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Carbohydrate Research

Olesya I Naumenko, Han Zheng, Jianping Wang, Sof'ya N Senchenkova, Hong Wang, Alexander S Shashkov, Alexander O Chizhov, Qun Li, Yuriy A Knirel, Yanwen Xiong
The O-specific polysaccharide (O-antigen) was obtained by mild acid degradation of the lipopolysaccharide of Escherichia albertii O5 (strain T150248) and studied by sugar analysis, selective cleavages of glycosidic linkages, and 1D and 2D 1H and 13C NMR spectroscopy. Partial solvolysis with anh (anhydrous) CF3CO2H and hydrolysis with 0.05 M CF3CO2H cleaved predominantly the glycosidic linkage of β-GalpNAc or β-Galf, respectively, whereas the linkages of α-GlcpNAc and β-Galp were stable. Mixtures of the corresponding tri- and tetra-saccharides thus obtained were studied by NMR spectroscopy and high-resolution ESI MS...
January 3, 2018: Carbohydrate Research
Evelina L Zdorovenko, Alexander S Shashkov, Alexandra A Kadykova, Elena P Kiseleva, Victoria V Savich, Galina I Novik, Yuriy A Knirel
Two specific polysaccharides, together with an →4)-α-d-Glcp-(1→ glucan (bacterial glycogen), were obtained from a lipopolysaccharide preparation isolated from the bacterium Pseudomonas putida BIM B-1100 by phenol/water extraction. The following structures of the polysaccharides were established by composition analysis, Smith degradation, ESI-MS, and 1D and 2D NMR spectroscopy.
December 25, 2017: Carbohydrate Research
Meng Wang, Xiao-Yang Zhang, Rui-Rui Guo, Zhi-Peng Cai, Xiao-Chun Hu, Huan Chen, Shuang Wei, Josef Voglmeir, Li Liu
Two genes encoding the β-N-acetylhexosaminidases Am2301 and Am2446 were cloned successfully from the mucin-degrading bacterium Akkermansia muciniphila. The recombinant enzymes with molecular masses of 61 kDa and 78 kDa were isolated and biochemically characterised. The optimum temperature of both enzymes was 37 °C, and the optimum pH was determined to be pH 5.0 for Am2301 and pH 6.5 for Am2446. The addition of sodium dodecyl sulphate (SDS) reduced the enzymes' activity significantly. Cu2+-ions decreased the activity of Am2301 by 70%, while the activity of Am2446 was significantly reduced by Fe3+-ions...
December 23, 2017: Carbohydrate Research
Yuji Yamazaki, Shunsaku Kimura, Masashi Ohmae
The reaction specificity of the transglycosylation catalyzed by keratanase II from Bacillus circulans KsT202 (KSase II) was studied by using the oxazoline derivatives having keratan sulfate repeating units. The addition of 10% organic cosolvent reduced the activity for the enzymatic transglycosylation. The oxazoline derivative of 6-O-sulfonato-N-acetyllactosamine (su-LacNAc) was processively oligomerized to the corresponding hexamer or longer by the enzyme. This result strongly implies that the enzyme has the large positively numbered subsites...
December 15, 2017: Carbohydrate Research
Jie Shao, Mo Zhu, Ligang Gao, Hua Chen, Xiaoliu Li
Azasugar aldehydes 6a and 6b containing azido groups were prepared from D-mannose. Three novel tetracyclic azasugars fused benzo[e][1,3]thiazin-4-one 9a-1, 9a-2 and 9a-3 were conveniently synthesized from 6a by the tandem intramolecular Staudinger/aza-Wittig/cyclization reaction under microwave radiation. Two unexpected elimination compounds 8b-1 and 8b-2 were achieved as the main products from 6b in the same processes. The newly synthesized azasugars were examined for their HIV reverse transcriptase (RT) inhibitory activities...
December 15, 2017: Carbohydrate Research
Jenn-Jong Young, Kuang-Ming Cheng, Yen-An Young, Xin-An Chen, Yu-Hao Chen, Tein-Yao Chang, Hui-Ju Yen, Cheng-Cheung Chen
Herein, we describe an improved procedure for the green synthesis of chondroitin sulfate stabilized silver nanoparticles (ChS-AgNPs). Glucose was used as a reducing agent under alkaline conditions to obtain a small particle size (<10 nm), and the reduction was complete within one hour at room temperature. The concentration of NaOH affected the reaction rate, formation yield, and particle size of ChS-AgNPs. The formation of AgNPs was confirmed using UV-vis, TEM, XRD, and XPS. ChS-AgNPs showed excellent catalytic activities in the reduction of 4-nitrophenol by NaBH4, and the reaction rate increased linearly with increasing catalyst amounts...
