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  • Liposome
  • NMR
  • Springer  (33)
  • American Meteorological Society
  • Elsevier
  • MDPI Publishing
  • 2000-2004  (33)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    The effect of flexible lattice aluminium in zeolite beta during the nitration of toluene with nitric acid and acetic anhydride (2000)
    Springer
    Catalysis letters 70 (2000), S. 61-65 
    Details
    ISSN: 1572-879X
    Keywords: flexible lattice aluminium ; zeolite beta ; nitration ; regio‐control ; para‐selectivity ; toluene ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The nitration of toluene with nitric acid and acetic anhydride using zeolite H‐beta as catalyst was studied with multi‐nuclear solid‐state NMR spectroscopy in order to investigate the causes for the observed enhanced para‐selectivity. The reversible transformation of framework aluminium from a tetrahedral into an octahedral environment was observed by 27Al NMR upon interaction of the zeolite with the different components of the nitrating system. The octahedral co‐ordination complex between lattice aluminium and acetylnitrate might explain the surface‐catalysed para‐selective nitration reaction and suggests that the lattice flexibility plays an important role in determining the regio‐selectivity of the nitration catalysed by zeolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019015216483
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  • 2
    Electronic Resource
    Electronic Resource
    A comparative CP/MAS 13C-NMR study of cellulose structure in spruce wood and kraft pulp (2000)
    Springer
    Cellulose 7 (2000), S. 35-55 
    Details
    ISSN: 1572-882X
    Keywords: cellulose ; hemicellulose ; kraft pulp ; NMR ; spruce wood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract CP/MAS 13C-NMR spectroscopy in combination with spectral fitting was used to study the supermolecular structure of the cellulose fibril in spruce wood and spruce kraft pulp. During pulping, structures contributing to inaccessible surfaces in the wood cellulose are converted to the cellulose Iβ allomorph, that is, the degree of order is increased. This increase is also accompanied by a conversion of cellulose Iα to cellulose Iβ. Cellulose from wood composed of different cell types, that is, compression wood, juvenile wood, earlywood, latewood and normal wood exhibited a similar supermolecular structure. Assignments were made for signals from hemicellulose which contribute significantly to the spectral C-4 region (80–86 ppm) in kraft pulp spectra but substantially less to the corresponding region in wood spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009236932134
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  • 3
    Electronic Resource
    Electronic Resource
    A 29Si MAS-NMR study of Cd7[Ge6Si]O21 pyroxmangite (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 713-718 
    Details
    ISSN: 1432-2021
    Keywords: Key words Cd-pyroxmangite ; NMR ; Pyroxenoids ; Ordering ; Superperiods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Synthetic (SiGe)-pyroxenoids are often observed to have superperiods. Whether or not these superperiods grow in connection with Si-Ge ordering is a fundamental question. The size difference between Ge and Si tetrahedra leads to CdGeO3 having the pyroxmangite structure, whereas CdSiO3 has the wollastonite structure. Consequently, considerable strain is expected for a pyroxenoid with a disordered Ge-Si distribution. A 29Si MAS-NMR study of a Cd-pyroxmangite of nominal composition Cd7[Ge6Si]O7 points to considerable Si clustering, probably as GeSiSiSiGe triples corresponding to the wollastonite-like units of the siebener chain. It is proposed that such ordering relieves strain within the tetrahedral chain. Residual strain is also relieved by insertion of an extra pair of GeO4 tetrahedra into the pyroxene-like component of the siebener-chain units, leading to single neuner-chain units which terminate the superperiods. This growth pattern is cyclic. The presence of several types of superperiod may reflect similar energetics for different Ge-Si-ordering patterns within the siebener chains. Ordering of Si-rich unit cells and of unit cells having no Si is proposed as the reason for the occurrence of the superperiods in Cd-pyroxmangite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000115
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  • 4
    Electronic Resource
    Electronic Resource
    NMR Structure Determination and Structure-Based Functional Characterization of Conserved Hypothetical Protein MTH1175 from Methanobacterium thermoautotrophicum (2000)
    Springer
    Journal of structural and functional genomics 1 (2000), S. 15-25 
    Details
    ISSN: 1570-0267
    Keywords: structural genomics ; RNase H ; NMR ; methanobacterium thermoautotrophicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The solution structure of MTH1175, a 124-residue protein from the archaeon Methanobacterium thermoautotrophicum has been determined by NMR spectroscopy. MTH1175 is part of a family of conserved hypothetical proteins (COG1433) with unknown functions which contains multiple paralogs from all complete archaeal genomes and the archaeal gene-rich bacterium Thermotoga maritima. Sequence similarity indicates this protein family may be related to the nitrogen fixation proteins NifB and NifX. MTH1175 adopts an α/β topology with a single mixed β-sheet, and contains two flexible loops and an unstructured C-terminal tail. The fold resembles that of Ribonuclease H and similar proteins, but differs from these in several respects, and is not likely to have a nuclease activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011348803324
