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)

The activity of neuraminidase (sialidase) in peripheral white blood cells was measured by a fluorometric method using 4-MU NANA as a substrate. The activity in mononuclear cells, which was predominantly lymphocytes, was 2.5 times higher than that in polymorphonuclear cells (neutrophils). The former's activity was directly proportional to the number of the cells, but that of the latter was found to be suppressed by an increasing number of cells. Thus, the increased number of PMN contaminated in MNC fraction somewhat obscured neuraminidase activity affecting suppressively . The enzyme activity in MNC of 25 control subjects (15 males and 10 females) was 254 +/- 73 pmoles per hour per 10(6) cells and there was no difference between the values in males and females (233 +/- 59 vs. 284 +/- 81). The activity in 20 patients with chronic active liver disease was significantly higher than that in controls (551 +/- 135, p less than 0.01). The amount of sialic acid in MNC, which was 1.4 times more than that in PMN, revealed a tendency for a positive correlation between neuraminidase activity. A new finding of the increase of lymphocyte neuraminidase activity was introduced and its pathological significance particularly in liver disease was discussed.
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PMID:Neuraminidase activity in human peripheral lymphocytes: its increase in chronic active liver disease. 672 57

Sialidase activity associated with rat brain synaptic junctions (SJ) and synaptic membranes (SM) was determined. Both fractions released sialic acid from exogenous glycopeptides and gangliosides. SJ accounted for 5-10% of the total sialidase activity recovered from SM following extraction with Triton X-100, and the specific activity of SJ sialidase was 60% of that of the parent SM fraction. Intrinsic SJ sialidase hydrolysed 12-15% of the sialic acid associated with endogenous SJ glycoproteins. Sialic acid residues associated with SJ glycoproteins were labelled with sodium borotritide and SJ proteins fractionated by affinity chromatography on concanavalin A-agarose. SJ glycoproteins that reacted with concanavalin A (con A+ glycoproteins) accounted for 25% of the total SJ [3H]sialic acid. Intrinsic SJ sialidase hydrolysed 20% of the [3H]sialic acid associated with these glycoproteins. Each molecular weight class of con A+ glycoprotein previously shown to be a specific component of the postsynaptic apparatus contained sialic acid and was acted on by intrinsic SJ sialidase.
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PMID:Identification of intrinsic sialidase and sialoglycoprotein substrates in rat brain synaptic junctions. 685 22

1. The action of sialidases from Newcastle disease virus (NDV), influenza A2 virus (IA2V) and fowl plague virus (FPV) on sialyloligosaccharide substrates containing alpha 2-3, alpha 2-6 or alpha 2-8 linkages was studied. 2. In all cases 2-3-linked sialic acids were preferentially released. Compared with II6Neu5AcLac, all 2-6-linked substrates, including sialyl-N-acetyllactosamine and its asparaginyl derivative, a urinary hexasaccharide and Neu5Ac(2-6)GalNAc were cleaved at improved rates by NDV and less by FPV sialidases. In the case of IA2V sialidase the asparaginyl oligosaccharide was very poorly cleaved, illustrating a variation in viral strain specificity. 3. A decrease in relative rates was observed in the order NDV greater than IA2V greater than FPV for substrates with 2-3 linkages relative to II6Neu5AcLac. The greatest relative rate was 470-fold higher. The 2-3-linked sialyl-N-acetyllactosaminylasparagine and IV3Neu5AcLcOse4 were poor substrates for the IA2V sialidase, but the rates were greater than with the 2-6 linked substrates. 4. The ganglioside substrate II3Neu5AcLacCer showed lower activity than its oligosaccharide analogue, but neither II3Neu5AcGgOse4Cer nor its oligosaccharide were substrates. 5. The Km values for 2-6-linked substrates were generally of the order 10 mM while those for the 2-3-linked substrates were approximately 1 mM. The V values were consistently higher for the 2-3-linked substrates. IV3Neu5AcLcOse4 showed high Km and very high V values, while the 2-8-linked disialyllactose showed this trend only with NDV enzyme, the IA2V and FPV sialidases exhibiting high Km and low V values. 6. The results are discussed in the light of the current knowledge of viral sialidase specificity and relative to the binding of virus particles to cell surfaces.
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PMID:The specificity of viral sialidases. The use of oligosaccharide substrates to probe enzymic characteristics and strain-specific differences. 710 4

