Nuclear Magnetic Resonace Research Articles

Development of the Integrated Computer Simulation Model of the Intracellular, Transmembrane, and Extracellular Domain of Platelet Integrin α IIb β 3 (Platelet Membrane Glycoprotein: GPIIb-IIIa).

Background The structure and functions of the extracellular domain of platelet integrin α IIb β 3 (platelet membrane glycoprotein: GPIIb-IIIa) change substantially upon platelet activation. However, the stability of the integrated model of extracellular/transmembrane/intracellular domains of integrin α IIb β 3 with the inactive state of the extracellular domain has not been clarified. Methods The integrated model of integrin α IIb β 3 was developed by combining the extracellular domain adopted from the crystal structure and the transmembrane and intracellular domain obtained by Nuclear Magnetic Resonace (NMR). The transmembrane domain was settled into the phosphatidylcholine (2-oleoyl-1-palmitoyl-sn-glycerol-3-phosphocholine (POPC)) lipid bilayer model. The position coordinates and velocity vectors of all atoms and water molecules around them were calculated by molecular dynamic (MD) simulation with the use of Chemistry at Harvard Macromolecular Mechanics force field in every 2 × 10 -15 seconds. Results The root-mean-square deviations (RMSDs) of atoms constructing the integrated α IIb β 3 model apparently stabilized at approximately 23 Å after 200 ns of calculation. However, minor fluctuation persisted during the entire calculation period of 650 ns. The RMSDs of both α IIb and β 3 showed similar trends before 200 ns. The RMSD of β 3 apparently stabilized approximately at 15 Å at 400 ns with persisting minor fluctuation afterward, while the structural fluctuation in α IIb persisted throughout the 650 ns calculation period. Conclusion In conclusion, the integrated model of the intracellular, transmembrane, and extracellular domain of integrin α IIb β 3 suggested persisting fluctuation even after convergence of MD calculation.

Tailoring basic and acidic properties of MgAl hydrotalcite by fluoride anions: Effect on glycerol oligomerisation

In this work, two families of catalysts based on mixed metal oxides derived from MgAl hydrotalcites were synthesized with a Mg/Al molar ratio of 3. On the one hand, in the first family, the fluoride anion was incorporated in the interlayer space by using ammonium fluoride, exploiting the “memory effect” characteristic of hydrotalcites. In the second family, fluoride anions substituted oxides anions in the layer, incorporating directly them during the precipitation of hydroxides, by using cryolite as a precursor for both fluorine and aluminium. The hydrotalcites were transformed into mixed metal oxides by thermal treatment and tested in the glycerol etherification reaction at 230 ºC, in a batch reactor at atmospheric pressure. The hydrotalcites and the corresponding mixed metal oxides were characterized by different experimental techniques, such as X-ray diffraction (XRD), elemental analysis (CHF), N2 sorption at − 196 ºC, thermogravimetric analysis (ATD-TG), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of CO2 and NH3 (CO2-TPD and NH3-DTP) and solid state nuclear magnetic resonace (ssNMR) of 19F. It was found that the mixed metal oxides prepared from hydrotalcites, where fluorine was incorporated in the synthesis step using cryolite, achieved the maximum conversion values and complete selectivity towards diglycerol. Diglycerols were the unique detected products and, in some cases, the formation of triglycerols was also detected.

A rapid method for extraction, purification and structure analysis of chondroitin sulfate from six marine tissues

Abstract This study was designed to establish a strategy for the extraction, purification, and structure analysis of chondroitin sulfate (CS) in milligram amounts. Crude acidic polysaccharides were extracted from six kinds of marine animals by enzymatic hydrolysis and hexadecylpyridinium chloride precipitation and purified by Q Sepharose Fast Flow strong anion exchange column. The purification of each crude polysaccharide was completed within 1 h. The structure of the polysaccharides, i.e. their chemical characterization, functional group, molecular weight and monosaccharide composition, were analyzed by colorimetry, nuclear magnetic resonace and high-performance liquid chromatogrpahy, respectively. All polysaccharides were identified as CS. The oligosaccharide profile produced by enzyme hydrolysis of polysaccharides was determined by strong anion-exchange high-performance liquid chromatorgraphy. This method can be widely applied to the extraction and characterization of chondroitin sulfate from unknown raw materials, screening high-quality sources of functional polysaccharides, and laying a good foundation for the following study of the structure–function relationship of polysaccharides.

