Enzymes
| UniProtKB help_outline | 20 proteins |
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- Name help_outline a ganglioside GD1b Identifier CHEBI:82939 Charge -2 Formula C52H82N4O39R2 SMILEShelp_outline CC(=O)N[C@@H]1[C@@H](O)C[C@@](O[C@H](CO)[C@@H](O)[C@@H]2O[C@@](C[C@H](O)[C@H]2NC(C)=O)(O[C@@H]2[C@@H](O)[C@H](O[C@H]3[C@H](O)[C@@H](O)[C@H](OC[C@H](NC([*])=O)[C@H](O)[*])O[C@@H]3CO)O[C@H](CO)[C@@H]2O[C@@H]2O[C@H](CO)[C@H](O)[C@H](O[C@@H]3O[C@H](CO)[C@H](O)[C@H](O)[C@H]3O)[C@H]2NC(C)=O)C([O-])=O)(O[C@H]1[C@H](O)[C@H](O)CO)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 16 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,485 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a ganglioside GM1 Identifier CHEBI:82639 Charge -1 Formula C41H66N3O31R2 SMILEShelp_outline CC(=O)N[C@@H]1[C@@H](O)C[C@@](O[C@@H]2[C@@H](O)[C@H](O[C@H]3[C@H](O)[C@@H](O)[C@H](OC[C@H](NC([*])=O)[C@H](O)[*])O[C@@H]3CO)O[C@H](CO)[C@@H]2O[C@@H]2O[C@H](CO)[C@H](O)[C@H](O[C@@H]3O[C@H](CO)[C@H](O)[C@H](O)[C@H]3O)[C@H]2NC(C)=O)(O[C@H]1[C@H](O)[C@H](O)CO)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 23 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline N-acetylneuraminate Identifier CHEBI:35418 Charge -1 Formula C11H18NO9 InChIKeyhelp_outline SQVRNKJHWKZAKO-LUWBGTNYSA-M SMILEShelp_outline [H][C@]1(OC(O)(C[C@H](O)[C@H]1NC(C)=O)C([O-])=O)[C@H](O)[C@H](O)CO 2D coordinates Mol file for the small molecule Search links Involved in 44 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:47876 | RHEA:47877 | RHEA:47878 | RHEA:47879 | |
|---|---|---|---|---|
| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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Selective ganglioside desialylation in the plasma membrane of human neuroblastoma cells.
Kopitz J., von Reitzenstein C., Sinz K., Cantz M.
Gangliosides of the plasma membrane are important modulators of cellular functions. Previous work from our laboratory had suggested that a plasma membrane sialidase was involved in growth control and differentiation in cultured human neuroblastoma cells (SK-N-MC), but its substrates had remained o ... >> More
Gangliosides of the plasma membrane are important modulators of cellular functions. Previous work from our laboratory had suggested that a plasma membrane sialidase was involved in growth control and differentiation in cultured human neuroblastoma cells (SK-N-MC), but its substrates had remained obscure. We now performed sialidase specificity studies in subcellular fractions and found ganglioside GM3 desialylating activity in presence of Triton X-100 to be associated with the plasma membrane, but absent in lysosomes. This Triton-activated plasma membrane enzyme desialylated also gangliosides GD1a, GD1b, and GT1b, thereby forming GM1; cleavage of GM1 and GM2, however, was not observed. Sialidase activity towards the glycoprotein fetuin with modified C-7 sialic acids and towards 4-methylumbelliferyl neuraminate was solely found in lysosomal, but not in plasma membrane fractions. The role of the plasma membrane sialidase in gangliosides desialylation of living cells was examined by following the fate of [3H]galactose-labelled individual gangliosides in pulse-chase experiments in absence and presence of the extracellular sialidase inhibitor 2-deoxy-2,3-dehydro-N-acetylneuraminic acid. When the plasma membrane sialidase was inhibited, radioactivity of all gangliosides chased at the same rate. In the absence of inhibitor, GM3, GD1a, GD1b, GD2, GD3 and GT1b were degraded at a considerably faster rate in confluent cultures, whereas the GM1-pool seemed to be filled by the desialylation of higher gangliosides. The results thus suggest that the plasma membrane sialidase causes selective ganglioside desialylation, and that such surface glycolipid modification triggers growth control and differentiation in human neuroblastoma cells. << Less
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Cloning, expression, and chromosomal mapping of a human ganglioside sialidase.
Wada T., Yoshikawa Y., Tokuyama S., Kuwabara M., Akita H., Miyagi T.
Here we report the cDNA sequence of a human ganglioside sialidase. The cDNA was isolated from a human brain cDNA library by screening with a 240 bp probe generated by polymerase chain reaction using primers based on the sequences of rat cytosolic and bovine membrane sialidases which we previously ... >> More
Here we report the cDNA sequence of a human ganglioside sialidase. The cDNA was isolated from a human brain cDNA library by screening with a 240 bp probe generated by polymerase chain reaction using primers based on the sequences of rat cytosolic and bovine membrane sialidases which we previously cloned. The 3.0 kb cDNA encodes an open reading frame of 436 amino acids containing a putative transmenbrane domain and an Arg-Ile-Pro and three Asp-box sequences characteristic of sialidases and showing overall 83% and 39% identities to the bovine and rat enzymes, respectively. Northern blot analysis revealed high expression in skeletal muscle and testis, but low level in kidney, placenta, lung, and digestive organs. Transient expression of the cDNA in COS-1 cells resulted in a 130-fold increase in sialidase activity compared to the control level, and the activity was found to be almost specific for gangliosides. Fluorescent in situ hybridization allowed the human sialidase gene localized to chromosome 11 at q 13.5. << Less
Biochem. Biophys. Res. Commun. 261:21-27(1999) [PubMed] [EuropePMC]
This publication is cited by 3 other entries.
