TY - JOUR. T1 - Method of determining protein conformations by the two-dimensional nuclear overhauser enhancement spectroscopy data. AU - Sherman, S. A.. AU - Andrianov, A. M.. AU - Akhrem, A. A.. PY - 1987/4. Y1 - 1987/4. N2 - A method is suggested to determine the most probable values of the angles, y of the protein backbone by the data on the availability and absence of d connectivities in the two-dimensional nuclear Overhauser enhancement spectra. In view of this, the dependences of the protonproton distances in dipeptide units of L-amino acid residues on the dihedral angles tp, y, x, are considered and the conformational states of amino acid residues of the proteins with the known spatial structure are analysed statistically. The potentialities of the method are assessed with the aid of model spectral nuclear magnetic resonance (NMR) parameters obtained from the X-ray data for the bovine pancreatic trypsin inhibitor and avian pancreatic polypeptide. It is shown that the developed procedure ...
TY - JOUR. T1 - Proton nuclear magnetic resonance assignments and secondary structure determination of the Co1E1 rop (rom) protein. AU - Eberle, W.. AU - Klaus, W.. AU - Cesareni, G.. AU - Sander, C.. AU - Rosch, P.. PY - 1990. Y1 - 1990. N2 - The complete resonance assignment of the Co1E1 rop (rom) protein at pH 2.3 was obtained by two-dimensional (2D) proton nuclear magnetic resonance spectroscopy (1H NMR) at 500 and 600 MHz using through-bond and through-space connectivities. Sequential assignments and elements of regular secondary structure were deduced by analysis of nuclear Overhauser enhancement spectroscopy (NOESY) experiments and 3J(HNα) coupling constants. One 7.2-kDa monomer of the homodimer consists of two antiparallel helices connected by a hairpin loop at residue 31. The C-terminal peptide consisting of amino acids 59-63 shows no stable conformation. The dimer forms a four-helix bundle with opposite polarization of neighboring elements in agreement with the X-ray structure.. AB - ...
Fingerprint Dive into the research topics of Intratumoral Agreement of High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopic Profiles in the Metabolic Characterization of Breast Cancer. Together they form a unique fingerprint. ...
TY - JOUR. T1 - Carbon-13 Nuclear Magnetic Resonance Investigations of Phase Transitions and Phase Equilibria in Pure and Mixed Phospholipid Bilayers. AU - Wittebort, R. J.. AU - Blume, A.. AU - Huang, T. H.. AU - Das Gupta, S. K.. AU - Griffin, R. G.. PY - 1982/7. Y1 - 1982/7. N2 - The temperature dependence of the 13C NMR spectra of dipalmitoylphosphatidylethanolamine (DPPE) and three lecithins-dimyristoyl-, dipalmitoyl-, and distearoylphosphatidylcholine- which have been 13C-labeled at the sn-2 carbonyl has been studied. In the Lg or Lp phase, an axially symmetric powder pattern of about 100-ppm breadth is observed, and this transforms to an isotropic line at the main Lβ (Lβ) →Lα phase transition. In the case of DPPE, this transformation occurs precipitously and, with data from 2H spectra of 2H chain labeled DPPE, is shown to be due to a change in conformation at the sn-2 carbonyl. In contrast, the 13C=0 sn-2 spectra of lecithins exhibit a gradual transformation, beginning at ...
A method for determining properties of a mixture of fluids includes: (a) acquiring a plurality of nuclear magnetic resonance measurements from the mixture of fluids, each of the plurality of nuclear magnetic resonance measurements having a different value in an acquisition parameter for which at least one relaxation selected from the group consisting of longitudinal relaxation and transverse relaxation affects magnitudes of the nuclear magnetic resonance measurements; (b) generating a model of the mixture of fluids; (c) calculating a synthesized nuclear magnetic data set based on the model; (d) comparing the synthesized nuclear magnetic data set with the nuclear magnetic resonance measurements; and (e) adjusting the model and repeating (c) and (d), if difference between the synthesized nuclear magnetic data set and the nuclear magnetic measurements is greater than a minimum.
TY - JOUR. T1 - Photochemistry of cytosine derivatives. 2. Photohydration of cytosine derivatives. proton magnetic resonance study on the chemical structure and property of photohydrates. AU - Liu, Fu-Tong. PY - 1978. Y1 - 1978. N2 - Photohydrates of cytidine and cytidylic acids have been definitively characterized to be isomeric 6-hydroxy-5,6-dihydrocytosine derivatives. It has also been demonstrated by nuclear magnetic resonance spectroscopy that (1) the stereochemistry of photohydration is random, (2) the C5-H trans to the C6-OH undergoes a rapid selective exchange in the presence of proton acids, and (3) the dehydration of photohydrates is a trans-elimination. The mechanism of these processes is discussed.. AB - Photohydrates of cytidine and cytidylic acids have been definitively characterized to be isomeric 6-hydroxy-5,6-dihydrocytosine derivatives. It has also been demonstrated by nuclear magnetic resonance spectroscopy that (1) the stereochemistry of photohydration is random, (2) the C5-H ...
TY - JOUR. T1 - Nuclear magnetic relaxation dispersion studies of water‐soluble gadolinium(iii)‐texaphyrin complexes. AU - Geraldes, C. F.. AU - Sherry, A. D.. AU - Vallet, P.. AU - Maton, F.. AU - Muller, R. N.. AU - Mody, T. D.. AU - Hemmi, G.. AU - Sessler, J. L.. N1 - Copyright: Copyright 2016 Elsevier B.V., All rights reserved.. PY - 1995. Y1 - 1995. N2 - Water proton 1/T1 nuclear magnetic relaxation dispersion (NMRD) profiles were measured for a water‐soluble gadolinium(III) texaphyrin (Gd‐tex) complex as a function of temperature and in the presence and absence of 5% human serum albumin (HSA). Upon dissolving the complex in water (0.259 mM), the water relaxivity values decreased with time but remained higher than those of free Gd3+aqat all fields. Concurrent measurements of free Gd3+ using metallochromic dyes indicated that demetallation of the texaphyrin did not occur over a period of several days at 37°C. The high relaxivity values and shape of the NMRD profile of this complex ...
Natural and semi-synthetic compounds are being studied as novel phosphodiesterase 5 (PDE5) inhibitors for the treatment of erectile dysfunction, pulmonary hypertension, and lower urinary symptoms. Maclura pomifera is a source of flavonoids, one of the main classes of molecules investigated for these purposes. The extraction of the natural isoflavone osajin and its modification to obtain a semi-synthetic derivative are described in this short note. 1H and 13C-nuclear magnetic resonance spectroscopy (NMR), mass spectrometry, high-performance liquid chromatography (HPLC) and spectroscopic characterization of the title compound are also hereby provided. Two-dimensional (2D) nuclear Overhauser effect spectroscopy (NOESY) NMR, supported by in silico conformational studies, was used to achieve a complete assignment of the proton signals, assessing the correct chemical structure of the compound. Heteronuclear single quantum coherence spectroscopy (HSQC) and heteronuclear multiple bond correlation (HMBC) NMR
Magic Angle Spinning Nuclear Magnetic Resonance Characterization of Voltage-Dependent Anion Channel Gating in Two-Dimensional Lipid Crystalline Bilayers ...
TY - JOUR. T1 - High-precision measurement of hydrogen bond lengths in proteins by nuclear magnetic resonance methods. AU - Harris, Thomas K.. AU - Mildvan, Albert S.. PY - 1999/5/15. Y1 - 1999/5/15. N2 - We have compared hydrogen bond lengths on enzymes derived with high precision (≤ ±0.05 Å) from both the proton chemical shifts (δ) and the fractionation factors (φ) of the proton involved with those obtained from protein X-ray crystallography. Hydrogen bond distances derived from proton chemical shifts were obtained from a correlation of 59 O-H ···· O hydrogen bond lengths, measured by small molecule high-resolution X-ray crystallography, with chemical shifts determined by solid-state nuclear magnetic resonance (NMR) in the same crystals (McDermott A, Ridenour CF, Encyclopedia of NMR, Sussex, U.K.: Wiley, 1996:3820-3825). Hydrogen bond distances were independently obtained from fractionation factors that yield distances between the two proton wells in quartic double minimum potential ...
COSTA, Flávia Martins et al. Proton magnetic resonance spectroscopy and perfusion magnetic resonance imaging in the evaluation of musculoskeletal tumors. Radiol Bras [online]. 2009, vol.42, n.4, pp.215-223. ISSN 1678-7099. https://doi.org/10.1590/S0100-39842009000400006.. OBJECTIVE: To assess the role of proton magnetic resonance spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in the differentiation between malignant and benign musculoskeletal tumors. MATERIALS AND METHODS: Fifty-five patients with musculoskeletal tumors (27 malignant and 28 benign) were studied. The examinations were performed in a 1.5 T magnetic resonance scanner with standard protocol, and single voxel proton magnetic resonance spectroscopy with 135 msec echo time. The dynamic contrast study was performed using T1-weighted gradient-echo sequence after intravenous gadolinium injection. Timesignal intensity curves and slope values were calculated. The statistical analysis was performed with the Levenes ...
