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)

Plasma of normal human individuals was shown to contain an inhibitor of Trypanosoma cruzi neuraminidase (NAase; acylneuraminyl hydrolase, sialidase, EC 3.2.1.18). The inhibitor has been purified to homogeneity by PEG precipitation, CM Affi-Gel Blue Sepharose chromatography, and gel filtration. The purified preparation inhibits T. cruzi NAase at a concentration as low as 10(-9) M and has no effect at concentrations at least 100 times higher on any of the other NAases tested, including those from influenza virus, the closely related trypanosome Trypanosoma rangeli, and mammalian NAases. The inhibitor is unique in that it prevents T. cruzi desialylation of intact mammalian cells but does not prevent desialylation of soluble glycoconjugates. In addition, the isolated material is effective in inhibiting the T. cruzi NAase whether the enzyme is on the parasite outer membrane or in solution. Molecular characterization indicates that the inhibitor is a glycoprotein with a Mr of 246,000 +/- 20,000 composed of subunits of Mr 28,000 +/- 2000. Its plasma concentration is at least 60 micrograms/ml. The mechanism of action has not been fully elucidated, but it appears to be noncompetitive. Attempts to match the isolated NAase inhibitor with known plasma glycoproteins have not been successful. In view of this and of the specificity of the inhibitor for T. cruzi, we have named the inhibitor "cruzin." This finding suggests a different approach in investigating the role that NAase plays in host-parasite interaction.
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PMID:Specific inhibition of Trypanosoma cruzi neuraminidase by the human plasma glycoprotein "cruzin". 355 30

In this report we study the interaction of reovirus type 3 Dearing (RV3) with vertebrate erythrocytes whose membrane glycoconjugates differ in the degree and position of O-acetylation of their sialic acid (NeuAc) residues. Binding to erythrocytes required the presence of NeuAc on cellular glycoconjugates, since pretreatment with sialidase (neuraminidase) abolished hemagglutination by RV3. Furthermore, we found that RV3 binds efficiently to and hemagglutinates all erythrocyte preparations possessing exclusively NeuAc, or a mixture of NeuAc and 4-O-acetyl-NeuAc (4-O-Ac-NeuAc), but poorly to erythrocytes bearing a mixture of 9-O-Ac-NeuAc and NeuAc, suggesting that RV3 binds preferentially to NeuAc-containing glycoconjugates. To gain further evidence for this hypothesis we treated chicken erythrocytes with influenza C virus neuraminate, 9-O-acetylesterase, to convert their 9-O-Ac-NeuAc residues to NeuAc. When hemagglutination assays were carried out on these cells, we observed a 16-fold increase in the hemagglutination titer for RV3 compared to untreated cells. When we treated bovine submaxillary mucin (BSM) with influenza C virus, we observed a dramatic increase in its potency as an inhibitor of RV3 hemagglutination. Concomitant with this, the 9-O-Ac-NeuAc residues on BSM were converted to NeuAc. Taken together and in conjunction with a previous report (A. F. Pacitti and J. R. Gentsch, 1987, J. Virol. 61 1407-1415), these results suggest that the virion attachment protein exhibits a strong preference for NeuAc over 9-O-Ac-NeuAc as a receptor component on erythrocytes.
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PMID:Differential interaction of reovirus type 3 with sialylated receptor components on animal cells. 367 31

The influence of neuraminidase on the immunogenicity of heterologous erythrocytes as determined by serum haemagglutination titres was investigated in mice. For this study sheep and rabbit erythrocytes were selected because of their high and low N-acetylneuraminic (sialic) acid content, respectively. Preincubation with neuraminidase resulted in a ten-fold reduction of the immunogenicity of sheep erythrocytes (ShE). By contrast, the immune response to rabbit erythrocytes appeared to be resistant to sialidase treatment. Addition of the extrinsic adjuvant dimethyldioctadecylammonium bromide largely restored the immunogenicity of neuraminidase-treated ShE, but did not change the response to control-treated ShE. The maximal antibody level induced by neuraminidase-treated ShE was lower than that provoked by control ShE. These results suggest that sialic acid is both an intrinsic immunological adjuvant and an antigenic determinant of ShE. The adjuvant effect of sialic acid does not depend on complement component C3 as judged by the response of cobra venom factor-pretreated animals. In genetically C5-deficient and in nude mice, however, sialic acid showed diminished and absent adjuvant activity, respectively.
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PMID:Surface-associated sialic acid is an immunological adjuvant. 409 53