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  • 5
    Electronic Resource
    Electronic Resource
    Structure and Morphology of a Polyether/Polyacrylate Semi-interpenetrating Polymer Network (2000)
    Springer
    Journal of thermal analysis and calorimetry 59 (2000), S. 83-92 
    Details
    ISSN: 1572-8943
    Keywords: cationic and photoinitiated polymerization ; DSC ; interfacial mixing ; interpenetrating polymer network (IPN) ; glass transition temperature ; NMR ; quantitative thermal analysis of phases ; reactive epoxy and acrylate systems ; Tg broadening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this study NMR and DSC are used to probe the structure, thermal characteristics and morphology of a network formed from a diepoxide/acrylate system. Separate chemistries are employed to polymerize the diepoxide and acrylate components. The cationic polymerization of the diepoxide exhibits excellent selectivity in producing a crosslinked polyether network without affecting the acrylate monomer. Subsequent photoinitiated free-radical polymerization of the acrylate produces a phase separated, semi-interpenetrating polymer network (SIPN).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010123610324
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  • 6
    Electronic Resource
    Electronic Resource
    [13C]Dynamic NMR and Molecular Modeling of 2,4-Bis(N-Pyrrolidinyl)-6-chloro-s-triazine (2000)
    Springer
    Structural chemistry 11 (2000), S. 303-306 
    Details
    ISSN: 1572-9001
    Keywords: NMR ; [13C]NMR ; 2,4-bis(N-pyrrolidinyl)6-chloro-s-triazine ; variable temperature ; molecular modeling ; rotational barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The room temperature [13C]NMR spectrum of 2,4-bis(N-pyrrolidinyl)-6-chloro-s-triazine shows doubled signals for the pyrrolidine rings, which suggests restricted rotation about the Ar-C—N bond. The rotational barrier around this bond was determined by [13C]dynamic NMR (DNMR) spectra run at different increasing temperatures and also by the PM3 Hamiltonian contained in the MOPAC package. The values thus obtained, 16.6 and 13.6 kcal mol−1, respectively, are in good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009238326751
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  • 7
    Electronic Resource
    Electronic Resource
    An NMR Study of MeTMS Based Coatings Filled with Colloidal Silica (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 131-135 
    Details
    ISSN: 1573-4846
    Keywords: coatings ; colloids ; NMR ; organosilanes ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Coatings were prepared by mixing MeTMS and an aqueous colloidal silica. Mixing of an MeTMS hydrolysis mixture with the aqueous colloidal silica is only possible, without flocculation of the colloidal silica particles, within a certain time window. 29Si NMR was used to follow the hydrolysis/condensation reactions of MeTMS, whereas 1H NMR was used to monitor the reaction of the MeTMS monomers and oligomers with the silica surface in the coating liquid. The reaction of MeTMS with the surface of the SiO2 particles is determined by the oligomer size. Typical SiO2 surface coverage is less than 3 molecules/nm2 (approximately one monolayer). Large MeTMS oligomers and/or cyclic species do not react with the SiO2 surface. These species are probably too apolar to react or absorb at the SiO2 surface. Flocculation of the aqueous colloidal silica occurs due to the low polarity of the hydrolysis mixture. The water content and the degree of condensation of the MeTMS determine the width of the time window.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008795113990
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  • 8
    Electronic Resource
    Electronic Resource
    Non-Hydrolytic Routes for the Synthesis of NASICON (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 463-467 
    Details
    ISSN: 1573-4846
    Keywords: NASICON ; NMR ; non-hydrolytic synthesis ; precursor chemistry ; solid electrolyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The study of non-hydrolytic reactions for the synthesis of NASICON is reported. Different procedures have been considered, changing the precursors and their addition order, and varying the reaction solvent; dichloromethane, acetonitrile and tetrahydrofuran (THF). The most promising results in terms of homogeneous reactivity were obtained using PO(On-C4H9)3, Zr(Ot-C4H9)4, SiCl4 and Na(Ot-C4H9) in acetonitrile. The reactions were followed using heteronuclear Nuclear Magnetic Resonance (NMR) spectroscopy (13C, 31P). NASICON powders were prepared by the thermal decomposition of the gels between 900 and 1200°C. The powders were analyzed by XRD to check the formation of the NASICON phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008707815750
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  • 9
    Electronic Resource
    Electronic Resource
