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  Subjects -> CHEMISTRY (Total: 898 journals)
    - ANALYTICAL CHEMISTRY (55 journals)
    - CHEMISTRY (632 journals)
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CHEMISTRY (632 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 28)
ACS Catalysis     Hybrid Journal   (Followers: 46)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 27)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 42)
ACS Nano     Hybrid Journal   (Followers: 308)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription  
ACS Synthetic Biology     Hybrid Journal   (Followers: 25)
Acta Chemica Iasi     Open Access   (Followers: 5)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     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: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 6)
Advanced Functional Materials     Hybrid Journal   (Followers: 60)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 75)
Advances in Chemical Science     Open Access   (Followers: 19)
Advances in Chemistry     Open Access   (Followers: 24)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Environmental Chemistry     Open Access   (Followers: 7)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 27)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Polymer Science     Hybrid Journal   (Followers: 45)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
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: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 8)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 68)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 32)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 16)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 181)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 259)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
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: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 25)
Applied Surface Science     Hybrid Journal   (Followers: 34)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 3)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 378)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
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: 2)
Biomacromolecules     Hybrid Journal   (Followers: 23)
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: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 139)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 90)
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: 1)
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: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 25)
Carbon     Hybrid Journal   (Followers: 71)
Catalysis for Sustainable Energy     Open Access   (Followers: 8)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 12)
Cellulose     Hybrid Journal   (Followers: 10)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 21)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 75)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 205)
Chemical Science     Open Access   (Followers: 28)
Chemical Technology     Open Access   (Followers: 34)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 57)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 33)
Chemistry & Industry     Hybrid Journal   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 168)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Hybrid Journal   (Followers: 268)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
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: 11)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Cogent Chemistry     Open Access   (Followers: 2)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
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: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal   (Followers: 1)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 9)
Current Science     Open Access   (Followers: 73)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 2)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 4)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)

        1 2 3 4 | Last

Journal Cover
Carbohydrate Research
Journal Prestige (SJR): 0.617
Citation Impact (citeScore): 2
Number of Followers: 25  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0008-6215 - ISSN (Online) 0008-6215
Published by Elsevier Homepage  [3157 journals]
  • Chemo-enzymatic synthesis of p-nitrophenyl β-D-galactofuranosyl
           disaccharides from Aspergillus sp. fungal-type galactomannan
    • Abstract: Publication date: Available online 11 January 2019Source: Carbohydrate ResearchAuthor(s): Ryo Ota, Yumi Okamoto, Christopher J. Vavricka, Takuji Oka, Emiko Matsunaga, Kaoru Takegawa, Hiromasa Kiyota, Minoru Izumi β-d-Galactofuranose (Galf) is a component of polysaccharides and glycoconjugates. There are few reports about the involvement of galactofuranosyltransferases and galactofuranosidases (Galf-ases) in the synthesis and degradation of galactofuranose-containing glycans. The cell walls of filamentous fungi in the genus Aspergillus include galactofuranose-containing polysaccharides and glycoconjugates, such as O-glycans, N-glycans, and fungal-type galactomannan, which are important for cell wall integrity. In this study, we investigated the synthesis of p-nitrophenyl β-d-galactofuranoside and its disaccharides by chemo-enzymatic methods including use of galactosidase. The key step was selective removal of the concomitant pyranoside by enzymatic hydrolysis to purify p-nitrophenyl β-d-galactofuranoside, a promising substrate for β-d-galactofuranosidase from Streptomyces species.Graphical abstractImage 1
       
  • Characterization of CBM36-containing GH11 endoxylanase NtSymX11 from the
           hindgut metagenome of higher termite Nasutitermes takasagoensis displaying
           prominent catalytic activity
    • Abstract: Publication date: Available online 11 January 2019Source: Carbohydrate ResearchAuthor(s): Marina Kitamoto, Gaku Tokuda, Hirofumi Watanabe, Manabu Arioka Symbionts in the gut of termites are expected to be large sources of enzymes involved in lignocellulose degradation, but their biotechnological potential has not been fully explored. In this study, we expressed, purified, and biochemically characterized a glycoside hydrolase family 11 xylanase, NtSymX11, from a symbiotic bacterium of the higher termite, Nasutitermes takasagoensis. NtSymX11 is a multimodular enzyme consisting of a catalytic domain and two tandem carbohydrate-binding modules (CBM36). The pH and temperature optima of NtSymX11 were pH 6.0 and 40 °C, respectively. By comparing the properties of full-length and truncated variants of NtSymX11, it was shown that CBM36 decreases the enzyme stability at acidic pH and high temperature. The main products from xylohexaose and various xylan substrates were X1-X3 xylooligosaccharides. Analysis of kinetic parameters indicated that NtSymX11 displays an outstanding catalytic performance when compared to other reported xylanases, and CBM36 enhances the activity by increasing the affinity to the substrate. Addition of Ca2+ boosted the activity of full-length enzyme, but not the truncated variant lacking the CBM, against the insoluble substrate, suggesting that CBM36 plays a role in the Ca2+-dependent increase of catalytic efficiency.Graphical abstractImage 1
       
  • Bivalent glycoconjugates based on
           1,5-diazabicyclo[3.3.0]octa-3,6-diene-2,8-dione (“bimane”) as a
           central scaffold
    • Abstract: Publication date: Available online 8 January 2019Source: Carbohydrate ResearchAuthor(s): Tamás Szabó, Attila Bényei, László Szilágyi The heteroaromatic fused diazabicyclic “bimane” ring system, discovered four decades ago, is endowed with remarkable chemical and photophysical properties. No carbohydrate derivatives of bimanes have, however, been described thus far. Here we report on the syntheses of a range of bimanes decorated with various glycosyl residues. Mono- and disaccharide residues were attached to syn- or anti-bimane central cores via thio-, disulfido- or selenoglycosidic linkages to obtain novel fluorescent or nonfluorescent glycoconjugates. Cu(I)-catalyzed cycloaddition of glycosyl azides to a bimane diethynyl derivative furnished further bivalent glycoconjugates with sugar residues linked to the central bimane core via 1,2,3-triazole rings. We have determined the crystal and molecular structures of several glycosylated and non-glycosylated bimanes and report fluorescence data for the new compounds.Graphical abstractImage 1
       
