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  Subjects -> CHEMISTRY (Total: 842 journals)
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CHEMISTRY (594 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 8)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 33)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 23)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 230)
ACS Photonics     Full-text available via subscription   (Followers: 11)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
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: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 50)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 14)
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: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 19)
Advances in Nanoparticles     Open Access   (Followers: 14)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
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: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 26)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 14)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 159)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 211)
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: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
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: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 28)
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: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 287)
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: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 110)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 94)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 66)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 70)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 174)
Chemical Science     Open Access   (Followers: 21)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 145)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 18)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Full-text available via subscription   (Followers: 247)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
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: 9)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
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: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
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: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 2)
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: 11)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 58)
Dalton Transactions     Full-text available via subscription   (Followers: 21)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 9)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)
Environmental Science : Nano     Partially Free   (Followers: 1)

        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  [3043 journals]
  • Tunable stereoselectivity in the synthesis of α- and β-aryl glycosides
           using 1,2-α-anhydrosugars as glycosyl donors
    • Abstract: Publication date: 8 September 2017
      Source:Carbohydrate Research, Volume 449
      Author(s): Devaraj Somasundaram, Kalpattu K. Balasubramanian, Shanmugasundaram Bhagavathy
      The stereochemical course of O-glycosidation of 1,2-α -d-anhydrosugars (glycal epoxides) with phenols can be tuned by varying the metal ion of the base. While the reaction of 1,2-α -d-anhydrosugars with phenols mediated by trimethylaluminium leads exclusively to 1,2-cis-α-O-aryl glycosides, similar reaction mediated by caesium carbonate gives exclusively 1,2-trans-β-O-aryl glycosides. In contrast, reaction with phenoxides generated from Grignard reagent and calcium salts affords mixture of the anomers.
      Graphical abstract image

      PubDate: 2017-08-02T11:27:21Z
       
  • Physakengoses K-Q, seven new sucrose esters from Physalis alkekengi var.
           franchetii
    • Abstract: Publication date: Available online 28 July 2017
      Source:Carbohydrate Research
      Author(s): Chuan-Yang Zhang, Jian-Guang Luo, Rui-Huan Liu, Ru Lin, Ming-Hua Yang, Ling-Yi Kong
      Seven sucrose esters, physakengoses K-Q (1–7) were isolated from the aerial parts of Physalis alkekengi var. franchetii. Their structures were elucidated on the basis of extensive spectroscopic analyses and chemical methods. These new compounds were tested for their antimicrobial abilities against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. Among the isolated sucrose esters, compounds 1–5 showed potent antibacterial activity with MIC values ranging from 2.16 to 12.76 μg/mL.
      Graphical abstract image

      PubDate: 2017-08-02T11:27:21Z
       
  • Anti-inflammatory effect of sugar-amino acid Maillard reaction products on
           intestinal inflammation model in vitro and in vivo
    • Abstract: Publication date: 8 September 2017
      Source:Carbohydrate Research, Volume 449
      Author(s): Jun-Gu Oh, Su-Hyun Chun, Da Hyun Kim, Jin Hye Kim, Hye Soo Shin, Yong Soo Cho, Yong Ki Kim, Hee-don Choi, Kwang-Won Lee
      The Maillard reaction is a nonenzymatic reaction between an amino acid and a reducing sugar that usually occurs upon heating. This reaction occurs routinely in cooking, generates numerous products, which are collectively referred to as Maillard reaction products (MRPs) contributing to aroma and color features. Advanced glycation end-products (AGEs) transformed from MRPs are participated in many types of inflammation reaction. In this study, various sugar-amino acid MRPs were prepared from three different amino acids (lysine, arginine, and glycine) and sugars (glucose, fructose, and galactose) for 1 h with heating at 121 °C. Treatment of lipopolysaccharide-stimulated RAW264.7 macrophages with the MRPs decreased nitric oxide (NO) expression compared to control without MRPs treatment. MRPs derived from lysine and galactose (Lys-Gal MRPs) significantly inhibited NO expression. The retentate fraction of Lys-Gal MRPs with cut-off of molecular weight of 3–10 kDa (LGCM) suppressed NO expression more effectively than did Lys-Gal MRPs. The anti-inflammatory effect of LGCM was evaluated using a co-culture system consisting of Caco-2 (apical side) and RAW264.7 or THP-1 (basolateral side) cells to investigate the gut inflammation reaction by stimulated macrophage cells. In this system, LGCM prevented a decreased transepithelial electrical resistance, and decreased both tumor necrosis factor-α production in macrophages and interleukin (IL)-8 and IL-1β mRNA expression in Caco-2 cells. In co-culture and in vivo dextran sulfate sodium (DSS)-induced colitis model study, we also observed the anti-inflammatory activity of LGCM.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • Graphical contents list
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448


