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  Subjects -> CHEMISTRY (Total: 814 journals)
    - ANALYTICAL CHEMISTRY (49 journals)
    - CHEMISTRY (566 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
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CHEMISTRY (566 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 4)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Catalysis     Full-text available via subscription   (Followers: 25)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 8)
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: 355)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 9)
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: 10)
Advanced Functional Materials     Hybrid Journal   (Followers: 38)
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: 4)
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: 4)
AMB Express     Open Access  
American Journal of Applied Sciences     Open Access   (Followers: 31)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 213)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Chemistry     Open Access   (Followers: 18)
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: 36)
Angewandte Chemie     Hybrid Journal   (Followers: 18)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 273)
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: 4)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 11)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 12)
Applied Surface Science     Hybrid Journal   (Followers: 20)
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: 1)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 261)
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: 5)
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: 1)
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 13)
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)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 6)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 7)

        1 2 3 4 5 6 | Last

Journal Cover   Carbohydrate Research
  [SJR: 0.675]   [H-I: 77]   [13 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
   Published by Elsevier Homepage  [2589 journals]
  • Hydrolysis of wheat flour arabinoxylan, acid-debranched wheat flour
           arabinoxylan and arabino-xylo-oligosaccharides by β-xylanase,
           α-l-arabinofuranosidase and β-xylosidase
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Barry V. McCleary , Vincent A. McKie , Anna Draga , Edward Rooney , David Mangan , Jennifer Larkin
      A range of α-l-arabinofuranosyl-(1-4)-β-d-xylo-oligosaccharides (AXOS) were produced by hydrolysis of wheat flour arabinoxylan (WAX) and acid debranched arabinoxylan (ADWAX), in the presence and absence of an AXH-d3 α-l-arabinofuranosidase, by several GH10 and GH11 β-xylanases. The structures of the oligosaccharides were characterised by GC-MS and NMR and by hydrolysis by a range of α-l-arabinofuranosidases and β-xylosidase. The AXOS were purified and used to characterise the action patterns of the specific α-l-arabinofuranosidases. These enzymes, in combination with either Cellvibrio mixtus or Neocallimastix patriciarum β-xylanase, were used to produce elevated levels of specific AXOS on hydrolysis of WAX, such as 32-α-l-Araf-(1-4)-β-d-xylobiose (A3X), 23-α-l-Araf-(1-4)-β-d-xylotriose (A2XX), 33-α-l-Araf-(1-4)-β-d-xylotriose (A3XX), 22-α-l-Araf-(1-4)-β-d-xylotriose (XA2X), 32-α-l-Araf (1-4)-β-d-xylotriose (XA3X), 23-α-l-Araf-(1-4)-β-d-xylotetraose (XA2XX), 33-α-l-Araf-(1-4)-β-d-xylotetraose (XA3XX), 23,33-di-α-l-Araf-(1-4)-β-d-xylotriose (A2+3XX), 23,33-di-α-l-Araf-(1-4)-β-d-xylotetraose (XA2+3XX), 24,34-di-α-l-Araf-(1-4)-β-d-xylopentaose (XA2+3XXX) and 33,34-di-α-l-Araf-(1-4)-β-d-xylopentaose (XA3A3XX), many of which have not previously been produced in sufficient quantities to allow their use as substrates in further enzymic studies. For A2,3XX, yields of approximately 16% of the starting material (wheat arabinoxylan) have been achieved. Mixtures of the α-l-arabinofuranosidases, with specific action on AXOS, have been combined with β-xylosidase and β-xylanase to obtain an optimal mixture for hydrolysis of arabinoxylan to l-arabinose and d-xylose.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Isolation and characterization of unhydrolyzed oligosaccharides from
           switchgrass (Panicum virgatum, L.) xylan after exhaustive enzymatic
           treatment with commercial enzyme preparations
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Michael J. Bowman , Bruce S. Dien , Karl E. Vermillion , Jeffrey A. Mertens
      Switchgrass (Panicum virgatum, L.) is a potential renewable source of carbohydrates for use in microbial conversion to biofuels. Xylan comprises approximately 30% of the switchgrass cell wall. To understand the limitations of commercial enzyme mixtures, alkali-extracted, isolated switchgrass xylan was hydrolyzed by the action of two commercial enzyme cocktails, in the presence and absence of an additional α-arabinofuranosidase enzyme. The two most abundant enzymatic digestion products from each commercial enzyme treatment were separated and characterized by LC-MS n , linkage analysis, and NMR. The most abundant oligosaccharide from each commercial cocktail was susceptible to hydrolysis when supplemented with a GH62 α-arabinofuranosidase enzyme; further characterization confirmed the presence of (1→3)-α-arabinose linkages. These results demonstrate the lack of the required selectivity for arabinose-containing substrates in the commercial enzyme preparations tested. One product from each condition remained intact and was found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains; this linkage acts as a source of oligosaccharide recalcitrance.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Characteristics of mannosylerythritol lipids and their environmental
           potential
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Mingda Yu , Zhifeng Liu , Guangming Zeng , Hua Zhong , Yang Liu , Yongbing Jiang , Min Li , Xiaoxiao He , Yan He
      Mannosylerythritol lipids (MELs) are promising biosurfactants containing two glycosyl derivatives and various fatty acids, which are mainly secreted by Pseudozyma as well as Ustilago. In this review, the latest research is demonstrated on production conditions, structural diversity, self-assembling properties and versatile biochemical functions of MELs. The genetic study and synthetic pathways, which mainly influence the type and yield of MELs production. Due to the excellent surface activity, biocompatibility and restorative function, MELs can be used in enviornmental industry, which has not been widely noted. In this paper, the current status of research on enviornmental potential of MELs has been discussed including petroleum degradation, bioconversion of chemical wastes and enhanced bioremediation of amphiphilic wastes.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Isolation and characterization of feruloylated arabinoxylan
           oligosaccharides from the perennial cereal grain intermediate wheat grass
           (Thinopyrum intermedium)
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Rachel R. Schendel , Andreas Becker , Catrin E. Tyl , Mirko Bunzel
