Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.53 (sialidase)
2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the first stage of infection, the paramyxovirus Sendai virus attaches to host cells by recognizing specific receptors on the cell surface. Productive virus-cell interactions result in membrane fusion between the viral envelope and the cell surface membrane. It has recently been shown that the ganglioside GD1a and its more complex homologs GT1b and GQ1b are cell surface receptors for Sendai virus. We report in this paper that the temperature-sensitive mutant ts271 of the Enders strain of Sendai virus lacks the viral attachment protein HN and the biological activities of hemagglutination and sialidase activity associated with it when the virus is grown at 38 degrees C. This HN- virus was unable to infect or agglutinate conventional host cells that contained receptor gangliosides and were readily infected by the parental wild-type virus. The HN- virus did, however, attach to and infect Hep G2 cells, a line of hepatoma cells that retains the asialoglycoprotein receptor (ASGP-R) upon continuous culture. This receptor is a mammalian lectin that recognizes galactose- or N-acetylgalactosamine-terminated proteins. In accordance with the known properties of this receptor, infection by the HN- virus was abolished by treatment of Hep G2 cells with sialidase, by the presence of Ca2+ chelators, and by competition with N-acetylgalactosamine, asialoorosomucoid, and antibody to the receptor. F, the only glycoprotein on the HN- virus, was shown to compete with the galactose-terminated protein asialoorosomucoid for the ASGP-R. The ability of the HN- virus to cause cell-cell fusion of Hep G2 cells indicated that attachment of this virus to the ASGP-R still permitted viral entry by its usual mode--i.e., membrane fusion at the cell surface. These results open up the possibility that enveloped viruses, which contain glycosylated proteins or lipids, may make use of naturally occurring lectins in addition to their normal receptors as a means of attachment to host cells.
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PMID:An alternative route of infection for viruses: entry by means of the asialoglycoprotein receptor of a Sendai virus mutant lacking its attachment protein. 298 37

Lectin binding affinities were described in human submandibular gland (SMG) in the paraffin sections following alpha-amylase, sialidase, and trypsin digestions. Lectins in the present study were used Con A (Glc, Man binding lectins), PNA, and SBA(Gal, GalNAc), RCA-1(Gal), DBA(GalNAc), WGA(GlcNAc), and UEA-1(Fuc). Lectin stainings in serous and mucous acinar cells and ductal epithelia were reported to compare enzyme treated and nontreated sections. Amylase treatment showed increasing Con A staining in connective tissue fibers and no marked changes in SMG to lectin bindings. Sialidase digestion was characteristically intense in PNA and SBA bindings in SMG cells, and also enhanced staining to UEA-1 in serous and duct cells and to WGA in mucous and duct cells were noted. Trypsin digestion indicated a slight increase to Con A binding, and was relatively strong to UEA-1 in serous and duct cells and a little strong to WGA. The results suggested that SMG serous cells contain higher amounts of Gal, GalNAc, and Fuc residues; and mucous cells were also abundant in Gal, GalNAc, and GlcNAc residues.
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PMID:Different bindings to lectin in human submandibular gland after enzymatic digestion. 308 93

We investigated the structure of glycoconjugates contained within the secretory end-pieces and ductal segments in the rabbit submandibular and sublingual glands. Glycosidic sequences were examined by means of enzymatic degradation with specific glycosidases (sialidase, alpha-fucosidase, beta-galactosidase, alpha-mannosidase) followed by lectin binding with PNL-HRP, WPL-HRP, WGL-HRP, SBL-HRP, Con A-HRP. It was found that this procedure represents a valid tool for studying carbohydrates, in so far as their characterization and localization were based only on colour reactions. In particular, this research showed that sialic acid was present in the terminal dimers sialic acid-beta-galactose and sialic acid-N-acetyl-D-galactosamine within the submandibular gland, whereas in the sublingual gland it was only present as the sequence sialic acid-beta-galactose. Conversely, fucose had as the subterminal sugar N-acetyl-D-glucosamine in both glands. Also, elucidations about structural sequences concerning other non-terminal sugars were obtained.
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PMID:Visualization of carbohydrate chains in rabbit salivary glands by means of enzymatic degradation and plant lectins. 314 37

