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)

A sialic acid-binding lectin, AchatininH (ATNH), having unique specificity towards 9-O-acetylneuraminic acid, has been purified and characterized. The specificity of this lectin for O-acetylsialic acids was studied in detail, using various sialic acid derivatives and sialoglycoproteins. The potent inhibition of hemagglutination by bovine submaxillary mucin (BSM), which contains 9(7,8)-O-acetylsialic acid and by free 9-O-acetylneuraminic acid confirms the preferential affinity towards this sugar. Further support for the role of O-acetylsialic acid was obtained by sialidase treatment of BSM. O-Deacetylation of the sialic acid residue abolished its inhibitory potency. Moreover, when the trihydroxypropyl side chain of the sialic acid molecule was modified by periodate-borohydride treatment, the truncated C7-sialic acid was unable to bind ATNH. This result suggests that the glycerol side chain of Neu5Ac, especially the C-8 and/or C-9 portion is an important determinant for ATNH. The hemagglutination-inhibition results using several mono-, di-, and tri-saccharides containing terminal sialic acid and various sialoglycoproteins reveals that ATNH preferentially binds the alpha-(2-->6)-linked sialic acid. Furthermore, beta-D-GlcNAc-(1-->3)-[alpha-NeuGc-(2-->6)]-GalNAc-ol was found to be the best ligand for ATNH.
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PMID:The specificity of the binding site of AchatininH, a sialic acid-binding lectin from Achatina fulica. 773 61

Recognition of receptors on sialidase-treated polymorphonuclear leukocytes (PMNs) by the Gal/GalNAc lectin associated with the type 2 fimbriae of certain strains of actinomyces results in activation of the PMNs, phagocytosis, and destruction of the bacteria. In the present study, plant lectins were utilized as probes to identify putative PMN receptors for the actinomyces lectin. The Gal-reactive lectin from Ricinus communis (RCAI), the Gal/GalNAc-reactive lectins from R. communis (RCAII) and Bauhinia purpurea (BPA), as well as the Gal beta 1-3GalNAc-specific lectins from Arachis hypogaea (PNA) and Agaricus bisporus (ABA) inhibited killing of Actinomyces naeslundii WVU45 by sialidase-treated PMNs. These five lectins detected a 130-kDa surface-labeled glycoprotein on nitrocellulose transfers of PMN extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This glycoprotein was revealed only after treatment of the transfers with sialidase, a condition analogous to the sialidase dependence of the lectin-mediated biological responses of the PMNs to the actinomyces. The mannose-reactive lectin concanavalin A did not inhibit killing of the actinomyces and failed to detect the 130-kDa glycoprotein but did block PMN-dependent killing of Escherichia coli B, a bacterium that possesses mannose-sensitive fimbriae. Therefore, the PMN glycoprotein receptor for A. naeslundii is clearly distinct from those recognized by E. coli. Two major putative glycolipid receptors were also identified by actinomyces and RCAI overlays on sialidase-treated thin-layer chromatograms of PMN gangliosides. Thus, both a 130-kDa glycoprotein and certain gangliosides are implicated in the attachment of the actinomyces to PMNs.
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PMID:Putative glycoprotein and glycolipid polymorphonuclear leukocyte receptors for the Actinomyces naeslundii WVU45 fimbrial lectin. 779 78

