Natural Abundance Carbon-13 Research Articles

Non-destructive analysis of the oil composition of soybean seeds by natural abundance carbon-13 nuclear magnetic resonance spectroscopy.

The signals of fatty acids in the form of triglycerides were observed in the 13C NMR spectrum of an intact soybean seed. The major fatty acid component composition of triglycerides in a soybean seed, which includes linoleic acid, oleic acid and palmitic acid, was estimated by subtracting the spectra of authentic fatty acids from the spectrum of the intact soybean seeds. The fatty acid compositions of seeds of 11 Japanese soybean cultivars and 5 lines bred at the Asian Vegetable Research and Development Center (AVRDC) were estimated by this rapid (within lhr for one seed) and nondestructive analytical method.

Electron spin echo envelope modulation studies of natural abundance carbon-13 and aluminum-27 in two disordered systems

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron spin echo envelope modulation studies of natural abundance carbon-13 and aluminum-27 in two disordered systemsPenny A. Snetsinger, Jeffrey B. Cornelius, R. B. Clarkson, M. K. Bowman, and R. L. BelfordCite this: J. Phys. Chem. 1988, 92, 13, 3696–3698Publication Date (Print):June 1, 1988Publication History Published online1 May 2002Published inissue 1 June 1988https://doi.org/10.1021/j100324a002RIGHTS & PERMISSIONSArticle Views54Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (388 KB) Get e-Alerts

Structure and dynamics of porcine submaxillary mucin as determined by natural abundance carbon-13 NMR spectroscopy.

Nearly all of the resonances in the 13C NMR spectrum of porcine submaxillary mucin glycoprotein (PSM) have been assigned to the peptide core carbons and to the carbons in the eight different oligosaccharide side chains that arise from the incomplete biosynthesis of the sialylated A blood group pentasaccharide (alpha-GalNAc(1-3) [alpha-Fuc(1-2)]-beta-Gal(1-3) [alpha-NeuNGl(2-6)]- alpha-GalNAc-O-Ser/Thr). By use of these assignments, a nearly complete structural analysis of intact PSM has been performed without resorting to degradative chemical methods. Considerable structural variability in the carbohydrate side chains was observed between mucins obtained from different animals, while no variability was observed between glands in a single animal. The dynamics of the PSM core and carbohydrate side chains were examined by using the carbon-13 nuclear magnetic resonance relaxation times and nuclear Overhauser enhancements of each assigned carbon resonance. The peptide core of PSM exhibits internal segmental flexibility that is virtually identical with that of ovine submaxillary mucin (OSM), whose carbohydrate side chain consists of the alpha-NeuNAc(2-6)alpha-GalNAc disaccharide. The longer oligosaccharide side chains of PSM, therefore, have no significant effect on peptide core mobility compared to the shorter side chains of native OSM or asialo-OSM. Although the dynamics of the shorter carbohydrate side chains shared by both OSM and PSM appear to be identical, the A and H blood group structures in PSM have reduced mobilities, indicating that the glycosidic linkages of the terminal sugars in these determinants are relatively inflexible. These results differ from most reports of glycoprotein dynamics, which typically find the terminal carbohydrate residues to be undergoing rapid internal rotation about their terminal glycosidic bonds. The results reported here are consistent with previous studies on the conformations of the A and H determinants derived from model oligosaccharides and further indicate that the conformations of these determinants are unchanged when covalently bound to the mucin peptide core. In spite of their carbohydrate side-chain heterogeneity, mucins appear to be ideal glycoproteins for the study of O-linked oligosaccharide conformation and dynamics and for the study of the effects of glycosylation on polypeptide conformation and dynamics.

Synthesis and characterisation of [N(PPh3)2][RuRh5(CO)16] by X-ray crystallography and by natural-abundance carbon-13 nuclear magnetic resonance spectroscopy

The synthesis, X-ray crystal structure, and spectroscopic studies of a new ruthenium–rhodium mixed-metal cluster [N (PPh3)2][RuRh5(CO)16] are reported. The complex crystallises in the space group C2/c with a= 33.62(1), b= 9.729(2), c= 33.72(1)A, β= 94.43(2)°, and Z= 8. The crystal structure is isomorphous with [N(PPh3)2][FeRh5(CO)16]. No fluxionality was observed at room temperature by natural-abundance 13C n.m.r. spectroscopy, which established the [Rh6(CO)16]-like structure also in solution.