  • Treatment of recalcitrant crystalline polysaccharides with lytic
           polysaccharide monooxygenase relieves the need for glycoside hydrolase
           processivity
    • Abstract: Publication date: Available online 7 January 2019Source: Carbohydrate ResearchAuthor(s): Anne Grethe Hamre, Anne-Grethe Skaarberg Strømnes, Daniel Gustavsen, Gustav Vaaje-Kolstad, Vincent G.H. Eijsink, Morten Sørlie Processive glycoside hydrolases associate with recalcitrant polysaccharides such as cellulose and chitin and repeatedly cleave glycosidic linkages without fully dissociating from the crystalline surface. The processive mechanism is efficient in the degradation of insoluble substrates, but comes at the cost of reduced enzyme speed. We show that less processive chitinase variants with reduced ability to degrade crystalline chitin, regain much of this ability when combined with a lytic polysaccharide monooxygenase (LPMO). When combined with an LPMO, several less processive chitinase mutants showed equal or even increased activity on chitin compared to the wild-type. Thus, LPMOs affect the need for processivity in polysaccharide degrading enzyme cocktails, which implies that the composition of such cocktails may need reconsideration.Graphical abstractImage 1
       
  • Structural analysis of a novel lipooligosaccharide (LOS) from
           Rhodobacter azotoformans
    • Abstract: Publication date: Available online 7 January 2019Source: Carbohydrate ResearchAuthor(s): Yoshimi Kanie, Yoshiki Yamaguchi, Akiyoshi Hayashi, Jun Uzawa, Makoto Hatakeyama, Yasuhiro Hidaka, Nobuhiro Toda, Shinichiro Nakamura, Osamu Kanie Lipopolysaccharides (LPS) are components of the Gram-negative bacterial cell surface that stimulate the host innate immune system through the Toll-like receptor (TLR) 4–MD-2 complex. Rhodobacter sp. have been reported to produce LPS that lack endotoxic activity, and instead act as antagonists of other endotoxins. In this report, we focused on LPS, especially the lipooligosaccharides (LOS) fraction produced by Rhodobacter azotoformans that shows production of IL-8, but has an inverse correlation with IL-6 production. We analyzed their molecular structure by using mass spectrometry and nuclear magnetic resonance spectroscopy and report a novel LOS consisting of a shorter glycan structure of glucuronic acid but not heptoses. A novel glycan structure, Glcα(1 → 4)GlcAα(1 → 4)KDOα(2 → 4)[Glcα(1 → 5)]KDOα(2 → 6)[4-phosphate]GlcNβ(1 → 6) GlcNα1-phosphate, was proposed using NMR methods. The structure was consistent with one obtained based on MS. The MS analysis further revealed the existence of structural variation caused by extension with hexoses. The acyl composition in lipid A was suggested to contain three C14 fatty acyl chains (3-OH-14:0 or 3-oxo-14:0 at N2 of GlcN-1, 3-OH-14:0 at N2 of GlcN-2, that carried another 14:1 Δ7 on its β-hydroxyl group) and two C10 fatty acyl chains (3-OH-10:0 at O3 of both GlcN), which are same as those found in lipid A from Rhodobacter spheroides.Graphical abstractImage 1
       
  • H+activation&rft.title=Carbohydrate+Research&rft.issn=0008-6215&rft.date=&rft.volume=">Palladium catalyzed synthesis of sugar-fused indolines via C(sp2)–H/NH
           activation
    • Abstract: Publication date: Available online 4 January 2019Source: Carbohydrate ResearchAuthor(s): Ashish Kumar Verma, Ande Chennaiah, Sateesh Dubbu, Yashwant D. Vankar A simple Pd(OAc)2 catalyzed strategy for the synthesis of sugar-fused indolines from 2-N-oxalylamido-2-deoxy-C-aryl glycosides is reported by utilizing N-oxalylamido group as an auxiliary via C(sp2)–H/NH Activation. The reaction is successfully applied on glucose as well as galactose derived differently substituted 2-N-oxalylamido-2-deoxy-C-aryl glycosides to give sugar-fused indolines in moderate to good yields. The utility of this strategy in the synthesis of sugar-fused indoles is also described.Graphical abstractImage 1
       
  • Probing peptide substrate specificities of N-glycosyltranferase isoforms
           from different bacterial species
    • Abstract: Publication date: Available online 30 December 2018Source: Carbohydrate ResearchAuthor(s): Qingyun Meng, Kun Li, Yongheng Rong, Qizheng Wu, Xunlian Zhang, Yun Kong, Min Chen N-glycosyltransferase (NGT) is responsible for transferring hexose monosaccharides to the asparagine side chain of proteins and polypeptides in the consensus sequon (N-(X≠P)-T/S) with nucleotide-activated sugars as donor substrates. Here, we expressed and purified four different N-glycosyltransferases derived from diverse bacteria, including Actinobacillus pleuropneumoniae, Aggregatibacter aphrophilus, Kingella kingae and Bibersteinia trehalosi, and measured their catalytic activities of four synthesized peptides via in vitro glycosylation assays. RP-HPLC and mass spectrometry were used to identify and quantify the glycopeptide formation by distinct NGT isoforms. We then analyzed and compared the glycosylation efficiencies of different peptides for these four NGT isoforms, which showed distinct substrate selectivities. We sought to probe peptide specificities among various NGT isoforms, which could broaden the application of NGT-catalyzed N-glycosylation of a variety of therapeutic proteins.Graphical abstractImage 1
       
