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  Subjects -> CHEMISTRY (Total: 846 journals)
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    - CHEMISTRY (599 journals)
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CHEMISTRY (599 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 6)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 25)
ACS Catalysis     Full-text available via subscription   (Followers: 30)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 24)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 36)
ACS Nano     Full-text available via subscription   (Followers: 206)
ACS Photonics     Full-text available via subscription   (Followers: 9)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 4)
Advanced Functional Materials     Hybrid Journal   (Followers: 45)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 12)
Advances in Chemistry     Open Access   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
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: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 10)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 24)
American Journal of Plant Physiology     Open Access   (Followers: 12)
American Mineralogist     Full-text available via subscription   (Followers: 12)
Analyst     Full-text available via subscription   (Followers: 44)
Angewandte Chemie     Hybrid Journal   (Followers: 144)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 203)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 23)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemistry     Full-text available via subscription   (Followers: 261)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 114)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 103)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 1)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 8)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 65)
Catalysis for Sustainable Energy     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
Cellulose     Hybrid Journal   (Followers: 5)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 71)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 21)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 18)
Chemical Reviews     Full-text available via subscription   (Followers: 160)
Chemical Science     Open Access   (Followers: 20)
Chemical Technology     Open Access   (Followers: 15)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry - A European Journal     Hybrid Journal   (Followers: 129)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 16)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 8)
Chemistry International     Hybrid Journal   (Followers: 1)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 174)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 1)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 3)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 8)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 15)
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Current Science     Open Access   (Followers: 47)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
Elements     Full-text available via subscription   (Followers: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 6)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 3)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 4)
Environmental Science : Nano     Partially Free   (Followers: 1)
Environmental Toxicology & Chemistry     Hybrid Journal   (Followers: 18)

        1 2 3 | Last

Journal Cover Carbohydrate Research
  [SJR: 0.612]   [H-I: 98]   [26 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
   Published by Elsevier Homepage  [3041 journals]
  • On the formation and role of reactive oxygen species in light-driven LPMO
           oxidation of phosphoric acid swollen cellulose
    • Abstract: Publication date: Available online 18 March 2017
      Source:Carbohydrate Research
      Author(s): K.B. Möllers, H. Mikkelsen, T.I. Simonsen, D. Cannella, K.S. Johansen, M.J. Bjerrum, C. Felby
      Light-driven activation of lytic polysaccharide monooxygenases (LPMOs) has been attributed to the transfer of high redox potential electrons from excited photopigments to the enzyme. However, due to the formation of reactive oxygen species (ROS) in such a system, not only electrons from the pigments but also ROS could be part of the enzyme mechanism. This work investigates the role of ROS in the oxidation of phosphoric acid swollen cellulose (PASC) by a light-driven LPMO system. Our results clearly show that the addition of superoxide dismutase or catalase to remove ROS did not attenuate the capacity of the light-driven LPMO system to oxidize PASC, as measured by formation of oxidized oligosaccharides. We conclude that ROS are not part of the light-driven LPMO activation; hence, transfer of high redox potential electrons from the excited photopigment to the LPMO remains the most likely mechanism under the conditions tested in this study.
      Graphical abstract image

      PubDate: 2017-03-18T16:40:12Z
       
  • Heterologous expression, purification and characterization of three novel
           esterases secreted by the lignocellulolytic fungus Penicillium
           purpurogenum when grown on sugar beet pulp
    • Abstract: Publication date: Available online 18 March 2017
      Source:Carbohydrate Research
      Author(s): Gabriela Oleas, Eduardo Callegari, Romina Sepúlveda, Jaime Eyzaguirre
      The lignocellulolytic fungus, Penicillium purpurogenum, grows on a variety of natural carbon sources, among them sugar beet pulp. Culture supernatants of P. purpurogenum grown on sugar beet pulp were partially purified and the fractions obtained analyzed for esterase activity by zymograms. The bands with activity on methyl umbelliferyl acetate were subjected to mass spectrometry to identify peptides. The peptides obtained were probed against the proteins deduced from the genome sequence of P. purpurogenum. Eight putative esterases thus identified were chosen for future work. Their cDNAs were expressed in Pichia pastoris. The supernatants of the recombinant clones were assayed for esterase activity, and five of the proteins were active against one or more substrates: methyl umbelliferyl acetate, indoxyl acetate, methyl esterified pectin and fluorescein diacetate. Three of those enzymes were purified, further characterized and subjected to a BLAST search. Based on their amino acid sequence and properties, they were identified as follows: RAE1, pectin acetyl esterase (CAZy family CE 12); FAEA, feruloyl esterase (could not be assigned to a CAZy family) and EAN, acetyl esterase (former CAZy family CE 10).
      Graphical abstract image

      PubDate: 2017-03-18T16:40:12Z
       
  • Structural elucidation of a novel transglycosylated compound α-glucosyl
           rhoifolin and of α -glucosyl rutin by NMR spectroscopy
    • Abstract: Publication date: Available online 16 March 2017
      Source:Carbohydrate Research
      Author(s): Chisa Aoki, Yoshihiro Takeuchi, Kenjirou Higashi, Yuta Okamoto, Akihito Nakanishi, Mahamadou Tandia, Jun Uzawa, Keisuke Ueda, Kunikazu Moribe
      We report the full assignment of 1H and 13C NMR signals belonging to α-glucosyl rhoifolin (Rhf-G), a novel transglycosylated compound synthesized from a flavone glycoside, rhoifolin, as well as its chemical structure. Furthermore, we report the complete NMR signal assignment for another transglycosylated compound, α-glucosyl rutin (Rutin-G), as the signals corresponding to its sugar moieties had not been identified. Electrospray ionization-mass spectrometry along with multiple NMR methods revealed that Rhf-G possesses three sugar moieties in its chemical structure. The additional glucose was bound directly via a transglycosylation to rhoifolin at position 3a of the sugar moiety. Interestingly, intramolecular hydrogen bonds in the basic Rhf-G and Rutin-G skeletons were confirmed by HMBC experiments. These findings will be helpful for comprehensive NMR studies on transglycosylated compounds in food, cosmetic, and pharmaceutical fields.
      Graphical abstract image

      PubDate: 2017-03-18T16:40:12Z
       
  • Synthesis and conformational analysis of a simplified inositol-model of
           the Streptococcus pneumoniae 19F capsular polysaccharide repeating unit
    • Abstract: Publication date: Available online 14 March 2017
      Source:Carbohydrate Research
      Author(s): Giorgio Catelani, Felicia D'Andrea, Lorenzo Guazzelli, Alessio Griselli, Nicola Testi, Maria Assunta Chiacchio, Laura Legnani, Lucio Toma
      Carbohydrate mimics have been studied for a long time as useful sugar substitutes, both in the investigation of biological events and in the treatment of sugar-related diseases. Here we report further evaluation of the capabilities of inositols as carbohydrate substitutes. The conformational features of an inositol-model of a simplified repeating unit corresponding to the capsular polysaccharide of Streptococcus pneumoniae 19F has been evaluated by computational analysis, and compared to the native repeating unit. The inositol mimic was synthesized, and its experimental spectroscopic data allowed for verification of the theoretical results.
      Graphical abstract image