    Comparative Study of Structure of Silica Gels from Different Sources (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 495-499 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; silicas ; biology ; X-ray diffraction ; IR ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The medium-range-network structure of silicas from different sources was comparatively examined by X-ray diffraction, IR and NMR analyses. Silica gels made through the conventional sol-gel route were found to have a different structure from silica glass, and considered to be composed of 4-fold siloxane ring units, irrespective of preparation conditions. Amorphous silicas in rice-hulls and bamboo leaves showed structure data close to silica glass, being suggested to consist mainly of 6-fold siloxane ring units. The modified sol-gel method, in which siloxane oligomers containing cyclic siloxane tetramers may have been ring-opened and polymerized under the catalytic reaction of NaOH or NH4F in the water-free solution, provided the silica gel of which structure was very similar to silica glass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008720118475
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  • 10
    Electronic Resource
    Electronic Resource
    Low Temperature Sol-Gel Preparation of β-Al2TiO5 Thin Films: Spectroscopic Analysis of the Precursors (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 577-580 
    Details
    ISSN: 1573-4846
    Keywords: aluminum titanate ; NMR ; MS ; thin films ; precursor chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two sol-gel syntheses allowed the preparation of β-Al2TiO5 thin films on silicon substrates at 700°C, reacting aluminum and titanium alkoxides with and without acetylacetone as a chelating agent. Nuclear magnetic resonance (NMR) and mass spectra of the sols allowed identification of the intermediate species formed and to show the formation of an Al-Ti containing polymer establishing that the synthesis without acetylacetone leads to the most extensive polymerization. The formation of β-Al2TiO5 at low temperatures is attributed to diffusion-limited crystallization process, which takes place in the conditions of high homogeneity at molecular level reached in the sol-gel synthesis. The crystallization of the films was studied as a function of the firing time and temperature and confirmed that β-Al2TiO5 with better thermal stability was obtained with the synthesis without chelating agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008705109815
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  • 11
    Electronic Resource
    Electronic Resource
    The Structure of Hybrid Gels by Drift and NMR Spectroscopies (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 403-407 
    Details
    ISSN: 1573-4846
    Keywords: hybrid gels ; silica ; polytetrahydrofuran ; DRIFTS ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hybrid inorganic-organic gels have been prepared by the sol-gel process using tetraethoxysilane (TEOS) as precursor, mixed with a low concentration of polytetrahydrofuran (PTHF), under acid catalysis. The hybrid xerogels were characterized by DRIFTS and Solid State 1H, 13C and 29Si NMR. The DRIFT spectra indicate that the polymer is responsible for decreasing the number of free silanol groups in comparison to pure silica. Solid-state NMR spectra reveal the types of silicate structures formed and the conditions for establishing chemical bonds between the two phases, which are responsible for the silica network flexibility. We have concluded that it is possible to design a hybrid gel with tailored properties, even at very low polymer concentration, by selecting the appropriate preparation route.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008783010298
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  • 12
    Electronic Resource
    Electronic Resource
    The Effect of Nanoscaled Metal Oxide Sols on the Structure and Properties of Glycidoxypropyltrimethoxysilane Derived Sols and Gels (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 305-309 
    Details
    ISSN: 1573-4846
    Keywords: epoxide ; ring-opening ; condensation ; NMR ; hardness ; nanoparticles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Glycidoxypropyltrimethoxysilane (GPTS) is frequently used as precursor for the preparation of sol-gel derived nanoscaled hybrid polymers. The influence of nanoscaled metal oxide sols of silica, boehmite, zirconia and ceria on reactions of GPTS in ethanolic hydrolysates and in corresponding gels (epoxide ring-opening, condensation degree) was examined by liquid- and solid-state 13C and 29Si NMR with regard to a better correlation between structure and material properties. Generally, a higher condensation degree of RSi(O0.5)3 units of GPTS is found after addition of metal oxide sols compared to GPTS without additives. The metal oxide sols (10 mole% series) cause an epoxide ring-opening up to 20% in GPTS hydrolysates after 24 h. A nearly complete ring opening was found in the boehmite and silica containing hybrid gels whereas gels containing ceria and other types of silica only show a low degree of ring-opening. The results show an accelerated ring-opening with increasing content of AlO/OH-species in silica sols. 13C NMR studies reveal that the epoxide ring-opening does not completely lead to polyether structures but to considerable amounts (up to 40%) of ethylether groups which can influence the material properties (hardness).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008777414416
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  • 13
    Electronic Resource
    Electronic Resource
    Conformational Studies of a Melittin—Inhibitor Complex (2000)
    Springer
    The protein journal 19 (2000), S. 529-534 
    Details
    ISSN: 1573-4943