      PubDate: 2017-07-23T08:05:19Z
       
  • Glycerol mycolates from synthetic mycolic acids
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Omar T. Ali, Mohaned M. Sahb, Juma'a R. Al Dulayymi, Mark S. Baird
      R- and S-Glycerol mycolates derived from single synthetic α-, keto- and methoxy-mycolic acids are described.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • Exhaustive rotamer search of the 4C1 conformation of α- and
           β-d-galactopyranose
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Enrique A. Del Vigo, Carla Marino, Carlos A. Stortz
      An exhaustive search approach was used to establish all possible rotamers of α- and β-d-galactopyranose using DFT at the B3LYP/6-311+G** and M06-2X/6-311+G** levels, both in vacuum calculations, and including two variants of continuum solvent models as PCM and SMD to simulate water solutions. Free energies were also calculated. MM3 was used as the starting point for calculations, using a dielectric constant of 1.5 for vacuum modeling, and 80 for water solution modeling. For the vacuum calculations, out of the theoretically possible 729 rotamers, only about a hundred rendered stable minima, highly stabilized by hydrogen bonding and scattered in a ca. 14 kcal/mol span. The rotamer with a clockwise arrangement of hydrogen bonds was the most stable for the α-anomer, whereas that with a counterclockwise arrangement was the most stable for the β-anomer. Free energy calculations, and especially solvent modeling, tend to flatten the potential energy surface. With PCM, the total range of energies was reduced to 9–10 kcal/mol (α-anomer) or 7–8 kcal/mol (β-anomer). These figures fall to 4.5–6 kcal/mol using SMD. At the same time, the total number of possible rotamers increases dramatically to about 300 with PCM, and to 400 with SMD. Both models show a divergent behavior: PCM tends to underestimate the effect of solvent, thus rendering as the most stable many common rotamers with vacuum calculations, and giving underestimations of populations of β-anomers and gt rotamers in the equilibrium. On the other hand, SMD gives a better estimation of the solvent effect, yielding correct populations of gt rotamers, but more β-anomers than expected by the experimental values. The best agreement is observed when the functional M06-2X is combined with SMD. Both DFT models show minimal geometrical differences between the optimized conformers.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • Fungal secretomics to probe the biological functions of lytic
           polysaccharide monooxygenases
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Jean-Guy Berrin, Marie-Noëlle Rosso, Maher Abou Hachem
      Enzymatic degradation of plant biomass is of growing interest for the development of a sustainable bio-based industry. Filamentous fungi, which degrade complex and recalcitrant plant polymers, are proficient secretors of enzymes acting on the lignocellulose composite of plant cell walls in addition to starch, the main carbon storage reservoir. In this review, we focus on the identification of lytic polysaccharide monooxygenases (LPMOs) and their redox partners in fungal secretomes to highlight the biological functions of these remarkable enzyme systems and we discuss future trends related to LPMO-potentiated bioconversion.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • A bioinformatics analysis of 3400 lytic polysaccharide oxidases from
           family AA9
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Nicolas Lenfant, Matthieu Hainaut, Nicolas Terrapon, Elodie Drula, Vincent Lombard, Bernard Henrissat
      Lytic polysaccharide monooxygenases of family AA9 catalyze the oxidative cleavage of glycosidic bonds in cellulose and related polysaccharides. The N-terminal half of AA9 LPMOs displays a huge sequence variability that is in contradiction with the substrate simplicity so far observed for these enzymes. To understand the cause of the high multigenicity that prevails in the family, we have performed a clustering analysis of the N-terminal region of 3400 sequences of family AA9 LPMOs, and have evaluated the coincidence of the clusters with distal visible features that may accompany functional differences. A method based on local pairwise alignments was devised to avoid the pitfalls of a global multiple alignment. Our analysis allowed the definition of 64 clusters, which successfully segregated several visible features associated to LPMO family AA9, such as the presence of carbohydrate-binding modules, of modules of unknown function and of the conspicuous H → R substitution at the first residue of the histidine brace that holds the catalytic copper. Our analysis shows that the hypervariability of the N-terminal half of the AA9 sequences is not driven by random evolution as sequence similarity does not follow solely taxonomy. The results suggest that some clusters are perhaps able to target chitin instead of cellulose, and that preference for C1 or C4 oxidation (or lack thereof), does not appear to constitute a strong evolutionary constraint. On an evolutionary standpoint, there seems to be little constraints that apply to the N-terminal half of the sequences other than the conservation of the histidine brace. The weak evolutionary constraints that apply to the N-terminal half of AA9 LPMOs explain both their hypervariability and multigenicity.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • Recombinant expression of Thermobifida fusca E7 LPMO in Pichia pastoris
           and Escherichia coli and their functional characterization
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Kelly B. Rodrigues, Jéssica K.A. Macêdo, Tallyta Teixeira, Jéssica S. Barros, Ana C.B. Araújo, Fernanda P. Santos, Betânia F. Quirino, Bruno S.A.F. Brasil, Thaís F.C. Salum, Patrícia V. Abdelnur, Léia C.L. Fávaro
      The discovery of lytic polysaccharides monooxygenases copper dependent (LPMOs) revolutionized the classical concept that the cleavage of cellulose is a hydrolytic process in recent years. These enzymes carry out oxidative cleavage of cellulose (and other polysaccharides), acting synergistically with cellulases and other hydrolases. In fact, LPMOs have the potential for increasing the efficiency of the lignocellulosic biomass conversion in biofuels and high value chemicals. Among a small number of microbial LPMOs that have been characterized, some LPMOs were expressed and characterized biochemically from the bacteria Thermobifida fusca, using the host Escherichia coli. In this work, the E7 LPMO protein of T. fusca was expressed both in E. coli (native DNA sequence) and Pichia pastoris (codon-optimized DNA sequence), for further analysis of oxidative cleavage, with PASC (phosphoric acid swollen cellulose) and Avicel PH-101 substrates, using mass spectrometry analysis. Mass spectra results of Avicel PH-101 and PASC cleavages by purified E7 LPMO expressed in E. coli and in P. pastoris allowed the visualization of compounds corresponding to oxidized and non-oxidized oligosaccharides. Further optimization of reactions will be performed, since it was found only one degree of polymerization (DP 7). This work demonstrated that it is possible to produce the E7 LPMO from T. fusca in the host P. pastoris, and the recombinant protein was shown to be active on cellulose. The approach used in the present work could be an alternative to produce this bacterial LPMO for cellulose cleavage.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • On the formation and role of reactive oxygen species in light-driven LPMO
           oxidation of phosphoric acid swollen cellulose
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      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: 2017-07-23T08:05:19Z
       
  • Unliganded and substrate bound structures of the cellooligosaccharide
           active lytic polysaccharide monooxygenase LsAA9A at low pH
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Kristian E.H. Frandsen, Jens-Christian N. Poulsen, Tobias Tandrup, Leila Lo Leggio
      Lytic polysaccharide monooxygenases (LPMOs) have been found to be key components in microbial (bacterial and fungal) degradation of biomass. They are copper metalloenzymes that degrade polysaccharides oxidatively and act in synergy with glycoside hydrolases. Recently crystallographic studies carried out at pH 5.5 of the LPMO from Lentinus similis belonging to the fungal LPMO family AA9 have provided the first atomic resolution view of substrate-LPMO interactions. The LsAA9A structure presented here determined at pH 3.5 shows significant disorder of the active site in the absence of substrate ligand. Furthermore some differences are also observed in regards to substrate (cellohexaose) binding, although the major interaction with the N-terminal histidine remains unchanged.
      Graphical abstract image

      PubDate: 2017-07-23T08:05:19Z
       
  • RP-UHPLC-UV-ESI-MS/MS analysis of LPMO generated C4-oxidized
           
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      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.
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      PubDate: 2017-07-23T08:05:19Z
       
  • Structural studies of Neurospora crassa LPMO9D and redox partner CDHIIA
           using neutron crystallography and small-angle scattering
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      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 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 LPMO9D (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.
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      PubDate: 2017-07-23T08:05:19Z
       
  • Fast purification method of functional LPMOs from Streptomyces ambofaciens
           by affinity adsorption
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      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.
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      PubDate: 2017-07-23T08:05:19Z
       
  • A novel expression system for lytic polysaccharide monooxygenases
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      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.
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      PubDate: 2017-07-23T08:05:19Z
       
  • Gold(I)-catalyzed synthesis of β-Kdo glycosides using Kdo
           ortho-hexynylbenzoate as donor
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Xuemeng Mi, Qixin Lou, Wenjing Fan, Liqin Zhuang, You Yang
      A gold(I)-catalyzed glycosylation of Kdo with glycosyl ortho-hexynylbenzoate as donor is reported. The couplings of Kdo ortho-hexynylbenzoate with a set of alcohols promoted by PPh3AuOTf afford Kdo glycosides with good β-selectivities. This glycosylation method allows for the synthesis of β-Kdo monosaccharide with a C5 linker at the reducing end for subsequent conjugation to carrier proteins and arrays.
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      PubDate: 2017-07-23T08:05:19Z
       
  • In Memoriam Benito Casu (1927–2016)
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Grégorio Crini, Giangiacomo Torri


