra display 13C resonances only from 13C spins which are J-coupled to 2H spins. Particular sites and extents of 2H incorporation along the steroid skeletons could thus be evaluated and compared with GC-MS analysis. A practical lower limit of approximately 20 nanomoles of 13C--2H couples could be observed using this technique, through use of sample microcells, quadrature detection and long-term signal averaging

  6. 13C-NMR assignment, structure, and dynamics of deoxyoligonucleotides

    The unique spectral properties of 13C-NMR for studying nucleic acids and some of the important features of 13C-NMR in oligonucleotide studies are demostrated. The main difficulty in studying oligonucleotides by 13C-NMR and recent improvements in NMR instrumentation and advances in oligonucleotide synthesis are presented. The high resolution 13C-NMR spectra, T1 relaxation times and NOEs were measured for duplex of the self-complementary oligo-DNAs: d(CG)3 and d(GGTATACC) are studied. The target of this study is to developed a systematic 13C-NMR spectral assignment and to investigate the structure and dynamics of these two sequences by this techniques. (M.J.C.)

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

    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.

  8. 13C and 31P NMR [Nuclear Magnetic Resonance] studies of prostate tumor metabolism

    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

  9. 13C magic angle spinning NMR study of CO adsorption on Ru-exchanged zeolite Y

    Three types of adsorbed carbon monoxide are observed on Ru-Y zeolite by 13C magic angle spinning NMR: linear, bridged, and dicarbonyl CO. Samples exposed to CO at room temperature exhibit only linear and dicarbonyl species. At higher adsorption temperature bridged species are formed and a relative increase in dicarbonyl adsorption is observed. A smaller percentage of linear species is produced at high temperature. The electronic environments of linearly bonded CO are more diverse than those of bridging and dicarbonyl moieties. CO2 is formed over Ru-Y zeolite upon initial exposure of the catalyst to CO at room temperature, apparently through reaction with unreduced metal oxide. 20 references, 2 figures, 1 table

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

    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.

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

    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....

  12. 31P and 13C-NMR studies of the phosphorus and carbon metabolites in the halotolerant alga, Dunaliella salina

    The intracellular phosphorus and carbon metabolites in the halotolerant alga Dunaliella salina adapted to different salinities were monitored in living cells by 31P- and 13C-nuclear magnetic resonance (NMR) spectroscopy. The 13C-NMR studies showed that the composition of the visible intracellular carbon metabolites other than glycerol is not significantly affected by the salinity of the growth medium. The T1 relaxation rates of the 13C-glycerol signals in intact cells were enhanced with increasing salinity of the growth medium, in parallel to the expected increase in the intracellular viscosity due to the increase in intracellular glycerol. The 31P-NMR studies showed that cells adapted to the various salinities contained inorganic phosphate, phosphomonoesters, high energy phosphate compounds, and long chain polyphosphates. In addition, cells grown in media containing up to 1 molar NaCl contained tripolyphosphates. The tripolyphosphate content was also controlled by the availability of inorganic phosphate during cell growth. Phosphate-depleted D. salina contained no detectable tripolyphosphate signal. Excess phosphate, however, did not result in the appearance of tripolyphosphate in 31P-NMR spectra of cells adapted to high (>1.5 molar NaCl) salinities

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

    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)

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

    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

  15. Retrobiosynthetic NMR studies with 13C-labeled glucose. Formation of gallic acid in plants and fungi

    The biosynthesis of gallic acid was studied in cultures of the fungus Phycomyces blakesleeanus and in leaves of the tree Rhus typhina. Fungal cultures were grown with [1-13C]glucose or with a mixture of unlabeled glucose and [U-13C6]glucose. Young leaves of R. typhina were kept in an incubation chamber and were supplied with a solution containing a mixture of unlabeled glucose and [U-13C6]glucose via the leaf stem. Isotope distributions in isolated gallic acid and aromatic amino acids were analyzed by one-dimensional 1H and 13C NMR spectroscopy. A quantitative analysis of the complex isotopomer composition of metabolites was obtained by deconvolution of the 13C13C coupling multiplets using numerical simulation methods. This approach required the accurate analysis of heavy isotope chemical shift effects in a variety of different isotopomers and the analysis of long range 13C13C coupling constants. The resulting isotopomer patterns were interpreted using a retrobiosynthetic approach based on a comparison between the isotopomer patterns of gallic acid and tyrosine. The data show that both in the fungus and in the plant all carbon atoms of gallic acid are biosynthetically equivalent to carbon atoms of shikimate. Notably, the carboxylic group of gallic acid is derived from the carboxylic group of an early intermediate of the shikimate pathway and not from the side chain of phenylalanine or tyrosine. It follows that the committed precursor of gallic acid is an intermediate of the shikimate pathway prior to prephenate or arogenate, most probably 5-dehydroshikimate. A formation of gallic acid via phenylalanine, the lignin precursor, caffeic acid, or 3,4, 5-trihydroxycinnamic acid can be ruled out as major pathways in the fungus and in young leaves of R. typhina. The incorporation of uniformly 13C-labeled glucose followed by quantitative NMR analysis of isotopomer patterns is suggested as a general method for biosynthetic studies. As shown by the plant experiment, this

  16. Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

    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

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

    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.

  18. Spectral density mapping at multiple magnetic fields suitable for 13C NMR relaxation studies

    Kadeřávek, Pavel; Zapletal, Vojtěch; Fiala, Radovan; Srb, Pavel; Padrta, Petr; Přecechtělová, Jana Pavlíková; Šoltésová, Mária; Kowalewski, Jozef; Widmalm, Göran; Chmelík, Josef; Sklenář, Vladimír; Žídek, Lukáš

    2016-05-01

    Standard spectral density mapping protocols, well suited for the analysis of 15N relaxation rates, introduce significant systematic errors when applied to 13C relaxation data, especially if the dynamics is dominated by motions with short correlation times (small molecules, dynamic residues of macromolecules). A possibility to improve the accuracy by employing cross-correlated relaxation rates and on measurements taken at several magnetic fields has been examined. A suite of protocols for analyzing such data has been developed and their performance tested. Applicability of the proposed protocols is documented in two case studies, spectral density mapping of a uniformly labeled RNA hairpin and of a selectively labeled disaccharide exhibiting highly anisotropic tumbling. Combination of auto- and cross-correlated relaxation data acquired at three magnetic fields was applied in the former case in order to separate effects of fast motions and conformational or chemical exchange. An approach using auto-correlated relaxation rates acquired at five magnetic fields, applicable to anisotropically moving molecules, was used in the latter case. The results were compared with a more advanced analysis of data obtained by interpolation of auto-correlated relaxation rates measured at seven magnetic fields, and with the spectral density mapping of cross-correlated relaxation rates. The results showed that sufficiently accurate values of auto- and cross-correlated spectral density functions at zero and 13C frequencies can be obtained from data acquired at three magnetic fields for uniformly 13C -labeled molecules with a moderate anisotropy of the rotational diffusion tensor. Analysis of auto-correlated relaxation rates at five magnetic fields represents an alternative for molecules undergoing highly anisotropic motions.

  19. Acetylcholinesterase-catalyzed acetate - water oxygen exchange studied by 13C-NMR

    The kinetics of the oxygen exchange reaction between [l-13C,18O2]acetate and H216O catalyzed by homogeneous acetyl-cholinesterase from the electric eel, Electrophorus electricus, was studied using the 18O-isotope-induced shift on 13C-nuclear magnetic resonance spectra. Pseudo-first-order rate constants for the exchange reactions were determined at pH values from 4.5 to 8. The exchange reaction exhibits a maximum at pH 5.8. The apparent catalytic rate constant for the exchange reaction is 102 to 104 times smaller than that for the deacylation of the acetyl-enzyme intermediate over the pH range tested. Oxygen exchange occurs by a random sequential pathway rather than by multiple (coupled) exchange. The inhibition of acetylcholinesterase by sodium acetate showed a sigmoidal dependence on pH, with K/sub i/ increasing 2.5 orders of magnitude over the pH range. Protonation of an active site residue having an apparent pKa of 6.8 is associated with an increase in acetate binding. Deacylation also exhibits a sigmoidal dependence on [H+]. The experimental data fits titration curves with inflection points at 5.0 +/- 0.3 and 6.7 +/-0.1. Results support the role of histidine in acetylation of the active site serine, but the conjugate base of another active site residue with a pKa of 5.0 appears necessary for maximal catalytic activity in both the deacylation and exchange reactions

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

    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)

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

    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.

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

    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.

  3. 13C/31P NMR studies on the role of glucose transport/phosphorylation in human glycogen supercompensation.

    Price, T B; Laurent, D; Petersen, K F

    2003-05-01

    This study measured muscle glycogen during a 7-day carbohydrate loading protocol. Twenty healthy subjects (12 male, 8 female) performed 1 hr treadmill/toe-raise exercise immediately before a 3-day low carbohydrate (LoCHO) diet (20 % carbohydrate, 60 % fat, 20 % protein). On day 3 they repeated the exercise and began a 4-day high carbohydrate (HiCHO) diet (90 % carbohydrate, 2 % fat, 8 % protein). The order of administration of the diet was reversed in a subpopulation (n = 3). Interleaved natural abundance 13C/ 31P NMR spectra were obtained before and immediately after exercise, and each day during the controlled diets in order to determine concentrations of glycogen (GLY), glucose-6-phosphate (G6P), and muscle pH. Following exercise, muscle GLY and pH were reduced (p supercompensation. PMID:12784164

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

    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℃.

  5. Structure and dynamics of poly(ethylene- co-1,5-hexadiene) as studied by solid state 13C NMR and quantum chemical calculations

    Kurosu, Hiromichi; Yamamoto, Yuuri; Fujikawa, Aki; Kawabata, Emika; Sone, Masato; Naga, Naofumi

    2009-03-01

    Poly(ethylene- co-1,5-hexadiene) with 1,5-hexadiene (HD) contents of 1.8, 8.1, 9.7 and 20.3% was prepared by copolymerization of ethylene and HD involving intermolecular cyclization. Higher-order structures and dynamics of these samples were studied by solid state NMR and quantum chemistry. The 13C solid state NMR spectra and 13C spin-lattice relaxation time ( T1) of the samples were measured. The observed 13C CP/MAS and PST/MAS NMR spectra for all samples were decomposed into six peaks. The cyclopentane units incorporated in the main chain of polyethylene affected not only the crystalline structure but also the noncrystalline structure. This causes a trans-rich conformation in the noncrystalline region. Even in the melt-quenched samples, incorporation of the cyclopentane structure into the polyethylene chain suppresses the increase in the gauche structure in the noncrystalline region. Based on the 13C chemical shift of the methylene carbon, the low cyclopentane content sample assumes an orthorhombic crystal structure, and the high cyclopentane content samples assume a hexagonal-type chain packing. 13C spin-lattice relaxation times show that the crystalline region of the low cyclopentane content sample has two regions with different mobility, although the high cyclopentane content samples have only one region with a high mobility for each peak. Furthermore, quantum chemical calculations for the 13C NMR shieldings were carried out for precise assignment of the peaks.

  6. 13C chemical shift anisotropies for carbonate ions in cement minerals and the use of 13C, 27Al and 29Si MAS NMR in studies of Portland cement including limestone additions

    13C isotropic chemical shifts and chemical shift anisotropy parameters have been determined for a number of inorganic carbonates relevant in cement chemistry from slow-speed 13C MAS or 13C(1H) CP/MAS NMR spectra (9.4 T or 14.1 T) for 13C in natural abundance. The variation in the 13C chemical shift parameters is relatively small, raising some doubts that different carbonate species in Portland cement-based materials may not be sufficiently resolved in 13C MAS NMR spectra. However, it is shown that by combining 13C MAS and 13C(1H) CP/MAS NMR carbonate anions in anhydrous and hydrated phases can be distinguished, thereby providing valuable information about the reactivity of limestone in cement blends. This is illustrated for three cement pastes prepared from an ordinary Portland cement, including 0, 16, and 25 wt.% limestone, and following the hydration for up to one year. For these blends 29Si MAS NMR reveals that the limestone filler accelerates the hydration for alite and also results in a smaller fraction of tetrahedrally coordinated Al incorporated in the C-S-H phase. The latter result is more clearly observed in 27Al MAS NMR spectra of the cement–limestone blends and suggests that dissolved aluminate species in the cement–limestone blends readily react with carbonate ions from the limestone filler, forming calcium monocarboaluminate hydrate. -- Highlights: •13C chemical shift anisotropies for inorganic carbonates from 13C MAS NMR. •Narrow 13C NMR chemical shift range (163–171 ppm) for inorganic carbonates. •Anhydrous and hydrated carbonate species by 13C MAS and 13C(1H) CP/MAS NMR. •Limestone accelerates the hydration for alite in Portland – limestone cements. •Limestone reduces the amount of aluminium incorporated in the C-S-H phase

  7. Direct 13C NMR Detection in HPLC Hyphenation Mode

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

    2012-01-01

    is indubitable in simplifying structural elucidations. In the current study, we demonstrated direct (13)C NMR detection of triterpenoids from a Ganoderma lucidum extract in hyphenation mode. The combined advantage of a cryogenically cooled probe, miniaturization, and multiple trapping enabled the...

  8. 11B, 13C-NMR study of the complex formation of phenylboronate with catechol and L-dopa

    In the solution of phenylboronic acid and either catechol or L-dopa at various pH, the equilibrium between phenylboronate anion and catechol or L-dopa to form the anionic complex has been demonstrated by the existence of 11B-NMR signals for the complex and either phenylboronate anion or phenylboronic acid. By the pH dependence of the 11B-NMR chemical shift of phenylboronate-phenylboronic acid solution, the ionization constant of phenylboronic acid (pKa) has been estimated as 8.90. By the 11B-NMR spectra at pH below 7, the complex formation constant, log K, has been obtained as 4.5 for catechol, and as 4.6 for L-dopa. The 13C-NMR spectra have also demonstrated the complex formations, but in the pH 8 and 9 solution of phenylboronic acid and L-dopa, the 13C-NMR signal of carbonyl carbon of L-dopa disappeared. (author)

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

    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

  10. 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

    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.

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

    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

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

    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)

  13. Proton exchange and temperature studies of pyrazole in dimethyl-d6 sulfoxide by 13C NMR

    The 13C NMR shifts of all the carbons in pyrazole have been observed at room temperature. This paper reports the kinetic data available from the temperature-induced collapse of the C-3, C-5 NMR peaks. ΔG2+ similarly ordered 7.0 kcal/mol, and ΔS2+ similarly ordered -25.0 cal/deg for the virtual tautomerism of pyrazole in SO-d6. Temperature-induced 13C DM shofts for the solvent and for pyrazole were also determined to be +1.47 x 10-3 and +2.0 x 10-3 ppM/deg for C-4 and the center of the C-3, C-5 peaks, respectively. The solvent shift for 13C with temperature is +11.59 +- 10-3 ppM/deg for the CD3 in DM SO-d6 and +3.22 x 10-3 ppM/deg for the deuterium in Me2SO-d6. Rapid exchange of pyrazole observed earlier by several workers in the solvent Me2SO-d6 is attributed to acid impurities present in previous samples. 3 tables

  14. 1H MAS, 13C CP/MAS, and 2H NMR spectra studies of piperidinium p-chlorobenzoate

    Anomalous H/D isotope effects were detected in the 1H MAS NMR spectra of piperidinium p-chlorobenzoate (C5H10NH 2+⋅ ClC6H4COO − ) upon deuterium substitution of hydrogen atoms which form two kinds of N-H⋯O H-bonds in the crystal; in contrast to these spectra, only slight chemical shifts were recorded in 13C CP/MAS NMR spectra. 2H NMR spectrum of the deuterated sample show quadrupole coupling constants of 148 and 108 kHz, and reveal that there are a few motions contributing to the electric-field modulation of the 2H nucleus. The 1H MAS NMR spectra of piperidinium p-chlrobenzoate-d16 (C5D10ND 2+⋅ ClC6D4COO − ) and -d14 (C5D10NH 2+⋅ ClC6D4COO − ) revealed that the change in the envelope is caused by chemical shifts of each signal upon deuteration. Calculations based on the density-functional-theory showed that the N-H distance along the crystallographic a-axis mainly contributes to the anomalous isotope effects on 1H MAS NMR envelopes.

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

    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)

  16. Morphological study of chitin from Xiphopenaeus kroyeri exoskeletons by using atomic force microscopy (AFM) and CPMAS 13 C NMR

    A sample of α chitin was isolated from exoskeletons of Xiphopenaeus kroyeri. This sample ws dissolved in phosphoric acid and recovered as a fibrous precipitate. Atomic force microscopy was used in noncontact mode to obtain images of the native chitin sample. Different morphological features were observed, including rigid rod crystals 200-300 nm wide. Solid state 13 C NMR techniques were used to investigate chitin samples, and revealed molecular order in both samples. The differences observed in the proton spin-lattice relaxation times in the rotating frame, TH1p were attributed to the formation of hydrogen bonds in preferential sites in the samples. (author)

  17. Acid-base equilibrium in aqueous solutions of 1,3-dimethylbarbituric acid as studied by 13C NMR spectroscopy

    Gryff-Keller, A.; Kraska-Dziadecka, A.

    2011-12-01

    13C NMR spectra of 1,3-dimethylbarbituric acid in aqueous solutions of various acidities and for various solute concentrations have been recorded and interpreted. The spectra recorded at pH = 2 and below contain the signals of the neutral solute molecule exclusively, while the ones recorded at pH = 7 and above only the signals of the appropriate anion, which has been confirmed by theoretical GIAO-DFT calculations. The signals in the spectra recorded for solutions of pH acid-base equilibrium. The kinetic data determined this way have been used to clarify the mechanisms of these processes. The numerical analysis has shown that under the investigated conditions deprotonation of the neutral solute molecules undergoes not only via a simple transfer of the C-H proton to water molecules but also through a process with participation of the barbiturate anions. Moreover, the importance of tautomerism, or association, or both these phenomena for the kinetics of the acid-base transformations in the investigated system has been shown. Qualitatively similar changes of 13C NMR spectra with the solution pH variation have been observed for the parent barbituric acid.

  18. Morphological study of chitin from Xiphopenaeus kroyeri exoskeletons by using atomic force microscopy (AFM) and CPMAS {sup 13} C NMR; Estudo morfologico de quitina da exocuticula de Xiphopenaeus kroyeri por AFM e por CPMAS {sup 13} C NMR

    Silva, K.M.; Tavares, M.I.; Andrade, C.T. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas; Simao, R.A. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Metalurgica e de Materiais

    1999-07-01

    A sample of {alpha} chitin was isolated from exoskeletons of Xiphopenaeus kroyeri. This sample ws dissolved in phosphoric acid and recovered as a fibrous precipitate. Atomic force microscopy was used in noncontact mode to obtain images of the native chitin sample. Different morphological features were observed, including rigid rod crystals 200-300 nm wide. Solid state {sup 13} C NMR techniques were used to investigate chitin samples, and revealed molecular order in both samples. The differences observed in the proton spin-lattice relaxation times in the rotating frame, T{sup H1}{sub p} were attributed to the formation of hydrogen bonds in preferential sites in the samples. (author)

  19. Interactions of D-cellobiose with selected chloride salts: A 13C NMR and FT-IR study

    Amarasekara, Ananda S.; Wiredu, Bernard

    2016-04-01

    The interactions of cellulose model compound D-cellobiose with chloride salts of Zn2 +, Ca2 +, Li+, Sn2 +, La3 +, Mg2 +, K+ and NH4+ were evaluated by measuring the 13C NMR chemical shift changes (Δδ) of the disaccharide due to the addition of salts in D2O. The KCl and NH4Cl showed similar Δδ changes due to interactions only with the Cl- anion. Whereas other chloride salts showed interactions with both cation and anion. Among these salts the total interactions are in the order: Zn2 + > Sn2 + > Li+ > Ca2 + ~ La3 + > Mg2 +. The FT-IR spectra of D-cellobiose-chloride salt 1:2 mixtures also indicate that KCl and NH4Cl interacts similarly with D-cellobiose in the solid state.

  20. 13C MAS NMR studies of the effects of hydration on the cell walls of potatoes and Chinese water chestnuts.

    Tang, H; Belton, P S; Ng, A; Ryden, P

    1999-02-01

    13C NMR with magic angle spinning (MAS) has been employed to investigate the cell walls of potatoes and Chinese water chestnuts over a range of hydration levels. Both single-pulse excitation (SPEMAS) and cross-polarization (CPMAS) experiments were carried out. Hydration led to a substantial increase in signal intensities of galactan and galacturonan in the SPEMAS spectra and a decrease in line width, implying mobilization in the backbone and side chains of pectin. In CPMAS spectra of both samples, noncellulose components showed signal loss as hydration increased. However, the signals of some galacturonan in the 3(1) helix configuration remained in the spectra even when the water content was as high as 110%. Cellulose was unaffected. It is concluded that the pectic polysaccharides experience a distribution of molecular conformations and mobility, whereas cellulose remained as typical rigid solid. PMID:10563925

  1. Fatty acid synthesis in Xylella fastidiosa: correlations between genome studies, 13C NMR data, and molecular models

    Xylella fastidiosa was the first plant pathogen to have its complete genome sequence elucidated. Routine database analyses suggested that two enzymes essential for fatty acid synthesis were missing, one of these is the holo-acyl-carrier-protein synthase. However, here we demonstrate, using 13C NMR spectroscopy, that X. fastidiosa is indeed able to synthesize fatty acids from acetate via an apparently conventional metabolic pathway. We further identify a gene product HetI, an alternative phosphopantetheinyl transferase, which we propose to fill the missing link. Homology modeling of HetI shows conservation of the Coenzyme A binding site suggesting it to be an active enzyme and reveals several interesting structural features when compared with the surfactin synthase-activating enzyme, on which the model was built. These include a simplified topology due to N- and C-terminal deletions and the observation of a novel serine ladder

  2. Uses of 1H NMR and 13C NMR spectroscopy in studies of phenylenedioxydiacetamides complexation with the cations of calcium and potassium in solution

    The complexation abilities and the coordination sites of 12 derivatives using infrared, 1HNMR and 13C NMR spectroscopy are analyzed. The spectroscopic results indicate that only the 1,2-phenylenedioxydiacetamides are suitable ligands; the 1,3 derivatives did not react. These ionophors 1-8 represent fourdentale chelating ligands where all four oxygen atmos are involved in bonds to the metal. Independent from its charge one cations is coordinate by two ionophors. (M.J.C.)

  3. 13C-NMR of diterpenes with pimarane skeleton

    The effect of substituent groups on the chemical shift of carbons using nuclear magnetic resonance spectra of carbon 13 (13C-NMR) is discussed. Diterpenes having pimarane skeleton, isolated from plants of Velloziaceae family are analysed. (ARHC)

  4. Study of the fusion reaction 13C+13C

    The fusion reaction 13C+13C has been studied, it must allow, by comparisons with the system 12C+13C already studied to determine how the presence of a supplementary nucleon in the interaction nuclei of the entrance channel affects the energy dependence of the reaction cross section. The reaction 13C+13C has been studied for incident energies E(CM)=3.05 - 6.88 MeV and no resonant structure seems to appear in the coulombian energies. The reaction products are identified by the energy of their gamma transition using a germanium detector situated at zero degree with respect to the incident beam at approximately 1 cm from the target

  5. 1H and 13C NMR and electrical conductivity studies on new ionic plastic crystals of tetraalkylammonium tetraethylborate

    Eight plastic crystals of the types NEtxMe(4-x)BEt4 and NEtyPr(4-y)BEt4 (x = 0-4, y = 1-3) were found in a new region of ionic plastic crystals. In this area, globular cations and anions are assembled by weak interactions. Based on the results of solid-state 1H and 13C nuclear magnetic resonance (NMR) measurements, it was revealed that the ions performed isotropic reorientations in the NEtxMe(4-x)BEt4 crystals (x = 0-4). Additionally, X-ray diffraction (XRD) of these compounds was able to identify the CsCl-type cubic structure. In contrast, the XRD reflections of NEtyPr(4-y)BEt4 (y = 1-3) could be successfully fitted by distorted cubic lattices (trigonal symmetry). The NMR line shapes observed in these compounds were explained by overall molecular motions with large amplitudes (pseudo-isotropic reorientations). Differential scanning calorimetry (DSC) spectra of NEtyPr(4-y)BEt4 (y = 1-3) showed a low entropy change (ΔSmp) of 6-8 J K-1 mol-1 at the melting point. Ionic diffusion was identified by electrical conductivity measurements of NEtxMe(4-x)BEt4 and NEtyPr(4-y)BEt4 (x = 0-4, y = 1-3). In the case of NPr4BEt4 crystals, ionic diffusion was also detected, although complex powder patterns and large ΔSmp values were observed by XRD and DSC measurements, respectively.

  6. 1H, 13C and 15N NMR spectral and X-ray structural studies of 2-arylsulfonylamino-5-chlorobenzophenones

    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)

  7. An in Vivo 13C NMR Analysis of the Anaerobic Yeast Metabolism of 1-13C-Glucose

    Giles, Brent J.; Matsche, Zenziwe; Egeland, Ryan D.; Reed, Ryan A.; Morioka, Scott S.; Taber, Richard L.

    1999-11-01

    A biochemistry laboratory experiment that studies the dynamics of the anaerobic yeast metabolism of 1-13C-D-glucose via NMR is described. Fleischmann's Active Dry yeast, under anaerobic conditions, produces primarily 2-13C-ethanol and some 1-13C-glycerol as end products. An experiment is described in which the yeast is subjected to osmotic shock from an increasing sodium chloride concentration. Under these conditions, the yeast increases the ratio of glycerol to ethanol. The experiment can be accomplished in a single laboratory period.

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

    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.

  9. A 1 H and 13 C NMR study of 2-methyl-4-N-phenyl amino quinazoline precursors

    2-substituted-4-phenyl amino quinazolines, synthetic intermediates of anti malarial, pesticides, herbicides and also inhibitors of the EGF receptor tyrosine kinase, are potentially useful as chemotherapeutic agents or the treatment of cancer. A few recent papers have described the synthesis and the corresponding biological activity studies of some derivates, and it has also been shown that their biological potency depends upon the substituent electronic properties in the 4-position of the quinazoline ring. Thus, it is expected that the biological activity can also be correlated with their Hydrogen-1 or Carbon-13 NMR chemical shift. This work reports the steps for both hydrogen-1 and carbon-13 NMR chemical shifts assignments for these compounds. Results are presented

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

    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.

  11. Assay of ascorbic acid in plants tissues, I: 1H and 13C NMR study of the complex between Cu(I) and 2,2'-biquinoline

    The Shieh's method, originally devised for the analysis of ascorbic acid (AsA) in pharmaceutical preparations and based on the reaction of this acid with Cu(I) and 2,2'-biquinoline, was adapted to determine AsA in biological samples and particularly in plant tissues. The proposed assay is compared with some current methods for AsA determination. Moreover the system Cu(I)-biquinoline is studied by 1H and 13C NMR spectroscopy, and a coordination model for the complex is proposed. (author). 12 refs., 4 figs., 2 tabs

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

    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.

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

    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...

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

    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.

  15. 13C NMR of diterpenes with isopimarane structure

    Several effects of the Δ sup(8(9)) double bond on the 13C NMR data of isopimarane diterpenoids are discussed, including chemical shifts and acetilation of the C-7 Hydroxyl radical on the above mentioned double bond. (C.L.B.)

  16. 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

    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

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

    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)

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

    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.

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

    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.

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

    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)

  1. 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

    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.

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

    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

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

    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...

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

    Urbanová, Martina; Šturcová, Adriana; Brus, Jiří; Beneš, Hynek; Skořepová, E.; Kratochvíl, B.; Čejka, J.; Šeděnková, Ivana; Kobera, Libor; Policianová, Olivia; Šturc, A.

    2013-01-01

    Roč. 102, č. 4 (2013), s. 1235-1248. ISSN 0022-3549 R&D Projects: GA ČR GPP106/11/P426 Institutional support: RVO:61389013 Keywords : trospium chloride * solid state NMR * factor analysis Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.007, year: 2013

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

    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.

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

    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.

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

    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.

  8. Monitoring electrochemical reactions in situ using steady-state free precession 13C NMR spectroscopy

    Highlights: • Analysis of electrochemical reaction in situ by 13C NMR spectroscopy was demonstrated. • 13C NMR signals are obtained in few minutes, using steady-state free precession (SSFP) pulse sequence. • The analysis is performed in standard NMR spectrometer. • KBDM can be an alternative to Fourier Transform to process SSFP signal. - Abstract: All attempts to use in situ13C NMR in spectroelectrochemical studies, using static cells and unlabeled substrates, have failed due to the very long average time (several hours). In this paper, we demonstrated that steady-state free precession (SSFP) pulse sequence can enhance signal to noise ratio and reduces the average time of 13C NMR signals by more than one order of magnitude. The results showed that each 13C NMR spectrum during the electrochemical reduction of 9-chloroanthracene, in a static cell, can be acquired in eleven minutes. This short averaging time allowed the analysis of the reaction every 30 min during 3 h. The phase and truncation anomalies present in SSFP spectra were minimized using Traff apodization function and Krylov basis diagonalization method (KBDM)

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

    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 CO2 at room temperature and high relative humidity and studied after one to 12 weeks. 29Si 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 Q3 and Q4 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 13C NMR. For C–A–S–H samples with Ca/Si = 1.0 and 1.5, 27Al 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)4 units in the amorphous silica phase. A small amount of penta-coordinated Al sites has also been identified in the silica phase

  10. 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

    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.

  11. Accurate quantitative 13C NMR spectroscopy: repeatability over time of site-specific 13C isotope ratio determination.

    Caytan, Elsa; Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Remaud, Gérald S

    2007-11-01

    The stability over time (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2 per thousand for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. PMID:17900175

  12. 2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: International collaborative study report

    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

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

    Thomas, Freddy; Jamin, Eric

    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 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 delta13C (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 thousand, and the average reproducibility (R) was 0.91 per thousand. 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 (delta13C and delta18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring delta18O were found to be similar to the values previously obtained for other methods applied to wine and

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

    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

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

    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.

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

    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.

  17. Effects of post-reactor functionalization on the phase behaviour of an ethylene-1-octene copolymer studied using solid-state high resolution 13C NMR spectroscopy.