Impacts of phosphorous-linked epoxidized vegetable oil on mechanical behaviors and flammability properties of silica reinforced epoxy composite

Although widely used in industrial applications, epoxy resins generally display low toughness and high flammability. The use of phosphorus compounds can improve flame-retardant capabilities along with reducing mechanical properties. Herein, the novel flame-retardant additive of phosphorous-linked epoxidized vegetable oil (P-L-EVO) was fabricated from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and epoxidized vegetable oil through a ring opening reaction before applying it as additive for an epoxy/silica system. The silica was extracted from a rice husk using a combined approach of acid treatment and thermal treatment. Successful grafting and extraction reactions were confirmed using Fourier transform infrared analysis (FTIR) and nuclear magnetic resonace (NMR). The epoxy resin-based samples were cured with diethylenetriamine (DETA) hardener at ambient conditions. The influences of additives on the mechanical properties and flame-retardant capabilities were examined via tensile strength, impact strength, critical stress intensity (KIC), a cone calorimeter, the limited oxygen index (LOI), and the UL 94 vertical test. The epoxy sample with 20 wt.% silica and 10 wt.% of P-L-EVO (S20.10) reached the LOI value of 35.89 % and a V0 rating of UL94. Moreover, this combination improved the impact strength, tensile strength, and KIC by up to 90.16 %, 20.28 %, and 73.84 %, respectively in comparison with pristine epoxy sample (S00.00). The formation of a non-thermal decomposition char layer along with a release of flame-retardant radicals was considered the novel flame-retardant mechanism.

Anion Exchange Membranes Prepared from Quaternized Polyepichlorohydrin Cross-Linked with 1-(3-aminopropyl)imidazole Grafted Poly(arylene ether ketone) for Enhancement of Toughness and Conductivity.

A novel anion exchange membrane was synthesized via crosslinking of the quaternized polyepichlorohydrin (QPECH) by 1-(3-aminopropyl) imidazole grafted poly(arylene ether ketone) (PAEK-API). While the QPECH provided an excellent ion conductive property, the rigid rod-structured PAEK-API played a reinforcing role, along with providing the high conductivity associated with the pendant API group. The chemical structure of QPECH/PAEK-API membranes was identified by 1H nuclear magnetic resonace spectroscopy. A variety of membrane properties, such as anion conductivity, water uptake, length swelling percentage, and thermal, mechanical and chemical stability, were investigated. The QPECH/PAEK-API1 membrane showed quite high hydroxide ion conductivity, from 0.022 S cm−1 (30 °C) to 0.033 S cm−1 (80 °C), and excellent mechanical strength, associated with the low water uptake of less than 40%, even at 80 °C. Such high conductivity at relatively low water uptake is attributed to the concentrated cationic groups, in a cross-linked structure, facilitating feasible ion transport. Further, the QPECH/PAEK-API membranes showed thermal stability up to 250 °C, and chemical stability for 30 days in a 4 NaOH solution, without significant loss of ion exchange capacity.