      In comparison to the annual grain crops dominating current agricultural production, perennial grain species require fewer chemical and energy inputs and improve soil health and erosion control. The possibility for producing sustainable grain harvests from marginal land areas is motivating research initiatives to integrate perennial grains into commercial cropping and food processing systems. In this study, the feruloylated arabinoxylans from intermediate wheat grass (Thinopyrum intermedium, IWG), a promising perennial grain candidate in agronomic screening studies, were investigated. Insoluble fiber isolated from IWG whole grain flour was subjected to either mildly acidic (50 mM TFA, 100 °C, 2 h) or enzymatic (Driselase) hydrolysis. The liberated feruloylated arabinoxylan oligosaccharides were concentrated with Amberlite XAD-2, separated with gel chromatography (Sephadex LH-20, water), and purified with reversed-phase HPLC (C18, water-MeOH gradient). Thirteen feruloylated oligosaccharides were isolated (including eight structures described for the first time) and identified by LC-ESI-MS and NMR. Linkage-type analysis via methylation analysis, as well as the monosaccharide and phenolic acid profiles of the IWG insoluble fiber were also determined. IWG feruloylated arabinoxylans have a relatively simple structure with only short feruloylated side chains, a lower backbone substitution rate than annual rye and wheat varieties, and a moderate phenolic acid content.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Spectroscopic and structural studies on lactose species in aqueous
           solution combining the HATR and Raman spectra with SCRF calculations
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): María Jimena Márquez , Alicia Beatriz Brizuela , Lilian Davies , Silvia Antonia Brandán
      In this work, the α and β isomers, the α-lactose monohydrate and dihydrate and the dimeric species of lactose were studied from the spectroscopic point of view in gas and aqueous solution phases combining the infrared, Horizontal Attenuated Total Reflectance (HATR) and Raman spectra with the density functional theory (DFT) calculations. Aqueous saturated solutions of α-lactose monohydrate and solutions at different molar concentrations of α-lactose monohydrate in water were completely characterized by infrared, HATR and Raman spectroscopies. For all the species in solution, the solvent effects were studied using the solvation polarizable continuum (PCM) and solvation (SM) models and, then, their corresponding solvation energies were predicted. The vibrational spectra of those species in aqueous solution were completely assigned by employing the Scaled Quantum Mechanics Force Field (SQMFF) methodology and the self-consistent reaction field (SCRF) calculations. The stabilities of all those species were studied by using the natural bond orbital (NBO), and atoms in molecules (AIM) calculations.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Fragment profiling of low molecular weight heparins using reversed phase
           ion pair liquid chromatography-electrospray mass spectrometry
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Xiaohui Xu , Daoyuan Li , Lequan Chi , Xuzhao Du , Xue Bai , Lianli Chi
      Low molecular weight heparins (LMWHs) are linear and highly charged carbohydrate polymers prepared by chemical or enzymatic depolymerization of heparin. Compared to unfractionated heparin (UFH), LMWHs are prevalently used as clinical anticoagulant drugs due to their lower side effects and better bioavailability. The work presented herein provides a rapid and powerful fragment mapping method for structural characterization of LMWHs. The chain fragments of two types of LMWHs, enoxaparin and nadroparin, were generated by controlled enzymatic digestion with each of heparinase I (Hep I, Enzyme Commission (EC) # 4.2.2.7), heparinase II (Hep II, no EC # assigned) and heparinase III (Hep III, EC # 4.2.2.8). Reversed phase ion pair high performance liquid chromatography (RPIP-HPLC) coupled with electrospray ion trap time-of-flight mass spectrometry (ESI-IT-TOF-MS) was used to profile the oligosaccharide chains ranging from disaccharides to decasaccharides. A database containing all theoretical structural compositions was established to assist the mass spectra interpretation. The six digests derived by three enzymes from two types of LMWHs exhibited distinguishable fingerprinting patterns. And a total of 94 enoxaparin fragments and 109 nadroparin fragments were detected and identified. Besides the common LMWH oligosaccharides, many components containing characteristic LMWH structures such as saturated l-idopyranosuronic acid, 2,5-anhydro-d-mannitol, 1,6-anhydro-d-aminopyranose, as well as odd number oligosaccharides were also revealed. Quantitative comparison of major components derived from innovator and generic nadroparin products was presented. This approach to profile LMWHs' fragments offers a highly reproducible, high resolution and information-rich tool for evaluating the quality of this category of anticoagulant drugs or comparing structural similarities among samples from various sources.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Kinetic characterization of Aspergillus niger chitinase CfcI using a
           HPAEC-PAD method for native chitin oligosaccharides
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Jolanda M. van Munster , Peter Sanders , Geralt A. ten Kate , Lubbert Dijkhuizen , Marc J.E.C. van der Maarel
      The abundant polymer chitin can be degraded by chitinases (EC 3.2.1.14) and β-N-acetyl-hexosaminidases (EC 3.2.1.52) to oligosaccharides and N-acetyl-glucosamine (GlcNAc) monomers. Kinetic characterization of these enzymes requires product quantification by an assay method with a low detection limit, preferably compatible with the use of native, non-labeled substrates. Here we report a quantitative HPAEC-PAD method that allows fast separation of chitin oligosaccharides (COS) ranging from (GlcNac)1–6 at detection limits of 1–3 pmol and a linear range of 5–250 pmol. Quantification under intra- and interday precision conditions was performed with 2.1–5.4% relative standard deviation (RSD) and 1.2–10.3% RSD, respectively. This method was successfully used for the determination of the kinetic parameters of the Aspergillus niger chitinase CfcI with native COS. CfcI was recently shown to release GlcNAc from the reducing end of COS, a new activity for fungal chitinases. A Carbohydrate Binding Module of family 18 (CBM18) is inserted in the CfcI catalytic domain. Site directed mutagenesis was used to assess the functionality of this CfcI-CBM18: four of its key amino acids were replaced by glycine residues, yielding CfcISYNF. Comparison of the kinetic parameters of CfcI and CfcISYNF confirmed that this CBM18 is functionally involved in catalysis.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structure of a zwitterionic O-polysaccharide from Photorhabdus temperata
           subsp. cinerea 3240
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Anna N. Kondakova , Nadezhda A. Kirsheva , Nikolay P. Arbatsky , Rima Z. Shaikhutdinova , Alexander S. Shashkov , Sergey A. Ivanov , Andrey P. Anisimov , Yuriy A. Knirel