A test was developed to screen drugs for antineuraminidase (influenza sialidase) activity in vitro. Neuraminidase prepared from Vibrio cholerae was added to a substrate containing ganglioside, prepared from calf brain. Sialic acid is a split product in the reaction. The presence of sialic acid was detected colorimetrically by use of Warren's Thiobarbituric Acid Assay after drugs had been added to inhibit the action of neuraminidase on the calf brain substrate.
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PMID:Method for determining antineuraminidase activity. 602 25

Sulfated acidic mucopolysaccharides have been found to be significant components of "protein plugs" in patients with chronic pancreatitis. The precise identification of the mucopolysaccharides and their distribution within the protein plugs may clarify the pathogenesis of the plugs. Pure pancreatic juice from five patients with chronic pancreatitis was obtained by endoscopic retrograde catheterization of the papilla of Vater. Enzymes for digestion of the plugs included hyaluronidase of the bovine testes and streptomyces hyalurolyticus, chondroitinase ABC and AC, and sialidase (neuraminidase). Our study indicated that: I) Sialic acid is distributed throughout the plugs and may be a major component, followed by a lesser amount of chondroitin sulfate B. 2) Chondroitin sulfate A, C, D and E and chondroitin may be minor components. 3) Hyaluronic acid is negligible in the plugs.
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PMID:Histochemical studies on enzyme-digested protein plugs of patients with chronic pancreatitis: a preliminary report. 622 98

A family is described in which three members had an elevated total serum thyroxine level and free thyroxine index. Each affected subject was clinically euthyroid and had a normal pulse wave arrival time (QKd), serum triiodothyronine and free thyroxine levels, and a normal serum thyroxine-binding globulin (TBG) concentration. Electrophoresis of their serum with 125I-labeled thyroxine revealed increased thyroxine binding in the albumin region. In addition, this abnormal protein, like thyroxine-binding globulin, bound 125I-labeled triiodothyronine and 125I-labeled reverse triiodothyronine. However, electrophoresis of serum treated by sialidase (neuraminidase) digestion suggested that this abnormal protein is not an anomalous form of thyroxine-binding globulin "buried" in the albumin area. These cases of euthyroid familial hyperthyroxinemia due to an abnormal thyroid hormone-binding protein show that an elevated serum thyroxine level or free thyroxine index is not always sufficient to confirm the presence of thyrotoxicosis.
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PMID:Euthyroid familial hyperthyroxinemia due to abnormal thyroid hormone-binding protein. 628 40

A sialidase (neuraminidase, acylneuraminosyl hydrolase, EC 3.2.1.18) has been discovered and isolated from Gardnerella vaginalis (ex. Haemophilus vaginalis), a possibly pathogenic inhabitant of the female genital tract. Bacteria were grown in peptone-yeast-extract medium with 2.0 mM N-acetylmannosamine as enzyme inductor under CO2 atmosphere. Sialidase activity was found in the bacterial sediment and in the culture medium. The enzyme was liberated from the cells by ultrasonic treatment. Purification was performed by 60-80% ammonium sulfate precipitation and by column chromatography on Sepharose CL-6B and Sephadex G 200. The enzyme revealed a molecular weight in the range of Mr 75 000 and a pH optimum at 5.5. Among the different types of NeuAc-containing glycoconjugates, the enzyme exhibits its highest activities towards the globular glycoproteins alpha 1-acid glycoprotein and fetuin. Taking their cleavage rate as 100, it is around 55 for II3NeuAc-Lac, 45 for bovine submaxillary mucin, 35 for II6NeuAc-Lac and IV3, III6NeuAc2-LcOse4. The rates for III8,II3NeuAc2-Lac, gangliosides and colominic acid are below 20. Due to its specificity pattern, the enzyme may play a role in the pathogenic process of G. vaginalis infections.
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PMID:A newly discovered sialidase from Gardnerella vaginalis. 633 32