    Keywords: Melittin ; inhibitor ; NMR ; peptide ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The conformation of a melittin—inhibitor complex was studied by solution NMR, solid-state NMR, and circular dichroism. In solution, binding was studied by titrating inhibitor against melittin in dimethyl sulfoxide, methanol, aqueous buffer, and dodecylphosphocholine micelles. The change in chemical shift of Trp19 resonances and the formation of a precipitate at 1:1 molar ratio indicated that the inhibitor was bound to melittin. Solid-state NMR also showed a change in chemical shift of two labeled carbons of melittin near Pro14 and a change in 1H T 1 relaxation times when complexed with inhibitor. Rotational resonance experiments of melittin labeled in the proline region indicated a change in conformation for melittin complexed with inhibitor. This observation was also supported by circular dichroism measurements, indicating a reduction in α-helical structure for increasing ratios of inhibitor bound to melittin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026561701338
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  • 14
    Electronic Resource
    Electronic Resource
    Temperature, pH, and Solvent Isotope Effects on Cytochrome c Peroxidase Mutant N82A Studied by Proton NMR (2000)
    Springer
    The protein journal 19 (2000), S. 535-542 
    Details
    ISSN: 1573-4943
    Keywords: Cytochrome c peroxidase ; CcP ; NMR ; A82CcP mutant ; solvent isotope effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The mutant of baker's yeast cytochrome c peroxidase-CN with Ala82 in place of Asn82, [N82A]CcPCN, exhibits a complex solution behavior featuring dynamic interconversion among three enzyme forms that so far have only been detected by NMR spectroscopy. Proton NMR studies of [N82A]CcPCN reveal resonances from each of the three enzyme forms and show that the interconversion among forms is controlled by the pH, temperature, and isotope composition (H2O vs. D2O) of the buffer solution. No evidence for a key hydrogen bond between His52 and heme-coordinated cyanide is found in any of the enzyme forms, indicating that disruption of the extensive distal hydrogen bonding network is the source of this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026513818176
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  • 15
    Electronic Resource
    Electronic Resource
    Analysis of the structure of lignin-carbohydrate complexes by the specific13C tracer method (2000)
    Springer
    Journal of wood science 46 (2000), S. 130-136 
    Details
    ISSN: 1611-4663
    Keywords: Lignin-carbohydrate complexes ; NMR ; 13C tracer ; Coniferin ; Ketal linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the present study the specifically13C-enriched lignin precursors of biosynthesis (i.e., coniferin-[side chainα−13C], coniferin-[side chain-β−13C] and coniferin-[side chain-γ−13C]) were synthesized and administered exogeneously to ginkgo shoots (Ginkgo biloba L.) to obtain13C-enriched lignin-carbohydrate complexes (LCCs). The specifically13C-enriched LCCs were isolated from the newly formed xylem of ginkgo shoots administered with the13C-enriched precursors and degraded by enzymes. Lignin-rich fractions, so called enzyme-degraded LCCs (EDLCCs), were obtained. By determining their13C-NMR spectra, information related to the chemical structure of lignin building units and linkages between phenylpropane units of lignin and carbohydrates were obtained. It was found that these precursors were incorporated in natural lignin successfully. Three lignin-carbohydrates linkages (i.e., ether type, ester type, ketal type) were found at the C α -position of the side chain of phenylpropane units in ginkgo LCC. No lignin-carbohydrate bond at the Cβ- or Cγ-position of the lignin side chain was observed in the13C-NMR spectra of the13C-enriched LCCs. This fact indicates that a specific13C tracer technique can be useful in NMR study of the chemical structure of LCCs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00777359
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  • 16
    Electronic Resource
    Electronic Resource
    Modeling ganglioside headgroups by conformational analysis and molecular dynamics (2000)
    Springer
    Glycoconjugate journal 17 (2000), S. 283-299 
    Details
    ISSN: 1573-4986
    Keywords: ganglioside conformation ; NMR ; molecular mechanics ; molecular dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The conformations and dynamics of gangliosides GM1, GM2, 6′-GM2 and GM4 have been studied by computational means, and the results compared to NMR data. Unconstrained conformational searches were run using the AMBER* force field augmented by MNDO derived parameters for the Neu5Ac anomeric torsion, the GB/SA water solvation model, and the MC/EM alogorithm; extended (10–12[emsp4 ]ns) dynamic simulations in GB/SA water were performed with the MC/SD protocol, and the stored structures were minimized. The overall mobility of the Neu5Acα2,3Gal linkage and the position of its minimum energy conformation have been shown to depend mainly on the presence or the absence of a GalNAc residue at the adjacent position. The best quantitative agreement with the available NOE data was achieved after minimization of the structures stored during the MC/SD dynamic runs. The latter protocol appears to reproduce satisfactorily the available experimental data, and can be used with confidence to build three-dimensional models of ganglioside headgroups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007161319700
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  • 17
    Electronic Resource
    Electronic Resource