      A phosphorylated O-polysaccharide was isolated from the lipopolysaccharide of an entomopathogenic bacterium Photorhabdus temperata subsp. cinerea 3240 and studied by sugar analysis, dephosphorylation, and 1H and 13C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit of the O-polysaccharide was established: →3)-β-d-GalpNAc4PEtN-(1→4)-β-d-GlcpA-(1→3)-β-d-FucpNAc4N-(1→ where GlcA indicates glucuronic acid, FucNAc4N 2-acetamido-4-amino-2,4,6-trideoxygalactose, and PEtN 2-aminoethyl phosphate.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Mass spectrometry-based method to investigate the natural selectivity of
           sucrose as the sugar transport form for plants
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Hang Yuan , Yile Wu , Wu Liu , Yan Liu , Xiang Gao , Jinming Lin , Yufen Zhao
      Sucrose is the carbon skeletons and energy vector for plants, which is important for plants growth. Among thousands of disaccharides in Nature, why chose sucrose for plants? In this paper, we analyzed the intrinsic structural characteristics of four sucrose isomers with different glycosidic linkage by mass spectrometry (MS) technique. Our results show that sucrose has the most labile glycosidic bond compared with other three isomers, which is helpful for releasing glucose and fructose unit. Besides, sucrose has the most stable integral structure, which is hard to dehydrate and degrade into fragments through losing one or three even four-carbon units, just as its three isomers. In other words, sucrose is more easily holds an integral structure during the transport process, whenever it is necessary, and sucrose can be cleaved into glucose and fructose easily. Besides, we also investigate the internal relationship of sucrose with K+ by tandem mass spectrometry and viscosity measurement. The related results have shown that the K+ can stabilize sucrose to a greater extent than the Na+. Furthermore, under the same conditions, K+ ions reduce the viscosity of sucrose–water system much more than Na+. These results suggest that K+ is a better co-transporter for sucrose. Of course, the transport of sucrose in plants is a very complicated process, which is involved in many proteins. This paper directly accounts for the basic structure feature of sucrose, and the results discovered could provide the novel insight for the answer why Nature chose sucrose for plants.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Nuclear magnetic resonance studies of the interactions between the organic
           germanium compound Ge-132 and saccharides
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Yasuhiro Shimada , Katsuyuki Sato , Yoshihiko Tokuji , Takashi Nakamura
      Poly-trans-[(2-carboxyethyl)germasesquioxane], Ge-132, is a water-soluble organic germanium compound with many reported physiological functions. The hydrolysate of Ge-132, 3-(trihydroxygermyl)propanoic acid, can interact with diol compounds; therefore, it can possibly interact with diol-containing sugar compounds, which have important physiological functions in sugar chains, glycoproteins, and glucolipids. In this study, we examined the interaction between sodium 3-(trihydroxygermyl)propanoate and monosaccharides using nuclear magnetic resonance. When 1,4-anhydroerythritol was mixed with sodium 3-(trihydroxygermyl)propanoate, a pattern of signals different from that obtained for each solute alone was observed. Some signals were broader, and novel signals with different chemical shifts appeared to originate from complex formation. Spectral observations for sodium 3-(trihydroxygermyl)propanoate and the sugar isomers of glucose and fructose indicated that sodium 3-(trihydroxygermyl)propanoate has a higher affinity for fructose (a ketose) than glucose (an aldose). Moreover, the β-furanosyl conformation of fructose was the structure that interacted most with sodium 3-(trihydroxygermyl)propanoate. These results demonstrate the ability of aqueous Ge-132 to form complexes with the cis-diol structures of saccharides. Thus, interactions among 3-(trihydroxygermyl)propanoic acid and the important biological sugar compounds might be implicated in the physiological function of Ge-132.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Room-temperature ionic liquids enhanced green synthesis of β-glycosyl
           1-ester
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Yanli Cui , Minghan Xu , Weirong Yao , Jianwei Mao
      We herein report an efficient synthesis of β-glycosyl 1-ester in room-temperature ionic liquids (RTILs) promoted via silver salt and quaternary ammonium salt (PTC) with good or excellent yields. All products were isolated exclusively as the β-anomers. Four different RTILs, eight metal salts and four quaternary ammonium salts were screened in the glycosylation reaction. The synergistic effect of C6mim·OTf, Ag2O and tetrabutylammonium iodine gave the best results. Their promotion to the system was integral. Thorough study provided insight into the catalytic activity of ionic liquid structure, metal salts and quaternary ammonium salt to these reactions. It is worth mentioning that the yield of aliphatic compound 2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl butyrate (3l) was highly improved when using C6mim·OTf as solvent compared with the normal volatile solvents under the same catalysts. This green approach has been proved to be practical and compatible with a wide range from aliphatic to aromatic substrates.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structural studies of O-polysaccharide isolated from Cronobacter sakazakii
           Sequence Type 12 from a case of neonatal necrotizing enterocolitis
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Kinga Marszewska , Małgorzata Czerwicka , Stephen J. Forsythe , Karolina Ossowska , Halina Dziadziuszko , Zbigniew Kaczyński
      The O-polysaccharide (OPS) of Cronobacter sakazakii NTU 696 (Sequence Type 12) from a case of neonatal necrotizing enterocolitis was isolated from the polysaccharide fraction obtained after lipopolysaccharide (LPS) hydrolysis. Purified OPS was analyzed by NMR spectroscopy (1H, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC experiments) and chemical methods. Obtained monosaccharide derivatives analyzed by gas chromatography and gas chromatography-mass spectrometry allowed the identification of six sugar components. Performed experiments enabled to establish a structure of the OPS repeating unit of C. sakazakii NTU 696, as:
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structure and genetics of the O-antigen of Enterobacter cloacae G3054
           containing di-N-acetylpseudaminic acid
    • Abstract: Publication date: 30 April 2015
      Source:Carbohydrate Research, Volume 407
      Author(s): Andrei V. Perepelov , Min Wang , Andrei V. Filatov , Xi Guo , Alexander S. Shashkov , Lei Wang , Yuriy A. Knirel
      Mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3054 resulted in the cleavage of the O-polysaccharide at the linkage of residues of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac) in the main chain. The resultant oligosaccharide and an alkali-treated lipopolysaccharide were studied by sugar analysis along with 1H and 13C NMR spectroscopy, and the following structure of the branched pentasaccharide O-unit of the O-polysaccharide was established: The O-antigen gene cluster of E. cloacae G3054 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Editorial board
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406




