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)

Chickens were exposed to SO2 in relatively low concentrations (3.4 to 18.5 parts per million (ppm)) for 1 to 14 days. A portion of their tracheas was embedded in water-soluble methacrylate, cut at 2 micrometer and stained with hematoxylin and eosin, Wright's stain, methyl green-pyronin, Alcian blue - periodic and Schiff, and for acid phosphatase. An increase was found in (a) the mucosa to wall ratio; (b) the number of mucosal cells in mitosis; (c) the number of macrophages, lymphocytes, plasma cells, and neutrophils in the epithelium and lamina propria; and (d) the number of these infiltrating cells which contained acid phosphatase. The number of mucus- and seromucus- secreting cells and vasoamine-containing cells were sometimes increased, but not consistently. The percentage of cells containing sialidase-sensitive sialomucins was elevated, and percentage of cells containing neutral mucins was reduced. These changes were only partly related to the SO2 concentration and the duration of SO2 exposure, in that increasing amounts of SO2 did not always cause increasing changes in the mucin composition. Evidently, the altered mucins sometimes protected against further mucin modification.
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PMID:Quantitative histological changes produced in the tracheal mucosa of young chickens by the inhalation of sulfur dioxide in low concentrations. 55 68

The gene(s) encoding the Trypanosoma cruzi shed-acute-phase-antigen (SAPA) has a 5' end encoding a region containing two totally and two partially conserved Ser-X-Asp-X-Gly-X-Thr-Trp motifs which are present in bacterial neuraminidases, and a 3' end encoding tandemly repeated units of 12 amino acids. It is now reported that 54-87% of the total neuraminidase activity present in the parasite could be immunoprecipitated with polyclonal or monoclonal antibodies against the repeated amino acid units of SAPA. These immunoprecipitates also had greater than 80% of the trans-sialidase activity of the parasite. SAPA used sialyllactose, fetuin and 4-methylumbelliferyl-sialic acid as substrate donors. In the presence of a suitable acceptor molecule (lactose) the sialic acid residues were transferred to the disaccharide, whereas in the absence of acceptors the residues were transferred to water. If relatively inefficient acceptors (maltose or cellobiose) were added to the incubation mixtures, the sialic acid units were transferred both to the disaccharides and to water. It is concluded that a major T. cruzi antigen has both the trans-sialidase and the neuraminidase activities of the parasite. Both activities are probably located on the N-terminus of SAPA since antibodies directed against the C-terminus, which contains the repeated amino acid units, do not affect the enzymatic activities.
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PMID:Identification of the gene(s) coding for the trans-sialidase of Trypanosoma cruzi. 137 11

We investigated the effect of maternal alcohol consumption on cell number, gangliosides and ganglioside catabolizing enzymes in the central nervous system (CNS) of the offspring. Virgin female rats of the Charles Foster strain were given 15% (v/v) ethanol in drinking water one month prior to conception and during gestation and lactation. At 21 days postnatal age, the offspring were sacrificed and the brains were separated into cerebrum, cerebellum and brain stem to investigate possible regional variations. Compared to controls, wet weight of cerebrum, cerebellum and brain stem, and of spinal cord was decreased in the pups exposed to alcohol. DNA and protein contents were also found to be lowered in all the CNS regions of the pups exposed to alcohol. Conversely, maternal alcohol consumption was found to increase the concentration and the content of total ganglioside N-acetyl-neuraminic (NANA) in CNS of the pups. In addition, alcohol treatment was found to induce alterations in the proportions of individual ganglioside fractions. Interestingly, these alterations are somewhat different than those observed in the neonatal brain and spinal cord of the pups subjected to prenatal alcohol exposure. The alterations in the proportions of ganglioside fractions were shown to be region-specific. Maternal alcohol consumption resulted in decreased activities of sialidase, beta-galactosidase, beta-glucosidase and beta-hexosaminidase. The results suggest that the alcohol-associated increases in ganglioside concentration may be at least partly due to the decreased activities of ganglioside catabolizing enzymes.
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PMID:Effect of prenatal and postnatal exposure to ethanol on rat central nervous system gangliosides and glycosidases. 140 63