      PubDate: 2017-03-15T16:35:07Z
       
  • N-Substituted 5-amino-1-hydroxymethyl-cyclopentanetriols: A new family of
           activity promotors for a GM1-gangliosidosis related human lysosomal
           β-galactosidase mutant
    • Abstract: Publication date: Available online 11 March 2017
      Source:Carbohydrate Research
      Author(s): Michael Schalli, Christina Tysoe, Roland Fischer, Bettina M. Pabst, Martin Thonhofer, Eduard Paschke, Tanja Rappitsch, Arnold E. Stütz, Marion Tschernutter, Werner Windischhofer, Stephen G. Withers
      From 1,2;3,4-di-O-isopropylidene-α-D-galactopyranose, a series of highly functionalized (hydroxymethyl)cyclopentanes was easily available. In line with reports by Reymond and Jäger on similar structures, these amine containing basic carbasugars are potent inhibitors of β-D-galactosidases and, for the first time, could be shown to act as pharmacological chaperones for GM1-gangliosidosis-associated lysosomal acid β-galactosidase mutant R201C, thus representing a new structural type of pharmacological chaperones for this lysosomal storage disease.
      Graphical abstract image

      PubDate: 2017-03-15T16:35:07Z
       
  • Stereoselective acetylation of hemicellulosic C5-sugars
    • Abstract: Publication date: Available online 10 March 2017
      Source:Carbohydrate Research
      Author(s): Zachary D. Herde, Prathap John, Dania Alvarez-Fonseca, Jagannadh Satyavolu, Christopher T. Burns
      The stereoselective peracetylation of α-D-xylose (1) and α-L-arabinose (4) using a combination of triethylamine and acetic anhydride in the presence or absence of a catalytic amount of dimethylaminopyridine (DMAP) is described. The peracetylated D-xylose and L-arabinose alpha pyranose anomers 2α and 5α are obtained in 97% and 56% yields respectively. The peracetylated D-xylose beta pyranose anomer 2β is obtained in 71% yield through simple modification of the reaction conditions. Details regarding synthesis and isolation optimization studies under different conditions are presented below. The stereoselective peracetylation reactions disclosed here have been used to separate mixtures of D-xylose and L-arabinose as their peracetylated derivatives 2β and 5α in 47% and 42% yields and can provide pure pentoses after deacetylation.
      Graphical abstract image

      PubDate: 2017-03-15T16:35:07Z
       
  • A Morita-Baylis-Hillman based route to C-5a-chain-extended
           4-epi-isofagomine type glycosidase inhibitors
    • Abstract: Publication date: Available online 6 March 2017
      Source:Carbohydrate Research
      Author(s): René Lebl, Martin Thonhofer, Christina Tysoe, Bettina M. Pabst, Michael Schalli, Patrick Weber, Eduard Paschke, Arnold E. Stütz, Marion Tschernutter, Werner Windischhofer, Stephen G. Withers
      By Morita-Baylis-Hillman reaction of 2,3-O-isopropylidene-D-glyceraldehyde with α,β-unsaturated carbonyl as well as hetero analogous carbonyl compounds such as acrylonitrile, suitable precursors of isofagomine and of 4-epi-isofagomine are available. Elaboration of the structures by amine introduction, followed by intramolecular ring closure and subsequent hydroboration of the double bond provides 4-epi-isofagomine derivatives featuring chain extensions at C-5a which are determined by the structures of the carbonyl compounds employed. As an example, the synthesis of C-(5aR)- and C-(5aS)-5a-C-pentyl-4-epi-isofagomines, powerful inhibitors of β-galactosidases, is outlined. In line with reported data, the (C-5aR) epimer was found a highly potent experimental pharmacological chaperone for GM1-associated human lysosomal β-galactosidase mutant R201C.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Synthesis and biological activities of C-glycosides of KRN 7000 with novel
           ceramide residues
    • Abstract: Publication date: Available online 6 March 2017
      Source:Carbohydrate Research
      Author(s): Ahmad S. Altiti, Xiaojing Ma, Lixing Zhang, Yi Ban, Richard W. Franck, David R. Mootoo
      The identification of immunoactive agents for clinical and mechanistic applications is a very active area of research. In this vein, analogues of the potent immunostimulant KRN 7000 with diverse cytokine profiles have attracted considerable attention. Herein, we report on the synthesis and activity for four new C-glycosides of KRN 7000, 11-phenylundecanoyl and 11-p-fluorophenylundecanoyl derivatives of C-KRN 7000, 2,3-bis-epi-C-KRN 7000 and the reverse amide of C-KRN 7000. In mice, compared to C-KRN 7000, 2,3-bis-epi-C-KRN 7000 stimulated higher release of the anti-inflammatory cytokine IL-4 and lower release of the inflammatory cytokines IFN-γ and IL-12. The phenyl terminated alkanoyl and reverse amide analogues were inactive. These data suggest that structure activity effects for KRN 7000 are not necessarily additive and their use in the design of new analogues will require an improved understanding of how subtle structural changes impact on cytokine activity.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Synthesis of a disaccharide repeating unit of the O-antigen from
           Burkholderia ambifaria and its oligomers
    • Abstract: Publication date: Available online 6 March 2017
      Source:Carbohydrate Research
      Author(s): Dongyue Wang, Weiwei Zhu-Ge, Zhongwu Guo, Guofeng Gu
      A disaccharide repeating unit of the O-antigen from Burkholderia ambifaria, 6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-O(CH2)3NH2 (1), and its dimer and trimer, 6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-(1 → 3)-6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-O(CH2)3NH2 (2) and 6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-(1 → 3)-6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-(1 → 3)-6-deoxy-β-D-Alt-(1 → 4)-α-D-Rha-O(CH2)3NH2 (3), were synthesized via a convergent strategy. The key disaccharyl thioglycoside 4 as a glycosyl donor was stereoselectively assembled by glycosylation of rhammnosyl acceptor 5 with 6-deoxy-altrosyl trichloroacetimidate donor 6b. The glycosidation of 4 with 3-azidopropanol followed by global deprotection afforded the target disaccharide 1. Further elongation of the carbohydrate chain of this glycosidation product with the disaccharyl donor 4 followed by global deprotection generated rapidly the dimeric tetrasaccharide 2 and the trimeric hexasaccharide 3 in a convergent [2 + 2] and [2 + 2 + 2] manner, respectively.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • RP-UHPLC-UV-ESI-MS/MS analysis of LPMO generated C4-oxidized
           
