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CHEMISTRY (587 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 5)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 32)
ACS Catalysis     Full-text available via subscription   (Followers: 28)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 15)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 10)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 25)
ACS Nano     Full-text available via subscription   (Followers: 203)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 11)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 6)
Acta Chromatographica     Full-text available via subscription   (Followers: 10)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 4)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 11)
Advanced Functional Materials     Hybrid Journal   (Followers: 40)
Advanced Science Focus     Free   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 23)
Advances in Chemical Science     Open Access   (Followers: 9)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Drug Research     Full-text available via subscription   (Followers: 18)
Advances in Enzyme Research     Open Access  
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 13)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 16)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Polymer Science     Hybrid Journal   (Followers: 39)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
African Journal of Chemical Education     Open Access   (Followers: 1)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 5)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Alchemy     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 5)
AMB Express     Open Access  
Ambix     Hybrid Journal   (Followers: 2)
American Journal of Applied Sciences     Open Access   (Followers: 30)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 85)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Chemistry     Open Access   (Followers: 19)
American Journal of Plant Physiology     Open Access   (Followers: 10)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 20)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 142)
Annales UMCS, Chemia     Open Access   (Followers: 2)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 1)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 2)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 11)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 11)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 13)
Applied Surface Science     Hybrid Journal   (Followers: 23)
Arabian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 4)
Autophagy     Full-text available via subscription   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 141)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal   (Followers: 1)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 4)
Bioinspired Materials     Open Access  
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 17)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 6)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 30)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 24)
Bioorganic Chemistry     Hybrid Journal   (Followers: 5)
Biopolymers     Hybrid Journal   (Followers: 14)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 3)
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 13)
C - Journal of Carbon Research     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 1)
Carbohydrate Research     Hybrid Journal   (Followers: 11)
Carbon     Hybrid Journal   (Followers: 55)
Catalysis for Sustainable Energy     Open Access   (Followers: 2)

        1 2 3 4 5 6 | Last

Journal Cover   Carbohydrate Research
  [SJR: 0.654]   [H-I: 83]   [11 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
   Published by Elsevier Homepage  [2811 journals]
  • Synthesis of a heparin-related GlcN–IdoA sulfation-site variable
           disaccharide library and analysis by Raman and ROA spectroscopy
    • Abstract: Publication date: 5 December 2014
      Source:Carbohydrate Research, Volume 400
      Author(s): Gavin J. Miller , Steen U. Hansen , Marek Baráth , Christian Johannessen , Ewan W. Blanch , Gordon C. Jayson , John M. Gardiner