A method for determining a pore characteristic of a substance includes the following steps: subjecting the substance to a substantially uniform static magnetic field; applying a magnetic pulse sequence to the substance, the pulse sequence being selected to produce nuclear magnetic resonance signals that are responsive to internal magnetic field inhomogeneities in the pore structure of the substance, and detecting, as measurement signals, nuclear magnetic resonance signals from the substance; applying a reference magnetic pulse sequence to the substance, the reference pulse sequence being selected to produce nuclear magnetic resonance signals that are substantially unresponsive to internal magnetic field inhomogeneities in the pore structure of the substance, and detecting, as reference measurement signals, nuclear magnetic resonance signals from the substance; and determining a pore characteristic of the substance from the measurement signals and the reference measurement signals.
TY - JOUR. T1 - Proton overhauser enhancements in human cardiac phosphorus NMR spectroscopy at 1.5 T. AU - Bottomley, Aul A.. AU - Hardy, Christopher J.. PY - 1992/4. Y1 - 1992/4. N2 - Narrowband irradiation of water protons with a surface coil yields significant nuclear Overhauser enhancement (nOe) of phosphocreatine (PCr) and some adenosine triphosphate (ATP) moieties in localized and unlocalized phosphorus (31P) NMR spectra from chest and heart muscle. In seven normal subjects at 1.5 T the nOe values were 0.6 ± 0.3, 0.6 ± 0.3, 0 ± 0.3, and 0.3 ± 0.2 for myocardial PCr, γ‐ATP, α‐ATP, and β‐ATP, respectively, not significantly different from those in chest muscle. Distortion of the measured PCr/ATP ratios due to differences in the nOe may require accurate correction to realize the full benefit of the effect in studies involving quantitative intergroup comparisons. © 1992 Academic Press, Inc.. AB - Narrowband irradiation of water protons with a surface coil yields significant ...
TY - JOUR. T1 - 31P nuclear magnetic resonance study of the proton-irradiated KTiOPO4 AU - Kim, Se Hun. AU - Lee, Cheol Eui. PY - 2013/10/17. Y1 - 2013/10/17. N2 - 31P nuclear magnetic resonance (NMR) was employed to study the effects of proton irradiation on KTiOPO4 (KTP) in view of the previously studied paramagnetic impurity doping effects. High-resolution 31P NMR measurements showed significant increase in the isotropic chemical shifts of the two inequivalent phosphorus sites in the proton-irradiated KTP system, indicating decrease in the electron density around the phosphorous nuclei. The 31P NMR linewidths of the KTP system manifested anomalies associated with the superionic transition and with the polaron formation, which became much weaker after proton irradiation. Besides, the activation energy of the charge carriers increased significantly after proton irradiation.. AB - 31P nuclear magnetic resonance (NMR) was employed to study the effects of proton irradiation on KTiOPO4 (KTP) in ...
High-resolution magic angle spinning proton (HRMAS 1H) magnetic resonance spectroscopy produces well-resolved spectra of metabolites from intact tissue specimens. Here we report the results of a preliminary study of 19 human brain tumors obtained by applying this method. Among these 19 cases were 2 low-grade astrocytomas, 1 anaplastic astrocytoma, 8 glioblastomas, 6 meningiomas, and 2 schwannomas. In addition, autopsy human brain tissues from two subjects without any known neurological diseases were used as normal controls. The HRMAS 1H magnetic resonance spectroscopy measurements were performed at 2°C on a 400-MHz NMR spectrometer with a HRMAS speed of 2.5 kHz. From these HRMAS 1H MR spectra, we measured the concentrations of 11 metabolites, the ratios of 15 metabolites (resonances) to creatine (at 3.03 ppm), and the spin-spin relaxation time for these metabolites (resonances). Our results indicate that these parameters have the potential to characterize tumor types and grades with statistical ...
TY - JOUR. T1 - Studies by 1H nuclear magnetic resonance and distance geometry of the solution conformation of the α-amylase inhibitor Tendamistat. AU - Kline, Allen D.. AU - Braun, Werner. AU - Wüthrich, Kurt. PY - 1986/5/20. Y1 - 1986/5/20. N2 - This is a preliminary report on the determination of the solution conformation of the α-amylase inhibitor Tendamistat by nuclear magnetic resonance and distance geometry calculations. A characterization is given of the complete polypeptide backbone fold and the side-chains of the presumed active site in this protein. These results are based on complete sequence-specific resonance assignments, a list of 401 distance constraints from nuclear Overhauser effects, 168 distance constraints from hydrogen bonds and disulphide bridges, and 50 torsion angle constraints from measurements of spin-spin coupling constants.. AB - This is a preliminary report on the determination of the solution conformation of the α-amylase inhibitor Tendamistat by nuclear ...
Solid state nuclear magnetic resonance studies of hydroxypropylmethylcellulose acetyl succinate polymer, a useful carrier in pharmaceutical solid dispersions. (deposited 07 Jan 2020 15:02) [Currently Displayed] ...
The Kingston Upon Hull Centre for Magnetic Resonance Investigations (CMRI), which opened in 1992, is a magnetic resonance imaging centre located in the city of Kingston upon Hull (Hull) in the East Riding of Yorkshire, England, UK. It is situated in the grounds of the Hull Royal Infirmary hospital in the centre of the city. The centre carries out both cancer research studies, under the auspices of the University of Hull, and clinical scanning, under the auspices of the local NHS trust, Hull and East Yorkshire Hospitals. The centre currently has three MRI scanners; two 1.5 tesla scanners owned by the NHS (a Philips Intera and a GE Signa) and a 3.0 tesla MR 750 GE Signa scanner owned by the University which was installed in January 2009 (one of the first 3.0 tesla whole-body capable systems in Europe). The medical research is carried out under the Directorship of Professor Lindsay W. Turnbull, and is devoted to the application of magnetic resonance imaging and magnetic resonance spectroscopy ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Preface XV. 1 Introduction 1. 1.1 Literature 8. 1.2 Units and Constants 9. References 10. Part I Basic Principles and Applications 11. 2 The Physical Basis of the Nuclear Magnetic Resonance Experiment.. Part I 13. 2.1 The Quantum Mechanical Model for the Isolated Proton 13. 2.2 Classical Description of the NMR Experiment 16. 2.3 Experimental Verification of Quantized Angular Momentum and of the Resonance Equation 17. 2.4 The NMR Experiment on Compact Matter and the Principle of the NMR Spectrometer 19. 2.4.1 How to Measure an NMR Spectrum 19. 2.5 Magnetic Properties of Nuclei beyond the Proton 25. References 27. 3 The Proton Magnetic Resonance Spectra of Organic Molecules - Chemical Shift and Spin-Spin Coupling 29. 3.1 The Chemical Shift 29. 3.1.1 Chemical Shift Measurements 32. 3.1.2 Integration of the Spectrum 35. 3.1.3 Structural Dependence of the Resonance Frequency - A General Survey 37. 3.2 Spin-Spin Coupling 41. 3.2.1 Simple Rules for the Interpretation of Multiplet Structures 46. 3.2.2 ...
1. One- and two-dimensional (correlated shift spectroscopy) high resolution proton n.m.r. spectra of human cerebrospinal fluid (CSF) are reported. The merits of water suppression by freeze drying or irradiation, and spectral simplification by spin-echo methods, are discussed. 2. Well-resolved resonances for a range of low molecular weight metabolites such as lactate, 3-d-hydroxybutyrate, alanine, acetate, citrate, glucose, valine and formate were observed. Resonances for glutamine were observed only from freeze dried samples. Concentrations determined by n.m.r. were in reasonable agreement with those from conventional methods. 3. The n.m.r. spectra of CSF were related to the clinical conditions of the subjects. No resonances for citrate were present in spectra of CSF from subjects (three infants) with bacterial meningitis; high lactate and lowered glucose levels were observed. Strong resonances for glucose and glycine were observed for mildly diabetic subjects. Both the aromatic and the ...
1. 31P n.m.r. spectroscopy was used to measure the dissociation constant of MgATP under simulated intracellular conditions and to measure erythrocyte free magnesium concentration.. 2. In a group of 40 subjects, the relationship between erythrocyte free magnesium and blood pressure, age and sex was examined by univariate and multivariate regression analysis.. 3. A weak positive association was found between erythrocyte free magnesium and mean blood pressure. This association was lost in a multivariate regression analysis including both age and sex.. 4. No significant relationship was found between erythrocyte free magnesium and age, sex, family history of hypertension or use of the combined oral contraceptive pill in the sample studied.. ...
Preface XV. 1 Introduction 1. 1.1 Literature 8. 1.2 Units and Constants 9. References 10. Part I Basic Principles and Applications 11. 2 The Physical Basis of the Nuclear Magnetic Resonance Experiment.. Part I 13. 2.1 The Quantum Mechanical Model for the Isolated Proton 13. 2.2 Classical Description of the NMR Experiment 16. 2.3 Experimental Verification of Quantized Angular Momentum and of the Resonance Equation 17. 2.4 The NMR Experiment on Compact Matter and the Principle of the NMR Spectrometer 19. 2.4.1 How to Measure an NMR Spectrum 19. 2.5 Magnetic Properties of Nuclei beyond the Proton 25. References 27. 3 The Proton Magnetic Resonance Spectra of Organic Molecules - Chemical Shift and Spin-Spin Coupling 29. 3.1 The Chemical Shift 29. 3.1.1 Chemical Shift Measurements 32. 3.1.2 Integration of the Spectrum 35. 3.1.3 Structural Dependence of the Resonance Frequency - A General Survey 37. 3.2 Spin-Spin Coupling 41. 3.2.1 Simple Rules for the Interpretation of Multiplet Structures 46. 3.2.2 ...