    • Abstract: Publication date: Available online 6 March 2017
      Source:Carbohydrate Research
      Author(s): Matthias Frommhagen, Gijs van Erven, Mark Sanders, Willem J.H. van Berkel, Mirjam A. Kabel, Harry Gruppen
      Lytic polysaccharide monooxygenases (LPMOs) are able to cleave recalcitrant polysaccharides, such as cellulose, by oxidizing the C1 and/or C4 atoms. The analysis of the resulting products requires a variety of analytical techniques. Up to now, these techniques mainly focused on the identification of non-oxidized and C1-oxidized oligosaccharides. The analysis of C4-oxidized gluco-oligosaccharides is mostly performed by using high pressure anion exchange chromatography (HPAEC). However, the alkaline conditions used during HPAEC analysis lead to tautomerization of C4-oxidized gluco-oligosaccharides, which limits the use of this technique. Here, we describe the use of reverse phase-ultra high performance liquid chromatography (RP-UHPLC) in combination with non-reductive 2-aminobenzamide (2-AB) labeling. Non-reductive 2-AB labeling enabled separation of C4-oxidized gluco-oligosaccharides from their non-oxidized counterparts. Moreover, RP-UHPLC does not require buffered mobile phases, which reduce mass spectrometry (MS) sensitivity. The latter is seen as an advantage over other techniques such as hydrophilic interaction liquid chromatography and porous graphitized carbon coupled to MS. RP-UHPLC coupled to UV detection and mass spectrometry allowed the identification of both labeled non-oxidized and C4-oxidized oligosaccharides. Non-reductive labeling kept the ketone at the C4-position of LPMO oxidized oligosaccharides intact, while selective reducing agents such as sodium triacetoxyborohydride (STAB) reduced this ketone group. Our results show that RP-UHPLC-UV-ESI-MS in combination with non-reductively 2-AB labeling is a suitable technique for the separation and identification of LPMO-generated C4-oxidized gluco-oligosaccharides.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Structural studies of Neurospora crassa LPMO9D and redox partner CDHIIA
           using neutron crystallography and small-angle scattering
    • Abstract: Publication date: Available online 4 March 2017
      Source:Carbohydrate Research
      Author(s): Annette M. Bodenheimer, William B. O'Dell, Christopher B. Stanley, Flora Meilleur
      Sensitivity to hydrogen/deuterium and lack of observable radiation damage makes cold neutrons an ideal probe for the structural studies of proteins with highly photosensitive groups such as the copper center of lytic polysaccharide monooxygenases (LPMOs) and flavin adenine dinucleotide (FAD) and heme redox cofactors of cellobiose dehydrogenases (CDHs). Here, neutron crystallography and small-angle neutron scattering are used to investigate Neurospora crassa LMPO9D (NcLPMO9D) and CDHIIA (NcCDHIIA), respectively. The presence of LPMO greatly enhances the efficiency of commercial glycoside hydrolase cocktails in the depolymerization of cellulose. LPMOs can receive electrons from CDHs to activate molecular dioxygen for the oxidation of cellulose resulting in chain cleavage and disruption of local crystallinity. Using neutron protein crystallography, the hydrogen/deuterium atoms of NcLPMO9D could be located throughout the structure. At the copper active site, the protonation states of the side chains of His1, His84, His157 and Tyr168, and the orientation of water molecules could be determined. Small-angle neutron scattering measurements provided low resolution models of NcCDHIIA with both the dehydrogenase and cytochrome domains in oxidized states that exhibited elongated conformations. This work demonstrates the suitability of neutron diffraction and scattering for characterizing enzymes critical to oxidative cellulose deconstruction.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Novel substrates for the automated and manual assay of
           endo-1,4-β-xylanase
    • Abstract: Publication date: Available online 4 March 2017
      Source:Carbohydrate Research
      Author(s): David Mangan, Claudio Cornaggia, Agnija Liadova, Niall McCormack, Ruth Ivory, Vincent A. McKie, Aaron Ormerod, Barry V. McCleary
      endo-1,4-β-Xylanase (EC 3.2.1.8) is employed across a broad range of industries including animal feed, brewing, baking, biofuels, detergents and pulp (paper). Despite its importance, a rapid, reliable, reproducible, automatable assay for this enzyme that is based on the use of a chemically defined substrate has not been described to date. Reported herein is a new enzyme coupled assay procedure, termed the XylX6 assay, that employs a novel substrate, namely 4,6-O-(3-ketobutylidene)-4-nitrophenyl-β-45-O-glucosyl-xylopentaoside. The development of the substrate and associated assay is discussed here and the relationship between the activity values obtained with the XylX6 assay versus traditional reducing sugar assays and its specificity and reproducibility were thoroughly investigated.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Stereoselective total synthesis of Oxylipin from open chain
           gluco-configured building block
    • Abstract: Publication date: Available online 3 March 2017
      Source:Carbohydrate Research
      Author(s): Santosh Ramdas Borkar, Indrapal Singh Aidhen
      Total synthesis of naturally occurring Oxylipin has been achieved from open chain gluco-configured building block which is readily assembled from inexpensive and commercially available D-(+)-gluconolactone. Grignard reaction and Wittig olefination reactions are key steps for the requisite CC bond formation.
      Graphical abstract image

      PubDate: 2017-03-08T11:04:32Z
       
  • Structural and genetic characterization of the O-antigen of Enterobacter
           cloacae C5529 related to the O-antigen of E. cloacae G3054
    • Abstract: Publication date: Available online 28 February 2017
      Source:Carbohydrate Research
      Author(s): Runhua Han, Andrei V. Perepelov, Yuanyuan Wang, Andrei V. Filatov, Min Wang, Alexander S. Shashkov, Lei Wang, Yuriy A. Knirel
      On mild acid degradation of the lipopolysaccharide of Enterobacter cloacae C5529, the O-polysaccharide chain was cleaved at the linkages of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac). 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 tetrasaccharide repeating unit of the O-polysaccharide was established: →4)-β-Pse5Ac7Ac-(2 → 3)-β-d-Galp-(1 → 6)-β-d-Galf-(1 → 3)-α-d-Galp-(1→ It differs from a structurally related O-polysaccharide of E. cloacae G3045 studied early (Perepelov, A. V.; Wang, M.; Filatov, A. V.; Guo, X.; Shashkov, A. S.; Wang, L.; Knirel, Y. A. Carbohydr. Res. 2015; 407:59–62) in positions of substitution of β-Psep5Ac7Ac (O-4 vs. O-8) and β-Galp (O-3 vs. O-6) and the absence of a side-chain α-Galp residue. The O-antigen gene clusters of E. cloacae C5529 and G3045 are organized identically and include genes with the same putative functions in the O-polysaccharide synthesis. Based on these and serological data, it is suggested to combine E. cloacae C5529 and G3054 in one O-serogroup as two subgroups.
      Graphical abstract image

      PubDate: 2017-03-01T17:07:47Z
       
  • Total syntheses of Prelactone V and Prelactone B
    • Abstract: Publication date: Available online 28 February 2017
      Source:Carbohydrate Research
      Author(s): S. Raghavendra, Krishnaji Tadiparthi, J.S. Yadav
      The total syntheses of natural products Prelactone–V and Prelactone–B have been accomplished by a novel Chiron approach starting from D–glucose. The synthesis involves isopropylidene acetal formation of D-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.
      Graphical abstract image