    Calucci, Lucia; Cicogna, Francesca; Forte, Claudia

    2013-10-01

    The effects of post-reactor functionalization with naphthoate-TEMPO on the structure and morphology of an ethylene-1-octene copolymer were investigated by means of solid-state NMR techniques and DSC measurements. Selective (13)C MAS experiments allowed the orthorhombic and the monoclinic crystalline phases and two amorphous phases with different degree of mobility to be detected and quantified. (13)C and (1)H relaxation time measurements and spin diffusion experiments gave insight into the polymer dynamics within the different phases, the crystalline domain dimensions, and the rate of chain diffusion between amorphous and crystalline phases. Comparison of the results obtained for the pristine copolymer and the functionalized samples clearly indicated that the functionalization procedure causes redistribution within the crystalline and the amorphous phases with no relevant change in the degree of crystallinity or in the crystalline domain average size, and slows down chain diffusion. PMID:23942957

  18. 13C NMR spectra of trimethylene oxide and sulphide

    The 13C NMR spectra of trimethylene oxide and trimethylene sulphide have been recorded and analysed as second-order spectra. The values of all the C-H coupling constants with their signs are reported. The signs of the C-H coupling constants in trimethylene oxide were determined by selective irradiation experiments and theoretical calculations, while in trimethylene sulphide the signs were obtained directly from the analysis. The one-bond C-H coupling constants are approximately 3 Hz greater in trimethylene oxide than in trimethylene sulphide, while the absolute values of the two-bond and three-bond coupling constants, 2Jsub(cβH) and 3Jsub(CαH), are bout 1 Hz greater in the latter molecule. (orig.)

  19. 13 C and 31 P NMR use in phosphinite synthesis and rhodium cationic catalysts accompaniment

    Several studies on rigid cyclic frameworks have been developed recently. This work shows the use of 13 C and 31 P NMR analysis for identifying and characterizing the molecular structures of phosphinites, thiophosphinites and rhodium catalysts. The phosphinites were synthesized and rhodium complexes prepared from them, aiming the catalysts synthesis for hydrogenation processes. Synthesizing phosphinites and thiophosphinites, alcohols on their racemic form were used, therefore, the catalysts were obtained as diasteroisomers. 13 C and 31 P NMR data are discussed in details and chemical shifts are also analysed

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

    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.

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

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

    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)

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

    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.

  4. Accurate measurements of 13C-13C distances in uniformly 13C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    Application of sets of 13C-13C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important 13C-13C distances in uniformly 13C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl (13C′) and aliphatic (13Caliphatic) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly 13C,15N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of 13C′-13Caliphatic distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform 13C,15N-labeling on the FGAIL fragment

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

    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

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

    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

  7. 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.

    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

  8. 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)

    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)

  9. Structural modifications of vitrinite and alginite concentrates during pyrolytic maturation at different heating rates. A combined infrared, sup 13 C NMR and microscopical study

    Schenk, H.J.; Witte, E.G.; Littke, R.; Schwochau, K. (Nuclear Research Centre (KFA) Juelich, Juelich (Germany, F.R.). Inst. of Petroleum and Organic Geochemistry (ICH-5))

    1990-01-01

    Immature vitrinite samples from a Miocene brown coal seam of western Germany (H/C 1.14, O/C 0.41) and alginite concentrates from a Tasmanite deposit of Australia (H/C 1.60, O/C 0.10) were pyrolyzed in a stream of argon at heating rates of 0.1 and 2.0{degree}C/min up to temperatures varying from 200 to 670{degree}C. The solid maceral residues were subjected to elemental and microscopical analysis and studied by IR and {sup 13}C CP/MAS NMR spectroscopy with respect to structural modifications. The maximum pyrolytic weight loss amounts to 60% of the initial organic matter in the case of vitrinite and to 85% for alginite, the onset of degradation reactions being shifted to higher temperatures with increasing rate of heating. Both infrared and NMR spectra of the vitrinite samples indicate a rapid decomposition of the cellulose component upon heating whereas lignin related structures such as aromatic ether linkages remain remarkably stable. The main hydrocarbon release from vitrinite occurs at very early evolution stages (T{sub max} 296{degree}C, R{sub m} 0.20% at 0.1{degree}C/min; T{sub max} 337{degree}C, R{sub m} 0.23% at 2.0{degree}C/min). Hydrocarbon generation from alginite requires higher temperatures (T{sub max} 388 and 438{degree}C) and is completed within a distinctly narrower temperature range. The pronounced increase of vitrinite reflectance between 350 and 670{degree}C seems to be associated with a rather time-consuming reorganization of the residual organic material. The concomitant growth of polyaromatic units is illustrated by the increasing intensity ratio of the aromatic ring stretching vibration bands at 1600 and 1500 cm{sup -1}. These reactions are moreover marked by increasing loss of phenolic oxygen and by increasing conversion of aliphatic carbon into fixed aromatic carbon. 50 refs, 8 figs., 1 tab.

  10. 13C NMR investigation of local motions involved in secondary relaxation of polymers

    Monnerie, Lucien

    The 13C NMR methods which can be used to study the local dynamics of solid samples through the cross-polarization and magic angle spinning technique are briefly reviewed. We present results obtained on solid polycycloalkyl methacrylates, polybutylene terephtalate, polystyrene and substituted polystyrenes and compare them with mechanical relaxation measurements.

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

    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.

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

    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

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

    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.

  14. The use of /sup 13/C-glucose and NMR to study cerebral carbohydrate metabolism in vivo in the rat and the rhesus monkey

    This report describes some preliminary work in the development of a method for the determination of the cerebral intermediary glucose metabolism in humans in vivo. The procedure makes use of specifically labeled [/sup 13/C]glucose and NMR and incorporates some of the theoretical considerations, equations and algorithms of a method the authors proposed in a recent publication for the determination of cerebral metabolism in humans in vivo using specifically labeled /sup 11/C-glucose and positron emission transverse tomography (PETT). Both the method for PETT and NMR make use of the enrichment of carbon atoms of glutamate in the brain with the label from intravenously administered isotopic glucose. Previously, the authors proposed a scheme for human cerebral metabolism of glucose in vivo which included in the tricarboxylic acid cycle (TCA) a small metabolically active pool of glutamate, γ-aminobutyrate and succinic semialdehyde. The small pool of glutamate in the TCA cycle was considered to be in slow equilibrium with a large metabolically inactive glutamate pool in the brain

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

    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

  16. 13C and 17O NMR binding constant studies of uranyl carbonate complexes in near-neutral aqueous solution. Yucca Mountain Project Milestone Report 3351

    Valuable structural information, much of it unavailable by other methods, can be obtained about complexes in solution through NMR spectroscopy. From chemical shift and intensity measurements of complexed species, NMR can serve as a species-specific structural probe for molecules in solution and can be used to validate thermodynamic constants used in geochemical modeling. Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy has been employed to study the speciation of uranium(VI) ions in aqueous carbonate solutions as a function of pH, ionic strength, carbonate concentration, uranium concentration, and temperature. Carbon-13 and oxygen-17 NMR spectroscopy were used to monitor the fractions, and hence thermodynamic binding constants of two different uranyl species U02(CO3)34- and (UO2)3(CO3)66- in aqueous solution. Synthetic buffer solutions were prepared under the ionic strength conditions used in the NMR studies in order to obtain an accurate measure of the hydrogen ion concentration, and a discussion of pH = -log(aH+) versus p[H] = -log[H+] is provided. It is shown that for quantitative studies, the quantity p[H] needs to be used. Fourteen uranium(VI) binding constants recommended by the OECD NEA literature review were corrected to the ionic strengths employed in the NMR study using specific ion interaction theory (SIT), and the predicted species distributions were compared with the actual species observed by multinuclear NMR. Agreement between observed and predicted stability fields is excellent. This establishes the utility of multinuclear NMR as a species-specific tool for the study of the actinide carbonate complexation constants, and serves as a means for validating the recommendations provided by the OECD NEA

  17. Hyperpolarized 13C NMR lifetimes in the liquid-state: relating structures and T1 relaxation times

    Parish, Christopher; Niedbalski, Peter; Hashami, Zohreh; Fidelino, Leila; Kovacs, Zoltan; Lumata, Lloyd

    Among the various attempts to solve the insensitivity problem in nuclear magnetic resonance (NMR), the physics-based technique dissolution dynamic nuclear polarization (DNP) is probably the most successful method of hyperpolarization or amplifying NMR signals. Using this technique, liquid-state NMR signal enhancements of several thousand-fold are expected for low-gamma nuclei such as carbon-13. The lifetimes of these hyperpolarized 13C NMR signals are directly related to their 13C spin-lattice relaxation times T1. Depending upon the 13C isotopic location, the lifetimes of hyperpolarized 13C compounds can range from a few seconds to minutes. In this study, we have investigated the hyperpolarized 13C NMR lifetimes of several 13C compounds with various chemical structures from glucose, acetate, citric acid, naphthalene to tetramethylallene and their deuterated analogs at 9.4 T and 25 deg C. Our results show that the 13C T1s of these compounds can range from a few seconds to more than 60 s at this field. Correlations between the chemical structures and T1 relaxation times will be discussed and corresponding implications of these results on 13C DNP experiments will be revealed. US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  18. 13C-NMR Data of Diterpenes Isolated from Aristolochia Species

    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.

  19. Performance evaluation of quantitative adiabatic (13)C NMR pulse sequences for site-specific isotopic measurements.

    Thibaudeau, Christophe; Remaud, Gérald; Silvestre, Virginie; Akoka, Serge

    2010-07-01

    (2)H/(1)H and (13)C/(12)C site-specific isotope ratios determined by NMR spectroscopy may be used to discriminate pharmaceutically active ingredients based on the synthetic process used in production. Extending the Site-specific Natural Isotope Fractionation NMR (SNIF-NMR) method to (13)C is highly beneficial for complex organic molecules when measurements of (2)H/(1)H ratios lead to poorly defined molecular fingerprints. The current NMR methodology to determine (13)C/(12)C site-specific isotope ratios suffers from poor sensitivity and long experimental times. In this work, several NMR pulse sequences based on polarization transfer were evaluated and optimized to measure precise quantitative (13)C NMR spectra within a short time. Adiabatic 180 degrees (1)H and (13)C pulses were incorporated into distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (INEPT) to minimize the influence of 180 degrees pulse imperfections and of off-resonance effects on the precision of the measured (13)C peak areas. The adiabatic DEPT sequence was applied to draw up a precise site-specific (13)C isotope profile of ibuprofen. A modified heteronuclear cross-polarization (HCP) experiment featuring (1)H and (13)C spin-locks with adiabatic 180 degrees pulses is also introduced. This sequence enables efficient magnetization transfer across a wide (13)C frequency range although not enough for an application in quantitative (13)C isotopic analysis. PMID:20527737

  20. Evaluation of natural rubber from IAC series clones by solid state 13C NMR

    Agronomic Institute (IAC) and EMBRAPA Agricultural Instrumentation (EMBRAPA/CNPDIA) have been studied Hevea species in order to increase the production of the natural rubber and to develop new clones more appropriated to Brazil's soil and climate. Structural characterization of natural rubber [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg.] from new clones of the IAC series (IAC 300, 301, 302, 303, 35, 40, and 56) and from RRIM 600 clone has been studied by high-resolution solid-state 13C NMR and by single pulse technique. The results have shown that the application of solid-state 13C NMR using the single pulse technique is a powerful tool to study natural rubber. The spectra obtained through this technique confirmed that natural rubber from all clones studied are cis-1,4-polyisoprene (author) form.(author)

  1. Early estrogen-induced metabolic changes and their inhibition by actinomycin D and cycloheximide in human breast cancer cells: 31P and 13C NMR studies

    Metabolic changes following estrogen stimulation and the inhibition of these changes in the presence of actinomycin D and cycloheximide were monitored continuously in perfused human breast cancer T47D clone 11 cells with 31P and 13C NMR techniques. The experiments were performed by estrogen rescue of tamoxifen-treated cells. Immediately after perfusion with estrogen-containing medium, a continuous enhancement in the rates of glucose consumption, lactate production by glycolysis, and glutamate synthesis by the Krebs cycle occurred with a persistent 2-fold increase at 4 hr. Pretreatment with either actinomycin D or cycloheximide, at concentrations known to inhibit mRNA and protein synthesis, respectively, and simultaneous treatment with estrogen and each inhibitor prevented the estrogen-induced changes in glucose metabolism. This suggested that the observed estrogen stimulation required synthesis of mRNA and protein. These inhibitors also modulated several metabolic activities that were not related to estrogen stimulation. The observed changes in the in vivo kinetics of glucose metabolism may provide a means for the early detection of the response of human breast cancer cells to estrogen versus tamoxifen treatment

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

    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.

  3. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    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

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

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

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

    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)

  7. sup(1)H, sup(13)C and sup(17)O NMR studies of cumene hydroperoxide coordination to Cr(AA)sub(3)

    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)

  8. 13C-NMR of forest soil lipids

    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 ...

  9. In vivo 13C MRS studies of carbohydrate metabolism

    The work described in this thesis was performed by the author, except where indicated, within the Magnetic Resonance Centre at the University of Nottingham during the period between October 1999 and October 2002. Although much is known about the major pathways of carbohydrate metabolism, there is still much to be learnt about the exact mechanisms of many of these pathways. Of particular interest is how these pathways are modified under different physiological conditions and in diseased states. 13C NMR spectroscopy provides a non-invasive means for studying carbohydrate metabolism in vivo, and the work presented within this thesis gives two such examples of this in human subjects. Natural abundance 13C NMR spectroscopy was used to measure glycogen levels in gastrocnemius muscle. The diurnal changes in response to mixed meals were measured in both type 2 diabetic subjects and age and weight matched controls. Metabolic studies were performed to complement the NMR measurements. The data obtained in these studies show the effect of the failure of muscle glucose storage upon post-prandial hyperglycaemia despite a supra-normal increase in plasma insulin in type 2 diabetes. 13C NMR spectroscopy was also used to study cerebral metabolism. Accumulation of 13C label into glutamate and glutamine following infusion of [113C] glucose allows the determination of the rates of the TCA cycle (FTCA) and neurotransmitter cycling (Fcyc). These rates were measured in the visual cortex under control and activated conditions. The increases seen in FTCA upon activation, together with the lack of label accumulation in lactate, suggest that cerebral glucose metabolism is oxidative, even during strong activation. No conclusion can be made as to whether or not a similar increase is seen in Fcyc due to the large associated errors in these values. (author)

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

    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)

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

    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)

  12. Heteronuclear NMR studies of cobalamins. 9. Temperature-dependent NMR of organocobalt corrins enriched in 13C in the organic ligand and the thermodynamics of the base-on/base-off reaction

    The synthesis of alkylcobinamides (RCbi) enriched in 13C in the organic axial ligand by standard reductive alkylation procedures from 13C-enriched alkyl halides has been shown to lead essentially exclusively to β-alkylcobamides (i.e., the organic ligand in the upper axial ligand position) by uv-visible and NMR spectroscopy and HPLC coupled with direct synthesis of 13CH3Cbi of known stereochemistry from 13C-enriched methylcobalamin (13CH3Cbl). The ionic strength dependence of the on/off pK/sub a/ of CH3Cbl, CH3CH2Cbl, and α-ribazole has also been investigated. Measurements of the relative 13C resonance frequency of 13CH3Cbl and 13CH3Cbi as a function of temperature at several ionic strengths have been used to investigate the thermodynamics of the base-on/base-off reaction of cobalamins. Additional evidence has thus been obtained for a previously detected species of base-off, but benzimidazole-deprotonated, cobalamin in which the benzimidazole B3 nitrogen atom is hydrogen-bonded to an e side chain N-H, and the thermodynamics of formation of this species have been evaluated. These results have been confirmed by similar measurements on mixtures of -OOC13CH2Cbl and -OOC13CH2Cbi. Although the new species is the predominant form (80-90%) of the base-off but benzimidazole-deprotonated cobalamins in solution at all ionic strengths, its presence has only a minor effect on the primary on/off equilibrium constants previously calculated for RCbl's. 45 references, 4 figures, 8 tables

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

    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

  14. 13C NMR spectra in the liquid and solid states

    Hrabal, R.; Brus, Jiří; Madronová, L.; Novák, František

    New York : Nova Science Publisher, 2011 - (Madronová, L.), s. 35-46 ISBN 978-1-61668-965-0. - ( Chemistry Research and Applications ) Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z60660521 Keywords : solid-state NMR * humic acids * soil Subject RIV: CD - Macromolecular Chemistry https://www.novapublishers.com/catalog/product_info.php?products_id=14700

  15. 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

    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.

  16. 13C NMR spectroscopy of methane adsorbed in SAPO-11 molecular sieve

    Koskela, Tuomas; Ylihautala, Mika; Vaara, Juha; Jokisaari, Jukka

    1996-10-01

    Static 13C and 13C-{ 1H} NMR spectra of carbon-13 enriched methane ( 13CH 4) adsorbed into SAPO-11 molecular sieve were recorded at variable temperatures. Moreover, the corresponding MAS NMR spectra were measured. These experiments reveal a temperature-dependent, anisotropic and asymmetric 13C nuclear shielding tensor. Ab initio model calculations of methane in the field of a positive point charge suggest that the deformation of the shielding tensor may be related to the interaction between the methane molecule and the charge-compensating protons. A comparison with existing Xe data is made.

  17. 13C solid-state NMR of gramicidin A in a lipid membrane.

    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...

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

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    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. PMID:27022916

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

    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.

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

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    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. PMID:27022916

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

    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.)

  2. Theoretical predictions of the two-dimensional solid-state NMR spectra: a case study of the 13C-1H correlations in metergoline

    Czernek, Jiří; Brus, Jiří

    2013-01-01

    Roč. 586, 24 October (2013), s. 56-60. ISSN 0009-2614 Institutional support: RVO:61389013 Keywords : NMR * shielding * metergoline Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.991, year: 2013

  3. Solid-state /sup 13/C NMR and X-ray diffraction of dermatan sulfate

    Winter, W.T.; Taylor, M.G.; Stevens, E.S.; Morris, E.R.; Rees, D.A.

    1986-05-29

    Dermatan sulfate in the solid state has been studied by /sup 13/C CP/MAS nmr and X-ray diffraction in order to establish the ring conformation of the L-iduronate moiety. The solid state nmr spectrum is similar to the solution spectrum obtained previously, indicating that a ring conformation at least approximating to /sup 1/C/sub 4/ predominates in the solid state. X-ray powder diffraction data from the same sample indicate the presence of the 8-fold helix form previously observed by fiber diffraction, and interpreted in terms of a /sup 4/C/sub 1/ ring form. A likely explanation of the results is that a distorted /sup 1/C/sub 4/ L-iduronate ring conformation, not considered in the initial X-ray analysis, may emerge to provide a satisfactory interpretation of all available physical-chemical data.

  4. Solid-state 13C NMR and X-ray diffraction of dermatan sulfate

    Dermatan sulfate in the solid state has been studied by 13C CP/MAS nmr and X-ray diffraction in order to establish the ring conformation of the L-iduronate moiety. The solid state nmr spectrum is similar to the solution spectrum obtained previously, indicating that a ring conformation at least approximating to 1C4 predominates in the solid state. X-ray powder diffraction data from the same sample indicate the presence of the 8-fold helix form previously observed by fiber diffraction, and interpreted in terms of a 4C1 ring form. A likely explanation of the results is that a distorted 1C4 L-iduronate ring conformation, not considered in the initial X-ray analysis, may emerge to provide a satisfactory interpretation of all available physical-chemical data

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

    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

  6. 1H, 13C and 15N NMR assignments of phenazopyridine derivatives.

    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

  7. 13C NMR spectra of the uranyl tricarbonate-bicarbonate system

    The 13C NMR identification of the uranyl tricarbonate complex (important in solution mining of U from ore and conventional carbonate leaching) is reported. The NMR spectra show the transition from slow to fast carbonate exchange between uranyl ion and bulk water in an accessible temperature range. The taller NMR peak at 162.31 ppM is frm HCO3- and the smaller peak at 168.86 ppM is from the uranyl tricarbonate complex

  8. Quantitative solid-state 13C NMR with signal enhancement by multiple cross polarization

    Johnson, Robert L.; Schmidt-Rohr, Klaus

    2014-02-01

    A simple new method is presented that yields quantitative solid-state magic-angle spinning (MAS) 13C NMR spectra of organic materials with good signal-to-noise ratios. It achieves long (>10 ms) cross polarization (CP) from 1H without significant magnetization losses due to relaxation and with a moderate duty cycle of the radio-frequency irradiation, by multiple 1-ms CP periods alternating with 1H spin-lattice relaxation periods that repolarize the protons. The new method incorporates previous techniques that yield less distorted CP/MAS spectra, such as a linear variation (“ramp”) of the radio-frequency field strength, and it overcomes their main limitation, which is T1ρ relaxation of the spin-locked 1H magnetization. The ramp of the radio-frequency field strength and the asymptotic limit of cross polarization makes the spectral intensity quite insensitive to the exact field strengths used. The new multiCP pulse sequence is a “drop-in” replacement for previous CP methods and produces no additional data-processing burden. Compared to the only reliable quantitative 13C NMR method for unlabeled solids previously available, namely direct-polarization NMR, the measuring time is reduced by more than a factor of 50, enabling higher-throughput quantitative NMR studies. The new multiCP technique is validated with 14-kHz MAS on amino-acid derivatives, plant matter, a highly aromatic humic acid, and carbon materials made by low-temperature pyrolysis.

  9. Preparation of partially 2H/13C-labelled RNA for NMR studies. Stereo-specific deuteration of the H5′′ in nucleotides

    Cromsigt, Jenny; Schleucher, Jürgen; Gustafsson, Tomas; Kihlberg, Jan; Wijmenga, Sybren

    2002-01-01

    An effective in vitro enzymatic synthesis is described for the production of nucleoside triphosphates (NTPs) which are stereo-specifically deuterated on the H5′′ position with high selectivity (>98%), and which can have a variety of different labels (13C, 15N, 2H) in other positions. The NTPs can subsequently be employed in the enzymatic synthesis of RNAs using T7 polymerase from a DNA template. The stereo-specific deuteration of the H5′′ immediately provides the stereo-specific assignment of...

  10. Synthesis and multinuclear (1H, 13C, 31P, 119Sn) NMR study of trimethyland; triphenyl-tin (IV) with cyclic dithiophosphate ligands

    Patricia García y García; Marcela López Cardoso; María del Carmen Pérez Redondo; Patricia Martínez Salas; Ave María Cotero Villegas; Raymundo Cea Olivares

    2004-01-01

    En este trabajo se informa la síntesis y caracterización; estructural de seis nuevos ditiofosfatos de trimetil- y trifenil-estaño (IV).; Los compuestos 1-6 fueron caracterizados por IR, EM IE y RMN multinuclear,; (1H, 13C, 19P y 119Sn). Los seis compuestos manifiestan un; comportamiento monomérico, con una penta-coordinación del átomo de; estaño y un comportamiento monometálico biconectivo de los ligantes.; Los compuestos 1-4 presentan en solución una rápida interconversión;...

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

    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

  12. 1 H and 13 C NMR of phenyl barbiturilidene

    The condensation of barbituric acids with aromatic aldehydes gives the phenyl barbiturilidenes, which are studied as intermediary compounds in the synthesis of new heterocyclic compounds for pharmaceutical use. One of the most characteristic reactions of these compounds is the Michael type addition reaction, in the exocyclic carbon-carbon double binding. The reaction with 2,4-di nitrophenyl hydrazine reaction is been used as a test of this type of reactivity, which supplies the respective hydrazone and barbituric acid. In this work, preliminary studies have been performed for establishing correlations between the Brown parameter (σ+), the chemical shifts (δ) of the barbiturilidene atoms involved in the reaction, and their reactivities

  13. Benchmarks for the 13C NMR chemical shielding tensors in peptides in the solid state

    Czernek, Jiří; Pawlak, Tomasz; Potrzebowski, Marek J.

    2012-02-01

    The benchmark set is proposed, which comprises 126 principal elements of chemical shielding tensors, and the respective isotropic chemical shielding values, of all 42 13C nuclei in crystalline Tyr-D-Ala-Phe and Tyr-Ala-Phe tripeptides with known, but highly dissimilar structures. These data are obtained by both the NMR measurements and the density functional theory in the pseudopotential plane-wave scheme. Using the CASTEP program, several computational strategies are employed, for which the level of agreement between calculations and experiment is established. This set is mainly intended for the validation of methods capable of predicting the 13C NMR parameters in solid-state systems.

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

    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

  15. Site-specific {sup 13}C content by quantitative isotopic {sup 13}C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

    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.

  16. 13C NMR spectral data and molecular descriptors to predict the antioxidant activity of flavonoids

    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 13C 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)

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

    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)

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

    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)

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

    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)

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

    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)

  1. Occurrence, biological activities and 13C NMR data of amides from Piper (Piperaceae

    Jeferson C. do Nascimento

    2012-01-01

    Full Text Available 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 13C 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.

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

    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)

  3. Determination of the DNA sugar pucker using 13C NMR spectroscopy

    Solid-state 13C NMR spectroscopy of a series of crystalline nucleosides and nucleotides allows direct measurement of the effect of the deoxyribose ring conformation on the carbon chemical shift. It is found that 3'-endo conformers have 3' and 5' chemical shifts significantly (5-10 ppm) upfield of comparable 3'-exo and 2'-endo conformers. The latter two conformers may be distinguished by smaller but still significant differences in the carbon chemical shifts at the C-2' and C-4' positions. High-resolution solid-state NMR of three modifications of fibrous calf thymus DNA shows that these trends are maintained in high-molecular-weight DNA and confirms that the major ring pucker in A-DNA is 3'-endo, while both B-DNA and C-DNA are largely 2'-endo. The data show that 13C NMR spectroscopy is a straightforward and useful probe of DNA ring pucker in both solution and the solid state

  4. 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

    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

  5. 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

    Sancheti, Harsh; Patil, Ishan; Kanamori, Keiko; Díaz Brinton, Roberta; Zhang, Wei; Lin, Ai-Ling; Cadenas, Enrique

    2014-01-01

    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 m...

  6. {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

    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

  7. Site-specific 13C content by quantitative isotopic 13C Nuclear Magnetic Resonance spectrometry: A pilot inter-laboratory study

    Graphical abstract: -- Highlights: •First ring test on isotopic 13C 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 13C NMR spectrometry, which is able to measure intra-molecular 13C composition, is of emerging demand because of the new information provided by the 13C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic 13C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular 13C 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 13C NMR was then assessed on vanillin from three different origins associated with specific δ13Ci 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 δ13Ci 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

  8. Direct detection of solanesol in tobacco by 1H and 13C magic angle spinning NMR

    1H and 13C NMR have been used to detect solanesol directly in tobacco without destroying or modifying the sample. Magic angle sample spinning was employed to remove the resonance line broadening due to variations of magnetic susceptibility within the sample. 13C line widths of ca . 10 Hz were obtained. The 1H MAS spectrum of tobacco allows the solanesol signals to be resolved from the broad signal of exchangeable protons. 13C spin-lattice relaxation times (T3) and nuclear Overhauser enhancements (NOE) of solanesol in chloroform solution, in intact tobacco, and as nest oil indicate that the polyisoprene chain motion in tobacco is restricted relative to the motion in solution but still sufficient to average out the dipolar couplings between protons and carbons. (author)

  9. Aspects of solid state 13C CPMAS NMR spectroscopy in coals from the Balkan peninsula

    ANDREAS GEORGAKOPOULOS

    2003-09-01

    Full Text Available The cross-polarized magic-angle-spinning NMR (CPMAS-NMR technique was used in this work to assess the carbon distribution in coals of different rank (peat, lignite, xylite, sub-bituminous coal from important deposits in Greece and Bulgaria. The technique is assumed to be only semiquantitative, due to a number of interferences, such as spinning side bands (SSB in the spectra, paramagnetic species in the samples, and low or remote protonation of aromatic carbons. The Bulgarian sub-bituminous coal shows the greatest amounts of aromatic structures. The lignite sample from the Drama basin, Northern Greece, is relatively unaltered and largely unweathered, and shows the greatest amounts of aliphatic groups. The 13C-NMR spectra of Pliocene lignites from endemic areas in Serbia and Montenegro and Bosnia, taken from published papers, show significantly more intense resonances for methoxyl, phenolic, and polysaccharide moieties compared to the Drama lignite NMR spectrum. Xylite reveals high contents of carbohydrates.

  10. Changes in chemical composition of litter during decomposition: a review of published 13C NMR spectra

    Cepáková, Šárka; Frouz, Jan

    2015-01-01

    Roč. 15, č. 3 (2015), s. 805-815. ISSN 0718-9516 Grant ostatní: GAJU(CZ) GAJU/04-146/2013P; GA ČR(CZ) GAP504/12/1288 Institutional support: RVO:60077344 Keywords : 13C CPMAS NMR * litter decomposition * litter quality * soil organic matter Subject RIV: DF - Soil Science Impact factor: 0.680, year: 2014

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

    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).

  12. 13C NMR and stereochestry of 1-β-phenylethylcyclohexanol derivatives obtained by synthesis

    1-β-Phenylethylcyclohexanol derivatives substituted in position 2 have been synthesized and analysed by 13C-NMR spectroscopy. Their stereochemistry have been considered as cis (hydroxyl in C-1 and substituent in C-2) which is in agreement with the pertinent literature. Derivatives obtained were 2-β-phenylethyl-2-allycyclohexanol, 1-β-phenylethyl-2-methylcyclohexanol, 7a-β-phenylethylperhy-drobenzo (b) furan, and 1-β-phenylethyl-2-β-hydroxyethylcyclohexanol. (author)

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

    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.

  14. 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

    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.

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

    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)

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

    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.

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

    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

  18. Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR, Theoretical and Microbiological Study of trans o-Coumaric Acid and Alkali Metal o-Coumarates

    Małgorzata Kowczyk-Sadowy

    2015-02-01

    Full Text Available This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR, Raman (FT-Raman, ultraviolet-visible (UV-VIS and nuclear magnetic resonance (1H- and 13C-NMR were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans.

  19. Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR), theoretical and microbiological study of trans o-coumaric acid and alkali metal o-coumarates.

