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)

Soluble extracts of Bufo ovaries agglutinate sialidase-treated rabbit erythrocytes. Unlike other amphibian lectins this agglutination activity does not require the presence of calcium ions. It is specifically inhibited by D-galactose and its derivatives. Thiodi-D-galactoside is the most potent saccharide inhibitor followed by lactose and methyl-beta-D-galactoside, respectively. D-Fucose, D-glucose and D-mannose do not inhibit the activity at concentrations at or above 100 mM. The lectin has been purified 500-fold to apparent homogeneity from the ovaries by salt extraction and affinity chromatography on lactose-aminophenyl-agarose, with a yield of about 0.2%. The molecular mass determined by gel filtration under native conditions was 30 kDa; polyacrylamide gel electrophoresis in SDS gave a molecular mass of 15 kDa, suggesting that the lectin is a dimer. The lectin has an isoelectric point of 40 and contains a high proportion of acidic amino acids.
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PMID:Purification and some characteristics of a beta-galactoside binding soluble lectin from amphibian ovary. 366 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

The presence of Thomsen-Friedenreich antigen (T-Ag) against bladder mucosa in bladder tumor cases and control individuals was examined by the immunoperoxidase and the immunofluorescein method using labelled lectin. T-Ag was negative in all 15 cases of non-malignant bladder epithelium, and positive on the cell surface after sialidase treatment (cryptic T-Ag positive). In the 37 out of 72 bladder tumor cases, however, cryptic T-Ag was positive, and in the remaining 35 cases T-Ag was positive or negative after sialidase treatment. Furthermore 55 cases which had received the first treatment by TUR-Bt were investigated. Thirteen of the 31 cryptic T-Ag positive cases recurred during observation after operation whereas 22 of the 24 T-Ag positive or cryptic T-Ag negative cases recurred, the rate being significantly higher for the latter. In addition, the disease-free interval was absolutely longer in the cryptic T-Ag positive cases than in T-Ag positive or cryptic T-Ag negative cases. The exploration of T-Ag in bladder cancer may be valuable for predicting the clinical course after TUR-Bt.
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PMID:[The study on Thomsen-Friedenreich antigen in bladder tumor]. 389 52

It is reported that concanavalin A (conA) and wheat germ agglutinin (WGA) have a differential binding pattern on normal mouse spleen lymphocytes and the surface of Dalton's lymphoma cells. It is suggested that sialic acid on the cell surface controls the expression of lectin binding sites. Further, it has been observed that the increased release of sialic acid from cell surfaces after cis-dichlorodiammine platinum (II) (cis-Platin) treatment is due to the increased activity of sialidase.
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PMID:Differential binding of conA and WGA on the cell surface, the role of sialic acid in their expression and the increased activity of sialidase after cis-Platin treatment. 391 32

The asparagine-linked sugar chains of rabbit immunoglobulin G (IgG) and its Fc and Fab fragments were quantitatively liberated from the polypeptide portions by hydrazinolysis followed by N-acetylation and NaB3H4 reduction. After fractionation by paper electrophoresis, lectin chromatography, and gel filtration, their structures were studied by sequential exoglycosidase digestion in combination with methylation analysis. Rabbit IgG was shown to contain 2.3 mol of asparagine-linked sugar chains per molecule distributed in both the Fc and Fab fragments. The sugar chains were of the biantennary complex type containing four cores: Man alpha 1----6(Man alpha 1----3)(+/- GlcNAc beta 1----4)Man beta 1----4GlcNAc beta 1----4(+/- Fuc alpha 1----6)-GlcNAc. A total of 16 distinct neutral oligosaccharide structures was found after sialidase treatment. The galactose residue in the monogalactosylated oligosaccharides was present on either the alpha 1----3 or alpha 1----6 side of the trimannosyl core. The Fab fragments contained neutral, monosialylated, and disialylated oligosaccharides, whereas the Fc fragment contained only neutral and monosialylated structures. The oligosaccharides isolated from the Fab fragments also contained more galactose and bisecting N-acetylglucosamine residues than those from the Fc fragments.
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PMID:Structures of the sugar chains of rabbit immunoglobulin G: occurrence of asparagine-linked sugar chains in Fab fragment. 407 13