      PubDate: 2017-07-23T08:05:19Z
       
  • A comparative study on the activity of fungal lytic polysaccharide
           monooxygenases for the depolymerization of cellulose in soybean spent
           flakes
    • Abstract: Publication date: Available online 18 July 2017
      Source:Carbohydrate Research
      Author(s): Brian C. Pierce, Jane Wittrup Agger, Zhenghong Zhang, Jesper Wichmann, Anne S. Meyer
      Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes capable of the oxidative breakdown of polysaccharides. They are of industrial interest due to their ability to enhance the enzymatic depolymerization of recalcitrant substrates by glycoside hydrolases. In this paper, twenty-four lytic polysaccharide monooxygenases (LPMOs) expressed in Trichoderma reesei were evaluated for their ability to oxidize the complex polysaccharides in soybean spent flakes, an abundant and industrially relevant substrate. TrCel61A, a soy-polysaccharide-active AA9 LPMO from T. reesei, was used as a benchmark in this evaluation. In total, seven LPMOs demonstrated activity on pretreated soy spent flakes, with the products from enzymatic treatments evaluated using mass spectrometry and high performance anion exchange chromatography. The hydrolytic boosting effect of the top-performing enzymes was evaluated in combination with endoglucanase and beta-glucosidase. Two enzymes (TrCel61A and Aspte6) showed the ability to release more than 36% of the pretreated soy spent flake glucose – a greater than 75% increase over the same treatment without LPMO addition.
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      PubDate: 2017-07-23T08:05:19Z
       
  • Characterization of the O-antigen polysaccharide derived from Pantoea
           agglomerans IG1 lipopolysaccharide
    • Abstract: Publication date: 8 September 2017
      Source:Carbohydrate Research, Volume 449
      Author(s): Masahito Hashimoto, Rune Satou, Mami Ozono, Hiroyuki Inagawa, Gen-Ichiro Soma
      A polysaccharide fraction was isolated from the Pantoea agglomerans IG1 lipopolysaccharide (IP-PA1), and its O-antigenic polysaccharide was characterized by chemical analyses and 1D and 2D 1H and 13C NMR spectroscopy. The polysaccharide is composed of linear tetrasaccharide repeating units, consisting of glucose and rhamnose, where 40% of one of the rhamnose residues is substituted with glucose: →2)-α-l-Rhap-(1→6)-α-d-Glcp-(1→2)-[β-d-Glcp-(1→3)]0.4-α-l-Rhap-(1→2)-α-l-Rhap-(1→
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      PubDate: 2017-07-09T04:05:05Z
       
  • Structural characterization of glucosylated lactose derivatives
           synthesized by the Lactobacillus reuteri GtfA and Gtf180 glucansucrase
           enzymes
    • Abstract: Publication date: Available online 8 July 2017
      Source:Carbohydrate Research
      Author(s): Hien T.T. Pham, Lubbert Dijkhuizen, Sander S. van Leeuwen
      Glucansucrase enzymes from lactic acid bacteria are receiving strong interest because of their wide range of gluco-oligosaccharide and polysaccharide products from sucrose, some of which have prebiotic potential. Glucansucrases GtfA and Gtf180 from Lactobacillus reuteri strains are known to convert sucrose into α-glucans with different types of linkages, but also to use other molecules as acceptor substrates. Here we report that incubation of (N-terminally truncated versions of) these enzymes with lactose plus sucrose resulted in synthesis of at least 5 glucosylated lactose products of a degree of polymerization (DP) of 3–4. Only glucansucrase Gtf180-ΔN also produced larger lactose-based oligosaccharides (up to DP9). Structural characterization of the glucosylated lactose products DP3-4 revealed glycosidic bonds other than (α1→4)/(α1→6) typical for GtfA-ΔN and (α1→3)/(α1→6) typical for Gtf180-ΔN: Both GtfA-ΔN and Gtf180-ΔN now introduced a glucosyl residue (α1→3)- or (α1→4)-linked to the non-reducing galactose unit of lactose. Both enzymes also were able to introduce a glucosyl residue (α1→2)-linked to the reducing glucose unit of lactose. These lactose derived oligosaccharides potentially are interesting prebiotic compounds.
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      PubDate: 2017-07-09T04:05:05Z
       
  • Evaluation of hydrogen bond networks in cellulose Iβ and II crystals
           using density functional theory and Car–Parrinello molecular dynamics
    • Abstract: Publication date: Available online 5 July 2017
      Source:Carbohydrate Research
      Author(s): Daichi Hayakawa, Yoshiharu Nishiyama, Karim Mazeau, Kazuyoshi Ueda
      Crystal models of cellulose Iβ and II, which contain various hydrogen bonding (HB) networks, were analyzed using density functional theory and Car–Parrinello molecular dynamics (CPMD) simulations. From the CPMD trajectories, the power spectra of the velocity correlation functions of hydroxyl groups involved in hydrogen bonds were calculated. For the Iβ allomorph, HB network A, which is dominant according to the neutron diffraction data, was stable, and the power spectrum represented the essential features of the experimental IR spectra. In contrast, network B, which is a minor structure, was unstable because its hydroxymethyl groups reoriented during the CPMD simulation, yielding a different crystal structure to that determined by experiments. For the II allomorph, a HB network A is proposed based on diffraction data, whereas molecular modeling identifies an alternative network B. Our simulations showed that the interaction energies of the cellulose II (B) model are slightly more favorable than model II(A). However, the evaluation of the free energy should be waited for the accurate determination from the energy point of view. For the IR calculation, cellulose II (B) model reproduces the spectra better than model II (A).
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      PubDate: 2017-07-09T04:05:05Z
       
  • Sulfated polysaccharides of the Vietnamese brown alga Sargassum aquifolium
           (Fucales, Sargassaceae)
    • Abstract: Publication date: Available online 27 June 2017
      Source:Carbohydrate Research
      Author(s): Maria I. Bilan, Nadezhda E. Ustyuzhanina, Alexander S. Shashkov, Thanh Thi Thu Thuy, Bui Minh Ly, Tran Thi Thanh Van, Bui Van Nguyen, Anatolii I. Usov
      A fucoidan preparation named FSA was isolated from the brown alga Sargassum aquifolium collected from the coastal waters of Vietnam. l-Fucose, d-galactose, d-mannose, d-glucuronic acid, d-xylose, and sulfate were found to be the main constituents of FSA. The preparation was fractionated by anion-exchange chromatography on DEAE-Sephacel eluted stepwise with 0.5, 1.0, 1.5, and 2.0 M NaCl to give four fractions differing in monosaccharide composition and degree of sulfation. Their NMR spectra were too complex to be completely interpreted. Fractions 1.0 M and 1.5 M were analyzed by methylation before and after desulfation. In addition, desulfated 1.0 M was fractionated by anion-exchange chromatography into six fractions according to the uronic acid content. They were characterized by methylation and NMR spectral data, and three structurally different polysaccharides were identified. One of them has a core of alternating 2-linked α-d-Manp and 4-linked β-d-GlcpA residues, about a half of the former bearing single α-l-Fucp or β-d-Xylp at position 3. The second polymer is a (1 → 3)-β-d-glucopyranuronan partially substituted with single β-d-Xylp or single α-l-Fucp at position 4. The third polysaccharide is a xylo(fuco)galactan having a linear core of alternating 4-linked α-d-Gal and 3-linked β-d-Gal residues. The latter bear single β-d-Xylp or a short chain of 4-linked β-d-Xyl, 6-linked β-d-Gal, and variously linked α-l-Fuc. In FSA, these polysaccharides are sulfated at different positions and devoid of regularity. Fractions of FSA possess anticoagulant, cytotoxic, and antitumor activities, which increase with the degree of sulfation. The most sulfated fraction 2.0 M that contains mainly a sulfated fucogalactan, is about half as active as anticoagulant as the standard low-molecular mass heparin (enoxaparin).
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      PubDate: 2017-06-28T16:53:23Z
       