    Kowczyk-Sadowy, Małgorzata; Świsłocka, Renata; Lewandowska, Hanna; Piekut, Jolanta; Lewandowski, Włodzimierz

    2015-01-01

    This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic) acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR), Raman (FT-Raman), ultraviolet-visible (UV-VIS) and nuclear magnetic resonance (1H- and 13C-NMR) were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT) using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans. PMID:25689641

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

    Highlights: • 1H NMR profilings of 718 wines were fused with stable isotope analysis data (SNIF-NMR, 18O, 13C). • 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 1H NMR to 99% for the fused data). • Independent component analysis was used as an alternative chemometric tool for classification. - Abstract: It is known that 1H 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 1H NMR profiles are fused with stable isotope (SNIF-NMR, 18O, 13C) data. Variable selection based on clustering of latent variables was performed on 1H 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 1H 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 1H NMR data alone in 82–89% respectively). Certain enhancement was obtained also for the year of vintage (from 88 to 97% for 1H NMR to 99% for the fused data), whereas in case of grape varieties improved models were not obtained. The combination of 1H 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

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

    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

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

    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

  3. 13C-NMR-Based Metabolomic Profiling of Typical Asian Soy Sauces

    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.

  4. Structural characterization of supramolecular assemblies by {sup 13}C spin dilution and 3D solid-state NMR

    Habenstein, Birgit; Loquet, Antoine; Giller, Karin; Becker, Stefan; Lange, Adam, E-mail: adla@nmr.mpibpc.mpg.de [Max Planck Institute for Biophysical Chemistry, Department of NMR-based Structural Biology (Germany)

    2013-01-15

    {sup 13}C spin diluted protein samples can be produced using [1-{sup 13}C] and [2-{sup 13}C]-glucose (Glc) carbon sources in the bacterial growth medium. The {sup 13}C spin dilution results in favorable {sup 13}C spectral resolution and polarization transfer behavior. We recently reported the combined use of [1-{sup 13}C]- and [2-{sup 13}C]-Glc labeling to facilitate the structural analysis of insoluble and non-crystalline biological systems by solid-state NMR (ssNMR), including sequential assignment, detection of long-range contacts and structure determination of macromolecular assemblies. In solution NMR the beneficial properties of sparsely labeled samples using [2-{sup 13}C]-glycerol ({sup 13}C labeled C{alpha} sites on a {sup 12}C diluted background) have recently been exploited to provide a bi-directional assignment method (Takeuchi et al. in J Biomol NMR 49(1):17-26, 2011 ). Inspired by this approach and our own recent results using [2-{sup 13}C]-Glc as carbon sources for the simplification of ssNMR spectra, we present a strategy for a bi-directional sequential assignment of solid-state NMR resonances and additionally the detection of long-range contacts using the combination of {sup 13}C spin dilution and 3D NMR spectroscopy. We illustrate our results with the sequential assignment and the collection of distance restraints on an insoluble and non-crystalline supramolecular assembly, the Salmonella typhimurium type III secretion system needle.

  5. 13C solution NMR spectra of poly(ether)urethanes. Technical memorandum

    The 13C solution nuclear magnetic resonance (NMR) spectra of the 15 poly(ether)urethanes are presented. The poly(urethane)s were prepared using one of two diisocyanates, either methylene diphenyl diisocyanate (MDI) or hexamethylene diisocyanate (HDI), one of five poly(ether glycol)s, poly(tetramethylene ether glycol) of molecular weight 650, 1000, or 1400, or poly(ethylene glycol) of molecular weight 600 or 1000, and one of three chain extenders, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, or diethylene glycol. These polymers were prepared as part of a modelling study to determine if Group Contribution Theory and Group Interaction Modelling could be used to predict dynamic mechanical properties of poly(ether)urethanes on the basis of the structural fragments in the polymers. The chemical shifts of the unique carbons in each of the poly(urethane)s are assigned. They can be used to unambiguously identify the diisocyanate/diol/poly(ether glycol) used to prepare the various polyurethanes. For some compounds the spectra show resonances for terminal hydroxyl substituted carbons. These could provide a method, under the right experimental conditions, to compare molecular weights of batches of the same polymer. (author)

  6. Experimental (X-ray, (13)C CP/MAS NMR, IR, RS, INS, THz) and Solid-State DFT Study on (1:1) Co-Crystal of Bromanilic Acid and 2,6-Dimethylpyrazine.

    Łuczyńska, Katarzyna; Drużbicki, Kacper; Lyczko, Krzysztof; Dobrowolski, Jan Cz

    2015-06-01

    A combined structural, vibrational spectroscopy, and solid-state DFT study of the hydrogen-bonded complex of bromanilic acid with 2,6-dimethylpyrazine is reported. The crystallographic structure was determined by means of low-temperature single-crystal X-ray diffraction, which reveals the molecular units in their native protonation states, forming one-dimensional infinite nets of moderate-strength O···H-N hydrogen bonds. The nature of the crystallographic forces, stabilizing the studied structure, has been drawn by employing the noncovalent interactions analysis. It was found that, in addition to the hydrogen bonding, the intermolecular forces are dominated by stacking interactions and C-H···O contacts. The thermal and calorimetric analysis was employed to probe stability of the crystal phase. The structural analysis was further supported by a computationally assisted (13)C CP/MAS NMR study, providing a complete assignment of the recorded resonances. The vibrational dynamics was explored by combining the optical (IR, Raman, TDs-THz) and inelastic neutron scattering (INS) spectroscopy techniques with the state-of-the-art solid-state density functional theory (DFT) computations. Despite the quasi-harmonic approximation assumed throughout the study, an excellent agreement between the theoretical and experimental data was achieved over the entire spectral range, allowing for a deep and possibly thorough understanding of the vibrational characteristics of the system. Particularly, the significant influence of the long-range dipole coupling on the IR spectrum has been revealed. On the basis of a wealth of information gathered, the recent implementation of a dispersion-corrected linear-response scheme has been extensively examined. PMID:25961154

  7. Temperature {sup 1}H, {sup 13}C, {sup 15}N NMR and CP/MAS {sup 15}N NMR spectra of benzotriazole derivatives - prototropic tautomerism; Widma temperaturowe {sup 1}H, {sup 13}C, {sup 15}N NMR oraz CP/MAS {sup 15}N NMR pochodnych benzotriazolu - tautomeria prototropowa

    Wiench, J.W.; Stefaniak, L. [Inst. Chemii Organicznej, Polska Akademia Nauk, Warsaw (Poland)

    1994-12-31

    The prototropic tautomerism in benzotriazole derivatives solutions has been investigated in different temperatures by means of {sup 1}H, {sup 13}C and {sup 15}N NMR and {sup 15}N CP/MAS NMR spectra. The ratio of different tautomeric forms and kinetics of proton exchange have been measured for the systems studied on the base of observed spectroscopic factors. 5 refs, 2 figs, 3 tabs.

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

    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.

  9. Solid-state NMR determination of sugar ring pucker in (13)C-labeled 2'-deoxynucleosides.

    van Dam, Lorens; Ouwerkerk, Niels; Brinkmann, Andreas; Raap, Jan; Levitt, Malcolm H.

    2002-01-01

    The H3'-C3'-C4'-H4' torsional angles of two microcrystalline 2'-deoxynucleosides, thymidine and 2'-deoxycytidine.HCl, doubly (13)C-labeled at the C3' and C4' positions of the sugar ring, have been measured by solid-state magic-angle-spinning nuclear magnetic resonance (NMR). A double-quantum heteronuclear local field experiment with frequency-switched Lee-Goldberg homonuclear decoupling was used. The H3'-C3'-C4'-H4' torsional angles were obtained by comparing the experimental curves with nume...

  10. (13) C-TmDOTA as versatile thermometer compound for solid-state NMR of hydrated lipid bilayer membranes.

    Umegawa, Yuichi; Tanaka, Yuya; Nobuaki, Matsumori; Murata, Michio

    2016-03-01

    Recent advances in solid-state nuclear magnetic resonance (NMR) techniques, such as magic angle spinning and high-power decoupling, have dramatically increased the sensitivity and resolution of NMR. However, these NMR techniques generate extra heat, causing a temperature difference between the sample in the rotor and the variable temperature gas. This extra heating is a particularly crucial problem for hydrated lipid membrane samples. Thus, to develop an NMR thermometer that is suitable for hydrated lipid samples, thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA) was synthesized and labeled with (13) C (i.e., (13) C-TmDOTA) to increase the NMR sensitivity. The complex was mixed with a hydrated lipid membrane, and the system was subjected to solid-state NMR and differential scanning calorimetric analyses. The physical properties of the lipid bilayer and the quality of the NMR spectra of the membrane were negligibly affected by the presence of (13) C-TmDOTA, and the (13) C chemical shift of the complex exhibited a large-temperature dependence. The results demonstrated that (13) C-TmDOTA could be successfully used as a thermometer to accurately monitor temperature changes induced by (1) H decoupling pulses and/or by magic angle spinning and the temperature distribution of the sample inside the rotor. Thus, (13) C-TmDOTA was shown to be a versatile thermometer for hydrated lipid assemblies. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26460094

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

    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.

  12. 13C NMR spectroscopy of amorphous hydrogenated carbon and amorphous hydrogenated boron carbide

    We report the 13C NMR spectrum of amorphous hydrogenated carbon and boron carbide. The amorphous hydrogenated carbon spectra consist primarily of an sp3 line at 40 ppm and an sp2 line at 140 ppm and are in reasonable agreement with the recent theoretical calculations of Mauri, Pfrommer, and Louie, but there are some notable discrepancies. The amorphous hydrogenated boron carbide spectra are very different from those of amorphous hydrogenated carbon, being dominated by one line at 15 ppm. We interpret this line as due to carbon bound in boron carbide icosahedra, because polycrystalline boron carbide with boron carbide icosahedra as the unit cell gives very similar NMR spectra. copyright 1999 The American Physical Society

  13. 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.

    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

  14. 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

    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.

  15. Carbonyl 13C NMR spectrum of basin pancreatic trypsin inhibitor: resonance assignments by selective amide hydrogen isotope labeling and detection of isotope effects on 13C nuclear shielding

    The carbonyl region of the natural abundance 13C nuclear magnetic resonance (NMR) spectrum of basic pancreatic trypsin inhibitor is examined, and 65 of the 66 expected signals are characterized at varying pH and temperature. Assignments are reported for over two-thirds of the signals, including those of all buried backbone amide groups with slow proton exchange and all side-chain carbonyl groups. This is the first extensively assigned carbonyl spectrum for any protein. A method for carbonyl resonance assignments utilizing amide proton exchange and isotope effects on nuclear shielding is described in detail. The assignments are made by establishing kinetic correlation between effects of amide proton exchange observed in the carbonyl 13C region with development of isotope effects and in the amide proton region with disappearance of preassigned resonances. Several aspects of protein structure and dynamics in solution may be investigated by carbonyl 13C NMR spectroscopy. Some effects of side-chain primary amide group hydrolysis are described. The main interest is on information about intramolecular hydrogen-bond energies and changes in the protein due to amino acid replacements by chemical modification or genetic engineering

  16. 1H and 13C NMR assignments for the glycans in glycoproteins by using 2H/13C-labeled glucose as a metabolic precursor

    In order to understand the role of the glycans in glycoproteins in solution, structural information obtained by NMR spectroscopy is obviously required. However, the assignment of the NMR signals from the glycans in larger glycoproteins is still difficult, mainly due to the lack of appropriate methods for the assignment of the resonances originating from the glycans. By using [U-13C6,2H7]glucose as a metabolic precursor, we have successfully prepared a glycoprotein whose glycan is uniformly labeled with 13C and partially with D at the sugar residues. The D to H exchange ratios at the C1-C6 positions of the sugar residues have been proven to provide useful information for the spectral assignments of the glycan in the glycoprotein. This is the first report on the residue-specific assignment of the anomeric resonances originating from a glycan attached to a glycoprotein by using the metabolic incorporation of hydrogen from the medium into a glycan labeled with [U-13C6,2H7]glucose

  17. Hydrothermal carbon from biomass: structural differences between hydrothermal and pyrolyzed carbons via 13C solid state NMR.

    Falco, Camillo; Perez Caballero, Fernando; Babonneau, Florence; Gervais, Christel; Laurent, Guillaume; Titirici, Maria-Magdalena; Baccile, Niki

    2011-12-01

    The objective of this paper is to better describe the structure of the hydrothermal carbon (HTC) process and put it in relationship with the more classical pyrolytic carbons. Indeed, despite the low energetic impact and the number of applications described so far for HTC, very little is known about the structure, reaction mechanism, and the way these materials relate to coals. Are HTC and calcination processes equivalent? Are the structures of the processed materials related to each other in any way? Which is the extent of polyaromatic hydrocarbons (PAH) inside HTC? In this work, the effect of hydrothermal treatment and pyrolysis are compared on glucose, a good model carbohydrate; a detailed single-quantum double-quantum (SQ-DQ) solid state (13)C NMR study of the HTC and calcined HTC is used to interpret the spectral region corresponding to the signal of furanic and arene groups. These data are compared to the spectroscopic signatures of calcined glucose, starch, and xylose. A semiquantitative analysis of the (13)C NMR spectra provides an estimation of the furanic-to-arene ratio which varies from 1:1 to 4:1 according to the processing conditions and carbohydrate employed. In addition, we formulate some hypothesis, validated by DFT (density functional theory) modeling associated with (13)C NMR chemical shifts calculations, about the possible furan-rich structural intermediates that occur in the coalification process leading to condensed polyaromatic structures. In combination with a broad parallel study on the HTC processing conditions effect on glucose, cellulose, and raw biomass (Falco, C.; Baccile, N.; Titirici, M.-M. Green Chem., 2011, DOI: 10.1039/C1GC15742F), we propose a broad reaction scheme and in which we show that, through HTC, it is possible to tune the furan-to-arene ratio composing the aromatic core of the produced HTC carbons, which is not possible if calcination is used alone, in the temperature range below 350 °C. PMID:22050004

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

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

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

    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.

  1. Solid state CP/MAS 13C n.m.r. analysis of particle size and density fractions of soil incubated with uniformly labelled 13C-glucose

    A soil incubated for 34 days in the absence (control) and presence (treated) of uniformly labelled 13C-glucose was dispersed using an ultrasonic probe and fractionated by sedimentation in water and a polytungstate solution of density 2.0 Mg m-3. Solid state CP/MAS 13C n.m.r. (cross polarization/magic angle spinning 13C nuclear magnetic resonance) spectroscopy was used to characterize the chemical structure of the native soil organic carbon and the residual substrate carbon in the fractions of the control and treated soils. To obtain quantitative results it was essential to determine the spin lattice relaxation time in a rotating frame of the individual carbon types in the spectra as the relaxation behaviour of the native organic material in the clay fraction was different from that of the residual substrate carbon. The residual substrate carbon was found to accumulate in predominantly alkyl and O-alkyl structures in both fractions. However, significant amounts of acetal and carboxyl carbon were also observed in the clay fraction. Little if any aromatic or phenolic carbon was synthesized by the soil microorganisms utilizing substrate carbon. Dipolar dephasing CP/MAS 13C n.m.r. experiments were also performed and allowed the proportion of each type of carbon which was protonated and nonprotonated to be estimated. Essentially all of the O-alkyl and acetal carbon, 25-40% of the aromatic carbon and 66-80% of the alkyl carbon was protonated in the fractions isolated from the treated soil. 24 refs., 4 figs., 2 tabs

  2. Glucose transport in human erythrocytes measured using 13C NMR spin transfer

    The authors present the results of a new NMR-based procedure for measuring the fast transmembrane exchange of D-[1-13C]glucose in human erythrocytes. The method relies on different rates of exchange between the α- and β-anomers of glucose inside and outside the cells; the rate outside the cells is greatly increased by the addition of mutarotase to the suspension. Theory is developed to describe nuclear-spin transfer in the present system and is used to analyse the data to yield estimates of transmembrane-exchange rate constants and their statistical uncertainties. For a total glucose concentration of 25.5 mmol/l at 400C the first order efflux rate constants for the α- and β-anomers were 1.20 ± 0.40 s-1 and 0.71 ± 0.30 s-1, respectively. 17 refs.; 4 figs

  3. Histidine side-chain dynamics and protonation monitored by 13C CPMG NMR relaxation dispersion

    The use of 13C 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 13C labeled histidine residues in plastocyanin (PCu) from Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for 13Cε1 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 15N backbone relaxation measurements. Compared to measurements of backbone nuclei, 13Cε1 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 13Cε1 dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains are discussed

  4. Evaluation of natural rubber from IAC series clones by solid state {sup 13}C NMR; Avaliacao da borracha natural de clones da serie IAC por {sup 13}C RMN no estado solido

    Martins, Maria A.; Moreno, Rogerio M.B.; Goncalves, Paulo S. [Instituto Agronomico de Campinas, SP (Brazil). Centro de Cafe e Plantas Tropicais. Programa Seringueira]. E-mails: paulog@iac.sp.gov.br; mariaalice@cnpdia.embrapa.br; Forato, Lucimara A.; Colnago, Luiz A.; Mattoso, Luiz H.C. [EMBRAPA Instrumentacao Agropecuaria, Sao Carlos, SP (Brazil)]. E-mail: colnago@cnpdia.embrapa.br; forato@cnpdia.embrapa.br; rogerio@cnpdia.embrapa.br; mattoso@cnpdia.embrapa.br; Job, Aldo E. [Universidade Estadual Paulista (UNESP), Presidente Prudente, SP (Brazil). Departamento de Fisica, Quimica e Biologia

    2005-07-01

    Agronomic Institute (IAC) and EMBRAPA Agricultural Instrumentation (EMBRAPA/CNPDIA) have been studied Hevea species in order to increase the production of the natural rubber and to develop new clones more appropriated to Brazil's soil and climate. Structural characterization of natural rubber [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg.] from new clones of the IAC series (IAC 300, 301, 302, 303, 35, 40, and 56) and from RRIM 600 clone has been studied by high-resolution solid-state {sup 13}C NMR and by single pulse technique. The results have shown that the application of solid-state {sup 13}C NMR using the single pulse technique is a powerful tool to study natural rubber. The spectra obtained through this technique confirmed that natural rubber from all clones studied are cis-1,4-polyisoprene (author) form.(author)

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

    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

  6. Characterization of a Mixture of CO2 Adsorption Products in Hyperbranched Aminosilica Adsorbents by (13)C Solid-State NMR.

    Moore, Jeremy K; Sakwa-Novak, Miles A; Chaikittisilp, Watcharop; Mehta, Anil K; Conradi, Mark S; Jones, Christopher W; Hayes, Sophia E

    2015-11-17

    Hyperbranched amine polymers (HAS) grown from the mesoporous silica SBA-15 (hereafter "SBA-15-HAS") exhibit large capacities for CO2 adsorption. We have used static in situ and magic-angle spinning (MAS) ex situ (13)C nuclear magnetic resonance (NMR) to examine the adsorption of CO2 by SBA-15-HAS. (13)C NMR distinguishes the signal of gas-phase (13)CO2 from that of the chemisorbed species. HAS polymers possess primary, secondary, and tertiary amines, leading to multiple chemisorption reaction outcomes, including carbamate (RnNCOO(-)), carbamic acid (RnNCOOH), and bicarbonate (HCO3(-)) moieties. Carbamates and bicarbonate fall within a small (13)C chemical shift range (162-166 ppm), and a mixture was observed including carbamic acid and carbamate, the former disappearing upon evacuation of the sample. By examining the (13)C-(14)N dipolar coupling through low-field (B0 = 3 T) (13)C{(1)H} cross-polarization MAS NMR, carbamate is confirmed through splitting of the (13)C resonance. A third species that is either bicarbonate or a second carbamate is evident from bimodal T2 decay times of the ∼163 ppm peak, indicating the presence of two species comprising that single resonance. The mixture of products suggests that (1) the presence of amines and water leads to bicarbonate being present and/or (2) the multiple types of amine sites in HAS permit formation of chemically distinct carbamates. PMID:26477882

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

    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

  8. Formation of 1:1 and 2:1 host-guest inclusion complexes of α-cyclodextrin with cycloalkanols: A 1H and 13C NMR spectroscopic study

    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.

  9. 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.

    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.

  10. Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises

    Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

    2012-01-01

    This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

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

    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

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

    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.

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

    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

  14. Brominated compounds from marine sponges of the genus Aplysina and a compilation of their 13C NMR spectral data.

    Lira, Narlize Silva; Montes, Ricardo Carneiro; Tavares, Josean Fechine; da Silva, Marcelo Sobral; da Cunha, Emidio V L; de Athayde-Filho, Petronio Filgueiras; Rodrigues, Luis Cezar; da Silva Dias, Celidarque; Barbosa-Filho, Jose Maria

    2011-01-01

    Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A), cavernicolins (B), hydroverongiaquinols (C), bromotyrosineketals (D), bromotyrosine lactone derivatives (E), oxazolidones (F), spiroisoxazolines (G), verongiabenzenoids (H), verongiaquinols (I), and dibromocyclohexadienes (J). A compilation of their (13)C NMR data is also part of the review. For this purpose 138 references were consulted. PMID:22163189

  15. Brominated Compounds from Marine Sponges of the Genus Aplysina and a Compilation of Their 13C NMR Spectral Data

    Jose Maria Barbosa-Filho

    2011-11-01

    Full Text Available Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A, cavernicolins (B, hydroverongiaquinols (C, bromotyrosineketals (D, bromotyrosine lactone derivatives (E, oxazolidones (F, spiroisoxazolines (G, verongiabenzenoids (H, verongiaquinols (I, and dibromocyclohexadienes (J. A compilation of their 13C NMR data is also part of the review. For this purpose 138 references were consulted.

  16. (1)H, (13)C and (15)N NMR assignments of a calcium-binding protein from Entamoeba histolytica.

    Verma, Deepshikha; Bhattacharya, Alok; Chary, Kandala V R

    2016-04-01

    We report almost complete sequence specific (1)H, (13)C and (15)N NMR assignments of a 150-residue long calmodulin-like calcium-binding protein from Entamoeba histolytica (EhCaBP6), as a prelude to its structural and functional characterization. PMID:26377206

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

    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

  18. Characterization of organic matter in sediment cores of the Todos os Santos Bay, Bahia, Brazil, by elemental analysis and 13C NMR

    Highlights: → The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by EA and 13C NMR. → This article reports a study of six sediment cores collected at different depths and regions. → The elemental profiles of cores suggest an abrupt change in the sedimentation regime, corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects. → The results presented illustrate several important aspects of environmental impact of human activity on this bay. - Abstract: The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by elemental analysis and 13C Nuclear Magnetic Resonance (13C NMR). This article reports a study of six sediment cores collected at different depths and regions of Todos os Santos Bay. The elemental profiles of cores collected on the eastern side of Frades Island suggest an abrupt change in the sedimentation regime. Autoregressive Integrated Moving Average (ARIMA) analysis corroborates this result. The range of depths of the cores corresponds to about 50 years ago, coinciding with the implantation of major onshore industrial projects in the region. Principal Component Analysis of the 13C NMR spectra clearly differentiates sediment samples closer to the Subae estuary, which have high contents of terrestrial organic matter, from those closer to a local oil refinery. The results presented in this article illustrate several important aspects of environmental impact of human activity on this bay.

  19. 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

    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

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

    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

  1. 13C NMR of methane in an AlPO4-11 molecular sieve: Exchange effects and shielding anisotropy

    Koskela, Tuomas; Ylihautala, Mika; Jokisaari, Jukka; Vaara, Juha

    1998-12-01

    13C NMR spectra of 13CH4 in an AlPO4-11 molecular sieve reveal exchange effects between adsorbed and nonadsorbed methane gas. An application of pulsed field gradients is introduced to decrease nonadsorbed and exchanging gas signals in order to extract the chemical shift anisotropy line shape of the adsorbed gas. The resulting 13C shielding anisotropy of methane is compared to existing value for methane in related SAPO-11 material. Less anisotropic shielding is observed in AlPO4-11, most likely due to the lack of charge-compensating cations.

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

    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...

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

    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

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

    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

  5. 13C-detected NMR experiments for automatic resonance assignment of IDPs and multiple-fixing SMFT processing

    Intrinsically disordered proteins (IDPs) have recently attracted much interest, due to their role in many biological processes, including signaling and regulation mechanisms. High-dimensional 13C 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

  6. A comparative study of the 13C(p,p')13C and 13C(p,n)13N reactions at Ep = 35 MeV

    Differential cross sections were measured at Ep = 35 MeV for the 13C(p,n) and 13C(p,p') reactions leading to the four low-lying states in the mirror nuclei 13N and 13C. In addition, the analyzing powers were measured for the 13C(p,p') reaction. The data are generally well accounted for by DWBA calculations except for the 13C(p,p')13C(3.09 MeV, 1/2+) reaction, for which the calculations can not even reproduce the qualitative features of the data. A comparison of the (p,n) and the (p,p') results suggests that the isoscalar part of the 13C(g.s., 1/2-) → 13C(3.09 MeV, 1/2+) transition is not correctly described by currently available shell-model wave functions. (author)

  7. Organic matter characterization during the anaerobic digestion of different biomasses by means of CPMAS 13C NMR spectroscopy

    The aim of this work was to characterize ingestates and their corresponding digestates obtained in two full-scale biogas production plants processing a) mixtures of organic wastes in co-digestion, and b) pig slurry in order to assess the organic matter transformation during anaerobic digestion by means of chemical analysis and 13CPMAS-NMR spectroscopy. Results proved that digestates obtained by different organic substrates exhibited significant chemical differences related to the different initial composition of substrates. We proposed the use of the aliphaticity index in order to highlight the different chemical nature of ingestates and their corresponding digestates. In order to verify whether the AD process leads to stabilized final products regardless the initial composition of biomass in view of a possible agronomical use of digestate, a comparison of CPMAS 13C NMR data of a number of ingestates and digestates available in literature was carried out. Results indicated that most of the aromatic structures present in the substrate tend to degrade during the process and that anaerobic digestion proceeds through preferential degradation of carbohydrates such as cellulose and hemicellulose and, as a consequence, concentration of more chemically recalcitrant aliphatic molecules occurs. -- Highlights: ► We studied anaerobic digestion by means of chemical analysis and 13CPMAS-NMR spectroscopy. ► Significant chemical differences in digestates were highlighted. ► We proposed the use of the aliphaticity index in order to differentiate digestates. ► Most of the aromatic structures tend to degrade. ► Carbohydrates are degraded and recalcitrant aliphatic molecules concentrate

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

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

    2013-12-01

    We will present details of newly-constructed specialized NMR designed to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies on unmixed slurries of minerals in the presence of CO2 or other gases. This static probe is capable of achieving 300 bar, 300C conditions, and it is designed to spectroscopically examine 13C signals in mixtures of solids, liquids, gases, and supercritical fluids. Ultimately, 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. We will give details of the hardware setup, and we will show a variety of static in situ NMR, as well as ex situ 'magic-angle spinning' NMR to show the analyses that are possible of minerals in pure form and in mixtures. In addition, specific NMR pulse sequences, techniques, and modeling will be described in detail. 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 conditions that affect the efficacy of carbonate formation in various targeted geological reservoirs (i.e., peroditite, or others). Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals, including metastable intermediates (such as hydromagnesite, or dypingite in the case of magnesium carbonate species, or vaterite in the case of calcium carbonate species). Such species are distinguishable from a combination of the 13C isotropic chemical shift, the static 13C lineshape, and changes in spin-lattice (T1) relaxation times. We will demonstrate that NMR can be used for quantitative

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

    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...

  10. Spectroscopic effects in {sup 1}H and {sup 13}C NMR spectra of 4,4`-di-substituted 3,3`-diquinolines sulfides; Efekty spektroskopowe w widmach {sup 1}H i {sup 13}C NMR 4,4`-dwupodstawionych sulfidow 3,3` dichinolinylowych

    Pluta, K. [Katedra i Zaklad Chemii Organicznej, Slaska Akademia Medyczna, Sosnowiec (Poland)

    1994-12-31

    The {sup 1}H and {sup 13}C NMR spectra of 4,4`-disubstituted sulfides of 3,3`-quinolines have been studied in CDCl{sub 3} solutions. The observed spectroscopic effects have been interpreted in terms of molecule structure and configuration. The factors being responsible for the value of spectroscopic effects have been discussed. 11 refs, 3 tabs.

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

    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

  12. Study of diabetes using naturally enriched 13C-glucose

    Following the work undertaken by Duchesne et al. since 1968, results from the use of a new method in the area of glucose metabolism are presented. Because of differences in their photosynthetic pathway, some vegetables, e.g., maize and sugarcane, are a little richer in 13C than most common foodstuffs. This weak, but significant, enrichment allows the use of maize glucose as a natural and nonradioactive tracer. In this procedure the variations of the 13C/12C ratio of exhaled CO2 are measured by mass spectrometry. By this method, we can follow, in man, the complete conversion of an oral glucose load into CO2 during a glucose tolerance test. At the same time, measurements of blood glucose and of respiratory quotient are made. They permit a useful comparison of the level of glucose in blood, the total amount of glucose consumed, and the fraction of exogenous glucose burned in the hours following oral administration. New information was obtained from these studies concerning glucose metabolism. The method was used in normal subjects and in obese and diabetic patients. Some of the diabetics were receiving an oral antidiabetic treatment. Significant differences were obtained in these cases, not only between them but also with the information given by the classical methods

  13. Protein 2D NMR analysis utilizing selective 2H and 13C enrichment

    E. coli thioredoxin has been prepared with specific residue types substituted with fully enriched 2H or 13C labeled amino acids. In 1H COSY and NOESY experiments cross peaks result from pairs of protons interacting via through-bond or through-space coupling respectively. A cross peak is eliminated if either nucleus is substituted with deuterium. Direct residue type assignments of cross peaks have been obtained by comparing data from protein samples with one residue type deuterated and data from a non-enriched sample. Selective deuteration is particularly useful for the interresidue connectivity assignments obtained by NOESY experiments which normally depend on residue type assignment information obtained from independent COSY data. Difficulties in 1H COSY type intraresidue connectivity assignments are the main reason that successful analyses generally have been limited to proteins less than 10 kilodaltons. The authors have collected 13C homonuclear COSY data which compared to the 1H experiment benefit from larger spin couplings as well as from the spectral simplification obtained by enrichment. Resolved cross peaks for the 13C-13C J1 couplings are readily observed with 30 mg of labeled protein. 1H-13C heteronuclear COSY experiments then provide an independent method of intraresidue proton spin connectivity assignments

  14. Very-high-field n.m.r. studies of bovine lung heparan sulphate oligosaccharides produced by nitrous acid deaminative cleavage. 13C-n.m.r. study of methylene resonances: degree and positions of C-6 sulphation.