The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.
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PMID:Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors. 326 79

Glycolipids of murine lymphoma cell lines with low metastatic (Eb) and high metastatic (ESb) potentials have been investigated. The Eb cell line was characterized by a high quantity of gangliotriaosylceramide (Gg3), gangliotetraosylceramide (Gg4), GM1b, and a new type of disialoganglioside, termed GD1 alpha. In contrast, the high metastatic ESb cell line was characterized by the absence of these glycolipids and instead by the presence of GM3, GM2, GM1a, GD1a, and GD1b gangliosides. A clear cell surface reactivity with monoclonal antibody anti-Gg3 (2D4) was observed only in Eb cells. Thus, Eb cells are distinct from ESb cells in their ability to add the GalNAc residue to LacCer, supplying Gg3 for synthesis of a series of glycolipids via an asialogangliotetraosyl pathway, while ESb cells are capable of synthesizing GM3, which initiates synthesis of ganglio-series gangliosides GM2, GM1a, GD1a, and GD1b. While disialogangliosides of ESb cells were identified as GD1a and GD1b, a disialoganglioside isolated from Eb cells was characterized as having a novel structure (referred to as GD1 alpha) as follows: (formula; see text) Thus, Eb and ESb cells are clearly different in their qualitative sialylation patterns, i.e., the position of sialic acid residues. Cell surface labeling with galactose-oxidase/NaB[3H]4 revealed a high exposure of Gg3 and Gg4 at the Eb cell surface, while both labels were absent in ESb cells. In contrast, ESb cells showed a substantial label at GM1a, which was greatly enhanced after sialidase treatment.
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PMID:Qualitative differences in position of sialylation and surface expression of glycolipids between murine lymphomas with low metastatic (Eb) and high metastatic (ESb) potentials and isolation of a novel disialoganglioside (GD1 alpha) from Eb cells. 348 80

An oligosaccharide alditol, dHex-GalNAc-Gal-Gal-GalNAcol, has been isolated from polysialoglycoprotein, which was derived from the unfertilized eggs of Savelinus leucomaenis pluvius (a salmonid fish, Iwana in Japanese), by alkaline borohydride treatment followed by exhaustive digestion with sialidase. First, the structure of the terminal dHex residue in the above pentasaccharide has been assigned as 6-deoxyaltrose (= dAlt in pyranoid form) by a combination of structural methods (GLC, TLC, mass spectrometry, and 400-MHz 1H-NMR spectroscopy). The occurrence of a 6-deoxyhexose other than L-fucose in glycoprotein has not been previously reported. Next, the absolute configuration of this unusual sugar residue has been assigned as D on the basis of the exciton-splitting study of tris-p-bromobenzoate derivatives of methyl 6-deoxyaltrosides. The usefullness of this circular dichroic exciton-splitting method in the determination of the absolute configuration of carbohydrate components, only available in minute amounts, is emphasized. The anomeric configuration of the glycosidic linkage of the D-altropyranosyl residue was deduced from 400-MHz 1H NMR spectroscopy. The 6-deoxy-beta-D-altropyranosyl residue thus established has the same configuration as alpha-L-fucose but with the C-5 methyl group inverted, suggesting that the biosynthetic incorporation of D-dAlt parallels that of L-fucose, and a possible pathway is also considered.
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PMID:Identification and determination of absolute and anomeric configurations of the 6-deoxyaltrose residue found in polysialoglycoprotein of Salvelinus leucomaenis pluvius eggs. The first demonstration of the presence of a 6-deoxyhexose other than fucose in glycoprotein. 366 14

Following several model experiments, conditions were developed for optimal deglycosylation of tracheal mucin glycoproteins. Exposure of rigorously dried material to trifluoromethanesulfonic acid at 0 degree C for up to 8 h results in cleavage of essentially all fucose, galactose, and N-acetylglucosamine, about 80% of the N-acetylneuraminic acid (NeuNAc), and a variable amount of N-acetylgalactosamine (GalNAc), the sugar involved in linkage to protein. Residual N-acetylneuraminic acid is sialidase susceptible and apparently in disaccharide units, presumably NeuNAc2----GalNAc. The remaining N-acetylgalactosamine is mostly present as monosaccharides, and a few Gal beta 1----3GalNAc alpha units are also present; both are cleaved by appropriate enzymatic treatment. The saccharide-free proteins obtained from either human or canine mucin glycoproteins have molecular weights of about 100,000 and require chaotropic agents or detergents for effective solubilization.
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PMID:Deglycosylation studies on tracheal mucin glycoproteins. 367 55

