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 monosialoganglioside, IV3-NeuNAcLcOse4Cer, has recently been detected in colorectal carcinoma cells, small cell lung carcinoma cells, embryonal carcinoma cells and in human brain extracts. We report here the presence of a CMP-sialic: LcOse4Cer sialyl transferase activity in subcellular membrane fractions of the human colorectal carcinoma. SW1116, which recognizes the non-reducing terminal galactosyl moiety of lactotetraosylceramide. A convenient method for structural analysis of picomolar quantities of the radioactive enzymatic product(s) using bacterial endoglycoceramidase, sialidase and a viral sialidase is presented.
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PMID:Biosynthesis of sialosyllactotetraosylceramide in human colorectal carcinoma cells. 335 Jan 49

Numerous investigations suggest that cell surface glycoconjugates, and in particular sialic acids, are directly involved in determining the metastatic phenotype. To further evaluate this hypothesis, we have used a variety of techniques to probe the cell surfaces of several metastatic variants of the murine B16 melanoma that were selected for experimental lung-colonizing ability (Fidler, I. (1973) Nature 242, 148-149) or for their ability to spontaneously metastasize from the site of a subcutaneous injection (Stackpole, C. W., Alterman, A. L., and Fornabaio, D. M. (1985) Invasion & Metastasis 5, 125-142). Using a highly sensitive high performance liquid chromatography sialic acid assay in conjunction with Vibrio cholerae sialidase, we find that none of these metastatic variants differ significantly in their overall levels of cell surface sialic acid. Using highly purified, linkage-specific sialyltransferases, in conjunction with specific glycosidases, to probe the cell surface saccharide topography of specific penultimate oligosaccharides, we also find no significant differences between the efficient lung-colonizing variant, B16-F10 and the poorly-colonizing B16-F1 or B16-Flr variants. In contrast, the spontaneously metastatic variants examined contain substantially different levels of specific penultimate sialylation sites. The tumorigenic but nonmetastatic B16-LM3/G3.26 variant contains 4-fold more penultimate Gal beta 1-3GalNAc sialylation sites than the tumorigenic and highly metastatic B16-LM3/G3.12 variant when CMP[3H]NeuAc and the alpha 2-3Gal beta 1-3GalNAc sialyltransferase are used to probe the melanoma cell surfaces. Several prominent glycoconjugates of apparent Mr 43,000, 40,000, and 30,000 are especially evident upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the nonmetastatic cells. The nonmetastatic variant also contains 2-fold more Gal beta 1-4GlcNAc sialylation sites than the metastatic variant when the alpha 2-6Gal beta 1-4GlcNAc sialyltransferase is used as a cell surface probe. In this case, glycoconjugates of apparent Mr 74,000, 45,000, and 43,000 are more prominently observed on the cell surfaces of the nonmetastatic variant. These data indicate that the differences in lung-colonizing abilities of B16 melanoma metastatic variants do not correlate with the numbers or sialylation states of specific penultimate oligosaccharide structures on their surfaces. However, the relative levels of specific penultimate saccharide structures do correlate with the ability of the cells to undergo spontaneous metastasis from a subcutaneous tumor.
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PMID:Cell surface sialylation and tumor metastasis. Metastatic potential of B16 melanoma variants correlates with their relative numbers of specific penultimate oligosaccharide structures. 337 1