      PubDate: 2015-03-01T16:48:40Z
       
  • Graphical contents list
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406




      PubDate: 2015-03-01T16:48:40Z
       
  • Synthesis, emulsification and self-assembly properties of sugar-containing
           semifluorinated amphiphiles
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Andrew V. Razgulin , Sandro Mecozzi
      Surfactants with two and three monosaccharide-based heads and a perfluoroalkyl tail have been synthesized. Perfluoroalkyl C3-symmetric triol and C2-symmetric diol were conveniently prepared via Cu-catalyzed azide–alkyne cycloaddition between a fluorous alkyne and tertiary and secondary azides, respectively. Glycosylation of the perfluoroalkyl diol and triol led to orthoester-type structures, which were evaluated for their capacity to stabilize aqueous emulsions of highly fluorinated anesthetics. The self-assembly properties of the tri-sugar amphiphile were examined by transmission electron microscopy.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • ‘Click chemistry’ synthesis of
           1-(α-d-mannopyranosyl)-1,2,3-triazoles for inhibition of
           α-mannosidases
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Monika Poláková , Rhiannon Stanton , Iain B.H. Wilson , Ivana Holková , Sergej Šesták , Eva Machová , Zuzana Jandová , Juraj Kóňa
      Three new triazole conjugates derived from d-mannose were synthesized and assayed in in vitro assays to investigate their ability to inhibit α-mannosidase enzymes from the glycoside hydrolase (GH) families 38 and 47. The triazole conjugates were more selective for a GH47 α-mannosidase (Aspergillus saitoi α1,2-mannosidase), showing inhibition at the micromolar level (IC50 values of 50–250 μM), and less potent towards GH38 mannosidases (IC50 values in the range of 0.5–6 mM towards jack bean α-mannosidase or Drosophila melanogaster lysosomal and Golgi α-mannosidases). The highest selectivity ratio [IC50(GH38)/IC50(GH47)] of 100 was exhibited by the phenyltriazole conjugate. To understand structure-activity properties of synthesized compounds, 3-D complexes of inhibitors with α-mannosidases were built using molecular docking calculations.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • The application of 2,2,2-trichloroethyl sulfate to the synthesis of
           chondroitin sulfate C and D
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Kenya Matsushita , Tomomi Nakata , Jun-ichi Tamura
      Chondroitin sulfates (CSs) have characteristic bioactivities that depend on sulfation patterns. Chemically synthesized CS oligosaccharides are valuable tools for elucidating the relationship between structures and bioactivities. 2,2,2-Trichloroethyl (TCE) sulfated sugars are highly soluble in nonpolar solvents, which is useful for the synthesis of sulfated oligosaccharides. We herein synthesized CS-C [βGalNAc6S(1–4)βGlcA] (1) and CS-D [βGalNAc6S(1–4)βGlcA2S] (2) disaccharides that possessed sulfate groups by TCE sulfation at O-6 of GalNAc and an additional sulfate group at O-2 of GlcA, respectively. We revealed the superior functionalities of TCE sulfates during the synthesis of CS-C and -D, despite the unwanted side reactions in the acetamido-containing substrate.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Ruthenium catalyzed synthesis of 2,3-unsaturated C-glycosides from glycals
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Batthula Srinivas , Thurpu Raghavender Reddy , Sudhir Kashyap
      A highly efficient and convenient C-glycosylation method was developed using ruthenium(III) chloride for the synthesis of 2,3-unsaturated C-glycosides. Various nucleophiles such as allyl trimethylsilane, triethylsilane, trimethylsilyl cyanide, trimethylsilyl azide and heterocycles such as thiophene and furan reacted smoothly with glycals in the presence of catalytic amount of ruthenium trichloride under mild reaction conditions.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Preparation, spectroscopy and molecular modelling studies of the inclusion
           complex of cordycepin with cyclodextrins
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Jian-Qiang Zhang , Di Wu , Kun-Ming Jiang , Da Zhang , Xi Zheng , Chun-Ping Wan , Hong-You Zhu , Xiao-Guang Xie , Yi Jin , Jun Lin
      The inclusion complexes of cordycepin with cyclodextrins (CDs) were prepared, the resultant complexes were characterised by UV–vis, FTIR, DSC, SEM, XRD, ESI-MS and proton nuclear magnetic resonance spectroscopy (1H NMR). The stoichiometry was established using a Job plot and the inclusion mechanism was clarified using molecular dynamic simulations. Molecular modelling calculations have been carried out to rationalise the experimental findings and predict the stable molecular structure of the inclusion complex. The stability of the inclusion complexes were confirmed by energetic and thermodynamic properties (ΔE, ΔH, ΔG and ΔS) and HOMO, LUMO orbital. The 1:1 binding model of complexes were visually proved by ESI-MS experiment. Our results showed that the purine group of cordycepin molecule was deeply inserted into the cavity of CDs.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structural features of a novel polysaccharide isolated from a New Zealand
           Maori mushroom Iliodiction cibarium
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Lu Ren , Patrick J.B. Edwards , Conrad O. Perera , Yacine Hemar
      A purified water-soluble fraction (ICP5) of a polysaccharide, isolated from a local Maori mushroom Iliodiction cibarium in New Zealand, was investigated for its structural properties. Size exclusion chromatography and dynamic light scattering showed that ICP5 had a large MW of 1.6×105 Da with a hydrodynamic diameter of 83±8 nm. Particle size measurements also displayed the tendency of ICP5 to aggregate when suspended in water. The results of GC–MS, FTIR and NMR analyses allowed some characteristics of the chemical structure of ICP5 to be determined. GC–MS results showed that ICP5 contained only glucose (81.61%), galactose (12.90%) and mannose (5.49%) monomers. The characterized fragment structures of ICP5 were found to be dominantly consisting of uronic acids, which formed a backbone containing 1,4-β-d-GlcpA. A small amount of unsaturated uronic acid also appeared to be present.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Capsular polysaccharide conformations in pneumococcal serotypes 19F and