  • Purification and biochemical characterization of a novel
           acido-halotolerant and thermostable endochitinase from Melghiribacillus
           thermohalophilus strain Nari2AT
    • Abstract: Publication date: Available online 29 December 2018Source: Carbohydrate ResearchAuthor(s): Sara Mohamed, Khelifa Bouacem, Sondes Mechri, Nariman Ammara Addou, Hassiba Laribi-Habchi, Marie-Laure Fardeau, Bassem Jaouadi, Amel Bouanane-Darenfed, Hocine Hacène An extracellular acido-thermostable endochitinase (called ChiA-Mt45) from thermohalophilic Melghiribacillus thermohalophilus strain Nari2AT gen. nov. sp. nov., was purified and biochemically characterized. The maximum chitinase activity recorded after 48-h of incubation at 55 °C was 9000 U/mL. Pure enzyme was obtained after heat treatment (20 min at 90 °C) followed by sequential column chromatographies on fast performance liquid chromatography (FPLC) and high performance liquid chromatography (HPLC). Based on MALDI–TOF/MS analysis, the purified enzyme is a monomer with a molecular mass of 45201.10 Da. The 27 residue NH2-terminal sequence of the enzyme showed high homology with Bacillus GH-18 chitinases family. The optimum pH and temperature values for chitinase activity were pH 3.5 and 90 °C, respectively. In addition, the enzyme was halotolerant and can be classified as an extremozyme. The pure enzyme was completely inhibited by p-chloromercuribenzoic acid (p-CMB) and N-ethylmaleimide (NEM). Its Km and kcat values were 0.253 mg colloidal chitin/mL and 47000 s−1, respectively. Interestingly, its catalytic efficiency was higher than those of chitinases ChiA-Hh59 from Hydrogenophilus hirchii KB-DZ44 and chitodextrinase from Streptomyces griseus, and N-acetyl-β-glucosaminidase from Trichoderma viride. The studied chitinase exhibited high activity towards colloidal chitin, chitin azure, glycol chitin, while it did not hydrolyse chitibiose and amylose. Additionally, thin-layer chromatography (TLC) analysis from chitin-oligosaccharides showed that ChiA-Mt45 acted as an endosplitting enzyme. Overall, the chitinase ChiA-Mt45 may have great potential for the enzymatic degradation of chitin.Graphical abstractImage 1
       
  • Synthesis of a hexasaccharide repeating unit of the cell wall
           polysaccharide of Bifidobacterium animalis subsp. lactis LKM512
    • Abstract: Publication date: Available online 25 December 2018Source: Carbohydrate ResearchAuthor(s): Pradip Shit, Anup Kumar Misra A convergent synthesis of the hexasaccharide as its 2-aminoethyl glycoside corresponding to the repeating unit of the cell wall polysaccharide of Bifidobacterium animalis subsp. lactis LKM512 has been achieved applying a [4 + 2] glycosylation strategy. The disaccharide thioglycoside donor was prepared by combining a d-galactofuranosyl thioglycoside with another l-rhamnosyl thioglycoside acceptor. The yields of the individual glycosylation steps were highly satisfactory with excellent stereo outcome. An α-glycosidic linkage of the d-galactofuranosyl moiety in the hexasaccharide was achieved in very good yield.Graphical abstractImage 1
       
  • A unique structural distribution pattern discovered for the cerebrosides
           from starfish Asterias amurensis
    • Abstract: Publication date: Available online 24 December 2018Source: Carbohydrate ResearchAuthor(s): Ryosuke Yamaguchi, Yoshimi Kanie, Osamu Kanie, Yoshitaka Shimizu Cerebroside is an important family of the mono-glycosylated ceramides involved in the larger family of glycosphingolipid and sulfatide. Cerebroside is synthesized from ceramide by the transfer of glucose from UDP-glucose, and degraded back to ceramide, which plays an important role at the epidermis protecting interior of the body as a barrier. Because cerebroside is regarded as the source molecule of ceramide and is amphiphilic in nature, cerebroside is considered valuable as the ingredient of cosmetic lotion.Various sources can be considered as raw material of cerebrosides. Starfish is considered as one of such potent source. However, the structure of the ceramide part of cerebroside is not fully investigated. Therefore, the individual structures of cerebroside molecules need to be identified including sphingosine and fatty acyl group composition to assess the potential of the molecule.We investigated and determined the structures of cerebrosides in starfish Asterias amurensis using LC-MS, GC-MS, tandem mass spectrometry (MS/MS), and 1H NMR. We also discovered a characteristic structure distribution that was divided into three major groups: 1) a group composed of a relatively long sphingosine (C22) and a short length of fatty acyl group (less than C16), 2) a group composed of a typical C18 sphingosine and long fatty acyl groups (greater than C23), and 3) a group composed of C18 sphingosine and fatty acyl groups with their length less than C18. The calculated Log P values of cerebrosides ranging from 9 to 11 covered about 80% of the molecules that were in the range of those used in cosmetics, thus showing the potential usefulness of starfish Asterias amurensis as a source of raw material for cerebrosides.Graphical abstractImage 1
       
  • NMR solution geometry of saccharides containing the
           6-O-(α-D-glucopyranosyl)-α/β-D-glucopyranose (isomaltose) or
           6-O-(α-D-galactopyranosyl)-α/β-D-glucopyranose (melibiose) core
    • Abstract: Publication date: Available online 22 December 2018Source: Carbohydrate ResearchAuthor(s): Amelia Watson, Sven Hackbusch, Andreas H. Franz The solution geometries of D-Glcp, Me-D-Glcp, 6-O-Me-D-Glcp, Me-6-O-Me-D-Glcp, D-Glcp-(α-1,6)-D-Glcp (isomaltose), D-Glcp-(α-1,6)-D-Glcp-(α-1,6)-D-Glcp (isomaltotriose), D-Galp-(α-1,6)-D-Glcp (melibiose), D-Galp-(α-1,6)-D-Glcp-(α-1,2)-D-Fruf (raffinose), and D-Galp-(α-1,6)-D-Galp-(α-1,6)-D-Glcp-(α-1,2)-D-Fruf (stachyose) in water are described by NMR spectroscopy, molecular dynamic simulations and quantum mechanical calculations. Overall, a change in anomeric configuration at the reducing end and/or anomeric substitution (methylation) changed the conformational space of the terminal CH2OH group significantly. Conformational analysis of the free monosaccharides matched literature results very well. Dihedral angle histograms weighted against published Karplus equations yielded excellent matches of experimental J-values in some cases but significant deviations in other. The anomeric hemiacetal configuration appeared to have a significant remote influence on the conformational space of the α-1,6-glycosidic linkage. Rigid glycosidic φ-conformations (g+) combined with mostly st-conformations for glycosidic ψ-angles from computations matched experimental nuclear Overhauser enhancements in all cases. While the investigated Glcp-α-1,6-Glcp linkages were nearly identical in φ/ψ-conformation, differences were apparent in the Galp-α-1,6-Galp linkage of stachyose. Of twenty-one crystal structures, a total of fourteen had ligand conformations corresponding to the most abundant or second-most abundant solution geometry determined in this study.Graphical abstractImage 1
       