    Sanderson, P N; Nieduszynski, I A; Huckerby, T N

    1983-01-01

    Oligosaccharides with the general structure UA-(GlcNAc-GlcUA-)m-aManOH (m = 1-5) (where UA represents uronic acid, GlcNAc N-acetylglucosamine, GlcUA glucuronic acid and aManOH anhydromannitol) were prepared from low-sulphated heparan sulphates of bovine lung origin by nitrous acid deaminative cleavage followed by reduction. Analysis of the methylene signals in the 100 MHz 13C-n.m.r. spectrum of the tetrasaccharide (m = 1) shows that, whereas the extent of C-6 O-sulphation in the GlcNAc is approx. 65%, in the aManOH [formerly a GlcNSO3 (N-sulphoglucosamine) residue in the parent heparan sulphate] it is only approx. 10%. In the higher oligosaccharides (m = 2-5) the gross extent of C-6 O-sulphation of GlcNAc residues falls systematically with increasing oligosaccharide size, whereas that in the aManOH residues remains below 10%. There is also evidence that the C-6 O-sulphation of the GlcNAc residues is confined to the GlcNAc residue adjacent to the non-reducing terminal uronic acid residue. It is therefore tentatively proposed that the GlcNAc in the sequence -GlcNSO3-UA-GlcNAc- might be a favoured substrate for the 6-O-sulphotransferase. It is concluded that in the low-sulphated heparan sulphates GlcNSO3 residues that do not occur in (GlcNSO3-UA-)n blocks tend to have a significantly smaller extent of C-6 O-sulphation than do GlcNAc residues that occur in -GlcNSO3-UA-GlcNAc-GlcUA-GlcNSO3-sequences. PMID:6224480

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

    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.

  16. Use of 13C measurements in humus dynamics studies

    The humic substances of the Ol and Ah horizons of a Spodo-Dystric Cambisol were characterized by exclusion chromatography on controlled pore glass followed by determination of the natural 13C/12C ratios by mass spectrometry. A significant correlation of the molecular weight of the humic substances and the δ13C values was observed. Fractions with higher molecular weight have less negative δ13C values. This relationship holds only for the humic and fulvic acids. In both horizons the non-humic substances and the very small humic substances (Kd > 0.80) were isotopically heavier than the humic substances of the second maximum (brown humic and fulvic acids). The low molecular weight organic substances of the Ol horizon showed a higher δ13C value than all other fractions. These results indicate that the non-humic substances are easily attacked by microorganismus and are therefore richer in 13C. (authors)

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

    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.

  18. Synthesis, X-ray crystallography, spectroscopic (FT-IR, 1H &13C NMR and UV), computational (DFT/B3LYP) and enzymes inhibitory studies of 7-hydroximinocholest-5-en-3-ol acetate

    Ahmad, Faheem; Parveen, Mehtab; Alam, Mahboob; Azaz, Shaista; Malla, Ali Mohammed; Alam, Mohammad Jane; Lee, Dong-Ung; Ahmad, Shabbir

    2016-07-01

    The present study reports the synthesis of 7-Hydroximinocholest-5-en-3-ol acetate (syn. 3β-acetoxycholest-5-en-7-one oxime; in general, steroidal oxime). The identity of steroidal molecule was confirmed by NMR, FT-IR, MS, CHN microanalysis and X-ray crystallography. DFT calculations on the titled molecule have been performed. The molecular structure and spectra interpreted by Gaussian hybrid computational analysis theory (B3LYP) are found to be in good correlation with the experimental data obtained from the various spectrophotometric techniques. The vibrational bands appearing in the FTIR are assigned with great accuracy using harmonic frequencies along with intensities and animated modes. Molecular properties like HOMO-LUMO analysis, chemical reactivity descriptors, MEP mapping, dipole moment and natural atomic charges have been presented at the same level of theory. Moreover, the Hirshfeld analysis was carried out to ascertain the secondary interactions and associated 2D fingerprint plots. The percentages of various interactions are pictorialized by fingerprint plots of Hirshfeld surface. Steroidal oxime exhibited promising inhibitory activity against acetylcholinesterase (AChE) as compared to the reference drug, tacrine. Molecular docking was performed to introduce steroidal molecules into the X-ray crystal structures of acetylcholinesterase at the active site to find out the probable binding mode. The results of molecular docking admitted that steroidal oxime may exhibit enzyme inhibitor activity.

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

    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

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

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

    2007-10-01

    Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. PMID:17729230

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

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

    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)

  3. X-ray, 1H/13C 2D and 3D NMR studies of the structures of davallene and adipedatol, two triterpenes isolated from American Adiantum capillus-veneris

    Two triterpenic compounds Davallene 1 and Adipedatol 2 were isolated from the roots of Mexican Adiantum capillus-veneris (Adiantaceae). The structures of both compounds are discussed on the basis of new 2D and 3D NMR spectroscopic and single crystal X-ray diffraction data. (author)

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

    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.

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

    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

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

    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.

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

    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)

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

    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.

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

    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

  10. Benchmarks for the 13C NMR chemical shielding tensors in peptides in the solid state

    Czernek, Jiří; Pawlak, T.; Potrzebowski, M. J.

    2012-01-01

    Roč. 527, - (2012), s. 31-35. ISSN 0009-2614 R&D Projects: GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : NMR * CST * DFT Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.145, year: 2012

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

    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

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

    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.

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

    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

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

    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

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

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

    2015-01-01

    Summary 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: 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

  16. Studies on irradiation stability of polystyrene by NMR

    ZHAO Xin; SUN Wan-Fu; XIE Cheng-Xi

    2004-01-01

    The irradiation stability of polystyrene (PS) was studied by 13C and 1H NMR spectra, Nuclear Overhauser Relaxation (NOE) and 13C NMR spin-lattice relaxation time (T1). The results indicate that 13C and 1H NMR chemical shifts, NOE and T1 were almost invariant with the increase of irradiation dose. This shows that polystyrene is particularly stable within 2.5 kGy doses and the mechanism of its stability is discussed.

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

    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.

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

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

    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.

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

    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

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

    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

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

    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 [1,3-13C]- and [2-13C]-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 [13C]-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 13C-13C 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 α-spectrin SH3 domain (62 residues), αB-crystallin (175 residues) and outer membrane protein G (OmpG, 281 residues) as examples. Using this procedure, over 90% of the Cα, Cβ, C' and N resonances in the core domain of αB-crystallin and around 73% in the flanking domains could be assigned (excluding 24 residues at the extreme termini of the protein)

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

    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)

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

    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

  5. 13C direct detected COCO-TOCSY: A tool for sequence specific assignment and structure determination in protonless NMR experiments

    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.

  6. Metabolism and transport studies of exogenous compounds thanks to 13C uniform isotopic enrichment

    The study of many exogenous compounds does not raise difficulties when they are isolated, purified and in quantities sufficient for the usual detection methods used in biology (Chromatography, NMR, Mass Spectrometry, etc). When they are found in a biological fluid (blood, urines,..), they are often in infinitesimal amount such as the effect of their biological matrices or the background noise that make their detection and their quantification very delicate. The use of internal standards uniformly enriched with carbon 13 and/or nitrogen 15 makes it possible to obtain a signal more easily recognizable and identifiable thanks to the presence of the isotopes (peaks shifted in a mass spectrum for example). This is why, complementary to the analytical and biochemical studies of zearalenone (ZEN) metabolism, we were interested in building mass spectra of molecules enriched (rates between 0 and 1) by various isotopes (13C, 15N, 18O and 2H). In parallel we studied the influence of the 13C enrichment on the reactivity of a given molecule, from a theoretical and an experimental point of view. (author)

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

    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.

  8. Molecular organization in the native state of woody tissue: Studies of tertiary structure and its development using the Raman microprobe, solid state {sup 13}C NMR, fluorescence spectroscopy and photoconductivity. Progress report, July 1, 1992--June 30, 1994

    Atalla, R.H.

    1995-05-01

    The work completed in the current program period is reported in 14 publications, some of which have appeared in print, and the rest of which are either in review, or will be by the end of September; five are attached to this report. The reports are conveniently discussed in four categories. The first is concerned with studies of cellulose and of the manner in which the hemicelluloses can influence the aggregation of the cellulose. This the focus is the polysaccharide matrix and the couplings that occur between its components. The second category includes the molecular modeling studies. These are new in our program, and cover explorations of the dominant characteristics of the polysaccharides and the precursors of lignin. The third group of publications address our realization that the polysaccharide matrix may well be the key to understanding the source of organization in native lignins. The fourth set of publications deal with direct conservations of organization in native lignin and the characteristic properties which reflect this organization.

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

    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

  10. NMR Assignment of Polymerase β labeled with 2H, 13C, and 15N in complex with substrate DNA

    Mueller, Geoffrey A.; DeRose, Eugene F.; Kirby, Thomas W.; London, Robert E.

    2007-01-01

    DNA Polymerase β is a multifunctional enzyme involved in base excision repair of nuclear DNA in vertebrate cells. It has been extensively studied as a model for mechanistic studies of the nucleotidyl transferase reaction, DNA synthesis fidelity, and protein-DNA interactions. Previous studies of 13C-methyl-methionine labeled Rat pol β revealed extensive dynamics in response to various DNA repair substrates (Bose-Basu et. al, 2004). We present here the first assignments of the full-length prote...

  11. (13)C solid-state NMR analysis of the most common pharmaceutical excipients used in solid drug formulations Part II: CP kinetics and relaxation analysis.

    Pisklak, Dariusz Maciej; Zielińska-Pisklak, Monika; Szeleszczuk, Łukasz; Wawer, Iwona

    2016-04-15

    Excipients used in the solid drug formulations differ in their NMR relaxation and (13)C cross-polarization (CP) kinetics parameters. Therefore, experimental parameters like contact time of cross-polarization and repetition time have a major impact on the registered solid state NMR spectra and in consequence on the results of the NMR analysis. In this work the CP kinetics and relaxation of the most common pharmaceutical excipients: anhydrous α-lactose, α-lactose monohydrate, mannitol, sucrose, sorbitol, sodium starch glycolate type A and B, starch of different origin, microcrystalline cellulose, hypromellose, ethylcellulose, methylcellulose, hydroxyethylcellulose, sodium alginate, magnesium stearate, sodium laurilsulfate and Kollidon(®) were analyzed. The studied excipients differ significantly in their optimum repetition time (from 5s to 1200s) and T1ρ(I) parameters (from 2ms to 73ms). The practical use of those differences in the excipients composition analysis was demonstrated on the example of commercially available tablets containing indapamide as an API. The information presented in this article will help to choose the correct acquisition parameters and also will save the time and effort needed for their optimization in the NMR analysis of the solid drug formulations. PMID:26836362

  12. Residue specific hydration of primary cell wall potato pectin identified by solid-state 13C single-pulse MAS and CP/MAS NMR spectroscopy.

    Larsen, Flemming H; Byg, Inge; Damager, Iben; Diaz, Jerome; Engelsen, Søren B; Ulvskov, Peter

    2011-05-01

    Hydration of rhamnogalacturonan-I (RG-I) derived from potato cell wall was analyzed by (13)C single-pulse (SP) magic-angle-spinning (MAS) and (13)C cross-polarization (CP) MAS nuclear magnetic resonance (NMR) and supported by (2)H SP/MAS NMR experiments. The study shows that the arabinan side chains hydrate more readily than the galactan side chains and suggests that the overall hydration properties can be controlled by modifying the ratio of these side chains. Enzymatic modification of native (NA) RG-I provided samples with reduced content of arabinan (sample DA), galactan (sample DG), or both side chains (sample DB). Results of these samples suggested that hydration properties were determined by the length and character of the side chains. NA and DA exhibited similar hydration characteristics, whereas DG and DB were difficult to hydrate because of the less hydrophilic properties of the rhamnose-galacturonic acid (Rha-GalA) backbone in RG-I. Potential food ingredient uses of RG-I by tailoring of its structure are discussed. PMID:21462966

  13. Structure and Metabolic-Flow Analysis of Molecular Complexity in a (13) C-Labeled Tree by 2D and 3D NMR.

    Komatsu, Takanori; Ohishi, Risa; Shino, Amiu; Kikuchi, Jun

    2016-05-10

    Improved signal identification for biological small molecules (BSMs) in a mixture was demonstrated by using multidimensional NMR on samples from (13) C-enriched Rhododendron japonicum (59.5 atom%) cultivated in air containing (13) C-labeled carbon dioxide for 14 weeks. The resonance assignment of 386 carbon atoms and 380 hydrogen atoms in the mixture was achieved. 42 BSMs, including eight that were unlisted in the spectral databases, were identified. Comparisons between the experimental values and the (13) C chemical shift values calculated by density functional theory supported the identifications of unlisted BSMs. Tracing the (13) C/(12) C ratio by multidimensional NMR spectra revealed faster and slower turnover ratios of BSMs involved in central metabolism and those categorized as secondary metabolites, respectively. The identification of BSMs and subsequent flow analysis provided insight into the metabolic systems of the plant. PMID:27060701

  14. Combined high-field 13C CP MAS NMR and low-field NMR relaxation measurements on post mortem porcine muscles.

    Bertram, Hanne Christine; Jakobsen, Hans Jørgen; Andersen, Henrik Jørgen

    2004-05-19

    Changes in postmortem muscle characteristics are investigated in muscles from eight pigs exposed to different combinations of preslaughter stress (exercise on treadmill) and stunning method (CO(2) vs electrical stunning). Solid-state (13)C cross-polarization (CP) magic-angle spinning (MAS) NMR experiments are carried out on a total of 16 rapidly frozen M. longissimus muscle biopsies taken in vivo the day before slaughter and at 45 min postmortem. Simultaneously, low-field NMR T(2) relaxation time measurements are carried out on samples from M. longissimus. Glycogen and lactate are estimated from the (13)C CP MAS spectra, and correlations of r = 0.89 and r = 0.70, respectively, to subsequent biochemical determinations using partial least squares regression (PLSR) are established. Moreover, PLSR reveals that, besides the 72 ppm signal (carbons in glycogen), a signal around 38 ppm, which increases concomitantly with lactate, is also significantly correlated to changes in glycogen/lactate. With the assumption that the 38 ppm signal reflects CH(2) in phosphocreatine/creatine, altered mobility of creatine as a result of dephosphorylation is indicated. Finally, PLSR on the 45 min (13)C CP MAS spectra also reveals correlation (r = 0.54) to the slowest relaxing T(2) population (50 min postmortem), known to reflect extra-myofibrillar water. Subsequently, evaluation of the loading plot in the PLSR analysis reveals that the correlation exclusively is associated to the 52 ppm resonance intensity. With the assumption that this resonance reflects methyl groups in choline/phosphatidyl choline, the intensity changes in the 52 ppm resonance imply alterations in membrane properties. Accordingly, the data indicate a relationship between membrane properties and the amount of water being expelled from muscle cells postmortem, which supports the hypothesis that disruption of membranes is implicated in the postmortem mobilization of muscle water. PMID:15137869

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

    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.

  16. 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

    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.

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

    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 1H and 13C 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 (1H and 13C) 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

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

    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.

  19. 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

    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...

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

    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)

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

    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 1H, 13C 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 1H and 13C NMR chemical shift assignments. (author)

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

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    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 diff...

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

    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

  4. 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

    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.

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

    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.

  6. Synthesis of new Co(III) hetero-ligand complexes with imidazole and 1-methylimidazole and their 1H, 13C and 59Co NMR spectra

    cis-[Co(en)2(1-MeIm)2]Cl3, fac-[do(dien)(ImH3]X3 (X = Cl-, NO3-, CLO4-) and fac[Co9dien)(1-MeIm)3]Cl3 complexes were prepared and characterized by absorption, 1H, NMR, 13C NMR and 59Co NMR spectra, where en, dien, ImH and 1-MeIm denote ethylenediamine, diethylenetriamine, imidazole and 1-methylimidazole, respectively. Calculated coordination-induced shifts (δcomplexed - δfree) ranged from =0.62 to -0.03 ppm for 1H and =7.11 to -1.19 ppm for 13C nuclei of imidazole ligands. The influence of imidazole methylation on 59Co NMR spectra was considered. (author)

  7. 13C- and 1H-ENDOR studies of a phenoxyl type radical

    13C- and 1H-ENDOR studies on a phenoxyl type radical in fluid solution are reported. The 13C-ENDOR resonance lines are comparable with those of the protons concerning amplitude, linewidth, and optimum experimental conditions. These findings are in contrast to previous ENDOR experiments on other 13C-labelled systems and can be explained by assuming similar hfs anisotropies for carbon-13 and protons in this radical. From saturation measurements the relaxation parameters were determined. The hyperfines couplings are discussed in terms of McLachlan and INDO calculations. For the first time natural abundance 13C-ENDOR measurement have been successful. (orig.) 891 WBU

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

    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, ...

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

    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

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

    Cozar, O. [Academy of Romanian Scientists, Splaiul Independentei 54, 050094, Bucharest, Romania and National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucureşti - Cluj-Napoca Branch (Romania); Filip, C.; Tripon, C. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Cioica, N.; Coţa, C.; Nagy, E. M. [National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucureşti - Cluj-Napoca Branch, RO-400458 Cluj-Napoca (Romania)

    2013-11-13

    The plasticizing - antiplasticizing effect of water and glycerol contents on native corn starch samples is investigated by FT-Raman and {sup 13}C 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.

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

    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

  12. Dynamics of ethylene-propylene random copolymers by (1)H and (13)C solid-state NMR.

    Mollica, G; Forte, C; Malvaldi, M; Geppi, M

    2011-03-10

    The dynamic behavior of three completely amorphous ethylene-propylene random copolymers with slightly different structural properties was investigated by means of a multifrequency global fitting approach, presented in a previous paper. To this end, the trends of NMR (1)H and (13)C spin-lattice relaxation times with temperature, obtained at different frequencies, were analyzed by means of unified motional models for the segmental main-chain motion and rotation of methyl groups about their ternary symmetry axis. To evaluate the reliability of both the models and the method used with respect to the dimensionality of the data set, as well as to identify the minimal data set to be used for getting reliable dynamic information on similar systems, the fitting results obtained from the analysis of three different experimental data sets collected on the same polymer were compared. The data collected on the three polymers using the minimal data set were analyzed and the results discussed to evaluate the degree of sensitivity of the method to differences in the dynamic behavior of structurally similar systems. The results demonstrated that the method shows good sensitivity to the use of different dynamic models depending on the number and/or type of relaxation curves included in the analysis and that variations in the dynamic features of the same motions on different systems can be revealed even in the presence of polymeric systems characterized by very similar structural properties. PMID:21319756

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

    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−

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

    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 −}.

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

    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. 1H, 13C and 13N chemical shifts and 1H-15N and 13C-15N heteronuclear spin-spin coupling constants n the NMR spectra of 5-substituted furfural oximes

    The 1H, 13C, and 15N NMR spectra of 15N-enriched 5-substituted furfural oximes were investigated. It was shown that the chemical shifts of the ring atoms and the oxime group correlate satisfactorily with the F and R substituent constants, whereas their sensitivity to the effect of the substituents is lower than in monosubstituted furan derivatives. The constants of spin-spin coupling between the ring protons and the oxime group were determined. An analysis of the 1H-1H spin-spin coupling constants (SSCC) on the basis of their stereospecificity indicates that the E isomers have primarily an s-trans conformation in polar dimethyl sulfoxide, whereas the Z isomers, on the other hand, have an s-cis conformation. The signs of the direct and geminal 13C-15N SSCC were determined for 5-trimethylsilylfurfural oxime

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

    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.

  18. 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)

    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

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

    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...

  20. Using Empirical Rules from 13C NMR Analysis to Determine the Stereochemistry of the Epoxide Located at the 5,6-position of Decalinic Systems

    Raquel M. Cravero

    2000-03-01

    Full Text Available An empiric rule derived from the analysis of the 13C NMR spectral data, allowed us to determine 5,6-epoxide stereochemistry on decalinic systems and a discussion of the scope and limitations of this rule and its extension to other carbon squeletons, is presented.

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

    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

  2. Using Empirical Rules from 13C NMR Analysis to Determine the Stereochemistry of the Epoxide Located at the 5,6-position of Decalinic Systems

    Raquel M. Cravero; Labadie, Guillermo R.; Manuel Gonzalez Sierra

    2000-01-01

    An empiric rule derived from the analysis of the 13C NMR spectral data, allowed us to determine 5,6-epoxide stereochemistry on decalinic systems and a discussion of the scope and limitations of this rule and its extension to other carbon squeletons, is presented.

  3. 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

    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.

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

    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.

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

    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.

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

    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)

  7. Solution behavior and complete 1H and 13C NMR assignments of the coenzyme B12 derivative (5'-deoxyadenosyl)cobinamide using modern 2D NMR experiments, including 600-MHz 1H NMR data

    Two-dimensional (2D) NMR methods have been used to assign completely the 1H and 13C NMR spectra of the (5'-deoxyadenosyl)cobinamide cation (AdoCbi+) in D2O. Most of the 1H spectral assignments were made by using 2D homonuclear shift correlation spectroscopy (COSY), homonuclear Hartmann-Hahn spectroscopy (HOHAHA), absorption-mode (phase sensitive) 2D nuclear Overhauser effect (NOE) spectroscopy, and spin-locked NOE spectroscopy (also called ROESY, for rotating-frame Overhauser enhancement spectroscopy). Most of the protonated carbon resonances were assigned by using 1H-detected heteronuclear multiple-quantum coherence (HMQC) spectroscopy. The nonprotonated carbon resonances, as well as the remaining unassigned 1H and 13C NMR signals, were assigned from long-range 1H-13C connectivities determined from 1H-detected multiple-bond heteronuclear multiple-quantum coherence spectroscopy (HMBC). Comparison of the 13C chemical shifts and 1H NOEs of AdoCbi+ with those of coenzyme B12 ((5'-deoxyadenosyl)cobalamin) and its benzimidazole-protonated, base-off form indicates that the electronic properties and structure of AdoCbi+ are similar to that of coenzyme B12 in the protonated, base-off form. The 13C chemical shifts of most of the carbons of AdoCbi+ do not vary significantly from those of base-off, benzimidazole-protonated coenzyme B12, indicating that the electronic environment of the corrin ring is also similar in both compounds. However, significant differences in the chemical shifts of some of the corresponding carbons of the b, d, e, and f corrin side chains in AdoCbi+ and in base-off, benzimidazole-protonated coenzyme B12 indicate that the positions of these side chains may be different in AdoCbi+ compared to base-off coenzyme B12

  8. Assignment of the side-chain 1H and 13C resonances of interleukin-1β using double- and triple-resonance heteronuclear three-dimensional NMR spectroscopy

    The assignment of the aliphatic 1H and 13C resonances of IL-1β, a protein of 153 residues and molecular mass 17.4 kDa, is presented by use of a number of novel three-dimensional (3D) heteronuclear NMR experiments which rely on large heteronuclear one-bond J couplings to transfer magnetization and establish through-bond connectivities. These 3D NMR experiments circumvent problems traditionally associated with the application of conventional 2D 1H-1H correlation experiments to proteins of this size, in particular the extensive chemical shift overlap which precludes the interpretation of the spectra and the reduced sensitivity arising from 1H line widths that are often significantly larger than the 1H-1H J couplings. The assignment proceeds in two stages. In the first step the 13Cα chemical shifts are correlated with the NH and 15N chemical shifts by a 3D triple-resonance NH-15N-13Cα (HNCA) correlation experiment which reveals both intraresidue NH(i)-15N(i)-13Cα(i) and some weaker interresidue NH(i)-15N(i)-Cα(i-1) correlations, the former via intraresidue one-bond 1JNCα and the latter via interresidue two-bond 2HNCα couplings. The second step involves the identification of side-chain spin systems by 3D 1H-13C-13C-1H correlated (HCCH-COSY) and 3D 1H-13C-13C-1H total correlated (HCCH-TOCSY) spectroscopy, the latter making use of isotropic mixing of 13C magnetization to obtain relayed connectivities along the side chains. The authors were able to obtain complete 1H and 13C side-chain assignments for all residues, with the exception of 4 (out of a total of 15) lysine residues for which partial assignments were obtained

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

    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...

  10. NMR studies of isotopically labeled RNA

    Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

    1994-12-01

    In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

  11. Effect of organic matter application on CP-MAS-13C-NMR spectra of humic acids from a brown soil

    Dou, S.

    2009-04-01

    The humified SOM or humic substances (HS) composed of humic acid (HA), fulvic acid (FA) and humin (HM) represent the most microbially recalcitrant and stable reservoir of organic carbon in soil (Piccolo et al., 2004). OM applications can influence the amount and structural characteristics of HS(Dou et al., 2008). During the past few decades, there has been much research on HS, but their chemical structure is still not fully understood (Dong, 2006).CP-MAS-13C-NMR spectroscopy was considered as an effective method to study structures of HS without dissolving problem compared with liquid 13C-NMR (Conte et al., 1997; Dou et al., 2008). It can directly measure the carbon framework and reflect the nature of HS transformation after OM application (Spaccini et al., 2000). For that reason, this method was applied in this study. The objective of this paper was to clarify the effect of long term OM application on the changes of structural characteristics in HAs, which provided new information for improving soil fertility by OM application. The experiment was carried out on a brown soil (Paleudalf in USDA Soil Taxonomy) at Shenyang Agricultural University, Liaoning province, China (N41°48'-E123°25'). The experiment included 3 treatments: zero-treatment (CKbr), and two pig manure (PM) treatments (O1 and O2) at the rates of 0.9 t ha-1 and 1.8 t ha-1 of organic carbon, respectively. The samples of the HA fraction were extracted, separated and purified according to the method described by Dou et al. (1991). Elemental composition, Differential thermal analysis (DTA), -lgK value, FT-IR and CP-MAS- 13C-NMR of HAs were performed. Effects on the contents of orgaic carbon and its composition. The contents of TOC were from 8.77 g kg-1 to 12.25 g kg-1. The relative contents in TOC for WSS, HA, and FA were 6.87%, 14.2% and 19.8%. Comparing the CKbr, the contents of WSS, HA and FA for O1 and O2 increased, but relative contents of WSS and FA decreased. The content of the HA increased after

  12. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    A novel methodology for stereospecific NMR assignments of methyl (CH3) groups of Val and Leu residues in fractionally 13C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally 13C-labeling the rest. A 2D [13C-1H] 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 CH3 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)

  13. Paramagnetic NMR relaxation in polymeric matrixes: sensitivity enhancement and selective suppression of embedded species (1H and 13C PSR filter).

    Fernandez-Megia, Eduardo; Correa, Juan; Novoa-Carballal, Ramon; Riguera, Ricardo

    2007-12-12

    A study of the practical applications of the addition of paramagnetic spin relaxation (PSR) ions to a variety of polymers (PLL, PAA, PGA, PVP, and polysaccharides such as hyaluronic acid, chitosan, mannan, and dextran) in solution (D2O and DMSO-d6) is described. Use of Gd(III), Cu(II), and Mn(II) allows a reduction of up to 500% in the 1H longitudinal relaxation times (T1), and so in the time necessary for recording quantitative NMR spectra (sensitivity enhancement) neither an increase of the spectral line width nor chemical shift changes resulted from addition of any of the PSR agents tested. Selective suppression of the 1H and 13C NMR signals of certain components (low MW molecules and polymers) in the spectrum of a mixture was attained thanks to their different sensitivity [transverse relaxation times (T2)] to Gd(III) (PSR filter). Illustration of this strategy with block copolymers (PGA-g-PEG) and mixtures of polymers and low MW molecules (i.e., lactose-hyaluronic acid, dextran-PAA, PVP-glutamic acid) in 1D and 2D NMR experiments (COSY and HMQC) is presented. In those mixtures where PSR and CPMG filters alone failed in the suppression of certain components (i.e., PVP-mannan-hyaluronic acid) due to their similarity of 1H T2 values and sensitivities to Gd(III), use of the PSR filter in combination with CPMG sequences (PSR-CPMG filter) successfully resulted in the sequential suppression of the components (hyaluronic acid first and then mannan). PMID:18004845

  14. 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.

    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

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

    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

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

    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)

  17. Ease of delignification assesment of wood from different Eucalyptus species by pyrolysis (TMAH)-GC/MS and CP/MAS 13C-NMR spectrometry

    González-Vila, Francisco Javier; Almendros Martín, Gonzalo; Río Andrade, José Carlos del; Martín Martínez, Francisco; Gutiérrez Suárez, Ana; Romero Sánchez, Juan

    1999-01-01

    Flash-pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) of woods from different species of Eucalyptus yields series of guaiacyl-type (G) and syringyl-type (S) units in slightly but characteristically different relative proportions. Such differences have been used to suggest a fine and appropriate index of the ease of delignification of the different Eucalyptus species when pulped by the Kraft process. The pyrolytic data were in agreement with those obtained from CP/MAS 13C-NMR...

  18. 13C-NMR assessment of the Pattern of organic matter transformation during domestic wastewater treatment by autothermal aerobic digestion (ATAD)

    Tony Pembroke, J.; John Barlett; Anna V. Piterina

    2009-01-01

    Abstract: The pattern of biodegradation and the chemical changes occurring in the macromolecular fraction of domestic sludge during autothermal thermophilic aerobic digestion (ATAD) was monitored and characterised via solid-state 13C-NMR CP-MAS. Major indexes such as aromaticity, hydrophobicity and alkyl/O-alkyl ratios calculated for the ATAD processed biosolids were compared by means of these values to corresponding indexes reported for sludges of different origin such as manures, soil organ...

  19. /sup 13/C nuclear magnetic resonance study of the CO/sub 2/ activation of ribulosebisphosphate carboxylase from Rhodospirillum rubrum

    O' Leary, M.H. (Univ. of Wisconsin, Madison); Joworski, R.J.; Hartman, F.C.