TY - JOUR. T1 - Proton magnetic resonance spectroscopy and intracranial tumours. T2 - Clinical perspectives. AU - Falini, Andrea. AU - Calabrese, Giovanna. AU - Origgi, Daniela. AU - Lipari, Susanna. AU - Triulzi, Fabio. AU - Losa, Marco. AU - Scotti, Giuseppe. PY - 1996. Y1 - 1996. N2 - Proton magnetic resonance spectroscopy ( 1H-MRS) was applied to characterize intracranial tumours of different hystological types. Seventy patients with intracranial neoplasms were studied before receiving surgery, radiotherapy or chemotherapy. All tumours were characterized by reduced or absent N-acetylaspartate and increased signal from choline-containing compounds. Distinctive patterns were observed only for primitive brain neo-plasms; high-grade gliomas were differentiated from low-grade ones by higher levels of choline-containing compounds. The metabolic aspects of metastatic lesions were similar to high-grade gliomas. These results, together with the limitations of 1H-MRS and future applications are ...
Measurement of myocardial iron is key to the clinical management of patients at risk of iron-overload cardiomyopathy, which is a major killer in transfusion-dependent patients and others with errors of iron metabolism. This applies especially to the large cohort of β-thalassemia major patients, in whom iron accumulation leads to damage in the liver, heart, and endocrine organs. Myocardial iron is assessed clinically with the cardiovascular magnetic resonance relaxation parameter T2*. This study describes the calibration of cardiovascular magnetic resonance relaxation against human iron concentration and the iron distribution throughout the heart under conditions of iron overload. A strong correlation was observed between cardiovascular magnetic resonance relaxation measurements and biochemically derived tissue iron concentration in 12 postmortem human hearts from transfusion-dependent patients, leading to a clinical calibration equation of [Fe]=45.0×(T2*)−1.22, where [Fe] is measured in ...
Law, W.S., Huang, P.Y., Li, S.F.Y., Ong, E.S., Ong, C.N., Sethi, S.K., Saw, S. (2009). Combination of1H nuclear magnetic resonance spectroscopy and liquid chromatography/mass spectrometry with pattern recognition techniques for evaluation of metabolic profile associated with albuminuria. Journal of Proteome Research 8 (4) : 1828-1837. [email protected] Repository. https://doi.org/10.1021/ ...
We aimed to elucidate the effects of caloric and non-caloric sweeteners on liver lipid metabolism in rats using in vivo magnetic resonance spectroscopy (MRS) and to determine their roles in the development of liver steatosis. Wistar rats received normal chow and either normal drinking water, or solutions containing 13% (w/v) glucose, 13% fructose, or 0.4% aspartame. After 7 weeks, in vivo hepatic dietary lipid uptake and de novo lipogenesis were assessed with proton-observed, carbon-13-edited MRS combined with 13C-labeled lipids and 13C-labeled glucose, respectively. The molecular basis of alterations in hepatic liver metabolism was analyzed in detail ex vivo using immunoblotting and targeted quantitative proteomics. Both glucose and fructose feeding increased adiposity, but only fructose induced hepatic lipid accumulation. In vivo MRS showed that this was not caused by increased hepatic uptake of dietary lipids, but could be attributed to an increase in de novo lipogenesis. Stimulation of lipogenesis
PURPOSE: Phosphorus magnetic resonance spectroscopy ((31)P-MRS) affords unique insight into cardiac energetics but has a low intrinsic signal-to-noise ratio (SNR) in humans. Theory predicts an increased (31)P-MRS SNR at 7T, offering exciting possibilities to better investigate cardiac metabolism. We therefore compare the performance of human cardiac (31)P-MRS at 7T to 3T, and measure T1s for (31)P metabolites at 7T. METHODS: Matched (31)P-MRS data were acquired at 3T and 7T, on nine normal volunteers. A novel Look-Locker CSI acquisition and fitting approach was used to measure T1s on six normal volunteers. RESULTS: T1s in the heart at 7T were: phosphocreatine (PCr) 3.05 ± 0.41s, γ-ATP 1.82 ± 0.09s, α-ATP 1.39 ± 0.09s, β-ATP 1.02 ± 0.17s and 2,3-DPG (2,3-diphosphoglycerate) 3.05 ± 0.41s (N = 6). In the field comparison (N = 9), PCr SNR increased 2.8× at 7T relative to 3T, the Cramer-Ráo uncertainty (CRLB) in PCr concentration decreased 2.4×, the mean CRLB in PCr/ATP decreased 2.7× and the PCr
Fluorination of oxide catalysts has been shown to drastically change the catalytic properties of these materials. The catalytic activity of these materials has been studied using a wide variety of reactions. Research on fluorinated oxides has focused upon improving product yields and product selectivity and upon obtaining a better understanding of the unmodified oxide catalyst as changes due to fluorination are observed. The purpose of this investigation has been to demonstarate the utility of pulsed nuclear magnetic resonance (NMR) spectroscopy as a direct spectroscopic probe of the local chemical environment of the hydroxyl groups and the fluorine atoms of these materials ...
Native human mammary MCF-7 adenocarcinoma cells and a subline displaying resistance to 4-hydroperoxycyclophosphamide, the chemically activated form of cyclophosphamide, were grown as multicellular spheroids or on a collagen sponge matrix and perfused for study by 31P and 13C nuclear magnetic resonance spectroscopy. The natural abundance 13C spectrum of the perfused cells exhibits well-resolved resonances due to the intracellular glutathione (GSH). The resistant cell line shows a higher intensity of the GSH 13C resonances, consistent with the increased GSH concentration determined from biochemical assays of extracts. Treatment of the resistant cell line with buthionine sulfoximine selectively diminishes the intensity of the GSH resonances in the 13C nuclear magnetic resonance spectrum.. ...
Neutrophil-activating protein-2 (NAP-2) is a 72 residue protein demonstrating a range of proinflammatory activities. The solution structure of monomeric NAP-2 has been investigated by two-dimensional 1H-n.m.r. spectroscopy. Sequence-specific proton resonance assignments have been made and secondary structural elements have been identified on the basis of nuclear Overhauser data, coupling constants and amide hydrogen/deuteron exchange. The NAP-2 monomer consists of a triple-stranded anti-parallel beta-sheet arranged in a Greek key and a C-terminal helix (residues 59-70) and is very similar to that found in the n.m.r. solution conformation of dimeric interleukin-8 and the crystal structure of tetrameric bovine platelet factor-4. Results are discussed in terms of heparin binding and neutrophil-activation properties of NAP-2. ...
Correlation spectroscopy is one of several types of two-dimensional nuclear magnetic resonance (NMR) spectroscopy. Other types of two-dimensional NMR include J-spectroscopy, exchange spectroscopy (EXSY), and Nuclear Overhauser effect spectroscopy (NOESY.) Two-dimensional NMR spectra provide more information about a molecule than one-dimensional NMR spectra and are especially useful in determining the structure of a molecule, particularly for molecules that are too complicated to work with using one-dimensional NMR. The first two-dimensional experiment, COSY, was proposed by Jean Jeener, a professor at Universit Libre de Bruxelles, in 1971. This experiment was later implemented by Walter P. Aue, Enrico Bartholdi and Richard R. Ernst, who published their work in 19761. A two-dimensional NMR experiment involves a series of one-dimensional experiments. Each experiment consists of a sequence of radio frequency pulses with delay periods in between them. It is the timing, frequencies, and intensities ...
The lactose transport protein (LacS) from Streptococcus thermophilus bearing a single cysteine mutation, K373C, within the putative interhelix loop 10-11 has been overexpressed in native membranes. Cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy (NMR) could selectively distinguish binding of (13)C-labeled substrate to just 50-60 nmol of LacS(K373C) in the native fluid membranes. Nitroxide electron spin-label at the K373C location was essentially immobile on the time scale of both conventional electron spin resonance spectroscopy (ESR) (|10(-8)s) and saturation-transfer ESR (|10(-3)s), under the same conditions as used in the NMR studies. The presence of the nitroxide spin-label effectively obscured the high-resolution NMR signal from bound substrate, even though (13)C-labeled substrate was shown to be within the binding center of the protein. The interhelix loop 10-11 is concluded to be in reasonably close proximity to the substrate binding site(s) of LacS (|15 A), and
Multiscale nuclear magnetic relaxation dispersion of complex liquids in bulk and confinement, Progress in Nuclear magnetic resonance spectroscopy 104, 12-55, (2018). by : J.-P. Korb [email protected] Abstract. The nuclear magnetic relaxation dispersion (NMRD) technique consists of measurement of the magnetic- field dependence of the longitudinal nuclear-spin-lattice relaxation rate 1/T1. Usually, the acquisition of the NMRD profiles is made using a fast field cycling (FFC) NMR technique that varies the magnetic field and explores a very large range of Larmor frequencies (10 kHz < x0/(2p) < 40 MHz). This allows extensive explorations of the fluctuations to which nuclear spin relaxation is sensitive. The FFC technique thus offers opportunities on multiple scales of both time and distance for characterizing the molecular dynam- ics and transport properties of complex liquids in bulk or embedded in confined environments. This review presents the principles, theories and ...