Synthesis, Characterization, Antimicrobial Evaluation of 2-Amino pyrimidine Schiff base derivative

Schiff base or imine is an analogue of a ketone or aldehyde in which the carbonyl group has been replaced by an imine or azomethine group. Schiff bases exhibits a broad range of biological activities, including antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties Imine or azomethine groups are present in various natural, natural-derived and non-natural compounds. The imine group present in such compounds has been shown to be critical to their biological activities A new compound (Z)N_(4-dimethylamino) benzylidene) pyrimidine-2-aminewas synthesized by the reaction of 2-aminopyrimidine, 4-(dimethylamino) benzaldehyde and a drop of acetic acid in the presence of ethanol respectively. The chemical structures of the synthesized compounds were characterised by using Fourier Transform Infra Red Spectroscopy (FTIR), Proton Nuclear Magnetic Resonace Spectroscopy technique (1HNMR). The synthesized compound showed mild antibacterial activity against Staphylococcus aureus and Escherichia coli.

2H16 機器分析実践プログラムでの化学・工学融合教育の試み : 核磁気共鳴装置教育を通した化学技術者の育成((07)高大院連携/(17)国際化時代における工学教育-I,口頭発表)

2H16 機器分析実践プログラムでの化学・工学融合教育の試み : 核磁気共鳴装置教育を通した化学技術者の育成((07)高大院連携/(17)国際化時代における工学教育-I,口頭発表)

Multiplatform Analytical Methodology for Metabolic Fingerprinting of Lung Tissue

Using multiplatform approaches providing wider information about the metabolome, is currently the main topic in the area of metabolomics, choosing from liquid chromatography-mass spectrometry (LC-MS), gas chromatography/mass spectrometry (GC/MS), capillary electrophoresis-mass spectrometry (CE-MS), and nuclear magnetic resonace (NMR). However, the reliability and suitability of sample treatment, data acquisition, data preprocessing, and data analysis are prerequisites for correct biological interpretation in metabolomics studies. The significance of differences between samples can only be determined when the performance characteristics of the entire method are known. This leads to performing method validation in order to assess the performance and the fitness-for-purpose of a method or analytical system for metabolomics research. The present study was designed for developing a nontargeted global fingerprinting approach of lung tissue, for the first time, applying multiple complementary analytical techniques (LC-MS, GC/MS, and CE-MS) with regards to analytical method optimization (sample treatment + analytical method), characterization, and validation as well as application to real samples. An initial solvent for homogenization has been optimized, which is usually overseen in the tissue homogenization protocol. A nontargeted fingerprinting approach was applied to a pooled sample of lung tissue using these three instruments to cover a wider range of metabolites. The linearity of the validated method for all metabolites was >0.99, with good recovery and precision in all techniques. The method has been successfully applied to lung samples from rats with sepsis compared to the control samples. Only 20 mg of tissue is required for the three analytical techniques, where only one metabolite was found in common between LC-MS and CE-MS analysis as statistically significant. This proves the importance of applying a multiplatform approach in a metabolomics study as well as for biomarker discovery.

Triterpenoids from Vernonia auriculifera Hiern exhibit antimicrobial activity

Phytochemical investigation of Vernonia auriculifera afforded farnesylamine, a sesquiterpene amine that has not been found previously in plant species, together with lupenyl acetate, oleanolic acid, β-amyrin acetate, β-amyrin, friedelanone, friedelin acetate, α-amyrin and β-sitosterol. The compounds were characterized using nuclear magnetic resonace (NMR) spectroscopy and comparison with literature values. The isolated triterpenoids exhibited moderate antibacterial activity; α and β-amyrin had minimum inhibitory concentration (MIC) of 0.25 mg/ml against Staphylococcus aureus,Bacillus subtilis, Enterococcus faecium and Staphylococcus saprophyticus while lupenyl acetate and oleanolic acid exhibited MIC of 0.25 mg/ml againstStenotrophomonas maltophilia. Sub-MIC exposure of β-amyrin acetate was effective in decreasing adhesion of S. aureus, Klebsiella pneumonia and E. faecium while oleanolic acid decreased adhesion of K. pneumonia and Pseudomonas aeruginosasignificantly at sub-MIC. These compounds show potential for synergistic coupling with antimicrobial agents to improve therapeutic efficiency, in the face of rising bacterial resistance. Key words: Vernonia auriculifera, triterpenoids, farnesylamine, antibacterial activity.