  • ADP-heptose: A new innate immune modulator
    • Abstract: Publication date: Available online 19 December 2018Source: Carbohydrate ResearchAuthor(s): Xinyuan Hu, Chunhua Yang, Peng George Wang, Gao-Lan Zhang Lipopolysaccharide (LPS) is a well-known pathogen-associated molecular pattern (PAMP) produced by gram-negative bacteria. Previous studies showed that a key metabolic intermediate in LPS biosynthesis, d-glycero-β-d-manno-heptose 1,7-bisphosphate (HBP), could activate the NF-κB pathway and trigger the innate immune responses. However, it was unclear whether HBP could be a novel PAMP and its pattern recognition receptor (PRR) is not fully understood. Very recently, the Shao group reported that another key metabolic intermediate in LPS biosynthesis, ADP-heptose, could be transported into mammalian cells and bind with ALPK1 (alpha-kinase 1), which leads to a series of strong immune responses. These findings broaden our understanding on bacterial metabolites as a new type of PAMP and these small molecules hold great potential to be applied in the development of novel immune modulators. This minireview focuses on the roles of ADP-heptose related metabolites in innate immunity.Graphical abstractImage 1
       
  • Structure determination of Streptococcus suis serotypes 7 and 8 capsular
           polysaccharides and assignment of functions of the cps locus genes
           involved in their biosynthesis
    • Abstract: Publication date: Available online 18 December 2018Source: Carbohydrate ResearchAuthor(s): Guillaume Goyette-Desjardins, Evgeny Vinogradov, Masatoshi Okura, Daisuke Takamatsu, Marcelo Gottschalk, Mariela Segura Streptococcus suis serotypes 7 and 8 are counted among the top six S. suis serotypes causing clinical disease in pigs. Yet, limited information is available on these serotypes. Since S. suis serotyping system is based upon capsular polysaccharide (CPS) antigenicity and the CPS is considered a major virulence factor for encapsulated pathogens, here we determined for the first time the chemical compositions and structures of serotypes 7 and 8 CPSs. Chemical and spectroscopic data gave the following repeating unit sequences: [3)L-Rha(α1-P-2)D-Gal(α1-4)D-GlcA(β1-3)D-FucNAc4N(α1-]n for serotype 7 and [2)L-Rha(α1-P-4)D-ManNAc(β1-4)D-Glc(α1-]n for serotype 8. As serotype 8 CPS is identical to Streptococcus pneumoniae type 19F CPS, dot-blot analyses showed a strong reaction of the 19F polysaccharide with reference anti-S. suis serotype 8 rabbit serum. A correlation between S. suis serotypes 7 and 8 sequences and genes of those serotypes’ loci encoding putative glycosyltransferases and polymerases responsible for the biosynthesis of the repeating units was tentatively established. Knowledge of CPS structure and composition will contribute to better dissect the role of this bacterial component in the pathogenesis of the disease caused by S. suis serotypes 7 and 8.Graphical abstractImage 1
       
  • Structure of the O-specific polysaccharide from a halophilic bacterium
           Halomonas ventosae RU5S2EL
    • Abstract: Publication date: Available online 15 December 2018Source: Carbohydrate ResearchAuthor(s): Ibrahim M. Ibrahim, Elena N. Sigida, Maxim S. Kokoulin, Yulia P. Fedonenko, Svetlana A. Konnova Halomonas ventosae RU5S2EL, a halophilic Gram-negative bacterium isolated from salt sediments of lake Elton (Russia), was cultivated and the lipopolysaccharide was extracted by the Westphal procedure. The O-specific polysaccharide (OPS) was obtained by mild acid hydrolysis of the lipopolysaccharide and was studied by sugar analysis along with 1H and 13C NMR spectroscopy, including 1H,1H COSY, TOCSY, ROESY, 1H,13C HSQC, and HMBC experiments as well as Smith degradation. The OPS was found to consist of branched pentasaccharide repeating units of the following structure:Image 2Graphical abstractImage 1
       
  • Chiron approach from D-mannitol to access a diastereomer of the reported
           structure of an acetogenin; an amide alkaloid; and a sex pheromone
    • Abstract: Publication date: Available online 14 December 2018Source: Carbohydrate ResearchAuthor(s): Sandip Chatterjee, Avrajit Manna, Ipsita Chakraborty, Tanurima Bhaumik A short, simple and convenient chiron approach to (3R,4S,5R)-(−)-3,5-dihydroxy-4-decanolide, a hitherto unknown diastereomer of the reported structure of a naturally occurring acetogenin, (+)-polyporolide has been accomplished starting from a commercially available, inexpensive chiral-pool molecule D-(+)-mannitol in nine efficient steps. An advanced intermediate synthesized from D-(+)-mannitol in six steps toward this end was further employed successfully to access two different natural products bearing two contiguous stereogenic centers. As a result, first chiron approach to formal total synthesis of an amide alkaloid, (4R,5R,2E)-4,5-dihydroxy-1-(piperidin-1-yl)dec-2-en-1-one and total synthesis of a male sex pheromone in parasitic Hymenoptera, (4R,5R)-(−)-5-hydroxy-4-decanolide have also been achieved.Graphical abstractImage 1
       
  • The characterisation of a galactokinase from Streptomyces
           coelicolor
    • Abstract: Publication date: Available online 14 December 2018Source: Carbohydrate ResearchAuthor(s): Tessa Keenan, Rhys Mills, Emily Pocock, Darshita Budhadev, Fabio Parmeggiani, Sabine Flitsch, Martin Fascione Promiscuous galactokinases (GalKs), which catalyse the ATP dependent phosphorylation of galactose in nature, have been widely exploited in biotechnology for the rapid synthesis of diverse sugar-1-phosphates. This work focuses on the characterisation of a bacterial GalK from Streptomyces coelicolor (ScGalK), which was overproduced in Escherichia coli and shown to phosphorylate galactose. ScGalK displayed a broad substrate tolerance, with activity towards Gal, GalN, Gal3D, GalNAc, Man and L-Ara. Most interestingly, ScGalK demonstrated a high activity over a broad pH and temperature range, suggesting that the enzyme could be highly amenable to multi-enzyme systems.Graphical abstractImage 1
       