Gangliosides GM1 [3H-labeled at the sphingosine (Sph) moiety] and GM2 [3H-labeled at the Sph or N-acetylgalactosamine (GalNAc) moiety] were administered to cultured Neuro2a cells for varying pulse (1-4 h) and chase (up to 4 h) periods, and their metabolic processing was followed. The main and earliest formed 3H-metabolites of [Sph-3H]GM1 were GM2, asialo-GM1 asialo-GM2, and lactose-ceramide, and those of [Sph-3H]GM2 were asialo-GM2 and lactose-ceramide. The asialo-GM1 and asialo-GM2 formed were isolated and chemically characterized. [3H]Asialo-GM2 was produced in identical amounts after treatment with equimolar [Sph-3H]GM2 and [GalNAc-3H]GM2. At low temperature or in the presence of chloroquine, the formation of all 3H-metabolites, including asialo-GM2 and asialo-GM1, was undetectable, indicating that ganglioside metabolic processing was an endocytosis- and lysosome-dependent process. These results demonstrate that in Neuro2a cells exogenous GM1 (and GM2) is mainly degraded through the pathway GM1-->GM2-->asialo-GM2-->-->Sph, with a minor fraction of GM1 undergoing degradation with the sequence GM1-->asialo-GM-1-->asialo-GM2-->-->Sph. These findings are consistent with the hypothesis that Neuro2a cells contain a sialidase (likely of lysosomal nature) affecting ganglioside GM1 and GM2. The sialidase-mediated degradative pathway of GM1 and GM2 in Neuro2a cells might be related to the tumoral nature of these cells.
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PMID:The degradative pathway of gangliosides GM1 and GM2 in Neuro2a cells by sialidase. 779 45

The mucin-type carbohydrate Tn cryptantigen (GalNAc alpha 1-O-Ser/Thr, where GalNAc is N-acetyl-D-galactosamine) is expressed in many carcinomas, in haemopoietic disorders including the Tn syndrome, and on human immunodeficiency virus (HIV) coat glycoproteins, but is not expressed on normal, differentiated cells because of the expression of a Tn-processing galactosyltransferase. Using Jurkat T leukaemic cells which express high levels of Tn antigen due to deficient Tn galactosylation, we have established the Tn antigen-mediated gene transfer and demonstrate the considerable efficiency of this approach. We used poly(L-lysine) conjugates of the monoclonal antibody 1E3 directed against the Tn antigen to deliver the luciferase and beta-galactosidase reporter genes to Jurkat cells by receptor-mediated endocytosis. Addition of unconjugated 1E3 reduced transfection efficiency in a concentration-dependent manner and incubation with free GalNAc abolished DNA transfer completely, indicating that gene delivery is indeed mediated by the Tn antigen. Pre-treatment of Jurkat cells with Vibrio cholerae sialidase, which uncovers additional Tn antigens, resulted in an improvement of gene transfection. Both human and chicken adenovirus particles attached to the DNA/polylysine complex strongly augmented transgene expression. When the beta-galactosidase (lacZ) gene was delivered to Jurkat cells by Tn-mediated endocytosis, up to 60% of the cells were positive in the cytochemical stain using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) as a chromogenic substrate. The efficiency of the transferrin receptor-mediated DNA uptake into Jurkat cells was comparatively low, although these cells were shown to express considerable amounts of transferrin receptor. We show here that a mucin-type carbohydrate antigen mediates highly efficient DNA uptake by endocytosis into Jurkat T cells. This method represents a 50-fold improvement of Jurkat cell transfection efficiency over other physical gene transfer techniques. Specific gene delivery to primary cancer cells exhibiting Tn epitopes may especially be desirable in immunotherapy protocols.
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PMID:Carbohydrate receptor-mediated gene transfer to human T leukaemic cells. 782 4

Sialoglycoconjugates were investigated in the bovine sublingual gland by direct visualization of sialic acid with specific lectins (LPA, SNA) and by histochemical procedures combined with sialidase digestion and lectins. The most reactive histological structures were found to be acini which contained glycoconjugates with terminal disaccharides consisting of sialic acid linked to galactose or N-acetylgalactosamine. Resistance to periodate oxidation was interpreted as demonstrating a relevant presence of C7, C8 and C9 acetylated sialic acids. KOH-Sialidase-DBA and KOH-Alcian blue sequences allowed the identification of C4 acetylated sialic acids.
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PMID:Variety of sialic acids occurring in the bovine sublingual gland. 789 45