The intriguing Cyclophilin A-HIV-1 Vpr interaction: prolyl cis/trans isomerisation catalysis and specific binding

BackgroundCyclophilin A (CypA) represents a potential target for antiretroviral therapy since inhibition of CypA suppresses human immunodeficiency virus type 1 (HIV-1) replication, although the mechanism through which CypA modulates HIV-1 infectivity still remains unclear. The interaction of HIV-1 viral protein R (Vpr) with the human peptidyl prolyl isomerase CypA is known to occur in vitro and in vivo. However, the nature of the interaction of CypA with Pro-35 of N-terminal Vpr has remained undefined.ResultsCharacterization of the interactions of human CypA with N-terminal peptides of HIV-1 Vpr has been achieved using a combination of nuclear magnetic resonace (NMR) exchange spectroscopy and surface plasmon resonance spectroscopy (SPR). NMR data at atomic resolution indicate prolyl cis/trans isomerisation of the highly conserved proline residues Pro-5, -10, -14 and -35 of Vpr are catalyzed by human CypA and require only very low concentrations of the isomerase relative to that of the peptide substrates. Of the N-terminal peptides of Vpr only those containing Pro-35 bind to CypA in a biosensor assay. SPR studies of specific N-terminal peptides with decreasing numbers of residues revealed that a seven-residue motif centred at Pro-35 consisting of RHFPRIW, which under membrane-like solution conditions comprises the loop region connecting helix 1 and 2 of Vpr and the two terminal residues of helix 1, is sufficient to maintain strong specific binding.ConclusionsOnly N-terminal peptides of Vpr containing Pro-35, which appears to be vital for manifold functions of Vpr, bind to CypA in a biosensor assay. This indicates that Pro-35 is essential for a specific CypA-Vpr binding interaction, in contrast to the general prolyl cis/trans isomerisation observed for all proline residues of Vpr, which only involve transient enzyme-substrate interactions. Previously suggested models depicting CypA as a chaperone that plays a role in HIV-1 virulence are now supported by our data. In detail the SPR data of this interaction were compatible with a two-state binding interaction model that involves a conformational change during binding. This is in accord with the structural changes observed by NMR suggesting CypA catalyzes the prolyl cis/trans interconversion during binding to the RHFP35RIW motif of N-terminal Vpr.

Preparation and characterization of high char yield polybenzoxazine/polyarylacetylene blends for resin‐transfer molding

AbstractBenzoxazine precursors (BOZP), 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐ benzoxazinyl)ketone and 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐benzoxazinyl)ether were synthesized and characterized by Proton nuclear magnetic resonace (1H‐NMR) and Fourier transform infrared spectroscopy (FTIR). The polyarylacetylene (PAA) was synthesized through thermal polymerization of diethynylbenzene, and characterized by 1H‐NMR, FTIR, and Differential Scanning Calorimetry (DSC). The BOZP/PAA blends were prepared with different contents of PAA, and their viscosity was measured using NDJ‐79 rotating visometer. The curing behavior of BOZP/PAA blends was characterized by DSC. The thermal stability of cured BOZP/PAA blends was studied using Thermogravimetric Analysis, the results show char yield at 800°C was in the range of 78–84%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Mesoscopic phase separation inNaxCoO2(0.65⩽x⩽0.75)