  • Probing deoxysugar conformational preference: A comprehensive
           computational study investigating the effects of deoxygenation
    • Abstract: Publication date: Available online 12 December 2018Source: Carbohydrate ResearchAuthor(s): Alison E. Vickman, Nicola L.B. Pohl Deoxysugars are intrinsic components in a number of antibiotics, antimicrobials, and therapeutic agents that often dictate receptor binding, improve efficacy, and provide a diverse toolbox in modifying glycoconjugate function due to an extensive number of unique isomers and inherent conformational flexibility. Hence, this work provides a comprehensive examination of the conformational effects associated with deoxygenation of the pyranose ring. Both the location and degree of deoxygenation were evaluated by interrogating the energetic landscape for a number of mono- and dideoxyhexopyranose derivatives using DFT methods (M05-2X/cc-pVTZ(-f)). Both anomeric forms and in some cases, the alternate chair form, have been investigated in the gas phase. As was documented in a preceding study, variation of the C-6 oxidation state has been shown to affect the anomeric preference of select glucose stereoisomers. Similar results were also observed for several deoxysugar isomers in this work, wherein the alternate anomer was favored upon reduction to the 6-deoxyhexose derivative or oxidation to the hexonic acid. Additionally, comparison of relative Gibbs free energies revealed C-3 deoxygenation imparts greater instability compared to C-2 or C-4 deoxygenation, as indicated by an increase in free energy for 3-deoxysugars. A polarizable continuum solvation model was also applied to empirically validate theoretical results for several deoxysugars, wherein good agreement with both carbon (σ = 1.6 ppm) and proton (σ = 0.20 ppm) NMR shifts was observed for the majority of isomers. Solvated and gas phase anomeric ratios were also calculated and compared favorably to reported literature values, although some discrepancies are noted.Graphical abstractImage 1
       
  • Substrate binding versus escape dynamics in a pH-Affected fungal
           beta-glucosidase revealed by molecular dynamics simulations
    • Abstract: Publication date: Available online 11 December 2018Source: Carbohydrate ResearchAuthor(s): Mina Solhtalab, David F. Flannelly, Ludmilla Aristilde The cellulolytic ability of fungal species is important to both natural and engineered biocycling of plant matter. One essential step is the conversion of cellobiose into glucose catalyzed by beta-glucosidases. Mutagenesis studies have implicated altering the substrate binding pocket to influence the pH-activity profile of this enzyme. However, structural understanding of the pH-affected substrate binding environment is lacking. Here we conducted molecular dynamics simulations of fully hydrated TrBgl2, a beta-glucosidase of Trichoderma reesei, equilibrated at its optimal pH (pH 6) and two unfavorable pHs (pH 5 and pH 7.5). We identified structural arrangement of specific residues that facilitated substrate escape from the catalytic site at pH 5 but locked the bound substrate in an unfavorable orientation at pH 7.5. For comparative analysis, we also performed simulations of a mutated TrBgl2 with previously demonstrated improved catalysis as a function of pH. We captured the responsible conformational changes in the engineered substrate binding pocket.Graphical abstractImage 1
       
  • Structures of cell-wall glycopolymers of Lactobacillus rhamnosus
           BIM B-1039
    • Abstract: Publication date: Available online 10 December 2018Source: Carbohydrate ResearchAuthor(s): Evelina L. Zdorovenko, Alexandra A. Kadykova, Alexander S. Shashkov, Danuta T. Plotnikova, Elena P. Kiseleva, Galina I. Novik, Yuriy A. Knirel Glycopolymers of two types were isolated from the cell wall of Lactobacillus rhamnosus BIM B-1039 by stepwise extraction with cold and hot 10% aq CCl3CO2H followed by anion-exchange gel chromatography. The following structures of the glycopolymers were established by sugar analysis, Smith degradation and 1D and 2D NMR spectroscopy:Graphical abstractImage 1
       
  • Facile chemoenzymatic synthesis of Lewis a (Lea) antigen in gram-scale and
           sialyl Lewis a (sLea) antigens containing diverse sialic acid forms
    • Abstract: Publication date: Available online 9 December 2018Source: Carbohydrate ResearchAuthor(s): Nova Tasnima, Hai Yu, Xuebin Yan, Wanqing Li, An Xiao, Xi Chen An efficient streamlined chemoenzymatic approach has been developed for gram-scale synthesis of Lewis a angtigen (LeaβProN3) and a library of sialyl Lewis a antigens (sLeaβProN3) containing different sialic acid forms. Intially, commercially available inexpensive N-acetylglucosamine (GlcNAc) was converted its N′-glycosyl p-toluenesulfonohydrazide in one step. Followed by chemical glycosylation, GlcNAcβProN3 was synthesized using this protecting group-free method in high yield (82%). Sequential one-pot multienzyme (OPME) β1–3-galactosylation of GlcNAcβProN3 followed by OPME α1–4-fucosylation reactions produced target LeaβProN3 in gram-scale. Introducing structurally diverse sialic acid forms was successfully achieved using a OPME sialylation reation containing a sialic acid aldolase, a CMP-sialic acid synthetase, and Pasteurella multocida α2–3-sialyltransferase (PmST1) mutant PmST1 M144D to form sLeaβProN3 containing naturally occurring or non-natural sialic acid forms in preparative scales.Graphical abstractImage 1
       
  • Synthesis of nortropane alkaloid calystegine B2 from methyl
           α-D-xylopyranoside
    • Abstract: Publication date: Available online 7 December 2018Source: Carbohydrate ResearchAuthor(s): Emilie N. Underlin, Henrik H. Jensen A new synthetic route for formation of a central cycloheptanone intermediate leading to the nortropane alkaloid calystegine B2 is described. The approach installs the desired ketone functionality directly in a ring-closing metathesis step. The target compound was prepared over 10 steps from commercially available methyl α-D-xylopyranoside.Graphical abstractImage 1
       