      Synthesis of an array of differentially sulfated GlcN–IdoA disaccharides, accessible on good scale, directly from l-iduronate components is described. These are specifically directed to provide the sulfation variability at the key most common biologically relevant sulfation-variable l-IdoA O-2 and d-GlcN O-6 and amino sites of this heparin disaccharide. This sulfation-varied matrix has allowed the first evaluation of using Raman/ROA spectroscopy to characterize changes in spectra as a function of both site and level of sulfation with pure, defined heparin-related disaccharide species. This provides analysis of both similarities and differences to digest native heparin and this shows evidence of different types of changes in conformations and conformational freedom as a function of some specific sulfation changes at the disaccharide level. It is anticipated that this data set will open the way for applications to further site-specific sulfated saccharides and demonstrates the capability offered by Raman–ROA towards fingerprinting sulfation in heparin fragments.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Chain-growth polyglycosylation: synthesis of linker-equipped mannosyl
    • Abstract: Publication date: 11 February 2015
      Source:Carbohydrate Research, Volume 403
      Author(s): Heiko J. Schuster , Balakumar Vijayakrishnan , Benjamin G. Davis
      Direct syntheses of acetylated poly-mannosides can be achieved in one-step starting from a fully acetylated thioglycoside mannosyl donor using a polymerization-type strategy under the correct conditions. Under conditions that allow polymer growth from non-reducing to reducing end (N→R), different acceptor alcohols can be used as the ‘terminating acceptors’ to install different linkers at the reducing terminus. The efficiency is dependent on substituents of the linker, its length, temperature and choice of Lewis acid activator.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Enzymatic synthesis using glycoside phosphorylases
    • Abstract: Publication date: 11 February 2015
      Source:Carbohydrate Research, Volume 403
      Author(s): Ellis C. O’Neill , Robert A. Field
      Carbohydrate phosphorylases are readily accessible but under-explored catalysts for glycoside synthesis. Their use of accessible and relatively stable sugar phosphates as donor substrates underlies their potential. A wide range of these enzymes has been reported of late, displaying a range of preferences for sugar donors, acceptors and glycosidic linkages. This has allowed this class of enzymes to be used in the synthesis of diverse carbohydrate structures, including at the industrial scale. As more phosphorylase enzymes are discovered, access to further difficult to synthesise glycosides will be enabled. Herein we review reported phosphorylase enzymes and the glycoside products that they have been used to synthesise.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • A novel polyrotaxane-based delivery system for scutellarin: preparation,
           characterization, and in vitro evaluation
    • Abstract: Publication date: 18 October 2013
      Source:Carbohydrate Research, Volume 380
      Author(s): Rui-Jian Jiang , Bo Yang , Zhen-Kun Liu , Yu-Lin Zhao , Xia-Li Liao , Jian Yang , Chuan-Zhu Gao , Fen Wang , Bin Han
      The safe and effective polyrotaxane-based drug delivery system could potentially increase the antiproliferative activity of antitumor medicine. A novel scutellarin–polyrotaxane (SCU–PR), in which scutellarin (SCU) was covalently bound to one of the hydroxyl groups of polyrotaxane (PR), was synthesized, and its characterization was further investigated by NMR, XRD, TG, DSC. The cytotoxicity of SCU–PR was assessed in vitro using human HCT116 and LOVO cell lines in results that the IC50 values of SCU–PR (1.03×10−6 and 1.01×10−6 mol/L, respectively), which compared with those of free SCU (7.80×10−5 and 7.70×10−5 mol/L, respectively), were lower. The valuable properties of SCU–PR will be potentially useful for its application on human colon cancer chemotherapies.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Structural analysis of the O-acetylated O-polysaccharide isolated from
           Salmonella paratyphi A and used for vaccine preparation
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): N. Ravenscroft , P. Cescutti , M. Gavini , G. Stefanetti , C.A. MacLennan , L.B. Martin , F. Micoli
