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)

We have demonstrated that rat liver contains at least four types of sialidase differing in subcellular location, in catalytic property and immunologically. They are intralysosomal, cytosolic and membrane-associated sialidases I and II. Membrane sialidase I locates mainly in plasma membrane and sialidase II in lysosomal membrane. Immunological study reveals that the same types of sialidase exist in various tissues of rat and of other mammalian species. Based on these results, we examined the sialidases in rat hepatomas and in transformed cells of JB6 mouse epidermal cell. Hepatomas were found to possess four types of sialidase and the three of them altered quantitatively. Intralysosomal sialidase activity was higher but cytosolic and lysosomal membrane sialidase activities were lower in hepatomas than in control liver. When the sialidases of transformants of JB6 cells were compared with those of control cells, the activities of two lysosomal sialidases were decreased and contrarily plasma membrane sialidase was increased. We discussed a possible significance of the sialidase alterations in carcinogenesis.
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PMID:Multiple forms of mammalian sialidase: altered expression in carcinogenesis. 130 7

Rat kidney sialidase levels have been reported to be markedly altered in pathological states such as diabetes. This was associated with a modification of sialic acid levels. Therefore, it was interesting to study the variations of kidney sialidase and sialyltransferase activities and sialic acid content according to sex and age. This was carried out from birth to 210 days of age. The substrates used were sialyl alpha(2-3)[3H]-lactitol for sialidase activity, asialofetuin and [14C]-CMPNeu5Ac for sialyltransferase activity. In males sialidase activity increased until 32 days then slightly declined. In females, the activity increased and leveled off at 135 days of age. Higher sialidase activity was observed in females than in males from 56 days of age. Gonadectomy had no effect on this activity. In both sexes, sialyltransferase activity decreased markedly with age. This activity was higher in females than in males, whereas sialic acid levels varied only moderately with age and were slightly higher in females.
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PMID:Sex and age dependence of rat kidney sialidase. 130 56

A sialidase from Bacteroides fragilis SBT3182 was purified 2,240-fold to apparent homogeneity by ammonium sulfate precipitation and sequential chromatographies on DEAE-Toyopearl 650M, Hydroxyapatite, MonoS and Superose6 columns. The N-terminal amino acid sequence of this sialidase, Ala-Asp-X-Ile-Phe-Val-Arg-Glu-Thr-Arg-Ile-Pro-, was determined. Substrate specificity of this enzyme using a variety of sialoglycoconjugates showed a 1.5- and 2.2-fold preference for sialyl alpha 2-8 linkages when compared with alpha 2-3 and alpha 2-6 bound sialic acids, respectively. The native sialidase had a molecular weight of 165kDa, as determined by Superose6 gel filtration chromatography and consisted of three subunits each of 55kDa by SDS-polyacrylamide gel electrophoresis. This enzyme had optimal activity at pH6.1 with colominic acid as substrate.
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PMID:Purification and characterization of a sialidase from Bacteroides fragilis SBT3182. 133 98

Sialidase treatment of rat thrombocytes led to an increased binding of these cells to homologous peritoneal macrophages, but had no significant effect on the rate of phagocytosis during the experimental time. As revealed by electron microscopy, the partially desialylated thrombocytes adhere to macrophages predominantly via a small part of the membrane in a way that the discoidal cells adopt a vertical position with regard to the macrophage surface. One adherent macrophage was able to bind up to 55 sialidase-treated thrombocytes. Maximum binding was already reached after release of 13% of sialic acids. This interaction could be inhibited by free D-galactose and compounds with terminal D-galactose residues. Bound thrombocytes were released from the macrophages by treatment with lactose or EDTA. These experiments suggest that the interaction is mediated by a galactose-specific receptor on the macrophage surface and that galactose on thrombocytes is not recognized if it is masked by terminal sialic acid residues. The total sialic acid amount of the thrombocytes studied was about 70 micrograms sialic acid/10(10) cells being composed of 78% N-glycoloylneuraminic acid, 17% N-acetylneuraminic acid and 5% of the novel sialic acid N-(O-acetyl)glycoloylneuraminic acid, which was identified by mass spectrometry. Sixty-two percent of these sialic acids were susceptible to enzymic hydrolysis with Vibrio cholerae sialidase.
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PMID:Interaction of rat peritoneal macrophages with homologous sialidase-treated thrombocytes in vitro: biochemical and morphological studies. Detection of N-(O-acetyl)glycoloylneuraminic acid. 133 32

The significance of glycoconjugates on the surface of rat erythrocytes was studied in the interaction of these cells with homologous peritoneal macrophages. The erythrocytes exposing terminal alpha-galactose and thus of B blood group specificity, as well as sialic acid are not bound by the macrophages. beta-Galactose residues exposed by sialidase induced strong binding and additional alpha-galactosidase treatment enhanced the binding. beta-Galactose exposed on glycolipids after pronase and alpha-galactosidase treatment induced no binding. An intact protein core of the glycoproteins on the erythrocyte surface was necessary for interaction with macrophages. Partial de-O-acetylation of sialic acids prior to sialidase treatment stimulated subsequent binding of the erythrocytes.
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PMID:The influence of alpha- and beta-galactose residues and sialic acid O-acetyl groups of rat erythrocytes on the interaction with peritoneal macrophages. 133 29