Nematic and Smectic Ordering of 4-n-Octyl-4′-cyanobiphenyl Studied by Carbon- 13 NMR

Abstract A new NMR method called RHODIUM (Removal of HOmonuclear DIpolar-couplings and the Use of off-Magic-angle-spinning) has been applied to study the molecular ordering of 4-n-octyl-4′-cyanobiphenyl (8CB) as a function of temperature. C-H dipolar coupling constants of various carbon atoms in 8CB were obtained from natural abundance carbon-13 NMR. Order parameters of the benzene rings and those of the C-H bonds in the octyl chain were calculated from the dipolar coupling constants. The order parameter of the -CN axis can also be calculated from the chemical shift of the -CN group. The results are consistent with the second order nature of the smectic A-nematic phase transition in 8CB.

N.m.r. study of conformational changes in lysozyme around the thermal transition point.

Natural abundance carbon-13 n.m.r. at 50.3 MHz has been used to further document the thermal transition that hen egg-white lysozyme undergoes in solution between 20 degrees and 30 degrees. The study focuses on the temperature sensitivity of more than 50 carboxylic, aromatic and aliphatic single carbon resonances for which unambiguous assignments to specific residues are known. The analysis of selective perturbations in chemical shifts indicates that residues located on both edges of the active site cleft and in the hydrophobic box are primarily involved in the temperature-induced conformational transition. N.m.r. results are compared with crystallographic data on low temperature (form A) and high temperature (form B) interconverting lysozyme crystals, taking advantage of the recent availability of quality high resolution maps for B form orthorhombic crystals. In most cases, a good correlation is found at the atomic level between residues involved in the thermal transition in solution and in the crystalline state. Discrete discrepancies are noted for some residues such as Trp-62 and His-15.

Natural abundance carbon-13 nuclear magnetic resonance studies of histone and DNA dynamics in nucleosome cores.

Natural abundance carbon-13 nuclear magnetic resonance spectra (67.9 MHz) were obtained for native nucleosome cores: cores dissociated in 2 M NaCl and 2 M NaCl, 6 M urea; and cores degraded with DNase I plus proteinase K. Phosphorus-31 NMR spectra of native and dissociated cores and core length DNA were also obtained at 60.7 MHz. The 31P resonance and spin-lattice relaxation time (T1) of DNA were only slightly affected by packaging in nucleosome cores, in agreement with other reports, but 13C resonances of DNA were essentially unobservable. The loss of DNA spectral intensity suggests that rapid internal motions of DNA sugar carbons in protein-free DNA previously demonstrated by 13C NMR methods are partly restricted in nucleosomes. The 13C spectrum of native cores contains many narrow intense resonances assigned to lysine side chain and alpha-carbons, glycine alpha-carbons, alanine alpha- and beta- carbons, and arginine side chain carbons. Several weaker resonances were also assigned. The narrow line widths, short T1 values, and non-minimal nuclear Overhauser enhancements of these resonances, including alpha- and beta-carbons, show that some terminal chain segments of histones in nucleosomes are as mobile as small random coil polypeptides. The mobile segments include about 9% of all histone residues and 25% of all lysines, but only 10% of all arginines. The compositions of these segments indicate that mobile regions are located in amino- or carboxyl-terminal sequences of two or more histones. In addition, high mobility was observed for side chain carbons of 45-50% of all lysines (delta and epsilon carbons) and about 25% of all arginines (zeta carbon) in histones (including those in mobile segments), suggesting that basic residues in terminal histone sequences are not strongly involved in nucleosome structure and may instead help stabilize higher order chromatin structure.