Nuclear magnetic resonace $(\mathrm{NMR})$, $\mathrm{EPR}$ and magnetization measurements in ${\mathrm{Na}}_{x}{\mathrm{CoO}}_{2}$ for $0.65\ensuremath{\leqslant}x\ensuremath{\leqslant}0.75$ are presented. While the $\mathrm{EPR}$ signal arises from ${\mathrm{Co}}^{4+}$ magnetic moments ordering at ${T}_{\mathrm{c}}\ensuremath{\simeq}26\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, $^{59}\mathrm{Co}$ $\mathrm{NMR}$ signal originates from cobalt nuclei in metallic regions with no long range magnetic order and characterized by a generalized susceptibility typical of strongly correlated metallic systems. This phase separation in metallic and magnetic insulating regions is argued to occur below ${T}^{*}(x)$ $(220--270\phantom{\rule{0.3em}{0ex}}\mathrm{K})$. Above ${T}^{*}$ an anomalous decrease in the intensity of the $\mathrm{EPR}$ signal is observed and associated with the delocalization of the electrons which for $T<{T}^{*}$ were localized on ${\mathrm{Co}}^{4+}\phantom{\rule{0.3em}{0ex}}{d}_{{z}^{2}}$ orbitals. It is pointed out that the in-plane antiferromagnetic coupling $J⪡{T}^{*}$ cannot be the driving force for the phase separation.

Evaluation of compatibility and properties of biodegradable polyester blends

AbstractThree different biodegradable polyesters, namely, polycaprolactone (PCL), polybutylene succinate (BIONOLLE), and a copolyester of adipic acid, terephthalic acid, and 1,4‐butanediol (EASTAR) were melt‐blended using a twin‐screw extruder. The percentage composition of each of the aforementioned polymers was varied to obtain different blends, and the mechanical properties were evaluated. Selected blends showed significant improvement in tensile strength as compared with the individual polymers used to prepare the blend. The compatibility between the polymer phases was examined via Fourier transform infrared (FTIR) and nuclear magnetic resonace (NMR) spectroscopy as well as dynamic mechanical analysis. FTIR and NMR data confirmed the occurrence of hydrogen‐bonding and ester‐interchange reactions. Thermal properties and changes in crystallinity of the blends were examined with differential scanning calorimetry and X‐ray diffraction. A considerable increase in crystallinity was shown by the blend system containing BIONOLLE/PCL. The morphology of the blends was observed and correlated to the improved mechanical properties of the blend system. Results revealed an intermediate multiphase system in which a significant degree of mixing was achieved through the chemical interaction of the functional groups present, while using the twin‐screw extruder. Significant improvement in mechanical properties of some blends was observed, and information about the miscibility of these polyesters is provided. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2003–2014, 2002

The Practice on the Fatty Acid Analysis

Fatty acids are very important for not only the components of energy resources but also the characteristic and functional properties for metabolic and physiological precursors to human body. Recent years, therefore, much attention is needed to the conventional analytical techniques for accuracy and easy way of fatty acid composition by analytical instruments.In this review, the practical methods on the fatty acids analyeses are reviewed for food materials mainly by gas liquid chromatography (GLC) using the chemical conversion of fatty acids in lipid to the derivatives of esters. Furthermore, high performance liquid chromatography (HPLC) for fatty acid analysis is also reviewed and nuclear magnetic resonace (NMR) is summarized as the modern techique for nondestructive analysis especially on the n-3 family fatty acids and docosahexaenoic acid (DHA) quantification.

Synthesis and properties of styrene‐butadiene‐oxyethylene multiblock polymers

Multiblock copolymers of styrene, butadiene, and ethylene oxide were synthesized by coupling together telechelic dihydroxyl polystyrene, telechelic dihydroxyl polybutadiene, and poly(ethylene glycol), using 2,4-toluene diisocyanate as coupling agent. The copolymers were purified by extractions and characterized by infrared (IR), 1H nuclear magnetic resonace (NMR), gel permeation chromatography (GPC), transmission electron microscopy (TEM), membrane osmometry, and dynamic viscoelastometry. The multiblock copolymers are amphiphilic, exhibiting very good emulsifying properties. They possess a good phase transfer catalytic ability in Williamson reaction, and their LiClO4 complexes exhibit a conductivity above 1 × 10−4 S/cm at 35°C. © 1996 John Wiley & Sons, Inc.