The cDNA coding for pre-peanut agglutinin (PNA) was isolated from a bacterial expression library. It codes for a polypeptide of 273 amino acids composed of a hydrophobic signal peptide of 23 amino acids and a mature protein of 250 amino acids. The sequence of the latter is identical to that of native PNA, determined very recently by conventional methods, except that it contains 14 additional amino acids at the C-terminus. Bacterial cells harboring a plasmid with the prePNA-cDNA, produced two PNA cross-reacting proteins: one migrated on SDS-PAGE identically with the native lectin (apparent mol. wt. 31 kDa); the other, at 35 kDa, was a beta-galactosidase pre-PNA fusion protein. The former protein possessed an N-terminal sequence identical to that of the mature, native PNA, suggesting that it was processed from the 35 kDa prePNA precursor. Only the 31 kDa protein was exported into the bacterial periplasmic space, and had the ability to bind to galactose-Sepharose. The isolated processed protein had the same hemagglutinating activity as the native lectin, when assayed with sialidase-treated human erythrocytes. Like the native lectin, it did not agglutinate the untreated cells, was not inhibited by N-acetylgalactosamine, and was inhibited by Gal beta 1----3GalNAc 30-times more strongly than by galactose.
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PMID:Cloning, sequence analysis and expression in Escherichia coli of the cDNA encoding a precursor of peanut agglutinin. 133 58

Five monoclonal antibodies (moABs TKH-2, MA54, MA61, B72.3, and CC49), directed toward the O-linked mucin-type glycoprotein, showed signs of specific reactivity with human meconium. The reactivity of these moABs with meconium extract was examined by solid-phase ELISA with different native and sialidase-treated glycoproteins. All moABs react with meconium extract, whereas the reactivities of TKH-2, MA54, and MA61 are sialidase sensitive and the reactivity of TKH-2 with meconium extract was only inhibited by ovine submaxillary mucin (OSM), indicating that TKH-2 is the most sensitive and specific antibody clearly directed to the sialyl Tn antigen in meconium. The possible application of TKH-2 to diagnose amniotic fluid embolism (AFE) has been prelimiarily investigated. We demonstrated that the concentration of sialyl Tn antigen in the serum of patients with AFE was significantly increased, indicating that meconium was released into the maternal circulation. Our method for detecting sialyl Tn antigen in the serum of AFE patients is a direct way to demonstrate the release of meconium into the maternal circulation, and is a simple, rapid, non-invasive and sensitive method for the diagnosis of AFE.
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PMID:[A new method for diagnosis of amniotic fluid embolism by means of monoclonal antibody TKH-2 that recognizes mucin-type glycoprotein, a component in meconium]. 135 39

Cell-surface oligosaccharides can function as ligands for intercellular adhesion receptors, matrix proteins, and growth factors. We report that human neonatal and adult epidermal keratinocytes (KC) express sialyl Lewis X [s-Le(x); SA alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3R], a ligand for endothelial and platelet selectins. Freshly isolated or cultured KC bind FH6 monoclonal antibody (MoAb), which is specific for s-Le(x)-containing oligosaccharides. The relevant epitope is bona fide s-Le(x), because sialidase treatment of KC suspensions abrogates FH6 binding while generating de novo KC reactivity with anti-Le(x). KC stained in ice-cold suspension display a knobby membrane distribution of s-Le(x) detectable by immunofluorescence microscopy. As others have reported, FH6 appeared not to bind KC in perpendicular skin sections. However, basal KC in intact epidermal sheets exhibited obvious "honeycomb" reactivity with FH6 when stained and viewed en face, suggesting that s-Le(x) in intact epidermis may occur in bands that parallel the major tissue axis. FH6 specifically immunoprecipitated proteins of Mr 34 kd, 44 kd, and 56 kd from [35S]-labeled KC, and anti-Le(x) precipitated similar proteins from sialidase-treated KC. The enzymatic basis for KC s-Le(x) expression was studied by analyzing acceptor specificities and other properties of KC fucosyltransferases. Results indicate that KC express both Lewis- and myeloid-type alpha 1-3fucosyltransferases. KC s-Le(x) could be an important element of the epithelial milieu, because both epithelial cells and immune cells that home to epithelia express s-Le(x) and related structures, and because KC s-Le(x) is well positioned for selectin-mediated platelet binding after trans-cutaneous wounding. The apparent distributions of s-Le(x) in epidermis and on isolated KC are compatible with a functional role for s-Le(x) in these intercellular interactions.
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PMID:Human epidermal keratinocyte expression of sialyl-Lewis X. 135 80

Equinatoxins were purified from the tentacles and bodies of the sea anemone Actinia equina by the use of acetone precipitation, as well as column chromatographies on Sephadex G-50 and CM-cellulose according to the modified method of Macek and Lebez (1988). The equinatoxins obtained, equinatoxin 1 and 2, were hemolytic glycoproteins with a relative molecular mass of 20000. Equinatoxin 2 was found to be rich in glycine, alanine and valine. The amino acid sequences of equinatoxins 1 and 2 were partially determined. A portion of the N-terminal amino acid sequence of equinatoxin 2 was similar to those of pyruvate kinase and sialidase.
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PMID:Isolation and characterization of equinatoxins from the sea anemone Actinia equina L. 136 Nov 61

Trypanosoma cruzi invades a variety of mammalian cells by receptor-ligand interactions. In this review two T. cruzi carbohydrate-binding proteins, neuraminidase/trans-sialidase and penetrin, are discussed as possibly playing a role in parasite entry into mammalian cells.
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PMID:Entry of Trypanosoma cruzi into eukaryotic cells. 136 37


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