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Carbohydrate Research

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https://www.readbyqxmd.com/read/28214389/synthesis-of-lacto-n-tetraose
#1
Kelly M Craft, Steven D Townsend
Human milk oligosaccharides (HMOs) are the third largest macromolecular component of breast milk and offer infants numerous health benefits, most of which stem from the development of a healthy microbiome. Characterization, quantification, and chemical derivatization of HMOs remains a frontier issue in glycobiology due to the challenge of isolating appreciable quantities of homogenous HMOs from breast milk. Herein, we report the synthesis of the human milk tetrasaccharide lacto-N-tetraose (LNT). LNT is ubiquitous in human breast milk as it is a core structure common to longer-chain HMOs and many glycolipids...
February 11, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28231561/structural-analysis-of-rebaudioside-a-derivatives-obtained-by-lactobacillus-reuteri-180-glucansucrase-catalyzed-trans-%C3%AE-glucosylation
#2
Gerrit J Gerwig, Evelien M Te Poele, Lubbert Dijkhuizen, Johannis P Kamerling
The wild-type Gtf180-ΔN glucansucrase enzyme from Lactobacillus reuteri 180 was found to catalyze the α-glucosylation of the steviol glycoside rebaudioside A, using sucrose as glucosyl donor in a transglucosylation process. Structural analysis of the formed products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that rebaudioside A is specifically α-d-glucosylated at the steviol C-19 β-d-glucosyl moiety (55% conversion). The main product is a mono-(α1 → 6)-glucosylated derivative (RebA-G1)...
January 31, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28199859/structure-of-the-lps-o-chain-from-fusobacterium-nucleatum-strain-10953-containing-sialic-acid
#3
Evgeny Vinogradov, Frank St Michael, Kiyonobu Homma, Ashu Sharma, Andrew D Cox
Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about virulence factors of this organism and thus we have initiated studies to examine the bacterial surface glycochemistry. Consistent with a recent paper suggesting that F. nucleatum strain 10593 can synthesize sialic acid, a staining technique identified sialic acid on the bacterial surface...
January 28, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28192685/4-hydroxybenzaldehyde-chitooligomers-suppresses-h2o2-induced-oxidative-damage-in-microglia-bv-2%C3%A2-cells
#4
Sea-Hun Oh, BoMi Ryu, Dai-Hung Ngo, Won-Suk Kim, Dong Gyu Kim, Se-Kwon Kim
Positive charges of chitooligomer (COS) enable COS to interact with negatively charged anionic groups on the cell surface resulting in an improvement in the biological activity of COS and its derivatives. In this study, 4-hydroxybenzaldehyde-COS (HB-COS) was synthesized and investigated for its abilities against H2O2-induced oxidative stress in microglia BV-2 cells. Under oxidative stress, HB-COS significantly attenuated reactive oxygen species (ROS) generation and DNA oxidation, and upregulated the protein levels of antioxidative enzymes...
January 16, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28135569/c-5a-substituted-validamine-type-glycosidase-inhibitors
#5
Michael Schalli, Andreas Wolfsgruber, Andres Gonzalez Santana, Christina Tysoe, Roland Fischer, Arnold E Stütz, Martin Thonhofer, Stephen G Withers
A series of N-alkyl derivatives of the D-galactosidase inhibitor 1,4-di-epi-validamine featuring lipophilic substituents at position C-5a was prepared and screened for their glycosidase inhibitory properties. Products turned out selective for β-galactosidases as well as β-glucosidases.
January 13, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28167367/large-scale-synthesis-and-regioselective-protection-schemes-of-ethyl-2-azido-2-deoxy-1-thio-%C3%AE-d-cellobioside-for-preparation-of-heparin-thiodisaccharide-building-blocks
#6
Kevin Sheerin, Lorenzo Guazzelli, Stefan Oscarson
Crystalline acetylated ethyl 2-azido-2-deoxy-1-thio-α-d-cellobioside has been prepared on a multigram scale from cellobiose in an overall yield of 23% with no chromatography required and converted after deacetylation into the 4',6'-O-benzylidene and 4',6'-O-benzylidene-6-O-TBDMS protected derivatives. Applying a number of regioselective benzylation methods on these gave access to a variety of regioselectively protected derivatives, both mono-ols (2'- and 3-OH), diols (2',6-, 2',3-, and 3,6-di-OH), and triols (2',3,6- and 2',3',3-tri-OH)...
January 11, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28135570/the-structure-of-the-lps-o-chain-of-fusobacterium-nucleatum-strain-25586-containing-two-novel-monosaccharides-2-acetamido-2-6-dideoxy-l-altrose-and-a-5-acetimidoylamino-3-5-9-trideoxy-gluco-non-2-ulosonic-acid
#7
Evgeny Vinogradov, Frank St Michael, Andrew D Cox
Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about the virulence factors of this organism, and thus we have initiated studies to examine the bacterium's surface glycochemistry. We isolated lipopolysaccharide (LPS) from F. nucleatum strain 25586 and purified and performed structural analysis on the O-antigen polysaccharide...