1Hand 19F NMR study with carbon-13 satellites of para-difluorobezene in various nematic liquid crystals: structure and J-coupling anisotropy

The proton and fluorine NMR spectra, with natural-abundance carbon-13 satellites, of para-difluorobenzene dissolved in various nematic liquid crystals are analysed. The complete r α-structure was determined in five liquid crystals solvents and found to be practically independent of the solvent. Evidence has been found of an anisotropy in the indirect fluorine—fluorine and in the three- and four-bond fluorine—carbon couplings whereas the anisotropy of the other fluorine—carbon couplings appears negligible. The isotope effects on fluorine chemical shielding due to the replacement of carbon-12 by carbon-13 are also reported. The substituent effects of fluorine in difluorobenzenes are summarized.

Deuteron quadrupole coupling constants of methyl bromide- d3 and bromoform- d determined by 2H NMR in mixtures of nematic liquid crystals

The deuteron quadrupole coupling constants (DQCC) of methyl bromide- d 3 and bromoform- d were studied as a function of the liquid-crystal solvent by using 2H NMR spectroscopy and observing natural-abundance carbon-13 satellites. Furthermore, the solvent dependence of the DCD bond angle in methyl bromide is reported. The variations of these parameters are discussed in terms of the correlation between molecular vibration and reorientational motion. The DQCCs for methyl bromide- d 3 and bromoform- d are predicted to be 177 ± 1 kHz and 184 ± 1 kHz, respectively.

ChemInform Abstract: STABLE CARBOCATIONS. 264. OBSERVATION OF SECONDARY CARBON‐13 EQUILIBRIUM ISOTOPE EFFECT IN THE DEGENERATE REARRANGEMENT OF 2,3‐DIMETHYL‐2‐BUTYL CATION USING NATURAL ABUNDANCE CARBON‐13 NMR SPECTROSCOPY

Chemischer InformationsdienstVolume 16, Issue 49 Preparative Organic Chemistry ChemInform Abstract: STABLE CARBOCATIONS. 264. OBSERVATION OF SECONDARY CARBON-13 EQUILIBRIUM ISOTOPE EFFECT IN THE DEGENERATE REARRANGEMENT OF 2,3-DIMETHYL-2-BUTYL CATION USING NATURAL ABUNDANCE CARBON-13 NMR SPECTROSCOPY V. V. KRISHNAMURTHY, V. V. KRISHNAMURTHYSearch for more papers by this authorG. K. S. PRAKASH, G. K. S. PRAKASHSearch for more papers by this authorP. S. IYER, P. S. IYERSearch for more papers by this authorG. A. OLAH, G. A. OLAHSearch for more papers by this author V. V. KRISHNAMURTHY, V. V. KRISHNAMURTHYSearch for more papers by this authorG. K. S. PRAKASH, G. K. S. PRAKASHSearch for more papers by this authorP. S. IYER, P. S. IYERSearch for more papers by this authorG. A. OLAH, G. A. OLAHSearch for more papers by this author First published: December 10, 1985 https://doi.org/10.1002/chin.198549097Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue49December 10, 1985 RelatedInformation

Effect of halothane on the natural-abundance 13C NMR spectra of excised rat brain.

Halothane increases the intensity of the 30.5- and 129-ppm resonances in 13C nuclear magnetic resonance spectra of excised rat brain, of phospholipid vesicles prepared from chloroform-methanol extract of rat brain, and of brain excised from rats anesthetized with halothane. The 13C spin-lattice relaxation times of the 30.5- and 129-ppm resonances are increased in excised brain, or phospholipid vesicles, upon addition of halothane, and they are also increased in brain excised from rats anesthetized with halothane. Excised brain and its membrane-rich subcellular fractions interact with [14C]halothane reversibly. The interaction is virtually abolished when the phospholipids are extracted from the brain. The [14C]halothane content of the brain membranes is correlated with the halothane-induced increase in the integral of the 129-ppm resonance. From this correlation and from the phospholipid content of the membranes, a halothane concentration of 3.34 mM and a partition of 0.057 mol of halothane/mol of phospholipid may be calculated in the brain of anesthetized rats.