The effects of the sequential application of specific glycosidases on surfaces of living mammalian cells were studied with respect to their ability to bind the beta-galactoside-specific lectin, Ricinus communis agglutinin (RCA). Sialidase and beta-galactosidases from different sources were tested for their actions on two strains of mouse lymphoma cells differing markedly in their metastatic potential. Binding studies were performed by quantitative flow cytometry with fluorescent RCA, and numbers of specific binding sites and equilibrium association constants for the lectin on living cells were determined before and after the various enzyme treatments. Although the number of binding sites for native and sialidase-treated cells were almost identical for both cell strains, differences in the apparent affinity constants could be detected. Differences between the two strains became even more pronounced, also with respect to the number of binding sites, after treatment with beta-galactosidases from S. pneumoniae and from bovine testis. It is suggested that such combined strategies provide valuable tools for the differentiation of surface carbohydrate moieties on intact living cells, especially for comparative purposes.
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PMID:The effect of specific glycosidases on Ricinus communis agglutinin binding to cell surfaces of two tumor sublines. A comparative flow-cytometric study. 621 Jan 45

Cultured fibroblasts from patients with the lysosomal storage disease, mucolipidosis II, produce complex glycosylated lysosomal enzymes which are preferentially excreted presumably due to the absence of specific phosphomannosyl recognition residues needed for intracellular retention. Complex glycosylated hydrolases are also produced by fibroblasts from patients with mucolipidosis I but an abnormal excretion is not apparent in this disorder. Intra- and extracellular distribution, lectin binding, and specific endocytosis were criteria used to compared the properties of intra- and extracellular beta-hexosaminidase derived from mucolipidosis I and normal fibroblast cultures. Mucolipidosis I fibroblasts did not hyperexcrete beta-hexosaminidase when maintained in serum-free medium. Using the specificity of ricin binding to terminal galactosyl residues, the most galactosylated forms of the enzyme derived from mucolipidosis I cell extracts and culture fluids were found in the mucolipidosis I cell extracts (50% of total enzyme). Mucolipidosis I-excreted beta-hexosaminidase which was eluted from ricin-120-Sepharose, was a high-uptake form in endocytosis experiments while unbound enzyme was a low-uptake form. These data suggest that beta-hexosaminidase molecules contained phosphomannosyl residues necessary for receptor-mediated endocytosis as well as galactosyl residues on the same molecule. The co-existence of complex chains with high-mannose chains did not interfere with the phosphomannose-mediated endocytosis of beta-hexosaminidase nor with the retention of endogenous enzyme. We can speculate that since complex oligosaccharide chains in the mucolipidosis I cellular enzyme persist due to a sialidase deficiency, more extensive sialylation of cellular enzyme in normal fibroblasts probably occurs at some point during post-translational processing. However, the presence of sialidase in normal cells initiates complex chain trimming in the lysosomes resulting in a less glycosylated end product.
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PMID:Effect of the co-existence of galactosyl and phosphomannosyl residues on beta-hexosaminidase on the processing and transport of the enzyme in mucolipidosis I fibroblasts. 622 17

Carbohydrate-lectin interactions serve as the basis of recognition by phagocytic cells of particles and of various target cells. Such interactions occur in the following systems: between sugars on the surface of the phagocytic cells and lectins on the surface of other cells--the best studied example is the binding of mannose-specific Escherichia coli and related organisms via their surface lectins to oligo-mannose residues on macrophages; between lectins on the surface of phagocytic cells and sugars on particles or other cells--phagocytosis of zymosan and of sialidase-treated erythrocytes, mediated respectively by mannose-specific and galactose-specific lectins on macrophages, belongs to this category; by extracellular lectins that form bridges between sugars on both types of cell--as shown by enhancement of phagocytosis of staphylococci by wheat germ agglutinin, and by lectin-dependent killing of target cells by macrophages. These interactions may play an important role in the activities of phagocytic cells in vivo. They may provide an initial host defense mechanism immediately after microbial infection, operate in tissues where phagocytic activity is poor, and participate in tumor rejection.
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PMID:Carbohydrates as recognition determinants in phagocytosis and in lectin-mediated killing of target cells. 624 Mar 7


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