  • Gram scale synthesis of A (type 2) and B (type 2) blood group
           tetrasaccharides through 1,6-anhydro-N-acetyl-β-D-glucosamine
    • Abstract: Publication date: Available online 27 June 2017
      Source:Carbohydrate Research
      Author(s): Tatiana V. Tyrtysh, Elena Yu Korchagina, Ivan M. Ryzhov, Nicolai V. Bovin
      Gram scale synthesis of A (type 2) and B (type 2) tetrasaccharides in the form of 3-aminopropyl glycosides is proposed starting from 3-O-benzoyl-1,6-anhydro-N-acetylglucosamine. Its galactosylation followed by re-protection gave lactosamine derivative with single free 2′OH group in total yield 75%. Standard fucosylation and next run of re-protection in total yield 88% gave a trisaccharide Fuc-Gal-anhydroGlcNAc with single free 3′OH group. Its standard α-galactosylation gave protected B (type 2) tetrasaccharide. For synthesis of correspondent A tetrasaccharide seven different 2-azido-2-deoxygalactosyl (GalN3) donors were tested: 6-O-acetyl-3,4-O-isopropylidene-GalN3 thioglycoside was shown to provide the best yield (89%) and stereoselectivity (α/β = 24:1). Further 1,6-anhydro cycle opening, spacer-arming and complete deprotection resulted in the target 3-aminopropyl glycosides of A (type 2) and B (type 2) tetrasaccharides, yields 87 and 85% correspondingly.
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      PubDate: 2017-06-28T16:53:23Z
       
  • Imaging of protein-specific glycosylation by glycan metabolic tagging and
           in situ proximity ligation
    • Abstract: Publication date: Available online 27 June 2017
      Source:Carbohydrate Research
      Author(s): Xuexia Li, Xuecheng Jiang, Xiaoyan Xu, Chenggang Zhu, Wen Yi
      Glycosylation is an important posttranslational modification, which regulates a number of critical biological processes including cell-cell recognition, signal transduction and disease progression. Probing the glycosylation status on a specific protein of interest enables an in-depth understanding of the role of glycosylation on protein structure and function. However, methods for monitoring protein-specific glycosylation are largely lacking. Here we describe a highly sensitive fluorescence imaging strategy to visualize the protein-specific glycosylation by combining glycan metabolic tagging and in situ proximity ligation (termed GPLA). We demonstrate the visualization of sialylation, fucosylation and GalNAcylation on several important membrane proteins. Notably, the high spatial resolution of this method allows subcellular localization of the glycosylated fraction of the proteins. We further show that our strategy can be applied to image the dimerization of endogenous epidermal growth factor receptor. Thus, our study provides a unique tool to monitor the protein-specific glycosylation in a dynamic cellular context.
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      PubDate: 2017-06-28T16:53:23Z
       
  • Agarose based large molecular systems: Synthesis of fluorescent aromatic
           agarose amino acid nano-conjugates – their pH-stimulated structural
           variations and interactions with BSA
    • Abstract: Publication date: Available online 26 June 2017
      Source:Carbohydrate Research
      Author(s): Atul K. Sharma, Nishith A. Chudasama, Kamalesh Prasad, A.K. Siddhanta
      Two new nano-sized fluorescent 6-amino agarose naphthalic acid half ester derivatives were synthesized (ca.60% yields) employing 1,8- and 2,3-naphthalic acid anhydrides (1,8-AANE, and 2,3-AANE respectively). These large nano molecular frameworks (DLS 3 & 100 nm, and 3 & 152 nm respectively) contains amino, naphthalate half-ester carboxyl groups at the C-6 positions of the 1,3-β-D-galactopyranose moieties of the agarose backbone (overall DS 0.94). Structures were characterized (FT-IR, and 13C & 1H NMR spectrometries). These materials mimicked a large protein conjugate (GPC 123, and 108 kDa) exhibiting pH-responsive conformational variations (optical rotatory dispersion), offering a mixed solubility pattern like a soluble random coil (pH 4–10), and precipitate (pH 2) formation. With bovine serum albumin 1,8- and 2,3-AANE showed complexation, and decomplexation at pH 5.2, and 6.8 respectively. However, they showed decomplexation, and complexation respectively at pH 10 (circular dichroism). These fluorogenic systems may be of prospective utility as chiral sensors and in the realms demanding the virtues of preferential protein bindings.
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      PubDate: 2017-06-28T16:53:23Z
       
  • N-glycan structures of β-HlH subunit of Helix lucorum hemocyanin
    • Abstract: Publication date: Available online 22 June 2017
      Source:Carbohydrate Research
      Author(s): Lyudmila Velkova, Pavlina Dolashka, Jozef Van Beeumen, Bart Devreese
      The carbohydrate structures of molluscan hemocyanins have recently received particular interest due to their specific monosaccharide composition, as well as their immunostimulatory properties and application in clinical studies. For the first time, we investigated N-glycans of the structural subunit β-HlH of hemocyanin isolated from Helix lucorum. In total, 32 different glycans were enzymatically liberated and characterized by tandem mass spectrometry using a Q-Trap mass spectrometer. Our study revealed a highly heterogeneous mixture of glycans with composition Hex3-7HexNAc2-5MeHex0-4Pent0-1Fuc0-1. The oligosaccharide chains are mostly modified at the inner core by β1-2-linked xylose to β-mannose, by α1-6-fucosylation of the innermost GlcNAc residue (the Asn-bound GlcNAc), and by methylation. The glycans of β-HlH mainly contain a terminal MeHex residue; in some cases even two, three or four of these residues occur. Several carbohydrate chains in β-HlH are core-fucosylated without Xyl and also possess a high degree of methylation. This study shows the presence of mono- and bi-antennary N-glycans as well as hybrid type structures with or without core-fucosylation.
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      PubDate: 2017-06-28T16:53:23Z
       