The release of 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN, deaminoneuraminic acid) residues from their alpha-ketosidic linkage is required to determine the structural and functional role of KDN-glycoconjugates in sources as disparate as trout egg polysialoglycoproteins and human cancers. We report for the first time the isolation and characterization of a novel type of sialidase (KDNase), which specifically hydrolyzes KDN ketosidic but not N-acylneuraminyl linkages. KDNase activity was assayed using 4-methylumbelliferyl KDN (4-MU-KDN). A KDNase-producing microorganism was identified as Sphingobacterium multivorum. The affinity-purified enzyme was designated KDNase SM to denote its origin and that it was free of N-acylneuraminidase, proteolytic, and other glycosidase activities. KDNase SM activity toward 4-MU-KDN was not inhibited by the N-acylneuraminidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. KDNase SM released free KDN from naturally occurring substrates, including (KDN)GM3, KDN-glycoprotein, which bears a number of O-linked chains of KDN alpha 2-->3Gal beta 1-->3GalNAc alpha 1-->3 (KDN alpha 2-->(-->8KDN alpha 2-->)n-->6)GalNAc alpha 1-->, and the biantennary complex-type of N-glycan, KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4GlcNAc beta 1-->4GlcNAc. KDNase SM thus exhibited a broad linkage specificity and was able to hydrolyze the KDN residues ketosidically linked alpha 2-->3, alpha 2-->6, and alpha 2-->8. The enzyme did not release Neu5Ac or Neu5Gc from 4-MU-Neu5Ac, N-acetyl-neuraminyllactose, colominic acid, or other Sia(Neu5Ac or Neu5Gc)-containing glycoconjugates.
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PMID:Discovery of a new type of sialidase, "KDNase," which specifically hydrolyzes deaminoneuraminyl (3-deoxy-D-glycero-D-galacto-2-nonulosonic acid) but not N-acylneuraminyl linkages. 806 73

Two gangliosides were efficiently synthesized from asialo-GM1 (Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer) and cytidine 5'-phosphate-N-acetylneuraminic acid (CMP-NeuAc) by using sialyltransferases in rat liver Golgi vesicles in vitro. These gangliosides were rapidly purified by a combination of anion exchange and reverse-phase column chromatographies. The ganglioside structures were determined by TLC analysis, treatment with a sialidase from Salmonella typhimurium LT2, which specifically hydrolyzes alpha 2-3 N-acetylneuraminic acid (NeuAc alpha 2-3) linkages, TLC immunostaining, and 1H-NMR spectroscopy. One of the gangliosides was identified as GD1 alpha [Neu-Ac alpha 2-3Gal beta 1-3(NeuAc alpha 2-6)GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer]. The other ganglioside was determined to be GM1b (NeuAc alpha 2-3Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer), which has been reported in a previous study [Pohlentz, G., Klein, D., Schmitz, D., Schwarzmann, G., Peter-Katalinic, J. & Sandhoff, K. (1988) Biol. Chem. Hoppe-Seyler 369, 55-63]. Finally, GM1b and GD1 alpha were obtained from asialo-GM1 as a starting material in 8.1% and 1.2% overall yields, respectively. This study also suggests that the novel synthetic pathway asialo-GM1-->GM1b-->GD1 alpha may exist in rat liver.
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PMID:In vitro synthesis of disialoganglioside (GD1 alpha) from asialo-GM1 using sialyltransferases in rat liver Golgi vesicles. 816 48