    1979-02-01

    Ribulosebisphosphate carboxylase (3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39) from Rhodospirillum rubrum is activated by CO/sub 2/ and Mg/sup 2 +/. /sup 13/C NMR spectra were determined for the unactivated enzyme and for enzyme that had been activated by /sup 13/CO/sub 2/ and Mg/sup 2 +/. In addition to the expected resonance for H/sup 13/CO/sub 3//sup -//CO/sub 3//sup 2 -/ at 161.8 ppM downfield from tetramethylsilane, the spectrum of the activated enzyme shows a broad resonance at 164.9 ppM. Analogy with previous NMR studies of /sup 13/CO/sub 2/ binding to hemoglobin suggests that the CO/sub 2/ activation of ribulosebisphosphate carboxylase involves formation of a carbamate between an enzyme amino group and CO/sub 2/.

  20. NMR studies of metabolism

    In this paper, the authors present applications of NMR to the study of different aspects of metabolism. The authors begin with a brief outline of localization methods that are commonly used to obtain in vivo NMR spectra. The authors then describe in more detail metabolic information recently obtained by NMR of perfused organs, intact animals, and humans. Previous reviews have already covered the applications of NMR to the study of metabolism in microorganisms, isolated or cultivated cells, and tumors. NMR spectroscopy of the brain, and human in vivo NMR spectroscopy have also been reviewed

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

    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

  2. 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

    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.

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

    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

  4. Nature of organic carbon and nitrogen in physically protected organic matter of some Australian soils as revealed by solid-state 13 C and 15 N NMR spectroscopy

    The 13C and 15N nuclear magnetic resonance (NMR) spectroscopy was applied for characterising the chemical nature of the remaining organic fraction. The 13C NMR spectroscopic comparison of the residues after UV photo-oxidation and the untreated bulk soils revealed a considerable increase in condensed aromatic structures in the residues for 4 of the 5 soils. This behaviour was recently shown to be typical for char-containing soils. In the sample where no char was detectable by NMR spectroscopy, the physically protected carbon consisted of functional groups similar to those observed for the organic matter of the bulk sample, although their relative proportions were altered. The solid-state 15N NMR spectrum from this sample revealed that some peptide structures were able to resist UV photo-oxidation, probably physically protected within the core of micro aggregates. Heterocyclic aromatic nitrogen was not detected in this spectrum, but pyrrolic nitrogen was found to comprise a major fraction of the residues after photo-oxidation of the <53 μm containing soils. Acid hydrolysis of these samples confirmed that some peptide-like material was still present. The identification of a considerable amount of aromatic carbon and nitrogen, assignable to charred material in 4 of the 5 investigated soils, supports previous observations that char largely comprises the inert or passive organic matter pool of many Australian soils. The influence of such material on the carbon and nitrogen dynamics in such soils, however, requires further research. Copyright (2000) CSIRO Australia

  5. Extraction of multiple pure component 1H and 13C NMR spectra from two mixtures: Novel solution obtained by sparse component analysis-based blind decomposition

    Sparse component analysis (SCA) is demonstrated for blind extraction of three pure component spectra from only two measured mixed spectra in 13C and 1H nuclear magnetic resonance (NMR) spectroscopy. This appears to be the first time to report such results and that is the first novelty of the paper. Presented concept is general and directly applicable to experimental scenarios that possibly would require use of more than two mixtures. However, it is important to emphasize that number of required mixtures is always less than number of components present in these mixtures. The second novelty is formulation of blind NMR spectra decomposition exploiting sparseness of the pure components in the wavelet basis defined by either Morlet or Mexican hat wavelet. This enabled accurate estimation of the concentration matrix and number of pure components by means of data clustering algorithm and pure components spectra by means of linear programming with constraints from both 1H and 13C NMR experimental data. The third novelty is capability of proposed method to estimate number of pure components in demanding underdetermined blind source separation (uBSS) scenario. This is in contrast to majority of the BSS algorithms that assume this information to be known in advance. Presented results are important for the NMR spectroscopy-associated data analysis in pharmaceutical industry, medicine diagnostics and natural products research.

  6. Stability and biodegradability of humic substances from Arctic soils of Western Siberia: insights from 13C-NMR spectroscopy and elemental analysis

    Ejarque, E.; Abakumov, E.

    2015-11-01

    Arctic soils contain large amounts of organic matter which, globally, exceed the amount of carbon stored in vegetation biomass and in the atmosphere. Recent studies emphasize the potential sensitivity for this soil organic matter (SOM) to be mineralised when faced with increasing ambient temperatures. In order to better refine the predictions about the response of SOM to climate warming, there is a need to increase the spatial coverage of empirical data on SOM quantity and quality in the Arctic area. This study provides, for the first time, a characterisation of SOM from the Gydan Peninsula in the Yamal Region, Western Siberia, Russia. On the one hand, soil humic acids and their humification state were characterised by measuring the elemental composition and diversity of functional groups using solid-state 13C-NMR spectroscopy. Also, the total mineralisable carbon was measured. Our results show that there is a uniformity of SOM characteristics throughout the studied region, as well as within soil profiles. Such in-depth homogeneity, together with a predominance of aliphatic carbon structures, suggests the accumulation in soil of raw and slightly decomposed organic matter. Moreover, results on total mineralisable carbon suggest a high lability of these compounds. The mineralisation rate was found to be independent of SOM quality, and to be mainly explained solely by the total carbon content. Overall, our results provide further evidence on the fundamental role that the soils of Western Siberia may have on regulating the global carbon balance when faced with increasing ambient temperatures.

  7. Applications of the 18O-isotope shift on 13C and 15N nuclear magnetic resonance spectroscopy to the study of bioorganic reaction mechanisms

    The study of reactions involving the formation and cleavage of carbon-oxygen or nitrogen-oxygen bonds has been significantly aided by recent demonstrations of the generality and characteristics of the 18O-isotope shift in 13C and 15N nuclear magnetic resonance spectroscopy. In many instances, the magnitudes of the 18O-induced isotopic shifts are sufficiently large as to permit the use of even modest NMR instrumentation and natural abundance 13C. Studies involving less soluble compounds, higher molecular weight materials or relatively rapid reactions may often be carried out using 13C enrichment. Because NMR spectroscopy is non-destructive, it has proven to be extremely useful in the study of natural product biosynthetic pathways. Another area where important applications are being made is in the study of enzymatic and non-enzymatic reaction mechanisms. The characteristics of the 18O isotope shift in 13C NMR spectroscopy are reviewed. Several examples from the work of other groups in the area of natural product biosynthesis are briefly mentioned. This is followed by a number of illustrative applications in the area of bioorganic and enzymatic reaction mechanism that have been examined in our laboratory. The enzymatic examples include acid phosphatases, epoxide hydratase, acetylcholinesterase and asparaginase. 20 refs.; 1 figure

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

    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.

  9. 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

    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.

  10. The conformational stability, solvation and the assignments of the experimental infrared, Raman, 1H and 13C NMR spectra of the local anesthetic drug lidocaine

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

    2015-05-01

    The structure, vibrational and 1H and 13C NMR spectra of the local anesthetic drug lidocaine were investigated by the B3LYP/6-311G∗∗ calculations. The molecule was predicted to have the non-planar cis (NCCN ∼ 0°) structures being about 2-6 kcal/mol lower in energy than the corresponding trans (NCCN ∼ 180°) forms. The calculated NCCN (9.6°) and CNCC (-132.2°) torsional angles were in a good qualitative agreement with the reported X-ray angles (3.1 and 13.0°, -102.67 and -77.9°, respectively, for H-bonded dimers). The Gibbs energy of solution of lidocaine in formamide, water, dimethylsulfoxide, acetonitrile, methanol, ethanol and chloroform solutions was estimated at the B3LYP level. The predicted affinity of lidocaine toward the alcohols, acetonitrile and chloroform solutions was in excellent agreement with the reported experimental solubility of the drug in organic solvents. The analysis of the observed vibrational spectra is consistent with the presence of lidocaine in only one conformation at room temperature. The 1H and 13C NMR spectra of lidocaine were interpreted by experimental and DFT calculated chemical shifts of the drug. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine is 0.47 and 8.26 ppm, respectively.

  11. Synthesis of ring-13C-labelled and ring-demethylated retinals

    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

  12. 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

    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.

  13. Insight into dissolution mechanism of cellulose in [C4mim][CH3COO]/DMSO solvent by 13C NMR spectra

    Xu, Airong; Zhang, Yibo

    2015-05-01

    Recently, it has been reported that 1-butyl-3-methylimidazolium acetate/dimethyl sulfoxide ([C4mim][CH3COO]/DMSO) can efficiently dissolve cellulose at room temperature. In the present study, 13C NMR measurements of 1-butyl-3-methylimidazolium acetate [C4mim][CH3COO] and cellulose were carried out in [C4mim][CH3COO]/DMSO-d6 (Deuterated dimethyl sulfoxide)/cellulose solution to directly reveal the possible dissolution mechanism of cellulose in true [C4mim][CH3COO]/DMSO solvent. The results indicate that both cation and anion of [C4mim][CH3COO] in [C4mim][CH3COO]/DMSO solvent dominate cellulose dissolution, and DMSO mainly serves to dissociate the ion pairs in [C4mim][CH3COO] into solvated cations and anions. Moreover, the hydrogen bonding interaction of anion of [C4mim][CH3COO] with cellulose hydroxyl proton is much stronger than that of cation of [C4mim][CH3COO] with cellulose hydroxyl oxygen.

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

    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.

  15. Distinguishing tautomerism in the crystal structure of (Z)-N-(5-ethyl-2,3-dihydro-1,3,4-thiadiazol-2-ylidene)-4-methylbenzenesulfonamide using DFT-D calculations and (13)C solid-state NMR

    Li, Xiaozhou; Bond, Andrew D; Johansson, Kristoffer E;

    2014-01-01

    The crystal structure of the title compound, C11H13N3O2S2, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated (13)C solid-state NMR spectra [Hangan et al. (2010). Acta Cryst. B66, 615....... Calculation of the (13)C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured (13)C SS-NMR spectrum....

  16. Magnetic resonance butterfly coils: Design and application for hyperpolarized 13C studies

    Giovannetti, Giulio; Frijia, Francesca; Attanasio, Simona;

    2013-01-01

    Hyperpolarized 13C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design...... coil throughout the volume of interest for cardiac imaging in pig. Experimental SNR-vs-depth profiles, extracted from the [1-13C]acetate phantom chemical shift image (CSI), permitted to highlight the performance of the proposed coils configuration. © 2013 Elsevier Ltd. All rights reserved....

  17. Short, synthetic and selectively 13C-labeled RNA sequences for the NMR structure determination of protein–RNA complexes

    Wenter, Philipp; Reymond, Luc; Auweter, Sigrid D.; Allain, Frédéric H.-T.; Pitsch, Stefan

    2006-01-01

    We report an optimized synthesis of all canonical 2′-O-TOM protected ribonucleoside phosphoramidites and solid supports containing [13C5]-labeled ribose moieties, their sequence-specific introduction into very short RNA sequences and their use for the structure determination of two protein–RNA complexes. These specifically labeled sequences facilitate RNA resonance assignments and are essential to assign a high number of sugar–sugar and intermolecular NOEs, which ultimately improve the precis...

  18. Solid state structure by X-ray and 13C CP/MAS NMR of new 5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarins

    Ostrowska, Kinga; Maciejewska, Dorota; Dobrzycki, Łukasz; Socha, Pawel

    2016-05-01

    5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarin (1) and 6-acetyl-5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarin (2), structurally related, were synthesized using both conventional and microwave-assisted approach. An impact of acetyl groups on the molecular structure of coumarin derivatives has been examined. Crystals of 2 were investigated using single crystal and powder X-ray diffraction techniques. Compound 2 crystallizes forming two polymorphs (denoted as 2_1 and 2_2), both belonging to P21/c space group. Both polymorphs are comparably stable and can be formed simultaneously during crystallization process. The solid state structure was also analysed using the fully resolved 13C CP/MAS NMR. The double signals with the intensity ratio of about 1:1 which were observed in the 13C CP/MAS NMR spectrum of compound 1 must arise due to the presence of two conformers of 1. In contrast, NMR spectrum recorded for powder mixture of two polymorphs of compound 2 displays no signal splitting. This is related to structural similarities of molecules in both polymorphs.

  19. Backbone dynamics of a model membrane protein: assignment of the carbonyl carbon 13C NMR resonances in detergent-solubilized M13 coat protein

    The major coat protein of the filamentous bacteriophage M13 is a 50-residue amphiphilic polypeptide which is inserted, as an integral membrane-spanning protein, in the inner membrane of the Escherichia coli host during infection. 13C was incorporated biosynthetically into a total of 23 of the peptide carbonyls using labeled amino acids (alanine, glycine, lysine, phenylalanine, and proline). The structure and dynamics of carbonyl-labeled M13 coat protein were monitored by 13C nuclear magnetic resonance (NMR) spectroscopy. Assignment of many resonances was achieved by using protease digestion, pH titration, or labeling of the peptide bond with both 13C and 15N. The carbonyl region of the natural-abundance 13C NMR spectrum of M13 coat protein in sodium dodecyl sulfate solution shows approximately eight backbone carbonyl resonances with line widths much narrower than the rest. Three of these more mobile residues correspond to assigned peaks (glycine-3, lysine-48, and alanine-49) in the individual amino acid spectra, and another almost certainly arises from glutamic acid-2. A ninth residue, alanine-1, also gives rise to a very narrow carbonyl resonance if the pH is well above or below the pK/sub a/ of the terminal amino group. These data suggest that only about four residues at either end of the protein experience large-amplitude spatial fluctuations; the rest of the molecule is essentially rigid on the time scale of the overall rotational tumbling of the protein-detergent complex. The relative exposure of different regions of detergent-bound protein was monitored by limited digestion with proteinase K. Comparable spectra and digestion patterns were obtained when the protein was solubilized in sodium deoxycholate, suggesting that the coat protein binds both amphiphiles in a similar fashion

  20. Enhancing the [13C]bicarbonate signal in cardiac hyperpolarized [1‐13C]pyruvate MRS studies by infusion of glucose, insulin and potassium

    Lauritzen, Mette Hauge; Laustsen, Christoffer; Butt, Sadia Asghar;

    2013-01-01

    A change in myocardial metabolism is a known effect of several diseases. MRS with hyperpolarized 13C‐labelled pyruvate is a technique capable of detecting changes in myocardial pyruvate metabolism, and has proven to be useful for the evaluation of myocardial ischaemia in vivo. However, during...... fasting, the myocardial glucose oxidation is low and the fatty acid oxidation (β‐oxidation) is high, which complicates the interpretation of pyruvate metabolism with the technique. The aim of this study was to investigate whether the infusion of glucose, insulin and potassium (GIK) could increase the...... myocardial glucose oxidation in the citric acid cycle, reflected as an increase in the [13C]bicarbonate signal in cardiac hyperpolarized [1‐13C]pyruvate MRS measurements in fasted rats. Two groups of rats were infused with two different doses of GIK and investigated by MRS after injection of hyperpolarized...

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

    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

  2. {sup 1}H and {sup 13}C NMR spectroscopy of 5-methyl-5H-indole-[2,3-b]quinoline; Spektroskopia {sup 1}H i {sup 13}C NMR 5-metylo-5H-indole-[2,3-b]chinoliny

    Kamienska-Trela, K.; Kania, L.; Kaczmarek, L. [Inst. Chemii Organicznej, Polska Akademia Nauk, Warsaw (Poland)

    1994-12-31

    {sup 1}H and {sup 13}C NMR spectra of 5-methyl-5H-indole quinoline have been measured in CDCl{sub 3} solution. The full assignation of resonant signals observed for this compound has been done. Also the chemical shifts {delta}({sup 1}H) and {delta}({sup 13}C) have been determined. That parameters as being tightly dependent on electronic density in molecule are very important also from the view point of biological activity of investigated compound. 3 refs, 1 fig., 1 tab.

  3. 1H and 13C NMR Chemical Shift Assignments and Conformational Analysis for the Two Diastereomers of the Vitamin K Epoxide Reductase Inhibitor Brodifacoum

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

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

    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...

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

    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.

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

    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)

  7. Cationic Closo-carboranes 2. Do computed 11B and 13C NMR chemical shifts support their experimental availability?

    Hnyk, Drahomír; Jayasree, E.G.

    2013-01-01

    Roč. 34, č. 8 (2013), s. 656-661. ISSN 0192-8651 R&D Projects: GA ČR GAP208/10/2269 Institutional support: RVO:61388980 Keywords : boron clusters * weakly-coordinating cations * 11B NMR * dynamic electron correlation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.601, year: 2013

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

    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.

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

    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...

  10. Stability and biodegradability of organic matter from Arctic soils of Western Siberia: insights from 13C-NMR spectroscopy and elemental analysis

    Ejarque, E.; Abakumov, E.

    2016-01-01

    Arctic soils contain large amounts of organic matter which, globally, exceed the amount of carbon stored in vegetation biomass and in the atmosphere. Recent studies emphasise the potential sensitivity for this soil organic matter (SOM) to be mineralised when faced with increasing ambient temperatures. In order to better refine the predictions about the response of SOM to climate warming, there is a need to increase the spatial coverage of empirical data on SOM quantity and quality in the Arctic area. This study provides, for the first time, a characterisation of SOM from the Gydan Peninsula in the Yamal Region, Western Siberia, Russia. On the one hand, soil humic acids and their humification state were characterised by measuring the elemental composition and diversity of functional groups using solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy. Also, the total mineralisable carbon was measured. Our results indicate that there is a predominance of aliphatic carbon structures, with a minimal variation of their functional-group composition both regionally and within soil depth. This vertical homogeneity and low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Mineralisation rates were found to be independent of SOM quality, and to be mainly explained solely by the total carbon content. Overall, our results provide further evidence on the sensitivity that the soils of Western Siberia may have to increasing ambient temperatures and highlight the important role that this region can play in the global carbon balance under the effects of climate warming.

  11. 1 H and 13 C NMR of dipyridamole derivatives in homogeneous solution: correlation to the electron density

    Dipyridamole, 2,6-bis(diethanolamino)-4,8-dipiperidino-pyrimido-pyrimidine, (DIP) has been widely used as a drug. The biological activity of this drug depends largely upon the nature of the substituents. In the present work, data on hydrogen-1 and carbon-13 NMR of DIP and some of its derivates are analysed in order to improve the knowledge of physico-chemical properties of these compounds. The methodology is presented. Results are reported and discussed

  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

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

    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%.

  14. Experimental study of the 13C+12C fusion reaction at deep sub-barrier energies

    Tudor, D.; Chilug, A. I.; Straticiuc, M.; Trache, L.; Chesneanu, D.; Toma, S.; Ghita, D. G.; Burducea, I.; Margineanu, R.; Pantelica, A.; Gomoiu, C.; Zhang, N. T.; Tang, X.; Li, Y. J.

    2016-04-01

    Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied because of their significance for a wide variety of stellar burning scenarios. One important stellar reaction is 12C+12C, but it is difficult to measure it in the Gamow window because of very low cross sections and several resonances occurring. Hints can be obtained from the study of 13C+12C reaction. We have measured this process by an activation method for energies down to Ecm=2.5 MeV using 13C beams from the Bucharest 3 MV tandetron and gamma-ray deactivation measurements in our low and ultralow background laboratories, the latter located in a salt mine about 100 km north of Bucharest. Results obtained so far are shown and discussed in connection with the possibility to go even further down in energy and with the interpretation of the reaction mechanism at such deep sub-barrier energies.

  15. Structure of Λ13C hypernucleus studied by the (K-, π-γ) reaction

    The BNL-AGS/E929 experiment was carried out to study energy levels of the Λ13C hypernucleus by a gamma-ray spectroscopy. Energy splitting of the spin-orbit doublets, ((1)/(2))- and ((3)/(2))- states, was estimated precisely. The excitation energy of the 1st ((3)/(2))+ state was also measured. We discuss the symmetric and the anti-symmetric spin-orbit interactions between a Λ particle and a nucleon from the measurement

  16. Flavonoids from Lonchocarpus araripensis (Leguminoseae): isolation, unequivocal assignment of NMR signals 1H and 13C and conformational analysis

    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-[6,7,2,3]-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)

  17. Molecular structure and vibrational bands and 13C chemical shift assignments of both enmein-type diterpenoids by DFT study

    Wang, Tao; Wu, Yi fang; Wang, Xue liang

    2014-01-01

    We report here theoretical and experimental studies on the molecular structure and vibrational and NMR spectra of both natural enmein type diterpenoids molecule (6, 7-seco-ent-kaurenes enmein type), isolated from the leaves of Isodon japonica (Burm.f.) Hara var. galaucocalyx (maxin) Hara. The optimized geometry, total energy, NMR chemical shifts and vibrational wavenumbers of epinodosinol and epinodosin have been determined using B3LYP method with 6-311G (d,p) basis set. A complete vibrational assignment is provided for the observed IR spectra of studied compounds. The calculated wavenumbers and 13C c.s. are in an excellent agreement with the experimental values. Quantum chemical calculations at the B3LYP/6-311G (d,p) level of theory have been carried out on studied compounds to obtain a set of molecular electronic properties (MEP,HOMO, LUMO and gap energies ΔEg). Electrostatic potential surfaces have been mapped over the electron density isosurfaces to obtain information about the size, shape, charge density distribution and chemical reactivity of the molecules.

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

    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

  19. Isotope labeling for NMR studies of macromolecular structure and interactions

    Wright, P.E. [Scripps Research Institute, La Jolla, CA (United States)

    1994-12-01

    Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform {sup 13}C, {sup 15}N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific {sup 13}C and {sup 15}N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions.

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

    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.

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

    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.

  2. 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

    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.

  3. Non-fermi liquid behavior of the organic superconductor κ-(BEDT-TTF)4Hg2.89Br8 probed by 13C-NMR

    We assessed 13C-NMR measurements in an organic salt, κ-(BEDT-TTF)4Hg2.89Br8, which exhibits superconductivity at 4.3 K under ambient pressure. We observed that (T1T)-1 of H|| and -perpendicular layer at ambient pressure increased as the temperature was decreased to 7 K, but decreased further at lower temperatures, suggesting that the decrease of (T1T)-1 was not due to the superconductive fluctuations, but due to the magnetism of the conduction electrons. Application of pressure suppresses (T1T)-1, with (T1T)-1 becoming constant above 2 GPa. These results suggest that applying pressure alters the electron system from a non-Fermi liquid (NFL) to a Fermi liquid (FL) state and that antiferromagnetic fluctuations contribute to the origin of NFL behavior. Whereas most organic conductors show Fermi liquid behavior, this salt is an organic superconductor that shows NFL behavior due to the antiferromagnetic fluctuations.

  4. The Effect of Solvent Accessible Surface on Hammett-Type Dependencies of Infinite Dilution 29Si and 13C NMR Shifts in Ring Substituted Silylated Phenols Dissolved in Chloroform and Acetone

    Blechta, Vratislav; Šabata, Stanislav; Sýkora, Jan; Hetflejš, Jiří; Soukupová, Ludmila; Schraml, Jan

    2012-01-01

    Roč. 50, č. 2 (2012), s. 128-134. ISSN 0749-1581 R&D Projects: GA AV ČR IAA400720706; GA ČR GA203/06/0738 Institutional research plan: CEZ:AV0Z40720504 Keywords : 1H NMR * 13C NMR * 29Si NMR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.528, year: 2012

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

    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

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

    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.

  7. 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

    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.

  8. Functional studies using NMR

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

  9. Synthesis and NMR Spectral Analysis of Amine Heterocycles: The Effect of Asymmetry on the [superscript 1]H and [superscript 13]C NMR Spectra of N,O-Acetals

    Saba, Shahrokh; Ciaccio, James A.; Espinal, Jennifer; Aman, Courtney E.

    2007-01-01

    The stereochemical investigation is conducted to give students the combined experience of chemical synthesis of amines and N-heterocycles and structural stereochemical analysis using NMR spectroscopy. Students are introduced to the concept of topicity-stereochemical relationships between ligands within a molecule by synthesizing N,O-acetals.

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

    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.)

  11. The effects of anticalcification treatments and hydration on the molecular dynamics of bovine pericardium collagen as revealed by 13C solid-state NMR.

    deAzevedo, E R; Ayrosa, A M I B; Faria, G C; Cervantes, H J; Huster, D; Bonagamba, T J; Pitombo, R N M; Rabbani, S R

    2010-09-01

    This article describes a solid-state NMR (SSNMR) investigation of the influence of hydration and chemical cross-linking on the molecular dynamics of the constituents of the bovine pericardium (BP) tissues and its relation to the mechanical properties of the tissue. Samples of natural phenethylamine-diepoxide (DE)- and glutaraldehyde (GL)-fixed BP were investigated by (13)C cross-polarization SSNMR to probe the dynamics of the collagen, and the results were correlated to the mechanical properties of the tissues, probed by dynamical mechanical analysis. For samples of natural BP, the NMR results show that the higher the hydration level the more pronounced the molecular dynamics of the collagen backbone and sidechains, decreasing the tissue's elastic modulus. In contrast, in DE- and GL-treated samples, the collagen molecules are more rigid, and the hydration seems to be less effective in increasing the collagen molecular dynamics and reducing the mechanical strength of the samples. This is mostly attributed to the presence of cross-links between the collagen plates, which renders the collagen mobility less dependent on the water absorption in chemically treated samples. PMID:20641133

  12. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  13. Combined analysis of the essential oil of Chenopodium ambrosioides by GC, GC-MS and 13C-NMR spectroscopy: quantitative determination of ascaridole, a heat-sensitive compound.

    Cavalli, Jean-François; Tomi, Félix; Bernardini, Antoine-François; Casanova, Joseph

    2004-01-01

    A commercial sample of the essential oil of Chenopodium ambrosioides L. from Madagascar was analysed by GC, GC-MS and 13C-NMR. By GC analysis, the major constituents were found to be ascaridole (1) (41.8%), isoascaridole (2) (18.1%), p-cymene (16.2%), alpha-terpinene (9.7%) and limonene (3.8%). However, ascaridole undergoes a partial thermal isomerisation to 2 and hence the amount of 1 is under-estimated by GC analysis. The actual contents of 1 and 2 (55.3 and 4.6%, respectively) were obtained following combined analysis of the sample by GC and 13C-NMR. Several hydroxy- and polyhydroxy-menthanes were identified by 13C-NMR. PMID:15508830

  14. Preliminary Study of 13C/12C Application for the Detection of Adulterated Honey

    Honey and pollen in natural products derived from the same plant both share the same carbon source; as a result their 13C isotope signature should be identical. The majority of honey adulteration in Thailand was done particularly by adding cheap sugars such as high sucrose cane syrup (HSCS). The accepted differences in 13C/12C between honey and its associated protein extract is -1δ/ο deviation, which provides the international benchmark of 7% C4 sugar addition. This study reports the preliminary detection of adulterated Thai honey samples by using isotope ratio mass spectrometer coupled to elemental analyzer (EAIRMS). The 5 Thailand honey samples and the pure honey were adulterated with HSCS dilution as: 0, 0.5, 1, 5, 7, 10, 15 and 50%, respectively. The results were found that two of the Thai honey samples and of 10, 15, and 50% dilution were adulterated. The result of analyzed cane sugar of ten replicates were found -11.2 and -10.8 δdeviation, respectively.

  15. Brominated Compounds from Marine Sponges of the Genus Aplysina and a Compilation of Their 13C NMR Spectral Data

    Jose Maria Barbosa-Filho; Celidarque da Silva Dias; Luis Cezar Rodrigues; Narlize Silva Lira; Petronio Filgueiras de Athayde-Filho; Emidio V. L. da Cunha; Josean Fechine Tavares; Ricardo Carneiro Montes; Marcelo Sobral da Silva

    2011-01-01

    Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has ...

  16. 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

    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.

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

    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 13C-labeled biomolecules, inter-residue, inter-segmental, and intermolecular 13C–13C 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 1H-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 13C T1 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 T1 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 T1 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-residue and intermolecular correlation peaks, which

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

    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

  19. 13C nuclear magnetic resonance study of the complexation of calcium by taurine

    13C Nuclear magnetic resonance chemical shifts, 1J/sub c-c/ scalar coupling constants, spin-lattice relaxation times, and nuclear Overhauser effects were determined for taurine-[1, 2 13C] and a taurine-[1 13C] and taurine-[2 13C] mixture in the presence and absence of calcium. Comparison of taurine titration shifts to values for related compounds reveals some unusual electronic properties of the taurine molecule. Stability constants of 1:1 calcium complexes with taurine zwitterions and anions, as well as their 13C chemical shifts, were obtained by least squares analysis of titration curves measured in the presence of calcium. The stability constants of calcium-taurine complexes were significantly lower than previous values and led to estimates that only approximately one percent of intracellular calcium of mammalian myocardial cells would exist in a taurine complex

  20. Depletion of 13C in lignin and its implications for stable carbon isotope studies

    Stable carbon isotope compositions of organic matter are now widely used to trace carbon flow in ecosystems, and have been instrumental in shaping current perceptions of the importance of terrestrial vegetation to estuarine and coastal marine environments. A general assumption in these and other studies relying on carbon isotope compositions for source identification of organic matter has been that the major biochemical components of plant tissues are isotopically invariant. We report here large differences between the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, and demonstrate that the carbon isotope composition of Spartina detritus gradually changes during biogeochemical processing as polysaccharides are preferentially removed, leaving a material that is relatively enriched in lignin-derived carbon and depleted in 13C. (author)

  1. Study of 11B + 12C and 10B + 13C fusion cross sections

    In an effort to understand the mechanism responsible for fusion cross section limitations in light heavy-ion systems, four entrance channels which form the 23Na compound nucleus have been studied. A limitation mechanism based on a critical density of compound nucleus states does not appear to be responsible for the fusion cross section limitation at energies from approximately one to three times the Coulomb barrier energy. The possibility exists, however, that such a process becomes important at higher energies. To address this question, measurements which utilize the Argonne tandem-linac accelerator have now been completed in the energy range 42.5-80.9 MeV for the 11B + 12C and the 10B + 13C. The preliminary findings of this work are reported here

  2. Analysis of mercerization process based on the intensity change of deconvoluted resonances of 13C CP/MAS NMR: Cellulose mercerized under cooling and non-cooling conditions

    The area intensity change of C1, C4, and C6 in spectrum obtained by 13C 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

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

    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

  4. Application of 13C NMR spectroscopy and of FAB mass spectrometry in the investigation of the minor triterpenoids of Thalictrum minus

    Five minor triterpenoids have been isolated from the chloroform-soluble fraction of a methanolic extract of Thalictrum minus by chromatography on silica gel: (I) — oleanolic acid; (II) — oleanolic acid 3-0-α-L-arabinopyranoside; (III) — oleanolic acid 3-0-[0-β-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranoside]; (IV) — oleanolic acid 3-0-[0-α-L-rhamnopyranosyl(1 → 2)-0-β-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranoside]; and (V) — oleanolic acid 28-0-β-D-glucopyranoside 3-0-[0-β-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranoside]. This is the first time that any of the compounds isolated have been detected in plants of the genusThalictrum. The possibility has been shown of determining the structures of triterpene glycosides on the basis of 13C NMR spectroscopy and FAB mass spectrometry without chemical transformations of the glycosides

  5. 13C-NMR Assessment of the Pattern of Organic Matter Transformation during Domestic Wastewater Treatment by Autothermal Aerobic Digestion (ATAD

    J.Tony Pembroke

    2009-08-01

    Full Text Available Abstract: The pattern of biodegradation and the chemical changes occurring in the macromolecular fraction of domestic sludge during autothermal thermophilic aerobic digestion (ATAD was monitored and characterised via solid-state 13C-NMR CP-MAS. Major indexes such as aromaticity, hydrophobicity and alkyl/O-alkyl ratios calculated for the ATAD processed biosolids were compared by means of these values to corresponding indexes reported for sludges of different origin such as manures, soil organic matter and certain types of compost. Given that this is the first time that these techniques have been applied to ATAD sludge, the data indicates that long-chain aliphatics are easily utilized by the microbial populations as substrates for metabolic activities at all stages of aerobic digestion and serve as a key substrate for the temperature increase, which in turn results in sludge sterilization. The ATAD biosolids following treatment had a prevalence of O-alkyl domains, a low aromaticity index (10.4% and an alkyl/O-alkyl ratio of 0.48 while the hydrophobicity index of the sludge decreased from 1.12 to 0.62 during the treatment. These results have important implications for the evolution of new ATAD modalities particularly in relation to dewatering and the future use of ATAD processed biosolids as a fertilizer, particularly with respect to hydrological impacts on the soil behaviour.