Fusarin C: structure determination by natural abundance carbon-13 - carbon-13 coupling and deuterium-induced carbon-13 shifts

Fusarin C: structure determination by natural abundance carbon-13 - carbon-13 coupling and deuterium-induced carbon-13 shifts

Carbon nuclear magnetic resonance spectra of oligosaccharides isolated from human milk and ovarian cyst mucin

Natural abundance Carbon-13 nuclear magnetic resonance spectra at 20 MHz were reported for the three common human milk oligosaccharides, lacto- N-tetraose and lacto- N-fucopentaoses I and II, as well as for two related tetra- and hexasaccharide alditols isolated from the alkaline borohydride degradation products of an ovarian cyst glycoprotein. Spectral assignments made with the help of deuterium-induced shift (DIS), attached proton test (APT), and T 1 data indicated some very irregular glycosylation shifts which were attributed to effects of steric crowding and non-nearest-neighbor interactions. Samples as small as 10 μmol of oligosaccharide gave acceptable 20-MHz spectra with the use of a 5-mm probe coil.

Carbon-13 and phosphorus-31 NMR study of hepatic metabolism in the perfused rat liver

Phosphorus-31 nuclear magnetic resonance (NMR) has been used to determine non-invasively absolute concentrations of phosphorylated metabolites in the perfused rat liver. It has been shown that the NMR method does detect cytoplasmic ATP and ADP (ATP:ADP ratio of 15 +/- 3) with no contribution from mitochondrial adenine nucleotides. The concentration of ATP was 7.2 +/- 0.3 mM in the cytosol of well-oxygenated liver, after two hours of perfusion with a Krebs-Ringer buffer. Other phosphorylated metabolites were detected, mainly inorganic phosphate (1.1 mumol/g liver wet weight), phosphorylcholine (1.0 mumol/g wet weight), glycerophosphorylethanolamine (0.34 mumol/g wet weight) and glycerophosphorylcholine (0.30 mumol/g wet weight). The intracellular pH measured from the position of the Pi resonance has a value of 7.2 +/- 0.1. It is likely that the detectable Pi originates from the cytosolic compartment since a pH value of 7.4-7.6 would be expected for the mitochondrial matrix. Natural abundance carbon-13 NMR has also been used to follow the glycogen breakdown in situ by measuring the intensity of the glycogen C-1 resonance in the perfused liver spectrum as a function of the perfusion time. The glycogenolytic process has been studied as a function of the glucose content of the perfusate. Rate of glycogenolysis from 2.7 to 0.16 muEq glycosyl units g wet weight-1 min-1 were found when glucose concentration in the perfusate was varied from 0 to 50 mM. The fate of 90% enriched [2-13C] acetate has been studied in the perfused rat liver by 13C-NMR in order to investigate the mitochondrial metabolism and the interrelations between cytosolic and mitochondrial pools of metabolites. Some compounds of the intermediary metabolism where found to be extensively labelled, e.g. glutamate, glutamine, acetoacetate and beta-hydroxybutyrate. Under our experimental conditions, labelling of glutamate reached a steady-state within 30 min after the onset of perfusion of 20 mM acetate. In addition, the observed incorporation of carbon-13 isotope into glutamine can be linked to the operation of the glutamate-glutamine antiporter and to the high activity of the cytosolic glutamate synthetase. The finding of both active glutaminase and glutamine synthetase activity in the same liver cells is an evidence of the existence of an active glutamine-glutamate futile cycle.

Backbone and side-chain motion in myosin, subfragment 1, and rod determined by natural abundance carbon-13 NMR.

We report natural abundance carbon-13 nuclear magnetic resonance studies of myosin, subfragment 1 (S-1), and myosin rod in solution and of myosin filaments. We measured solution spectra at 37.7 MHz, 20 degrees C with scalar proton decoupling. If the native proteins were rigid particles, only S-1 would have observable intensity. In fact, 30% of myosin, 70% of S-1, and 30% of rod carbons are observable. Observable carbons possess rotational correlation times less than 10(-7) s which effectively average 13C-1H dipolar coupling and anisotropic chemical shift interactions. Short alpha-carbon region spin-lattice relaxation times (T1) and nonminimal 13C-1H nuclear Overhauser enhancements suggest restricted nanosecond motions of backbone atoms. This is direct evidence for internal motion of backbone and side-chain carbons in myosin and its fragments. Double resonance experiments at 15.1 MHz and 5 degrees C with pelleted myosin filaments detected carbon atoms in rigid domains. While most (80%) aliphatic carbons are strongly 13C-1H dipolar coupled due to limited motion, they have short T1 values and large nuclear Overhauser enhancement values; this is evidence for high frequency restricted motion. Cross-polarization experiments show that the 13C carbonyl line width is motionally narrowed, suggesting broad backbone motions in the 100 mus range. Thus, motion in filaments is highly anisotropic.