Interpretation Of Proton Nmr Spectra - 28 images - Chemistry Assignment Of 13c Nmr Spectra To Structural, Benchtop Nmr On Ibuprofen Molecules, How To Interpret Proton Nmr Spectra Thespectroscopy, Image Gallery Nmr Spectrum, Organic Spectroscopy International 1h Nmr
Apparatus is provided for coupled liquid chromatography and nuclear magnetic resonance (NMR) spectroscopy measurements. The apparatus includes a liquid chromatograph, an intermediate storage device for intermediately storing of components of a probe eluent and an NMR spectrometer. Selected intermediately stored components are fed to an NMR measurement unit. The intermediate storing device includes a number of capillary tubes, which are switchable by an automatically controlled valve arrangement for selectively receiving and delivering desired eluent components.
TY - JOUR. T1 - Magnetic Resonance Spectroscopy of the Breast. T2 - Current Status. AU - Bolan, Patrick J.. PY - 2013/8/1. Y1 - 2013/8/1. N2 - Invivo magnetic resonance spectroscopy (MRS) of the breast can be used to measure the level of choline-containing compounds, which is a biomarker of malignancy. In the diagnostic setting, MRS can provide high specificity for distinguishing benign from malignant lesions. MRS also can be used as an early response indicator in patients undergoing neoadjuvant chemotherapy. This article describes the acquisition and analysis methods used for measuring total choline levels in the breast using MRS, reviews the findings from clinical studies of diagnosis and treatment response, and discusses problems, limitations, and future developments for this promising clinical technology.. AB - Invivo magnetic resonance spectroscopy (MRS) of the breast can be used to measure the level of choline-containing compounds, which is a biomarker of malignancy. In the diagnostic ...
TY - JOUR. T1 - A study of spin-lattice relaxation rates of glucose, fructose, sucrose and cherries using high-T c SQUID-based NMR in ultralow magnetic fields. AU - Liao, Shu-Hsien. AU - Wu, Pei Che. PY - 2017/7/5. Y1 - 2017/7/5. N2 - We study the concentration dependence of spin-lattice relaxation rates, T 1 -1, of glucose, fructose, sucrose and cherries by using high-T c SQUID-based NMR at magnetic fields of ∼97 μT. The detected NMR signal, Sy (T Bp), is fitted to [1 - exp(-T Bp/T 1)] to derive T 1 -1, where Sy (T Bp) is the strength of the NMR signal, T Bp is the duration of pre-polarization and T 1 -1 is the spin-lattice relaxation rate. It was found that T 1 -1 increases as the sugar concentrations increase. The increased T 1 -1 is due to the presence of more molecules in the surroundings, which increases the spin-lattice interaction and in turn enhances T 1 -1. The T 1 -1versus degrees Brix curve provides a basis for determining unknown Brix values for cherries as well as other ...
Reply to: On the Correction of Effects of Flip Angle in 1H Magnetic Resonance Spectroscopy Signal Acquired Using Stimulated Echo Acquisition Mode ...
Subjects. NMR studies were performed with eight healthy volunteers (four males and four females; aged 29 ± 6; mean ± SD) at rest after a 12 hr overnight fasting. Informed written consent was obtained from all subjects after the aims and potential risks were explained to them. The protocol was approved by the Yale University School of Medicine Human Investigation Committee.. NMR acquisition. NMR data were acquired on a 2.1 T whole body (1 m bore) magnet connected to a modified Bruker AVANCE spectrometer (Bruker Instruments, Billerica, MA). Subjects remained supine in the magnet with the head lying on top of a home-built radio-frequency NMR probe, consisting of one13C circular coil (8.5 cm diameter) and two 1H quadrature coils for1H acquisitions and decoupling. After tuning, acquisition of scout images, shimming with the FASTERMAP procedure (Shen et al., 1997), and calibration of the decoupling power,13C NMR spectra were acquired for 10 min before and during a 160 min [2-13C] acetate infusion ...
Subjects. NMR studies were performed with eight healthy volunteers (four males and four females; aged 29 ± 6; mean ± SD) at rest after a 12 hr overnight fasting. Informed written consent was obtained from all subjects after the aims and potential risks were explained to them. The protocol was approved by the Yale University School of Medicine Human Investigation Committee.. NMR acquisition. NMR data were acquired on a 2.1 T whole body (1 m bore) magnet connected to a modified Bruker AVANCE spectrometer (Bruker Instruments, Billerica, MA). Subjects remained supine in the magnet with the head lying on top of a home-built radio-frequency NMR probe, consisting of one13C circular coil (8.5 cm diameter) and two 1H quadrature coils for1H acquisitions and decoupling. After tuning, acquisition of scout images, shimming with the FASTERMAP procedure (Shen et al., 1997), and calibration of the decoupling power,13C NMR spectra were acquired for 10 min before and during a 160 min [2-13C] acetate infusion ...
Advanced imaging of veterinary cancer patients has evolved in recent years and modalities once limited to human medicine have now been described for diagnostic purposes in veterinary medicine (positron emission tomography/computed tomography, single-photon emission computed tomography, whole body magnetic resonance imaging). Magnetic resonance spectroscopy (MRS) is a non-invasive and non-ionizing technique that is well described in the human medical literature and is most frequently used to evaluate the metabolic activity of tissues with questionable malignant transformation. Differentiation of neoplastic tissue from surrounding normal tissue is dependent on variations in cellular metabolism. Choline (Cho) levels have been described as diagnostic markers for malignancy for many different tumor types in vivo and ex vivo (tissue biopsies). Monitoring of pre- and post-therapy choline metabolites in tumors has also been performed to evaluate a patients response to cancer treatment. Positive ...
Abstract : We have developed new methods enabling in vivo localization and identification of metabolites through their (1)H NMR signatures, in a drosophila. Metabolic profiles in localized regions were obtained using HR-MAS Slice Localized Spectroscopy and Chemical Shift Imaging at high magnetic fields. These methods enabled measurement of metabolite contents in anatomic regions of the fly, demonstrated by a decrease in beta-alanine signals in the thorax of flies showing muscle degeneration.. ...
High resolution magic angle spinning (HRMAS) 1H NMR spectroscopy has been used to resolve different surface and in-pore solvent environments of ethylene carbonate (EC) and dimethyl carbonate (DMC) mixtures absorbed within nanoporous carbon (NPC). Two dimensional (2D) 1H HRMAS NMR exchange measurements revealed that the inhomogeneous broadened in-pore resonances have pore-to-pore exchange rates on the millisecond timescale. Pulsed-field gradient (PFG) NMR diffusometry revealed the in-pore self-diffusion constants for both EC and DMC were reduced by up to a factor of five with respect to the diffusion in the non-absorbed solvent mixtures. ...
Citrate was increased in the majority of gliomas in adult patients. The elevated citrate in our data indicates an altered metabolic state of tumor relative to healthy brain.
Nuclear magnetic resonance spectroscopy of stereoisomers most commonly known as NMR spectroscopy of stereoisomers is a chemical analysis method that uses NMR spectroscopy to determine the absolute configuration of stereoisomers. For example, the cis or trans alkenes, R or S enantiomers, and R,R or R,S diastereomers.[1][2] In a mixture of enantiomers, these methods can help quantify the optical purity by integrating the area under the NMR peak corresponding to each stereoisomer. Accuracy of integration can be improved by inserting a chiral derivatizing agent with a nucleus other than hydrogen or carbon, then reading the heteronuclear NMR spectrum: for example fluorine-19 NMR or phosphorus-31 NMR. Moshers acid contains a -CF3 group, so if the adduct has no other fluorine atoms, the 19F NMR of a racemic mixture shows just two peaks, one for each stereoisomer. As with NMR spectroscopy in general, good resolution requires a high signal-to-noise ratio, clear separation between peaks for each ...
Natural-abundance 13C nuclear magnetic resonance spectra of ten common nucleotides in neutral, aqueous solutions have been determined and interpreted. The spectra of two of these substances were also determined in acidic solutions, and several of the carbon chemical shifts were found to depend markedly on pH. Within the limited range of concentrations employed, there were observed no carbon chemical-shift changes which could be ascribed to base-stacking or base-pairing phenomena. ...