  • Synthesis of S-linked trisaccharide glycal of derhodinosylurdamycin A:
           Discovery of alkyl thiocyanate as an efficient electrophile for
           stereoselective sulfenylation of 2-deoxy glycosyl lithium
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Padam P. Acharya, Kedar N. Baryal, Cristin E. Reno, Jianglong Zhu
      Stereoselective synthesis of S-linked trisaccharide glycal of angucycline antitumor antibiotic derhodinosylurdamycin A is described. The synthesis has been accomplished employing our previously reported umpolung S-glycosylation strategy ― stereoselective sulfenylation of 2-deoxy glycosyl lithium. It was found that sugar-derived thiocyanate was a better electrophile than corresponding asymmetric disulfide in this type of stereoselective sulfenylation.
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      PubDate: 2017-06-21T02:40:05Z
       
  • Structural characterization of wall and lipidated polysaccharides from
           Clostridium perfringens ATCC 13124
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Evgeny Vinogradov, Annie Aubry, Susan M. Logan
      Cell surface polysaccharides produced by C. perfringens ATCC 13124 were analyzed using NMR, chemical and immunological methods. Two distinct polymers were identified. The more abundant PS1 had a structure based on a polymer of β-mannosamine with a number of modifications, including varying levels of substitution at O-6 with PEtN, N-acetylation, and different linkages between monosaccharides. The shortest variant of PS1 represented a lipoteichoic acid. It contained only 1-4-linkages between ManNAc residues, minor branching α-Ribf, and glucosyl-glycerol at the reducing end, which was acylated with linear saturated fatty acids C16, C18, and C20 (dominant). Other non-lipidated variants of PS1 contained less PEtN, no α-Ribf, up to 50% 1-3-linkages, and up to 25% ManN with the free amino group. The minor polysaccharide PS2 had a linear regular structure with a -4-α-Rha-3-β-Gal-4-β-GalNAc3PCho- repeating unit, where PCho indicates phosphocholine.
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      PubDate: 2017-06-21T02:40:05Z
       
  • Structural characterization of the immunostimulatory exopolysaccharide
           produced by Leuconostoc mesenteroides strain NTM048
    • Abstract: Publication date: 7 August 2017
      Source:Carbohydrate Research, Volume 448
      Author(s): Chiaki Matsuzaki, Chikahiro Takagaki, Yusuke Tomabechi, Lennart S. Forsberg, Christian Heiss, Parastoo Azadi, Kenji Matsumoto, Toshihiko Katoh, Koji Hosomi, Jun Kunisawa, Kenji Yamamoto, Keiko Hisa
      The exopolysaccharide (EPS) produced by probiotic Leuconostoc mesenteroides subsp. mesenteroides strain NTM048 has been reported to be an immunostimulant that enhances mucosal IgA production. In this study, we found that intranasal administration of mice with the EPS and an antigen (ovalbumin) resulted in secretion of antigen-specific IgA and IgG in the airway mucosa and the serum, suggesting that the EPS has the adjuvant activity for use with mucosal vaccination. Methylation analysis coupled to GC-MS, and 1D and 2D NMR spectroscopy revealed that 94% of the EPS consists of an α-(1 → 6) glucan containing 4% of 1→3-linked α-glucose branches. To determine structures of minor components, we enzymatically digested the glucan with dextranase and used 2D NMR spectroscopy to identify the remaining polymer as a fructan (or fructans), containing both β-(2 → 6)- and β-(2 → 1)-linked fructofuranose residues. These residues may either enter into separate polymers of each linkage type or form a mixed fructan containing both linkage types.
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      PubDate: 2017-06-21T02:40:05Z
       
  • Hydrogenolytic cleavage of naphthylmethyl ethers in the presence of
           sulfides
    • Abstract: Publication date: Available online 20 June 2017
      Source:Carbohydrate Research
      Author(s): Philip O. Adero, Dean R. Jarois, David Crich
      With the aid of a series of model thioether or thioglycoside containing polyols protected with combinations of benzyl ethers and 2-naphthylmethyl ethers it is demonstrated that the latter are readily cleaved selectively under hydrogenolytic conditions in the presence of the frequently catalyst-poisoning sulfides. These results suggest the possibility of employing 2-naphthylmethyl ethers in place of benzyl ethers in synthetic schemes when hydrogenolytic deprotection is anticipated in the presence of thioether type functionality.
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      PubDate: 2017-06-21T02:40:05Z
       
  • Role of the triple solute/ion/water interactions on the saccharide
           hydration: A volumetric approach
    • Abstract: Publication date: Available online 20 June 2017
      Source:Carbohydrate Research
      Author(s): J. Teychené, H. Roux-De Balmann, S. Galier
      The aim of this study is to further the understanding of the mechanisms that govern the hydration behavior of neutral solutes, with respect to the ions' properties that are present in a solution. For that, a systematic volumetric study of saccharides (xylose, glucose and sucrose), in the presence of various electrolytes (LiCl, NaCl, KCl, Na2SO4, K2SO4, CaCl2, MgCl2, MgSO4) has been carried out with density measurements at 298.15 K. From this data, the standard transfer molar volume of the saccharide Δ V ϕ , S 0 , which characterizes the hydration state of the solute, has been determined. Positive and increasing values of Δ V ϕ , S 0 with increasing electrolyte concentrations were obtained. This indicated the dehydration of the saccharide in the presence of the electrolyte, due to the predominance of saccharide/cation interactions. Concerning the influence of the cation, it was shown that saccharides are more dehydrated in the presence of divalent cations than in the presence of monovalent ones. This is because the interactions are stronger between saccharides and divalent cations, in comparison to those with monovalent cations. For a specific cation valence and molality, regardless of the anion, saccharide dehydration increases according to the following sequences: Li+< Na+< K+ and Mg2+< Ca2+. These saccharide dehydration sequences have been explained by the Gibbs free energy of hydration of the cations, reflecting the cation/water interactions. For a specific cation valence, it was concluded that decreasing cation/water interactions induce the increase of saccharide dehydration. Concerning the influence of the anion, it was also observed that saccharides are more dehydrated in the presence of divalent anions than in the presence of monovalent ones. It was stated that saccharide/cation interactions are modulated by the nature of the anion. The anion impact was again attributed to its capacity to interact with water molecules. It was pointed out that anions with increasing values of Gibbs free energy of hydration cause an increase in saccharide/cation interactions or a decrease in saccharide/anion interactions. Therefore, saccharide dehydration increases.
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      PubDate: 2017-06-21T02:40:05Z
       
  • Elucidating biochemical features and biological roles of Streptomyces
           proteins recognizing crystalline chitin- and cellulose-types and their
           soluble derivatives
    • Abstract: Publication date: Available online 20 June 2017
      Source:Carbohydrate Research
      Author(s): Hildgund Schrempf
      Pioneering biochemical, immunological, physiological and microscopic studies in combination with gene cloning allowed uncovering previously unknown genes encoding proteins of streptomycetes to target crystalline chitin and cellulose as well as their soluble degradation-compounds via binding protein dependent transporters. Complementary analyses provoked an understanding of novel regulators governing transcription of selected genes. These discoveries induced detecting close and distant homologues of former orphan proteins encoded by genes from different bacteria. Grounded on structure-function-relationships, several researchers identified a few of these proteins as novel members of the growing family for lytic polysaccharides monooxygenases. Exemplary, the ecological significance of the characterized proteins including their role to promote interactions among organisms is outlined and discussed.
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      PubDate: 2017-06-21T02:40:05Z
       