In vivo detection of cryoprotectants and lipids in overwintering larvae using carbon-13 nuclear magnetic resonance spectroscopy

Natural abundance carbon-13 nuclear magnetic resonance (NMR) spectra of intact, acclimated Eurosta solidaginis larvae have been obtained. The spectra show peaks assignable to lipid components and the presence of one major type of monounsaturated fatty acid. Chloroform-soluble extracts of whole larvae support this. The major nonlipid carbon components were the two cryoprotectant polyols glycerol and sorbitol. Carbon-13 NMR is a useful tool for analysis of cryoprotectant molecules in whole, living cold acclimated freezing tolerant insects.

Revised guidance on acceptable limits of exposure during nuclear magnetic resonance clinical imaging.

Revised guidance on acceptable limits of exposure during nuclear magnetic resonance clinical imaging.

Structure of teucroxide. Application of natural-abundance carbon-13 - carbon-13 coupling constants observed via double-quantum coherence

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of teucroxide. Application of natural-abundance carbon-13 - carbon-13 coupling constants observed via double-quantum coherenceMaria C. Garcia-Alvarez, Gabor Lukacs, Andras Neszmelyi, Franco Piozzi, Benjamin Rodriguez, and Guiseppe SavonaCite this: J. Org. Chem. 1983, 48, 25, 5123–5126Publication Date (Print):December 1, 1983Publication History Published online1 May 2002Published inissue 1 December 1983https://doi.org/10.1021/jo00173a068RIGHTS & PERMISSIONSArticle Views64Altmetric-Citations26LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (529 KB) Get e-Alerts Get e-Alerts

Natural abundance Carbon-13 nuclear magnetic resonance spectroscopy of liver and adipose tissue of the living rat.

We have employed the topical magnetic resonance (TMR) technique to obtain natural abundance 13C nuclear magnetic resonance (NMR) spectra from liver and adipose tissue in the living rat. Experiments were performed in a TMR magnet (20-cm diameter) with a two-turn radio-frequency coil ("surface" coil) combined with a focused static magnetic field. The in vivo spectra that were obtained at 20.2 MHz have been assigned by comparison with those from excised organs obtained in a conventional spectrometer operating at 90.5 MHz. Signals in the TMR spectra corresponding to carbons of the carbohydrates, glucose and glycogen, and of the lipids, triglycerides and phospholipids, have been resolved in vivo and assigned. The effects of chronic modification of dietary fat and carbohydrate on the in vivo spectra have been investigated. The levels of carbohydrates and of saturated and unsaturated fats in the liver as measured by 13C TMR reflect the relative amounts of these compounds in the long-term diet.

1H and 19F NMR study of meta-difluorobenzene: Structure, J-coupling anisotropy, and orientational behavior

The proton and fluorine magnetic resonance spectra with natural abundance carbon-13 satellites of meta-difluorobenzene dissolved in nematic liquid crystals were analyzed. The complete r α structure was determined. The structure deviates clearly from hexagonal. Evidence has been found of an anisotropy in the indirect fluorine-fluorine and fluorine-carbon-13 couplings. From the analyses of the 19F and 19F 13C satellite spectra the 13C( 12C) isotope effects on the 19F chemical shift were calculated. The orientational behavior of meta-difluorobenzene was compared with that predicted by theoretical models based on dispersion and repulsion interactions. The data obtained from ZLI 1167 and ZLI 1132 liquid crystals are in agreement with the theory based on dispersion forces, but in other solvents specific interactions also seem to be of importance.