      Salmonella paratyphi A is increasingly recognized as a common cause of enteric fever cases and there are no licensed vaccines against this infection. Antibodies directed against the O-polysaccharide of the lipopolysaccharide of Salmonella are protective and conjugation of the O-polysaccharide to a carrier protein represents a promising strategy for vaccine development. O-Acetylation of S. paratyphi A O-polysaccharide is considered important for the immunogenicity of S. paratyphi A conjugate vaccines. Here, as part of a programme to produce a bivalent conjugate vaccine against both S. typhi and S. paratyphi A diseases, we have fully elucidated the O-polysaccharide structure of S. paratyphi A by use of HPLC–SEC, HPAEC–PAD/CD, GLC, GLC–MS, 1D and 2D-NMR spectroscopy. In particular, chemical and NMR studies identified the presence of O-acetyl groups on C-2 and C-3 of rhamnose in the lipopolysaccharide repeating unit, at variance with previous reports of O-acetylation at a single position. Moreover HR-MAS NMR analysis performed directly on bacterial pellets from several strains of S. paratyphi A also showed O-acetylation on C-2 and C-3 of rhamnose, thus this pattern is common and not an artefact from O-polysaccharide purification. Conjugation of the O-polysaccharide to the carrier protein had little impact on O-acetylation and therefore should not adversely affect the immunogenicity of the vaccine.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Shaping up for structural glycomics: a predictive protocol for
           oligosaccharide conformational analysis applied to N-linked glycans
    • Abstract: Publication date: 13 January 2014
      Source:Carbohydrate Research, Volume 383
      Author(s): Benedict M. Sattelle , Andrew Almond
      The human glycome comprises a vast untapped repository of 3D-structural information that holds the key to glycan recognition and a new era of rationally designed mimetic chemical probes, drugs, and biomaterials. Toward routine prediction of oligosaccharide conformational populations and exchange rates at thermodynamic equilibrium, we apply hardware-accelerated aqueous molecular dynamics to model μs motions in N-glycans that underpin inflammation and immunity. In 10μs simulations, conformational equilibria of mannosyl cores, sialyl Lewis (sLe) antennae, and constituent sub-sequences agreed with prior refinements (X-ray and NMR). Glycosidic linkage and pyranose ring flexing were affected by branching, linkage position, and secondary structure, implicating sequence dependent motions in glycomic functional diversity. Linkage and ring conformational transitions that have eluded precise quantification by experiment and conventional (ns) simulations were predicted to occur on μs timescales. All rings populated non-chair shapes and the stacked galactose and fucose pyranoses of sLea and sLex were rigidified, suggesting an exploitable 3D-signature of cell adhesion protein binding. Analyses of sLex dynamics over 25μs revealed that only 10μs were sufficient to explore all aqueous conformers. This simulation protocol, which yields conformational ensembles that are independent of initial 3D-structure, is proposed as a route to understanding oligosaccharide recognition and structure–activity relationships, toward development of carbohydrate-based novel chemical entities.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Fragment screening reveals salicylic hydroxamic acid as an inhibitor of
           Trypanosoma brucei GPI GlcNAc-PI de-N-acetylase
    • Abstract: Publication date: 31 March 2014
      Source:Carbohydrate Research, Volume 387
      Author(s): Michael D. Urbaniak , Amy S. Capes , Arthur Crossman , Sandra O’Neill , Stephen Thompson , Ian H. Gilbert , Michael A.J. Ferguson
      The zinc-metalloenzyme GlcNAc-PI de-N-acetylase is essential for the biosynthesis of mature GPI anchors and has been genetically validated in the bloodstream form of Trypanosoma brucei, which causes African sleeping sickness. We screened a focused library of zinc-binding fragments and identified salicylic hydroxamic acid as a GlcNAc-PI de-N-acetylase inhibitor with high ligand efficiency. This is the first small molecule inhibitor reported for the trypanosome GPI pathway. Investigating the structure activity relationship revealed that hydroxamic acid and 2-OH are essential for potency, and that substitution is tolerated at the 4- and 5-positions.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Synthesis of α-d-glucosyl substituted methyl glycosides of