  6. Spectroscopic study and astronomical detection of doubly 13C-substituted ethyl cyanide

    Margulès, L.; Belloche, A.; Müller, H. S. P.; Motiyenko, R. A.; Guillemin, J.-C.; Garrod, R. T.; Menten, K. M.

    2016-05-01

    Context. We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly 13C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly 13C-substituted isotopomers should also be detectable. Aims: We want to determine the spectroscopic parameters of all three doubly 13C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. Methods: We investigated the laboratory rotational spectra of the three species between 150 GHz and 990 GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the 12C and singly 13C-substituted isotopologues assuming local thermodynamic equilibrium. Results: We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly 13C-substituted isotopomers. The quantum numbers reach J ≈ 115 and Ka ≈ 35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The 12C/13C column density ratio of the isotopomers with one 13C atom to those with two 13C atoms is about 25. Conclusions: Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two 13C atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least ν19 = 1 at ~1130 K and up to ν13 + ν21 = 2 at ~600 K for the isotopologues with one 13C atom in

  7. Experimental study on L-[1-13C] phenylalanine breath test for quantitative assessment of liver function with animal

    Objective: Using a small animal breath test model we designed and L-[1-13C] phenylalanine breath test (13C-PheBT) of rats, the authors investigated its feasibility and validity and determined effective parameter of the test. Methods: Twenty male Sprague-Dawley (SD) weighting 280-290 g rats randomized into two groups acute hepatitis rats (n=10) and control rats (n=10). Hepatitis was induced by carbon tetrachloride (CCl4) olive oil administration through intragastric gavage. PheBT was assisted by small mechanical ventilator improved and air samples were collected discontinuously, 20 mg/kg body weight L-[1-13C] phenylalanine (13C-Phe) was administered intravenously. Twenty-nine breath samples were taken before and different intervals within sixty minutes after administration. 13Cenrichment was measured by isotope ratio mass spectrometer. Results: All time phase curves of 13C enrichment in rat breath reached a peak almost at 2 min after the intravenous administration of 13C-Phe. The PheBT parameters, 13C excretion rate constant (PheBT-K), of CCl4 hepatitis rats were significantly lower than that of normal control rats [(2.45 ± 0.25) x 10-2 min-1 vs (2.98 ± 0.19) x 10-2 min-1, t = 5.40, P13C fast phase disposition constant did not statistically differ between the two groups (t=0.58, P>0.05). PheBT-K had significant negative cor-relation with serum ALT, AKP, TBA and total bilirum TBIL (the correlation coefficient r is -0.74, -0.73, -0.82 and -0.67 respectively, P0.05). Conclusions: It was indicated that the small animal breath test model we designed was a virtual tool to use in experimental study on breath test and PheBT-K was a sensitive index. (authors)

  8. Implication of Formation Mechanisms of HC5N in TMC-1 as Studied by 13C Isotopic Fractionation

    Taniguchi, Kotomi; Saito, Masao; Sakai, Nami; Nakamura, Fumitaka; Kameno, Seiji; Takano, Shuro; Yamamoto, Satoshi

    2015-01-01

    We observed the J = 9-8 and 16-15 rotational transitions of the normal species and five 13C isotopologues of HC5N to study its formation mechanisms toward the cyanopolyyne peak in Taurus Molecular Cloud-1, with the 45-m radio telescope of Nobeyama Radio Observatory. We detected the five 13C isotopologues with high signal-to-noise ratios between 12 and 20, as well as the normal species. The abundance ratios of the five 13C isotopologues of HC5N are found to be 1.00:0.97:1.03:1.05:1.16 (0.19) for [H13CCCCCN]:[HC13CCCCN]:[HCC13CCCN]:[HCCC13CCN]:[HCCCC13CN]. We do not find any significant differences among the five 13C isotopologues. The averaged [HC5N]/[13C isotopologues] abundance ratio is determined to be 94 (6), which is slightly higher than the local interstellar elemental 12C/13C ratio of 60-70. Possible formation pathways are discussed on the basis of these results.

  9. The study of diet and trophic relationships through natural abundance 13C

    Measurement of the natural abundances of stable carbon atoms (δ13C) is a powerful way to study the dietary organization of an entire ecosystem. In some cases, it is often the only tool available for distinguishing and tracing different food sources. However, like all methods, it has certain limitations; care must always be taken in designing the experiment and in interpreting the results. This chapter covers all of these aspects of the method. Section 1 gives examples of specific areas in which the technique is valuable, a general discussion of its limitations and how to work around them, and finally some examples of particular studies that are used to illustrate the different procedures. Section 2 enumerates the various factors important for both experimental design and for interpretation of results. Section 3 describes the particular steps necessary to obtain, process, and preserve samples. General techniques and principles are given that can be applied to all ecosystems. Specific methods for marine plankton illustrate how the principles can be applied

  10. 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

    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.

  11. Synthesis of 13C-labelled lactose for metabolic studies in subjects with gastrointestinal disorders

    The long-range goals included development of a 13C-labelled lactose method for measuring lactose malabsorption in patients with diarrhea. The short-term goals included assembling a nuclear magnetic resonance system and a computer system for spectra analysis. The latter results are the subject of the report. (author)

  12. Spectroscopic study and astronomical detection of doubly 13C-substituted ethyl cyanide

    Margulès, L; Müller, H S P; Motiyenko, R A; Guillemin, J -C; Garrod, R T; Menten, K M

    2016-01-01

    We have performed a spectral line survey called EMoCA toward Sagittarius B2(N) between 84 and 114 GHz with ALMA. Line intensities of the main isotopic species of ethyl cyanide and its singly 13C-substituted isotopomers observed toward the hot molecular core Sgr B2(N2) suggest that the doubly 13C-substituted isotopomers should be detectable also. We want to determine the spectroscopic parameters of all three doubly 13C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. We investigated the laboratory rotational spectra of the three species between 150 and 990 GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sgr B2(N2). We modeled their emission as well as the emission of the 12C and singly 13C-substituted isotopologues assuming local thermodynamic equilibrium. We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three isotopomers. The quantum numbers ...

  13. Alteration of interaction between astrocytes and neurons in different stages of diabetes: a nuclear magnetic resonance study using [1-(13)C]glucose and [2-(13)C]acetate.

    Wang, Na; Zhao, Liang-Cai; Zheng, Yong-Quan; Dong, Min-Jian; Su, Yongchao; Chen, Wei-Jian; Hu, Zi-Long; Yang, Yun-Jun; Gao, Hong-Chang

    2015-01-01

    Increasing evidence has shown that the brain is a site of diabetic end-organ damage. This study investigates cerebral metabolism and the interactions between astrocytes and neurons at different stages of diabetes to identify the potential pathogenesis of diabetic encephalopathy. [1-(13)C]glucose or [2-(13)C]acetate is infused into 1- and 15-week diabetic rats, the brain extracts of which are analyzed by using (1)H and (13)C magnetic resonance spectroscopy. The (13)C-labeling pattern and enrichment of cerebral metabolites are also investigated. The increased (13)C incorporation in the glutamine, glutamate, and γ-aminobutyric acid carbons from [2-(13)C]acetate suggests that the astrocytic mitochondrial metabolism is enhanced in 1-week diabetic rats. By contrast, the decreased labeling from [1-(13)C]glucose reflected that the neuronal mitochondrial metabolism is impaired. As diabetes developed to 15 weeks, glutamine and glutamate concentrations significantly decreased. The increased labeling of glutamine C4 but unchanged labeling of glutamate C4 from [2-(13)C]acetate suggests decreased astrocyte supply to the neurons. In addition, the enhanced pyruvate recycling pathway manifested by the increased lactate C2 enrichment in 1-week diabetic rats is weakened in 15-week diabetic rats. Our study demonstrates the overall metabolism disturbances, changes in specific metabolic pathways, and interaction between astrocytes and neurons during the onset and development of diabetes. These results contribute to the mechanistic understanding of diabetes pathogenesis and evolution. PMID:25048983

  14. Determination of the 13C/12C ratio of ethanol derived from fruit juices and maple syrup by isotope ratio mass spectrometry: collaborative study.

    Jamin, Eric; Martin, Frédérique; Martin, Gilles G

    2004-01-01

    A collaborative study of the carbon-13 isotope ratio mass spectrometry (13C-IRMS) method based on fermentation ethanol for detecting some sugar additions in fruit juices and maple syrup is reported. This method is complementary to the site-specific natural isotope fractionation by nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in the same products (AOAC Official Methods 995.17 and 2000.19), and uses the same initial steps to recover pure ethanol. The fruit juices or maple syrups are completely fermented with yeast, and the alcohol is distilled with a quantitative yield (>96%). The carbon-13 deviation (delta13C) of ethanol is then determined by IRMS. This parameter becomes less negative when exogenous sugar derived from plants exhibiting a C4 metabolism (e.g., corn or cane) is added to a juice obtained from plants exhibiting a C3 metabolism (most common fruits except pineapple) or to maple syrup. Conversely, the delta13C of ethanol becomes more negative when exogenous sugar derived from C3 plants (e.g., beet, wheat, rice) is added to pineapple products. Twelve laboratories analyzed 2 materials (orange juice and pure cane sugar) in blind duplicate and 4 sugar-adulterated materials (orange juice, maple syrup, pineapple juice, and apple juice) as Youden pairs. The precision of that method for measuring delta13C was similar to that of other methods applied to wine ethanol or extracted sugars in juices. The within-laboratory (Sr) values ranged from 0.06 to 0.16%o (r = 0.17 to 0.46 percent per thousand), and the among-laboratories (SR) values ranged from 0.17 to 0.26 percent per thousand (R = 0.49 to 0.73 percent per thousand). The Study Directors recommend that the method be adopted as First Action by AOAC INTERNATIONAL. PMID:15287660

  15. Sc3CH@C80: selective (13)C enrichment of the central carbon atom.

    Junghans, Katrin; Rosenkranz, Marco; Popov, Alexey A

    2016-05-01

    Sc3CH@C80 is synthesized and characterized by (1)H, (13)C, and (45)Sc NMR. A large negative chemical shift of the proton, -11.73 ppm in the Ih and -8.79 ppm in the D5h C80 cage isomers, is found. (13)C satellites in the (1)H NMR spectrum enabled indirect determination of the (13)C chemical shift for the central carbon at 173 ± 1 ppm. Intensity of the satellites allowed determination of the (13)C content for the central carbon atom. This unique possibility is applied to analyze the cluster/cage (13)C distribution in mechanistic studies employing either (13)CH4 or (13)C powder to enrich Sc3CH@C80 with (13)C. PMID:27109443

  16. NMR spectroscopy of organic compounds of selenium and tellurium. Communication 9. Chemical shifts of 13C in isological series of unsaturated ethers, sulfides, selenides and tellurides

    The effects of heteroatoms Eh(Eh=O, S, Se, Te) on 13C chemical shifts in eleven isological series of R1-Eh-R2 unsaturated compounds are compared. A linear relation between 13C nuclei screening and tEh electronegativity is observed. An assumption is suggested that both likeness of the effects of 6A and 7A group elements on 13C chemical shifts of R1 and R2 substituents and their difference for elements of the 4A group are caused by unbonded interactions of the substituents with unshared electron pairs of heteroatoms

  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

    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. Citrate and Sugar Cofermentation in Leuconostoc oenos, a (sup13)C Nuclear Magnetic Resonance Study

    Ramos, A.; Santos, H.

    1996-01-01

    (sup13)C nuclear magnetic resonance spectroscopy was used to investigate citrate-glucose cometabolism in nongrowing cell suspensions of the wine lactic acid bacterium Leuconostoc oenos. The use of isotopically enriched substrates allowed us to identify and quantify in the end products the carbon atoms derived from each of the substrates supplied; furthermore, it was possible to differentiate between products derived from the metabolism of endogenous carbon reserves and those derived from exte...

  19. Plant diversity moderates drought stress in grasslands: Implications from a large real-world study on (13)C natural abundances.

    Klaus, Valentin H; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Solly, Emily F; Hänsel, Falk; Fischer, Markus; Kleinebecker, Till

    2016-10-01

    Land-use change and intensification play a key role in the current biodiversity crisis. The resulting species loss can have severe effects on ecosystem functions and services, thereby increasing ecosystem vulnerability to climate change. We explored whether land-use intensification (i.e. fertilization intensity), plant diversity and other potentially confounding environmental factors may be significantly related to water use (i.e. drought stress) of grassland plants. Drought stress was assessed using δ(13)C abundances in aboveground plant biomass of 150 grassland plots across a gradient of land-use intensity. Under water shortage, plants are forced to increasingly take up the heavier (13)C due to closing stomata leading to an enrichment of (13)C in biomass. Plants were sampled at the community level and for single species, which belong to three different functional groups (one grass, one herb, two legumes). Results show that plant diversity was significantly related to the δ(13)C signal in community, grass and legume biomass indicating that drought stress was lower under higher diversity, although this relation was not significant for the herb species under study. Fertilization, in turn, mostly increased drought stress as indicated by more positive δ(13)C values. This effect was mostly indirect by decreasing plant diversity. In line with these results, we found similar patterns in the δ(13)C signal of the organic matter in the topsoil, indicating a long history of these processes. Our study provided strong indication for a positive biodiversity-ecosystem functioning relationship with reduced drought stress at higher plant diversity. However, it also underlined a negative reinforcing situation: as land-use intensification decreases plant diversity in grasslands, this might subsequently increases drought sensitivity. Vice-versa, enhancing plant diversity in species-poor agricultural grasslands may moderate negative effects of future climate change. PMID:27220098

  20. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    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)

  1. Synthesis and GIAO NMR Calculations for Some Novel 4-Heteroarylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives: Comparison of Theoretical and Experimental 1Hand 13C- Chemical Shifts

    Haci Baykara

    2005-08-01

    Full Text Available Abstract: 3-Alkyl(aryl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1 reacted with 5-methylfuran-2-carboxyaldehyde to afford the corresponding 3-alkyl(aryl-4-(5-methyl-2-furylmethylenamino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2. Four newly synthesized compounds have been characterized by elemental analyses, IR, 1H-NMR, 13C-NMR and UV spectral data. In addition, isotropic 1H- and 13C-nuclear magnetic shielding constants of compounds 3 were calculated by employing the direct implementation of the gaugeincluding-atomic-orbital (GIAO method at the B3LYP density functional and HF levels of the theory. The geometry of each compound has been optimized using a 6-311G basis set. Nuclear shielding constants were also calculated by using 6-311G basis set. Theoretical values are compared to the experimental data.

  2. 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

    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...

  3. Global patterns in leaf 13C discrimination and implications for studies of past and future climate.

    Diefendorf, Aaron F; Mueller, Kevin E; Wing, Scott L; Koch, Paul L; Freeman, Katherine H

    2010-03-30

    Fractionation of carbon isotopes by plants during CO(2) uptake and fixation (Delta(leaf)) varies with environmental conditions, but quantitative patterns of Delta(leaf) across environmental gradients at the global scale are lacking. This impedes interpretation of variability in ancient terrestrial organic matter, which encodes climatic and ecological signals. To address this problem, we converted 3,310 published leaf delta(13)C values into mean Delta(leaf) values for 334 woody plant species at 105 locations (yielding 570 species-site combinations) representing a wide range of environmental conditions. Our analyses reveal a strong positive correlation between Delta(leaf) and mean annual precipitation (MAP; R(2) = 0.55), mirroring global trends in gross primary production and indicating stomatal constraints on leaf gas-exchange, mediated by water supply, are the dominant control of Delta(leaf) at large spatial scales. Independent of MAP, we show a lesser, negative effect of altitude on Delta(leaf) and minor effects of temperature and latitude. After accounting for these factors, mean Delta(leaf) of evergreen gymnosperms is lower (by 1-2.7 per thousand) than for other woody plant functional types (PFT), likely due to greater leaf-level water-use efficiency. Together, environmental and PFT effects contribute to differences in mean Delta(leaf) of up to 6 per thousand between biomes. Coupling geologic indicators of ancient precipitation and PFT (or biome) with modern Delta(leaf) patterns has potential to yield more robust reconstructions of atmospheric delta(13)C values, leading to better constraints on past greenhouse-gas perturbations. Accordingly, we estimate a 4.6 per thousand decline in the delta(13)C of atmospheric CO(2) at the onset of the Paleocene-Eocene Thermal Maximum, an abrupt global warming event approximately 55.8 Ma. PMID:20231481

  4. Design of a quadrature surface coil for hyperpolarized 13C MRS cardiac metabolism studies in pigs

    Giovannetti, G.; Frijia, F.; Hartwig, V.;

    2013-01-01

    coil performance evaluation in terms of coil resistance, sample-induced resistance and magnetic field pattern. Experimental SNR-vs.-depth profiles, extracted from the [1-13C]acetate phantom chemical shift image (CSI), showed good agreement with the theoretical SNR-vs.-depth profiles. Moreover, the...... performance of the quadrature coil was compared with the single TX/RX circular and TX/RX butterfly coil, in order to verify the advantage of the proposed configuration over the single coils throughout the volume of interest for cardiac imaging in pig. Finally, the quadrature surface coil was tested by...

  5. 13C/12C fractionation and its utility in terrestrial plant studies

    Carbon isotope ratios have proven useful in determination of the photosynthetic pathway of a plant species. In addition, the variation in isotopic values at both the interspecific and intraspecific levels has proven useful in understanding metabolic, environmental and life history patterns among plants. Of special interest is the use of carbon isotope ratios as a reliable indicator of plant water use efficiency. This chapter describes the basis for plant isotopic composition and then presents sampling protocol and procedures for the use of 13C/12C isotope ratio analysis for photosynthetic pathway determination, intercellular carbon dioxide determination, sugar, starch and cellulose extractions, on-line discrimination measurement and air sampling

  6. Study of cluster structure in 13C with AMD+HON-constraint method

    The 3α + n cluster states of 13C are discussed on the basis of antisymmetrized molecular dynamics with the constraint on the harmonic oscillator quanta. We predict two different kinds of the cluster states, the hoyle analogue state and the linear-chain state. The former is understood as the 0+2 state (Hoyle state) of 12C accompanied by a valence neutron occupying the s-wave. The latter constitute the parity doublet bands of Kπ = 1/2± owing to its parity asymmetric intrinsic structure

  7. Study of cluster structure in 13C with AMD+HON-constraint method

    Chiba, Yohei; Kimura, Masaaki

    2014-12-01

    The 3α + n cluster states of 13C are discussed on the basis of antisymmetrized molecular dynamics with the constraint on the harmonic oscillator quanta. We predict two different kinds of the cluster states, the hoyle analogue state and the linear-chain state. The former is understood as the 0+2 state (Hoyle state) of 12C accompanied by a valence neutron occupying the s-wave. The latter constitute the parity doublet bands of Kπ = 1/2± owing to its parity asymmetric intrinsic structure.

  8. Backbone and Ile-δ1, Leu, Val Methyl 1H, 13C and 15N NMR chemical shift assignments for human interferon-stimulated gene 15 protein

    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.

  9. Generic applications of (13) C-detected NMR diffusion to formulated systems with suppression of thermal convection induced by proton decoupling.

    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

  10. First Spectroscopic Studies and Detection in SgrB2 of 13C-DOUBLY Substitued Ethyl Cyanide

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.; Müller, Holger S. P.; Belloche, Arnaud

    2015-06-01

    Ethyl cyanide (CH_3CH_2CN) is one of the most abundant complex organic molecules in the interstellar medium firstly detected in OMC-1 and Sgr B2 in 1977. The vibrationally excited states are enough populated under ISM conditions and could be detected. Apart from the deuterated ones, all mono-substituted isotopologues of ethyl cyanide (13C and 15N have been detected in the ISM. The detection of isotopologues in the ISM is important: it can give information about the formation process of complex organic molecules, and it is essential to clean the ISM spectra from the lines of known molecules in order to detect new ones. The 12C/13C ratio found in SgrB2: 20-30 suggests that the doubly 13C could be present in the spectral line survey recently obtained with ALMA (EMoCA), but no spectroscopic studies exist up to now. We measured and analyzed the spectra of the 13C-doubly-substitued species up to 1 THz with the Lille solid-state based spectrometer. The spectroscopic results and and the detection of the doubly 13C species in SgrB2 will be presented. This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI. This work was also done under ANR-13-BS05-0008-02 IMOLABS. Support by the Deutsche Forschungsgemeinschaft via SFB 956, project B3 is acknowledged D.~R.~Johnson, et al., Astrophys.~J. 1977, 218, L370 A.~Belloche, et al., A&A 2013, 559, A47 A.M.~Daly, et al., Astrophys.~J. 2013, 768, 81 K.~Demyk, et al. A&A 2007 466, 255 Margulès, et al. A&A 2009, 493, 565 Belloche et al. 2014, Science, 345, 1584

  11. NMR methodologies for studying mitochondrial bioenergetics.

    Alves, Tiago C; Jarak, Ivana; Carvalho, Rui A

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is a technique with an increasing importance in the study of metabolic diseases. Its initial important role in the determination of chemical structures (1, 2) has been considerably overcome by its potential for the in vivo study of metabolism (3-5). The main characteristic that makes this technique so attractive is its noninvasiveness. Only nuclei capable of transitioning between energy states, in the presence of an intense and constant magnetic field, are studied. This includes abundant nuclei such as proton ((1)H) and phosphorous ((31)P), as well as stable isotopes such as deuterium ((2)H) and carbon 13 ((13)C). This allows a wide range of applications that vary from the determination of water distribution in tissues (as obtained in a magnetic resonance imaging scan) to the calculation of metabolic fluxes under ex vivo and in vivo conditions without the need to use radioactive tracers or tissue biopsies (as in a magnetic resonance spectroscopy (MRS) scan). In this chapter, some technical aspects of the methodology of an NMR/MRS experiment as well as how it can be used to study mitochondrial bioenergetics are overviewed. Advantages and disadvantages of in vivo MRS versus high-resolution NMR using proton high rotation magic angle spinning (HRMAS) of tissue biopsies and tissue extracts are also discussed. PMID:22057574

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

    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

  13. Experimental and theoretical NMR study of 4-(1-pyrrolidinylpiperidine

    Metin Bilge

    2011-12-01

    Full Text Available The possible stable forms and molecular structure of 4-(1-pyrrolidinylpiperidine (4-pypp have been studied experimentally and theoretically using nuclear magnetic resonance (NMR spectroscopy. 1H, 13C, 15N, DEPT, COSY and HETCOR NMR spectra of 4-pypp (C9H18N2 have been reported. Solvent effects on nuclear magnetic shielding tensors have been investigated using chloroform-d, methanol-d, acetone-d, dimethylsulfoxide-d and water-d. The magnitude of nJ(C,H (n = 1, 2, 3 coupling constants of 4-pypp have been determined with selective 1H decoupled 13C NMR techniques. 1H, 13C, 15N NMR chemical shifts and 1-3J(C,H coupling constants have also been calculated for the most stable two conformers, equatorial-equatorial (e-e and axial-equatorial (a-e forms of 4-pypp using DFT/6-311++G(d,p//6-31G(d level of theory. Results from experimental and theoretical data have showed that the molecular geometry and the mole fractions of stable conformers of 4-pypp are solvent dependent.

  14. Evaluation of a Thermodynamically Based Soil Microbial Decomposition Model Based on a 13c Tracer Study in Arctic Tundra Soils

    Zhu, X.; Tang, J.; Riley, W. J.; Wallenstein, M. D.; Cotrufo, M. F.; Machmuller, M. B.; Lynch, L.

    2014-12-01

    The incorporation of explicit representation of biological complexity in soil carbon decomposition models may improve our ability to accurately predict terrestrial carbon-climate feedbacks. A new generation of microbe-explicit soil decomposition models (MEMs) are being developed that represent soil biological complexity, but only a few take into account detailed biotic and abiotic components and competitive interactions in the complex soil system. In view of this, we have developed a thermodynamically based MEM with a detailed component network (polymeric organic carbon, dissolved organic carbon, microbes, extracellular enzymes, and mineral surfaces), in which competitive interactions and microbial metabolism are modeled using Equilibrium Chemistry Approximation kinetics and Dynamic Energy Budget theory, respectively. The model behavior has been tested and is qualitatively consistent with many empirical studies, but further evaluation of the model with field or lab experimental data in specific ecosystems is needed. Stable carbon isotope (13C) tracer experiments provide a means to directly evaluate soil carbon dynamics simulated by MEMs. In this study, we further develop the model to explicitly account for different carbon isotopes, including 13C and 14C. Isotopic fractionations in soil decomposition processes, including soil organic matter transformations and microbial metabolism, are considered. The 13C signals of different soil components derived from a 13C tracer experiment in Arctic tundra soils are used to test the model behavior and identify needed parametric and structural improvements. Our modeling and data comparison identify several key mechanisms that need to be included in MEMs. Finally, we present an analysis of the relative benefits and costs of additional complexity in MEMs compared to traditional pool-based modeling structures.

  15. 1H, 15N and 13C NMR resonance assignment, secondary structure and global fold of the FMN-binding domain of human cytochrome P450

    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

  16. Conditions to obtain precise and true measurements of the intramolecular 13C distribution in organic molecules by isotopic 13C nuclear magnetic resonance spectrometry

    Highlights: • Evaluation of the trueness and precision criteria of isotopic 13C NMR spectrometry. • Use of bi-labelled [1,2-13C2]acetic acid to determine the performance of the instrumental response. • Inter-calibration of the 13C intramolecular composition of acetic acid using the technique GC-Py–irm-MS. - Abstract: Intramolecular 13C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic 13C NMR spectrometry provides a general tool for measuring the position-specific 13C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal 13C distribution, and (ii) an approach to determining the “absolute” position-specific 13C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the 13C frequency range of the studied molecule, i.e. the chemical shift range. The “absolute value” and, therefore, the trueness of the 13C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH3 by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py–irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py–irm-MS (thus, the “true” value) while the other showed a bias, which was dependent to the range covered by the resonance frequencies of the

  17. Conditions to obtain precise and true measurements of the intramolecular {sup 13}C distribution in organic molecules by isotopic {sup 13}C nuclear magnetic resonance spectrometry

    Bayle, Kevin [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); Gilbert, Alexis [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); Julien, Maxime [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); Yamada, Keita [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Silvestre, Virginie; Robins, Richard J.; 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); 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); 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)

    2014-10-10

    Highlights: • Evaluation of the trueness and precision criteria of isotopic {sup 13}C NMR spectrometry. • Use of bi-labelled [1,2-{sup 13}C{sub 2}]acetic acid to determine the performance of the instrumental response. • Inter-calibration of the {sup 13}C intramolecular composition of acetic acid using the technique GC-Py–irm-MS. - Abstract: Intramolecular {sup 13}C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic {sup 13}C NMR spectrometry provides a general tool for measuring the position-specific {sup 13}C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal {sup 13}C distribution, and (ii) an approach to determining the “absolute” position-specific {sup 13}C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the {sup 13}C frequency range of the studied molecule, i.e. the chemical shift range. The “absolute value” and, therefore, the trueness of the {sup 13}C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH{sub 3} by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py–irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py–irm-MS (thus, the “true” value) while the other showed a bias, which was

  18. 1 H and 13 C NMR studies on the enoling of 5-benzyl barbituric acids

    This work shows that the derivatives of the 5-benzyl barbituric acids hydroxylated at the ortho position of the aromatic ring only exist in the enol form. and that the alkylation of this hydroxyl gives products which exist mainly in the ketone form of the DMSO

  19. The cerebral metabolism of amino acids and related metabolites as studied by {sup 13}C and {sup 14}C labelling

    Hassel, B.

    1995-11-01

    The present investigations show the feasibility of analyzing the cerebral metabolism of amino acids and related metabolites by {sup 13}C-and {sup 14}C-labelling using labelled acetate and glucose as markers for glial and neuronal metabolism, respectively. Using [{sup 13}C]acetate, it was shown that glial cells export {approx}60% of their TCA cycle intermediates, mostly as glutamine, and that this glutamine is used by neurons partly as an energy reserve, and partly it is converted directly to glutamate and GABA. Using [{sup 13}C]glucose, the glial process or pyruvate carboxylation was shown to compensate fully for the loss of glutamine. The mechanism of action of two neurotoxins, fluorocitrate and 3-nitropropionate was elucidated. The latter toxin was shown to inhibit the TCA cycle of GABAergic neurons selectively. Formation of pyruvate and lactate from glial TCA cycle intermediates was demonstrated in vivo. This pathway may be important for glial inactivation of transmitter glutamate and GABA. The results illustrate glianeuronal interactions, and they suggest the applicability of {sup 13}CNMR spectroscopy to the detailed study of the cerebral metabolism of amino acids in the intact, unanesthetized human brain. 174 refs.