    Glycosylations versus conformational preferences of cancer associated mucin core (2000)
    Springer
    Glycoconjugate journal 17 (2000), S. 835-848 
    Details
    ISSN: 1573-4986
    Keywords: cancer vaccine ; glycopeptide ; MUC-1 ; immunotherapy ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Synthetic oligosaccharide vaccines based on core STn (sialyl α2-6 GalNAc) carbohydrate epitopes are being evaluated by a number of biopharmaceutical firms as potential immunotherapeutics in the treatment of mucin-expressing adenocarcinomas. The STn carbohydrate epitopes exist as discontinuous clusters, O-linked to proximal serine and threonine residues within the mucin sequence. In an effort to probe the structure and dynamics of STn carbohydrate clusters as they may exist on the cancer-associated mucin, we have used NMR spectroscopy and MD simulations to study the effect of O-glycosylation of adjacent serine residues in a repeating (Ser)n sequence. Three model peptides/glyco-peptides were studied: a serine trimer containing no carbohydrate groups ((Ser)3 trimer); a serine trimer containing three Tn (GalNAc) carbohydrates α-linked to the hydroxyls of adjacent serine sidechains ((Ser.Tn)3 trimer); and a serine trimer containing three STn carbohydrates α-linked to the hydroxyls of adjacent serine sidechains ((Ser.STn)3 trimer). Our results demonstrate that clustering of carbohydrates shifts the conformational equilibrium of the underlying peptide backbone into a more extended and rigid state, an arrangement that could function to optimally present the clustered carbohydrate antigen to the immune system. Steric effects appear to drive these changes since an increase in the size of the attached carbohydrate (STn versus Tn) is accompanied by a stronger shift in the equilibrium toward the extended state. In addition, NMR evidence points to the formation of hydrogen bonds between the peptide backbone NH protons and the proximal GalNAc groups in the (Ser.Tn)3 and (Ser.STn)3 trimers. The putative peptide-sugar hydrogen bonds may also play a role in influencing the conformation of the underlying peptide backbone, as well as the orientation of the O-linked carbohydrate. The significance of these results will be discussed within the framework of developing clustered STn-based vaccines, capable of targeting the clustered STn epitopes on the cancer-associated mucin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010909011496
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  • 18
    Electronic Resource
    Electronic Resource
    Energy metabolism and re-establishment of intercellularadhesion complexes of gel entrapped hepatocytes (2000)
    Springer
    Cytotechnology 32 (2000), S. 219-228 
    Details
    ISSN: 1573-0778
    Keywords: alginate ; bioreactor ; energy metabolism ; hepatocytes ; microscopy ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We studied the effect of continuous medium flow on the viabilityand structural organization of hepatocytes high density entrapped inalginate gel beads in the first few hours after isolation.The metabolic energy status of the entrapped cells, monitored invivo by 31P NMR spectroscopy, was stable during theexperimental time and a physiological redox ratio was reachedafter the first three hours of culture. The morphologicalanalysis revealed that the entrapped hepatocytes placed in a fixed-bed bioreactor under continuous flow showed a polyhedricalshape with numerous microvilli on cell surface and reconstitutedtight junctions as well as bile canalicular structures, closelyresembling those present in the liver.These results suggest that continuous flow allows the culture ofhepatocytes at very high cell density within a matrix withoutloss of viability and accelerates cellular tissue reconstructionat very short times after isolation. This type of culture couldrepresent a very useful model for physiological andtoxicological studies as well as a promising approach toward thedevelopment of a bioartificial hybrid support device in acuteliver failure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008134005529
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  • 19
    Electronic Resource
    Electronic Resource
    Structural studies of the glycopeptides of B-chain of cinnamomin – a type II ribosome-inactivating protein by nuclear magnetic resonance (2000)
    Springer
    Glycoconjugate journal 17 (2000), S. 749-759 
    Details
    ISSN: 1573-4986
    Keywords: cinnamomin ; glycopeptides ; NMR ; primary structure ; ribosome-inactivating protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cinnamomin is a plant type II ribosome-inactivating protein (RIP) isolated from the seeds of Cinnamomum camphora. It consists of two nonidentical polypeptide chains (A- and B-chain) held together through one disulfide linkage. Its A- and B-chain contain 0.3% and 3.9% sugars respectively. The B-chain of cinnamomin was digested by pronase E and then the liberated glycopeptides were separated from non-glycopeptides by gel filtration chromatography on a Bio-Gel P-4 column. Three crude glycopeptides were obtained by continuing chromatography over anion-exchange resin (AG1-X2) in the buffer of 2% pyridine-acetic acid (pH 8.3) with a polygradient elution system. Through further purification by the gel filtration chromatography and HPLC, three major glycopeptides, GP1, GP2 and GP3 were obtained. Mainly by two-dimensional Nuclear Magnetic Resonance (NMR) including TOCSY, DQF-COSY, NOESY, HMQC and HMBC, their primary structures were analyzed as: Manα1,3Manα1,6(Manα1,3)(Xylβ1,2)Manβ1,4GlcNAcβ1,4GlcNAcβ1-(Gly-)Asn-Asn-Thr(GP1), Manα1,6(Manα1,3)(Xylβ1,2)Manβ1,4GlcNAcβ1,4(Fucα1,3)GlcNAcβ1-Asn-Ala-Thr(GP2),Manα1,6(Manα1,3)Manα1,6(Manα1,2 Manα1,3)Manβ1,4GlcNAcβ1,4GlcNAcβ1-(Ala-)Asn-Gly-Thr(GP3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010957007038
