| 41. |
- Forsman, Huamei, et al.
(författare)
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The beta-galactoside binding immunomodulatory lectin galectin-3 reverses the desensitized state induced in neutrophils by the chemotactic peptide f-Met-Leu-Phe: role of reactive oxygen species generated by the NADPH-oxidase and inactivation of the agonist
- 2008
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 18:11, s. 905-12
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils interacting with a chemoattractant gradually become nonresponsive to further stimulation by the same agonist, a process known as desensitization. Receptor desensitization is a highly regulated process that involves different mechanisms depending on which receptor-ligand pair that is studied. Galectin-3, a member of a large family of beta-galactoside-binding lectins, has been suggested to be a regulator of the inflammatory process, augmenting or directly triggering the neutrophil functional repertoire. We show here that the desensitized state of neutrophils interacting with the chemotactic peptide fMLF is broken by galectin-3 and that this is achieved through an oxygen radical-mediated inactivation of the chemoattractant. The effect was inhibited by the competitor lactose and required the affinity of galectin-3 for N-acetyllactosamine, a saccharide typically found on cell surface glycoproteins. The latter was shown using a galectin-3 mutant that lacked N-acetyllactosamine binding activity, and this protein was not active. The mechanism behind the inactivation of the chemoattractant was found to depend on the ability of galectin-3 to induce a neutrophil generation/secretion of reactive oxygen species which in combined action with myeloperoxidase inactivated the peptides.
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| 42. |
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| 43. |
- Furevi, Axel, 1992-, et al.
(författare)
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Elucidation of the O-antigen structure of Escherichia coli O93 and characterization of its biosynthetic genes
- 2023
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 33:4, s. 289-300
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the O-antigen from the international reference strain Escherichia coli O93:-:H16 has been determined. A nonrandom modal chain-length distribution was observed for the lipopolysaccharide, a pattern which is typical when long O-specific polysaccharides are expressed. By a combination of (i) bioinformatics information on the gene cluster related to O-antigen synthesis including putative function on glycosyl transferases, (ii) the magnitude of NMR coupling constants of anomeric protons, and (iii) unassigned 2D H-1, C-13-HSQC, and H-1,H-1-TOCSY NMR spectra it was possible to efficiently elucidate the structure of the carbohydrate polymer in an automated fashion using the computer program CASPER. The polysaccharide also carries O-acetyl groups and their locations were determined by 2D NMR experiments showing that similar to 1/2 of the population was 2,6-di-O-acetylated, similar to 1/4 was 2-O-acetylated, whereas similar to 1/4 did not carry O-acetyl group(s) in the 3-O-substituted mannosyl residue of the repeating unit. The structure of the tetrasaccharide repeating unit of the O-antigen is given by: -> 2)-beta-D-Manp-(1 -> 3)-beta-D-Manp2Ac6Ac-(1 -> 4)-beta-D-GlcpA-(1 -> 3)-alpha-D-GlcpNAc-(1 ->, which should also be the biological repeating unit and it shares structural elements with capsular polysaccharides from E. coli K84 and K50. The structure of the acidic O-specific polysaccharide from Cellulophaga baltica strain NN015840(T) differs to that of the O-antigen from E. coli O93 by lacking the O-acetyl group at O6 of the O-acetylated mannosyl residue.
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| 44. |
- Furevi, Axel, 1992-, et al.
(författare)
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Structural elucidation of the O-antigen polysaccharide from Escherichia coli O125ac and biosynthetic aspects thereof
- 2022
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 32:12, s. 1089-1100
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Tidskriftsartikel (refereegranskat)abstract
- Enteropathogenic Escherichia coli O125, the cause of infectious diarrheal disease, is comprised of two serogroups, viz., O125ab and O125ac, which display the aggregative adherence pattern with epithelial cells. Herein, the structure of the O-antigen polysaccharide from E. coli O125ac:H6 has been elucidated. Sugar analysis revealed the presence of fucose, mannose, galactose and N-acetyl-galactosamine as major components. Unassigned 1H and 13C NMR data from one- and two-dimensional NMR experiments of the O125ac O-antigen in conjunction with sugar components were used as input to the CASPER program, which can determine polysaccharide structure in a fully automated way, and resulted in the following branched pentasaccharide structure of the repeating unit: →4)[β-D-Galp-(1 → 3)]-β-D-GalpNAc-(1 → 2)-α-D-Manp-(1 → 3)-α-L-Fucp-(1 → 3)-α-D-GalpNAc-(1→, where the side chain is denoted by square brackets. The proposed O-antigen structure was confirmed by 1H and 13C NMR chemical shift assignments and determination of interresidue connectivities. Based on this structure, that of the O125ab O-antigen, which consists of hexasaccharide repeating units with an additional glucosyl group, was possible to establish in a semi-automated fashion by CASPER. The putative existence of gnu and gne in the gene clusters of the O125 serogroups is manifested by N-acetyl-D-galactosamine residues as the initial sugar residue of the biological repeating unit as well as within the repeating unit. The close similarity between O-antigen structures is consistent with the presence of two subgroups in the E. coli O125 serogroup.
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| 45. |
- Gao, Ya, et al.