      PubDate: 2017-03-01T17:07:47Z
       
  • Synthesis and cytotoxicity of oleanolic acid trisaccharide saponins
    • Abstract: Publication date: Available online 28 February 2017
      Source:Carbohydrate Research
      Author(s): Liming Wang, Zengshang Wang, Sheng Su, Ying Xing, Yali Li, Ming Li, Jiangyun Liu, Shilin Yang
      An array of oleanolic acid-type saponins based on β-hederin has been synthesized in a linear or one-pot manner. The cell viability assays indicate that synthetic saponins show antiproliferation activities in three cancer cell lines with IC50 values of 2.4–15.1 μM and hederacolchiside A1 being the most potent. The results demonstrate that the type of terminal monosaccharides and linkage position have apparent effects on cytotoxicities and selectivities of these saponins against cancer cell lines tested. This study is helpful for future development of more potent anticancer leads.
      Graphical abstract image

      PubDate: 2017-03-01T17:07:47Z
       
  • High yield production of Rhizobium NodB chitin deacetylase and its use for
           in vitro synthesis of lipo-chitinoligosaccharide precursors
    • Abstract: Publication date: Available online 27 February 2017
      Source:Carbohydrate Research
      Author(s): Rémi Chambon, Stéphanie Pradeau, Sébastien Fort, Sylvain Cottaz, Sylvie Armand
      Lipo-chitinoligosaccharides (LCOs) are key molecules for the establishment of plant-microorganisms symbiosis. Interactions of leguminous crops with nitrogen-fixing rhizobial bacteria involve Nod factors, while Myc-LCOs improve the association of most plants with arbuscular mycorrhizal fungi. Both Nod factors and Myc-LCOs are composed of a chitinoligosaccharide fatty acylated at the non-reducing end accompanied with various substituting groups. One straightforward way to access LCOs is starting from chitin hydrolysate, an abundant polysaccharide found in crustacean shells, followed by regioselective enzymatic cleavage of an acetyl group from the non-reducing end of chitin tetra- or pentaose, and subsequent chemical introduction of N-acyl group. In the present work, we describe the in vitro synthesis of LCO precursors on preparative scale. To this end, Sinorhizobium meliloti chitin deacetylase NodB was produced in high yield in E. coli as a thioredoxin fusion protein. The recombinant enzyme was expressed in soluble and catalytically active form and used as an efficient biocatalyst for N-deacetylation of chitin tetra- and pentaose.
      Graphical abstract image

      PubDate: 2017-03-01T17:07:47Z
       
  • Direct, microwave-assisted substitution of anomeric nitrate-esters
    • Abstract: Publication date: Available online 24 February 2017
      Source:Carbohydrate Research
      Author(s): D. Jamin Keith, Steven D. Townsend
      A series of carbohydrate 2-azido-1-nitrate-esters, protected at the C-3, C-4, and C-6 positions, were hydrolyzed thermally, under reagent free conditions. This preliminary result was extended to direct exchange of the 1-nitrate-ester modality for alcohol, alkoxy, and azide coupling partners with minimal purification. While direct glycosylation of nitrate esters ultimately proved unsuccessful, we have demonstrated that an anomeric nitrate-ester can be converted directly to a trichloroacetimidate in a short and simple one-pot procedure, bypassing lower-yielding two-step sequences.
      Graphical abstract image

      PubDate: 2017-03-01T17:07:47Z
       
  • Graphical contents list
    • Abstract: Publication date: 22 February–15 March 2017
      Source:Carbohydrate Research, Volumes 440–441


      PubDate: 2017-03-01T17:07:47Z
       
  • Fast purification method of functional LPMOs from Streptomyces ambofaciens
           by affinity adsorption
    • Abstract: Publication date: Available online 21 February 2017
      Source:Carbohydrate Research
      Author(s): Susana V. Valenzuela, Guillem Ferreres, Gerard Margalef, F.I. Javier Pastor
      A simple purification method by affinity adsorption was developed to obtain functional lytic polysaccharide monooxygenases (LPMOs). The system allows the successful purification to homogeneity of the most characterized bacterial LPMO, CBP21 from Serratia marcescens, and two LPMOs from Streptomyces ambofaciens, which have not been previously characterized. The first of these new LPMOs, named SamLPMO10B is a small enzyme (15 kDa) belonging to family 10 of auxiliary activities (AA10), showing activity on β-chitin. The second LPMO, SamLPMO10C (34.7 kDa), is a bimodular enzyme comprised of an AA10 catalytic module and a carbohydrate binding module of family CBM2. SamLPMO10C shows activity on cellulosic substrates, including agricultural fiber paper pulps. The methodology developed simplifies the purification process to a binding-elution protocol with low-grade polysaccharides including Avicel. The strategy can be a cheap, simple and fast solution for the purification of LPMOs for industrial applications, leaving out periplasmic fractionation from recombinant strains therefore, with reduction of time and costs compared to conventional processes. The activity of SamLPMO10C expands the potential of the high valued LPMOs in lignocellulosic biomass valorization, reaffirming their promising role in cellulose deconstruction.
      Graphical abstract image

      PubDate: 2017-02-22T17:21:47Z
       
  • A novel expression system for lytic polysaccharide monooxygenases
    • Abstract: Publication date: Available online 14 February 2017
      Source:Carbohydrate Research
      Author(s): Gaston Courtade, Simone Balzer Le, Gerd Inger Sætrom, Trygve Brautaset, Finn L. Aachmann
      Lytic polysaccharide monooxygenases (LPMOs) are key enzymatic players of lignocellulosic biomass degradation processes. As such, they have been introduced in cellulolytic cocktails for more efficient and less expensive lignocellulose saccharification. The recombinant production of LPMOs in bacteria for scientific investigations using vectors typically based on the T7 and lacUV5 promoters has been hampered by low yields. Reasons for this have been catabolite repression when producing the proteins in defined media with glucose as the sole carbon source, as well as the lack of an inducible expression system that allows controlled production of LPMOs that are correctly processed during translocation to the periplasmic space. A cassette vector design containing the XylS/Pm system was constructed and evaluated, showing that the expression cassette could easily be used for exchanging LPMO coding genes with or without signal sequences. The cassette was shown to reliably produce mature (translocated) LPMOs under controlled conditions that were achieved by using a low dosage (0.1 mM) of the Pm inducer m-toluic acid and a low (16 °C) cultivation temperature after induction. Furthermore, the signal sequences of five bacterial LPMOs were tested, and the signal sequence of LPMO10A from Serratia marcescens was found to give highest levels of recombinant protein production and translocation. The LPMO expression cassette was also evaluated in cultivations using defined media with glucose as the sole carbon source with a product yield of 7–22 mg per L of culture in shaking flasks. The integrity of the recombinant proteins were analyzed using NMR spectroscopy, showing that the system produced correctly processed and folded LPMOs. Finally, high cell-density cultivations of the recombinant strains were carried out, demonstrating stable protein production levels at similar relative yields (42–1298 mg per L of culture; 3.8–11.6 mg per OD600nm unit) as in shaking flasks, and showing the scale-up potential of the system.
      Graphical abstract image