           3-deoxy-α-d-manno- and d-glycero-α-d-talo-oct-2-ulosonic acid
           (Kdo/Ko) corresponding to inner core fragments of Acinetobacter
    • Abstract: Publication date: 4 June 2014
      Source:Carbohydrate Research, Volume 391
      Author(s): Barbara Pokorny , Sven Müller-Loennies , Paul Kosma
      The α-d-glucopyranosyl-(1→5)-substituted methyl glycosides of 3-deoxy-α-d-manno-oct-2-ulosonic acid (Kdo), 3-deoxy-α-d-lyxo-hept-2-ulosonic acid (Kdh), and d-glycero-α-d-talo-oct-2-ulosonic acid (Ko) were prepared using orthogonally protected glycosyl acceptor derivatives via glycosylation with a torsionally disarmed 4,6-O-benzylidene protected trifluoroacetimidate glucosyl donor followed by global deprotection. The related 6-O-phosphoryl-α-d-glucopyranosyl-(1→5)-substituted Kdo and Kdh derivatives were derived from a benzylidene-protected glucosyl intermediate using phosphoramidite and phosphoryl chloride-based phosphorylation steps, respectively. The deprotected disaccharides serve as ligands to study lectin binding of Acinetobacter lipopolysaccharide core oligosaccharides.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • NMR spectra of oligosaccharides at ultra-high field (900MHz) have better
           resolution than expected due to favourable molecular tumbling
    • Abstract: Publication date: 4 September 2006
      Source:Carbohydrate Research, Volume 341, Issue 12
      Author(s): Charles D. Blundell , Michelle A.C. Reed , Michael Overduin , Andrew Almond
      Nuclear magnetic resonance (NMR) remains the most promising technique for acquiring atomic-resolution information in complex carbohydrates. Significant obstacles to the acquisition of such data are the poor chemical-shift dispersion and artifacts resultant from their degenerate chemical structures. The recent development of ultra-high-field NMR (at 900MHz and beyond) gives new potential to overcome these problems, as we demonstrate on a hexasaccharide of the highly repetitive glycosaminoglycan hyaluronan. At 900MHz, the expected increase in spectral dispersion due to higher resonance frequencies and reduction in strong coupling-associated distortions are observed. In addition, the fortuitous molecular tumbling rate of oligosaccharides results in longer T 2-values that further significantly enhances resolution, an effect not available to proteins. Combined, the resolution enhancement can be as much as twofold relative to 600MHz, allowing all 1H-resonances in the hexasaccharide to be unambiguously assigned using standard natural-abundance experiments. The use of ultra-high-field spectrometers is clearly advantageous and promises a new and exciting era in carbohydrate structural biology.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Synthesis of potential metal-binding group compounds to examine the zinc
           dependency of the GPI de-N-acetylase metalloenzyme in Trypanosoma brucei
    • Abstract: Publication date: 1 May 2011
      Source:Carbohydrate Research, Volume 346, Issue 6
      Author(s): Nuha Z. Abdelwahab , Michael D. Urbaniak , Michael A.J. Ferguson , Arthur T. Crossman
      A small zinc-binding group (ZBG) library of deoxy-2-C-branched-monosaccharides, for example, 1,5-anhydroglucitols, consisting of either monodentate ligand binding carboxylic acids or bidentate ligand binding hydroxamic acids, were prepared to assess the zinc affinity of the putative metalloenzyme 2-acetamido-2-deoxy-α-d-glucopyranosyl-(1→6)-phosphatidylinositol de-N-acetylase (EC of glycosylphosphatidylinositol biosynthesis. The N-ureido thioglucoside was also synthesised and added to the ZBG library because a previous N-ureido analogue, synthesised by us, had inhibitory activity against the aforementioned de-N-acetylase, presumably via the N-ureido motif.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • A 3D-structural model of unsulfated chondroitin from high-field NMR:
           4-sulfation has little effect on backbone conformation
    • Abstract: Publication date: 26 January 2010
      Source:Carbohydrate Research, Volume 345, Issue 2
      Author(s): Benedict M. Sattelle , Javad Shakeri , Ian S. Roberts , Andrew Almond