(författare)
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Preferred conformations of lipooligosaccharides and oligosaccharides of Moraxella catarrhalis
- 2020
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 30:2, s. 86-94
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella catarrhalis (M. catarrhalis) is a pathogenic gram-negative bacterium that causes otitis media and sinusitis in children. Three major serotypes A, B and C are identified to account for approximately 95% of the clinical isolates. Understanding the conformational properties of different serotypes of M. catarrhalis provides insights into antigenic determinants. In this work, all-atom molecular dynamics simulations were conducted for M. catarrhalis lipooligosaccharide (LOS) bilayer systems and oligosaccharides (OS) in water solution to investigate the conformational similarities and differences of three serotypes. For up to 10 neutral monosaccharides in the core part, the conformational ensembles described by the pair-wise root mean square deviation distributions are similar among the three serotypes of either the LOS or OS. At the central beta-(1 -> 4)-linkage, anti-psi conformation in conjunction with the gauche-gauche (g(-)) conformation of the central trisubstituted glucosyl residue is observed as the dominant conformation to sustain the structural characteristics of M. catarrhalis three types, which is further supported by calculated transglycosidic (3)J(C,H)(psi(H)) of serotype A in comparison to experimental data. Interestingly, the conformational variability of three serotypes is more restricted for the OS in water solution than that in the LOS bilayer systems. The LOS-LOS interactions in the bilayer systems are responsible for the increased conformational diversity despite of tight packing. Solvent-accessible surface area analysis suggests that a trisaccharide attached to the beta-(1 -> 6)-linked sugar in all three serotypes of LOS could be the common epitope and have the possibility to interact with antibodies.
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| 46. |
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| 47. |
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| 48. |
- Greffe, L., et al.
(författare)
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Synthesis, preliminary characterization, and application of novel surfactants from highly branched xyloglucan oligosaccharides
- 2005
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 15:4, s. 437-445
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Tidskriftsartikel (refereegranskat)abstract
- A novel class of nonionic, carbohydrate-based surfactants has been synthesized from the plant polysaccharide xyloglucan. Enzymatic hydrolysis of xyloglucan yielded a series of well-defined, highly branched oligosaccharides that, following reductive amination, were readily conjugated with fatty acids bearing C-8 to C-18 chains under mild conditions. The critical micelle concentration, determined by tensiometry and dye-inclusion measurements, showed a typical dependence on acyl chain length and was sensitive to the degree of galactosylation of the head group. Several compounds from this new group of surfactants, especially those with C-14 and C-16 chains, were useful for the extraction of membrane-bound enzyme markers from different plant cell compartments in catalytically active form.
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| 49. |
- Gulshan Kazi, Zubaida, et al.
(författare)
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A CGTase with high coupling activity using γ-cyclodextrin isolated from a novel strain clustering under the genus Carboxydocella.
- 2015
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 25:5, s. 514-523
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Tidskriftsartikel (refereegranskat)abstract
- Cyclodextrin glucanotransferases (CGTases; EC 2.4.1.19) have mainly been characterized for their ability to produce cyclodextrins (CDs) from starch in an intramolecular transglycosylation reaction (cyclization). However, this class of enzymes can also catalyze intermolecular transglycosylation via disproportionation or coupling reactions onto a wide array of acceptors and could therefore be valuable as a tool for glycosylation. In this paper, we report the gene isolation, via the CODEHOP-strategy, expression and characterization of a novel CGTase (CspCGT13) from a Carboxydocella sp. This enzyme is the first glycoside hydrolase isolated from the genus, indicating starch degradation via cyclodextrin production in the Carboxydocella strain. The fundamental reactivities of this novel CGTase are characterized and compared to two commercial CGTases, assayed under identical condition, in order to facilitate interpretation of the results. The comparison showed that the enzyme, CspCGT13, displayed high coupling activity using γ-CD as donor, despite preferentially forming α and β-CD in the cyclization reaction using wheat starch as substrate. Comparison of subsite conservation within previously characterized CGTases showed significant sequence variation in subsite -3 and -7, which may be important for the coupling activity.
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| 50. |
- Gunnarsson, Lavinia Cicortas, 1977-, et al.
(författare)
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Engineered xyloglucan specificity in a carbohydrate-binding module
- 2006
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 16:12, s. 1171-1180
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Tidskriftsartikel (refereegranskat)abstract
- The field of plant cell wall biology is constantly growing and consequently so is the need for more sensitive and specific probes for individual wall components. Xyloglucan is a key polysaccharide widely distributed in the plant kingdom in both structural and storage tissues that exist in both fucosylated and non-fucosylated variants. Presently, the only xyloglucan marker available is the monoclonal antibody CCRC-M1 that is specific to terminal alpha-1,2-linked fucosyl residues on xyloglucan oligo- and polysaccharides. As a viable alternative to searches for natural binding proteins or creation of new monoclonal antibodies, an approach to select xyloglucan-specific binding proteins from a combinatorial library of the carbohydrate-binding module, CBM4-2, from xylanase Xyn10A of Rhodothermus marinus is described. Using phage display technology in combination with a chemoenzymatic method to anchor xyloglucan to solid supports, the selection of xyloglucan-binding modules with no detectable residual wild-type xylan and beta-glucan-binding ability was achieved.
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