TY - JOUR. T1 - Proton and multinuclear magnetic resonance spectroscopy in the human brain at ultra-high field strength. T2 - A review. AU - Henning, Anke. PY - 2018/3. Y1 - 2018/3. N2 - Magnetic Resonance Spectroscopy (MRS) allows for a non-invasive and non-ionizing determination of in vivo tissue concentrations and metabolic turn-over rates of more than 20 metabolites and compounds in the central nervous system of humans. The aim of this review is to give a comprehensive overview about the advantages, challenges and advances of ultra-high field MRS with regard to methodological development, discoveries and applications from its beginnings around 15 years ago up to the current state. The review is limited to human brain and spinal cord application at field strength of 7T and 9.4T and includes all relevant nuclei (1H, 31P, 13C).. AB - Magnetic Resonance Spectroscopy (MRS) allows for a non-invasive and non-ionizing determination of in vivo tissue concentrations and metabolic turn-over rates of ...
Two new daphnane-type diterpene esters, yuanhuahine (1) and yuanhualine (2), were isolated from the flowers of Daphne genkwa (Thymelaeaceae) along with three known diterpene esters, yuanhuacine (3), yuanhuadine (4), and yuanhuagine (5). Their structures were determined by a combination of 1D and 2D NMR experiments, including correlation spectroscopy (COSY), heteronuclear multiple quantum correlation (HMQC), heteronuclear multiple bond correlation (HMBC), and rotating frame Overhauser enhancement spectroscopy (ROESY) sequences, and mass spectrometry. All the isolated compounds were tested against A549 human lung cancer cells and MRC-5 human normal lung epithelial cells. Compounds 1-5 exhibited potent anti-proliferative effects against A549 lung cancer cells with IC50 values of 12-53 nM, whereas these compounds were relatively non-cytotoxic against MRC-5 normal lung epithelial cells. © 2010 Pharmaceutical Society of Japan ...
In the search for novel chemical scaffolds leading to potential antihypertensive agents, the methanol extract of Murraya paniculata leaves was assessed for its effects on isolated rat aorta rings. The vasorelaxing effect of the chloroform fraction of the methanol plant extract was the most potent for its vasorelaxing activity on rat aorta rings contracted by 60 mM K(+) (K60). Two coumarins were isolated from the chloroform fraction: the novel kimcuongin (1) and the known murracarpin (2). Their structures were determined from spectroscopic evidences including (1)H- and (13)C-NMR, correlation spectroscopy (COSY), nuclear Overhauser effect spectroscopy (NOESY), heteronuclear multiple bond correlation (HMBC), heteronuclear single quantum correlation (HSQC), and high resolution mass spectrometry (HR-MS). Kimcuongin and, to a lesser extent, murracarpin, showed vasorelaxing activity with IC50 values of 37.7 µM and 139.3 µM, respectively. The coumarins kimcuongin and murracarpin may thus represent a ...
Detail záznamu - 1H magnetic resonance spectroscopy study of different histological types of human meningiomas in vitro - Detailné zobrazenie záznamu - Slovenská lekárska knižnica
TY - JOUR. T1 - Metabolic Characterization of Human Non-Hodgkins Lymphomas in Vivo with the Use of Proton-decoupled Phosphorus Magnetic Resonance Spectroscopy. AU - Negendank, William G.. AU - Padavic-Shaller, Kristin A.. AU - Li, Chun Wei. AU - Murphy-Boesch, Joseph. AU - Stoyanova, Radka. AU - Krigel, Robert L.. AU - Schilder, Russell J.. AU - Smith, Mitchell R.. AU - Brown, Truman R.. PY - 1995/8/1. Y1 - 1995/8/1. N2 - Development of biological and clinical uses of in vivo 31P magnetic resonance spectroscopy has been hampered by poor anatomic localization of spectra and poor resolution of overlapping signals within phosphomonoester and phosphodiester regions of the spectrum. We applied 1H decoupling and nuclear Overhauser enhancement to improve resolution of 31P magnetic resonance spectra accurately localized to 21 non-Hodgkins lymphomas (NHL) by using three-dimensional chemical shift imaging. All 21 spectra had large phosphomonoester signals (26% of total phosphorus) that contained high ...
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 external substrates. Citrate-sugar cometabolism was also monitored in dilute cell suspensions for comparison with the nuclear magnetic resonance results. A clear metabolic shift of the end products from glucose metabolism was observed when citrate was provided along with glucose: ethanol was replaced by acetate, and 2,3-butanediol was produced. Reciprocally, the production of lactate and 2,3-butanediol from citrate was increased in the presence of glucose. When citrate was cometabolized with glucose, a 10-fold ...
The chemical structures of isolated compounds were established on the basis of spectroscopical data as Infra-red (IR), 1D (1H, 13C, DEPT 135) and 2D-NMR experiments; Heteronuclear Multiple-Quantum Correlation (HMQC), correlation spectroscopy (COSY) and Heteronuclear Multiple Bond Correlation (HMBC) plus Mass Spectroscopy (MS) data. The 13C NMR data were assigned with the help of HMQC and DEPT 135 experiments while, the connectivitys of the molecular fragments were established by HMBC, COSY and NOESY. The analysis of the spectra and structure elucidation was also facilitated by comparison of observed and published 1H and 13C NMR data for the compounds.. Lysicamine (1): yellow needles (10.21 mg), m.p. 209-211°C, 1H NMR (CDCl3, 600 MHz) δ 7.57 (1H, s, H-3), 8.07 (1H, d, J = 5.2 Hz, H-4), 8.77 (1H, d, J = 5.2 Hz, H-5), 8.48 (1H, dd, J = 9.0, 1.8 Hz, H-8), 7.63 (1H, t, J = 9.0, 1.2 Hz, H-9), 7.86 (1H, t, J = 9.0, 1.4 Hz, H-10), 9.26 (1H, dd, J = 9.0, 1.2 Hz, H-11), 4.13 (3H, s, 1-OCH3), 4.06 (3H, ...
Virulence of Vibrio vulnificus has been strongly associated with encapsulation and an opaque colony morphology. Capsular polysaccharide was purified from a whole-cell, phosphate-buffered saline-extracted preparation of the opaque, virulent phase of V. vulnificus M06-24 (M06-24/O) by dialysis, centrifugation, enzymatic digestion, and phenol-chloroform extraction. Nuclear magnetic resonance spectroscopic analysis of the purified polysaccharide showed that the polymer was composed of a repeating structure with four sugar residues per repeating subunit: three residues of 2-acetamido-2,6-dideoxyhexopyranose in the alpha-gluco configuration (QuiNAc) and an additional residue of 2-acetamido hexouronate in the alpha-galactopyranose configuration (GalNAcA). The complete carbohydrate structure of the polysaccharide was determined by heteronuclear nuclear magnetic resonance spectroscopy and by high-performance anion-exchange chromatography. The 1H and 13C nuclear magnetic resonance spectra were completely ...
High-field proton NMR spectroscopic analysis of urine and plasma has been employed to study the biochemical effects and nephrotoxic action of an intramuscular dose of auranofin in rats. Auranofin induced a characteristic profile of proximal tubular damage as evidenced by aminoaciduria, lactic aciduria and increased urinary acetate concentrations. In addition, ethanol was detectable in both urine and plasma obtained from auranofin-treated rats. Auranofin-mediated elevations in the plasma and urine concentrations of 3-D-hydroxybutyrate indicated an increased utilisation of fats for fuel in rats treated with this novel therapeutic agent.. ...
Group IVA cytosolic phospholipase A2 (cPLA2α) plays an important role in tumorigenesis and angiogenesis. It is overexpressed in basal-like breast cancer (BLBC), which is aggressive and usually triple-negative, making it unresponsive to current targeted therapies. Here, we evaluated the anti-angiogenic effects of a specific cPLA2α inhibitor, AVX235, in a patient-derived triple-negative BLBC model. Mice bearing orthotopic xenografts received i.p. injections of AVX235 or DMSO vehicle daily for 1 week and then every other day for up to 19 days. Six treated and six control mice were terminated after 2 days of treatment, and the tumors excised for high resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS) and prostaglandin E2 (PGE2) enzyme immunoassay (EIA) analysis. A 1-week imaging study was performed on a separate cohort of mice. Longitudinal dynamic contrast enhanced (DCE)-MRI was performed before, after 4 days, and after 1 week of treatment. The mice were then perfused with a
The highly interdisciplinary study of molecular magnetism spans a wide array of topics, ranging from spintronics and quantum computing to enzyme function and MRI contrast agents. At the core of all these fields is the study of materials whose properties can be controlled through the rational design of molecules. The chemical tailoring of molecular magnetic properties can only be achieved by understanding the relationship between the physical and electronic structures. In this dissertation, the interplay between structure and physical properties is probed using a variety of magnetic resonance techniques. In Chapter 1, we give a succinct overview of the various methods utilized in this dissertation. We first describe the experimental methods including electron paramagnetic resonance (EPR), 57Fe nuclear gamma resonance (Mössbauer) spectroscopy, electron double resonance detected nuclear magnetic resonance (ELDOR-NMR), and Fourier transform far-infrared (FTIR) spectroscopy. In addition to the ...