      PubDate: 2017-02-15T17:15:12Z
       
  • Hydrothermal conversion of N-acetyl-d-glucosamine to
           5-hydroxymethylfurfural using ionic liquid as a recycled catalyst in a
           water-dimethyl sulfoxide mixture
    • Abstract: Publication date: Available online 11 February 2017
      Source:Carbohydrate Research
      Author(s): Hongjun Zang, Songbai Yu, Pengfei Yu, Hongying Ding, Yannan Du, Yuchan Yang, Yiwen Zhang
      Here, N-acetyl-d-glucosamine (GlcNAc), the monomer composing the second most abundant biopolymer, chitin, was efficiently converted into 5-hydroxymethylfurfural (5-HMF) using ionic liquid (IL) catalysts in a water/dimethyl sulfoxide (DMSO) mixture solvent. Various reaction parameters, including reaction temperature and time, DMSO/water mass ratios and catalyst dosage were optimized. A series of ILs with different structures were analyzed to explore their impact on GlcNAc conversion. The substrate scope was expanded from GlcNAc to d-glucosamine, chitin, chitosan and monosaccharides, although 5-HMF yields obtained from polymers and other monosaccharides were generally lower than those from GlcNAc. Moreover, the IL N-methylimidazolium hydrogen sulfate ([Hmim][HSO4]) exhibited the best catalyst performance (64.6% yield) when GlcNAc was dehydrated in a DMSO/water mixture at 180 °C for 6 h without the addition of extra catalysts. To summarize, these results could provide knowledge essential to the production of valuable chemicals that are derived from renewable marine resources and benefit biofuel-related applications.
      Graphical abstract image

      PubDate: 2017-02-15T17:15:12Z
       
  • Synthesis of lacto-N-tetraose
    • Abstract: Publication date: Available online 11 February 2017
      Source:Carbohydrate Research
      Author(s): Kelly M. Craft, Steven D. Townsend
      Human milk oligosaccharides (HMOs) are the third largest macromolecular component of breast milk and offer infants numerous health benefits, most of which stem from the development of a healthy microbiome. Characterization, quantification, and chemical derivatization of HMOs remains a frontier issue in glycobiology due to the challenge of isolating appreciable quantities of homogenous HMOs from breast milk. Herein, we report the synthesis of the human milk tetrasaccharide lacto-N-tetraose (LNT). LNT is ubiquitous in human breast milk as it is a core structure common to longer-chain HMOs and many glycolipids.
      Graphical abstract image

      PubDate: 2017-02-15T17:15:12Z
       
  • Graphical contents list
    • Abstract: Publication date: 1 February 2017
      Source:Carbohydrate Research, Volume 439


      PubDate: 2017-02-03T03:35:18Z
       
  • Structural analysis of rebaudioside A derivatives obtained by
           Lactobacillus reuteri 180 glucansucrase-catalyzed trans-α-glucosylation
    • Abstract: Publication date: Available online 31 January 2017
      Source:Carbohydrate Research
      Author(s): Gerrit J. Gerwig, Evelien M. te Poele, Lubbert Dijkhuizen, Johannis P. Kamerling
      The wild-type Gtf180-ΔN glucansucrase enzyme from Lactobacillus reuteri 180 was found to catalyze the α-glucosylation of the steviol glycoside rebaudioside A, using sucrose as glucosyl donor in a transglucosylation process. Structural analysis of the formed products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that rebaudioside A is specifically α-D-glucosylated at the steviol C-19 β-D-glucosyl moiety (55% conversion). The main product is a mono-(α1 → 6)-glucosylated derivative (RebA-G1). A series of minor products, up to the incorporation of eight glucose residues, comprise elongations of RebA-G1 with mainly alternating (α1 → 3)- and (α1 → 6)-linked glucopyranose residues. These studies were carried out in the context of a program directed to the improvement of the taste of steviol glycosides via enzymatic modification of their naturally occurring carbohydrate moieties.
      Graphical abstract image

      PubDate: 2017-02-03T03:35:18Z
       
  • Structure of the LPS O-chain from Fusobacterium nucleatum strain 10953,
           containing sialic acid
    • Abstract: Publication date: Available online 28 January 2017
      Source:Carbohydrate Research
      Author(s): Evgeny Vinogradov, Frank St. Michael, Kiyonobu Homma, Ashu Sharma, Andrew D. Cox
      Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about virulence factors of this organism and thus we have initiated studies to examine the bacterial surface glycochemistry. Consistent with a recent paper suggesting that F. nucleatum strain 10593 can synthesize sialic acid, a staining technique identified sialic acid on the bacterial surface. We isolated lipopolysaccharide from this F. nucleatum strain and performed structural analysis on the O-antigen. Our studies identified a trisaccharide repeating unit of the O-antigen with the following structure: -[→4)-α-Neup5Ac-(2 → 4)-β-d-Galp-(1 → 3)-α-d-FucpNAc4NAc-(1-]- where Ac indicates 4-N-acetylation of ∼30% FucNAc4N residues. The presence of sialic acid as a constituent of the O-antigen is consistent with recent data identifying de novo sialic acid synthesis in this strain.
      Graphical abstract image

      PubDate: 2017-02-03T03:35:18Z
       
  • Synthesis of an allergy inducing tetrasaccharide “4P-X”
    • Abstract: Publication date: 1 February 2017
      Source:Carbohydrate Research, Volume 439
      Author(s): Takashi Moriya, Naoki Nagahata, Rei Odaka, Hirohide Nakamura, Jun Yoshikawa, Katsumi Kurashima, Tadao Saito
      4P-X (β-D-galactopyranosyl-(1 → 4)-β-D-galactopyranosyl-(1 → 6)-[β-D-galactopyranosyl-(1 → 4)]-β-D-glucopyranose) is included in galacto-oligosaccharides (GOSs) produced by β-galactosidase derived from Bacillus circulans. 4P-X has been known to induce particularly strong allergies. High purity 4P-X is essential for use as a standard to quantify the amount of 4P-X in GOSs; however, the isolation of high purity 4P-X has never been reported. In this study, we achieved the synthesis of 4P-X by a combination of organic and enzymatic chemical syntheses in a short time. This is the first report of isolated, high purity 4P-X.
      Graphical abstract image

      PubDate: 2017-01-21T09:02:46Z
       
  • 4-hydroxybenzaldehyde-chitooligomers suppresses H2O2-induced oxidative
           damage in microglia BV-2 cells
    • Abstract: Publication date: Available online 16 January 2017
      Source:Carbohydrate Research
      Author(s): Sea-Hun Oh, Bomi Ryu, Dai-Hung Ngo, Won-Suk Kim, Dong Gyu Kim, Se-Kwon Kim
      Positive charges of chitooligomer (COS) enable COS to interact with negatively charged anionic groups on the cell surface resulting in an improvement in the biological activity of COS and its derivatives. In this study, 4-hydroxybenzaldehyde-COS (HB-COS) was synthesized and investigated for its abilities against H2O2-induced oxidative stress in microglia BV-2 cells. Under oxidative stress, HB-COS significantly attenuated reactive oxygen species (ROS) generation and DNA oxidation, and upregulated the protein levels of antioxidative enzymes. HB-COS is therefore proposed as a potential protective agent against neuronal damage.
      Graphical abstract image