  20. The cerebral metabolism of amino acids and related metabolites as studied by 13C and 14C labelling

    The present investigations show the feasibility of analyzing the cerebral metabolism of amino acids and related metabolites by 13C-and 14C-labelling using labelled acetate and glucose as markers for glial and neuronal metabolism, respectively. Using [13C[acetate, it was shown that glial cells export ∼60% of their TCA cycle intermediates, mostly as glutamine, and that this glutamine is used by neurons partly as an energy reserve, and partly it is converted directly to glutamate and GABA. Using [13C[glucose, the glial process or pyruvate carboxylation was shown to compensate fully for the loss of glutamine. The mechanism of action of two neurotoxins, fluorocitrate and 3-nitropropionate was elucidated. The latter toxin was shown to inhibit the TCA cycle of GABAergic neurons selectively. Formation of pyruvate and lactate from glial TCA cycle intermediates was demonstrated in vivo. This pathway may be important for glial inactivation of transmitter glutamate and GABA. The results illustrate glianeuronal interactions, and they suggest the applicability of 13CNMR spectroscopy to the detailed study of the cerebral metabolism of amino acids in the intact, unanesthetized human brain. 174 refs

  1. Phosphorus-31, 15N, and 13C NMR of glyphosate: Comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase

    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

  2. 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

    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.

  3. Synthesis and structural analysis of 13C-fatty acids

    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.

  4. Spectroscopic characteristic (FT-IR, FT-Raman, UV, 1H and 13C NMR), theoretical calculations and biological activity of alkali metal homovanillates

    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.

  5. A Large Scale Separation of Taxanes from the Bark Extract of Taxus yunnanesis and 1H- and 13C-NMR Assignments for 7-epi-10-Deacetyltaxol

    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.

  6. Structure of 13C studied by pion scattering near the [3,3] resonance

    Good resolution (π+,π+') and (π-,π-') data were obtained for many states in 13C using the Energetic Pion Channel and Spectrometer at the Los Alamos Meson Physics Facility. Differential cross sections were measured for angles between 200 and 1050 at an incident pion energy of 162 MeV for the elastic scattering as well as for states at excitation energies of 3.09, 3.68, 3.85, 7.55, 8.86, 9.5, 11.82, 16.05, 17.92, 21.37, and 21.6 MeV. Excitation functions were measured at momentum transfers of q = 1.1 h fm -1 and q = 1.4 h fm-1, for energies between 100 and 300 MeV. A sigma(π-)/sigma(π+) ratio of 9:1 was observed for the first time, indicating a pure neutron particle-hole excitation of a high spin state (J/sup π/ = 9/2+). Strikingly different energy dependences were found for ΔS = 0 and ΔS = 1 transitions. Data for all states were compared with the microscopic model calculations of Lee and Kurath. Very good agreement was found between experiment and theory for the strongly excited states and the 9/2+ state at 9.5 MeV, in sharp contrast to the disagreement for weak transitions. The excitation function data and comparisons with the microscopic model calculations were used to identify the states at 16.05, 17.92, 21.37, and 21.6 MeV as either 7/2+ or 9/2+ states. The elastic scattering data were analyzed with an optical modeland the results were found to be consistent with neutron and proton distributions having equal rms radii. The optical potentials generated were used in a collective model analysis of the 3/2- (3.68 MeV) and 5/2- (7.55 MeV) states. The reduced transition probabilities (B(E2)) derived from the proton parts of the transition strength are in agreement with those determined from electromagnetic measurements

  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

    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.

  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

    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.

  9. 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

    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...

  10. Isotopic finger-printing of active pharmaceutical ingredients by 13C NMR and polarization transfer techniques as a tool to fight against counterfeiting.

    Bussy, Ugo; Thibaudeau, Christophe; Thomas, Freddy; Desmurs, Jean-Roger; Jamin, Eric; Remaud, Gérald S; Silvestre, Virginie; Akoka, Serge

    2011-09-30

    The robustness of adiabatic polarization transfer methods has been evaluated for determining the carbon isotopic finger-printing of active pharmaceutical ingredients. The short time stabilities of the adiabatic DEPT and INEPT sequences are very close to that observed with the one pulse sequence, but the DEPT long time stability is not sufficient for isotopic measurements at natural abundance or low enrichment. Using the INEPT sequence for (13)C isotopic measurements induces a dramatic reduction in the experimental time without deterioration in short time or long time stability. It appears, therefore, to be a method of choice for obtaining the isotopic finger-print of different ibuprofen samples in a minimum time. The results obtained on 13 commercial ibuprofen samples from different origins show that this strategy can be used effectively to determine (13)C distribution within a given molecule and to compare accurately differences in the isotopic distribution between different samples of the given molecule. The present methodology is proposed as a suitable tool to fight against counterfeiting. PMID:21872037

  11. 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.

    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

  12. Solid state NMR study of cumbaru flour

    The polysaccharide obtained by seed of Dipteryx alata Vog, has been characterised by 13C solid state, using the basic routine techniques, like MAS and CPMAS and by the proton spin-lattice relaxation time in the rotating frame parameter (T1Hρ). Knowing that the chemical structure and molecular dynamic are extremely necessary route to obtain information on the polysaccharides, this work contributes to the classification of the seed containing in the cumbaru fruit to get response on its application. To obtain the initial responses for our purposes some solid state NMR techniques were chosen. The CPMAS 13C NMR spectrum of the polysaccharide was investigated to know if it has some crystallinity. The MAS 13C NMR spectrum showed the presence of domains with distinct molecular mobility, because these domains will differ basically in the distribution size and chain packing. The variable contact time experiment was used to analyse the distribution form of 13C decays, which give us more information about sample heterogeneity. The T1HρHr values were obtained from the variable contact time and by delayed contact time experiment, because these parameter indicate the order of polysaccharides. From the values of this parameter, we found that this polysaccharide is completely non-ordered. (author)

  13. Study on dynamic change of soil organic matter during corn stalk decomposition by δ13C method

    Sen, Dou; Jin-Jing, Zhang; Lichtfouse, Eric; Ya-Cheng, Cao

    2003-01-01

    National audience In an incubation experiment, dynamic change in amounts of soil organic matter (SOM), HA and FA were studied during corn stalk (CS) decomposition in dark-brown soil by δ13C method. The results showed that organic carbon from both new added CS and original soil decreased, but decomposition rate of the latter was slower than that of the former during incubation periods. The residual rate of CS was about 36% at 360th day and 24% at 720th day, whereas that of original SOM was ...

  14. Post-mortem changes in porcine M. longissimus studied by solid-state 13C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy.

    Bertram, Hanne Christine; Jakobsen, Hans Jørgen; Andersen, Henrik Jørgen; Karlsson, Anders Hans; Engelsen, Søren Balling

    2003-03-26

    Solid-state (13)C cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) experiments are carried out for the first time on rapidly frozen muscle biopsies taken in M. longissimus in vivo and at 1 min, 45 min, and 24 h post-mortem from three pigs. Two of the pigs were CO(2)-stunned (control animals), and one was pre-slaughter-stressed (treadmill exercise) followed by electrical stunning to induce difference in metabolism post-mortem. (13)C resonance signals from saturated and unsaturated carbons in fatty acids, carboxylic carbons, and carbons in lactate and glycogen are identified in the solid-state NMR spectra. The (13)C CP MAS spectra obtained for post-mortem samples of the stressed, electrically stunned pig differ significantly from the post-mortem control samples, as the intensity of a resonance line appearing at 30 ppm, assigned to carbons of the methylene chains, is reduced for the stressed pig. This spectral difference is probably due to changes in lipid mobility and indicates altered membrane properties in the muscle of the stressed/electrically stunned animal when compared with the control animals already 1 min post-mortem. In addition, the post-mortem period changes in glycogen carbons can be estimated from the (13)C CP MAS spectra, yielding a correlation of r = 0.74 to subsequent biochemical determination of the glycogen content. PMID:12643674

  15. Solid-state NMR study of fluorinated steroids.

    Yang, Kai-Jay; Lin, Su-Ching; Huang, Shing-Jong; Ching, Wei-Min; Hung, Chen-Hsiung; Tzou, Der-Lii M

    2014-02-01

    Solid-state {(1)H}(13)C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy was performed to analyze two fluorinated steroids, i.e., betamethasone (BMS) and fludrocortisone acetate (FCA), that have fluorine attached to C9, as well as two non-fluorinated analogs, i.e., prednisolone (PRD) and hydrocortisone 21-acetate (HCA). The (13)C signals of BMS revealed multiplet patterns with splittings of 16-215Hz, indicating multiple ring conformations, whereas the (13)C signals of FCA, HCA, and PRD exhibited only singlet patterns, implying a unique conformation. In addition, BMS and FCA exhibited substantial deviation (>3.5ppm) in approximately half of the (13)C signals and significant deviation (>45ppm) in the (13)C9 signal compared to PRD and HCA, respectively. In this study, we demonstrate that fluorinated steroids, such as BMS and FCA, have steroidal ring conformation(s) that are distinct from non-fluorinated analogs, such as PRD and HCA. PMID:24316163

  16. Analysis of commercial proanthocyanidins. Part 4: solid state (13)C NMR as a tool for in situ analysis of proanthocyanidin tannins, in heartwood and bark of quebracho and acacia, and related species.

    Reid, David G; Bonnet, Susan L; Kemp, Gabre; van der Westhuizen, Jan H

    2013-10-01

    (13)C NMR is an effective method of characterizing proanthocyanidin (PAC) tannins in quebracho (Schinopsis lorentzii) heartwood and black wattle (Acacia mearnsii) bark, before and after commercial extraction. The B-rings of the constituent flavan-3-ols, catechols (quebracho) or pyrogallols (wattle), are recognized in unprocessed source materials by "marker" signals at ca. 118 or 105ppm, respectively. NMR allows the minimum extraction efficiency to be calculated; ca. 30%, and ca. 80%, for quebracho heartwood and black wattle bark, respectively. NMR can also identify PAC tannin (predominantly robinetinidin), and compare tannin content, in bark from other acacia species; tannin content decreases in the order A. mearnsii, Acacia pycnantha (87% of A. mearnsii), Acacia dealbata and Acacia decurrens (each 74%) and Acacia karroo (30%). Heartwood from an underexploited PAC tannin source, Searsia lancea, taxonomically close to quebracho, shows abundant profisetinidin and catechin PACs. NMR offers the advantage of being applicable to source materials in their native state, and has potential applications in optimizing extraction processes, identification of tannin sources, and characterization of tannin content in cultivar yield improvement programmes. PMID:23838626

  17. 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

    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.

  18. 13C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations

    Anna Kasicka-Jonderko; Anna Nita; Krzysztof Jonderko; Magdalena Kami(n)ska; Barbara B(l)o(n)ska-Fajfrowska

    2011-01-01

    AIM: To find the most reproducible quantitative parameter of a standard 13C-methacetin breath test (13C-MBT).METHODS: Twenty healthy volunteers (10 female, 10 male) underwent the 13C-MBT after intake of 75 mg 13C-methacetin p.o. on three occasions. Short- and medium-term reproducibility was assessed with paired examinations taken at an interval of 2 and 18 d (medians), respectively.RESULTS: The reproducibility of the 1-h cumulative 13C recovery (AUC0-60), characterized by a coefficient of variation of 10%, appeared to be considerably better than the reproducibility of the maximum momentary 13C recovery or the time of reaching it. Remarkably, as opposed to the short gap between consecutive examinations, the capacity of the liver to handle 13C-methacetin increased slightly but statistically significantly when a repeat dose was administered after two to three weeks. Regarding the AUC0-60, the magnitude of this fixed bias amounted to 7.5%. Neither the time gap between the repeat examinations nor the gender of the subjects affected the 13C-MBT reproducibility. CONCLUSION: 13C-MBT is most reproducibly quantified by the cumulative 13C recovery, but the exactitude thereof may be modestly affected by persistent stimulation of CYP1A2 on repeat examinations.

  19. Blends of natural rubber and polyurethane lattices studied by solid-state NMR

    Molecular mixing in films formed from a mixture of a polyurethane and natural rubber lattices has been studied using 1H and 13C solid-state NMR. The techniques employed include 1H relaxation measurements, and 13C cross-polarisation and direct excitation methods. The spectra of the blends were essentially a weighted superposition of the spectra of the individual components, indicating that the polyurethane and rubber remained phase-separated in large domains. (author)

  20. Metabolic fate of fructose in human adipocytes: a targeted 13C tracer fate association study

    Varma, Vijayalakshmi; Boros, László G; Nolen, Greg T.; Chang, Ching-Wei; Wabitsch, Martin; Beger, Richard D.; Kaput, Jim

    2014-01-01

    The development of obesity is becoming an international problem and the role of fructose is unclear. Studies using liver tissue and hepatocytes have contributed to the understanding of fructose metabolism. Excess fructose consumption also affects extra hepatic tissues including adipose tissue. The effects of fructose on human adipocytes are not yet fully characterized, although in vivo studies have noted increased adiposity and weight gain in response to fructose sweetened-beverages. In order...

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

    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

  2. Synthesis of 13C-labeled methanol

    A novel convenient method for the synthesis of 13C-methanol was described. 13C- methanol was prepared by means of catalytic hydrogenation, and then as-synthesized methanol solution was further purified in a microscale high-efficient rectification column. The chemical purity of 13C-methanol was more than 99.5%. The synthetic route was featured by mild conditions and high yields of more than 90% based on isotopic substrate consumed. The product was characterized by GC-MS and 1H NMR, and the 13C abundance of 13C- methanol was more than 97%. Compared with the raw materials, the reduction of relative isotopic abundance of product was less than 1%. (authors)

  3. Influence of the nature of soil organic matter on the sorption behaviour of pentadecane as determined by PLS analysis of mid-infrared DRIFT and solid-state 13C NMR spectra

    The nature of soil organic matter (SOM) functional groups associated with sorption processes was determined by correlating partitioning coefficients with solid-state 13C nuclear magnetic resonance (NMR) and diffuse reflectance mid-infrared (DRIFT) spectral features using partial least squares (PLS) regression analysis. Partitioning sorption coefficients for n-pentadecane (n-C15) were determined for three alternative models: the Langmuir model, the dual distributed reactive domain model (DRDM) and the Freundlich model, where the latter was found to be the most appropriate. NMR-derived constitutional descriptors did not correlate with Freundlich model parameters. By contrast, PLS analysis revealed the most likely nature of the functional groups in SOM associated with n-C15 sorption coefficients (KF) to be aromatic, possibly porous soil char, rather than aliphatic organic components for the presently investigated soils. High PLS cross-validation correlation suggested that the model was robust for the purpose of characterising the functional group chemistry important for n-C15 sorption. - NMR/IR spectroscopy and chemometrics reveal the aromatic fraction of soil organic matter being responsible for alkane sorption.

  4. Organometallic derivatives of furan. LII. Synthesis of carbofunctional furylsilanes and their 1H, 13C, and 29Si NMR spectroscopic and quantum-chemical investigation

    Under the standard conditions for the synthesis of furan compounds it is possible to obtain the carbofunctional derivatives of silylated furfural with retention of the trimethylsilyl group in the ring. By NMR and CNDO/2 LCAO MO methods and also as a result of the investigation of the chemical characteristics of silylated furfural and its carbofunctional derivatives it was established that the introduction of a trimethylsilyl group at position 5 of the furan ring does not change the reactivity of the carbofunctional substituents at position 2. The electronic effects of the substituents are hardly transmitted through the furan ring at all. The effect of substituents in the carbofunctional furylsilanes on the electronic structure of the ring is additive

  5. Probing structural patterns of ion association and solvation in mixtures of imidazolium ionic liquids with acetonitrile by means of relative (1)H and (13)C NMR chemical shifts.

    Marekha, Bogdan A; Kalugin, Oleg N; Bria, Marc; Idrissi, Abdenacer

    2015-09-21

    Mixtures of ionic liquids (ILs) with polar aprotic solvents in different combinations and under different conditions (concentration, temperature etc.) are used widely in electrochemistry. However, little is known about the key intermolecular interactions in such mixtures depending on the nature of the constituents and mixture composition. In order to systematically address the intermolecular interactions, the chemical shift variation of (1)H and (13)C nuclei has been followed in mixtures of imidazolium ILs 1-n-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4), 1-n-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), 1-n-butyl-3-methylimidazolium trifluoromethanesulfonate (BmimTfO) and 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimTFSI) with molecular solvent acetonitrile (AN) over the entire composition range at 300 K. The concept of relative chemical shift variation is proposed to assess the observed effects on a unified and unbiased scale. We have found that hydrogen bonds between the imidazolium ring hydrogen atoms and electronegative atoms of anions are stronger in BmimBF4 and BmimTfO ILs than those in BmimTFSI and BmimPF6. Hydrogen atom at position 2 of the imidazolium ring is substantially more sensitive to interionic hydrogen bonding than those at positions 4-5 in the case of BmimTfO and BmimTFSI ILs. These hydrogen bonds are disrupted upon dilution in AN due to ion dissociation which is more pronounced at high dilutions. Specific solvation interactions between AN molecules and IL cations are poorly manifested. PMID:26278514

  6. Titration and exchange studies of liver fatty acid-binding protein with 13C-labeled long-chain fatty acids.

    Wang, Hsin; He, Yan; Kroenke, Christopher D; Kodukula, Sarala; Storch, Judith; Palmer, Arthur G; Stark, Ruth E

    2002-04-30

    Uniformly (13)C-labeled long-chain fatty acids were used to probe ligand binding to rat liver fatty acid-binding protein (LFABP), an atypical member of the fatty acid-binding protein (FABP) family that binds more than one molecule of long-chain fatty acid, accommodates a variety of diverse ligands, and exhibits diffusion-mediated lipid transport to membranes. Two sets of (1)H-(13)C resonances were found in a titration series of NMR spectra for oleate-LFABP complexes, indicating that two molecules of the fatty acid are situated in the protein cavity. However, no distinct resonances were observed for the excess fatty acid in solution, suggesting that at least one ligand undergoes rapid exchange with oleate in the bulk solution. An exchange rate of 54 +/- 6 s(-1) between the two sets of resonances was measured directly using (13)C z,z-exchange spectroscopy. In light of these NMR measurements, possible molecular mechanisms for the ligand-exchange process are evaluated and implications for the anomalous fatty acid transport mechanism of LFABP are discussed. PMID:11969406

  7. NMR study of some coumarins and furocoumarins methylated

    Miranda, R.; Santana, L.; Uriarte, E.; Zagotto, G.

    1994-01-01

    The 1H and 13C NMR spectra of various methylcoumarins and methylfurocoumarins are reported. All signals were assigned and the influence on chemical shifts of methylation at various positions was determined.

  8. 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

    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.

  9. {sup 13}C NMR hyperfine couplings, {ital T}{sub 1} anisotropy, and Korringa relations in Rb{sub 2}CsC{sub 60}: Search for effects of strong correlation

    Pennington, C.H.; Stenger, V.A.; Recchia, C.H.; Hahm, C.; Gorny, K.; Nandor, V. [Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, Ohio 43210 (United States); Buffinger, D.R.; Lee, S.M.; Ziebarth, R.P. [Department of Chemistry, The Ohio State University, 120 West 18th Avenue, Columbus, Ohio 43210 (United States)

    1996-02-01

    Initial considerations lead one to suspect that effects of strong correlation might be present in the alkali fulleride superconductors. We report {ital direct} measurements of {sup 13}C {ital T}{sub 1} anisotropy at 80 K in Rb{sub 2}CsC{sub 60} and compare, in the context of the Korringa relation, the inferred spin-dipolar contribution to 1/{ital T}{sub 1} with the widths of the measured powder pattern line shape. The results demonstrate that the Korringa relation, valid in the limit of noninteracting electrons, holds in this case. Taken together with other normal-state NMR behavior this result makes important effects of strong correlation appear unlikely. {copyright} {ital 1996 The American Physical Society.}

  10. 1H and 13C NMR spectra, structure and physicochemical features of phenyl acridine-9-carboxylates and 10-methyl-9-(phenoxycarbonyl)acridinium trifluoromethanesulphonates--alkyl substituted in the phenyl fragment.

    Krzymiński, K; Malecha, P; Zadykowicz, B; Wróblewska, A; Błażejowski, J

    2011-01-01

    The 1H and 13C NMR spectra of twelve phenyl acridine-9-carboxylates--alkyl-substituted in the phenyl fragment--and their 10-methyl-9-(phenoxycarbonyl)acridinium salts dissolved in CD3CN, CD3OD, CDCl3 and DMSO-d6 were recorded in order to examine the influence of the structure of these compounds and the properties of the solvents on chemical shifts and 1H-(1)H coupling constants. Experimental data were compared with 1H and 13C chemical shifts predicted at the GIAO/DFT level of theory for DFT(B3LYP)/6-31G** optimised geometries of molecules, as well as with values of 1H chemical shifts and 1H-(1)H coupling constants, estimated using ACD/HNMR database software to ensure that the assignment was correct. To investigate the relations between chemical shifts and selected structural or physicochemical characteristics of the target compounds, the values of several of these parameters were determined at the DFT or HF levels of theory. The HOMO and LUMO energies obtained at the HF level yielded the ionisation potentials and electron affinities of molecules. The DFT method provided atomic partial charges, dipole moments, LCAO coefficients of pz LUMO of selected C atoms, and angles reflecting characteristic structural features of the compounds. It was found that the experimentally determined 1H and 13C chemical shifts of certain atoms relate to the predicted dipole moments, the angles between the acridine and phenyl moieties, and the LCAO coefficients of the pz LUMO of the C atoms believed to participate in the initial step of the oxidation of the target compounds. The spectral and physicochemical characteristics of the target compounds were investigated in the context of their chemiluminogenic ability. PMID:21134782

  11. Backbone dynamics of a model membrane protein: measurement of individual amide hydrogen-exchange rates in detergent-solubilized M13 coat protein using 13C NMR hydrogen/deuterium isotope shifts

    Hydrogen-exchange rates have been measured for individual assigned amide protons in M13 coat protein, a 50-residue integral membrane protein, using a 13C nuclear magnetic resonance (NMR) equilibrium isotope shift technique. The locations of the more rapidly exchanging amides have been determined. In D2O solutions, a peptide carbonyl resonance undergoes a small upfield isotope shift (0.08-0.09 ppm) from its position in H2O solutions; in 1:1 H2O/D2O mixtures, the carbonyl line shape is determined by the exchange rate at the adjacent nitrogen atom. M13 coat protein was labeled biosynthetically with 13C at the peptide carbonyls of alanine, glycine, phenylalanine, proline, and lysine, and the exchange rates of 12 assigned amide protons in the hydrophilic regions were measured as a function of pH by using the isotope shift method. This equilibrium technique is sensitive to the more rapidly exchanging protons which are difficult to measure by classical exchange-out experiments. In proteins, structural factors, notably H bonding, can decrease the exchange rate of an amide proton by many orders of magnitude from that observed in the freely exposed amides of model peptides such as poly(DL-alanine). With corrections for sequence-related inductive effects, the retardation of amide exchange in sodium dodecyl sulfate solubilized coat protein has been calculated with respect to poly(DL-alanine). The most rapidly exchanging protons, which are retarded very little or not at all, are shown to occur at the N- and C-termini of the molecule. A model of the detergent-solubilized coat protein is constructed from these H-exchange data which is consistent with circular dichroism and other NMR results

  12. Infrared and NMR (1H & 13C) Spectra of Sodium Salts of N-Bromo-Mono and Di-Substituted-Benzenesulphonamides

    Gowda, B. Thimme; Usha, K. M.

    2003-06-01

    Fifteen sodium salts of mono and di-substituted N-bromobenzene-sulphonamides of the configuration, 4-X-C6H4SO2NaNBr (where X = H; CH3; C2H5; F; Cl; Br; or NO2) and i-X,j- YC6H3SO2NaNBr (where i-X, j-Y = 2,3-(CH3)2; 2,4-(CH3)2; 2,5-(CH3)2; 2-CH3,4-Cl; 2-CH3,5-Cl; 3-CH3,4-Cl; 2,4-Cl2 or 3,4-Cl2) are prepared and characterised by measuring their infrared spectra in the solid state and NMR spectra in solution. The N-Br vibrational frequencies, νN-Br of N-bromoarylsulphonamides vary in the range, 945 - 925 cm-1, while the N-Cl vibrational frequencies, νN-Cl, are observed in the range 950 - 927 cm-1 for the corresponding N-chloroarylsulphonamides. Asymmetric and symmetric SO2 stretching vibrations appear in the ranges, 1391 - 1352 cm-1 and 1148 - 1131 cm-1 for the monosubstituted N-bromoarylsulphonamides, while for the disubstituted N-bromocompounds they absorb in the ranges 1391 - 1331 cm-1 and 1149 - 1121 cm-1, respectively. The chemical shifts of aromatic protons and carbon-13 in all the N-bromoarylsulphonamides have been calculated by adding substituent contributions to the shift of benzene and compared with the observed values. The agreement between the calculated and experimental chemical shifts for different protons or carbon-13 is quite good.

  13. NMR Dynamic Studies in Living Systems

    闫永彬; 范明杰; 罗雪春; 张日清

    2002-01-01

    Nuclear magnetic resonance (NMR) can noninvasively monitor the intracellular concentrations and kinetic properties of numerous inorganic and organic compounds. These characteristics have made NMR a useful tool for dynamic studies of living systems. Applications of NMR to living systems have successfully extended to many areas, including studies of metabolic regulation, ion transport, and intracellular reaction rates in vivo. The major purpose of this review is to summarize the results that can be obtained by modern NMR techniques in living systems. With the advances of new techniques, NMR measurements of various nuclides have been performed for specific physiological purposes. Although some technical problems still remain and there are still discrepancies between NMR and traditional biochemical results, the abundant and unique information obtained from NMR spectra suggests that NMR will be more extensively applied in future studies of living systems. The fast development of these new techniques is providing many new NMR applications in living systems, as well as in structural biology.

  14. NMR studies of transmembrane electron transport in human erythrocytes

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

  15. 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

    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 forest floor (FF) and 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

  16. Study of the (d,α) reactions on the nuclei 10B, 11B, 12C, and 13C and the reaction 13C(p,α)10B and their microscopic and semicroscopic analysis

    In the framework of a systematic analysis of many-particle transfer reactions on light nuclei in the present thesis the two-particle transfer reactions of the type (d,α) on the nucleus 10B at Esub(d) = 16 MeV and on the nuclei 11B, 12C and 13C at Esub(d) = 24 MeV as well as the three-particle transfer reaction 13C(p,α)10B at eight incident energies between 16 and 45 MeV have been studied. In the case of the residual nuclei 10B and 11B transitions up to an excitation energy Esub(x) approx.= 7.5 respectively approx.= 9,0 MeV, in the case of the residual nuclei 8Be and 9Be transitions up to Esub(x) approx.= 17 respectively 2.5 MeV were evaluated. Under the assumption that the studied reactions behave as direct one-stage transfer processes the measurement results were analyzed in the framework of the DWBA theory in zero-range approximation. The parameters for the optical potentials used in the DWBA calculations were taken from literature and partly modified by fitting to the angular distributions of the reactions studied here. Microscopic and semimicroscopic calculations were performed. In the semimicroscopic calculations the spectroscopic amplitudes calculated microscopically or in SU(3) approximation were used together with a cluster form factor, in the other case with a microscopically calculated form factor. For the residual nucleus for some higher excited states results on spin, parity, and isospin could be partly obtained, partly confirmed. (orig./HSI)

  17. NMR Studies of Inclusion Compounds

    Nikkhou Aski, Sahar

    2008-01-01

    This thesis presents the application of some of the NMR methods in studying host-guest complexes, mainly in solution. The general focus of the work is on investigating the reorientational dynamics of some small molecules that are bound inside cavities of larger moieties. In the current work, these moieties belong to two groups: cryptophanes and cyclodextrins. Depending on the structure of the cavities, properties of the guest molecules and the formed complexes vary. Chloroform and dichloromet...