TY - JOUR. T1 - A tridentate CNO-donor palladium(II) complex as efficient catalyst for direct C―H arylation. T2 - Application in preparation of imidazole-based push-pull chromophores. AU - Li, Hui Hong. AU - Maitra, Ratnava. AU - Kuo, Ya Ting. AU - Chen, Jie Hong. AU - Hu, Ching Han. AU - Lee, Hon Man. PY - 2018/1. Y1 - 2018/1. N2 - A series of imidazolium chlorides for the formation of tridentate CNO-donor palladium(II) complexes featuring N-heterocyclic carbene moieties have been developed from cheap and readily available starting materials with high yields. Their palladium complexes were prepared by reactions between the ligand precursors and PdCl2 using K2CO3 as base in pyridine with reasonable yields. These air-stable metal complexes were characterized using 1H NMR and 13C{1H} NMR spectroscopy and elemental analyses. Heteronuclear multiple bond correlation experiments were performed to identify key NMR signals of these compounds. The structures of two of the complexes were also ...
Key words & phrases: isomer of C3H9N (CH3)2CHNH2 Interpreting the C-13 NMR spectra of propan-2-amine (2-aminopropane), C-13 nmr spectrum of propan-2-amine (2-aminopropane), understanding the carbon-13 nmr spectrum of propan-2-amine (2-aminopropane), explaining the line pattern in the high resolution C-13 nmr spectra of propan-2-amine (2-aminopropane), revising the C-13 nmr spectrum of propan-2-amine (2-aminopropane), ppm chemical shifts of the C-13 nmr spectrum of propan-2-amine (2-aminopropane), how to construct the diagram of the C-13 nmr spectrum of propan-2-amine (2-aminopropane), how to analyse the chemical shifts in the carbon-13 NMR spectrum of propan-2-amine (2-aminopropane) deducing the chemical environment of all the carbon atoms in propan-2-amine (2-aminopropane) examining the c13 nmr spectrum of propan-2-amine (2-aminopropane) analysing the 13-c nmr spectrum of propan-2-amine (2-aminopropane) how do you sketch and interpret the C-13 NMR spectrum of propan-2-amine (2-aminopropane) ...
TY - JOUR. T1 - Completing the circuit. T2 - Direct-observe 13C,15N double-quantum spectroscopy permits sequential resonance assignments near a paramagnetic center in acireductone dioxygenase. AU - Pochapsky, Susan Sondej. AU - Sunshine, Joel C.. AU - Pochapsky, Thomas C.. N1 - Copyright: Copyright 2010 Elsevier B.V., All rights reserved.. PY - 2008/2/20. Y1 - 2008/2/20. N2 - Acireductone dioxygenase (ARD) is a 179-residue enzyme containing a paramagnetic Ni+2 ion in the active site. Because of electron-nuclear spin interactions, 1H resonances within ∼9 Å of the Ni+2 are broadened beyond detection. For this reason, 1H-detected multidimensional NMR experiments are not suitable for structural characterization of the active site of ARD, and no isostructural diamagnetic homologue is available. Rapid recycle two-dimensional direct 13C detection NMR methods previously allowed correlation of carbonyl (13C′) carbons with directly bonded 13Cα and 15N spins in ARD (Kostic, M.; Pochapsky, S. S.; ...
Abstract: We present two-dimensional nuclear magnetic resonance spectroscopy protocols based on nitrogen-vacancy (NV) centers in diamond as efficient quantum sensors of protein structure. Continuous microwave driving fields are used to achieve Hartmann-Hahn resonances between NV spin sensor and proximate nuclei for selective control of nuclear spins and measurement of their polarization. Our protocols take advantage of the strong coupling between the NV sensor and the nuclei, thus facilitating coherence control of nuclear spins and relax the requirement of nuclear spin polarization. We dramatically reduce the experimental effort by employing a singular value thresholding matrix completion algorithm from signal processing to regain the resolution of protein structure based on sub-sampled data from NV based single molecule nuclear magnetic resonance spectroscopy. As an illustration, we demonstrate the power of this approach by identifying the nitrogen-Hydrogen interaction peak in an Alanine ...
B. Rajagopalan, W.J. McKenna, M.J. Blackledge, G.K. Radda; Measurement of Phosphorus Metabolism in Hypertrophic Cardiomyopathy by 31P Magnetic Resonance Spectroscopy. Clin Sci (Lond) 1 January 1988; 74 (s18): 9P. doi: https://doi.org/10.1042/cs074009P. Download citation file:. ...
Part I: Procedures and methodology -- Free energy simulations / M. Mezei, D.L. Beveridge -- Computer simulations of macromolecular dynamics : models for vibrational spectroscopy and x-ray refinement / Ronald M. Levy -- Nuclear magnetic resonance relaxation and the dynamics of proteins and membranes : theory and experiment / Attila Szabo -- Molecular dynamics simulation study of polypeptide conformational equilibria : a progress report / Amil Anderson, Mike Carson, Jan Hermans -- Conformational energy calculations on polypeptide and proteins : use of a statistical mechanical procedure for evaluating structure and properties / Harold A. Scheraga, Gregory H. Paine -- Computer simulation of DNA supercoiling / Wilma K. Olson, Janet Cicariello -- Calculation of atomic charges in large molecules / S. Shankar W.J. Mortier, S.K. Ghosh -- A vectorized near-neighbors algorithm of order N for molecular dynamics simulations / S.G. Lambrakos, J.P. Boris, I. Chandrasekhar [and others] -- A comment on ...
Deuterium isotope effects on 13C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQs) The OH proton is deuteriated. The isotope effects on 13C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects are found to be negative, indicating transmission via the hydrogen bond. In addition unusual long-range effects are seen. Structures, NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using DFT methods. Two-bond deuterium isotope effects on 13C chemical shifts are correlated with calculated OH stretching frequencies. Isotope effects on chemical shifts are calculated for systems with OH exchanged by OD. Hydrogen bond potentials are discussed. New and more soluble nitro derivatives are synthesized ...
13C and 1H NMR characterization of the sodium perchlorafe complex of a new tetraoxatetraaza lipophilic cage ligand (1) derived from 1,7-dioxa-4,10-diazacyclododecane has been performed. 1H homonuclear correlated and 1H J-resolved two-dimensional experiments allowed the recognition of resonances due to different types of OCH2CH2N fragments, and of those of the hydrogens of the bridging chains. 13C resonances have been assigned on the basis of a 13C1H heteronuclear correlated two-dimensional experiment, together with the 13C NMR spectra of the synthetic precursors of 1. 13C spin-lattice relaxation times and NOE measurements established that the unique relaxation mechanism is dipole-dipole; the calculated rotational correlation times indicated that molecular reorientation is isotropic. 13C spectra and relaxation times obtained in different solvents showed that specific solute-solvent interactions are absent.. ...
A new polymorphic form of ciprofloxacin saccharinate (CIP-SAC II) is presented, and compared with CIP-SAC I, a different polymorph which we had previously reported. The characterization techniques used were single crystal and powder X-ray diffraction, differential scanning calorimetry, thermogravimetry analysis and infrared and (13)C solid-state nuclear magnetic resonance spectroscopy. The results obtained from these techniques are consistent. Differential scanning calorimetry and thermogravimetric analysis showed that the reaction between the precursors is completed and the crystalline forms of both salts obtained (I and II) are highly pure. Infrared spectroscopy gave clear evidence of a salt formation. Solid-state nuclear magnetic resonance spectroscopy would indicate some degree of qualitative similarity in the intermolecular interaction scheme in both polymorphs, while thermal analysis data might indicate a difference in quantitative terms. A thorough single crystal structure determination ...
Despite the prevalence and impact of mild traumatic brain injury (mTBI), common clinical assessment methods for mTBI have insufficient sensitivity and specificity. Moreover, few researchers have attempted to document underlying changes in physiology as a function of recovery from mTBI. Proton magnet …
Quantitative, in-situ visualisation of metal ion dissolution and transport using 1H magnetic resonance imaging, J. M. Bray, A. J. Davenport, K. S. Ryder, M. M. Britton, Angew. Chem. Int. Ed., 55 (2016) 9394-97. Applications of magnetic resonance imaging to probe chemistry and flow in complex systems, M. M. Britton, Specialist Periodical Reports - Nuclear Magnetic Resonance volume 45 ed. V. Ramesh (2016). Location dependent coordination chemistry and MRI relaxivity, in de novo designed lanthanide coiled coils, M. R. Berwick, L. N. Slope, C. F. Smith, S. M. King, S. L. Newton, R. B. Gillis, G. G. Adams, A. J. Rowe, S. E. Harding, M. M. Britton, A. F. A. Peacock, Chem. Sci., 7 (2016) 2207-16. Probing composition and molecular mobility in thin spherical films using nuclear magnetic resonance measurements of diffusion, A. Vallatos, R. M. Kirsch, R. A. Williams, R. B. Hammond, X. Jia, U. Bröckel and M. M. Britton, Ind. Eng. Chem. Res., 54 (2015) 6825-6830.. Mapping B1-induced eddy current ...