The enzyme mechanism of sialidase from influenza virus has been investigated by kinetic isotope methods, NMR, and a molecular dynamics simulation of the enzyme-substrate complex. Comparison of the reaction rates obtained with the synthetic substrate 4-methylumbelliferyl-N-acetyl-alpha-D-neuraminic acid and the [3,3-2H]-substituted substrate revealed beta-deuterium isotope effects for V/Km ranging over 1.09-1.15 in the pH range 6.0-9.5, whereas the effects observed for V in this pH range increased from 0.979 to 1.07. In D2O, beta DV/Km was slightly increased by 2% and 5% at pD 6.0 and 9.5 respectively, while beta DV was unchanged. Solvent isotope effects of 1.74 were obtained for both beta DV/Km and beta DV at pD 9.5, with beta DV/Km decreasing and beta DV remaining constant at acidic pD. 1H-NMR experiments confirmed that the initial product of the reaction is the alpha-anomer of N-acetyl-D-neuraminic acid. Molecular dynamics studies identified a water molecule in the crystal structure of the sialidase-N-acetyl-D-neuraminic acid complex which is hydrogen-bonded to Asp151 and is available to act as a proton donor source in the enzyme reaction. The results of this study lead us to propose a mechanism for the solvent-mediated hydrolysis of substrate by sialidase that requires the formation of an endocyclic sialosyl cation transition-state intermediate.
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PMID:Evidence for a sialosyl cation transition-state complex in the reaction of sialidase from influenza virus. 162 57

Cultured human fibroblasts contain two sialidases that degrade gangliosides such as GM3: a lysosomal activity that appears identical with the activity towards water-soluble substrates and that is deficient in the genetic lysosomal disorder sialidosis, and another enzyme that seems localized on the external surface of the plasma membrane. In this report we show that both enzymes can be differentiated in the presence of each other by choice of the detergent used for activation, and also by the inhibitory action of some polyanionic compounds such as sulphated glycosaminoglycans. The lysosomal ganglioside GM3 sialidase is greatly stimulated by sodium glycodeoxycholate and, to lesser degrees, by sodium glycocholate and sodium cholate. The ganglioside GM3 sialidase of the plasma membrane is not measurably active under the conditions of the lysosomal enzyme but is specifically activated by the non-ionic detergent Triton X-100. The glycodeoxycholate-stimulated, but not the Triton-activated, ganglioside GM3 sialidase activity was profoundly diminished in cell lines from patients with the lysosomal disorders sialidosis and galactosialidosis; however, both activities were normal in fibroblasts from patients with mucolipidosis IV, previously thought to be a ganglioside sialidase deficiency disorder. Both the lysosomal and the plasma membrane ganglioside GM3 sialidases were inhibited by sialic acids, suramin, dextran sulphate and sulphated glycosaminoglycans. Among the latter, heparin and heparan sulphate showed a much higher inhibitory potency towards the plasma membrane ganglioside GM3 sialidase than towards the lysosomal onw.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lysosomal and plasma membrane ganglioside GM3 sialidases of cultured human fibroblasts. Differentiation by detergents and inhibitors. 191 May 82

In workers exposed to Cd (8 years on the average), we have found a significant decrease of sialic acid in erythrocyte membranes (22.61 +/- 1.84 vs 25.80 +/- 3.01 micrograms/mg of protein in controls, p less than 0.05) and an increase of sialic acid concentration in both urine (276.7 +/- 132.3 vs 174.5 +/- 70.9 micrograms/g of creatinine, p less than 0.05) and plasma (761.8 +/- 83.5 vs 640.4 +/- 70.7 micrograms/ml, p less than 0.01). In rats exposed to Cd (100 ppm in drinking water for 5.5 months), we have observed a reduction of the sialic acid level in erythrocyte membranes (31.4 +/- 1.2 vs 33.4 +/- 1.1 micrograms/mg of protein, p less than 0.01) and glomeruli (12.5 +/- 1.3 vs 13.9 +/- 1.6 micrograms/mg of protein, p less than 0.05). These effects in Cd treated rats were accompanied by a loss of the glomerular barrier selectively as reflected by an increased urinary output of albumin and transferrin. After 10 months of Cd exposure, the albuminuria and transferrinuria were negatively correlated with the sialic acid content of glomerular membranes (r = -0.47 and -0.51, p less than 0.05), which suggests that the depletion of sialic acid is involved in the loss of glomerular barrier function induced by long term Cd exposure. In Cd-treated rats, sialidase activity was enhanced in kidney cortex and in serum but not in glomeruli.
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PMID:Disturbance of sialic acid metabolism by chronic cadmium exposure and its relation to proteinuria. 202 Sep 76