The activities of ten enzymes involved in sialic acid metabolism were measured in colonic mucosal cells from rats and compared with those in liver. A methodology was devised that enabled all ten enzyme activities to be evaluated in a single rat colon preparation. Enzyme assays with radioactively labelled substrates were developed for maximum sensitivity, and the identification of substrates and products was carefully checked to assess the contribution of contaminants to enzyme reactions with low activity. The activities of most enzymes involved in the biosynthesis of N-acetyl-D-neuraminic acid (NeuAc) from UDP-N-acetyl-D-glucosamine were found to be more than 20-fold lower than those in liver. The activities of CMP-NeuAc synthase, N-acetyl-D-glucosamine 2-epimerase, N-acetyl-D-glucosamine kinase, sialyltransferase and sialidase were similar to or 2-4-fold lower than in liver. The biosynthesis of NeuAc via its 9-phosphate was demonstrated in the 100 000 g supernatant of colonic-cell homogenates by enzymic assay and precursor experiments with N-acetyl[14C]-mannosamine. No alternative route for NeuAc formation could be detected. The 100 000g supernatant fractions of liver, kidney and colonic mucosal cells utilized N-acetyl[14C]mannosamine with differing efficiencies. Radioactive products identified as sialic acid biosynthetic intermediates amounted to 49%, 0.04% and 5.6% of added precursor in liver, kidney and colon respectively. Catabolism of labelled precursor to non-hexosamine products was high in kidney and colonic mucosal-cell fractions.
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PMID:The metabolism of sialic acids in isolated rat colonic mucosal cells. 397 62

Influenza viruses of contrasting receptor specificity have been examined for their ability to infect receptor-modified MDCK cells containing sialyloligosaccharide receptor determinants of defined sequence. Cells were treated with sialidase to remove sialic acid and render them resistant to infection and were then incubated with sialyltransferase and CMP-sialic acid to restore sialic acid in the SA alpha 2,6Gal or SA alpha 2,3Gal linkages. The viruses A/RI/5 + /57 and A/duck/Ukraine/1/63, previously shown to exhibit preferential binding of SA alpha 2,6Gal and SA alpha 2,3Gal linkages, respectively, were found to exhibit differential infection of the receptor-modified cells in accord with their receptor specificity. Coinfection of SA alpha 2,3Gal derivatized cells with a mixture of the two viruses resulted in selective propagation of the SA alpha 2,3Gal-specific A/duck/Ukraine/1/63 virus. The results demonstrate the potential for cell surface receptors to mediate selection of receptor-specific variants of influenza virus.
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PMID:Differential infection of receptor-modified host cells by receptor-specific influenza viruses. 406 Aug 86

Lines of KB cells resistant to Sendai virus-induced cytolysis have been isolated and characterized (Toyama, S., Toyama, Su., and Uetake, H. (1977) Virology 76, 503-515). This study is concerned with the nature of this mutation. Plasma membrane fractions from Sil cells were found to have decreased amount of sialic acid and the same amount of galactose as compared to the membranes from parental KB cells. Sil cells exhibited an increase in sensitivity to toxic effects of ricin and a decrease in sensitivity to wheat germ agglutinin. Binding of wheat germ agglutinin to Sil cells was markedly decreased. Several membrane glycoproteins of Sil cells migrated slightly faster than the corresponding bands of wild type membrane when examined by gel electrophoresis in sodium dodecyl sulfate. Sil cells had decreased sialyltransferase activity that catalyzed the transfer of sialic acid residues from CMP-N-acetylneuraminic acid to glycoprotein acceptors containing Gal beta 1 leads to 3GalNAc alpha 1 leads to O-Ser(Thr) chain. The decreased enzyme activity could not be accounted for by the presence of inhibitors, altered pH optimum, or increased sialidase or CMP-sialic acid hydrolase activities. These results indicate that a molecular basis for the Sil cell phenotype might be the deficiency of sialyltransferase.
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PMID:Deficient cytidine monophospho-N-acetylneuraminic acid: glycoprotein sialyltransferase activity in a clone of KB cells with altered cell fusion ability. 640 1