Gangliosides were isolated from rat liver and erythrocytes by chromatography on columns of DEAE-Sephadex and Iatrobeads, and finally purified by preparative TLC. The chemical structures of the purified components were studied by carbohydrate analysis, methylation analysis, sialidase treatment, fatty acid analysis and direct mass spectrometry. In rat liver, gangliosides GM3, GM1, GD3, GD1a, GD1b, and GT1b were identified. Gangliosides in rat erythrocytes were characterized as GM1, fucosyl-GM1, and GD1a. Sialic acid was the N-acetyl type only and lignoceric acid was the main fatty acid in all components of rat liver and erythrocytes.
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PMID:Structural study on gangliosides from rat liver and erythrocytes. 715 12

Bacteroides fragilis SBT3182 produced two sialidases which differ in molecular weight on SDS-PAGE. These sialidases, a 50 kDa and a 55 kDa enzymes, were purified separately and their properties were compared. Both enzymes preferentially hydrolyze sialyl alpha 2-8 linkage rather than alpha 2-3 and alpha 2-6 bonds. The Km values for Neu5Ac alpha 2-3lactose, Neu5Ac alpha 2-6lactose, and colominic acid, which is a homopolymer of N-acetylneuraminic acid linked by alpha 2-8 bonds, were identical between the two enzymes. These enzymes had Km value of 1.0-1.2 mM for Neu5Ac alpha 2-3lactose and 1.3-1.5 mM for Neu5Ac alpha 2-6lactose, which are in the ranges reported for other sialidases. However, the Km values for colominic acid (0.03-0.04 mM) were lower than those of other sialidases, indicating that sialidases from B. fragilis SBT3182 show high affinity for the sialyl alpha 2-8 linkage. The two sialidases also had identical N-terminal amino acid sequences and did not reveal any homology to known sialidases. PAS-staining suggested that these two sialidases were glycoproteins. In the lectin analysis, the 50 kDa enzyme was stained with Con A, DBA, and UEA-I while the 55 kDa sialidase was stained only with Con A. This suggested that the difference in molecular weight may be due to the carbohydrate composition. When the 50 kDa enzyme was incubated with UEA-I, which is a lectin specific for alpha-fucose residue, the activity decreased by 20%.
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PMID:Two sialidases which preferentially hydrolyze sialyl alpha 2-8 linkage from Bacteroides fragilis SBT3182. 751 73

The effect of substrate aglycon on enzyme mechanism of sialidase from influenza virus was investigated by kinetic isotope effects using the substrates 4-methylumbelliferyl-N-acetyl-alpha-D-neuraminic acid (Neu5Ac alpha 2MU) and p-nitrophenyl-N-acetyl-alpha-D-neuraminic acid (Neu5Ac alpha 2PNP). The kinetic isotope effect on Vmax (beta DV), at pH 6.0, as revealed by direct comparison of rates obtained with Neu5Ac alpha 2MU and the [3,3-2H]-substituted substrate analogue, was shown to be inverse. This indicates that sialidase-catalysed hydrolysis of Neu5Ac alpha 2MU proceeds with substantial positive charge development at the reaction centre in the transition state for the formation of the glycosyl cation-enzyme intermediate. However, no such inverse effect on Vmax at pH 6.0 was observed when using Neu5Ac alpha 2PNP and the [3,3-2H]-substituted substrate. A mechanism by which hydrolysis proceeds through an alpha-lactone intermediate has been proposed by Guo et al. [8]. We propose that the differences in beta DV for the substrates investigated are due primarily to the differing properties of the aglycon leaving groups, which may result in influenza virus sialidase catalysing substrate hydrolysis by a similar mechanism with alternative stabilisation of transition state.
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PMID:Effect of substrate aglycon on enzyme mechanism in the reaction of sialidase from influenza virus. 755 57