The sialic-rich carbohydrate moiety of the neural cell adhesion molecule (N-CAM) undergoes major structural changes during development and plays a significant role in altering the homophilic binding of the molecule. In order to understand the mechanism of these changes, a cyanogen bromide (CNBr) fragment that contained 90% of the sialic acid of N-CAM was isolated and characterized according to the number of carbohydrate attachment sites and reactivity with specific monoclonal antibodies. The CNBr sialopeptide migrated on SDS PAGE as a broad zone of Mr 42,000-60,000. Upon treatment with neuraminidase, it was converted to a single component of Mr 42,000, and subsequent, limited treatment with endoglycosidase F gave four evenly spaced components of Mr 35,000-42,000, suggesting that it contained three attachment sites for N-linked oligosaccharides. The fragment reacted with monoclonal antibody 15G8, which detects the sialic acid in embryonic N-CAM, and with a monoclonal antibody, anti-(N-CAM) No. 2. Treatment with neuraminidase or with endoglycosidase F destroyed reactivity with 15G8 but not with anti-(N-CAM) No. 2. A similar CNBr sialopeptide was obtained from adult N-CAM; it contained sialic acid, had three N-linked oligosaccharides and reacted with anti-(N-CAM) No. 2 but not with 15G8 monoclonal antibodies. A peptide fragment, Fr2, comprising the NH2 terminal and middle regions of the molecule yielded a CNBr fragment closely similar to the fragment obtained from the whole molecule. The CNBr fragment from Fr2 reacted with monoclonal antibody anti-(N-CAM) No. 2. Fr1, comprising the NH2 terminal region alone, failed to react. These data confirm that the majority of the sialic acid is localized in the middle region of the N-CAM molecule and support the hypothesis that embryonic to adult conversion of N-CAM is the result of differences in sialidase or sialytransferase activity.
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PMID:Mapping of three carbohydrate attachment sites in embryonic and adult forms of the neural cell adhesion molecule. 638 28

A deficiency of glycoprotein neuraminidase (sialidase, acylneuraminyl hydrolase, EC 3.2.1.18) activity was found in fibroblasts from a patient with the clinical symptoms of Morquio disease type A (mucopolysaccharidosis IV A). Residual neuraminidase activity was about 5% of the mean normal activity. N-Acetylgalactosamine-6-sulfate (GalNAc-6-S) sulfatase activity was reduced to less than 1% of normal with a pH-optimum of 3.0 as expected for the severe form of Morquio disease. In peripheral leucocytes of the patient, however, neuraminidase activity but not Ga1NAc-6-S sulfatase activity was in the normal range. Mixing experiments excluded the presence of excessive amounts of inhibitors of neuraminidase activity.
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PMID:Partial deficiency of glycoprotein neuraminidase in some patients with Morquio disease type A. 642 47

The attachment of Actinomyces naeslundii ATCC 12104 to human buccal epithelial cells pre-treated with neuraminidase (sialidase) was evaluated. Both commercial clostridial neuraminidase and neuraminidase preparations from the test strain of A. naeslundii enhanced attachment. The results suggest that the A. naeslundii beta-galactoside-seeking ligand involved in hemagglutination and interbacterial coaggregation also mediates one type of binding to human buccal epithelial cells.
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PMID:Neuraminidase-activated attachment of Actinomyces naeslundii ATCC 12104 to human buccal epithelial cells. 657 31


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