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 ...
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.
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
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 - 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 ...
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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. ...
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 - 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 ...
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. ...
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. ...
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Proton magnetic resonance spectroscopy lactate/N-acetylaspartate within 2 weeks of birth accurately predicts 2-year motor, cognitive and language outcomes in neonatal encephalopathy after therapeutic hypothermia ...
The nuclear magnetic resonance (NMR) solution structure of free, unligated cyclophilin A (CypA), which is an 18 kDa protein from human T-lymphocytes that was expressed in Escherichia coli for the present study, was determined using multidimensional heteronuclear NMR techniques. Sequence-specific resonance assignments for 99.5% of all backbone amide protons and non-labile hydrogen atoms provided the basis for collection of an input of 4101 nuclear Overhauser enhancement (NOE) upper distance constraints and 371 dihedral angle constraints for distance geometry calculations and energy minimization with the programs DIANA and OPAL. The average RMSD values of the 20 best energy-refined NMR conformers relative to the mean coordinates are 0.49 A for the backbone atoms and 0.88 A for all heavy atoms of residues 2 to 165. The molecular architecture includes an eight-stranded antiparallel beta-barrel that is closed by two amphipathic alpha-helices. Detailed comparisons with the crystal structure of free ...
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Two-dimensional nuclear magnetic resonance relaxation correlation studies of cement pastes have been performed on a unilateral magnet, the Surface GARField. Through these measurements, the hydration process can be observed by monitoring the evolution of porosity. Characteristic relaxation time distributions have been observed in different cement pastes: fresh white cement, prehydrated white cement and ordinary Portland cement. The observed T-1/T-2 ratio in these cements has been shown to agree with expectations based on high field values. (C)) 2007 Elsevier Inc. All rights reserved.. ...
Magnetic resonance spectroscopy enables insight into the chemical composition of spinal cord tissue. However, spinal cord magnetic resonance spectroscopy has rarely been applied in clinical work due to technical challenges, including strong susceptibility changes in the region and the small cord diameter, which distort the lineshape and limit the attainable signal to noise ratio. Hence, extensive signal averaging is required, which increases the likelihood of static magnetic field changes caused by subject motion (respiration, swallowing), cord motion, and scanner-induced frequency drift. To avoid incoherent signal averaging, it would be ideal to perform frequency alignment of individual free induction decays before averaging. Unfortunately, this is not possible due to the low signal to noise ratio of the metabolite peaks. In this article, frequency alignment of individual free induction decays is demonstrated to improve spectral quality by using the high signal to noise ratio water peak from ...
Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder primarily affecting young boys, often causing mental retardation in addition to the well-known progressive muscular weakness. Normal dystrophin expression is lacking in skeletal muscle and the central nervous system (CNS) of both DMD children and the mdx mouse model. The underlying biochemical lesion causing mental impairment in DMD is unknown. 1H-magnetic resonance spectroscopy (1H-MRS) detects choline-containing compounds, creatine and N-acetyl aspartate (NAA) in vivo. NAA is commonly used as a chemical marker for neurons, and a decline in NAA is thought to correlate with neuronal loss. Control mice were compared to mdx using a combination of in vivo and in vitro 1H-MRS methods to determine whether neural necrosis or developmental abnormalities occur in dystrophic brain. NAA levels were normal in mdx brain compared to controls suggesting minor, if any, neuronal necrosis in dystrophic brain. In contrast, choline compounds and myo
Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder primarily affecting young boys, often causing mental retardation in addition to the well-known progressive muscular weakness. Normal dystrophin expression is lacking in skeletal muscle and the central nervous system (CNS) of both DMD children and the mdx mouse model. The underlying biochemical lesion causing mental impairment in DMD is unknown. 1H-magnetic resonance spectroscopy (1H-MRS) detects choline-containing compounds, creatine and N-acetyl aspartate (NAA) in vivo. NAA is commonly used as a chemical marker for neurons, and a decline in NAA is thought to correlate with neuronal loss. Control mice were compared to mdx using a combination of in vivo and in vitro 1H-MRS methods to determine whether neural necrosis or developmental abnormalities occur in dystrophic brain. NAA levels were normal in mdx brain compared to controls suggesting minor, if any, neuronal necrosis in dystrophic brain. In contrast, choline compounds and myo
NUCLEAR MAGNETIC RESONANCE IMAGING + NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY (MEDICAL DIAGNOSTICS); NMR-MIKROSKOPIE, NMR-ABBILDUNDSVERFAHREN; CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; NUTRITION + NUTRITIONAL SCIENCE; BONE MARROW (CYTOLOGY, HISTOLOGY); KNOCHENMARK (CYTOLOGIE, HISTOLOGIE); ERNÄHRUNG + ERNÄHRUNGSWISSENSCHAFT; FETTSÄUREN (BIOCHEMIE); FATTY ACIDS (BIOCHEMISTRY); MUSKELZELLEN (CYTOLOGIE, HISTOLOGIE); KOHLENSTOFF-13-KERNRESONANZSPEKTROSKOPIE; KERNSPINRESONANZ-ABBILDUNGSVERFAHREN + KERNSPINRESONANZ-TOMOGRAPHIE (MEDIZINISCHE DIAGNOSTIK); MUSCLE CELLS (CYTOLOGY, HISTOLOGY); NMR MICROSCOPY, NMR ...