      PubDate: 2017-01-21T09:02:46Z
       
  • C-5a-substituted validamine type glycosidase inhibitors
    • Abstract: Publication date: Available online 13 January 2017
      Source:Carbohydrate Research
      Author(s): Michael Schalli, Andreas Wolfsgruber, Andres Gonzalez Santana, Christina Tysoe, Roland Fischer, Arnold E. Stütz, Martin Thonhofer, Stephen G. Withers
      A series of N-alkyl derivatives of the D-galactosidase inhibitor 1,4-di-epi-validamine featuring lipophilic substituents at position C-5a was prepared and screened for their glycosidase inhibitory properties. Products turned out selective for β-galactosidases as well as β-glucosidases.
      Graphical abstract image

      PubDate: 2017-01-21T09:02:46Z
       
  • Isomelezitose formation by glucansucrases
    • Abstract: Publication date: Available online 11 January 2017
      Source:Carbohydrate Research
      Author(s): Gregory L. Côté, Christopher D. Skory
      Several glucansucrases were surveyed for their ability to produce isomelezitose, a trisaccharide with the structure α-D-glucopyranosyl (1 → 6) β-D-fructofuranosyl (2 ↔ 1) α-D-glucopyranoside. Nearly all strains tested, with one exception, produced at least trace levels of isomelezitose. Yields were low but significant, ranging from less than 1% to approximately 5% based on sucrose. This trisaccharide may arise in either of two ways: glucopyranosyl transfer to the 6Fru-OH position of sucrose, or to the anomeric OH position of isomaltulose. This study indicates that isomelezitose formation may be a general phenomenon of many glucansucrase reactions.
      Graphical abstract image

      PubDate: 2017-01-13T08:43:52Z
       
  • Large scale synthesis and regioselective protection schemes of ethyl
           2-azido-2-deoxy-1-thio-α-D-cellobioside for preparation of heparin
           thiodisaccharide building blocks
    • Abstract: Publication date: Available online 11 January 2017
      Source:Carbohydrate Research
      Author(s): Kevin Sheerin, Lorenzo Guazzelli, Stefan Oscarson
      Crystalline acetylated ethyl 2-azido-2-deoxy-1-thio-α-d-cellobioside has been prepared on a multigram scale from cellobiose in an overall yield of 23% with no chromatography required and converted after deacetylation into the 4′,6′-O-benzylidene and 4′,6′-O-benzylidene-6-O-TBDMS protected derivatives. Applying a number of regioselective benzylation methods on these gave access to a variety of regioselectively protected derivatives, both mono-ols (2′- and 3-OH), diols (2′,6-, 2′,3-, and 3,6-di-OH), and triols (2′,3,6- and 2′,3′,3-tri-OH). A number of these derivatives were further processed by benzoylation followed by removal or opening of the benzylidene acetal and selective oxidation of the exposed primary alcohol to give heparin building block intermediates comprising a range of possible sulfation patterns.
      Graphical abstract image

      PubDate: 2017-01-13T08:43:52Z
       
  • The structure of the LPS O-chain of Fusobacterium nucleatum strain 25586
           containing two novel monosaccharides, 2-acetamido-2,6-dideoxy-l-altrose
           and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid
    • Abstract: Publication date: Available online 9 January 2017
      Source:Carbohydrate Research
      Author(s): Evgeny Vinogradov, Frank St. Michael, Andrew D. Cox
      Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about the virulence factors of this organism, and thus we have initiated studies to examine the bacterium's surface glycochemistry. We isolated lipopolysaccharide (LPS) from F. nucleatum strain 25586 and purified and performed structural analysis on the O-antigen polysaccharide. The polysaccharide contained two novel sugars, 2-acetamido-2,6-dideoxy-l-altrose (l-6dAltNAc) and a 5-acetimidoylamino-3,5,9-trideoxy-gluco-non-2-ulosonic acid (Non5Am), which was tentatively assigned the l -glycero- l -gluco configuration. The polysaccharide was found to have a trisaccharide repeating unit, which is phosphorylated with phosphocholine (PCho), and the following structure was established: -[-4-β-Nonp5Am-4-α-l-6dAltpNAc3PCho-3-β-d-QuipNAc-]- We propose the trivial name ‘fusaminic acid’ for the novel nonulosonic acid. It is the first occurrence of a 9-deoxynonulosonic acid with a hydroxyl group at C-7, which is occupied by an amino group in all monosaccharides of this class described so far.
      Graphical abstract image

      PubDate: 2017-01-13T08:43:52Z
       
  • Discrimination between naphthacene and triphenylene using cellulose
           tris(4-methylbenzoate) and cellulose tribenzoate: A computational study
    • Abstract: Publication date: Available online 7 January 2017
      Source:Carbohydrate Research
      Author(s): Yusuke Murakami, Tohru Shibata, Kazuyoshi Ueda
      The mechanisms of naphthacene and triphenylene discrimination using commercially available cellulose tris(4-methylbenzoate) (CMB) and cellulose tribenzoate (CB) chiral stationary phases were investigated using molecular mechanics calculations. Naphthacene and triphenylene could be separated by liquid chromatography on CMB and CB, with triphenylene being eluted earlier than naphthacene on both phases. However, the corresponding separation factor is much larger for CMB than for CB. The docking of these polycyclic aromatic hydrocarbons to the above polymers suggested that the most important sites of CMB and CB for interacting with these hydrocarbons are located at equivalent positions, featuring a space surrounded by main chain glucose units and benzoyl side chains. The difference of hydrocarbon stabilization energies with CMB and CB agreed well with the observed chromatographic separation factors.
      Graphical abstract image

      PubDate: 2017-01-13T08:43:52Z
       
  • Influence of aglycone structures on N-glycan processing reactions in the
           endoplasmic reticulum
    • Abstract: Publication date: 1 February 2017
      Source:Carbohydrate Research, Volume 439
      Author(s): Kiichiro Totani, Kenta Yamaya, Makoto Hirano, Yukishige Ito
      Glycoprotein N-linked oligosaccharides in the endoplasmic reticulum function as tags to regulate glycoprotein folding, sorting, secretion and degradation. Since the N-glycan structure of a glycoprotein should reflect the folding state, N-glycan processing may be affected by the aglycone state. In this study, we examined the influence of aglycone structures on N-glycan processing using synthetic substrates. We prepared (Glc1)Man9GlcNAc2 linked to hydrophobic BODIPY-dye with a systematic series of different linker lengths. With these compounds, glucose transfer, glucose trimming and mannose trimming reactions of an endoplasmic reticulum fraction were examined. The results showed that substrates with shorter linkers between the N-glycan and hydrophobic patch had higher activities for both the glucose transfer and the mannose trimming reactions. In contrast, the glucose trimming reaction showed lower activity when substrates had shorter linkers. Thus, the reactivity for N-linked oligosaccharide processing of glycoproteins in the endoplasmic reticulum might be tunable by the aglycone structure, e.g., protein portion of glycoproteins.
      Graphical abstract image