A central belief about ethanol is that it acts mainly by partitioning into the lipid bilayer of membranes. Newer ideas focus on the neuronal synapse and suggest that ethanol can allosterically change protein conformation, as is suggested by studies on GABA-receptor-mediated chloride uptake and on (Na(+)-K+)-ATPase. Several studies from my laboratory suggest that ethanol enhances enzymatic cleavage of sialic acid (SA) from gangliosides, and perhaps also glycoproteins, but does so without stimulating enzyme activity, suggesting conformational changes that affect accessibility. I propose a new model for the cell membrane in the synaptic region, which features gangliosides surrounding membrane proteins, with an interspersed film of water creating hydrogen bonds that anchor SA moieties to membrane protein. I believe that we should consider the possibility that an important action of ethanol, and polar anesthetics, is due to hydrophilic, not hydrophobic, properties and the ability to dehydrate the cell-surface microdomain. Our laboratory has recently advanced the theory that ethanol dehydrates a "solvent regulatory site" of membrane (Na(+)-K+)-ATPase. This principle might be extended to other enzymes and receptor proteins, as well as to the accessibility of sialoglycoconjugates to sialidase (neuraminidase). Hydrogen bonding between SA and polar regions of receptor protein, and the conformation on both imposed by it, would surely be changed by minor degrees of dehydration and substitution of alcohol molecules for water. Ethanol, unlike water, can only hydrogen bond "at one end." Displacement of water by ethanol would not only "free" the SA groups and make them more vulnerable to enzymatic cleavage but also could simultaneously change the conformation of receptor protein. Similarly, ethanol may displace water that links the polar heads of phospholipids to polar portions of receptors proteins. Ethanol may have an even more important and direct effect of substituting for hydrogen-bonded water within protein itself.
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PMID:Dehydration: a new alcohol theory. 217 30

A hot-water extract from the seed of Plantago asiatica showed a potent inhibitory activity against jack bean alpha-mannosidase, and a flavanone glucoside, plantagoside, was isolated as the inhibitor. Plantagoside was a specific inhibitor for jack bean alpha-mannosidase (IC50 at 5 microM) and appeared to be a non-competitive inhibitor of the enzyme. Whereas, negligible or weak inhibitory activities were observed for beta-mannosidase, beta-glucosidase, and sialidase tested. Plantagoside also inhibited alpha-mannosidase activities in mouse liver lysosomal and microsomal fractions, and the enzyme inhibitory activity in microsomal fraction was enhanced in the presence of glucosidase inhibitor, castanospermine. Plantagoside suppressed antibody response to sheep red blood cells and concanavalin A induced lymphocyte proliferation which was measured by [3H]thymidine incorporation.
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PMID:Plantagoside, a novel alpha-mannosidase inhibitor isolated from the seeds of Plantago asiatica, suppresses immune response. 261 Jun 94

Of 266 Chinese crude drugs, the hot water extract from the root of Scutellaria baicalensis showed potent mouse liver sialidase inhibitory activity; in addition, wogonin, wogonin glucuronide, baicalein, and baicalin were identified as the inhibitors. These flavonoids showed almost the same inhibitory activity when 50-125 micrograms/ml doses of the samples were used for the assay, while wogonin and baicalein showed a more potent activity than wogonin glucuronide and baicalin at the lower concentration (10 micrograms/ml). However, these flavonoids, except wogonin, showed negligible inhibitory activity against Arthrobacter ureafaciens sialidase. These results indicated that S. baicalensis extract contains the sialidase inhibitors which are specific to mouse liver sialidase.
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PMID:Inhibition of mouse liver sialidase by the root of Scutellaria baicalensis. 271 86

Clostridium perfringens sialidase was isolated from a culture medium of bacterial cells by ammonium sulfate precipitation (42-85%), followed by purification through Sephadex G-75 gel chromatography, DEAE A-50 anion exchange chromatography, FPLC medium pressure anion exchange chromatography and finally FPLC medium pressure isochromatofocussing. From 9 l culture medium 1.17 mg sialidase was isolated with a specific activity of 295 U/mg. The enzyme appeared to be homogeneous by analytical polyacrylamide gel electrophoresis. The molecular mass was measured to be 66 kDa. Km values ranging from 0.6 to 1.6mM were determined for several oligosaccharides as substrates. The enzyme catalyzed transglycosylation reactions with methanol as a nucleophilic reagent competitive with water. In the enzymatic hydrolysis of the (3'-methoxyphenyl)glycoside of alpha-N-acetylneuraminic acid, increase of methanol concentration had no effect on the release of 3-methoxyphenol. This finding suggests that the formation of the enzyme-glycon intermediate is the rate-determining step for this substrate.
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PMID:Purification and kinetic properties of sialidase from Clostridium perfringens. 288 13


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