           19A
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Michelle M. Kuttel , Graham E. Jackson , Mpho Mafata , Neil Ravenscroft
      Streptococcus pneumoniae is a significant pathogen in children. Although the PCV7 pneumococcal conjugate vaccine has reduced pneumococcal disease, non-vaccine serotype 19A infection has increased, despite expectations of cross-protection from vaccine serotype 19F. Serotype 19A is included in the new PCV13 vaccine, but not in PCV10. In the solution simulations of 19F and 19A oligosaccharide chains reported here, both polysaccharides form unstructured random coils, with inflexible repeat units linked by mobile phosphodiester linkages. However, there are clear conformational differences. In the 19F repeat unit, the rhamnose residue is nearly orthogonal to the other residues, whereas 19A has residues in similar orientations. This finding is corroborated by key inter-residue distances calculated from NMR NOESY experiments. Further, 19F is predominantly in extended conformations, whereas 19A exhibits a high prevalence of tight hairpin bends. These conformational differences may account for a lack of antibody cross-protection between serotypes 19F and 19A.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Quantitative characterization of hydration state and destructuring effect
           of monosaccharides and disaccharides on water hydrogen bond network
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): K. Shiraga , T. Suzuki , N. Kondo , J. De Baerdemaeker , Y. Ogawa
      Terahertz time-domain attenuated total reflection measurements of monosaccharide (glucose and fructose) and disaccharide (sucrose and trehalose) solutions from 0.146 M to 1.462 M were performed to evaluate (1) the hydration state and (2) the destructuring effect of saccharide solutes on the hydrogen bond (HB) network. Firstly, the extent of hydration water was determined by the decreased amount of bulk water with picosecond relaxation time that was replaced by that with much longer orientational relaxation time. As a result, we found glucose and trehalose exhibits stronger hydration capacity than fructose and sucrose, respectively, despite of the same number of the hydroxyl groups. For each saccharide, the hydration number tended to decrease with solute concentration. Secondly, the destructuring effect of these saccharide solutes on the HB network of the surrounding bulk water was discussed from the perspective of the fraction of non-hydrogen-bonded (NHB) water isolated from the HB network. We found the fraction of NHB water molecules that are not engaged in the HB network monotonously increased with saccharide concentration, indicating saccharide solutes promote the disruption of the water HB network. However, no noticeable differences were confirmed in the fraction of NHB water between glucose and fructose or between sucrose and trehalose. In contrast to hydration number, the number of NHB water produced by a single saccharide solute was less dependent on solute concentration, and three monosaccharide/disaccharide solutes were found to produce one/two NHB water molecules.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Synthetic study of 3-fluorinated sialic acid derivatives
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Katsuhiko Suzuki , Shusaku Daikoku , Sang-Hyun Son , Yukishige Ito , Osamu Kanie
      Sialic acid derivatives, analogs, and their conjugates are expected to be pharmaceutical candidates such as anti-influenza drugs and also useful probes for investigating the biological role of glycoconjugates. Derivatives of 3-fluorinated sialic acid (3-F-Sia) have been found to be excellent probes in investigating functions and mechanisms of a series of proteins. Here, we describe the syntheses of 3-F-Sia derivatives, which are useful in making biologically important conjugate probes. A practical method for the construction of 3-fluorinated sialosides based on the stereoselective formation of the corresponding anomeric O-trimethylsilyl ether and their nucleophilic attack by an alkyl halide, an allyl halide in particular, was developed. In addition, details of the synthesis of cytidine monophosphate (CMP)-3-F-Sia bearing a fluorescent tag, which has been proven to show dual functions as a substrate of CMP-sialic acid transporter (CST) and an inhibitor of sialyltransferase (STase), are described.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Functional glycolipid-crown-ethers by click chemistry
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Abbas Abdulameer Salman , Mojtaba Tabandeh , Thorsten Heidelberg , Rusnah Syahila Duali Hussen
      A series of glycolipid crown ether analogs was prepared by bis-propargylation of lauryl glycoside followed by subsequent click-coupling with ethylene glycol-based diazides. The triazole-linked macrocycles were obtained in remarkable high yields. While the surfactant assembly was affected by presence of sodium ions, suggesting the formation of complexes, no ion-selectivity was observed for the macrocylic ligands. Computational studies suggest a low but significant cation-binding activity of the macrocycle, involving coordination at both oxygen and nitrogen atoms.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Chemical synthesis of the tetrasaccharide repeating unit of the
           O-polysaccharide isolated from Azospirillum brasilense SR80
    • Abstract: Publication date: 10 April 2015
      Source:Carbohydrate Research, Volume 406
      Author(s): Vikramjit Sarkar , Balaram Mukhopadhyay
      A linear strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-polysaccharide from Azospirillum brasilense SR80. Stepwise glycosylation of the rationally protected thioglycoside donors activated by NIS in the presence of La(OTf)3 furnished the target tetrasaccharide. The glycosylation reactions resulted in the formation of the desired linkage with absolute stereoselectivity and afforded the required derivatives in good to excellent yields. The phthalimido group has been used as the precursor of the desired acetamido group to meet the requirement of 1,2-trans glycosidic linkage.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Editorial board
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404