      PubDate: 2017-01-06T13:50:17Z
       
  • Structure of O-specific polysaccharide of Oligotropha carboxidovorans OM5
           - A wastewater bacterium
    • Abstract: Publication date: Available online 3 January 2017
      Source:Carbohydrate Research
      Author(s): Iwona Komaniecka, Adam Choma, Katarzyna Zamlynska, Anna Sroka-Bartnicka, Pawel Sowinski
      Oligotropha carboxidovorans strain OM5 (previously known as Pseudomonas carboxydovorans OM5) is a rod-shaped Gram-negative bacterium isolated from wastewater. This bacterium is able to live in aerobic and, facultatively, in autotrophic conditions. For autotrophic growth, the bacteria can utilize carbon monoxide or hydrogen as a source of energy. The O-specific polysaccharide isolated from O. carboxidovorans OM5 lipopolysaccharide was structurally characterized using chemical analyses, 1D and 2D NMR spectroscopy, and MALDI-TOF mass spectrometry techniques. The polysaccharide was found to be a homopolymer built up of 3-O-methyl-α-d-mannose residues linked by (1 → 2)-glycosidic bonds. The degree of polymerization of high-molecular-weight polysaccharide was estimated at approximately 35–40 units. The structure of the homopolymer is depicted below: [→2)-3-OMe-α-d-Manp-(1→]∼35-40
      Graphical abstract image

      PubDate: 2017-01-06T13:50:17Z
       
  • Graphical contents list
    • Abstract: Publication date: 13 January 2017
      Source:Carbohydrate Research, Volume 438


      PubDate: 2016-12-27T06:46:27Z
       
  • New investigators in glycoscience
    • Abstract: Publication date: 13 January 2017
      Source:Carbohydrate Research, Volume 438
      Author(s): Rob Field


      PubDate: 2016-12-27T06:46:27Z
       
  • Removal of some common glycosylation by-products during reaction work-up
    • Abstract: Publication date: Available online 24 December 2016
      Source:Carbohydrate Research
      Author(s): Mads Heuckendorff, Henrik H. Jensen
      With the aim of improving the general glycosylation protocol to facilitate easy product isolation it was shown that amide by-products from glycosylation with trichloroacetimidate and N-phenyl trifluoroacetimidate donors could be removed during reaction work-up by washing with a basic aqueous solution. Excess glycosyl acceptor or lactol originating from glycosyl donor hydrolysis could equally be removed from the reaction mixture by derivatization with a basic tag and washing with an acidic solution during reaction work-up.
      Graphical abstract image

      PubDate: 2016-12-27T06:46:27Z
       
  • Structure of the O-specific polysaccharide from the lipopolysaccharide of
           Aeromonas hydrophila strain K691 containing
           4-acetamido-4,6-dideoxy-D-glucose
    • Abstract: Publication date: Available online 23 December 2016
      Source:Carbohydrate Research
      Author(s): Katarzyna Pakiet, Anna Turska-Szewczuk, Magdalena A. Karas, Agnieszka Pekala, Hubert Pietras
      The O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Aeromonas hydrophila strain K691 and studied by chemical methods and 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, NOESY, 1H-detected heteronuclear 1H,13C HSQC, and HMBC experiments. It was found that the O-specific polysaccharide was built up of pentasaccharide repeating units composed of β-GlcpNAc, 2-O-acetylated α-Rhap, and β-Quip4NAc residues. The following structure of the OPS was established: →3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→2)-β-d-Qui4NAc-(1→
      Graphical abstract image

      PubDate: 2016-12-27T06:46:27Z
       
  • Evaluation of carbohydrate-cysteamine thiazolidines as pro-drugs for the
           treatment of cystinosis
    • Abstract: Publication date: Available online 18 December 2016
      Source:Carbohydrate Research
      Author(s): Yasaman Ramazani, Elena N. Levtchenko, Lambertus Van Den Heuvel, Ann Van Schepdael, Prasanta Paul, Ekaterina A. Ivanova, Anna Pastore, Trina M. Hartman, Neil P.J. Price
      Cystinosis is a genetic disorder caused by malfunction of cystinosin and is characterized by accumulation of cystine. Cysteamine, the medication used in cystinosis, causes halitosis resulting in poor patient compliance. Halitosis is mainly caused by the formation of dimethylsulfide as the final product in the cysteamine metabolism pathway. We have synthesized carbohydrate-cysteamine thiazolidines, and hypothesized that the hydrolytic breakdown of cysteamine-thiazolidines can result in free cysteamine being released in target organs. To examine our hypothesis, we tested these analogs in vitro in patient-derived fibroblasts. Cystinotic fibroblasts were treated with different concentrations of arabinose-cysteamine, glucose-cysteamine and maltose-cysteamine. We demonstrated that the analogs break down into cysteamine extracellularly and might therefore not be fully taken up by the cells under the form of the pro-drug. Potential modifications of the analogs that enable their intracellular rather than extracellular breakdown, is necessary to pursue the potential of these analogs as pro-drugs.
      Graphical abstract image

      PubDate: 2016-12-20T09:41:49Z
       
  • Photoswitchable carbohydrate-based fluorosurfactants as tuneable ice
           recrystallization inhibitors
    • Abstract: Publication date: Available online 14 December 2016
      Source:Carbohydrate Research
      Author(s): Madeleine K. Adam, Yingxue Hu, Jessica S. Poisson, Matthew J. Pottage, Robert N. Ben, Brendan L. Wilkinson
      Cryopreservation is an important biomedical technique employed for the storage and preservation of biological tissues and cells. The limited effectiveness and significant toxicity of conventionally-used cryoprotectants, such as DMSO, have prompted efforts toward the rational design of less toxic alternatives, including carbohydrate surfactants. In this paper, we report the modular synthesis and ice recrystallization inhibition (IRI) activity of a library of variably substituted, carbohydrate-based fluorosurfactants. Carbohydrate-based fluorosurfactants possessed a variable mono- or disaccharide head group appended to a hydrophobic fluoroalkyl-substituted azobenzene tail group. Light-addressable fluorosurfactants displayed weak-to-moderate IRI activity that could be tuned through selection of carbohydrate head group, position of the trifluoroalkyl group on the azobenzene ring, and isomeric state of the azobenzene tail fragment.
      Graphical abstract image