  • A novel and environmental friendly synthetic route for hydroxypyrrolidines
           using zeolites
    • Abstract: Publication date: Available online 4 December 2018Source: Carbohydrate ResearchAuthor(s): A. Fan, G.K. Chuah, Stephan Jaenicke A critical step in the synthesis of the hydroxypyrrolidines, 1,4-dideoxy-1,4-imino-l-lyxitol and 1,4-dideoxy-1,4-imino-d-lyxitol, from the corresponding d-sugars is the synthesis of O-methyl 2,3-O-isopropylidenepentofuranoses. Instead of applying homogeneous catalysis process with conventional inorganic acid catalysts like HCl and HClO4, it was found that heterogeneous catalysis using zeolites could be used for the one-pot synthesis of O-methyl 2,3-O-isopropylidenepentofuranoses directly from d-sugars, MeOH and acetone at mild condition. The best catalyst was H-beta zeolite containing a Si/Al molar ratio of 150, where a yield of>83% was obtained. The overall yields of the five-step procedure to 1,4-dideoxy-1,4-imino-l-lyxitol and 1,4-dideoxy-1,4-imino-d-lyxitol were 57% and 50%, respectively. This synthetic procedure has several advantages such as competitive overall yield, reduced number of steps, and mild reaction conditions. Furthermore, the zeolite catalyst can be easily recovered from the reaction mixture and reused with no loss of activity.Graphical abstractImage 1
       
  • Stereoselective synthesis and antiproliferative activity of the isomeric
           sphinganine analogues
    • Abstract: Publication date: Available online 28 November 2018Source: Carbohydrate ResearchAuthor(s): Miroslava Čonková, Miroslava Martinková, Jozef Gonda, Dominika Jacková, Martina Bago Pilátová, Daniel Kupka, Dávid Jáger A flexible synthetic approach to biologically active sphingoid base-like compounds with a 3-amino-1,2-diol framework was achieved through a [3,3]-sigmatropic rearrangement and late stage olefin cross-metathesis as the key transformations. The stereochemistry of the newly created stereogenic centre was assigned via a single crystal X-ray analysis of the (4S,5R)-5-(hydroxymethyl)-4-vinyloxazolidine-2-thione. In order to rationalise the observed stereoselectivity of the aza-Claisen rearrangement, DFT calculations were carried out. The targeted isomeric sphingoid bases were screened in vitro for anticancer activity on a panel of seven human malignant cell lines. Cell viability experiments revealed that C17-homologues are more active than their C12 congeners.Graphical abstractImage 1
       
  • Strategies for chemoenzymatic synthesis of carbohydrates
    • Abstract: Publication date: Available online 24 November 2018Source: Carbohydrate ResearchAuthor(s): Wanqing Li, John B. McArthur, Xi Chen Carbohydrates are structurally complex but functionally important biomolecules. Therefore, they have been challenging but attractive synthetic targets. While substantial progress has been made on advancing chemical glycosylation methods, incorporating enzymes into carbohydrate synthetic schemes has become increasingly practical as more carbohydrate biosynthetic and metabolic enzymes as well as their mutants with synthetic application are being identified and expressed for preparative and large-scale synthesis. Chemoenzymatic strategies that integrate the flexibility of chemical derivatization with enzyme-catalyzed reactions have been extremely powerful. Briefly summarized here are our experience on developing one-pot multienzyme (OPME) systems and representative chemoenzymatic strategies from others using glycosyltransferase-catalyzed reactions for synthesizing diverse structures of oligosaccharides, polysaccharides, and glycoconjugates. These strategies allow the synthesis of complex carbohydrates including those containing naturally occurring carbohydrate postglycosylational modifications (PGMs) and non-natural functional groups. Combining with facile purification schemes, the access to the diverse space of carbohydrate structures can be automated and will not be limited to specialists.Graphical abstractImage 1
       
  • N-acetyltransferases from three different organisms displaying distinct
           selectivity toward hexosamines and N-terminal amine of peptides
    • Abstract: Publication date: Available online 22 November 2018Source: Carbohydrate ResearchAuthor(s): Peiru Zhang, Pei Liu, Yangyang Xu, Yulu Liang, Peng George Wang, Jiansong Cheng N-acetyltransferases are a family of enzymes that catalyze the transfer of the acetyl moiety (COCH3) from acetyl coenzyme A (Acetyl-CoA) to a primary amine of acceptor substrates from small molecules such as aminoglycoside to macromolecules of various proteins. In this study, the substrate selectivity of three N-acetyltransferases falling into different phylogenetic groups was probed against a series of hexosamines and synthetic peptides. GlmA from Clostridium acetobutylicum and RmNag from Rhizomucor miehei, which have been defined as glucosamine N-acetyltransferases, were herein demonstrated to be also capable of acetylating the free amino group on the very first glycine residue of peptide in spite of varied catalytic efficiency. The human recombinant N-acetyltransferase of Naa10p, however, prefers primary amine groups in the peptides as opposed to glucosamine. The varied preference of GlmA, RmNag and Naa10p probably arose from the divergent evolution of these N-acetyltransferases. The expanded knowledge of acceptor specificity would as well facilitate the application of these N-acetyltransferases in the acetylation of hexosamines or peptides.Graphical abstractImage 1
       
  • Development of a colorimetric PNGase activity assay
    • Abstract: Publication date: Available online 16 November 2018Source: Carbohydrate ResearchAuthor(s): Ting Wang, Shen-Li Zheng, Li Liu, Josef Voglmeir PNGases are crucial targets and valuable tools in analyzing asparagine-linked carbohydrate moieties (N-glycans) of glycoproteins. Activity tests of PNGases have been little improved since their discovery four decades ago, and still rely on observing deglycosylation patterns of glycoproteins or glycopeptides using SDS-PAGE or HPLC analysis. These techniques cannot be easily adapted for automated sampling and high-throughput procedures. Herein, we describe a PNGase activity assay which relies on the conversion of WST-1, a yellowish, water-soluble tetrazolium dye (sodium 2-(4-Iodophenyl)-3-(4-nitro-phenyl)-5-(2,4-disulfophenyl)-2H-tetrazolate). In this work, we showed that WST-1 could be reduced into a blue formazan dye by N-glycans, which were enzymatically released from glycoprotein substrates. After optimization of the assay conditions, the robustness of the method was challenged by quantifying the activity of various PNGase isoforms at different purification stages using a microwell plate reader. Furthermore, the assay could be used to obtain steady-state kinetics of PNGase H+ wild-type and mutant variants, which showed significant differences in their enzymatic reaction rates. The simplicity and robustness of this method might be of benefit for the detection of PNGase activity in routine applications of large amounts of samples.Graphical abstractImage 1
       