Equivalent cross-relaxation rate (ECR) and cellular density. Regression graph: cellular density is plotted along vertical axis, while equivalent cross-relaxatio
This thesis describes several novel in-vivo proton magnetic resonance spectroscopy (MRS) techniques used to study the human brain. By measuring brain metabolites non-invasively, MRS has provided seminal contributions to our fundamental understanding of the brain as well as a wide variety of clinical conditions. However, due to the relative insensitivity and low spectral resolution of MRS, many important brain metabolites cannot be accurately quantified under standard clinical conditions. One way of in- creasing both the sensitivity and spectral resolution of MRS is to increase the static magnetic field strength. Unfortunately, increasing the static magnetic field strength also creates new technical challenges that must be resolved before any gains associated with higher magnetic field strength can be achieved. Due to increased shimming requirements and hardware limitations, many MRS experiments at higher magnetic fields are performed on a single voxel in the brain - thereby limiting any possible ...
Brine, G., Boldt, K., Huang, P-T., Sawyer, D., & Carroll, F. (1989). Carbon-13 Nuclear Magnetic Resonance Spectra of Fentanyl Analogs. Journal of Heterocyclic Chemistry, 26, 677 ...
TY - JOUR. T1 - Hyphenation of capillary separations with nuclear magnetic resonance spectroscopy. AU - Jayawickrama, Dimuthu A.. AU - Sweedler, Jonathan V.. PY - 2003/6/6. Y1 - 2003/6/6. N2 - The hyphenation of small-volume separations to information-rich detection offers the promise of unmatched analytical information on the components of complex mixtures. Nuclear magnetic resonance (NMR) spectroscopy provides information about molecular structure, although sensitivity remains an issue for on-line NMR detection. This is especially true when hyphenating NMR to capillary separations as the observation time and analyte mass are decreased to the point where reduced information is obtained from the eluting analytes. Because of these limitations, advances in instrumental performance have a large impact on the overall performance of a separation-NMR system. Instrumental aspects and the capabilities of cLC-NMR, CEC-NMR and CE-NMR are reviewed, and applications that have used this technology ...
A multinuclear (1H, 13C, 31P and 195Pt) magnetic resonance spectroscopy study of mixed ligand platinum(II) complexes with new N,N-dialkyl-N-acyl(aroyl)thioureas as ...
View Notes - lec7_handout from CHEMICAL E 20.410j at MIT. Notes for Lecture #7 1 H NMR Spectroscopy - Chemical Shift Regions of the 1 H NMR Spectrum
Magnetic resonance spectroscopy and imaging experiments in which spatial dynamics (diffusion and flow) closely coexists with chemical and quantum dynamics (spin-spin couplings, exchange, cross-relaxation, etc.) have historically been very hard to simulate - Bloch-Torrey equations do not support complicated s 2017 PCCP HOT Articles
Magnetic resonance spectroscopy (MRS) is commonly applied in medicine with 1H proton or 31-phosphorus spectra. The proton MRS is often used in evaluating the central nervous system and 31P MRS is used in muscular diseases or neoplasms. However, the proton MRS is also considered to be applied to the musculoskeletal system because of its profound amount of protons. Ballon used the STEAM technique, and Schick used the PRESS technique, to investigate the lipid and water spectra of the bone marrow and also correlated those with hematological diseases and post-treatment effects. Schellinger et al. used the STEAM sequence to calculate the lipid content of the vertebral bone marrow and found that it was influenced according to age and sex. The investigator had used the proton MRS to evaluate the lipid and water spectra of the femoral head and revealed its significance in predicting avascular necrosis of the femoral head. According to the above research literature, the investigators considered further ...
Early estimation of bull fertility is highly desirable for the conservation of male genetics of endangered species and for the exploitation of genetically superior sires in artificial insemination programs. The present work was conducted as a proof-of-principle study to identify fertility-associated metabolites in dairy bull seminal plasma and blood serum using proton nuclear magnetic resonance (1H NMR). Semen and blood samples were collected from high- and low-fertility breeding bulls (n = 5 each), stationed at Semex, Guelph, Canada. NMR spectra of serum and seminal plasma were recorded at a resonance frequency of 500.13 MHz on a Bruker Avance-500 spectrometer equipped with an inverse triple resonance probe (TXI, 5 mm). Spectra were phased manually, baseline corrected, and calibrated against 3-(trimethylsilyl) propionic-2,2,3,3-d4 acid at 0.0 parts per million (ppm). Spectra were converted to an appropriate format for analysis using Prometab software running within MATLAB. Principal component ...