      PubDate: 2016-12-20T09:41:49Z
       
  • Synthesis and NMR analysis of model compounds related to fucosylated
           chondroitin sulfates: GalNAc and Fuc(1 → 6)GalNAc derivatives
    • Abstract: Publication date: 13 January 2017
      Source:Carbohydrate Research, Volume 438
      Author(s): Dmitry Z. Vinnitskiy, Nadezhda E. Ustyuzhanina, Andrey S. Dmitrenok, Alexander S. Shashkov, Nikolay E. Nifantiev
      Unsubstituted and 6-O-α-L-fucosylated propyl 2-acetamido-2-deoxy-β-D-galactopyranosides and their selectively O-sulfated (both in GalNAc and Fuc units) derivatives were synthesized as model compounds representing the fragments of fucosylated chondroitin sulfates (FCS) from sea cucumbers. Per-O-acetylated 2-deoxy-2-N-phthalimido-D-glucopyranose was used as a key precursor for the preparation of all 2-acetamido-2-deoxy-D-galactopyranoside containing products. Attempts at 6-O-glycosylation of propyl 3-O-benzoyl-2-deoxy-2-N-phthalimido-D-galactoside by 2-O-benzyl-3,4-di-O-chloracetyl-L-fucosyl trichloracetimidate in the presence of TMSOTf gave a 1:1 mixture of the corresponding α- and β-isomeric disaccharides, while the use of structurally related fucosyl bromide donor with promotion by Bu4NBr led to the formation of desired α-isomeric disaccharide exclusively. Selective removal of orthogonal O-protections permitted subsequent O-sulfation both at the GalNAc and Fuc units. Further removal of blocking groups yielded the target products which were systematically studied by 1H and 13C NMR spectroscopy in order to determine the spectral effects of O-sulfation and α-L-fucosylation needed for the development of computer assisted structural analysis of natural FCS.
      Graphical abstract image

      PubDate: 2016-12-13T09:32:46Z
       
  • Investigating the relationship between temperature, conformation and
           calcium binding in heparin model oligosaccharides
    • Abstract: Publication date: Available online 9 December 2016
      Source:Carbohydrate Research
      Author(s): Ashley Hughes, Maria Meneghetti, Teng-Yi Huang, Shang-Cheng Huang, Stefano Elli, Marco Guerrini, Timothy Rudd, Marcelo Lima, Edwin Yates
      Glycosaminoglycans such as heparan sulfate (HS) are major components of the cell surface and extracellular matrix (ECM) of all multicellular animals, connecting cells to each other as well as to their environment. The ECM must, therefore, both sense and accommodate changes to external conditions. Heparin, a model compound for HS, responds to increased temperatures, involving changes in the populations of conformational states with implications for the binding of HS to proteins, cations and, potentially, for its activity. A fully 13C and 15N labelled model octasasccharide; D-GlcNS6S α(1-4) L-IdoA2S [α(1-4) D-GlcNS6S α(1-4) L-IdoA2S]2 α(1-4) D-GlcNS6S α(1-4) L-IdoA1,6an, was studied by 1H, 13C and 15N NMR, revealing complex changes in chemical shifts and conformation, over temperatures (280–305 K), comfortably within the range relevant to terrestrial biology. These complex conformational changes indicated an interaction between the carboxylate group of L-iduronate and D-glucosamine residues that was susceptible to temperature changes in this range, while the well-documented hydrogen bond between the N-sulfamido group of glucosamine and the hydroxyl group at position-3 of iduronate remained intact. Unexpectedly, despite the presence of similar thermally-induced conformational changes in a heparin octasaccharide fraction in the sodium ion form, its subsequent binding to calcium ions and their resulting conformation was stringently maintained, as judged by comparisons of 1H NMR chemical shifts.
      Graphical abstract image

      PubDate: 2016-12-13T09:32:46Z
       
  • Synthesis of aza-crown analogues and macrocyclic bis-lactams with sucrose
           scaffold
    • Abstract: Publication date: Available online 5 December 2016
      Source:Carbohydrate Research
      Author(s): Michał Kowalski, Sławomir Jarosz
      2,3,3′,4,4′-Penta-O-benzylsucrose was converted into the corresponding diaminoalcohol which was used as a key building block in the synthesis of the analogues of aza-crown ethers and bis-lactams.
      Graphical abstract image

      PubDate: 2016-12-06T09:25:11Z
       
  • Fluorescent mannosides serve as acceptor substrates for
           glycosyltransferase and sugar-1-phosphate transferase activities in
           Euglena gracilis membranes
    • Abstract: Publication date: Available online 30 November 2016
      Source:Carbohydrate Research
      Author(s): Irina M. Ivanova, Sergey A. Nepogodiev, Gerhard Saalbach, Ellis C. O'Neill, Michael D. Urbaniak, Michael A.J. Ferguson, Sudagar S. Gurcha, Gurdyal S. Besra, Robert A. Field
      Synthetic hexynyl α-D-mannopyranoside and its α-1,6-linked disaccharide counterpart were fluorescently labelled through CuAAC click chemistry with 3-azido-7-hydroxycoumarin. The resulting triazolyl-coumarin adducts, which were amenable to analysis by TLC, HPLC and mass spectrometry, proved to be acceptor substrates for α-1,6-ManT activities in mycobacterial membranes, as well as α- and β-GalT activities in trypanosomal membranes, benchmarking the potential of the fluorescent acceptor approach against earlier radiochemical assays. Following on to explore the glycobiology of the benign protozoan alga Euglena gracilis, α-1,3- and α-1,2-ManT activities were detected in membrane preparations, along with GlcT, Glc-P-T and GlcNAc-P-T activities. These studies serve to demonstrate the potential of readily accessible fluorescent glycans as substrates for exploring carbohydrate active enzymes.
      Graphical abstract image

      PubDate: 2016-12-06T09:25:11Z
       
  • One-pot Mukaiyama type carbon-Ferrier rearrangement of glycals:
           Application in the syntheses of chromanone 3-C-glycosides
    • Abstract: Publication date: Available online 30 November 2016
      Source:Carbohydrate Research
      Author(s): Ashutosh K. Dash, Tatina Madhubabu, Syed Khalid Yousuf, Sushil Raina, Debaraj Mukherjee
      One-pot carbon-Ferrier rearrangement of glycals with unactivated aryl methyl ketones has been developed under mild Silyl triflate catalysis. Keto methyl group of various aryl methyl ketones without being converted into silyl enol ether could directly attack anomeric position of glycals to form keto functionalized C-glycosides in moderate to good yields with high α-selectivity. The versatility of this method has been extended to the synthesis of a small library of chromanone 3-C-glycosides.
      Graphical abstract image

      PubDate: 2016-12-06T09:25:11Z
       
  • Carbohydrate-based aza-macrocycles by Richman-Atkins cyclization of
           glucopyranose precursors
    • Abstract: Publication date: Available online 29 November 2016
      Source:Carbohydrate Research
      Author(s): Andreas Rathjens, Joachim Thiem
      2, 3-Di-ω-halo- as well as 2, 3-di-ω-toluenesulfonamide-alkylated glucopyranoside derivatives were prepared. Their condensation with α,ω-bis-toluenesulfonamide components under varying Richman-Atkins conditions with alkali carbonate in DMF led to carbohydrate-linked aza-macrocycles displaying 14-, 17-, 18-, 21-, 24-, and 25-membered ring structures. Isomeric aza-macrocylic coronands of 20- as well as 30-membered ring size containing two saccharides could be obtained employing Richman-Atkins condensations of two functionalized sugar building units.
      Graphical abstract image

      PubDate: 2016-11-30T04:30:11Z
       
 
 
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