      PubDate: 2015-03-01T16:48:40Z
       
  • Graphical contents list
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404




      PubDate: 2015-03-01T16:48:40Z
       
  • Synthesis of a new glycosphingolipid, neurosporaside, from Neurospora
           crassa
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Isao Ohtsuka , Noriyasu Hada , Misaki Kanemaru , Takanari Fujii , Toshiyuki Atsumi , Nobuko Kakiuchi
      The glycosphingolipid neurosporaside (α-d-Glcp-(1→2)-β-d-Galp-(1→6)-β-d-Galp-(1→6)-β-d-Galp-(1→)-Cer) occurs in Neurospora crassa. We attempted to synthesize neurosporaside by block synthesis (route A) and linear synthesis (route B). Oligosaccharide derivatives were synthesized using trimethylsilyltrifluoromethanesulfonate and N-iodosuccinimide/trifluoromethane sulfonic acid as promoters. The target tetrasaccharide could not be attained via route A, but route B showed potential: glycosidic bonds (β-d-Galp-(1→6)-β-d-Galp-(1→6)-β-d-Galp) were formed stereoselectively, leading to the synthesis of glycosphingolipid 2.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Synthesis of two β-cyclodextrin derivatives containing a vinyl group
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Yong-Fu Li , Yi-Ming Ha , Qin Guo , Qing-Peng Li
      β-CD maleate (CDM) and β-CD itaconate (CDI) were prepared by esterification of β-cyclodextrin (β-CD) with maleic acid and itaconic acid using phosphate as a catalyst in a semi-dry process. The esterification of β-CD was carried out using [Itaconic acid ] or [Maleic acid ] 4mol/mol of CD; M/L ratio 1:0.6; temperature 110°C; [4-methoxyphenol] 2.5% amount of acid; reaction time 3.5h. The esterification rates of CDM and CDI are 70.38% and 21.02%, respectively. We found that CDM and CDI were both monoesters. Here, we also established a new evaluation method for the rate of esterification.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Modular modification of xylan with UV-initiated thiol-ene reaction
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Leena Nurmi , Reeta Salminen , Harri Setälä
      Birch xylan was functionalized with various thiols through UV initiated radical thiol-ene reaction under mild conditions. Xylan was allylated through etherification with allyl glycidyl ether under alkaline conditions. The allylated xylan was then reacted with thiols containing varying functional groups: trimethylbenzyl mercaptan, dodecanethiol, thioglycolic acid, l-cysteine and cysteamine hydrochloride. The reactions were conducted under homogeneous conditions at room temperature, either in water (hydrophilic thiols) or in DMF (hydrophobic thiols). The effect of reaction parameters to the functionalization efficiency was studied, including, for example, thiol excess, thiol character, initiator amount and reaction mixture concentration. The reactions were fast and 100% conversion of allyl groups was reached in most cases, sometimes already within 10min. Water as solvent resulted generally in faster reactions when compared to DMF, and it was possible to conduct the aqueous reaction even without added UV initiator. It was also possible to incorporate two functionalities simultaneously during one reaction into the xylan structure.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • New sugar-derived bifunctional chiral ureas as highly effective
           organocatalysts in asymmetric aza-Henry reaction
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Jolanta Robak , Bogusław Kryczka , Barbara Świerczyńska , Anna Zawisza , Stanisław Porwański
      A simple synthesis of series of new catalysts derived from chiral bifunctional ureas is described. The aza-Henry reaction of imines with nitromethane was promoted by sugar derived bifunctional organocatalysts to give optically active β-nitroamines. The aza-Henry reaction products were obtained in good yields (35–98%) and ee up to 99%.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Efficient synthesis of O-antigen fragments expressed by Burkholderia
           anthina by modular synthesis approach
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Inga Nilsson , Dirk Michalik , Alba Silipo , Antonio Molinaro , Christian Vogel
      To facilitate mapping of the interaction region of the O-chain of the lipopolysaccharide from Burkholderia anthina and of a lipopolysaccharide-specific monoclonal antibody, trisaccharide propyl α-l-rhamnopyranosyl-(1→2)-α-d-galactopyranosyl-(1→3)-α-l-rhamnopyranoside (27) and hexasaccharide propyl α-l-rhamnopyranosyl-(1→2)-α-d-galactopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-rhamnopyranosyl-(1→2)-α-d-galactopyranosyl-(1→3)-α-l-rhamnopyranoside (33) were synthesized. These oligosaccharides represent the repeating monomer and dimer of the O-antigen, respectively.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Structural insights into alginate binding by bacterial cell-surface
           protein
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Kanate Temtrirath , Kousaku Murata , Wataru Hashimoto
      A gram-negative Sphingomonas sp. strain A1 inducibly forms a mouth-like pit on the cell surface in the presence of alginate and directly incorporates polymers into the cytoplasm via the pit and ABC transporter. Among the bacterial proteins involved in import of alginate, a cell-surface EfeO-like Algp7 shows an ability to bind alginate, suggesting its contribution to accumulate alginate in the pit. Here, we show identification of its positively charged cluster involved in alginate binding using X-ray crystallography, docking simulation, and site-directed mutagenesis. The tertiary structure of Algp7 was determined at a high resolution (1.99Å) by molecular replacement, although no alginates were included in the structure. Thus, an in silico model of Algp7/oligoalginate was constructed by docking simulation using atomic coordinates of Algp7 and alginate oligosaccharides, where some charged residues were found to be potential candidates for alginate binding. Site-directed mutagenesis was conducted and five purified mutants K68A, K69A, E194A, N221A, and K68A/K69A were subjected to a binding assay. UV absorption difference spectroscopy along with differential scanning fluorimetry analysis indicated that K68A/K69A exhibited a significant reduction in binding affinity with alginate than wild-type Algp7. Based on these data, Lys68/Lys69 residues of Algp7 probably play an important role in binding alginate.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Acceptor-induced modification of regioselectivity in CGTase-catalyzed
           glycosylations of p-nitrophenyl-glucopyranosides
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Simon Strompen , Alfonso Miranda-Molina , Agustín López-Munguía , Edmundo Castillo , Gloria Saab-Rincón
      Cyclodextrin glycosyltransferases (CGTase) are reported to selectively catalyze α(1→4)-glycosyl transfer reactions besides showing low hydrolytic activity. Here, the effect of the anomeric configuration of the glycosyl acceptor on the regioselectivity of CGTase catalyzed glycosylations was investigated. For this purpose, the α and β anomers of p-nitrophenyl-d-glucopyranoside were used as glycosyl acceptors, Bacillus macerans and Thermoanaerobacter sp. CGTases were used as biocatalysts and β-cyclodextrin as the glycosyl donor. As expected, p-nitrophenyl-α-d-glucopyranosyl-(1→4)-O-α-d-glucopyranoside was produced when p-nitrophenyl-α-d-glucopyranoside was used as acceptor with B. macerans CGTase. Surprisingly, when p-nitrophenyl-β-d-glucopyranoside was used as glycosyl acceptor, besides the expected α(1→4)-glycosylation products both α(1→3)- and α(1→6)-transfer products were also obtained. This unexpected change in B. macerans CGTase regioselectivity leading to α(1→4)-, α(1→3)- and α(1→6)-glycosylation products was also observed for Thermoanaerobacter sp. CGTase with the β anomer. It is shown, applying time course analyses, that all isomers can be synthesized efficiently by adequate selection of enzyme and reaction conditions. In fact, when using Thermoanaerobacter sp. CGTase the yield of p-nitrophenyl-β-d-isomaltoside (the α(1→6)-transfer product) was the highest at long reaction time (19% yield). The previously unknown capacity of α(1→6)-glycosidic linkages formation by CGTases demonstrates an unexpected broader regioselectivity of CGTases in glycosyl-transfer reactions as well as an acceptor dependent transfer selectivity.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Identification of novel isomeric pectic oligosaccharides using hydrophilic
           interaction chromatography coupled to traveling-wave ion mobility mass
           spectrometry
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Antonius G.M. Leijdekkers , Jie-Hong Huang , Edwin J. Bakx , Harry Gruppen , Henk A. Schols
      Separation and characterization of complex mixtures of pectic oligosaccharides still remains challenging and often requires the use of multiple analytical techniques, especially when isomeric structures are present. In this work, it is demonstrated that the coupling of hydrophilic interaction chromatography (HILIC) to traveling-wave ion mobility mass spectrometry (TWIMMS) enabled the simultaneous separation and characterization of complex mixtures of various isomeric pectic oligosaccharides. Labeling of oligosaccharides with 3-aminoquinoline (3-AQ) improved MS-ionization efficiency of the oligosaccharides and reduced the complexity of the product ion mass spectra, without losing resolution of the HILIC separation. In addition, labeling enabled quantification of oligosaccharides on molar basis using in-line fluorescence detection. Isomeric structures were distinguished using TWIMMS. The 3-AQ-HILIC–TWIMMS method was used to characterize a series of isomeric sugar beet rhamnogalacturonan I derived oligosaccharides carrying a glucuronic acid substituent. Thereby, some novel structural features were identified for the first time: glucuronic acid was attached to O-3 or to O-2 of galacturonic acid residues and a single galacturonic acid residue within an oligomer could contain both an acetyl group and a glucuronic acid substituent.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Triterpenoid saponins from Albizia lebbeck (L.) Benth and their inhibitory
           effect on the survival of high grade human brain tumor cells
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Olivier Placide Noté , Dong Jihu , Cyril Antheaume , Maria Zeniou , Dieudonné Emmanuel Pegnyemb , Dominique Guillaume , Hervé Chneiwess , Marie Claude Kilhoffer , Annelise Lobstein
      As part of our search of new bioactive triterpenoid saponins from Cameroonian Mimosaceae plants, phytochemical investigation of the roots of Albizia lebbeck led to the isolation of two new oleanane-type saponins, named lebbeckosides A–B (1–2). Their structures were established on the basis of extensive 1D and 2D NMR (1H, 13C NMR, DEPT, COSY, TOCSY, ROESY, HSQC, and HMBC) and HRESIMS studies, and by chemical evidence. Compounds 1–2 were evaluated for their inhibitory effect on the metabolism of high grade human brain tumor cells, the human glioblastoma U-87 MG cell lines and the glioblastoma stem-like TG1 cells isolated from a patient tumor, and known to be particularly resistant to standard therapies. The isolated saponins showed significant cytotoxic activity against U-87 MG and TG1 cancer cells with IC50 values of 3.46μM and 1.36μM for 1, and 2.10μM and 2.24μM for 2, respectively.
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      PubDate: 2015-03-01T16:48:40Z
       