  • A versatile synthesis of αGalCer and its analogues exploiting a cyclic
           carbonate as phytosphingosine 3,4-diol protecting group
    • Abstract: Publication date: Available online 15 November 2018Source: Carbohydrate ResearchAuthor(s): Luigi Panza, Federica Compostella, Daniela Imperio A convenient synthetic strategy to αGalCer and some relevant analogues by using a handily protected phytosphingosine is reported here. The conversion of the phytosphingosine amino group to azide and the protection of 3,4-diol as cyclic carbonate group, cleavable in mild basic conditions but resistant to acidic treatment, afforded quickly an excellent glycosyl acceptor. Its glycosylation with a proper galactosyl donor, gave a versatile intermediate in high yield and excellent stereoselectivity. To demonstrate the potentiality of the intermediate, three immunologically relevant compounds were chosen as model targets: αGalCer, dansyl alpha-galactosylceramide and 7DW8-5. These products were easily obtained in few steps and high yields to validate the synthetic route.Graphical abstractImage 1
       
  • Lewis acid-catalysed nucleophilic opening of a bicyclic hemiaminal
           followed by ring contraction: Access to functionalized L-idonojirimycin
           derivatives
    • Abstract: Publication date: Available online 13 November 2018Source: Carbohydrate ResearchAuthor(s): N. Auberger, B. Onfroy, N. Fontelle, Q. Foucart, Y. Blériot The Lewis acid-catalyzed nucleophilic opening of a D-gluco-configured bicyclic hemiaminal has been examined. Several Lewis acids and silylated nucleophiles have been screened allowing the introduction of acetophenone, phosphonate or nitrile at the pseudoanomeric position in satisfactory yields and high 1,2 trans stereoselectivities. Their skeletal rearrangement triggered by the N-benzyl anchimeric assistance provided the corresponding L-ido-configured piperidines displaying various functional groups at C-6 position in good yield.Graphical abstractImage 1
       
  • Molecular design of potent, hydrophilic tyrosinase inhibitors based on the
           natural dihydrooxyresveratrol skeleton
    • Abstract: Publication date: Available online 13 November 2018Source: Carbohydrate ResearchAuthor(s): Yuri Tanaka, Marina Suzuki, Yuka Kodachi, Ken-ichi Nihei In this study, dihydrooxyresveratrol glucosides 3–6 were synthesized for the first time to the best of our knowledge by the Wittig reaction and Schmidt glycosylation as key steps for the purpose of developing novel hydrophilic tyrosinase inhibitors. Results obtained from inhibitory studies revealed 50% inhibitory concentration (IC50) values of 12.80 μM and 2.63 μM for 4-resorcinol glucosides 3 and 4, respectively. The IC50 value of 4 was approximately 4 times greater than that of kojic acid, which is a typical tyrosinase inhibitor. In contrast, 5-resorcinol glucosides 5 and 6 exhibited tyrosinase-inhibitory activity; however their IC50s were not estimated within 100 μM. These results suggested that the discovering 4-resorcinol structure of dihydrooxyresveratrol glucoside is crucial for inducing potent tyrosinase-inhibitory activity.Graphical abstractImage 1
       
  • Synthesis of novel triazole-derived glycopeptides as analogs of
           α-dystroglycan mucins
    • Abstract: Publication date: Available online 11 November 2018Source: Carbohydrate ResearchAuthor(s): Marcelo Fiori Marchiori, Giulia Pompolo Iossi, Leandro Oliveira Bortot, Marcelo Dias-Baruffi, Vanessa Leiria Campo α-Dystroglycan (α-DG) mucins are essential for maintenance of the structural and functional stability of the muscle fiber and, when hypoglycosylated, they are directly involved in pathological processes such as dystroglycanopathies. Thus, this work reports the synthesis of the novel 1,2,3-triazole-derived glycosyl amino acids αGlcNAc-1-O-triazol-2Manα-ThrOH (1) and Gal-β1,4-αGlcNAc-1-O-triazol-2Manα-ThrOH (2), followed by solid-phase assembly to get the corresponding glycopeptides NHAcThrVal[αGlcNAc-1-triazol-2Manα]ThrIleArgGlyOH (3) and NHAcThrVal[Gal-β1,4-αGlcNAc-1-triazol-2Manα]ThrIleArgGlyOH (4) as analogs of α-DG mucins. The glycosyl amino acids 1 (72%) and 2 (35%) were synthesized by Cu(I)-assisted 1,3-dipolar azide-alkyne cycloaddition reactions (CuAAC) between the azide-glycosyl amino acid αManN3-FmocThrOBn (5) and the corresponding alkyne-functionalyzed sugars 2′-propynyl-αGlcNAc (6) and 2′-propynyl-Gal-β1,4-αGlcNAc (7), followed by hydrogenation reactions. Subsequently, glycopeptides 3 (23%) and 4 (12%) were obtained by solid phase synthesis, involving sequential couplings of Fmoc-protected amino acids or the glycosyl amino acids 1 and 2, followed by cleavage from resin, N-acetylation and O-deacetylation (NaOMe) reactions. Lastly, enzymatic galactosylation of glycopeptide 3 with bovine β-1,4-GalT showed that it was not a substrate for this enzyme, which could be better elucidated by docking simulations with β-1,4-GalT.Graphical abstractImage 1
       
  • Synthesis of C-β-D-glucopyranosyl derivatives of some fused azoles for
           the inhibition of glycogen phosphorylase
    • Abstract: Publication date: Available online 7 November 2018Source: Carbohydrate ResearchAuthor(s): Eszter Szennyes, Éva Bokor, Tibor Docsa, Ádám Sipos, László Somsák Annulated C-β-d-glucopyranosyl heterocycles were synthesized and tested as inhibitors of glycogen phosphorylase. 2-(β-d-Glucopyranosyl)-1H-imidazo[4,5-b]pyridine was formed by ring-closure of O-perbenzoylated C-β-d-glucopyranosyl formic acid with 2,3-diaminopyridine in the presence of triphenylphosphite. Cyclisations of bromomethyl 2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl ketone with a set of 2-aminoheterocycles resulted in constitutionally reversed C-β-d-glucopyranosyl imidazoles fused by pyridine, pyrimidine, thiazole, 1,3,4-thiadiazole, benzothiazole and benzimidazole. O-Debenzoylation of the above compounds was effected by standard transesterification to get the test compounds. The 1H-imidazo[4,5-b]pyridine proved to be a low micromolar inhibitor (Ki = 21.1 μM) of rabbit muscle glycogen phosphorylase b, while the other heterocycles displayed weak or no inhibition against the same enzyme.Graphical abstractImage 1
       