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    Electronic Resource
    Alkaloids of Peganum harmala (2000)
    Springer
    Chemistry of natural compounds 36 (2000), S. 602-605 
    Details
    ISSN: 1573-8388
    Keywords: Peganum harmala ; alkaloid ; dipegine ; dipeginol ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dipegine (1) and dipeginol (2) were isolated fromPeganum harmala.The structures of these alkaloids were established by mass and IR spectra
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017524027513
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    The Oligomeric Subunit c Rotor in the Fo Sector of ATP Synthase: Unresolved Questions in Our Understanding of Function (2000)
    Springer
    Journal of bioenergetics and biomembranes 32 (2000), S. 433-439 
    Details
    ISSN: 1573-6881
    Keywords: FoF1-ATP synthase ; Fo rotary motor ; subunit c ; subunit a ; transmembrane helices ; NMR ; cross linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract We have proposed a model for the oligomeric c-rotor of the Fo sector of ATP synthase and its interaction with subunit a during H+-transport driven rotation. The model is based upon the solution structure of monomeric subunit c, determined by NMR, and an extensive series of cross-linking distance constraints between c subunits and between subunits c and a. To explain the complete set of cross-linking data, we have suggested that the second transmembrane helix rotates during its interaction with subunit a in the course of the H+-translocation cycle. The H+-transport coupled rotation of this helix is proposed to drive the stepwise movement of the c-oligomeric rotor. The model is testable and provides a useful framework for addressing questions raised by other experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005604722178
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    Fluorometric and NMR Studies of the Naproxen–Cyclodextrin Inclusion Complexes in Aqueous Solutions (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 383-394 
    Details
    ISSN: 1573-1111
    Keywords: naproxen ; cyclodextrins ; complexation ; association constants ; fluorescence ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Inclusion complexation processesinvolving four cyclodextrins and naproxen have beenstudied for the protonated and unprotonated forms ofthe guest molecule. The association constants havebeen evaluated from changes in the fluorescenceintensity of naproxen following addition of acyclodextrin to an aqueous naproxen solution. 1HNMR NOESY and ROESY spectra have shown that twoorientations of the guest molecule relative toβ-cyclodextrin are possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008114815223
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    Electronic Resource
    Electronic Resource
    Transfection of Lymantria dispar insect cell lines (2000)
    Springer
    Methods in cell science 22 (2000), S. 257-263 
    Details
    ISSN: 1573-0603
    Keywords: In vitro ; Liposome ; Lymantria dispar ; Transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lepidopteran cell lines derived from the gypsy moth, Lymantria dispar, have not been widely used in protein expression studies or systems because they are weakly adherent, have specific growth requirements and characteristics, and are generally difficult to transfect. Using lipid-mediated transfection of a reporter plasmid, we modify the standard method for transfection of L. dispar-derived embryonic cell lines IPLB-LdEp and -LdEIta, obtaining transfection efficiencies of 34% and 30%, respectively, as determined by image analysis assays. Using the standard lipid-mediated method, we obtain transfection efficiencies for L. dispar-derived cell line IPLB-Ld652Y of at least 40% with high mean expression levels, indicating the IPLB-Ld652Y cell line may be a superior choice for expression studies or systems requiring L. dispar-derived cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017533119177
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    Thermal Behavior of Dispersed Vanadium Dioxide Particles in Polyethylene Glycol Matrix Containing Tetraethylammonium Bromide (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 473-478 
    Details
    ISSN: 1572-8943
    Keywords: metal-semiconductor phase transitions ; NMR ; polyethylene glycol matrix ; vanadiumdioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study has been made on samples of dispersed vanadium dioxide (VO2) in a matrix of polyethylene glycol (PEG) doped with a quaternary ammonium salt (QAS), namely tetraethylammonium bromide. It has been established that under the influence of the dopant the heating of a sample up to the temperature of the metal-semiconductor phase transition (MSPT) results in a phase in homogeneity of the sample. On the basis of the results of this study it is possible to conclude that small concentrations of QAS in a PEG matrix can exert a strong effect on the electronic structure of dispersed VO2 particles. This is accompanied by the appearance of phase heterogeneity of VO2 which manifests itself in the fact that - with the onset of MSPT with increasing temperature - one portion of the substance passes into the metallic state, and the other remains in the semiconductive state.