  • One-pot catalytic conversion of cellulose into polyols with Pt/CNTs
           catalysts
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Li Yang , Xiaopei Yan , Qiwu Wang , Qiong Wang , Haian Xia
      A series of Pt nanoparticles supported on carbon nanotubes (CNTs) were synthesized using the incipient-wetness impregnation method. These catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM) techniques. The characterization results indicate that the Pt nanoparticles were highly dispersed on the surface of the CNTs, and the mean size was less than 5nm. These catalysts were utilized to convert cellulose to hexitol, ethylene glycerol (EG), and 1,2-propylene glycol (1,2-PG) under low H2 pressure. The total yields were as high as 71.4% for EG and 1,2-PG using 1Pt/CNTs as the catalyst in the hydrolytic hydrogenation of cellulose under mild reaction conditions.
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      PubDate: 2015-03-01T16:48:40Z
       
  • DFT application in conformational determination of cellobiose
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Shihai Yan , Lishan Yao
      The potential energy of β-cellobiose in water, as a function of the H1′C1′O′C4 (ϕ) and C1′O′C4H4 (ψ) dihedral angles, is investigated using DFT methods and three energy minima (syn-ϕ/syn-ψ, anti-ϕ/syn-ψ, and syn-ϕ/anti-ψ) are identified. It is found that the hydrogen bonding and the H…H repulsion are vital for the energy variation of cellobiose. The geometry structure varies significantly when cellobiose is surrounded by 52 water molecules. NMR chemical shift calculations suggest that the C4 (C1′) chemical shifts (δ) are sensitive to the conformational changes, with the values of 80.4ppm (103.3ppm) at syn-ϕ/syn-ψ, 70.0ppm (98.9ppm) at anti-ϕ/syn-ψ, and 75.6ppm (95.3ppm) at syn-ϕ/anti-ψ. The chemical shifts detection of characteristic positions is helpful for the determination of conformations, especially for those with equivalent energies. The chemical shielding tensor analysis shows that for C1′, the directions and amplitudes of two shielding components (σ22 and σ33) vary distinctly with ϕ and ψ whereas for C4, σ33 of C4 remains unchanged, but σ22 varies by 13 (26) ppm from syn-ϕ/syn-ψ to anti-ϕ/syn-ψ (syn-ϕ/anti-ψ). The distinctive C4 and C1′ chemical shifts at different conformations suggest that they can be useful in (ϕ, ψ) dihedral angle determinations.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Structural and genetic relationships of closely related O-antigens of
           Cronobacter spp. and Escherichia coli: C. sakazakii G2594 (serotype O4)/E.
           coli O103 and C. malonaticus G3864 (serotype O1)/E. coli O29
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Alexander S. Shashkov , Min Wang , Eldar M. Turdymuratov , Shaohui Hu , Nikolay P. Arbatsky , Xi Guo , Lei Wang , Yuriy A. Knirel
      O-Antigen (O-polysaccharide) variation is the basis for bacterial serotyping and is important in bacterial virulence and niche adaptation. In this work, we present structural and genetic evidences for close relationships between the O-antigens of the Cronobacter spp. and Escherichia coli. Cronobacter sakazakii G2594 (serotype O4) and Cronobacter malonaticus G3864 (serotype O1) are structurally related to those of E. coli O103 and O29, respectively, and some other members of the Enterobacteriaceae family differing in the patterns of lateral glucosylation (C. sakazakii G2594) or O-acetylation (C. malonaticus G3864). The O-antigen gene clusters of the corresponding Cronobacter and E. coli strains contain the same genes with high-level similarity, and the structural differences within both O-antigen pairs were suggested to be due to modification genes carried by prophages.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Related structures of the O-polysaccharides of Cronobacter dublinensis
           G3983 and G3977 containing
           3-(N-acetyl-l-alanyl)amino-3,6-dideoxy-d-galactose
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Nikolay P. Arbatsky , Min Wang , Eldar M. Turdymuratov , Shaohui Hu , Alexander S. Shashkov , Lei Wang , Yuriy A. Knirel
      Cronobacter spp. are emerging opportunistic human pathogens linked with life-threatening infections predominantly in neonates. O-Antigen (O-polysaccharide) is highly variable and plays an important role in virulence and niche adaptation. In this work, short-chain O-polysaccharides consisting on the average of 2–3 repeating units were obtained by mild acid or mild alkaline degradation of the lipopolysaccharides of C. dublinensis G3983 and G3977 and studied by composition analysis, Smith degradation, and 1H and 13C NMR spectroscopy. The following structures of the O-polysaccharides were established: where R indicates H in strain G3983 or α-d-Glcp in strain G3977, d-Fuc3NAlaAc indicates 3-(N-acetyl-l-alanyl)amino-3,6-dideoxy-d-galactose. Both strains share the O-antigen gene cluster, which is identical to that of C. dublinensis O1 (Foodborne Pathog. Dis. 2013, 10, 343–352). The assigned gene functions are in agreement with the O-antigen structure of C. dublinensis G3983, and the side-chain glucosylation of the O-antigen of C. dublinensis G3977 is evidently encoded elsewhere in the genome.
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      PubDate: 2015-03-01T16:48:40Z
       