TY - JOUR. T1 - A Nuclear Magnetic Resonance Study of Hydrogen Bonding in Tris(2-N-methylaminoethyl) Borate and Similar Compounds. AU - Meek, Devon W.. AU - Springer, Charles S.. PY - 1966/3. Y1 - 1966/3. N2 - Tris(2-aminoethyl) borate, B(OCH2CH2NH2)3, and the analogous N-methylamino and N,N-dimethylamino compounds have been prepared by the transesterification of methyl borate with the appropriate 2-aminoethanol. The nuclear magnetic resonance spectra show that extensive association of the terminal amino groups occurs in pure tris(N-methylaminoethyl) borate and that this association can be broken apart by heating to 160° or by dissolution in polar organic solvents such as triethylamine or acetonitrile. In order to determine whether the association results from hydrogen bonding or internal B-N coordination, several model systems have been investigated. The spectra of NH2C5H5-BF3, piperidine-BF3, and (C6H5)BO-CH2CH2NH2 in acetonitrile contain very complicated NCH2 peaks and broad NH peaks which ...
TY - JOUR. T1 - Nuclear magnetic resonance spin-lattice relaxation of lithium ions in aqueous solution by NMR and molecular dynamics. AU - Mohammadi, Mohaddese. AU - Benders, Stefan. AU - Jerschow, Alexej. N1 - Funding Information: This work was supported by the National Science Foundation under Award No. CBET 1804723. Publisher Copyright: © 2020 Author(s).. PY - 2020/11/14. Y1 - 2020/11/14. N2 - We study the aqueous solvation dynamics of lithium ions using nuclear magnetic resonance spectroscopy, molecular dynamics, and viscosity measurements. Several relaxation mechanisms are examined to explain the strong increases of spin-lattice relaxation toward high concentrations. The use of both 6Li and 7Li isotopes is helpful to identify the quadrupolar contribution to the relaxation rate. In particular, it is found that the quadrupolar interaction constitutes the strongest contribution above a concentration of ∼10 molal. The next-strongest contribution arises from interactions that scale with the ...
Bark samples isolated from brown coal deposits in Victoria, Australia, and buried wood from Rhizophora mangle have been studies by high-resolution solid-state nuclear magnetic resonance (NMR) techniques. Dipolar dephasing 13C NMR appears to be a useful method of detecting the presence of tannins in geochemical samples including barks, buried woods, peats and leaf litter. It is shown that tannins are selectively preserved in bark during coalification to the brown coal stage. ?? 1988....
The Tm3+ chelate of DOTAM [1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane] possessing sterically demanding t-butyl amide substitution favors TSAP geometry. This chelate displayed a paraCEST signal associated with the highly shifted amide proton signal at approximately −100 ppm that was beyond the frequency of macromolecule magnetization transfer. This signal also displayed high temperature dependence (0.57 ppm °C−1) in the range of 35-42 °C and at neutral pH. Copyright © 2013 John Wiley & Sons, Ltd. ...
Serogroup X Neisseria meningitidis (MenX) has recently emerged as a cause of localized disease outbreaks in sub-Saharan Africa. In order to prepare for vaccine development, MenX polysaccharide (MenX PS) was purified by standard methods and analyzed for identity and structure by NMR spectroscopy. This study presents the first full assignment of the structure of the MenX PS using (13)C, (1)H and (31)P NMR spectroscopy and total correlation spectroscopy (TOCSY) and (1)H-(13)C heteronuclear single quantum coherence (HSQC). Molecular size distribution analysis using HPLC-SEC with multi-angle laser light scattering (MALLS) found the single peak of MenX PS to have a weight-average molar mass of 247,000g/mol, slightly higher than a reference preparation of purified serogroup C meningococcal polysaccharide. MenX PS tended to be more thermostable than serogroup A PS. A method for the quantification of MenX PS was developed by use of high performance anion exchange chromatography with pulsed amperometric detection
BACKGROUND: In vivo hepatic phosphorus-31 magnetic resonance spectroscopy (31P MRS) provides biochemical information about phosphorus metabolism. AIM: To assess 31P MRS as a prognostic marker in patients with primary biliary cirrhosis (PBC) in relation to the current clinical prognostic models. PATIENTS AND METHODS: Twenty three patients with PBC of varying functional severity and 16 matched healthy volunteers were studied using in vivo 31P MRS. Spectra were acquired using a 1.5 T spectroscopy system. Peak area ratios of phosphomonoesters (PME), inorganic phosphate (Pi), and phosphodiesters (PDE) and nucleotide triphosphate (NTP) were calculated. Pugh score, Christensen prognostic index, and R value according to the Mayo model were calculated from the clinical data. RESULTS: The PME/NTP, Pi/NTP, PME/PDE, and PME/Pi ratios and the PME signal height ratio (SHR) were significantly higher, while the PDE/NTP and PDE/SHR were significantly lower in PBC patients compared with healthy volunteers (p , ...
There is continuing interest in understanding how fuel, fuel additives, and lubricants contribute to combustion chamber deposit (CCD) weights and compositions in order to better anticipate the impact of CCD on exhaust emissions and engine performance. For this reason, we have characterized a range of CCDs from bench engines and vehicles using solid state 13C Nuclear Magnetic Resonance Spectroscopy (NMR) and X-ray Photoelectron Spectroscopy (XPS). Differences in CCD composition and structure were related to the fuel, fuel additives, and engine oil used in the test. CCDs derived from most fuels run in modern engines are predominantly organic. The fraction of aromatic carbon ranges between 24 and 74% depending on fuels and test conditions over a test length of 1,000 to 20,000 miles. These aromatic carbons exist in predominantly 1 and 2 ring structures that are independent of the amount of aromatic carbon in the CCD. These 1 and 2 ring aromatic carbon units are even present in CCD produced from ...
On MR imaging, the white matter lesions, which could be seen in the subacute stage, but not in the acute or chronic stage, might represent edema due to postinfectious neuroallergic phenomena. Immunohistochemical detection of HSV antigen is depicted in B. The sparse amount of literature on proton magnetic resonance spectroscopy in patients with herpes simplex type 1 encephalitis is discussed. Here is MRI Brain with single voxel MRI Spectroscopy. MR spectra of bilateral temporal lobes were acquired by the single voxel method using 1.5T unit. We performed MR imaging and 1H MR spectroscopy of the brain in patients with different types of primary mitochondrial diseases to investigate the role of 1H MR spectroscopy in the clinical evaluation of these disorders. Theyre usually red in colour and will develop a white head.. Although the clinical picture has been well established for some time, clinical diagnosis is attained in only 20% of the cases. Although these conditions are similar with regard to ...
Carr−Purcell−Meiboom−Gill relaxation dispersion NMR spectroscopy has evolved into a powerful approach for the study of low populated, invisible conformations of biological molecules. One of the powerful features of the experiment is that chemical shift differences between the exchanging conformers can be obtained, providing structural information about invisible excited states. Through the development of new labeling approaches and NMR experiments it is now possible to measure backbone 13Cα and 13CO relaxation dispersion profiles in proteins without complications from 13C−13C couplings. Such measurements are presented here, along with those that probe exchange using 15N and 1HN nuclei. A key experimental design has been the choice of an exchanging system where excited-state chemical shifts were known from independent measurement. Thus it is possible to evaluate quantitatively the accuracy of chemical shift differences obtained in dispersion experiments and to establish that in general ...
Phosphorus-31 nuclear magnetic resonance spectroscopy can determine the status of high energy phosphates in vivo. However, its application to human cardiac studies requires precise spatial localization without significant contamination from other tissues. Using image-selected in-vivo spectroscopy (ISIS), a technique that allows three-dimensional localization of the volume of interest, 12 subjects were studied to determine the feasibility and reproducibility of phosphorus-31 spectroscopy of the human heart. Nuclear magnetic resonance imaging was performed using a commercial 1.5 tesla system to define the volume of interest.. Phosphorus-31 spectra were obtained from the septum and anteroapical region of the left ventricle in 10 studies. Relative peak heights and areas were determined for high energy phosphates. The mean phosphocreatine to adenosine triphosphate ratio was 1.33 ± 0.19 by height analysis and 1.23 ± 0.27 by area analysis. Duplicate measurements in four subjects showed a ...
A pulsed EPR saturation-recovery method has been used to measure spin-lattice relaxation times (T 1) for aminoxyl spin labels in cardiolipin bilayers, with and without cytochrome c. The relaxation time for each spin label was determined at various positions in the bilayer, which included the bilayer surface and three positions within the hydrophobia interior in the membrane, as well as a position close to the glycerol backbone of phospholipids in the bilayer. A dynamic profile for the hydrocarbon chains in bilayers was found in agreement with results from other techniques. On addition of cytochrome c to cardiolipin bilayers, changes in the spin-lattice relaxation time and order parameter were observed around the unsaturated region in the cardiolipin acyl chains. Supported by complementary lineshape analysis, these effects were interpreted as changes in the molecular dynamics around the double bonds in the acyl chains of cardiolipin bilayers, induced upon the binding of cytochrome
Routine measurement of adipose tissue composition by repeated biopsy invokes both ethical and practical difficulties, limiting long-term serial studies of adipose tissue composition. In vivo13C nuclear magnetic resonance (NMR) spectroscopy has been applied as a non-invasive alternative, although it has not as yet been fully validated. In this study we critically assess in vivo13C NMR spectroscopy and gas-liquid chromatography for the analysis of adipose tissue composition. The advantages and drawbacks of both methods are discussed, in particular to the study of adipose tissue during dietary manipulation and development. Our results show that the NMR measurements of adipose tissue composition are highly reproducible, but they can significantly differ from those obtained by gas-liquid chromatography (GLC) from the same volunteer. We show that the discrepancy between these two techniques arises from inherent limitations of both 13C NMR spectroscopy and GLC. Finally, we show that 13C NMR ...