Properties of a mechanically processed polymeric material

AbstractA semicrystalline polymer, polyamide, was processed using a new technique. The technique is that of mechanically grinding the material using large inputs of energy at temperatures below the glass‐transition temperature and then later reconstituting the material by applying pressure and holding at a temperature below its melting point for a period of time. This technique is normally known as mechanical alloying and only very recently has been applied to polymeric materials. The mechanical properties of strength, ductility, toughness, and hardness of polyamide material processed by this technique are investigated and compared with those of polyamide material processed by other techniques. The results indicate that altered mechanical properties occur with specific enhancements. This means that useful structural components can be made from polymers using this processing technique. The analysis of x‐ray diffraction, nuclear magnetic resonace, scanning electron and optical microscopy suggests that this process has resulted in considerable alteration of both crystal structure and microstructure of this polymeric material. © 1994 John Wiley & Sons, Inc.

4820988 Magnetic gradient coil set for nuclear magnetic resonace system having substantially different coil-patient spacings

In a gradient coil set for a magnetic resonance system, the y gradient coils are located substantially closer to the patient than are the x and z gradient coils. As a result, one may design the y gradient coils to produce a stronger y gradient, to have reduced inductance or otherwise better tailor the magnetic/electrical properties of the gradient coil set for MRI imaging sequences. In the exemplary embodiment, at least portions of the y gradient coils have a first spacing from the z-axis while the x and z gradient coils have a second substantially larger spacing from the z-axis. Furthermore, while the x and z gradient coils are centered about the z-axis in the patient access space, alternate sides of the y gradient coil set are centered about respectively off-set centers vertically displaced from the z-axis center of the patient access area. The result is a substantially rectangular or elliptical patient access opening with horizontal dimensions defined by the x, z coils sets and vertical dimensions defined by the y coil set.

2] Two-dimensional nuclear magnetic resonance spectroscopy of proteins: An overview

Publisher Summary This chapter discusses the two dimensional nuclear magnetic resonace spectroscopy of protein. NMR spectroscopy is the leading technique for obtaining structural and dynamic information at the atomic level about proteins in solution. It provides an efficient method for measuring dynamic, kinetic, and thermodynamic parameters (e.g., correlation times, order parameters, hydrogen exchange rates, and pKa values) in peptides and small proteins. NMR is the only serious competitor to single-crystal diffraction analysis for modeling three-dimensional structure of small proteins. NMR analysis is complementary to crystallography in providing a means of determining whether the protein structure is the same in solution as in the solid state. The protein NMR field appears to be entering a new phase. Available and newly emerging 2D NMR methods make it possible to resolve and assign signals from a large number of 1 H, 13 C, and 15 N nuclei in proteins of M r - 2 relaxation will prevent a dramatic increase in this limit.

Glass transition temperature and heat capacity of heterotacticlike PMMA

AbstractThe glass transition temperature and heat capacity have been determined by differential scanning calorimetry on samples of heterotacticlike monodisperse poly(methyl methacrylate) (PMMA). The nuclear magnetic resonace spectra of these samples reveal that they contain a larger percentage of mr triads (ca. 51%) than atactic polymers and that their microstructure may be predominantly stereoregular because of an abundance of mrrr sequences. We combine our Tg values with data from the literature for PMMAs of other tacticities, in order to analyze the correlation of Tg with tacticity. In this analysis, we consider PMMA as a steric copolymer formed by mm, mr, and rr triads.

Structural Studies of Chicken Erythrocyte Histone H5

Spectroscopic studies (nuclear magnetic resonance, circular dichroism and infrared) have been carried out on chicken erythrocyte histone H5 and on three peptides cleaved therefrom: 1-31, 32-197 and 58-197. It is shown that at ionic strengths above o.1M part of the H5 molecule takes up a globular conformation containing 14% alpha helix but no beta sheet structure. Several details of the circular dichroism and nuclear magnetic resonace spectra indicate that the globular region is located in the N-terminal half of the molecule and this proposal is supported by the observation that the peptide 32-197 is largely incapable of folding and the peptide 59-197 is completely incapable of folding. Structural similarities and differences between histone H5 and histone H1 are discussed.