December 14, 2017: Carbohydrate Research
Shinya Hanashima, Akitsugu Suga, Yoshiki Yamaguchi
Bisected N-glycans play significant roles in tumor migration and Alzheimer's disease through modulating the action and localization of their carrier proteins. Such biological functions are often discussed in terms of the conformation of the attached N-glycans with or without bisecting GlcNAc. To obtain insights into the effects of bisecting GlcNAc on glycan conformation, a systematic NMR structural analysis was performed on two pairs of synthetic N-glycans, with and without bisecting GlcNAc. The analysis reveals that terminal GlcNAcs and bisecting GlcNAc cooperate to restrict the conformations of both the α1-3 and α1-6 branches of N-glycans...
December 14, 2017: Carbohydrate Research
Bettina Riedl, Walther Schmid
Ulosonic acids are an important class of carbohydrates, including well-known representatives as 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo), 3-deoxy-d-glycero-d-galacto-non-2-ulosonic acid (Kdn) and N-Acetylneuraminic acid (Neu5Ac). As part of the lipopolysaccharides (LPS) and capsular polysaccharides (CPS, K-antigen), these carbohydrates can be found on the surfaces of, both, Gram-positive and Gram-negative bacteria. We developed a synthetic approach to access tetrazole-derivatives of these compounds. Tetrazoles have shown to be ideal analogues for the bioisosteric replacement of carboxylic acids in several drugs, improving biological activity and pharmacokinetic properties...
December 14, 2017: Carbohydrate Research
Maria V Panova, Nikita M Podvalnyy, Eugene L Okun, Polina I Abronina, Alexander O Chizhov, Leonid O Kononov
Selectively protected mono-, di- and trisaccharide thioglycoside building blocks with unprotected primary hydroxy group at the non-reducing end, available in only one step from 3-O-benzoyl β-d-arabinofuranose 1,2,5-orthobenzoate, were used in the synthesis of linear α(1 → 5)-linked oligoarabinofuranosides up to octasaccharide. The obtained oligosaccharides contain 4-(2-chloroethoxy)phenyl (CEP) or 4-(2-azidoethoxy)phenyl (AEP) pre-spacer aglycons that allow preparation of neoglycoconjugates.
December 8, 2017: Carbohydrate Research
Eleonora Altman, Vandana Chandan, Blair A Harrison, Evgeny Vinogradov
Structural characterization of the lipopolysaccharide (LPS) from a nontypeable Helicobacter pylori strain PJ1 and two corresponding mutants, PJ1 HP1283:cam and PJ1 HP1284:cam, was performed using a combination of NMR and mass spectrometric techniques. It resulted in the core structure that differed significantly from the one proposed previously. Overall architecture of PJ1 LPS was found to be consistent with a structural model described for several other H. pylori strains. It contained a polymer of d-glycero-d-manno-heptose (dd-Hep) as the O-chain component, linked to α-1,6-glucan through a dd-Hep oligosaccharide...
December 7, 2017: Carbohydrate Research
Nadezhda E Ustyuzhanina, Maria I Bilan, Andrey S Dmitrenok, Elizaveta Yu Borodina, Nikolay E Nifantiev, Anatolii I Usov
A highly regular fucan sulfate SHFS was isolated from the sea cucumber Stichopus horrens by extraction of the body walls in the presence of papain followed by ion-exchange and gel permeation chromatography. SHFS had MW of about 140 kDa and contained fucose and sulfate in the molar ratio of about 1:1. Chemical and NMR spectroscopic methods were applied for the structural characterization of the polysaccharide. SHFS was shown to have linear molecules built up of 3-linked α-l-fucopyranose 2-sulfate residues...
December 7, 2017: Carbohydrate Research
Andrei V Perepelov, Tingting Chen, Sofya N Senchenkova, Andrei V Filatov, Jingjie Song, Alexander S Shashkov, Bin Liu, Yuriy A Knirel
The O-specific polysaccharide (O-antigen) is a part of the lipopolysaccharide on the cell surface of Gram-negative bacteria. The O-polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide of Escherichia coli O27 and studied by sugar analysis and Smith degradation along with 1H and 13C NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established, which is unique among known structures of bacterial polysaccharides:where GlcA is non-stoichiometrically O-acetylated at position 3 (∼22%) or 4 (∼37%)...
December 2, 2017: Carbohydrate Research
Rui Wang, Ji-Zong Chen, Xiu-An Zheng, Rui Kong, Shan-Shan Gong, Qi Sun
An efficient method for selective anomeric deacetylation of peracetylated mono-, di-, and trisaccharides has been developed by using 2 mol% Hf(OTf)4 as catalyst in acetonitrile. Employment of ultrasonic irradiation could significantly accelerate the reaction rate. Mechanistic study confirmed the hydrolysis nature of this reaction, and NMR experimental data suggested that multiple peracetylated saccharide molecules may ligate to Hf(IV) cation primarily via the anomeric acetate to promote its specific hydrolysis...