      The glycosaminoglycan chondroitin sulfate is essential in human health and disease but exactly how sulfation dictates its 3D-strucutre at the atomic level is unclear. To address this, we have purified homogenous oligosaccharides of unsulfated chondroitin (with and without 15N-enrichment) and analysed them by high-field NMR to make a comparison published chondroitin sulfate and hyaluronan 3D-structures. The result is the first full assignment of the tetrasaccharide and an experimental 3D-model of the hexasaccharide (PDB code 2KQO). In common with hyaluronan, we confirm that the amide proton is not involved in strong, persistent inter-residue hydrogen bonds. However, in contrast to hyaluronan, a hydrogen bond is not inferred between the hexosamine OH-4 and the glucuronic acid O5 atoms across the β(1→3) glycosidic linkage. The unsulfated chondroitin bond geometry differs slightly from hyaluronan by rotation about the β(1→3) ψ dihedral (as previously predicted by simulation), while the β(1→4) linkage is unaffected. Furthermore, comparison shows that this glycosidic linkage geometry is similar in chondroitin-4-sulfate. We therefore hypothesise that both hexosamine OH-4 and OH-6 atoms are solvent exposed in chondroitin, explaining why it is amenable to sulfation and hyaluronan is not, and also that 4-sulfation has little effect on backbone conformation. Our conclusions exemplify the value of the 3D-model presented here and progress our understanding of glycosaminoglycan molecular properties.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • 1-Deoxy-d-galactonojirimycins with dansyl capped N-substituents as
           β-galactosidase inhibitors and potential probes for GM1
           gangliosidosis affected cell lines
    • Abstract: Publication date: 6 September 2011
      Source:Carbohydrate Research, Volume 346, Issue 12
      Author(s): Richard F.G. Fröhlich , Richard H. Furneaux , Don J. Mahuran , Robert Saf , Arnold E. Stütz , Michael B. Tropak , Jacqueline Wicki , Stephen G. Withers , Tanja M. Wrodnigg
      Two simple and reliably accessible intermediates, N-carboxypentyl- and N-aminohexyl-1-deoxy-d-galactonojirimycin were employed for the synthesis of a set of terminally N-dansyl substituted derivatives. Reaction of the terminal carboxylic acid of N-carboxypentyl-1-deoxy-d-galactonojirimycin with N-dansyl-1,6-diaminohexane provided the chain-extended fluorescent derivative. Employing bis(6-dansylaminohexyl)amine, the corresponding branched di-N-dansyl compound was obtained. Partially protected N-aminohexyl-1-deoxy-d-galactonojirimycin served as intermediate for two additional chain-extended fluorescent 1-deoxy-d-galactonojirimycin (1-DGJ) derivatives featuring terminal dansyl groups in the N-alkyl substituent. These new compounds are strong inhibitors of d-galactosidases and may serve as leads en route to pharmacological chaperones for GM1-gangliosidosis.
      Graphical abstract image Highlights ► N-Alkylation of 1-deoxy-D-galactonojirimycin with dansylamino terminated spacer arms provides powerful inhibitors. ► These enhance mutant lysosomal -galactosidase activities in GM1 gangliosidosis cell lines. ► Based on their fluorescence, they can serve as selective intracellular organellar probes.

      PubDate: 2015-04-27T18:44:21Z
  • Towards multivalent CD1d ligands: synthesis and biological activity of
           homodimeric α-galactosyl ceramide analogues
    • Abstract: Publication date: 15 July 2012
      Source:Carbohydrate Research, Volume 356
      Author(s): Peter J. Jervis , Marie Moulis , John-Paul Jukes , Hemza Ghadbane , Liam R. Cox , Vincenzo Cerundolo , Gurdyal S. Besra
      A library of dimeric CD1d ligands, containing two α-galactosyl ceramide (α-GalCer) units linked by spacers of varying lengths has been synthesised. The key dimerisation reactions were carried out via copper-catalysed click reactions between a 6″-azido-6″-deoxy-α-galactosyl ceramide derivative and various diynes. Each α-GalCer dimer was tested for its ability to stimulate iNKT cells.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Catalytic mechanism of human UDP-glucose 6-dehydrogenase: in situ proton
           NMR studies reveal that the C-5 hydrogen of UDP-glucose is not exchanged
           with bulk water during the enzymatic reaction
    • Abstract: Publication date: 15 July 2012
      Source:Carbohydrate Research, Volume 356
      Author(s): Thomas Eixelsberger , Lothar Brecker , Bernd Nidetzky