A sialyltransferase activity present in 7- to 12-day-old embryonic chicken brain catalyzes the transfer of sialic acid from CMP-sialic acid to the terminal galactose residue of [3H]nLcOse4Cer ([3H]Gal(beta 1-4).GlcNAc(beta 1-3)Gal(beta 1-4)Glc-Cer) to form NeuAc(alpha 2-3)-[3H]nLcOse4Cer (LM1 ganglioside). The product is sialidase-labile (96%), and the NeuAc group is linked to O-3 of the terminal galactose residue. The (alpha 2-3) linkage between sialic acid and the terminal galactose was determined on the basis of identification of 2,4,6-tri-O-methyl[3H]galactose obtained after hydrolysis of the permethylated enzymatic product. The CMP-sialic acid:nLcOse4Cer (alpha 2-3)sialyltransferase activity sediments (90%) at the junction of 1.2 M and 1.5 M on a discontinuous sucrose density gradient when still membrane bound (insoluble in 0.2% Triton X-100). The enzyme preparation also catalyzes the transfer of sialic acid from CMP-sialic acid to O-3 of GgOse4Cer (Gal(beta 1-3)GalNAc(beta 1-4)Gal(beta 1-4)Glc-Cer) to form NeuAc (alpha 2-3)GgOse4Cer (GM1b). Substrate inhibition studies indicate that these two reactions are probably catalyzed by the same enzyme.
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PMID:Biosynthesis in vitro of sialyl(alpha 2-3)neolactotetraosylceramide by a sialyltransferase from embryonic chicken brain. 713 Jan 78

Cell surface expressed lactosaminyl glycans were determined on live cells by flow cytometry using a sialyltransferase mediated labeling procedure. Fluorescent CMP-sialic acid and Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase were applied to probe expression of acceptor glycans on untreated or sialidase pretreated erythrocytes. After enzymatic fluorescence labeling, erythrocytes were treated with endo-beta-galactosidase or trypsin to distinguish polylactosaminyl- and complex-type glycans. The expression of lactosaminyl sequences on cord- was 20% lower than on adult cells. After sialidase treatment fluorescence incorporation on both cell types increased twofold compared to untreated cells indicating a low sialylation extent. A recombinant alpha 2,3-sialyltransferase was preferentially labeling polylactosaminyl glycans. Taking advantage of the different fine specificity as determined here, alpha 2,6- and alpha 2,3-sialyltransferase can be applied to distinguish certain types of lactosaminyl glycans.
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PMID:Enzymatic analysis of cell surface lactosaminyl glycans by flow cytometry. 757 5

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

A developmentally regulated trans-sialidase activity is present on the surface of procyclic Trypanosoma brucei. Bloodstream stages display no trans-sialidase activity. T. brucei trans-sialidase is capable of transferring sialic acids from a variety of glycoconjugates into new glycosidic linkages without requirement for CMP-Neu5Ac. The enzyme is linked to the plasma-membrane via a GPI-PLC-resistant GPI-anchor. The comparison of enzymic and structural features of sialidase and trans-sialidase suggests that the two activities may be catalyzed by the same protein, since highly enriched sialidase fractions display trans-sialidase activity. 2-Deoxy-2,3-didehydro-N-acetylneuraminic acid is only a poor inhibitor for the two enzymic activities. Sialic acids are transferred to alpha (2-3)-positions of terminal beta-galactose residues of oligosaccharides and glycoconjugates at various rates. Neu5Ac-alpha(2-3)-lactose is the best trans-sialylation donor tested. Lewis is a poor sialic acid acceptor. T. brucei trans-sialidase utilizes serum glycoconjugates, human and bovine erythrocytes as sialic acid donors, and resialylates sialidase-treated erythrocytes. The enzyme transfers sialic acids from the GPI-anchor of procyclic acidic repetitive protein (PARP) onto lactose and vice versa. Also structures within a variant surface glycoprotein (sVSG MITat. 1.7.) can be trans-sialylated.
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PMID:The developmentally regulated trans-sialidase from Trypanosoma brucei sialylates the procyclic acidic repetitive protein. 825 22

This paper presents a new method for site-specific labelling of antibodies employing enzymatic reactions without oxidizing or reducing agents. IgG was first treated with immobilized sialidase from Clostridium perfringens to cleave bound NeuAc. CMP-9-deoxy-9-salizoyl-NeuAc, an activated sialic acid analogue, was labelled with 131I via the iodogen-method in high yields (> 95%). Then the oligosaccharide chains of antibodies were labelled yield with the radioactive NeuAc analogue by transfer using alpha-2,6-sialyltransferase from rat liver in 50%.
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PMID:Site-specific labelling of the oligosaccharide chains of antibodies. 828 79


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