  • Structural and genetic studies of the O-antigen of Escherichia coli O163
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Andrei V. Perepelov , Quan Wang , Sof’ya N. Senchenkova , Ye Qian , Alexander S. Shashkov , Lei Wang , Yuriy A. Knirel
      An acidic O-polysaccharide (O-antigen) of Escherichia coli O163 was obtained by mild acid hydrolysis of the lipopolysaccharide and studied by sugar analysis and Smith degradation along with 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the linear tetrasaccharide repeating unit was established, which is unique among known structures of bacterial polysaccharides: Functions of genes in the O-antigen gene cluster of E. coli O163 were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the O-polysaccharide structure. Relationships between O-antigen structures and gene clusters of E. coli O163 and Salmonella enterica O41 are discussed.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structure of the capsular polysaccharide of Acinetobacter baumannii 1053
           having the KL91 capsule biosynthesis gene locus
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Alexander S. Shashkov , Mikhail M. Shneider , Sof’ya N. Senchenkova , Anastasiya V. Popova , Anastasia S. Nikitina , Vladislav V. Babenko , Elena S. Kostryukova , Konstantin A. Miroshnikov , Nikolay V. Volozhantsev , Yuriy A. Knirel
      Acinetobacter baumannii 1053 is the type strain for the maintenance of specific bacteriophage AP22, which infects a fairly broad range of A. baumannii strains circulating in Russian clinics and hospitals. A capsular polysaccharide (CPS) was isolated from cells of strain 1053 and studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit was established: where ManNAcA and FucNAc indicate 2-acetamido-2-deoxymannuronic acid and 2-acetamido-2,6-dideoxygalactose, respectively. A polysaccharide having the same repeating unit but a shorter chain was isolated by the phenol–water extraction of bacterial cells. Sequencing of the CPS biosynthesis gene locus showed that A. baumannii 1053 belongs to a new group designated KL91. The gene functions assigned putatively by a comparison with available databases were in agreement with the CPS structure established.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structure of the O-specific polysaccharides from planktonic and biofilm
           cultures of Pseudomonas chlororaphis 449
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Evelina L. Zdorovenko , Alexander S. Shashkov , Marina V. Zhurina , Vladimir K. Plakunov , Yuriy A. Knirel
      O-Specific polysaccharides were obtained from the lipopolysaccharides isolated from the planktonic and biofilm cultures of Pseudomonas chlororaphis 449 and studied by composition analysis and 1D and 2D 1H and 13C NMR spectroscopy. The following structure was established: where the degree of non-stoichiometric 6-O-acetylation of GalNAc is ∼60% in the planktonic form or ∼10% in biofilm.
      Graphical abstract image Highlights

      PubDate: 2015-03-01T16:48:40Z
       
  • Cholesteryl and diosgenyl glycosteroids: synthesis and characterization of
           new smectic liquid crystals
    • Abstract: Publication date: 2 March 2015
      Source:Carbohydrate Research, Volume 404
      Author(s): Rémi Beaulieu , Sébastien Gottis , Claire Meyer , Eric Grand , Virginie Deveaux , José Kovensky , Imane Stasik
      While present in large numbers in nature, studies on the physical chemical aspects of glycosteroids are quite rare and focused on cholesterol, and all compounds studied thus far have shown liquid crystalline properties in a narrow temperature range. New glycosteroids composed by cholesterol or diosgenin and different glycosidic moieties have been synthesized here in order to analyze the influence of the structure on the formation of mesophases. These compounds have been studied by crossed polarized optical microscopy. These studies have revealed that these new glycosteroids form Smetic A liquid crystals in a broad temperature range.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Common side reactions of the glycosyl donor in chemical glycosylation
    • Abstract: Publication date: Available online 25 February 2015
      Source:Carbohydrate Research
      Author(s): Helle M. Christensen , Stefan Oscarson , Henrik H. Jensen
      Chemical glycosylation is central to carbohydrate chemistry and is generally recognised as a challenging reaction. This review describes the most described side reactions of glycosyl donors in glycosylation and how scientists have attempted to explain their observations and in some cases succeeded in solving a particular encountered problem. The topics covered are donor hydrolysis, elimination to form glycals, intermolecular aglycon transfer of thioglycosides and glycosyl imidate rearrangement.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • Structure of a new pseudaminic acid-containing capsular polysaccharide of
           Acinetobacter baumannii LUH5550 having the KL42 capsule biosynthesis locus
           
    • Abstract: Publication date: Available online 23 February 2015
      Source:Carbohydrate Research
      Author(s): Sof’ya N. Senchenkova , Anastasiya V. Popova , Alexander S. Shashkov , Mikhail M. Shneider , Zhu Mei , Nikolay P. Arbatsky , Bin Liu , Konstantin A. Miroshnikov , Nikolay V. Volozhantsev , Yuriy A. Knirel
      The capsular polysaccharide from Acinetobacter baumannii LUH5550 was studied by 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the branched trisaccharide repeating unit was established: where Pse5Ac7RHb indicates 5-acetamido-3,5,7,9-tetradeoxy-7-[(R)-3-hydroxybutanoylamino]-l-glycero-l-manno-non-2-ulosonic acid. The genes in the capsule biosynthesis locus designated KL42 are consistent with the structure established.
      Graphical abstract image

      PubDate: 2015-03-01T16:48:40Z
       
  • 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: 2015-02-13T06:44:34Z
       
  • Enzymatic synthesis of nucleobase-modified UDP-sugars: scope and
           limitations
    • 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: 2015-02-07T20:30:09Z
       
  • 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: 2015-02-07T20:30:09Z
       
 
 
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