A detailed study of the periodate oxidation of sialic acids in glycoproteins.
TL;DR: Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids.
Abstract: Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland, respectively, can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids. In contrast, the C-8 compounds can be obtained in a maximum yield of about 40%. Under identical conditions,N-glycoloylneuraminic acid is oxidized about 1.5 times faster than theN-acetylated derivative. After release of the sialic acids by acid hydrolysis, the characterization of the oxidation products was carried out by TLC, by GLC and GLC-MS of the corresponding pertrimethylsilyl derivatives, and by 500-MHz1H-NMR spectroscopy. In addition, molar response factors for GLC analysis and extinction coefficients in the orcinol/Fe3+/HCl assay were determined.
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TL;DR: It is reported here that fast-atom bombardment-mass-spectrometry (FAB-MS) of native sialic acids provides specific detection and quantitation of many previously known compounds and shows that the alkaline conditions traditionally used for analytical de-O-acetylation of sIALic acids causes substantial conversion of 4,8-anhydro-N- acetyl-neuraminic acid in acid hydrolysates of horse serum.
53 citations
TL;DR: The adhesins of Escherichia coli strains HB101 and HB101, which express S fimbriae encoded by a recombinant plasmid containing the sfaI and sfaII gene clusters, were characterized with regard to the detailed structural requirements of their binding to sialyloligosaccharides on (neo)glycoproteins and (neO)glycolipids.
Abstract: The adhesins of Escherichia coli strains HB101(pANN801-13) and HB101(pAZZ50), which express S fimbriae encoded by a recombinant plasmid containing the sfaI and sfaII gene clusters, respectively, were characterized with regard to the detailed structural requirements of their binding to sialyloligosaccharides on (neo)glycoproteins and (neo)glycolipids. From binding and binding inhibition studies in solid-phase enzyme immunoassays with isolated S fimbriae, several major conclusions can be drawn. S fimbriae bind specifically to sialic acid on gangliosides. The most active structural variant of sialic acid on GM3 ganglioside is N-glycolylneuraminic acid (NeuGc). In contrast to previous reports, high binding activities were measured also for b-series gangliosides expressing NeuAc alpha (2-8)NeuAc. In agreement with earlier studies, the site of sialic acid substitution to subterminal sugars strongly influences the binding to sialyloligosaccharides, i.e., alpha-6-linked sialic acid is only poorly recognized by the adhesin compared with alpha-3-linked sialic acid. C-8 and C-9 hydroxyl groups form essential structural elements of sialic acid in the binding event.
44 citations
TL;DR: Novel antibodies that specifically target with high affinity the STn glycan independent of its carrier protein are identified, affording the potential to recognize a wider array of cancer-specific sialylated proteins.
Abstract: Targeted therapeutics that can differentiate between normal and malignant tumor cells represent the ideal standard for the development of a successful anti-cancer strategy. The Sialyl-Thomsen-nouveau antigen (STn or Sialyl-Tn, also known as CD175s) is rarely seen in normal adult tissues, but it is abundantly expressed in many types of human epithelial cancers. We have identified novel antibodies that specifically target with high affinity the STn glycan independent of its carrier protein, affording the potential to recognize a wider array of cancer-specific sialylated proteins. A panel of murine monoclonal anti-STn therapeutic antibodies were generated and their binding specificity and efficacy were characterized in vitro and in in vivo murine cancer models. A subset of these antibodies were conjugated to monomethyl auristatin E (MMAE) to generate antibody-drug conjugates (ADCs). These ADCs demonstrated in vitro efficacy in STn-expressing cell lines and significant tumor growth inhibition in STn-expressing tumor xenograft cancer models with no evidence of overt toxicity.
41 citations
Cites background from "A detailed study of the periodate o..."
...This periodate oxidation of terminal sialic acids removes the side chain, giving rise to the C7 analogs of these sialic acids.(32) The commercially available mAbs B72....
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TL;DR: It is concluded that sialylated KS proteoglycans are endogenous human airway ligands that bind Siglec-8 and may regulate allergic inflammation.
Abstract: Human siglecs are a family of 14 sialic acid-binding proteins, most of which are expressed on subsets of immune cells where they regulate immune responses. Siglec-8 is expressed selectively on human allergic inflammatory cells-primarily eosinophils and mast cells-where engagement causes eosinophil apoptosis and inhibits mast cell mediator release. Evidence supports a model in which human eosinophils and mast cells bind to Siglec-8 sialoglycan ligands on inflammatory target tissues to resolve allergic inflammation and limit tissue damage. To identify Siglec-8-binding sialoglycans from human airways, proteins extracted from postmortem human trachea were resolved by size-exclusion chromatography and composite agarose-acrylamide gel electrophoresis, blotted and probed by Siglec-8-Fc blot overlay. Three size classes of Siglec-8 ligands were identified: 250 kDa, 600 kDa and 1 MDa, each of which was purified by affinity chromatography using a recombinant pentameric form of Siglec-8. Proteomic mass spectrometry identified all size classes as the proteoglycan aggrecan, a finding validated by immunoblotting. Glycan array studies demonstrated Siglec-8 binding to synthetic glycans with a terminal Neu5Acα2-3(6-sulfo)-Gal determinant, a quantitatively minor terminus on keratan sulfate (KS) chains of aggrecan. Treating human tracheal extracts with sialidase or keratanase eliminated Siglec-8 binding, indicating sialylated KS chains as Siglec-8-binding determinants. Treating human tracheal histological sections with keratanase also completely eliminated the binding of Siglec-8-Fc. Finally, Siglec-8 ligand purified from human trachea extracts induced increased apoptosis of freshly isolated human eosinophils in vitro. We conclude that sialylated KS proteoglycans are endogenous human airway ligands that bind Siglec-8 and may regulate allergic inflammation.