      Human UDP-glucose 6-dehydrogenase (hUGDH) catalyzes the biosynthetic oxidation of UDP-glucose into UDP-glucuronic acid. The catalytic reaction proceeds in two NAD+-dependent steps via covalent thiohemiacetal and thioester enzyme intermediates. Formation of the thiohemiacetal adduct occurs through attack of Cys276 on C-6 of the UDP-gluco-hexodialdose produced in the first oxidation step. Because previous studies of the related enzyme from bovine liver had suggested loss of the C-5 hydrogen from UDP-gluco-hexodialdose due to keto-enol tautomerism, we examined incorporation of solvent deuterium into product(s) of UDP-glucose oxidation by hUGDH. We used wild-type enzyme and a slow-reacting Glu161→Gln mutant that accumulates the thioester adduct at steady state. In situ proton NMR measurements showed that UDP-glucuronic acid was the sole detectable product of both enzymatic transformations. The product contained no deuterium at C-5 within the detection limit (⩽2%). The results are consistent with the proposed mechanistic idea for hUGDH that incipient UDP-gluco-hexodialdose is immediately trapped by thiohemiacetal adduct formation.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Crystal and molecular structure of methyl
           l-glycero-α-d-manno-heptopyranoside, and synthesis of 1→7
           linked l-glycero-d-manno-heptobiose and its methyl α-glycoside
    • Abstract: Publication date: 27 September 2011
      Source:Carbohydrate Research, Volume 346, Issue 13
      Author(s): Daniel Artner , Christian Stanetty , Kurt Mereiter , Alla Zamyatina , Paul Kosma
      Methyl l-glycero-α-d-manno-heptopyranoside was synthesized in good yield by a Fischer-type glycosylation of the heptopyranose with methanol in the presence of cation-exchange resin under reflux and microwave conditions, respectively. The compound crystallized from 2-propanol in an orthorhombic lattice of space group P21212 showing a comparatively porous structure with a 2-dimensional O–H⋯O hydrogen bond network. As model compounds for the side chain domains of the inner core structure of bacterial lipopolysaccharide, l-glycero-α-d-manno-heptopyranosyl-(1→7)-l-glycero-d-manno-heptopyranose and the corresponding disaccharide methyl α-glycoside were prepared. The former compound was generated via glycosylation of a benzyl 5,6-dideoxy-hept-5-enofuranoside intermediate followed by catalytic osmylation and deprotection. The latter disaccharide was efficiently synthesized in good yield by a straightforward coupling of an acetylated N-phenyltrifluoroacetimidate heptopyranosyl donor to a methyl 2,3,4,6-tetra-O-acetyl heptopyranoside acceptor derivative followed by Zemplén deacetylation.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • 2,2,2-Trifluoroethyl 6-thio-β-d-glucopyranoside as a selective tag
           for cysteines in proteins
    • Abstract: Publication date: 1 November 2012
      Source:Carbohydrate Research, Volume 361
      Author(s): Richard F.G. Fröhlich , Evelyne Schrank , Klaus Zangger
      A synthetic route to a trifluoromethyl and thiol containing glucose derivative (2,2,2-trifluoroethyl 6-thio-β-d-glucopyranoside) is presented, which is based on microwave-assisted Fischer glycosylation under increased pressure. This water-soluble, neutral thiol-compound can be used to selectively introduce a fluorine probe for 19F NMR spectroscopy on cysteines in proteins. It can be attached under mild conditions in an aqueous environment without the risk of denaturing the protein. This tag has been applied to determine the redox-state of two cysteine residues in a bacterial transcription activator. Qualitative information about the solvent accessibility can be obtained from F-19 solvent PREs.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety
    • Abstract: Publication date: 1 October 2012
      Source:Carbohydrate Research, Volume 360
      Author(s): Andrew G. Cook , James L. Wardell , Nicholas J. Brooks , John M. Seddon , Alfonso Martínez-Felipe , Corrie T. Imrie
      The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(d-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4′-oxy)]octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase.
      Graphical abstract image Highlights ► A novel non-symmetric liquid crystal dimer is reported containing a sugar moiety. ► The dimer shows glassy behaviour and a highly interdigitated smectic A phase. ► The hydrogen bonding does not show a marked change at either T g or T SmAI. ► The smectic A-isotropic transition is driven by changes in van der Waals interactions. ► Hydrogen bonded aggregates persist into the isotropic phase.