TY - JOUR. T1 - Changes in calmodulin main-chain dynamics upon ligand binding revealed by cross-correlated NMR relaxation measurements. AU - Wang, Tianzhi. AU - Frederick, Kendra King. AU - Igumenova, Tatyana I.. AU - Wand, A. Joshua. AU - Zuiderweg, Erik R P. PY - 2005/1/26. Y1 - 2005/1/26. N2 - The fast dynamics of protein backbones are often investigated by nuclear magnetic relaxation experiments that report on the degree of spatial restriction of the amide bond vector. By comparing calmodulin in the peptide-bound and peptide-free states with these classical methods, we observe little difference in the dynamics of the polypeptide main chain (average order parameter decrease of 0.01 unit upon binding). However, when using NMR methods that monitor the mobility of the CO-Cα bond vector, we reveal a significant reduction of dynamics of the protein main chain (average order parameter decrease of 0.048 units). Previous investigations have suggested that the side-chain dynamics is reduced by an ...
1H NMR-based metabolite profiling workflow to reduce inter-sample chemical shift variations in urine samples for improved biomarker ...
A magnetic resonance method includes performing a plurality of magnetic resonance excitation operations each using a different sub-set of a set of radio frequency transmit coils (30), each sub-set including more than one radio frequency transmit coil, acquiring magnetic resonance data responsive to each said magnetic resonance excitation operation, and computing a B1 or flip angle map for each radio frequency transmit coil of the set of radio frequency transmit coils based on the acquired magnetic resonance data. A magnetic resonance method includes performing an actual flip angle mapping (AFI) sequence using a radio frequency transmit coil (32) with a ratio TR1:TR2 of the TR times of the AFI sequence selected to be rational, acquiring magnetic resonance data responsive to said AFI sequence, and computing a B1 or flip angle map for the radio frequency transmit coil based on the acquired magnetic resonance data.
Exploratory metabolomics studies of cerebrospinal fluid (CSF), using proton nuclear magnetic resonance (1H NMR) spectroscopy, hold major potential application in neurodiagnostics. Such studies, however, rely upon established databases of known metabolites. Here we address the unknowns in the 1H NMR spectra of CSF from treated pediatric meningitis cases. Through knowledge of the clinical information given by the pediatrician and analytical application of 1H NMR spectroscopy on pure reference compounds of the medication used, we identified four of the previously unknown compounds in the 1H NMR CSF spectra - the drugs pyrazinamide, isoniazid, acyclovir, and sulfamethoxazole. We report on the one- and two-dimensional 1H NMR spectral data and chemical information of these four compounds. By expanding our knowledge of 1H NMR CSF spectra from treated meningitis cases, we are able to bring 1H NMR closer to the forefront of ...
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An aromatic ring current is an effect observed in aromatic molecules such as benzene and naphthalene. If a magnetic field is directed perpendicular to the plane of the aromatic system, a ring current is induced in the delocalized π electrons of the aromatic ring.[1] This is a direct consequence of Ampères law; since the electrons involved are free to circulate, rather than being localized in bonds as they would be in most non-aromatic molecules, they respond much more strongly to the magnetic field.. Aromatic ring currents are relevant to NMR spectroscopy, as they dramatically influence the chemical shifts of 13C and 1H nuclei in aromatic molecules,[2] as well as in any organic or inorganic aromatic molecule. The effect helps distinguish these nuclear environments and is therefore of great use in molecular structure determination. In benzene, the ring protons experience deshielding because the induced magnetic field has the same direction as the external field and their chemical shift is 7.3 ...
In this study, a set of nuclear magnetic resonance experiments, some of them commonly used in the study of C-13-labeled proteins and/or nucleic acids, is applied for the structure determination of uniformly C-13-enriched carbohydrates. Two model substances were employed: one compound of low molecular weight [(UL-C-13)-sucrose, 342 Da] and one compound of medium molecular weight (C-13-enriched O-antigenic polysaccharide isolated from Escherichia coli O142, similar to 10 kDa). The first step in this approach involves the assignment of the carbon resonances in each monosaccharide spin system using the anomeric carbon signal as the starting point. The C-13 resonances are traced using C-13-C-13 correlations from homonuclear experiments, such as (H)CC-CT-COSY, (H)CC-NOESY, CC-CT-TOCSY and/or virtually decoupled (H)CC-TOCSY. Based on the assignment of the C-13 resonances, the H-1 chemical shifts are derived in a straightforward manner using one-bond H-1-C-13 correlations from heteronuclear experiments ...
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Direct measurement of piezoelectric field in In[sub 0.23]Ga[sub 0.77]N/GaN multiple quantum wells by electrotransmission spectroscopy. Lai, C. Y.; Hsu, T. M.; Chang, W.-H.; Tseng, K.-U.; Lee, C.-M.; Chuo, C.-C.; Chyi, J.-I. // Journal of Applied Physics;1/1/2002, Vol. 91 Issue 1, p531 In this communication, we present experimental evidence of the piezoelectric-field-induced quantum-confined Stark effect on In[sub 0.23]Ga[sub 0.77]N/GaN multiple quantum wells. The optical transitions in In[sub 0.23]Ga[sub 0.77]N/GaN p-i-n multiple quantum wells were studied by using... ...