January 9, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28110079/isomelezitose-formation-by-glucansucrases
#8
Gregory L Côté, Christopher D Skory
Several glucansucrases were surveyed for their ability to produce isomelezitose, a trisaccharide with the structure α-D-glucopyranosyl (1 → 6) β-D-fructofuranosyl (2 ↔ 1) α-D-glucopyranoside. Nearly all strains tested, with one exception, produced at least trace levels of isomelezitose. Yields were low but significant, ranging from less than 1% to approximately 5% based on sucrose. This trisaccharide may arise in either of two ways: glucopyranosyl transfer to the 6(Fru)-OH position of sucrose, or to the anomeric OH position of isomaltulose...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28107657/removal-of-some-common-glycosylation-by-products-during-reaction-work-up
#9
Mads Heuckendorff, Henrik H Jensen
With the aim of improving the general glycosylation protocol to facilitate easy product isolation it was shown that amide by-products from glycosylation with trichloroacetimidate and N-phenyl trifluoroacetimidate donors could be removed during reaction work-up by washing with a basic aqueous solution. Excess glycosyl acceptor or lactol originating from glycosyl donor hydrolysis could equally be removed from the reaction mixture by derivatization with a basic tag and washing with an acidic solution during reaction work-up...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28107656/synthesis-of-an-allergy-inducing-tetrasaccharide-4p-x
#10
Takashi Moriya, Naoki Nagahata, Rei Odaka, Hirohide Nakamura, Jun Yoshikawa, Katsumi Kurashima, Tadao Saito
4P-X (β-D-galactopyranosyl-(1 → 4)-β-D-galactopyranosyl-(1 → 6)-[β-D-galactopyranosyl-(1 → 4)]-β-D-glucopyranose) is included in galacto-oligosaccharides (GOSs) produced by β-galactosidase derived from Bacillus circulans. 4P-X has been known to induce particularly strong allergies. High purity 4P-X is essential for use as a standard to quantify the amount of 4P-X in GOSs; however, the isolation of high purity 4P-X has never been reported. In this study, we achieved the synthesis of 4P-X by a combination of organic and enzymatic chemical syntheses in a short time...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28107655/discrimination-between-naphthacene-and-triphenylene-using-cellulose-tris-4-methylbenzoate-and-cellulose-tribenzoate-a-computational-study
#11
Yusuke Murakami, Tohru Shibata, Kazuyoshi Ueda
The mechanisms of naphthacene and triphenylene discrimination using commercially available cellulose tris(4-methylbenzoate) (CMB) and cellulose tribenzoate (CB) chiral stationary phases were investigated using molecular mechanics calculations. Naphthacene and triphenylene could be separated by liquid chromatography on CMB and CB, with triphenylene being eluted earlier than naphthacene on both phases. However, the corresponding separation factor is much larger for CMB than for CB. The docking of these polycyclic aromatic hydrocarbons to the above polymers suggested that the most important sites of CMB and CB for interacting with these hydrocarbons are located at equivalent positions, featuring a space surrounded by main chain glucose units and benzoyl side chains...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28088676/structure-of-o-specific-polysaccharide-of-oligotropha-carboxidovorans-om5-a-wastewater-bacterium
#12
Iwona Komaniecka, Adam Choma, Katarzyna Zamlynska, Anna Sroka-Bartnicka, Pawel Sowinski
Oligotropha carboxidovorans strain OM5 (previously known as Pseudomonas carboxydovorans OM5) is a rod-shaped Gram-negative bacterium isolated from wastewater. This bacterium is able to live in aerobic and, facultatively, in autotrophic conditions. For autotrophic growth, the bacteria can utilize carbon monoxide or hydrogen as a source of energy. The O-specific polysaccharide isolated from O. carboxidovorans OM5 lipopolysaccharide was structurally characterized using chemical analyses, 1D and 2D NMR spectroscopy, and MALDI-TOF mass spectrometry techniques...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28088128/structure-of-the-o-specific-polysaccharide-from-the-lipopolysaccharide-of-aeromonas-hydrophila-strain-k691-containing-4-acetamido-4-6-dideoxy-d-glucose
#13
Katarzyna Pakiet, Anna Turska-Szewczuk, Magdalena A Karas, Agnieszka Pekala, Hubert Pietras
The O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Aeromonas hydrophila strain K691 and studied by chemical methods and (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, NOESY, (1)H-detected heteronuclear (1)H,(13)C HSQC, and HMBC experiments. It was found that the O-specific polysaccharide was built up of pentasaccharide repeating units composed of β-GlcpNAc, 2-O-acetylated α-Rhap, and β-Quip4NAc residues. The following structure of the OPS was established: →3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→3)-α-l-Rha2OAc-(1→3)-β-d-GlcNAc-(1→2)-β-d-Qui4NAc-(1→...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28064042/influence-of-aglycone-structures-on-n-glycan-processing-reactions-in-the-endoplasmic-reticulum