      PubDate: 2015-04-27T18:44:21Z
  • In vivo incorporation of an azide-labeled sugar analog to detect mammalian
           glycosylphosphatidylinositol molecules isolated from the cell surface
    • Abstract: Publication date: 15 November 2012
      Source:Carbohydrate Research, Volume 362
      Author(s): Saulius Vainauskas , Leslie K. Cortes , Christopher H. Taron
      N-Acetylgalactosamine (GalNAc) linked to the first mannose of glycosylphosphatidylinositol (GPI) core has been previously reported to be heterogeneously present on some mammalian GPI-anchored proteins. Here we present a method for profiling GalNAc-containing GPI-anchored proteins in mammalian cells by metabolic labeling with tetraacetylated N-azidoacetylgalactosamine (GalNAz) followed by biotinylation of the incorporated sugar analog. We have labeled both endogenous and recombinant GPI-anchored proteins with GalNAz, and demonstrated that the azide-activated sugar gets incorporated into the GPI glycan, likely as an unsubstituted side branch of the core structure. GalNAz was detected only on GPI molecules attached to proteins, and not on GPI precursors, indicating that GalNAc modification takes place after the GPI anchor is transferred to protein. We have highlighted the utility of this cell labeling approach by demonstrating the ability to examine specific GalNAc-containing GPI-anchored proteins isolated non-destructively from separate membrane domains (apical and basolateral) in polarized epithelial cells. This study represents the first demonstration of site-specific in vivo labeling of a GPI moiety with a synthetic sugar analog.
      Graphical abstract image Highlights ► GPIs can be labeled in vivo with N-azidoacetylgalactosamine (GalNAz). ► GalNAz incorporates only into GPI molecules attached to proteins. ► Method allows examination of the heterogeneous GalNAc modification on GPI proteins. ► Approach permits analysis of GPI proteins from discrete domains of polarized cells.

      PubDate: 2015-04-27T18:44:21Z
  • Stability of aminooxy glycosides to glycosidase catalysed hydrolysis
    • Abstract: Publication date: 9 August 2013
      Source:Carbohydrate Research, Volume 377
      Author(s): Amjid Iqbal , Hicham Chibli , Chris J. Hamilton
      The stability of the amino(methoxy) beta-glycosidic bond to glycosidase catalysed hydrolysis is reported. Beta-O-benzyl glucose and beta-O-benzyl galactose are substrates hydrolysed by beta-glucosidase and beta-galactosidase from almonds and Escherichia coli, respectively. However their beta-N-benzyl-(O-methoxy)-glucoside and beta-N-benzyl-(O-methoxy)-galactoside derivatives are competitive inhibitors.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • A linear synthesis of gemcitabine
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Kylie Brown , Alex Weymouth-Wilson , Bruno Linclau
      Gemcitabine, 2′-deoxy-2′,2′-difluorocytidine, is currently prescribed against a number of cancers. Here we report a linear synthesis of gemcitabine with a high-yielding direct conversion of 3,5-di-O-benzoyl-2-deoxy-2,2-difluororibose into the corresponding glycosyl urea as the key step, followed by conventional conversion to the cytosine base via the uracil derivative. The process proceeded with modest anomeric selectivity.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
  • Enzymatic synthesis of nucleobase-modified UDP-sugars: scope and
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Ben A. Wagstaff , Martin Rejzek , Thomas Pesnot , Lauren M. Tedaldi , Lorenzo Caputi , Ellis C. O’Neill , Stefano Benini , Gerd K. Wagner , Robert A. Field
      Glucose-1-phosphate uridylyltransferase in conjunction with UDP-glucose pyrophosphorylase was found to catalyse the conversion of a range of 5-substituted UTP derivatives into the corresponding UDP-galactose derivatives in poor yield. Notably the 5-iodo derivative was not converted to UDP-sugar. In contrast, UDP-glucose pyrophosphorylase in conjunction with inorganic pyrophosphatase was particularly effective at converting 5-substituted UTP derivatives, including the iodo compound, into a range of gluco-configured 5-substituted UDP-sugar derivatives in good yields. Attempts to effect 4″-epimerization of these 5-substituted UDP-glucose with UDP-glucose 4″-epimerase from yeast were unsuccessful, while use of the corresponding enzyme from Erwinia amylovora resulted in efficient epimerization of only 5-iodo-UDP-Glc, but not the corresponding 5-aryl derivatives, to give 5-iodo-UDP-Gal. Given the established potential for Pd-mediated cross-coupling of 5-iodo-UDP-sugars, this provides convenient access to the galacto-configured 5-substituted-UDP-sugars from gluco-configured substrates and 5-iodo-UTP.
      Graphical abstract image

      PubDate: 2015-04-27T18:44:21Z
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