  • A quantitative method for analyzing glycome profiles of plant cell walls
    • Abstract: Publication date: Available online 19 June 2017
      Source:Carbohydrate Research
      Author(s): Sivakumar Pattathil, Miles W. Ingwers, Doug P. Aubrey, Zenglu Li, Joseph Dahlen
      Glycome profiling allows for the characterization of plant cell wall ultrastructure via sequential extractions and subsequent detection of specific epitopes with a suite of glycan-specific monoclonal antibodies (mAbs). The data are often viewed as the amount of materials recovered and a coinciding colored heat maps of mAb binding. Interpretation of this data can be considered qualitative in nature as it depends on detecting subtle visual differences in antibody binding strength. Here, we report a mixed model-based quantitative approach for glycome profile analyses, which accounts for the amount of materials recovered and displays the normalized values in revised heatmaps and statistical heatmaps depicting significant differences. The utility of this methodology was demonstrated on a previously published dataset investigating the effects of moisture stress on the roots and needles of Pinus taeda. An annotated R script for the quantitative methodology is included to allow future studies to utilize the same approach.
      Graphical abstract image

      PubDate: 2017-06-21T02:40:05Z
       
  • Structures and gene clusters of the O-antigens of Escherichia albertii O3,
           O4, O6, and O7
    • Abstract: Publication date: Available online 17 June 2017
      Source:Carbohydrate Research
      Author(s): Olesya I. Naumenko, Han Zheng, Sof'ya N. Senchenkova, Hong Wang, Qun Li, Alexander S. Shashkov, Jianping Wang, Yuriy A. Knirel, Yanwen Xiong
      The O-specific polysaccharides (OPSs) called O-antigens were obtained by mild acid degradation of the lipopolysaccharides of Escherichia albertii serotypes O3, O4, O6, and O7 and studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following structure was established for the OPS of E. albertii O4, which, to our knowledge, is unique among known bacterial polysaccharide structures: →2)-α-l-Rhap-(1 → 2)-α-l-Fucp-(1 → 2)-β-d-Galp-(1 → 3)-α-d-GalpNAc-(1 → 3)-β-d-GlcpNAc-(1→ The OPS structure of the strain of E. albertii O7 studied was identical to that of strain LMG 20973 (= Albert 10457), whose structure has been reported earlier (R. Eserstam et al. Eur. J. Biochem. 269 (2002) 3289–3295). E. albertii O3 and O6 shared the OPS structures with Escherichia coli O181 and O3, respectively, except for the lack of O-acetylation in E. albertii O3, which is present in E. coli O181. The gene clusters driving the O-antigen biosynthesis of the E. albertii strains were sequenced, the genes were annotated by comparison with sequences in the available databases, and the predicted functions of the encoded proteins were found to be consistent with the OPS structures established. In accordance with the relatedness of the OPS structures, the O-antigen gene clusters of E. albertii O3 and O6 contain the same genes and have the same organization as those of E. coli O181 and O3, the entire gene clusters being 83% and 98% identical, respectively.
      Graphical abstract image

      PubDate: 2017-06-21T02:40:05Z
       
  • Structure of the LPS O-chain from Fusobacterium nucleatum strain 12230
    • Abstract: Publication date: Available online 16 June 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. It was also found in colorectal cancer tissues and is linked with pregnancy complications, including pre-term and still births. Cell surface structures of the bacterium could be implicated in pathogenesis. Here we report the following structure of the lipopolysaccharide O-chain of F. nucleatum strain 12230: -6-α-d-Glc-4-β-d-GlcNHBu3NHBuA-3-β-d-QuiNAc4NABu- where ABu and HBu indicate (R)-3-aminobutanoyl and (R)-3-hydroxybutanoyl, respectively; all monosaccharides are in the pyranose form.
      Graphical abstract image

      PubDate: 2017-06-21T02:40:05Z
       
  • Synthesis and antimicrobial activity of 6-sulfo-6-deoxy-D-glucosamine and
           its derivatives
    • Abstract: Publication date: Available online 12 June 2017
      Source:Carbohydrate Research
      Author(s): Kornelia Skarbek, Iwona Gabriel, Piotr Szweda, Marek Wojciechowski, Muna A. Khan, Boris Görke, Sławomir Milewski, Maria J. Milewska
      6-Sulfo-6-deoxy-D-glucosamine (GlcN6S), 6-sulfo-6-deoxy-D-glucosaminitol (ADGS) and their N-acetyl and methyl ester derivatives have been synthesized and tested as inhibitors of enzymes catalyzing reactions of the UDP-GlcNAc pathway in bacteria and yeasts. GlcN6S and ADGS at micromolar concentrations inhibited glucosamine-6-phosphate (GlcN6P) synthase of microbial origin. The former was also inhibitory towards fungal GlcN6P N-acetyl transferase, but at millimolar concentrations. Both compounds and their N-acetyl derivatives exhibited antimicrobial in vitro activity, with MICs in the 0.125–2.0 mg mL−1 range. Antibacterial but not antifungal activity of GlcN6S was potentiated by D-glucosamine and a synergistic antibacterial effect was observed for combination of ADGP and a dipeptide Nva-FMDP.
      Graphical abstract image

      PubDate: 2017-06-15T18:20:04Z
       
  • Biochemical and structural characterization of Penicillium purpurogenum
           α-D galactosidase: Binding of galactose to an alternative pocket may
           explain enzyme inhibition
    • Abstract: Publication date: Available online 9 June 2017
      Source:Carbohydrate Research
      Author(s): Luis Morales-Quintana, Carolina Faúndez, Raúl Herrera, Vasni Zavaleta, María Cristina Ravanal, Jaime Eyzaguirre, María Alejandra Moya-León
      The fungus Penicillium purpurogenum degrades plant cell walls by the action of cellulolytic, xylanolytic and pectinolytic enzymes. The α-D-galactosidase is one of the enzymes which may act on pectin degradation. This enzyme has several biotechnological and medical applications. The aim of this work was to better understand the molecular mechanism of α-D-galactosidase from P. purpurogenum (GALP1). For this purpose, a gene coding for the enzyme was identified from the fungal genome and heterologously expressed in Pichia pastoris. The enzyme belongs to glycosyl hydrolase family 27. The protein of 435 amino acids has an optimum pH and temperature for activity of 5.0 and 50 °C, respectively. The KM for p-nitrophenyl-α-D-galactopyranoside (GalαpNP) is 0.138 mM. The enzyme is inhibited by GalαpNP at concentrations higher than 1 mM, and by the product galactose. A kinetic analysis of product inhibition shows that it is of mixed type, suggesting the presence of an additional binding site in the enzyme. To confirm this hypothesis, a structural model for GALP1 was built by comparative modelling methodology, which was validated and refined by molecular dynamics simulation. The data suggest that galactose may bind to an enzyme alternative pocket promoting structural changes of the active site, thus explaining its inhibitory effect. In silico site-directed mutagenesis experiments highlighted key residues involved in the maintenance of the alternative binding site, and their mutations for Ala predict the formation of proteins which should not be inhibited by galactose. The availability of an α-galactosidase with different kinetic properties to the existent proteins may be of interest for biotechnological applications.
      Graphical abstract image