Monosodium L-glutamate monohydrate, a multiple oxygen site (eight) compound, is used to demonstrate that a combination of high-resolution solid-state NMR spectroscopic techniques opens up new possibilities for (17)O as a nuclear probe of biomolecules. Eight oxygen sites have been resolved by double rotation (DOR) and multiple quantum (MQ) NMR experiments, despite the (17)O chemical shifts lying within a narrow shift range of |50 ppm. (17)O DOR NMR not only provides high sensitivity and spectral resolution, but also allows a complete set of the NMR parameters (chemical shift anisotropy and electric-field gradient) to be determined from the DOR spinning-sideband manifold. These (17)O NMR parameters provide an important multi-parameter comparison with the results from the quantum chemical NMR calculations, and enable unambiguous oxygen-site assignment and allow the hydrogen positions to be refined in the crystal lattice. The difference in sensitivity between DOR and MQ NMR experiments of oxygen in bio
Nuclear magnetic resonance spectra (proton and phosphorus-31) and ultraviolet absorption spectra of the DNA decamer d(br5CGbr5CGATbr5CGbr5CG), in which the central two adenine-thymine base pairs are out of order with the rest of the purine-pyrimidine alternation sequence, indicate that under appropriate solvent conditions (high salt and methanol) the molecule undergoes a structural transition from a right-handed B-DNA conformation to a left-handed Z-DNA conformation. Measurements of the two-dimensional nuclear Overhauser effect on the decamer indicate that all of the guanines as well as the two equivalent thymines adopt the syn conformation. ...
View Notes - lecture25_2011 from CH 21b at Caltech. 04Mar2011 Chemistry 21b - Spectroscopy Lecture # 25 - Nuclear Magnetic Resonance Spectroscopy Along with infrared spectroscopy, nuclear
A double quantum filter is inserted into a 2-dimensional correlated (COSY) 1H NMR expt. to obtain phase-sensitive spectra in which both cross-peak and diagonal-peak multiplets have antiphase fine structure, and in which the cross peaks and the major contribution to the diagonal peaks have absorption lineshapes in both dimensions. The elimination of the dispersive character of the diagonal peaks in phase-sensitive, double quantum-filtered COSY spectra allows identification of cross peaks lying immediately adjacent to the diagonal, which represents a significant improvement over the conventional COSY expt. [on SciFinder (R)]. ...
Strukturer af Supramolekylær protein forsamlinger på atomare opløsning er for høj relevans på grund af deres afgørende roller i en...
Abstract: Using 13C solid-state nuclear magnetic resonance(NMR) we studied the structures of two spidroin-like polymers which were synthesized by the polymerization of polyalanine ((Ala)5) with oligomers of polystyrene(PS, MW=2000) and polyisoprene(PI, MW=2210). 13C CP/MAS (cross polarization/magic angle spinning) NMR spectra and spin-lattice relaxation time in the rotating frame (T1ρ(13C)) results of the polymers indicated that the chemical shifts of (Ala)5 in both polymers of polystyrene-co-polyalanine (PS-co-PAL) and polyisoprene-co-polyalanine (PI-co-PAL) were almost the same. This means that (Ala)5 peptide segments in the two polymers have similar chemical environments and secondary structures. The similar T1ρ(13C) values for (Ala)5 in the two polymers indicate that (Ala)5 peptide segments also have similar aggregate structures. The mechanical properties of the two spidroin-like polymers are quite different: PS-co-PAL is granular and tough while PI-co-PAL is rubber-like and tensible at ...
Our laboratory improves magnetic resonance technology and spectroscopy for biomolecular structure determination relevant to HIV cure research. Solid state nuclear magnetic resonance (NMR) is exquisitely suited to probe atomic level structural detail of biomolecules within intact human cells. However, the small nuclear magnetic moments that yield narrow resonances also result in very low inherent sensitivity in NMR. Dynamic Nuclear Polarization (DNP) is a powerful combined electron paramagnetic resonance (EPR) and NMR technique that transfers the strong polarization from unpaired electron spins to nuclear spins to boost NMR sensitivity. In our DNP experiments, we employ frequency agile gyrotrons, and extreme cryogenic sample cooling to increase the sensitivity of solid state NMR experiments up to a factor of 20,000. This tremendous gain in sensitivity results in acquiring data 400 million times faster than conventional NMR experiments and will have a profound impact on magnetic resonance ...