#14
Kiichiro Totani, Kenta Yamaya, Makoto Hirano, Yukishige Ito
Glycoprotein N-linked oligosaccharides in the endoplasmic reticulum function as tags to regulate glycoprotein folding, sorting, secretion and degradation. Since the N-glycan structure of a glycoprotein should reflect the folding state, N-glycan processing may be affected by the aglycone state. In this study, we examined the influence of aglycone structures on N-glycan processing using synthetic substrates. We prepared (Glc1)Man9GlcNAc2 linked to hydrophobic BODIPY-dye with a systematic series of different linker lengths...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28033491/evaluation-of-carbohydrate-cysteamine-thiazolidines-as-pro-drugs-for-the-treatment-of-cystinosis
#15
Yasaman Ramazani, Elena N Levtchenko, Lambertus Van Den Heuvel, Ann Van Schepdael, Prasanta Paul, Ekaterina A Ivanova, Anna Pastore, Trina M Hartman, Neil P J Price
Cystinosis is a genetic disorder caused by malfunction of cystinosin and is characterized by accumulation of cystine. Cysteamine, the medication used in cystinosis, causes halitosis resulting in poor patient compliance. Halitosis is mainly caused by the formation of dimethylsulfide as the final product in the cysteamine metabolism pathway. We have synthesized carbohydrate-cysteamine thiazolidines, and hypothesized that the hydrolytic breakdown of cysteamine-thiazolidines can result in free cysteamine being released in target organs...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28011438/photoswitchable-carbohydrate-based-fluorosurfactants-as-tuneable-ice-recrystallization-inhibitors
#16
Madeleine K Adam, Yingxue Hu, Jessica S Poisson, Matthew J Pottage, Robert N Ben, Brendan L Wilkinson
Cryopreservation is an important technique employed for the storage and preservation of biological tissues and cells. The limited effectiveness and significant toxicity of conventionally-used cryoprotectants, such as DMSO, have prompted efforts toward the rational design of less toxic alternatives, including carbohydrate-based surfactants. In this paper, we report the modular synthesis and ice recrystallization inhibition (IRI) activity of a library of variably substituted, carbohydrate-based fluorosurfactants...
February 1, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28027727/new-investigators-in-glycoscience
#17
Rob Field
No abstract text is available yet for this article.
January 13, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/27987423/investigating-the-relationship-between-temperature-conformation-and-calcium-binding-in-heparin-model-oligosaccharides
#18
Ashley Hughes, Maria Meneghetti, Teng-Yi Huang, Shang-Cheng Hung, Stefano Elli, Marco Guerrini, Timothy Rudd, Marcelo Lima, Edwin Yates
Glycosaminoglycans such as heparan sulfate (HS) are major components of the cell surface and extracellular matrix (ECM) of all multicellular animals, connecting cells to each other as well as to their environment. The ECM must, therefore, both sense and accommodate changes to external conditions. Heparin, a model compound for HS, responds to increased temperatures, involving changes in the populations of conformational states with implications for the binding of HS to proteins, cations and, potentially, for its activity...
January 13, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/27984704/synthesis-of-aza-crown-analogues-and-macrocyclic-bis-lactams-with-sucrose-scaffold
#19
Michał Kowalski, Sławomir Jarosz
2,3,3',4,4'-Penta-O-benzylsucrose was converted into the corresponding diaminoalcohol which was used as a key building block in the synthesis of the analogues of aza-crown ethers and bis-lactams.
January 13, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/27960098/enzymatic-synthesis-of-human-blood-group-p1-pentasaccharide-antigen
#20
Dawa Tsering, Congcong Chen, Jinfeng Ye, Zhipeng Han, Bai-Qian Jing, Xian-Wei Liu, Xi Chen, Fengshan Wang, Peixue Ling, Hongzhi Cao
The enzymatic synthesis of biologically important and structurally unique human P1PK blood group type P1 pentasaccharide antigen is described. This synthesis features a three-step sequential one-pot multienzyme (OPME) glycosylation for the stepwise enzymatic chain elongation of readily available lactoside acceptor with cheap and commercially available galactose and N-acetylglucosamine as donor precursors. This enzymatic synthesis provides an operationally simple approach to access P1 pentasaccharide and its structurally related Gb3 and P1 trisaccharide epitopes...
January 13, 2017: Carbohydrate Research
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