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    URL: http://dx.doi.org/10.1023/A:1010166903988
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    Electronic Resource
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    The primary electron acceptor of green sulfur bacteria, bacteriochlorophyll 663, is chlorophyll a esterified with Δ 2,6-phytadienol (2000)
    Springer
    Photosynthesis research 63 (2000), S. 269-280 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophyll a epimer ; bacteriochlorophyll 663 ; chlorophyll a ; green sulfur bacteria ; FAB-mass ; NMR ; phytadienol ; primary electron acceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The primary electron acceptor of green sulfur bacteria, bacteriochlorophyll (BChl) 663, was isolated at high purity by an improved purification procedure from a crude reaction center complex, and the molecular structure was determined by fast atom bombardment mass spectroscopy (FAB-mass), 1H- and 13C-NMR spectrometry, double quantum filtered correlation spectroscopy (DQF-COSY), heteronuclear multiple-quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC) spectral measurements. BChl 663 was 2.0 mass units smaller than plant Chl a. The NMR spectra showed that the macrocycle was identical to that of Chl a. In the esterifying alcohol, a singlet P71 signal was observed at the high-field side of the singlet P31 signal in BChl 663, while a doublet peak of P71 overlapped that of P111 in Chl a. A signal of P7-proton, seen in Chl a, was lacking, and the P6-proton appeared as a triplet signal near the triplet P2-proton signal in BChl 663. These results indicate the presence in BChl 663 of a C=C double bond between P6 and P7 in addition to that between P2 and P3. The structure of BChl 663 was hence concluded to be Chl a esterified with 2,6-phytadienol instead of phytol. In addition to BChl 663, two molecules of the 132-epimer of BChl a, BChl a′, were found to be present per reaction center, which may constitute the primary electron donor.
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    URL: http://dx.doi.org/10.1023/A:1006480629059
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    Electronic Resource
    Electronic Resource
    Volume dependence of NMR of ordered correlated electron systems (2000)
    Springer
    Hyperfine interactions 128 (2000), S. 167-181 
    Details
    ISSN: 1572-9540
    Keywords: NMR ; high pressure ; phase transitions ; magnetic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The importance of NMR high pressure studies of ordered magnetic materials for the understanding of the ground and excited states of magnetic conductors is discussed with examples from recent work on the manganese perovskites and the rare earth compounds SmMn2Ge2 and CeIn3. A brief discussion is given of the difference between true pressure experiments and the “chemical pressure” introduced by changing the composition of a material.
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    URL: http://dx.doi.org/10.1023/A:1012631515382
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    Study of single crystal surfaces with polarized 8Li (2000)
    Springer
    Hyperfine interactions 127 (2000), S. 463-468 
    Details
    ISSN: 1572-9540
    Keywords: NMR ; surfaces ; Si(1 1 1) (7×7) ; Ru(0 0 1) ; Li adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract NMR experiments on 8Li adsorbed on semiconductor and metallic surfaces are described (Si(1 1 1)−(7×7) and Ru(0 0 1)). They yield detailed information on LDOS (EF), the local density of states at the nucleus and at Fermi energy.
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    URL: http://dx.doi.org/10.1023/A:1012678003570
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    An apparatus for NMR of laser polarized 129Xe on single crystal surfaces (2000)
    Springer
    Hyperfine interactions 127 (2000), S. 469-474 
    Details
    ISSN: 1572-9540
    Keywords: NMR ; single crystal surfaces ; optical pumping of Rb ; hyperpolarized 129Xe ; laser polarized 129Xe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Due to a lack of at least 2 orders of magnitude in the amount of sample nuclei, single crystal surfaces are out of reach for conventional NMR measurements. Our aim is to prove that highly polarized 129Xe provides a technique to overcome this restriction. Therefore an apparatus for polarizing 129Xe up to 0.7 by spin transfer from optically pumped Rb has been designed as well as an NMR spectrometer in combination with a UHV chamber with sample cleaning, cooling and characterization abilities and a special manifold of glass stopcocks with a liquid nitrogen cooled trap for dosing nitrogen free polarized Xe into the chamber onto the surface.
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    URL: http://dx.doi.org/10.1023/A:1012630120408
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    Anisotropy of the Hyperfine Field on 57Fe in Pure and Substituted Yttrium Iron Garnet (2000)
    Springer
    Hyperfine interactions 131 (2000), S. 3-19 
    Details
    ISSN: 1572-9540
    Keywords: NMR ; hyperfine field ; ferrites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using NMR, anisotropy of the hyperfine field on 57Fe nuclei was measured in Y3Fe5O12 with nonmagnetic, trivalent substitutions on d (Ga3+) and a (Y3+ - yttrium antisite defect) sites which are occupied by ferric ions in a pure, stoichiometric system. The measurements were performed by the spin-echo method at liquid helium temperature. Thorough analysis of the hyperfine field anisotropy on the 57Fe nuclei in an ideal environment and in an environment where one of Fe3+ nearest cation neighbours is replaced by the nonmagnetic impurity is given. When the Fe3+ on which the NMR is measured is on the a site and the impurity is Ga3+(d), the results may be interpreted in terms of the superposition model. On the other hand, the results for Fe3+ on the d site and Y3+(a) are in clear disagreement with the predictions of this model.