We studied the in vivo cerebral metabolites and documented the presence of MECP2 gene mutations in six Chinese females with Rett syndrome. Magnetic resonance spectroscopy spectra from the frontal lobe (gray and white matter) and deep gray nuclei (basal ganglia and thalamus) of either side were obtained. N-acetylaspartate/total creatine, choline/total creatine, and N-acetylaspartate/choline ratios were analyzed and compared with six healthy age-matched female control subjects. MECP2 gene mutation was identified in four patients; one patient had polymorphism and one patient did not have gene mutation. N-acetylaspartate/total creatine of the frontal lobe of all patients (mean: 2.63, S.D. = 0.33) was decreased compared with age-matched control subjects (mean: 3.15, S.D. = 0.27), and the difference was statistically significant (P = 0.017) with a mean difference of 0.52 (95% CI = 0.68-0.36). The difference in all other metabolite ratios in the frontal lobe and deep gray nuclei were not statistically ...
1NTX: SECONDARY STRUCTURE DETERMINATION FOR ALPHA-NEUROTOXIN FROM DENDROASPIS POLYLEPIS POLYLEPIS BASED ON SEQUENCE SPECIFIC PROTON NUCLEAR MAGNETIC RESONANCE ASSIGNMENTS
STRUKTURAUFKLÄRUNG (ANALYTISCHE CHEMIE); COMPUTERANWENDUNGEN IN DER CHEMIE; KOHLENSTOFF-13-KERNRESONANZSPEKTROSKOPIE; PROTONEN-KERNRESONANZSPEKTROSKOPIE; INFRAROTSPEKTROSKOPIE; MASSENSPEKTROMETRIE; STRUCTURE DETERMINATION (ANALYTICAL CHEMISTRY); COMPUTER APPLICATIONS IN CHEMISTRY; CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; INFRARED SPECTROSCOPY; MASS ...
The requested funds are forthe purchase of a new400 MHz NMR spectrometer with high throughput capabilities to underpin current research acitivity and allow the development of several new research projects. The current facilities for organic chemists are notable to meet the future requirements. The new research projects are: (a) Synthesis and screening of natural and novel antibioticJanticanceragents; (b) new methodologiesfororganicsynthesis(includingtelescoped oxidation processes, new chiral diamine ligands and new ways of generating radicals; (c) Catalysis and clean organic chemistry (including catalytically active ionicliquids; silicon-supported guanidines and new oxidation catalysts) and (d) supramolecular and biological organ icchemistry (including functional models of meta lloenzymes, supramoleculardendrimer chemistry, nanotechnology and a combinatorial approach to glycoconjugates). Several proposals are linkedto funded research programmes while others represent new initiatives. ...
Synthesis of Imidazo[1,2-a]pyridines: Triflic Anhydride-Mediated Annulation of 2H … 5.1 Spectrometry in Organic Chemistry 5-4 Types of Spectrometry (5.1A) 5-5 Mass Spectrometry (MS) Nuclear Magnetic Resonance Spectrometry (NMR) Infrared Spectrometry (IR) Ultraviolet-Visible Spectrometry (UV-Vis) 5.2 Mass Spectrometry (MS) 5-6 Formation of Molecular and Fragment Ions (5.2A) 5-6 Molecular Ion In the 1,1-dichloroethane example all the coupling constants are 6.0 Hz, as illustrated by clicking on the spectrum. This is a Carbon 13 nmr then Proton nmr. A di-substituted benzene will have 4 protons in the AR region. First, spectra taken in benzene-d6 generally show small upfield shifts of most C-H signals, but in the case of acetone this shift is about five times larger than normal. Since no two magnets will have exactly the same field, resonance frequencies will vary accordingly and an alternative method for characterizing and specifying the location of nmr signals is needed. The isomeric pairs ...
In the Lake Champlain Basin, phosphorus (P) loading from streambank erosion and cropland are both important P sources, and a better understanding of the factors affecting riparian P loss is needed to help prioritize riparian restoration efforts. We utilized solution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and an enzyme hydrolysis method to characterize P and assess bioavailability in 14 commonly mapped riparian soils from northwestern Vermont. Surface horizons were sampled from distinct series at two riparian restoration sites to capture a range of soil properties. Samples were extracted with sodium hydroxide-ethylenediaminetetra-acetic acid (NaOH-EDTA) and analyzed by solution 31P NMR to speciate and quantify P compounds, and commercially available phosphatase enzymes were used to fractionate water-extractable molybdate unreactive P (MUP) into labile orthophosphate monoesters and orthophosphate diesters. Phosphorus extracted by NaOH-EDTA ranged from 74 to 510 mg P kg-1 ...
Blumenstein, Michael (1973) I. ³¹P and ¹³C Nuclear Magnetic Resonance Studies of Nicotinamide Adenine Denucleotide and Related Compounds. II. ¹⁹F Nuclear Magnetic Resonance Studies of Rabbit Muscle Glyceraldehyde-3-Phosphate Dehydrogenase Covalently Labeled with a Trifluoromethyl Group. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0XYM-Z897. https://resolver.caltech.edu/CaltechTHESIS:11122019-135233564 ...
9. A magnetic resonance apparatus comprising:a magnetic resonance data acquisition unit comprising a basic field magnet that generates a basic magnetic field in an examination volume of the data acquisition unit;gradient coils in said data acquisition unit that generate gradient fields in the examination volume;a gradient coil unit that controls the gradient coils to generate said gradient fields;a radio-frequency transmitter that generates radio-frequency signals;a radio-frequency antenna system connected to said radio-frequency transmitter that radiates said radio-frequency signals into an examination subject located in said examination volume of said data acquisition unit, and that acquire radio-frequency signals from the examination subject that result from the radiated radio-frequency signals;a receiver unit connected to said antenna system that receives the detection radio-frequency signals;a control device that operates said gradient coil control unit, said receiver unit and said ...
TY - JOUR. T1 - Heme orientational heterogeneity in deuterohemin-reconstituted horse and human hemoglobin characterized by proton nuclear magnetic resonance spectroscopy. AU - Jue, Thomas. AU - La Mar, Gerd N.. PY - 1984/3/15. Y1 - 1984/3/15. N2 - The number of 2,4-H signals of met-cyano and deoxy deuteroheme-reconstituted sperm whale Mb are shown to reflect the known degree of heme rotational disorder in this modified protein. Using these unique spectral windows for the 2,4-H signals, we show that both horse and human Hb reconstituted with deuteroheme exhibit significant molecular heterogeneity which is consistent with approximately 20% heme rotational disorder within each subunit.. AB - The number of 2,4-H signals of met-cyano and deoxy deuteroheme-reconstituted sperm whale Mb are shown to reflect the known degree of heme rotational disorder in this modified protein. Using these unique spectral windows for the 2,4-H signals, we show that both horse and human Hb reconstituted with deuteroheme ...
In vivo nuclear magnetic resonance (NMR) spectroscopy is a non-invasive technique that can be used to investigate the metabolic response of plant tissues to anoxia. It has been used extensively in studies aimed at assessing the contribution of particular pathways to energy production and pH control during oxygen deprivation; and it is also a powerful method for investigating the origin and metabolic significance of the intracellular pH changes that occur in anoxic tissues. Recent NMR investigations of plant anaerobiosis are reviewed and it is concluded: (a) that the NMR approach provides a detailed description of the time-dependent interaction between some of the key pathways of carbon and nitrogen metabolism under anoxia; and (b) that it can provide strong evidence for the direct effect of pH on metabolism, and for the biochemical pH-stat model of the anoxic response. The significance of the NMR contribution to the understanding of plant anaerobiosis is discussed, and the possibility that the ...
The drive to develop better electrochemical energy storage devices requires the development of not only new materials, but also better understanding of the underpinning chemical and dynamical processes within such devices during operation, for which new analytical techniques are required. Currently, there are few techniques that can probe local composition and transport in the electrolyte during battery operation. In this paper, we report a novel application of magnetic resonance imaging (MRI) for probing electrochemical processes in a model electrochemical cell. Using MRI, the transport and zinc and oxygen electrochemistry in an alkaline electrolyte, typical of that found in zinc-air batteries, are investigated. Magnetic resonance relaxation maps of the electrolyte are used to visualize the chemical composition and electrochemical processes occurring during discharge in this model metal-air battery. Such experiments will be useful in the development of new energy storage/conversion devices, as ...
Compositional and structural changes within an electrolyte solution above an electrochemically active metal surface have been visualised using magnetic resonance imaging (MRI) for the first time. In these proof-of-concept experiments, zinc metal was galvanically corroded in a saturated lithium chloride solution. Magnetic resonance relaxation maps were taken during the corrosion process and spatial variations in both T1 and T2 relaxation times were observed to change with time. These changes were attributed to changes in the speciation of zinc ions in the electrolyte ...