December 2, 2017: Carbohydrate Research
Felipe Vilches, María Cristina Ravanal, Felipe Bravo-Moraga, Danilo Gonzalez-Nilo, Jaime Eyzaguirre
Penicillium purpurogenum secretes numerous lignocellulose-degrading enzymes, including four arabinofuranosidases and an exo-arabinanase. In this work, the biochemical properties of an endo-arabinanase (ABN1) are presented. A gene, coding for a potential ABN was mined from the genome. It includes three introns. The cDNA is 975 bp long and codes for a mature protein of 324 residues. The cDNA was expressed in Pichia pastoris. The enzyme is active on debranched arabinan and arabinooligosaccharides. In contrast to other characterized ABNs, inactive on p-nitrophenyl-α-L-arabinofuranoside (pNPAra), ABN1 is active on this substrate...
November 26, 2017: Carbohydrate Research
Michael Almond, Mustapha G Suleiman, Matthew Hawkins, Daniel Winder, Thomas Robshaw, Megan Waddoups, Paul N Humphreys, Andrew P Laws
Alpha and beta-glucoisosaccharinic acids ((2S,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid and (2R,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid) which are produced when cellulosic materials are treated with aqueous alkali are potentially valuable platform chemicals. Their highly functionalised carbon skeleton, with fixed chirality at C-2 and C-4, makes them ideal starting materials for use in synthesis. In order to assess the potential of these saccharinic acids as platform chemicals we have explored the protecting group chemistry of the lactone form of alpha-glucoisosaccharinic acid (α-GISAL)...
November 26, 2017: Carbohydrate Research
Yiren Xu, Guanghui Zong, Shuhui Jin, Jianjun Zhang
Aeromonas bestiarum 207 is a bacterial pathogen with severe impact on aquaculture. In a recent study, the structure of OPS antigens from Aeromonas bestiarum was identified as pentasaccharide repeating units. Synthesis of the pentasaccharide repeating unit and its derivative are reported. Stereo- and regio-specific synthesis was achieved under Schmidt glycosylation conditions employing appropriately protected L-rhamopyranosyl and D-glucopyranosylamine building blocks. The pentasaccharide synthesis was achieved using a [3 + 2] strategy with an overall yield of 5...
November 21, 2017: Carbohydrate Research
Mads Heuckendorff, Henrik H Jensen
We have explored the possibility of using 1,3-diiodo-5,5-dimethylhydantoin (DIDMH) as an alternative to N-iodosuccinimide (NIS) for activation of glycosyl donors of the thioglycoside type in various glycosylation reactions. DIDMH was found to match NIS when it comes to the capability to activate thioglycosides and provide glycosylation products in good yields. Notably, with the two equivalents of reactive iodonium ions per molecule of DIDMH less mass needs to be added making this activator a more atom economically alternative to NIS...
November 21, 2017: Carbohydrate Research
Karina Panczyk, Wojciech Plazinski
Conformation of monosaccharides, including the ring shape, has for years been the subject of intensive research. Although d-aldohexopyranoses are the most extensively studied pyranoses, there also exist other groups of saccharides that contain analogous chemical system of the six-membered ring. Here we describe in details the results of the molecular dynamics-based conformational analysis concerning a series of pyranoses, namely: d-aldopentoses, d-ketohexoses as well as deoxy- (d-quinovose, l-fucose, l-rhamnose) and dideoxy- (abequose, paratose, tyvelose, digitoxose) derivatives of aldohexoses...
November 21, 2017: Carbohydrate Research
Quan V Vo, Simone Rochfort, Pham C Nam, Tuan L Nguyen, Trung T Nguyen, Adam Mechler
Aromatic and indole glucosinolates are important members of the glucosinolate family of compounds du to their potential medicinal properties. They are known to exert antioxidant and anti-carcinogenic activity either by the natural products themselves, or their metabolic products including indole-3-carbinol and isothiocyanates. Natural glucosinolates are all β-glucosinolates; however, α-glucosinolates are also promising compounds for medicinal applications and hence have to be produced synthetically for any bio-activity studies...
November 20, 2017: Carbohydrate Research
Lihua Du, Zhipeng Jiang, Liangliang Xu, Nani Zhou, Jiahong Shen, Zhen Dong, Le Shen, Hong Wang, Xiping Luo
Lipase-catalyzed regioselective synthesis of neohesperidin ester derivatives was performed by Lipase TL IM from Thermomyces lanuginosus in a continuous-flow microreactor and then their antimicrobial activity was studied. It appears that neohesperidin, neohesperidin dihydrochalcone with primary OH on the sugar part is the most reactive substrate. Various reaction parameters were investigated including substrate molar ratio, reaction time and temperature. Maximum conversion (92%) was obtained under the optimal condition of substrate molar ratio of 8:1 (vinyl esters: neohesperidin) at 52 °C for about 35 min...
November 18, 2017: Carbohydrate Research
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