For the assessment of TKE, 4D PC-MRI data were acquired during free breathing on a clinical 1.5-T MR scanner (Siemens Avanto, Siemens, Erlangen, Germany) using a prospectively cardiac-gated gradient echo sequence with asymmetrical 4-point motion encoding, where the latter enables TKE estimation (16). Respiratory effects were suppressed by using navigator gating with a 7-mm acceptance window. Other imaging parameters included TR/TE: 4.3 to 4.4/2.7 to 2.9 ms, flip angle: 8°, k-space segmentation factor: 2, parallel imaging reduction factor: 2. The 3-dimensional field-of-view (240 to 360 × 240 to 360 × 55 to 80 mm3) and matrix size (96 to 144 × 96 to 144 × 22 to 32) was adjusted depending on each subjects anatomy to cover the thoracic aorta with a sagittal-oblique slab orientation while maintaining an isotropic voxel size of 2.5 × 2.5 × 2.5 mm3. Total scan time was about 10 to 25 min, depending on the navigator efficiency. On the basis of previous in vivo studies with MR TKE mapping, we ...
Dynamic Nuclear Polarization (DNP) is often achieved by the direct transfer of polarization from electrons to nuclei such as C-13, induced by microwave saturation of the wings of narrow EPR lines of radicals like trityl. In the indirect approach on the other hand, DNP is used to transfer the polarization from the electrons of radicals such as nitroxides that have broad EPR lines to nuclear spins I = H-1, followed by cross-polarization (CP) from I = H-1 to S = C-13 or other nuclei with low gyromagnetic ratios. This approach is particularly attractive for S = N-15, since direct DNP yields modest polarizations P(N-15) , 4% with build-up times that can be as long as tau DNP(N-15) , 2 h. In this paper, we show that CP from H-1 to N-15 at 1.2 K can yield P(N-15) = 25% with iota CP-DNP(N-15) = 10-15 min. After rapid dissolution and transfer to a solution-state NMR spectrometer, a polarization P(N-15) = 20% was observed at 300 K. The longitudinal relaxation times in solution can be as long as T-1(N-15) ...
Cyr, N.; Vodny, S.; and Micko, M.M., "Application of nuclear magnetic resonance spectroscopy for chemical characterization of Aspen poplar lignin" (1985). ...
The slides used in this presentation borrow heavily from the great downloadable: Chapter 13 Nuclear Magnetic Resonance Spectroscopy Organic Chemistry, 5th ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 729304-ODA3Z
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In this work, a combination of methods, predominantly solid state nuclear magnetic resonance (NMR), is used to characterize the properties of a solid acid material. Solid state NMR was used to determine the degree of proton transfer from the acid site to an adsorbed base molecule. Theoretical models of these interactions were constructed and computational calculations were used in conjunction with experiment to determine the theoretical structure bond distances, structural geometries, and relative energies. The theoretical models were also used to predict NMR parameters subsequently used to simulate the NMR line shapes.; The first chapter of this thesis provides an introduction to the materials and techniques used including solid-state magic angle spinning (MAS) NMR and Density Functional Theory (DFT). The second chapter expands on the first chapter through the experimental and theoretical investigation of the effect of proton transfer on the 71Ga line shape in a gallium substituted zeolite ...
Magnetic resonance imaging (MRI) is a diagnostic study that makes pictures of organs of the body using magnetic field and radio frequency pulses that can not be felt. Dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) uses faster imaging and contrast material (a substance used to make specific organs, blood vessels, or tumors easier to see) that is given by vein. Diffusion weighted magnetic resonance imaging (DW-MRI) allows to measure the motion of water around the cells in the tumor. Proton magnetic resonance spectroscopy (MRS) obtains chemical information from the tumor. During MRS, signals are detected from the chemicals (spectroscopy) naturally present in your tumor using radio waves. DCE-MRI, DW-MRI and MRS give extra information which is not available with the regular MRI. The regular MRI only shows pictures of the tumor while the DCE-MRI also gives information about the blood vessels of the tumor. DW-MRI provides information related to the state of the tumor tissue with ...
Dynamic nuclear polarization (DNP) NMR spectroscopy, a high-polarization method, is rapidly changing the landscape of what is possible in solid-state nuclear magnetic resonance spectroscopy. To date,
We describe a new fivefold symmetric approach to homonuclear recoupling in rotating solids that is based on rotor-synchronized, spin-lock rf irradiation of the type employed previously in MELODRAMA and C7 ~and their derivative sequences! for C- C recoupling. The fivefold sequence, like its sevenfold relatives, is g-encoded, and therefore exhibits a theoretical efficiency of ;73% for double quantum filtering ~2QF!. However, since the ratio of rf field strength, v rf/2p , to spinning frequency, vr/2p , is lower, it is possible to operate the sequence at higher spinning rates, and we have investigated the 2QF efficiency as a function of H decoupling field strength at high spinning frequencies. We observe dramatic oscillations of the recoupled signal with a period ;vr/2p indicating that the H reservoir is behaving partially inhomogeneously. This kind of double quantum recoupling is explored in multiple spin systems and we derive analytical forms for polarization transfer and double quantum excitation
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Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup ...
