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Carbohydrate Research

Zhihua Chai, Lixiao Ma, Ruiting Meng, Shan Liu, Yanxia Wang
Gold nanoparticles (AuNPs) were prepared by a solvothermal method using sodium alginate (SA) as both, the reductant and stabilizer. The formation of SA-AuNPs was confirmed by UV-Vis spectroscopy, transmission electron microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy. SA-AuNPs were functionalized with fluorescent 3-(dansylamino)phenylboronic acid (DAPB) moieties, through interactions between boronic acids and diol groups. The fluorescence resonance energy transfer from DAPB to AuNPs quenched the fluorescence of DAPB...
February 7, 2019: Carbohydrate Research
Yuri Asami, Yuka Kawaguchi, Yoshimi Kanie, Hajjaj Abdu-Allah, Katsuhiko Suzuki, Osamu Kanie
Trimethylsilylation of the anomeric hydroxyl groups of tetra-O-benzyl and tetra-O-acetyl galactopyranoses was investigated. Stereoselective formation of β-trimethylsilyl glycoside (β-TMS glycoside) of benzyl protected compound was achieved using N-trimethylsilyl diethylamine. In the course of the investigation of the selective synthesis of TMS galactosides using TMS-imidazole, we observed the formation of an intermediate, which was converted predominantly into α-TMS glycoside after silica gel column chromatography...
January 30, 2019: Carbohydrate Research
Jose O Previato, Evguenii Vinogradov, Maria Alice Esteves Silva, Priscila A V Oliveira, Leonardo M Fonseca, Emmanuel Maes, Lucia Mendonça-Previato
Glucuronoxylomannogalactans (GXMGals) are characteristic capsular polysaccharides produced by the opportunistic fungus C. neoformans, which are implicated in cryptococcal virulence, via impairment of the host immune response. We determined for the first time the structure of a lipoglucuronomannogalactan (LGMGal), isolated from the surface of a mutant C. neoformans carrying a deletion in the UDP-GlcA decarboxylase gene. Monosaccharide composition and methylation analyses, as well as nuclear magnetic resonance spectroscopy were employed in discerning the structure...
January 29, 2019: Carbohydrate Research
Manuel Gintner, Yuko Yoneda, Christoph Schmölzer, Christian Denner, Hanspeter Kählig, Walther Schmid
Legionaminic acid and 4-epi-legionaminic acid are 5,7-diacetamido nonulosonic acids and are assumed to play a crucial role in the virulence of Legionella pneumophila, the causative agent of Legionnaires' disease. Moreover, they are ideal target motifs for the development of vaccines and pathogen detection. Herein, we present a versatile de novo synthesis of legionaminic acid and 4-epi-legionaminic acid. Starting from simple d-serine, the C9 -backbone is built up by two CC-bond formation reactions. First, the protected d-serine motif is elongated utilizing a highly stereoselective nitroaldol reaction to give a C6 -precursor of desired d-rhamno configuration...
January 23, 2019: Carbohydrate Research
Weidong Shang, Bin He, Dawen Niu
Carbohydrates play important roles in many physiological and pathological events. The preparation of the derivatives and conjugates of carbohydrates is often needed to help interrogate and exploit their biological properties. Owning to their structural complexity, one major challenge in the derivatization of carbohydrates is to control site-selectivity, that is, to selectively modify one hydroxyl group in the presence of many others. In recent years, ligand controlled transition-metal catalysis has been employed in the site-selective modification of glycosides, resulting in methodologies that enable efficient and direct syntheses of carbohydrates derivatives...
January 22, 2019: Carbohydrate Research
Andrei V Perepelov, Xiaodan Li, Cong Xu, Andrei V Filatov, Alexander S Shashkov, Sofia N Senchenkova, Bin Liu
The O-polysaccharide (O-antigen) of Vibrio cholerae O14 was studied using chemical analyses and 1D and 2D NMR spectroscopy. The following structure of the repeating unit of the O-antigen was established: where GlcpN(SHb) indicates 2-deoxy-2-[(S)-3-hydroxybutanoylamino]-d-glucose. We found that Vibrio cholerae O14 is similar to that of O-polysaccharide of Azospirillum brasilense S17, which has been reported earlier. Moreover, we predicted functions of all the genes in the O-antigen gene cluster according to the structure established...
January 21, 2019: Carbohydrate Research
Miyuki Yamabe, Akira Fujita, Kunihiro Kaihatsu, Yasuhito Ebara
Natural sialic acid-modified compounds are capable of targeting influenza virus hemagglutinin (HA). However, these compounds have limited inhibitory effect because natural O-glycoside bond in these compounds are prone to be cleaved by neuraminidase (NA) on the surface of viruses. In this study, we synthesized NA-resistant sialoside that included unnatural S-glycoside bonds and modified this sialoside on a three-way junction (3WJ) DNA to display complementary distribution to its binding sites on a HA trimer...
January 21, 2019: Carbohydrate Research
Oyunjargal Tumurbaatar, Surina Bo, Oyundelger Ganzorig, Kensuke Miyazaki, Takashi Yoshida
The N-glycans in Toxicodendron vernicifluum (Rhus vernicifera) lacquer laccase was elucidated for the first time through a combination of enzymatic digestion and subsequent mass spectrometry measurements using LC-MS/MS and MALDI-TOF MS. Lacquer laccase was isolated from a Japanese lacquer acetone powder from consecutive Sephadex C-50 and DEAE A-50 column chromatography. Trypsin and chymotrypsin digestions of the lacquer laccase resulted in a mixture of peptides and N-glycopeptides, which were treated with peptide-N-glycosidases and then Nα -(aminooxyacetyl)tryptophanylarginine methyl ester (aoWR) to give the aoWR-labelled N-glycans...
January 14, 2019: Carbohydrate Research
Karolina Gaweda, Wojciech Plazinski
The article is devoted to the problem of molecular modeling of tautomeric and epimeric equilibria in aqueous solutions of unfunctionalized d-aldo- and d-ketohexoses. We have applied the computational protocol proposed in our previous article [Gaweda, Plazinski, Phys. Chem. Chem. Phys., 2017, 19, 20760-20772, doi:10.1039/c7cp02920a], originally designed to study the conformational features of saccharides, in order to check whether it can be extended to the case of tautomeric/epimeric equilibria of monosaccharides...
January 11, 2019: Carbohydrate Research
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...
January 11, 2019: Carbohydrate Research
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...
January 11, 2019: Carbohydrate Research
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...
January 8, 2019: Carbohydrate Research
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 lipooligosaccharide (LOS) fraction produced by Rhodobacter azotoformans that shows production of IL-8, but has an inverse correlation with IL-6 production...
January 7, 2019: Carbohydrate Research
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)...
January 7, 2019: Carbohydrate Research
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.
January 4, 2019: Carbohydrate Research
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...
December 30, 2018: Carbohydrate Research
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)...
December 29, 2018: Carbohydrate Research
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...
December 25, 2018: Carbohydrate Research
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...
December 24, 2018: Carbohydrate Research
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 CH2 OH group significantly...
December 22, 2018: Carbohydrate Research
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