  • Structure elucidation and gene cluster annotation of the O-antigen of
           Vibrio cholerae O100 containing two rarely occurred amino sugar
           derivatives
    • Abstract: Publication date: Available online 5 November 2018Source: Carbohydrate ResearchAuthor(s): Andrei V. Perepelov, Xi Guo, Andrei V. Filatov, Alexander S. Shashkov, Sofia N. Senchenkova, Bin Li O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Vibrio cholerae O100 and studied by component analyses and 1D and 2D NMR spectroscopy. The following structure of the O-polysaccharide was established:→3)-β-d-QuipNAc4N(dHh)-(1 → 3)-α-d-Fucp4N(RHb)-(1 → 3)-α-l-FucpNAc-(1→where Hb and dHh indicate 3-hydroxybutanoyl and 3,5-dihydroxyhexanoyl, respectively. The O-antigen gene cluster of V. cholerae O100 has been sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the OPS structure.Graphical abstractImage 1
       
  • Chemoenzymatic radiosynthesis of 2-deoxy-2-[18F]fluoro-D-trehalose
           ([18F]-2-FDTre): A PET radioprobe for In vivo tracing of trehalose
           metabolism
    • Abstract: Publication date: Available online 4 November 2018Source: Carbohydrate ResearchAuthor(s): Santiago Peña-Zalbidea, Ashley Y.-T. Huang, Herbert W. Kavunja, Beatriz Salinas, Manuel Desco, Christopher Drake, Peter J. Woodruff, Juan J. Vaquero, Benjamin M. Swarts Trehalose analogues bearing fluorescent and click chemistry tags have been developed as probes of bacterial trehalose metabolism, but these tools have limitations with respect to in vivo imaging applications. Here, we report the radiosynthesis of the 18F-modified trehalose analogue 2-deoxy-2-[18F]fluoro-D-trehalose ([18F]-2-FDTre), which in principle can be used in conjunction with positron emission tomography (PET) imaging to allow in vivo imaging of trehalose metabolism in various contexts. A chemoenzymatic method employing the thermophilic TreT enzyme from Thermoproteus tenax was used to rapidly (15–20 min), efficiently (70% radiochemical yield; ≥ 95% radiochemical purity), and reproducibly convert the commercially available radiotracer 2-deoxy-2-[18F]fluoro-D-glucose ([18F]-2-FDG) into the target radioprobe [18F]-2-FDTre in a single step; both manual and automated syntheses were performed with similar results. Cellular uptake experiments showed that radiosynthetic [18F]-2-FDTre was metabolized by Mycobacterium smegmatis but not by various mammalian cell lines, pointing to the potential future use of this radioprobe for selective PET imaging of infections caused by trehalose-metabolizing bacterial pathogens such as M. tuberculosis.Graphical abstractImage 1
       
  • Enzymatic synthesis of non-natural trisaccharides and galactosides;
           Insights of their interaction with galectins as a function of their
           structure
    • Abstract: Publication date: Available online 3 November 2018Source: Carbohydrate ResearchAuthor(s): Cecilia Porciúncula González, Alejandro J. Cagnoni, Karina V. Mariño, Carolina Fontana, Patricia Saenz-Méndez, Gabriela Irazoqui, Cecilia Giacomini Galectins are a family of carbohydrate-recognizing proteins that by interacting with specific glycoepitopes can mediate important biological processes, including immune cell homeostasis and activation of tolerogenic circuits. Among the different members of this family, Galectin 1 and 3 have shown pro-tumorigenic effects, being overexpressed in numerous neoplasic diseases, proving to be relevant in tumor immune escape, tumor progression and resistance to drug-induced apoptosis. Thus, generation of specific glycosides that could inhibit their pro-tumorigenic ability by blocking their carbohydrate recognition domain is one of the current major challenges in the field. Considering that galectin-ligand binding strength is closely related to the ligand structure, analysis of this relationship provides valuable information for rational design of high-affinity ligands that could work as effective galectin inhibitors. Taking profit of the ability of glycosidases to catalyze transglycosylation reactions we achieved the enzymatic synthesis of β-d-Galp-(1 → 6)-β-d-Galp-(1 → 4)-d-Glcp(2), a mixture of β-d-Galp-(1 → 6)-β-d-Glcp-(1 → 4)-d-Glcp(5) and β-d-Galp-(1 → 3)-β-d-Glcp-(1 → 4)-d-Glcp(6), and finally benzyl β-d-galactopyranoside (9), with reaction yields between 16 and 27%. All the galactosides were purified, and characterized using 1H and 13C nuclear magnetic resonance spectroscopy. Docking results performed between the synthesized compounds and human Galectin 1 (hGal-1) and human Galectin 3 (hGal-3) showed that the replacement of a glucose moiety linked to the terminal galactose with a galactose moiety, decreases the affinity for these galectins. Moreover, regarding the interglycosidic bond the most favorable β-Gal linkage seems to be β(1 → 4) followed by β(1 → 3) and β(1 → 6) for hGal-1, and β(1 → 4) followed by β(1 → 6) and β(1 → 3) for hGal-3. These results were in accordance with the IC50 values obtained with in vitro solid phase inhibition assays. Therefore, docking results obtained in this work proved to be a very good approximation for predicting binding affinity of novel galactosides.Graphical abstractImage 1
       
  • Recent advances in reagent-controlled stereoselective/stereospecific
           glycosylation
    • Abstract: Publication date: Available online 22 October 2018Source: Carbohydrate ResearchAuthor(s): Hui Yao, Minh Duy Vu, Xue-Wei Liu The formation of O-glycosidic linkage is arguably one of the most important topics in glycoscience due to the prevalence of O-glycosides in nature. Great efforts have been devoted to this field by many carbohydrate chemists to develop stereoselective/stereospecific glycosylation methodologies. Although glycosyl donor- and acceptor-controlled strategies have significantly progressed, the tedious design and pre-synthesis of substrates could not be avoided. On the other hand, reagent-controlled glycosylation can overcome these challenges and produce the desired selectivity by only altering external factors such as concentration, reagents or other reaction conditions. This mini-review discusses selected recent novel methodologies on reagent-mediated stereo-controlled glycosylation in the last decade, classified by the types of glycosyl donors.Graphical abstractImage 1
       
 
 
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