Divalent cations are important in the folding and stabilization of complex RNA structures. The adenine-sensing riboswitch controls the expression of mRNAs for proteins involved in purine metabolism by directly sensing intracellular adenine levels. Adenine binds with high affinity and specificity to the ligand binding or aptamer domain of the adenine-sensing riboswitch. The X-ray structure of this domain in complex with adenine revealed an intricate RNA-fold consisting of a three-helix junction stabilized by long-range base-pairing interactions and identified five binding sites for hexahydrated Mg2+-ions. Furthermore, a role for Mg2+-ions in the ligand-induced folding of this RNA was suggested. Here, we describe the interaction of divalent cations with the RNA-adenine complex in solution as studied by high-resolution NMR spectroscopy. Paramagnetic line broadening, chemical shift mapping and intermolecular nuclear Overhauser effects (NOEs) indicate the presence of at least three binding sites for ...
This book provides a complete exposition of the theory of nuclear magnetic relaxation caused by the thermal motion of the molecule containing the relaxing nucleus. The author begins by defining the physical quantities encountered in nuclear magnetic resonance studies and surveying pioneering investigations in the field. Nuclear magnetic relaxation by scalar, dipolar, quadrupolar and spin-rotational interactions and by anisotropic chemical shift are then examined in detail. Relaxation rates are expressed in terms of spectral densities, and the values of the spectral densities for various molecular shapes are calculated by random walk or Brownian motion dynamics. The text should be within the grasp of readers who have taken undergraduate courses in electromagnetic theory and in classical and quantum mechanics, although topics in these fields of particular relevance are to be found in appendices. This book will be of value to postgraduate students and research workers using n.m.r. in physics and ...
/sup 1/H spectra of TGS crystals were performed using WM-400 Bruker spectrometer winch revealed three signals identified as water, COOH and NH/sub 2/ sig
Dynamic nuclear polarization (DNP) transfers electron spin-polarization to nuclear spins in close proximity, increasing sensitivity by two-to-three orders of magnitude. This enables nuclear magnetic resonance (NMR) experiments on samples with low concentrations of analyte. The requirement of using cryogenic temperatures in DNP-enhanced solid-state NMR (ssNMR) experiments may impair the resolution and hence limit its broad application to biological systems. In this work, we introduce a "High-Temperature DNP" approach, which aims at increasing spectral resolution by performing experiments at temperatures of around 180 K instead of ~100 K. By utilizing the extraordinary enhancements obtained on deuterated proteins, still sufficiently large DNP enhancements of 11-18 are obtained for proton and carbon, respectively. We recorded high sensitivity 2D 13 C- 13 C spectra in ~9 min with higher resolution than at 100 K, which has similar resolution to the one obtained at room temperature for some favorable ...
Methods-We measured tissue pH and phospholipid as well as cell energy markers, including creatine, phosphocreatine, and N-acetyl-aspartate in subacute stroke with combined 1H and 31P magnetic resonance spectroscopy. We included 19 patients with first-ever ischemic stroke (mean time after stroke, 6 days). We then compared metabolite concentrations in the ischemic tissue to contralateral (healthy) tissue using multivariate ANOVA to assess significant differences in metabolite levels between both tissue compartments.. ...
1.Chen GQ, Wu Q. 2005. The application of polyhydroxyalkanoates as tissue engineering materials. Biomaterials. 26:6565-6578 2. Doi Y, Kunioka M, Nakamura Y, Soga K. 1986. Nuclear magnetic resonance studies on poly(B-hydroxybutyrate) and a copolyester of B-hydroxybutyrate and B-hydroxyvalerate isolated from Alcaligenes eutrophus H16. Macromolecules. 19:2860-2864 3. Endy D. 2005. Foundations for engineering biology. Nature. 438(7067):449-53 4. International Genetically Engineered Machines competition. 15 Jun 2008. 26 Jul 2008. ,http://igem.org, 5. Holmes PA. 1985. Applications of PHB - a microbially produced biodegradable thermoplastic. Physics in technology. 16:32-36 6. Kang Z, Wang Q, and H Zhang. 2008. Construction of a stress-induced system in Escherichia coli for efficient polyhydroxyalkanoates production. Biotechnological Products and Process Engineering. 79:203-208 7. Knight TF. 2003. Idempotent Vector Design for Standard Assembly of BioBricks. Tech. rep., MIT Synthetic Biology Working ...
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We applied novel methodology to enable a more detailed evaluation of mitochondrial function as affected by insulin-deficient diabetes. There are several advantages to our ATP assay. First, the assay is performed under clamped ΔΨ, allowing assessment of ATP as a function of its direct driving force, ΔΨ. Second, our assay is sensitive enough to measure ATP production in small isolates of mitochondria. As indicated in Supplementary Figs. 2 and 3, the one-dimensional 1H NMR method is 34-fold more sensitive and the two-dimensional 1H/13C HSQC NMR method is 41-fold more sensitive when compared with one-dimensional 31P NMR for ATP detection. The high sensitivity of the two-dimensional NMR method is attributable to the fact that the chemical shifts of the two H6 protons of the β-anomeric form of 2DOGP are degenerate, resulting in detection of one single C6/H6 HSQC cross-peak with high intensity. Third, both the one-dimensional and two-dimensional NMR spectra are highly specific. In particular, the ...