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    URL: http://dx.doi.org/10.1023/A:1011014920070
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    In Vivo Gene Transfer to the Mouse Nasal Cavity Mucosa Using a Stable Cationic Lipid Emulsion (2000)
    Springer
    Molecules and cells 10 (2000), S. 142-147 
    Details
    ISSN: 0219-1032
    Keywords: DNA Delivery ; Heparin ; In Vivo Transfection ; Liposome ; Nasal Mucosa ; Physicochemical Property
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We evaluate a new cationic emulsion as a mucosal gene carrier and elucidate the relationship between the transfection efficiency and the stability of the carrier/DNA complex. A cationic lipid emulsion was formulated with soybean oil and 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as major components and was used to transfer genes to the epithelial cells of the mouse nasal cavity via intranasal instillation. Correlation between the transfection efficiency and the stability of the carrier/DNA complex was investigated by measuring the carrier size changes and by observing the degree of DNA protection against DNase I digestion in the presence of heparin. The cationic emulsion showed at least 3 times better transfection activity than the liposomal carriers in nasal mucosae. The cationic emulsion was stable in the presence of heparin whereas the liposomal carriers became very unstable. Unlike DNA in liposome/DNA complexes, DNA in the emulsion/DNA complex was resistant to heparin exchange and DNase I digestion. The cationic emulsion was more effective in delivering DNA to nasal mucosae than commercially available liposomal carriers. The transfection activities of the lipid carriers in nasal cavity mucosae are in agreement with the stability of the lipid carriers and their complexes with DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10059-000-0142-1
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    Nuclear Magnetic Resonance and Infrared Spectroscopic Analysis of Nedocromil Hydrates (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 619-624 
    Details
    ISSN: 1573-904X
    Keywords: NMR ; infrared ; nedocromil ; hydrates ; solvate ; methanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Nedocromil sodium (NS), which is used in the treatment ofreversible obstructive airway diseases, such as asthma, has been foundto exist in the following solid phases: the heptahemihydrate, thetrihydrate, a monohydrate, an amorphous phase, which contains variableamounts of water, and a recently discovered methanol + water (MW)solvate. Our aim was to apply 13C solid-state nuclear magneticresonance (NMR) spectroscopy and solid-state Fourier transform infrared(FTIR) spectroscopy to the study of specific interactions in the varioussolid forms of NS. Methods. The 13 solid-state NMR and FTIR spectra of the varioussolid forms of NS were obtained and were related to the crystalstructures of NS, the conformations of the nedocromil anion, and theinteractions of the water molecules in these crystals. Results. The 13C solid-state NMR spectrum is sensitive to theconformation of the nedocromil anion, while the solid-state FTIR spectrumis sensitive to interactions of water molecules in the solid state. In NSmonohydrate, for which the crystal structure has not yet been solved,and in the amorphous phase, the information about the conformationsof the nedocromil anion and the interactions of the water moleculesare deduced from the 13C solid-state NMR spectra and solid-state FTIRspectra, respectively. Conclusions. 13C solid-state NMR spectroscopy and solid-state FTIRspectroscopy are shown to be powerful complementary tools forprobing the chemical environment of molecules in the solid state,specifically the conformation of the nedocromil anion and the interactions ofwater-molecules, respectively.
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    URL: http://dx.doi.org/10.1023/A:1007533419711
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    The Molecular Complexes of Calix[4]resorcinolarene with Diglycidylmethyl Phosphonate (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 153-162 
    Details
    ISSN: 1573-1111
    Keywords: calix[4]resorcinolarene ; diglycidylmethyl phosphonate ; complexation ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of strong molecular complexes of calix[4]recorcinolarene with the polyfunctional phosphoorganic compound diglycidylmethyl phosphonate was observed in organic media. Complexes of different compositions were obtained with the ratio of the initial reagents of 1 : 1 and 1 : 4. Three complexes were isolated and characterized by elemental analysis; their 1H and 13C NMR spectroscopic parameters are also discussed.
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    URL: http://dx.doi.org/10.1023/A:1008106732110
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    Synthesis and Conformational Studies of an Asymmetrical Dibenzo-16-crown-5 Carboxylic Acid (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 287-299 
    Details
    ISSN: 1573-1111
    Keywords: crown ether ; NMR ; complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Asymmetrical cis-5,6-dimethyl-6-oxyacetoxy-(2,3)(9,10)-dibenzo-16-crown-5 was synthesized by a multi-step sequence and its stereochemistry determined by NOE experiments. Introduction of the 6-methyl group markedly reduces the stability constant for complexation of Na+ and K+ by the ionized form of the lariat ether carboxylic acid.
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    URL: http://dx.doi.org/10.1023/A:1008078220916
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