The cDNA encoding GM2 activator was expressed in the Escherichia coli/pT7-7 system. The yield of the GM2 activator with greater than 99% purity was about 3 mg per liter culture. The recombinant GM2 activator was found to be as active as that isolated from human kidney. The availability of the recombinant GM2 activator enabled us to critically examine the specificity of this activator protein. Our results show that the specificity of GM2 activator is not as strict as that reported previously. Although GM2 activator stimulates most efficiently the degradation of GM2 carried out by beta-N-acetylhexosaminidase A (Hex A), this activator also stimulates the following reactions: (a) conversion of GM2 to GA2 by clostridial sialidase; (b) hydrolysis of GalNAc from dipalmitoylphosphatidylethanolamine-II3NeuAcGgOse3 by Hex A; and (c) liberation of Gal from GM1 by beta-galactosidase at a high activator concentration. Thus, this activator does not differentiate between GM2 and dipalmitoylphosphatidylethanolamine-II3NeuAcGgOse3 or between Hex A and clostridial sialidase. The micellar forms of GD2 and GalNAc-GD1a were found to be more readily hydrolyzed by Hex A than GM2 in the absence of GM2 activator. Our results also show that saposin B can enhance the stimulatory activity of GM2 activator, but it cannot promote the stimulatory activity of sodium taurodeoxycholate. Taken together, our results suggest that the mechanism of action of GM2 activator is different from saposin B, and the action of GM2 activator is more than to solubilize lipid substrates. The effectiveness of GM2 activator in stimulating the hydrolysis of GM2 may be due to its ability to recognize the specific trisaccharide structure of the GM2 epitope, GalNAc beta 1-->4(NeuAc alpha 2-->3)Gal-, and to modify the GalNAc-NeuAc interaction in this structure.
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PMID:Expression and specificity of human GM2 activator protein. 820 33

The Tn antigen (GalNAc alpha 1-O-Ser/Thr) is a disease-related O-linked (mucin-type) carbohydrate neoantigen which is expressed in idiopathic Tn syndrome, AIDS, T-cell lymphoma and in many carcinomas. In the present study, we took advantage of a Tn antigen expressing T-lymphocyte clone derived from a patient with the idiopathic form of the Tn syndrome and the Tn+ Jurkat cell line to characterize new reagents that should identify Tn antigens (monoclonal antibody 5F4 and a lectin newly isolated from Moluccella laevis seeds). Flow cytometry revealed that both reagents strongly bound to Tn antigen expressing T lymphocytes but not to normal donor T cells, which are Tn negative. In contrast to mAb 5F4, Moluccella laevis lectin weakly bound to normal donor cells after sialidase pretreatment, indicating its broader specificity. N-Acetyl-D-galactosamine at a concentration of 100 mM significantly reduced antibody binding and abolished lectin binding, completely demonstrating the sugar specificity of both reagents. These reagents should be useful tools in glycobiology and for clinical purposes.
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PMID:Use of O-glycosylation-defective human lymphoid cell lines and flow cytometry to delineate the specificity of Moluccella laevis lectin and monoclonal antibody 5F4 for the Tn antigen (GalNAc alpha 1-O-Ser/Thr). 837 May 96

Glycoconjugates are likely to be of fundamental importance in the complex interactions between photoreceptors and the retinal pigment epithelium, but few have been characterized, especially in human tissue. As a preliminary step towards determining their biological functions in health and disease, a lectin-based histochemical study of the glycan expression of human outer retina was performed on glutaraldehyde-fixed, semi-thin, resin-embedded sections. The interphotoreceptor matrix and photoreceptor plasma-lemmata expressed complex bisected and non-bisected biantennary and/or triantennary N-glycans. In addition, both the rod and cone outer segments bound strongly Galanthus nivalis agglutinin (which binds terminal Man alpha 1, 3Man-) and the rod outer segments bound selectively the isolectin II of Bandeiraea simplicifolia (which binds terminal GlcNAc-). The cilia of the rods and cones were labelled selectively with Glycine max agglutinin after sialidase pretreatment. Four putative glycan outer sequences were identified within the interphotoreceptor matrix: (i) sialylated glycans with subterminal GalNAc alpha 1,3GalNAc-sequences; (ii) a sialylated type with subterminal N-acetyl-lactosamine residues; (iii) Gal beta 1,3GalNAc alpha 1- residues which were substituted with sialic acid except in the cone matrix sheath; (iv) GalNAc alpha 1,6Gal beta 1- residues which were substituted in part with sialic acid. The sialic acid expression throughout was predominantly of the 2,3-linked form with lesser amounts of 2,6-linkage, and rod-associated structures (including the surrounding interphotoreceptor matrix) were labelled more strongly with the sialic acid-binding lectins than cone-associated structures (including the cone matrix sheath).
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PMID:Glycan localization within the human interphotoreceptor matrix and photoreceptor inner and outer segments. 840 May 52


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