gpL115, the surface sialoglycoprotein that is defective in lymphocytes of Wiskott-Aldrich syndrome patients has been purified from large scale cultures of the lymphoblastoid line CEM. The purification entails cell lysis and solubilization of gpL115 with the detergent Nonidet P-40, sequential affinity chromatography on lentil lectin-Sepharose, wheat germ lectin-Sepharose, and, after treatment with sialidase, on peanut lectin-Sepharose. Sepharose CL-6B gel filtration removes residual protein contaminants and transfers asialo-gpL115 from Nonidet P-40-containing to sodium dodecyl sulfate-containing buffer. The yield, 1300 micrograms of homogeneous protein/10(11) cells, represents greater than 60% recovery. The amino acid composition of gpL115 has several atypical features including low lysine content, high proline content, and very high content of hydroxyamino acids (12.5 residues of serine and 12.5 residues of threonine/100 amino acids). Total carbohydrate content of gpL115 is very high, i.e. 52% for the asialo-molecule. The major carbohydrate residues of asialo-gpL115 are galactose and N-acetylgalactosamine in approximately equimolar amounts (25 and 22 residues/100 amino acids, respectively) plus severalfold lower amounts of N-acetylglucosamine, fucose, and mannose.
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PMID:Purification and chemical composition of gpL115, the human lymphocyte surface sialoglycoprotein that is defective in Wiskott-Aldrich syndrome. 371 Oct 98

Crude extracts from Salvia sclarea seeds were known to contain a lectin which specifically agglutinates Tn erythrocytes (Bird, G. W. G., and Wingham, G. (1974) Vox Sang. 26, 163-166). We have purified the lectin to homogeneity by ion-exchange chromatography and affinity chromatography. The agglutinin was found to be a glycoprotein of Mr = 50,000, composed of two identical subunits of Mr = 35,000 linked together by disulfide bonds. The purified lectin agglutinates specifically Tn erythrocytes and, at higher concentrations, also Cad erythrocytes. Native A, B, or O red blood cells are not agglutinated by the lectin and, even after treatment with sialidase or papain, these cells are not recognized. Tn red cells present 1.45 X 10(6) accessible sites to the lectin which binds to these erythrocytes with an association constant of 1.8 X 10(6) M-1. On Cad red cells, 1.73 X 10(6) sites are accessible to the lectin which binds with an association constant of 1.0 X 10(6) M-1. The carbohydrate specificity of the S. sclarea lectin has been determined in detail, using well defined monosaccharide, oligosaccharide, and glycopeptide structures. The lectin was found to be specific for terminal N-acetylgalactosamine (GalNAc) residues. It binds preferentially alpha GalNAc determinants either linked to Ser or Thr (as in Tn structures) or linked in 1-3 to a beta GalNAc or to an unsubstituted beta Gal. Although more weakly, the lectin binds beta GalNAc residues linked in 1-4 to a beta Gal (as in Cad structures). It does not recognize beta GalNAc determinants linked in 1-3 to a Gal (as in globoside) or the alpha GalNAc residues of blood group A structures.
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PMID:Isolation and characterization of an N-acetylgalactosamine specific lectin from Salvia sclarea seeds. 377 23

The type 2 fimbrial lectin of Actinomyces naeslundii WVU45 mediated the binding of this bacterium to glycosphingolipids chromatographed on thin-layer silica gel plates. Radioiodinated bacteria attached to GM1, GD1b, and globoside. After chromatograms were treated with sialidase, the bacteria also bound to GD1a and GT1b. The actinomyces lectin apparently recognized the Gal beta 3GalNAc termini of these gangliosides and the GalNAc beta 3Gal terminus of globoside, suggesting that glycolipids containing these sequences may serve as receptors for A. naeslundii on mammalian cells.
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PMID:Binding of Actinomyces naeslundii to glycosphingolipids. 380 48


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