  18. Carbon-13 NMR studies of liquid crystals

    High resolution, proton decoupled 13C nmr are observed for a series of neat nematic liquid crystals, the p-alkoxyazoxybenzenes, and a smectic-A liquid crystal, diethylazoxydibenzoate in a magnetic field of 23 kG. The (uniaxial) order parameters S = less than P2(costheta) greater than are found to be about 0.4 and 0.9 for the nematic and smectic-A phase respectively at the clearing points. The order parameter increases with decreasing temperature in the nematic phase but is constant, or nearly so, with temperature in the smectic-A phase. In the nematic series studied, the ordering exhibits an even-odd alternation along the series and qualitative agreement with a recent theory due to Marcelja is found. In both phases, the spectra show that the molecule rotates rapidly about its long axis. Tentative conclusions about molecular conformational motion and 14N spin relaxation are presented for both nematic and smectic-A phases. In the smectic-A phase, the sample is rotated about an axis perpendicular to H0 and the resulting spectra are dicusssed. The theory of observed chemical shifts in liquid crystals is discussed and equations are derived which relate the nmr spectra of liquid-crystals to the order parameters. A model for the smectic-C phase due to Luz and Meiboom and Doane is described and lineshapes are determined on the basis of this model for special cases. The dependence of the order parameters on the molecular potential which give rise to the various degrees of order in the different liquid crystalline phases is examined. To a good approximation the functional dependence of the order parameters on the molecular potential is shown to be a simple one in the limit of small tilt angle in the smectic-C phase

  19. Studies on 13C isotope discrimination for identifying tree provenances efficient in water use under water deficit conditions in Kenya

    Screening for drought resistance traits was conducted in a semi-arid site in Machakos using 11 provenances of Acacia tortilis, 6 provenances of Prosopis juliflora and 4 provenances of Casuarina equisetifolia. Tolerance to drought was assessed by the 13C isotope discrimination (Δ) technique as well as by determining the waster use efficiency (WUE). Measurements of dry matter and early growth performance were also taken as indicators of drought resistance. The results showed significant differences in the 13C Isotope discrimination, water use efficiency and dry matter yields by the different provenances tested. Generally, the results indicated that there were significant linear negative relationships between 13C discrimination with water use efficiency as well as dry matter yield. The results further showed highly significant positive relationship between dry matter yield and water use efficiency. Acacia tortilis provenances from middle East and neighbouring North Eastern Africa region appear to possess the greatest abilities for drought resistance in comparison with those from sub-saharan Africa as indicated by their 13C Isotope discrimination levels, dry matter yield and water use efficiency. However, Acacia provenance from Israel had the highest drought resistance trail. Prosopis provenance from Costa Rica and Casuarina from Dakar region in Senegal also emerged as the best provenances in terms of drought tolerance as shown by the 13C isotope discrimination and dry matter traits. (author). 8 refs, 4 figs, 3 tabs

  20. Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling

    Cabin-Flaman, Armelle; Monnier, Anne-Francoise; Coffinier, Yannick; Audinot, Jean-Nicolas; Gibouin, David; Wirtz, Tom; Boukherroub, Rabah; Migeon, Henri-Noël; Bensimon, Aaron; Jannière, Laurent; Ripoll, Camille; Norris, Victor

    2016-01-01

    Dynamic secondary ion mass spectrometry ( D-SIMS) imaging of combed DNA – the combing, imaging by SIMS or CIS method – has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to 13C-labeling via the detection and quantification of the 13C 14N - recombinant ion and the use of the 13C: 12C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS. PMID:27429742

  1. Study on the differential cross sections of the (d, 7Li)-reactions on 13C nuclei

    Differential cross sections of 13C(d, 7Li)8Be and 13C(d, sup(7)Li*sub(0.478))sup(8)Be on 13.6 MeV deuteron cyclotron beam using the ΔExE technique to identify reaction products, in which silicon ΔE detectors, of approximately 5 mk thickness were applied, have been measured. Experimental data have been analyzed according to the Hauser- Feshbach statistical theory and in the approximation of distorted waves with account for finitude of interaction and recoil radius. It is shown that angular distributions of 7Li and sup(7)Li*sub(0.478) ions are described most satisfactorily in the approximation of direct transfer of 5He quasicluster from 2Dsub(1/2) state of 13C nucleus into 2Ssub(3/2) state of 7Li, sup(7)Li*sub(0.478) nuclei

  2. NMR studies of fructose-1,6-bisphosphate aldolase from E. coli

    Previous NMR studies of intact E. coli showed that during steady state anaerobic catabolism of glucose the main glycolytic intermediate detectable in these cells is fructose-1,6-bisphosphate (FBP), levels of which remain constant while the levels of glucose, lactate and succinate vary considerably. Upon feeding these cells glucose labeled with 13C at the C1 or C6 position, the level of scrambling of label between the C1 and C6 positions of FBP was low suggesting that the FBP-aldolase reaction is far from equilibrium. In order to account for these observations, a study was undertaken on FBP-aldolase from this organism. This enzyme is a dimeric Zn++ metalloenzyme with a M/sub r/ of 80,000. It was purified in gram quantities from an overproducer strain and was characterized by standard biochemical techniques prior to the NMR studies. 13C NMR experiments were conducted using [2-13C]dihydroxyacetone phosphate (DHAP) and [2,5-13C]fructose-1,6-biphosphate (FBP). Since these substrates can exist in solution in a number of interconvertible forms, the initial experiments determined the relative amounts of these forms and the rates of their interconversion. Subsequently, NMR experiments with the purified enzyme were conducted. Based upon these results, the author concludes that in E. coli the FBP-alkolase reaction appears to be the rate limiting step of anaerobic glycolysis

  3. {sup 1} H and {sup 13} C NMR of phenyl barbiturilidene; RMN de H-1 e C-13 de fenil barbiturilidenos

    Villar, Jose Daniel Figueroa; Santos, Nedina Lucia dos; Cruz, Elizabete Rangel [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

    1991-12-31

    The condensation of barbituric acids with aromatic aldehydes gives the phenyl barbiturilidenes, which are studied as intermediary compounds in the synthesis of new heterocyclic compounds for pharmaceutical use. One of the most characteristic reactions of these compounds is the Michael type addition reaction, in the exocyclic carbon-carbon double binding. The reaction with 2,4-di nitrophenyl hydrazine reaction is been used as a test of this type of reactivity, which supplies the respective hydrazone and barbituric acid. In this work, preliminary studies have been performed for establishing correlations between the Brown parameter ({sigma}{sup +}), the chemical shifts ({delta}) of the barbiturilidene atoms involved in the reaction, and their reactivities 3 refs., 1 fig., 6 tabs.

  4. Effect of organic carbon chemistry on sorption of atrazine and metsulfuron-methyl as determined by (13)C-NMR and IR spectroscopy.

    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

  5. NMR study of vortex dynamics in LuNi2B2C

    11B- and 13C-pulsed nuclear magnetic resonance (NMR) measurements have been performed on two single crystals of LuNi2B2C and LuNi2B213C superconductors to investigate the vortex dynamics. 11B NMR for the unenriched crystal, LuNi2B2C, shows a single peak. All data of 11B NMR exhibit significant features characteristic of vortex lattice and fluctuation. On the other hand, 13C NMR for the enriched crystal, LuNi2B213C, evolves to double peaks below Tc. All NMR data for the broad peak of 13C NMR are consistent with those of 11B NMR indicating that this part comes from a superconducting phase. On the contrary, the narrow peak of 13C NMR is found to originate from an impure phase. This suggests that crystallinity is deteriorated during 13C enrichment into the crystal

  6. 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

    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.

  7. Quantification of 1-(13) C-L-methionine in rat serum with hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry and its application in pharmacokinetic study.

    Xu, Ying; Huang, Xiao; Nie, Xiuli; Yang, Li; Yan, Weili; Wang, Zhengtao; Wang, Changhong; Hu, Zhibi

    2011-09-01

    A rapid, selective and sensitive hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry (MS/MS) method was developed to determine 1-(13) C-l-methionine in rat serum. Proteins in serum were precipitated using acetonitrile and the supernatant was separated after centrifugation. 1-(13) C-l-phenylalnine was used as the internal standard. HILIC-tandem mass spectrometry analysis was performed on a hydrophilic interaction silica column (TSK-GEL AMIDE-80) using a linear gradient elution system, acetonitrile-5 mm ammonium acetate containing 0.1% formic acid and multiple reaction monitoring mode for 1-(13) C-l-methionine and 1-(13) C-l-phenylalnine. The assay was validated with a linear range between 10 and 150 ng mL(-1) (r ≥ 0.99) and a lower limit of quantification of 10 ng mL(-1) , calculated with weighted (1/x(2) ) least squares linear regression. The RSD of intra-day precision was smaller than 3.6% and the inter-day RSD less than 6.5%, while the average recovery was 100.48% with an RSD of accuracy within 2.9%, determined from quality control samples. The HILIC-MS/MS method was fully validated and successfully applied to the in vivo pharmacokinetic study of stable-isotope 1-(13) C-l-methionine in rats. PMID:21287581

  8. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  9. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane

    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.

  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

    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. Structure-based predictions of 13C-NMR chemical shifts for a series of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles derivatives using GA-based MLR method

    Ghavami, Raouf; Sadeghi, Faridoon; Rasouli, Zolikha; Djannati, Farhad

    2012-12-01

    Experimental values for the 13C NMR chemical shifts (ppm, TMS = 0) at 300 K ranging from 96.28 ppm (C4' of indole derivative 17) to 159.93 ppm (C4' of indole derivative 23) relative to deuteride chloroform (CDCl3, 77.0 ppm) or dimethylsulfoxide (DMSO, 39.50 ppm) as internal reference in CDCl3 or DMSO-d6 solutions have been collected from literature for thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indole derivatives containing different substituted groups. An effective quantitative structure-property relationship (QSPR) models were built using hybrid method combining genetic algorithm (GA) based on stepwise selection multiple linear regression (SWS-MLR) as feature-selection tools and correlation models between each carbon atom of indole derivative and calculated descriptors. Each compound was depicted by molecular structural descriptors that encode constitutional, topological, geometrical, electrostatic, and quantum chemical features. The accuracy of all developed models were confirmed using different types of internal and external procedures and various statistical tests. Furthermore, the domain of applicability for each model which indicates the area of reliable predictions was defined.

  12. Examination of the structure in solid state of amino analogs of 4,4‧-[1,5-pentanediylbis(oxy)]bisbenzonitrile by means of X-ray diffraction, 13C CP/MAS NMR, and theoretical calculations

    Maciejewska, Dorota; Wolska, Irena; Żabiński, Jerzy

    2008-05-01

    A single crystal of X-ray diffraction structures is presented for 4,4'-[1,5-(3-oxapentanediylbis(amino))]bisbenzonitrile 2 and 4,4'-[1,5-( N-methyl-3-azapentane-diylbis(oxy))]bisbenzonitrile 3. The molecular structures of these derivatives differ especially in conformations of the central linker: in 2 this linker adopts a trans/ gauche conformation, whereas in 3 - a fully extended conformation. The N atoms in various positions of the aliphatic linker change dramatically the molecular packing mode of both bisnitriles. But in both cases the nitrile groups take part in intermolecular hydrogen bonds: a type of N sbnd H···N in 2 and of C sbnd H···N in 3. Various conformations of both molecules were reflected in 13C CP/MAS NMR spectra in solid state as single and double resonance patterns for 2 and 3, respectively. A preliminary anticancer assay against 60 cell lines of 3 reveals strong growth inhibition of leukemia, melanoma, and renal cancer cells.

  13. NMR studies of oriented molecules

    Sinton, S.W.

    1981-11-01

    Deuterium and proton magnetic resonance are used in experiments on a number of compounds which either form liquid crystal mesophases themselves or are dissolved in a liquid crystal solvent. Proton multiple quantum NMR is used to simplify complicated spectra. The theory of nonselective multiple quantum NMR is briefly reviewed. Benzene dissolved in a liquid crystal are used to demonstrate several outcomes of the theory. Experimental studies include proton and deuterium single quantum (..delta..M = +-1) and proton multiple quantum spectra of several molecules which contain the biphenyl moiety. 4-Cyano-4'-n-pentyl-d/sub 11/-biphenyl (5CB-d/sub 11/) is studied as a pure compound in the nematic phase. The obtained chain order parameters and dipolar couplings agree closely with previous results. Models for the effective symmetry of the biphenyl group in 5CB-d/sub 11/ are tested against the experimental spectra. The dihedral angle, defined by the planes containing the rings of the biphenyl group, is found to be 30 +- 2/sup 0/ for 5DB-d/sub 11/. Experiments are also described for 4,4'-d/sub 2/-biphenyl, 4,4' - dibromo-biphenyl, and unsubstituted biphenyl.

  14. Determination of the 13C contents of organic acids and sugars in fruit juices: an inter-comparison study

    The determination of the repeatability (r) and reproducibility (R) of the (13C/12C) measurement in sugars and organic acids contained in different fruit juices was conducted on an international basis involving 17 laboratories. The mean values of rper thousand (Rper thousand) for acids and sugars are, respectively, equal to 0.58 (1.75) and 0.34 (0.71) and the relatively large values observed for R of acid determinations are related to the preparation step. However, the least significant difference computed for several pairs of natural and spiked juices indicate that the 13C method can be applied for detecting fruit juice adulteration. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  15. Determination of the {sup 13}C contents of organic acids and sugars in fruit juices: an inter-comparison study

    Guillou, C. [JCR-ISPRA, Environment Institute, Food and Drug Analysis and Consumer Protection Unit, TP740, via Fermi 2, 21020 Ispra (Italy); Koziet, J. [Pernod Ricard, 120, av du Marechal Foch, 94015 Creteil cedex (France); Rossmann, A. [Lehrstuhl fuer Allgemeine Chemie und Biochemie, TUM, D-85350 Freising-Weihenstephan (Germany); Martin, G.J. [CEAIS, Site de la Geraudiere, Rue PA Bobierre, BP 72304, 44323 3 Nantes cedex (France)

    1999-05-03

    The determination of the repeatability (r) and reproducibility (R) of the ({sup 13}C/{sup 12}C) measurement in sugars and organic acids contained in different fruit juices was conducted on an international basis involving 17 laboratories. The mean values of rper thousand (Rper thousand) for acids and sugars are, respectively, equal to 0.58 (1.75) and 0.34 (0.71) and the relatively large values observed for R of acid determinations are related to the preparation step. However, the least significant difference computed for several pairs of natural and spiked juices indicate that the {sup 13}C method can be applied for detecting fruit juice adulteration. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Effect of 13C enrichment in the glassing matrix on dynamic nuclear polarization of [1-13C]pyruvate

    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...

  17. Properties of mixtures of cholesterol with phosphatidylcholine or with phosphatidylserine studied by (13)C magic angle spinning nuclear magnetic resonance.

    Epand, Richard M.; Bain, Alex D; Sayer, Brian G; Bach, Diana; Wachtel, Ellen

    2002-01-01

    The behavior of cholesterol is different in mixtures with phosphatidylcholine as compared with phosphatidylserine. In (13)C cross polarization/magic angle spinning nuclear magnetic resonance spectra, resonance peaks of the vinylic carbons of cholesterol are a doublet in samples containing 0.3 or 0.5 mol fraction cholesterol with 1-palmitoyl-2-oleoyl phosphatidylserine (POPS) or in cholesterol monohydrate crystals, but a singlet with mixtures of cholesterol and 1-palmitoyl-2-oleoyl phosphatidy...

  18. 13 C signal attribution of 5-bromine-2(2'-thienyl)thiophene

    This work has carried out a study of C-H coupling constants in oligothiophenes, through 1 H and 13 C NMR spectra analysis. Nuclear magnetic resonance spectroscopy have been used in order to characterize the molecular structure of them. Chemical shifts were also studied and spectral data have been shown and analysed

  19. Application of stable isotopes to the NMR conformational study of peptides and membrane proteins

    The nuclear magnetic resonance spectral analysis of the lipid-peptide complexes generally necessitates isotopic enrichment, specifically or not, of the lipidic or peptidic partner. The isotope labelling depends on the membrane model and the associated NMR techniques: high resolution 1H NMR of peptides or proteins in the presence of per-deuterated phospholipidic micells, high resolution (micells) or ''solid'' type 2H NMR of the lipid partner, ''solid'' type NMR (15N, 13C) of the peptide partner in a bi-layer. Application examples are given: utilization of stable isotopes for NMR study of lipopeptide structure and dynamic, of folding-up and functional linking at the annexines membrane interface, and of phospholipid conformation and dynamics in the lipids-ions-peptides interactions. 3 figs

  20. Synthesis and applications of 13C glycerol

    The authors are currently developing new synthetic routes to the various isotopomers of glycerol. Labeled glycerol is useful for 13C enrichment of biomolecules. However, traditional methods of glycerol synthesis are not easily adapted for isotopic enrichment or have poor overall yields (12-15%). In addition, the use of glycerol for enrichment can be prohibitively expensive and its availability depends on the level of demand. The authors have developed a short de novo synthesis of [U-13C]glycerol from carbon dioxide (∼53% overall yield for four steps) and are currently examining the feasibility of synthesizing site-specific 13C labeled glycerol and dihydroxyacetone (DHA) from methanol and carbon dioxide. The authors have examined the enzymatic conversion of [U-13C]glycerol to glyceraldehyde-3-monophosphate or dihydroxyacetone monophosphate (DHAP) with yields ranging from 25-50% (as determined by NMR spectroscopy). The authors are also pursuing the chemical conversion of 13C labeled DHA to DHAP and the results are presented. Labeled DHAP is a possible enzymatic precursor for both labeled 2-deoxyribose and 2-deoxyribonucleic acids

  1. Optimized labeling of 13CHD2 methyl isotopomers in perdeuterated proteins: Potential advantages for 13C relaxation studies of methyl dynamics of larger proteins

    13CHD2 methyl isotopomers are particularly useful to study methyl dynamics in proteins because, as compared with other methyl isotopomers, the 13C relaxation mechanism for this isotopomer is straightforward. However, in the case of proteins, where (ωτ)2 >> 1, the refocused INEPT pulse sequence does not completely suppress unwanted 13CH3 signals. The presence of weak 13CH3 peaks is usually not a serious problem for smaller proteins because there are relatively few methyl signals and they are sharp; however, signal overlap becomes more common as the size of the protein increases. We overcome this problem by preparing a protein using a 98% D2O cell culture medium containing 3-13C pyruvic acid, 50-60% deuterated at the 3-position, and 4-13C 2-ketobutyric acid, 98% and 62% deuterated at the 3- and 4-positions, respectively. This approach significantly reduces the population of the CH3 isotopomer while optimizing the production of 13CHD2, the isotopomer desired for 13C relaxation measurements. In larger proteins where the deuterium T2 may be too short to measure accurately, we also suggest the alternative measurement of the proton T2 of the 13CH2D methyl isotopomer, because these protons are well-isolated from other protons in these highly deuterated samples

  2. Study of ketone body kinetics in children by a combined perfusion of /sup 13/C and /sup 2/H3 tracers

    Bougneres, P.F.; Ferre, P.

    1987-11-01

    Ketone body kinetics were quantified in six children (3-5 yr old), who were fasted for 13-22 h, by a combined perfusion of (3-/sup 13/C)acetoacetate ((/sup 13/C)AcAc) and D-(-)-beta-(4,4,4-/sup 2/H3)hydroxybutyrate (beta-(/sup 2/H3)OHB) and gas chromatography-mass spectrometry analysis. Results were analyzed according to the single-pool (combined enrichments) or the two-accessible pools models. After 20-22 h of fasting, ketone body turnover rate was 30-50 mumol.kg-1.min-1, a rate achieved after several days of fasting in adults. At low ketosis, acetoacetate was the ketone body preferentially synthesized de novo and utilized irreversibly. When ketosis increased, acetoacetate irreversible disposal was not enhanced, since it was largely converted into beta-OHB, whereas beta-OHB irreversible disposal was very much increased. The single-pool and two-pool models gave similar ketone body turnover rates when (/sup 13/C)AcAc was the tracer, whereas the use of beta-(/sup 2/H3)OHB gave some more divergent results, especially at low ketosis. These studies demonstrate that ketogenesis is very active in short-term fasted children and that the use of a combined infusion of (/sup 13/C)AcAc and beta-(/sup 2/H3)OHB is a convenient way to give insight into individual ketone body kinetics.

  3. Sampling technique for collection of expired COsub(2) in studies using naturally labelled sup(13)C in calves

    Natural isotopic labelling of animal metabolic processes presents great advantages over the use of artificially enriched compounds. These advantages include the use of natural diets, low cost and easiness of handling, sampling and disposal. Changes in the sup(13)C/sup(12)C ratio of expired COsub(2) after ingestion of a test meal containing a variable proportion of Csub(3) and/or Csub(4) plant-derived products permits measurements of the immediate oxidation of dietary carbohydrates. A breathing device for collection of expired COsub(2) and purification techniques are described. The breath-sampling device is composed of a polypropylene enclosure and a rubber bag. The rubber bag is blown up by the animal and a sample of the expired gas is transferred to a sampling glass holder in which a vacuum had been previously achieved. Sample purification of expired COsub(2) is done by differential freezing

  4. Conformational study of C8 diazocine turn mimics using 3JCH coupling constants with 13C in natural abundance

    The conformations of two diazocine turn mimics, which were later incorporated into GPIIb/IIIa peptide antagonists, were investigated using nuclear magnetic resonance techniques. The two compounds, methyl (2,5-dioxo-3-(S)-(3-ω-tosylguanidino-propyl)-4-methyl-octahydro-1,4-dazocin-1-yl)acetate (1) and methyl (2,5-dioxo-3-(S)-(3-ω-tosyl-guanidino-propyl)-octahydro-1,5-diazocin-1-yl)acetate (2), differ only in their substituent at the diazocine position 4 nitrogen, yet this substitution results in a marked difference in the affinity of the resulting analogs for the GPIIb/IIIa receptor. It was of interest to determine if the difference observed in the antagonistic potency between these analogs was related to constitutional or, perhaps, conformational differences. The backbone conformations of these two molecules can be determined by measuring vicinal coupling constants along the trimethylene portion of the C8 ring backbone and by measuring interproton NOE intensities between the diazocine methine proton and the protons of the trimethylene group. For compound 1, 3JHH values measured from a P.E.COSY spectrum and interproton distances calculated from ROESY buildup curves indicated the presence of a single C8 ring backbone conformation where the trimethylene bridge adopted a staggered conformation and the Hα1 and Hγ1 protons of the trimethylene group were 2.2 A from the methine proton. For compound 2, however, partial overlap of the central Hβ1 and Hβ2 protons made it impossible to measure 3JHH values from the P.E.COSY spectrum. We therefore used a 13C-filtered TOCSY experiment to measure the 3JCH values in both compounds 1 and 2. These heteronuclear vicinal coupling constants measured with 13C in natural abundance in conjunction with measured interproton NOE intensities indicate that these compounds share a common C8 ring backbone conformation

  5. 2D NMR studies of biomolecules

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

  6. {sup 13}C- and {sup 1}H-detection under fast MAS for the study of poorly available proteins: application to sub-milligram quantities of a 7 trans-membrane protein

    Dannatt, Hugh R. W.; Taylor, Garrick F.; Varga, Krisztina; Higman, Victoria A.; Pfeil, Marc-Philipp; Asilmovska, Lubica; Judge, Peter J.; Watts, Anthony, E-mail: anthony.watts@bioch.ox.ac.uk [University of Oxford, Department of Biochemistry (United Kingdom)

    2015-05-15

    We demonstrate that {sup 13}C-detected spectra recorded using fast (60 kHz) magic angle spinning on sub-milligram (<10 μmol) quantities of a protonated 7 trans-membrane helix protein (bacteriorhodopsin) in its native lipid environment are comparable in sensitivity and resolution to those recorded using 15-fold larger sample volumes with conventional solid state NMR methodology. We demonstrate the utility of proton-detected measurements which yield narrow {sup 1}H linewidths under these conditions, and that no structural alterations are observed. We propose that these methods will prove useful to gain structural information on membrane proteins with poor availability, which can be studied in their native lipid environments.

  7. 13C- and 1H-detection under fast MAS for the study of poorly available proteins: application to sub-milligram quantities of a 7 trans-membrane protein

    We demonstrate that 13C-detected spectra recorded using fast (60 kHz) magic angle spinning on sub-milligram (<10 μmol) quantities of a protonated 7 trans-membrane helix protein (bacteriorhodopsin) in its native lipid environment are comparable in sensitivity and resolution to those recorded using 15-fold larger sample volumes with conventional solid state NMR methodology. We demonstrate the utility of proton-detected measurements which yield narrow 1H linewidths under these conditions, and that no structural alterations are observed. We propose that these methods will prove useful to gain structural information on membrane proteins with poor availability, which can be studied in their native lipid environments

  8. NMR study of hydride systems

    The hydrides of thorium (ThH2, Th4H15 and Th4D15) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x))2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th4H15 than in ThH2; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th4H15; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

  9. Internally Stabilized Selenocysteine Derivatives: Syntheses, $^7^7$Se NMR and Biomimetic Studies

    Phadnis, Prasad P; Mugesh, G.

    2005-01-01

    Selenocystine $([Sec]_2)$ and aryl-substituted selenocysteine (Sec) derivatives are synthesized, starting from commercially available amino acid L-serine. These compounds are characterized by a number of analytical techniques such as NMR $(^1H, ^1^3C and ^7^7Se)$ and TOF mass spectroscopy. This study reveals that the introduction of amino/imino substituents capable of interacting with selenium may stabilize the Sec derivatives. This study further suggests that the oxidation-elimination reacti...

  10. Multi-Spectroscopic Analysis of Seed Quality and 13C-Stable-Iotopologue Monitoring in Initial Growth Metabolism of Jatropha curcas L.

    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.

  11. Multi-Spectroscopic Analysis of Seed Quality and 13C-Stable-Iotopologue Monitoring in Initial Growth Metabolism of Jatropha curcas L.

    Komatsu, Takanori; Ohishi, Risa; Shino, Amiu; Akashi, Kinya; Kikuchi, Jun

    2014-01-01

    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. PMID:25401292

  12. Study of deuterium transfer, isotope effects and structural distributions of products of reactions of coals in deuterated tetralin using 2H and 13C FT-n.m.r. and solid-state 13C FT-n.m.r

    Four coals (bituminous, subbituminous, lignite and canneloid) are treated with tetralin-1,1,4,4,-d4 or - 1,1,-d2 or mixtures of tetralin-d4 and tetralin-d0 at 427 deg C in degassed Pyrex vessels for times between 5 and 60 min. Deuterium depletion and scrambling in solvent-derived products are determined for degassed and air-saturated experiments. Deuterium distributions are determined for preasphaltene and asphaltene fraction (A + P) and light oils (LTO) by 2H FT-n.m.r., and solid coals and products are characterized by 13C CP/MAS and 13C FT-n.m.r. Illinois No. 6, PSOC 837 and PSOC 531 coals selectively consume tetralin-d0 over tetralin-d4 and exhibit isotope effects in the scrambling of deuterium from 1- to 2-positions. Intersite deuterium scrambling in recovered tetralin is negligible at 10 min or shorter reaction times, but deuterium depletion from tetralin is significant at all reaction times. Deuterium is detected predominantly at benzylic-type and secondary aliphatic positions and to a lesser extent at aromatic positions of A + P and LTO fractions at reaction times of 5 min. The presence of air significantly enhances both the extent of deuterium scrambling and the rearrangement of tetralin to 1-methylindan at reaction times of 30 to 60 min. (author)

  13. Experimental study of the dominant channels for the Ti isotopes + 13C reactions. Comparisons with the evaporation programs

    In chapter I we recall the foundations of the statistical theory and the validity of the hypotheses in the Hauser-Feshbach formalism. This theory is interpreted in several so called evaporation codes. We describe the Julian program using a method of calculation (Monte Carlo) which enables inexpensive predictions to be made as against the conventional programs, for determining the dominant channels of the reaction. In chapter II we describe the methodology which makes it possible to pass from γ spectra to relative then absolute cross-sections. The possibilities and also the difficulties of this method are analyzed. In chapter III we present a set of experimental results obtained by the methodology described: reactions of the beam of 13C at 36, 46 and 56 MeV on the Ti isotopes (46, 47, 48, 49 and 50) and, in each case, seeking the dominant channels. This set is intended for preparing our future spectroscopy experiments in the fp shell, test the validity of the statistical theory interpreted in the Julian code. In chapter IV we compare the results of the Julian calculation with our experimental results and we had to compare different evaporation codes

  14. Studies of palaeovegetation changes in the Central Amazon by carbon isotopes (12C, 13C, 14C) of soil organic matter

    The paper presents carbon isotope data δ13C and 14C on soil organic matter collected along an ecosystem transect in southern Amazon state, north-central Amazon region, that includes three distinct vegetation communities: savannah (Campos de Humaita), a savannah-forest transition and forest (Manaus). The study sites are located along road BR 319. Botanical identification and 13C analysis of modern vegetation in the savannah and forest sites indicate that most of the vegetation is C3 plants, although a few C4 plants are present at Campos de Humaita. The 13C and 14C data for soil organic matter in the Humaita region show that significant vegetation changes have occurred in the past, probably associated with climatic changes. During the early Holocene, forest vegetation extended throughout the study region, including areas occupied today by savannah vegetation. Savannah vegetation expanded at least 2 km into the modern forest ecotone during the middle Holocene, suggesting drier conditions. The last approximately 1000 years appear to indicate a recent expansion of forest vegetation, reflecting a return to a more moist climate. The study illustrates that the transition area between forest and savannah vegetation is quite sensitive to climatic changes, and this region should be the focus of more extensive research related to past climate and vegetation dynamics in the Amazon region. (author)

  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

    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. The phenomenology of optically pumped (13)C NMR in diamond at 7.05T: Room temperature polarization, orientation dependence, and the effect of defect concentration on polarization dynamics.

    Scott, Eric; Drake, Melanie; Reimer, Jeffrey A

    2016-03-01

    Room temperature optical illumination of NV- imbibed single crystal diamonds with a 532nm laser produces (13)C polarization enhancements up to 200 times greater than that of the thermal equilibrium value at 7.05T. We report high field NV- mediated (13)C polarization as a function of the number and type (NV- and P1) of defects in commercially available diamonds. Surprisingly, both positive and negative (13)C 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. PMID:26920840

  17. GLOBAL MOLECULAR ANALYSES OF METHANE METABOLISM IN METHANOTROPHIC ALPHAPROTEOBACTERIUM, METHYLOSINUS TRICHOSPORIUM OB3B.PART II. METABOLOMICS AND 13C-LABELING STUDY

    Marina G. Kalyuzhanaya

    2013-04-01

    Full Text Available In this work we use metabolomics and 13C-labeling data to refine central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotrophic bacterium. We demonstrate here that similar to non-methane utilizing methylotrophic alphaproteobacteria the core metabolism of the microbe is represented by several tightly connected metabolic cycles, such as the serine pathway, the ethylmalonyl-CoA (EMC pathway, and the citric acid (TCA cycle. Both in silico estimations and stable isotope labeling experiments combined with single cell (NanoSIMS and bulk biomass analyses indicate that a significantly larger portion of the cell carbon (over 60% is derived from CO2 in this methanotroph. Our 13C-labeling studies revealed an unusual topology of the assimilatory network in which phosph(enolpyruvate/pyruvate interconversions are key metabolic switches. A set of additional pathways for carbon fixation are identified and discussed.

  18. Carbon-13 NMR spectroscopy of biological systems

    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...

  19. A solid state NMR study of Layered double hydroxides intercalated with para-amino salicylate, A tuberculosis drug

    Jensen, Nicholai Daugaard; Bjerring, Morten; Nielsen, Ulla Gro

    2016-01-01

    Para-amino salicylate (PAS), a tubercolosis drug, was intercalated in three different layered double hydroxides (MgAl, ZnAl, and CaAl-LDH) and the samples were studied by multi-nuclear (1H, 13C, and 27Al) solid state NMR (SSNMR) spectroscopy in combination with powder X-ray diffraction (PXRD...

  20. LAMPF polarized 13C targets

    Ethylene glycol, 1-butanol, and toluene highly enriched in 13C have been used at LAMPF to produce dynamically polarized 13C targets for scattering experiments with protons and pions. Preparation of the materials and characteristic properties of these targets are described. 17 refs., 1 fig