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Purification and characterization of a membrane-associated ganglioside sialidase from bovine brain.
Hata K., Wada T., Hasegawa A., Kiso M., Miyagi T.
A membrane-associated ganglioside-hydrolyzing sialidase was purified to apparent homogeneity from bovine brain. The enzyme was solubilized with Triton X-100 plus sodium cholate from the particulate fraction and purified over 100,000-fold by sequential chromatography on DEAE-cellulose, octyl-Sephar ... >> More
A membrane-associated ganglioside-hydrolyzing sialidase was purified to apparent homogeneity from bovine brain. The enzyme was solubilized with Triton X-100 plus sodium cholate from the particulate fraction and purified over 100,000-fold by sequential chromatography on DEAE-cellulose, octyl-Sepharose, heparin-Sepharose, Sephacryl S-200, MonoQ, RCA-agarose, thiol-activated Sepharose, and ganglioside-affinity Sepharose. The final enzyme preparation exhibited a specific activity of 4,851.3 micromol/h/mg protein and an apparent molecular mass of 52 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme preferentially hydrolyzed gangliosides other than GM1 and GM2 but demonstrated hardly any activity against glycoproteins and oligosaccharides. Gangliosides GD3, GD1a, and GT1b were much better substrates than GM3 and GD1b in the presence of Triton X-100, but the latter became more sensitive to the sialidase with addition of sodium cholate. The enzyme was activated by dithiothreitol, strongly inhibited by 4-hydroxy-mercuribenzoate, and firmly adsorbed to thiol-activated Sepharose, indicating that free sulfhydryl groups are essential for its catalytic activity. Subcellular fractionation experiments revealed that the enzyme is mainly located in the synaptosomal fraction. << Less
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Properties of recombinant human cytosolic sialidase HsNEU2. The enzyme hydrolyzes monomerically dispersed GM1 ganglioside molecules.
Tringali C., Papini N., Fusi P., Croci G., Borsani G., Preti A., Tortora P., Tettamanti G., Venerando B., Monti E.
Recombinant human cytosolic sialidase (HsNEU2), expressed in Escherichia coli, was purified to homogeneity, and its substrate specificity was studied. HsNEU2 hydrolyzed 4-methylumbelliferyl alpha-NeuAc, alpha 2-->3 sialyllactose, glycoproteins (fetuin, alpha-acid glycoprotein, transferrin, and bov ... >> More
Recombinant human cytosolic sialidase (HsNEU2), expressed in Escherichia coli, was purified to homogeneity, and its substrate specificity was studied. HsNEU2 hydrolyzed 4-methylumbelliferyl alpha-NeuAc, alpha 2-->3 sialyllactose, glycoproteins (fetuin, alpha-acid glycoprotein, transferrin, and bovine submaxillary gland mucin), micellar gangliosides GD1a, GD1b, GT1b, and alpha 2-->3 paragloboside, and vesicular GM3. alpha 2-->6 sialyllactose, colominic acid, GM1 oligosaccharide, whereas micellar GM2 and GM1 were resistant. The optimal pH was 5.6, kinetics Michaelis-Menten type, V(max) varying from 250 IU/mg protein (GD1a) to 0.7 IU/mg protein (alpha(1)-acid glycoprotein), and K(m) in the millimolar range. HsNEU2 was activated by detergents (Triton X-100) only with gangliosidic substrates; the change of GM3 from vesicular to mixed micellar aggregation led to a 8.5-fold V(max) increase. HsNEU2 acted on gangliosides (GD1a, GM1, and GM2) at nanomolar concentrations. With these dispersions (studied in detailed on GM1), where monomers are bound to the tube wall or dilutedly associated (1:2000, mol/mol) to Triton X-100 micelles, the V(max) values were 25 and 72 microIU/mg protein, and K(m) was 10 and 15 x 10(-9) m, respectively. Remarkably, GM1 and GM2 were recognized only as monomers. HsNEU2 worked at pH 7.0 with an efficiency (compared with that at pH 5.6) ranging from 4% (on GD1a) to 64% (on alpha(1)-acid glycoprotein), from 7% (on GD1a) to 45% (on GM3) in the presence of Triton X-100, and from 30 to 40% on GM1 monomeric dispersion. These results show that HsNEU2 differentially recognizes the type of sialosyl linkage, the aglycone part of the substrate, and the supramolecular organization (monomer/micelle/vesicle) of gangliosides. The last ability might be relevant in sialidase interactions with gangliosides under physiological conditions. << Less
J. Biol. Chem. 279:3169-3179(2004) [PubMed] [EuropePMC]
This publication is cited by 5 other entries.