This proposal requests funds to acquire a console and cold probe for a 600MHz NMR spectrometer to support biomolecular research at Weill Cornell Medical College...
The temperature-induced helix-to-coil conformational transition accompanying the thermoreversible gelation of syndiotactic poly(methyl methacrylate) in toluene was studied by rheology and FTIR and H-1 NMR spectroscopy. Both rheological and FTIR measurements, carried out dynamically as a function of temperature, revealed a marked hysteresis between the heating and the cooling cycles. It was not possible to assess a quantitative difference between the values of the temperature of onset of the physical variations between the rheological and the spectroscopic experiments. It is then possible to conclude that a conformational change of the backbone (from the evolution of the band at 860 cm(-1)) is the molecular basis of the macroscopic formation of the gel. Spin-spin relaxation time, or T-2, measurements were used in the H-1 NMR study. The data obtained from the relaxation behavior of the a-methyl group, indicated a fraction of 0.28 for the chain repeating units incorporated in highly cooperative ...
The exchangeable and non-exchangeable protons are usually assigned to their specific peaks as two independent groups. For exchangeable protons, which are for the most part the protons involved in base pairing, NOESY can be used to find through-space correlations between on neighboring bases, allowing an entire duplex molecule to be assigned through sequential walking. For nonexchangable protons, many of which are on the sugar moiety of the nucleic acid, COSY and TOCSY are used to identify systems of coupled nuclei, while NOESY is again used to correlate the sugar to the base and each base to its neighboring base. For duplex DNA nonexchangeable protons the H6/H8 protons on the base correlate to their counterparts on neighboring bases and to the H1 proton on the sugar, allowing sequential walking to be done. For RNA, the differences in chemical structure and helix geometry make this assignment more technically difficult, but still possible. The sequential walking methodology is not possible for ...
Biomedical Graduate Studies (BGS) serves as the academic home within the University of Pennsylvania for roughly 700 graduate students pursing a PhD in the basic biomedical sciences.
The monosaccharide L-rhamnose is common in bacterial polysaccharides and the disaccharide alpha-L-Rhap-alpha-(1 -, 2)-alpha-L-Rhap-OMe represents a structural model for a part of Shigella flexneri O-antigen polysaccharides. Utilization of [1-C-13]-site-specific labeling in the anomeric position at the glycosidic linkage between the two sugar residues facilitated the determination of transglycosidic NMR (3)J(CH) and (3)J(CC) coupling constants. Based on these spin-spin couplings the major state and the conformational distribution could be determined with respect to the psi torsion angle, which changed between water and dimethyl sulfoxide (DMSO) as solvents, a finding mirrored by molecular dynamics (MD) simulations with explicit solvent molecules. The C-13 NMR spin relaxation parameters T-1, T-2, and heteronuclear NOE of the probe were measured for the disaccharide in DMSO-d(6) at two magnetic field strengths, with standard deviations ,= 1%. The combination of MD simulation and a stochastic ...
The synthesis of [2-3H]ATP with specific activity high enough to use for 3H NMR spectroscopy at micromolar concentrations was accomplished by tritiodehalog
Spectral resolution in proton NMR spectroscopy is reduced by the splitting of resonances into multiplets due to the effect of homonuclear scalar couplings. Although these effects are often hidden in protein NMR spectroscopy by low digital resolution and routine apodization, behind the scenes homonuclear scalar couplings increase spectral overcrowding. The possibilities for biomolecular NMR offered by new pure shift NMR methods are illustrated here. Both resolution and sensitivity are improved, without any increase in experiment time. In these experiments, free induction decays are collected in short bursts of data acquisition, with durations short on the timescale of J-evolution, interspersed with suitable refocusing elements. The net effect is real-time (t (2)) broadband homodecoupling, suppressing the multiplet structure caused by proton-proton interactions. The key feature of the refocusing elements is that they discriminate between the resonances of active (observed) and passive (coupling ...
