Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cholesterol was identified as an essential component of the receptor on the sheep erythrocyte to which Rickettsia prowazeki adsorbs before lysing the cell. Erythrocytes or ghosts, derived by hypotonic lysis, were treated with proteolytic enzymes, sialidase, sulfhydryl reagents, and periodate without affecting their ability to adsorb rickettsiae. Lipid extracts of ghosts and erythrocytes, on the other hand, contained receptor activity. Fractionation of the lipid extracts by silicic acid column chromatogrphy resulted in the isolation of receptor activity in a neutral lipid fraction. The lipid fractions demonstrated receptor acitity at 34 C but not at 0 C. These properties are also characteristic of the receptor activity with erythrocytes and ghosts. Cholesterol, co-lyophilized with palmitic acid, was found to possess receptor activity. Palmitic acid alone, cholesterol-lecithin, cholestane-palmitic acid, and various phospholipids and glycolipids had no receptor activity. Ghosts treated with amphotericin B or digitonin, compounds that bind to cholesterol in the membrane, lost their ability to adsorb rickettsiae.
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PMID:Identification of cholesterol in the receptor site for rickettsiae on sheep erythrocyte membranes. 17 13

Two gangliosides, representing 85% of total lipid-bound sialic acid, have been isolated from bovine buttermilk and characterized. Both contained long-chain base, glucose, galactose and sialic acid in the molar ratio 1:1:1:2, and gave, upon sialidase treatment, a neutral glycolipid, characterized as lactosylceramide. Partial acid hydrolysis, permethylation analysis and chromium trioxide oxidation indicated their basic oligosaccharide portion to be NeuAc alpha 2----8NeuAc alpha 2----3Gal beta 1----4Glc. The difference between the two forms was exclusively in the ceramide moiety of the molecule, one containing mainly long-chain (C22-C25) fatty acids and an equimolar proportion of C16 and C18 long-chain bases, and the other mainly palmitic acid and C18 long-chain base.
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PMID:Characterization of two molecular species GD3 ganglioside from bovine buttermilk. 397 Sep 56

Ganglio-N-triaosylceramide (GalNAc beta 1 leads to 4Gal beta 1 leads to 4Glc beta 1 leads to 1Cer), a tumor-associated marker for L5178 cells, was previously reported to separate on thin layer chromatography into three distinct bands (bands a, b, and c). The present paper describes the characterization of these bands and the factor that determines the degree of glycolipid exposure at the cell surface and its antigenicity. 1) The resolution of ganglio-N-triaosylceramide into three bands was found to be due to molecules having different fatty acid compositions. Band a contained nervonic (C24:1) and lignoceric (C24:0) acids, band b contained palmitic acid (C16:0), and band c contained alpha-hydroxypalmitic acid. 2) Surface labeling of L5178c127 cells with galactose oxidase/sodium borotritide, followed by fluorography of the isolated glycolipids, revealed that all three bands were exposed on the surface of the cell. However, treatment of cells with sialidase before treatment with galactose oxidase resulted in a 10-fold increase of label incorporated into ganglio-N-triaosylceramide. Since no sialylated form of ganglio-N-triaosylceramide was detected on these cells, and no change in the chemical amount of this glycolipid could be detected, the increase of label into this molecule was due to the exposure by sialidase of a normally cryptic glycolipid. The exposure of ganglio-N-triaosylceramide after sialidase treatment was also reflected by the increased sensitivity of these cells to monoclonal antibodies to the glycolipid and complement after enzyme treatment. Thus, the results provide clear evidence that crypticity, as well as antigenicity, of a membrane glycolipid is determined by the degree of sialylation in a second membrane glycoconjugate.
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PMID:Characterization of tumor-associated ganglio-N-triaosylceramide in mouse lymphoma and the dependency of its exposure and antigenicity on the sialosyl residues of a second glycoconjugate. 618 30

The trans-sialidase from the trypomastigote stage of Trypanosoma cruzi was metabolically labeled with [3H]-palmitic acid and purified by immunoprecipitation with a monoclonal antibody. The action of PI-PLC on the immunoprecipitate released a lipid that was analyzed by TLC. Lyso-1-O-hexadecylglycerol and N-palmitoyl-sphinganine were obtained in a 1:3 ratio. A comparison with the GPI anchors present in the different stages of T. cruzi was made.
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PMID:The trans-sialidase of Trypanosoma cruzi is anchored by two different lipids. 937 75

Both, culture-derived and metacyclic trypomastigotes of Trypanosoma cruzi shed a glycoprotein, the shed acute phase antigen, that is responsible for the trans-sialidase activity. In the present work the structure of the glycosylphosphatidylinositol membrane anchor of the trans-sialidase isolated from metacyclic forms was determined. Parasites were metabolically labelled with [9, 10(n)3H]-palmitic acid and the glycoprotein was purified by immunoprecipitation with a monoclonal antibody directed against the repetitive aminoacid sequence. Treatment of the glycoprotein with phosphatidylinositol phospholipase C (PI-PLC) from Bacillus thuringiensis rendered a lipid that comigrated in TLC with a standard of ceramide. No alkylglycerol was detected in contrast with the results previously obtained for the trans-sialidase isolated from culture-derived trypomastigotes where both lipids were found. Chemical and chromatographic analysis showed that the lipid moiety is palmitoyldihydrosphingosine with a minor amount of stearoyldihydrosphingosine. The glycan constituent of the glycosylphosphatidylinositol-anchor was analysed by nitrous acid deamination of the aqueous phase of the PI-PLC treatment, followed by reduction with NaBH4 and hydrolysis of the phosphodiester with aqueous hydrofluoric acid. A major oligosaccharide was obtained and enzymatic treatment with exoglycosidases and further chromatography in a high pH anion exchange system showed that the trimannosyl core backbone is substituted by an alpha-galactose. A comparison between the lipid constituent of the glycosylphosphatidylinositol anchor of several proteins and their spontaneous shedding by the action of an endogenous PI-PLC was made.
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PMID:Structure of the glycosylphosphatidylinositol-anchor of the trans-sialidase from Trypanosoma cruzi metacyclic trypomastigote forms. 987 92