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Complex Oligosaccharides (complex + oligosaccharide)
Selected AbstractsGlycerol and Glycerol Glycol GlycodendrimersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2003Mike M. K. Boysen Abstract Non-covalent interactions between structural parts of complex oligosaccharides and saccharide-recognising proteins are of crucial importance for many cell communication phenomena. Specificity of such interactions and stability of these ligand-receptor complexes are achieved through multivalent interactions between multiple copies of a saccharide ligand and a corresponding number of protein receptors. Substances presenting multiple copies of the saccharide ligand on easily accessible scaffold molecules therefore appear to be promising tools for study of multivalent interactions and their possible inhibition. Such multivalent glycomimetics can be prepared by attachment of saccharide residues to the surface functional groups of dendrimers. In the course of our work, we have prepared novel glycodendrimers with glycerol and glycerol glycol polyether scaffolds. Isopropylidene-protected hydroxyethyl mannoside was chosen as the carbohydrate component, with the construction of the dendritic structures proceeding by a convergent approach featuring iterative Williamson etherification and ozonolysis/hydride reduction steps. Deprotected representatives of such structures are potential inhibitors of mannose-binding lectins of E. coli. Three representative compounds were deprotected and their anti-adhesive properties were examined. The route to these glycodendrimers was also evaluated in terms of synthetic chemistry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Recombinant anti-hCG antibodies retained in the endoplasmic reticulum of transformed plants lack core-xylose and core-,(1,3)-fucose residuesPLANT BIOTECHNOLOGY JOURNAL, Issue 4 2004Rajan Sriraman Summary Plant-based expression systems are attractive for the large-scale production of pharmaceutical proteins. However, glycoproteins require particular attention as inherent differences in the N-glycosylation pathways of plants and mammals result in the production of glycoproteins bearing core-xylose and core-,(1,3)-fucose glyco-epitopes. For treatments requiring large quantities of repeatedly administered glycoproteins, the immunological properties of these non-mammalian glycans are a concern. Recombinant glycoproteins could be retained within the endoplasmic reticulum (ER) to prevent such glycan modifications occurring in the late Golgi compartment. Therefore, we analysed cPIPP, a mouse/human chimeric IgG1 antibody binding to the ,-subunit of human chorionic gonadotropin (hCG), fused to a C-terminal KDEL sequence, to investigate the efficiency of ER retrieval and the consequences in terms of N-glycosylation. The KDEL-tagged cPIPP antibody was expressed in transgenic tobacco plants or Agrobacterium -infiltrated tobacco and winter cherry leaves. N-Glycan analysis showed that the resulting plantibodies contained only high-mannose (Man)-type Man-6 to Man-9 oligosaccharides. In contrast, the cPIPP antibody lacking the KDEL sequence was found to carry complex N-glycans containing core-xylose and core-,(1,3)-fucose, thereby demonstrating the secretion competence of the antibody. Furthermore, fusion of KDEL to the diabody derivative of PIPP, which contains an N-glycosylation site within the heavy chain variable domain, also resulted in a molecule lacking complex glycans. The complete absence of xylose and fucose residues clearly shows that the KDEL-mediated ER retrieval of cPIPP or its diabody derivative is efficient in preventing the formation of non-mammalian complex oligosaccharides. [source] Structural analysis of oligosaccharides by atmospheric pressure matrix-assisted laser desorption/ionisation quadrupole ion trap mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2002Colin S. Creaser An ion source incorporating a fibre optic interface has been constructed for atmospheric pressure matrix-assisted laser desorption/ionisation quadrupole ion trap mass spectrometry. The configuration has been applied to the study of linear and complex oligosaccharides. Multi-stage tandem mass spectrometry (MSn, n,=,2,4) experiments carried out in the ion trap enable extended fragmentation pathways to be investigated that yield structural information. Collisional activation of sodiated oligosaccharides, as demonstrated on the model compound maltoheptaose, produces primarily B and Y fragments resulting from cleavage of glycosidic bonds; fragments from cross-ring cleavages are also observed following further stages of tandem mass spectrometry, providing additional linkage information. The analyses of mixtures of complex oligosaccharides are demonstrated for N-linked glycans from chicken egg glycoproteins and a ribonuclease glycan mixture. Mass spectrometric and tandem mass spectrometric data for sugars with molecular weights up to 4000,Da is shown for mixtures of linear dextrans and N-linked glycans. The use of MSn (n,=,3,,4) on these complex molecules enabled structural information to be elucidated that confirms data observed in the MS/MS spectra. Copyright © 2001 John Wiley & Sons, Ltd. [source] Modular Solid-Phase Synthetic Approach To Optimize Structural and Electronic Properties of Oligoboronic Acid Receptors and Sensors for the Aqueous Recognition of OligosaccharidesCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2004Duane Stones Dr. Abstract This article describes the design and optimization of the first entirely modular, parallel solid-phase synthetic approach for the generation of well-defined polyamine oligoboronic acid receptors and fluorescence sensors for complex oligosaccharides. The synthetic approach allows an effective building of the receptor polyamine backbone, followed by the controlled diversification of the amine benzylic side chains. This approach enabled the testing, in a modular fashion, of the effect of different arylboronic acid units substituted with unencumbering para electron-withdrawing or electron-donating groups. The feasibility of this approach toward automated synthesis was also investigated with the assembly of a sublibrary of receptors by means of the Irori MiniKan technology. Several sublibraries of anthracene-capped sensors containing two or three arylboronic acids were synthesized, and their binding to a series of model disaccharides was examined in neutral aqueous media. The calculation of association constants by fluorescence titrations confirmed that subtle changes in the structures of the interamine spacers in the polyamine backbone can have a significant effect on the stability of the resulting complexes. Most importantly, this study led to the determination of the preferred electronic characteristics for the arylboronate units, and suggests that a new generation of receptors containing very electron-poor arylboronic acids could lead to a significant improvement of binding affinities. [source] | ||||||||||