We propose a molecular model for phospholipid membrane lysis by the ubiquitous plant toxins called thionins. Membrane lysis constitutes the first major effect exerted by these toxins that initiates a cascade of cytoplasmic events leading to cell death. X-ray crystallography, solution nuclear magnetic resonance (NMR) studies, small angle X-ray scattering and fluorescence spectroscopy provide evidence for the mechanism of membrane lysis. In the crystal structures of two thionins in the family, alpha(1)- and beta-purothionins (MW: approximately 4.8 kDa), a phosphate ion and a glycerol molecule are modeled bound to the protein. (31)P NMR experiments on the desalted toxins confirm phosphate-ion binding in solution. Evidence also comes from phospholipid partition experiments with radiolabeled toxins and with fluorescent phospholipids. This data permit a model of the phospholipid-protein complex to be built. Further, NMR experiments, one-dimensional (1D)- and two-dimensional (2D)-total correlation spectroscopy
Brain tumor news: Use of magnetic resonance spectroscopy (MRS) in malignant gliomas treated with temozolomide (TMZ) MRS may increase sensitivity of traditional MRI techniques for detecting tumor progression or response and our observations of tumor response by MRI suggest that multi-voxel MRS is crucial to evaluating response for inhomogeneous tumors (such as oligodendrogliomas).
Results of studies of 4,4-di-n-heptylazoxybenzene (HAB) in the isotropic, nematic and smectic A phases are presented. Two experimental methods were employed: broad band dielectric spectroscopy and nuclear magnetic resonance spectroscopy. The complex dielectric permittivity, epsilon*(omega)= epsilon(omega) iepsilon(omega), was measured in the frequency range 1 kHz - 4 GHz. This allowed two main relaxation processes to be separated in all the phases studied: the low frequency (l.f.) process connected with molecular reorientations around the short axes, and the high frequency ( h.f.) process connected with the rotations around the long axes. The corresponding relaxation times and activation enthalpies were obtained. The l.f. relaxation time changes step-wise at the phase transitions, whereas the h.f. relaxation time passes smoothly through all the phases. The measurement of H-2 spin-lattice relaxation times was carried out throughout the mesophase range at 61.38 MHz. These data were analysed ...
TY - JOUR. T1 - Proton magnetic resonance spectroscopic imaging in neurodegenerative diseases. AU - Schuff, Norbert. AU - Vermathen, Peter. AU - Maudsley, Andrew A. AU - Weiner, Michael W.. PY - 1999/3/25. Y1 - 1999/3/25. N2 - Proton magnetic resonance spectroscopic imaging (1H MRSI) was used to investigate changes in brain metabolites in Alzheimers disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1H MRSI of the human brain, without volume preselection offers considerable advantage over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectral curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtain full volumetric brain coverage and data acquisition at short spin-echo times (TE , 30 ms) for the detection of metabolites.. AB - Proton magnetic resonance spectroscopic imaging (1H MRSI) was used to investigate changes in ...
Energy metabolism in the Wistar rat brain was studied by means of in vivo nuclear magnetic resonance spectroscopy after heating. The 31P-spectra were recorded at 10 minutes after heating the brain to 44 or 45℃ (cortical temperature) for 30 minutes on 6 rats in each group. Thereafter, the 31P-spectra were repeatedly recorded until 1 hour after heating. The 31P-spectra showed no significant changes of pH and high-energy phosphate levels occurred for 1 hour after heating of the brain to 44℃ for 30 minutes. However, those determined 10 minutes after heating the brain to 45℃ for 30 minutes showed a statistically significant reduction of the PCr/Pi ratio without accompaning a pH shift and change in ATP concentration. No further changes occurred thereafter for 1 hour after heating of the brain. The heat-induced PCr/Pi ratio reduction observed in this study reflected mitochondrial dysfunction and not a decline in cerebral blood flow. The present study has demonstrated at least part of the ...
Background: The multiple sclerosis (MS) severity scale (MSSS) is a new scoring procedure to clinically characterize the rate of disease progression in MS, rather than the disability of the patient. The latter is often characterized using the expanded disability status score (EDSS). The progress rate of the disease, magnetic resonance imaging (MRI)-based measures of black hole lesions, and atrophy have all been shown to be predicted well by MSSS. In this study we investigated possible relationships between brain metabolite concentrations, measured using proton (1H) magnetic resonance spectroscopy (MRS), and MSSS.. Purpose: Our aims were to quantitatively investigate the metabolite concentrations in normal appearing white matter (NAWM) in MS-patients, and also to investigate possible correlations between disease subtype, EDSS and MSSS and metabolite concentrations. To minimize the interference from lesion contamination in the MRS measurement, a refined novel analysis procedure had to be ...
Background: The multiple sclerosis (MS) severity scale (MSSS) is a new scoring procedure to clinically characterize the rate of disease progression in MS, rather than the disability of the patient. The latter is often characterized using the expanded disability status score (EDSS). The progress rate of the disease, magnetic resonance imaging (MRI)-based measures of black hole lesions, and atrophy have all been shown to be predicted well by MSSS. In this study we investigated possible relationships between brain metabolite concentrations, measured using proton (1H) magnetic resonance spectroscopy (MRS), and MSSS.. Purpose: Our aims were to quantitatively investigate the metabolite concentrations in normal appearing white matter (NAWM) in MS-patients, and also to investigate possible correlations between disease subtype, EDSS and MSSS and metabolite concentrations. To minimize the interference from lesion contamination in the MRS measurement, a refined novel analysis procedure had to be ...