The sialidase of swine influenza A viruses of N1 and N2 subtypes, isolated from 1930 to 1992, was studied for substrate specificity with ganglio-series, lacto-series type II and GM3 gangliosides containing Neu5Ac alpha 2-3Gal, Neu5Gc alpha 2-3Gal and Neu5Ac alpha 2-6Gal linkages. All viral sialidases tested showed that the activity for hydrolysing substrates with Neu5Ac alpha 2-3Gal was higher than the activities with Neu5Gc alpha 2-3Gal and Neu5Ac alpha 2-6Gal linkages. When GM1b, GM3 and sialylparagloboside were used as substrates, the earliest strain (A/Wisconsin/15/30 H1N1, isolated in 1930) showed the activity ratio of Neu5Ac alpha 2-6Gal to Neu5Ac alpha 2-3Gal to be 0.13:0.2, and the ratio Neu5Gc alpha 2-3Gal/Neu5Ac alpha 2-3Gal to be 0.19:0.37, while those strains isolated from 1978 to 1992 exhibited ratios of 0.29:0.58 for Neu5Ac alpha 2-6Gal/Neu5Ac alpha 2-3Gal and 0.51:0.76 for Neu5Gc alpha 2-3Gal/Neu5Ac alpha 2-3Gal. The above results indicate that the substrate specificities of sialidases from swine influenza A viruses towards sialyl linkages and the molecular species of sialic acid are related to the year of isolation, i.e. strains isolated after 1978 exhibited higher activity towards Neu5Ac alpha 2-6Gal and Neu5Gc alpha 2-3Gal linkages when compared with strains isolated in an earlier year, 1930.
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PMID:Sialidase of swine influenza A viruses: variation of the recognition specificities for sialyl linkages and for the molecular species of sialic acid with the year of isolation. 762 Mar 33

CD36 is a glycoprotein included in the bovine milk fat globule membrane derived from mammary secretory epithelial cells during lactation. Asparagine-linked sugar chains were quantitatively released from CD36 as oligosaccharides by hydrazinolysis. These sugar chains were converted to radioactive oligosaccharides by reduction with NaB3H4 and separated into neutral and acidic fractions by paper electrophoresis. Most of the acidic oligosaccharides were converted to neutral ones by sialidase digestion, indicating that they are sialyl derivatives. The neutral and sialidase-treated acidic oligosaccharides were fractionated by Bio-Gel P-4 column chromatography in combination with serial chromatography on immobilized lectin columns including a Wistaria floribunda agglutinin (WFA)-agarose column. WFA is known to bind oligosaccharides terminating with either an alpha- or beta-N-acetylgalactosamine residue. Structural studies of oligosaccharides in each fraction by sequential exoglycosidase digestion as well as methylation analysis revealed that CD36 contains high mannose-type, hybrid-type, and bi, tri-, and tetraantennary complex-type sugar chains. A portion of the hybrid-type and the complex-type sugar chains which bound to a WFA-agarose column (28% of all oligosaccharides) contained the GalNAc beta 1-->4GlcNAc group(s) instead of the Gal beta 1-->4GlcNAc group(s) in their outer chain moieties. Like oligosaccharides found in human luteinizing hormone [Weisshaar, G., Hiyama, J., Renwick, A. G., & Nimtz, M. (1991) Eur. J. Biochem. 195, 257-268], some of the GalNAc beta 1-->4GlcNAc groups found in the CD36 oligosaccharides were sialylated as the Neu5Ac alpha 2-->6GalNAc group. Furthermore, most of the hybrid-type sugar chains of CD36 with the Gal/GalNAc beta 1-->4GlcNAc beta 1-->2 outer chain on their Man alpha 1-->3 arm contained an unusual Man alpha 1-->2Man alpha 1-->3 group on their Man alpha 1-->6 arm.
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PMID:Structural study of the sugar chains of CD36 purified from bovine mammary epithelial cells: occurrence of novel hybrid-type sugar chains containing the Neu5Ac alpha 2-->6GalNAc beta 1-->4GlcNAc and the Man alpha 1-->2Man alpha 1-->3Man alpha 1-->6Man groups. 768 47

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

We have investigated sialidase activities in transformed rat 3Y1 cells of different metastatic potential. Only lysosome-type sialidase was apparent in the particulate fractions of 3Y1 cells and their transformants. As compared with control 3Y1 cells, src-transformed cells exhibited decreased sialidase activity, and v-fos transfer to these latter induced even more severe decrease in the sialidase activity with acquisition of high lung metastatic ability. Various lysosomal enzymes other than sialidase were hardly affected by the transformation. Sialic acid transfer to N-linked glycoproteins was slightly elevated in the transformants, but not in parallel with their metastatic potential.
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PMID:Metastatic potential of transformed rat 3Y1 cell lines is inversely correlated with lysosomal-type sialidase activity. 805 May 77


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