      PubDate: 2017-06-10T14:31:12Z
       
  • Rumpictusoide A: Unusual 9,10-anthraquinone glucoside from Rumex pictus
           Forssk
    • Abstract: Publication date: Available online 9 June 2017
      Source:Carbohydrate Research
      Author(s): Walaa A. El-Kashak, Abdelsamed I. Elshamy, Tarik A. Mohamed, Abd El-Nasser G. El Gendy, Ibrahim A. Saleh, Akemi Umeyama
      A new 8-ionized hydroxylated 9,10-anthraquinone namely, 1-hydroxy-3-methyl-9,10-anthraquinone-6-O-β-D-glucopyranoside-8-olate (Rumpictusoide A, 1) along with five known flavonoids, apigenin 7-O-β-D-glucoside (2), vitexin (3), quercetin 3-O-β-D-glucouronide (4), orientin (5), and isorientin (6) were isolated from Rumex pictus. The structures of isolated compounds were identified by the extensive spectroscopic techniques such as, UV, FT-IR, 1D, 2D NMR, NOESY and HR-FAB-ESI-MS. The ionized hydroxyl group in the new anthraquinone (1) was rarely found for anthraquinone glycosides isolated from natural sources. All the isolated compounds were found inactive against influenza A virus infection. Compounds 2–6 exhibited significant antioxidant activity against DPPH and against ABTS+. The alcoholic extract exhibited moderate activity while the new anthraquinone 1 showed the lowest activity against both assays.
      Graphical abstract image

      PubDate: 2017-06-10T14:31:12Z
       
  • Synthesis of a glucosylated α-S-galactosylceramide as potential
           immunostimulant
    • Abstract: Publication date: Available online 1 June 2017
      Source:Carbohydrate Research
      Author(s): Lei Zhang, Cian Mc Carthy, Xiangming Zhu
      Synthesis of a glucosylated α-S-galactosylceramide (1), a potential immunostimulant, was achieved starting from D-galactose. Both O- and S-glycosidic linkages were constructed in highly stereoselective way, and the synthetic strategy could be extended to the synthesis of other α-S-GalCer analogues.
      Graphical abstract image

      PubDate: 2017-06-04T14:25:05Z
       
  • Studies on the O-specific polysaccharide of the lipopolysaccharide from
           the Pseudomonas mediterranea strain C5P1rad1, a bacterium pathogenic of
           tomato and chrysanthemum
    • Abstract: Publication date: Available online 1 June 2017
      Source:Carbohydrate Research
      Author(s): Evelina L. Zdorovenko, Alessio Cimmino, Guido Marchi, Alexander S. Shashkov, Mario Fiori, Yuriy A. Knirel, Antonio Evidente
      An O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Pseudomonas mediterranea strain C5P1rad1, the causal agents of tomato pith necrosis and Chrysanthemum stem rot, and studied by one- and two-dimensional 1H and 13C NMR spectroscopy. The following structure of the trisacharide repeating unit of the OPS was established, which, to our knowledge, is unique among the known bacterial polysaccharide structures: →4)-β-d-ManpNAc3NAcA-(1 → 4)-β-d-ManpNAc3NAcA-(1 → 3)-α-d-QuipNAc4NAc-(1→ where QuiNAc4NAc and ManNAc3NAcA indicate 2,4-diacetamido-2,4,6-trideoxyglucose and 2,3-diacetamido-2,3-dideoxymannuronic acid, respectively. Pre-treatment of leaves with LPS or OPS preparations at 250 and 50 μg mL−1 did not inhibit development of a hypersensitivity reaction induced by P. mediterranea C5P1rad1 on tobacco, tomato and chrysanthemum plants. The same preparations at 250 μg mL−1 partially prevented elicitation of the hypersensitivity reaction by Pseudomonas syringae KVPT7RC on chrysanthemum but not tobacco and tomato.
      Graphical abstract image

      PubDate: 2017-06-04T14:25:05Z
       
  • Synthesis of (±)-myo-inositol 4-methylenephosphonate via Rh-Catalyzed
           hydrogenation of vinylphosphonate
    • Abstract: Publication date: Available online 29 May 2017
      Source:Carbohydrate Research
      Author(s): Tatsuo Okauchi, Shuya Nakamura, Kouta Tsubaki, Momoko Asakawa, Mitsuru Kitamura
      Phosphatidylinositol phosphate (PIP) synthetase is a promising target for the development of new anti-mycobacterium compounds. We previously reported that myo-inositol 1-methylenephosphonate showed inhibitory activity against PIP synthetase. Herein, we report the synthesis of unprotected myo-inositol 4-methylenephosphonate, a constitutional isomer of myo-inositol 1-methylenephosphonate and found that the stereoselective hydrogenation of vinylphosphonate proceeded via Rh catalysis.
      Graphical abstract image

      PubDate: 2017-06-01T02:00:46Z
       
  • The effects of diatom pore-size on the structures and extensibilities of
           single mucilage molecules
    • Abstract: Publication date: Available online 26 May 2017
      Source:Carbohydrate Research
      Author(s): Immanuel Sanka, Eko Agus Suyono, Parvez Alam
      Diatoms secrete extracellular polymeric substances (EPS), or mucilage, around the cell wall that may serve to aid in motility and form a discrete layer that may help maintain thicker layers of EPS that have a greater role in adhesion. Mucilage molecules adhere to the diatom frustules, which are biosilica skeletons that develop from the diatom cell walls. Here, molecular dynamics methods were used to determine the characteristics of mucilage molecules as a function of pore size; notably 1,4-α-D-galacturonic acid, 1,4-β-glucuronic acid and 1,4-β-D-mannuronic acid. These uronic acids differ from each other in structure and extensibility as a function of their folding characteristics. Here, we find that when overlain upon a pore, mucilage molecules try to return to their native folded states but are restrained by their interactions with the silica surfaces. Furthermore, the extensibility of mucilage molecules over pore spaces affects the extent of mechanical energy required to straighten them. As such, different EPS molecules will affect sliding, friction and adhesion to subsequent layers of EPS in different ways. We conclude that higher EPS extensibility is homonymous with higher adhesive or frictive resistance since the molecules will be able to strain more before they reach the most extended (and thus rigid) conformation. The research herein is applicable to modern engineering as it yields insight into the biomimetic design of molecules and surfaces for improved adhesion or motility.
      Graphical abstract image