39 citations
TL;DR: A glycoconjugate vaccine strategy was selected to elicit opsonizing anti-capsular polysaccharide (anti-CPS) IgG antibodies, yielding functional activity in vitro and protection against a lethal challenge in vivo, all features of a T cell-dependent response.
Abstract: Streptococcus suis serotype 2 is an encapsulated bacterium and one of the most important bacterial pathogens in the porcine industry. Despite decades of research for an efficient vaccine, none is currently available. Based on the success achieved with other encapsulated pathogens, a glycoconjugate vaccine strategy was selected to elicit opsonizing anti-capsular polysaccharide (anti-CPS) IgG antibodies. In this work, glycoconjugate prototypes were prepared by coupling S. suis type 2 CPS to tetanus toxoid, and the immunological features of the postconjugation preparations were evaluated in vivo In mice, experiments evaluating three different adjuvants showed that CpG oligodeoxyribonucleotide (ODN) induces very low levels of anti-CPS IgM antibodies, while the emulsifying adjuvants Stimune and TiterMax Gold both induced high levels of IgGs and IgM. Dose-response trials comparing free CPS with the conjugate vaccine showed that free CPS is nonimmunogenic independently of the dose used, while 25 μg of the conjugate preparation was optimal in inducing high levels of anti-CPS IgGs postboost. With an opsonophagocytosis assay using murine whole blood, sera from immunized mice showed functional activity. Finally, the conjugate vaccine showed immunogenicity and induced protection in a swine challenge model. When conjugated and administered with emulsifying adjuvants, S. suis type 2 CPS is able to induce potent IgM and isotype-switched IgGs in mice and pigs, yielding functional activity in vitro and protection against a lethal challenge in vivo, all features of a T cell-dependent response. This study represents a proof of concept for the potential of glycoconjugate vaccines in veterinary medicine applications against invasive bacterial infections.
34 citations
References
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TL;DR: This chapter discusses the different aspects of thiobarbituric acid assay of sialic acid, which is suitable for measuring the release of bound sialoic acid by sialidase and hydrolysis of sIALic acid-containing material must be carried out for the measurement of total sialsic acids.
6,264 citations
TL;DR: This chapter presents literature data on the high-resolution, 1H-NMR spectroscopy of carbohydrates derived from glycoconjugates and discusses the results for carbohydrates related to the glycoproteins of N-glycosylic type.
Abstract: Publisher Summary This chapter discusses the application of high-resolution, 1H-nuclear magnetic resonance (NMR) spectroscopy to the structural analysis of carbohydrates related to glycoproteins. Glycoproteins are biopolymers consisting of a polypeptide backbone bearing one or more covalently linked carbohydrate chains. The carbohydrate chains of glycoproteins may be classified according to the type of linkage to the polypeptide backbone. N-Glycosylic chains are attached to the amide group of asparagine (Asn), whereas the O-glycosylic chains are linked to the hydroxyl group of amino acid residues such as serine (Ser), threonine (Thr), and hydroxylysine (Hyl). The high-resolution, 1H-NMR spectroscopy technique, in conjunction with methylation analysis, is extremely suitable for the structural studies of N-, as well as on O-, glycosylic glycans. For the interpretation of the 1H-NMR spectrum of a carbohydrate chain in terms of primary structural assignments, the concept of “structural reporter groups” was developed. This means that the chemical shifts of protons resonating at clearly distinguishable positions in the spectrum, together with their coupling constants and the line widths of their signals, bear the information essential to permit the assigning of the primary structure. This chapter presents literature data on the high-resolution, 1H-NMR spectroscopy of carbohydrates derived from glycoconjugates. It also discusses the results for carbohydrates related to the glycoproteins of N-glycosylic type.
797 citations
TL;DR: This simple method of specifically introducing a radioactive label into cell surface sialic acids is useful in the study of cell surfaceSialic acid-containing glycoproteins.
482 citations
230 citations
01 Jan 1982
TL;DR: The discovery and the widespread occurrence of the sialic acids in mammalian tissues has been correlated with a range of different biological functions (see chapter J), and the known spectrum of derivatives covered in this chapter continues to expand.
Abstract: The discovery and the widespread occurrence of the sialic acids in mammalian tissues (Blix 1936, Klenk 1941) has been correlated with a range of different biological functions (see chapter J) which continues to expand. Although the literature on sialic acid occurrence is large (Gottschalk 1960, Blix and Jeanloz 1969, Tuppy and Gottschalk 1972, Schauer 1973, Ng and Dain 1976), it has been essentially limited to the vertebrates and some examples from the Echinodermata and Bacteria. Only one survey of sialic acid distribution in different phyla has been published (Warren 1963). Current data on sialic acid structure is compiled in Table 1, introducing the known spectrum of derivatives covered in this chapter.
168 citations