      PubDate: 2017-06-01T02:00:46Z
       
  • Structures of the K35 and K15 capsular polysaccharides of Acinetobacter
           baumannii LUH5535 and LUH5554 containing amino and diamino uronic acids
    • Abstract: Publication date: Available online 25 May 2017
      Source:Carbohydrate Research
      Author(s): Alexander S. Shashkov, Bin Liu, Johanna J. Kenyon, Anastasiya V. Popova, Mikhail M. Shneider, Sof'ya N. Senchenkova, Nikolay P. Arbatsky, Konstantin A. Miroshnikov, Lei Wang, Yuriy A. Knirel
      Capsular polysaccharides were isolated from A. baumannii LUH5535 (K35 CPS) and LUH5554 (K15 CPS) and studied by 1D and 2D 1H and 13C NMR spectroscopy. The CPSs were found to consist of linear tetrasaccharide repeats (K units) containing 2-acetamido-2-deoxy-d-galacturonic acid (K35) or 2,3-diacetamido-2,3-deoxy-d-glucuronic acid (K15) and 2,4-diacetamido-2,4,6-trideoxy-d-glucose (both CPSs). The K35 unit includes three O-acetyl groups on different GalNAcA residues. A. baumannii LUH5535 and LUH5554 carry the KL35 and KL15 gene clusters, respectively, and putatively assigned functions of genes in these clusters were consistent with the CPS structures established.
      Graphical abstract image

      PubDate: 2017-06-01T02:00:46Z
       
  • Glycoform of a newly identified pollen allergen, Cha o 3, from
           Chamaecyparis obtusa (Japanese cypress, Hinoki)
    • Abstract: Publication date: Available online 24 May 2017
      Source:Carbohydrate Research
      Author(s): Toshihiro Osada, Megumi Maeda, Chinatsu Tanabe, Kaori Furuta, Christopher J. Vavricka, Eiji Sasaki, Mitsuhiro Okano, Yoshinobu Kimura
      Cha o 3 is a newly found glycosylated allergen from Chamaecyparis obtusa (Japanese cypress) pollen. The deduced amino acid sequence of Cha o 3 indicates that this glycoallergen contains a cellulase domain and a number of putative N-glycosylation sites. However, the structures of N -glycans linked to Cha o 3 remain to be determined. In this study, therefore, we analyzed the glycoform of Cha o 3 and found that this glycoallergen carries exclusively plant complex-type N-glycans; major structures were GlcNAc2Man3Xyl1Fuc1GlcNAc2 (39%), Gal1Fuc1GlcNAc2Man3Xyl1Fuc1GlcNAc2 (14%), and Gal2Fuc2GlcNAc2Man3Xyl1Fuc1GlcNAc2 (25%). The glycoform of Cha o 3 bearing the Lea epitope is similar to those of Cry j1, Jun a 1, or Cup a 1, major glycoallergens in cedar or cypress pollens, and the predominant occurrence of GlcNAc2Man3Xyl1Fuc1GlcNAc2 is a common structural feature of glycoallergens from Cupressaceae pollens.
      Graphical abstract image

      PubDate: 2017-05-26T14:21:43Z
       
  • Structural studies of the O-specific polysaccharide from detergent
           degrading bacteria Pseudomonas putida TSh-18
    • Abstract: Publication date: Available online 22 May 2017
      Source:Carbohydrate Research
      Author(s): Elena N. Sigida, Yuliya P. Fedonenko, Alexander S. Shashkov, Evelina L. Zdorovenko, Vladimir V. Ignatov, Yuriy A. Knirel
      An O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of bacteria Pseudomonas putida TSh-18, capable of degrading non-ionogenic technical detergents. The polysaccharide was found to contain a rarely occurring sugar derivative 4,6-dideoxy-4-[(R)-3-hydroxybutanoylamino]-d-galactose [d-Fucp4N(RHb)]. Sugar and methylation analyses, Smith degradation, solvolysis with CF3CO2H, and 1H and 13C NMR spectroscopy enabled elucidation of the following structure of the branched trisaccharide repeating units of the polysaccharide: Image 2
      Graphical abstract image

      PubDate: 2017-05-26T14:21:43Z
       
  • Synthesis of oligo-fructopyranoside with difructopyranosyl
           N-phenyltrifluoroacetimidate donor
    • Abstract: Publication date: Available online 22 May 2017
      Source:Carbohydrate Research
      Author(s): Hongliang Zhang, Hengtao Wang, Qiulong Xu, Rui Lu, Yunhua Cao, Zhefeng Wang, Pingping Tang, Feng Lin, Yingxia Li
      The hexa-fructopyranoside was synthesized with N-phenyltrifluoroacetimidate glycosylation. The synthesis was achieved by regioselective glycosylation on the 1-OH of fructopyranosyl acceptor. Fructosyl oligosaccharides were elongated with β-(2 → 1)-difructopyranosyl unit in every two steps, without any further protection/deprotection step. This work proved N-phenyltrifluoroacetimidate glycosylation a practical method for oligo-fructopyranoside synthesis.
      Graphical abstract image

      PubDate: 2017-05-26T14:21:43Z
       
  • Stereospecific synthesis of methyl
           2-amino-2-deoxy-(6S)-deuterio-α,β-d-glucopyranoside and methyl
           2,6-diamino-2,6-dideoxy-(6R)-deuterio-α,β-d-glucopyranoside: Side chain
           conformations of the 2-amino-2-deoxy and
           2,6-diamino-2,6-dideoxyglucopyranosides
    • Abstract: Publication date: Available online 19 May 2017
      Source:Carbohydrate Research
      Author(s): Takayuki Kato, Andrea Vasella, David Crich
      The stereospecifically labeled 6-monodeuterio methyl 2,6-diamino-2,6-dideoxy-α- and β- d-glucopyranosides were synthesized with a view to determining their side chain conformations. NMR studies in D2O at pH 5 and pH 11 reveal both anomers to adopt very predominantly the gt conformation consistent with the gauche conformation of 2-aminoethanol and its acetate salt. In contrast, as also revealed with the help of stereospecifically-labelled monodeuterio iostopomers, the methyl 2-amino-2-deoxy-α- and β- d-glucopyranosides are an approximately 1:1 mixture of gg and gt conformers as is found in glucopyranose itself.
      Graphical abstract image

      PubDate: 2017-05-21T15:38:34Z
       
  • Oxidation of 3,5-di-C-(per-O-acetylglucopyranosyl)phloroacetophenone in
           the synthesis of hydroxysafflor yellow A
    • Abstract: Publication date: Available online 13 May 2017
      Source:Carbohydrate Research
      Author(s): Toshiyuki Suzuki, Mitsuo Ishida, Toshihiro Kumazawa, Shingo Sato
      In the synthesis of the main yellow pigment hydroxysafflor yellow A (HSYA), that is present in safflower petals, the key compound 4-(S)-2-acetyl-4,6-di-C-(per-O-acetyl-β-D-glucosyl)-3,4-dihydroxy-5-methoxycyclohexa-2,5-dienone (11b) was diastereoselectively synthesized in an overall yield of 18% from di-C-β-D-glucosylphloroacetophenone per-O-acetate (8).
      Graphical abstract image

      PubDate: 2017-05-16T18:15:05Z
       
 
 
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