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)

Monoclonal antibody M6704, established against the chick neural tube, was shown to recognize a trisialosyl residue, NeuAc alpha 2-8NeuAc alpha 2-8NeuAc alpha 2-3-R of C-series gangliosides. Using this antibody, the developmental changes of C-series gangliosides in fetal rat cerebral cortex have been examined. Two dimensional thin layer chromatography (TLC) enzyme-immunostaining analysis revealed that alkali treatment resulted in a great increase in GT3 that amounted to more than 85% of the total GT3 detected. The alkalilabile form was easily degraded to form GT3 by the action of the receptor-destroying enzyme of influenza C virus, sialate O-acetylesterase, indicating that the antigen was most probably 9-O-acetyl-NeuAc containing GT3. The ganglioside was highly enriched at the 14th gestation day, gradually decreased, and was not detected in adult rat cerebral cortex.
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PMID:Developmentally expressed O-acetyl ganglioside GT3 in fetal rat cerebral cortex. 258 26

The study of biological properties of influenza virus strains belonging to the same subtype A(H1N1) and closely antigenically related, but isolated from different animal species (man, pig and duck), demonstrated that avian strains were more resistant than those isolated from mammals to high temperature and low pH, as shown by titration of residual infectivity in cell cultures (MDCK) and by sialidase assay. The difference in behaviour could be correlated to biological adaptation of the virus to its host. Avian body temperature is 40 degrees C and influenza virus, in ducks, is enterotropic and therefore capable of passing through the low pH values in the upper digestive tract of the animal. These results do not contradict the hypothesis of a possible filiation between avian and mammalian orthomyxoviruses.
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PMID:Comparison of biological and physical properties of human and animal A(H1N1) influenza viruses. 258 48

Influenza viruses have two surface glycoproteins: haemagglutinin and neuraminidase which are capable of inducing a significant antibody response following vaccination. All neuraminidases from different strains of influenza A and B viruses are able to hydrolyse alpha-ketosidic linkages between N-acetylneuraminic (sialic) acid and other carbohydrates. In this report, the neuraminidase activity was assayed in various influenza vaccines by using a fluorogenic substrate: the sodium salt of 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid. This method was reliable (variation less than 8%) and more sensitive (100 to 1000 times) in less time (incubation time = 15 min) than the Warren assay. Therefore, the method is suitable for the control of the sialidase activity during the processing of influenza vaccines.
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PMID:Fluorometric assay for the measurement of viral neuraminidase in influenza vaccines. 275 Feb 67

Flavonoids (103 species) were tested for inhibitory activity against mouse liver sialidase using sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate (PNP-NeuAc) as substrate. Isoscutellarein-8-O-glucuronide from the leaf of Scutellaria baicalensis showed most potent activity (IC50, 40 microM), and this flavone appeared to be a non-competitive inhibitor of the enzyme. This flavone inhibited the lysosomal solubilized sialidase against PNP-NeuAc and sialyllactose effectively, but not microsomal enzyme against gangliosides and colominic acid, whereas, negligible or weak inhibitory activities were observed for influenza virus sialidase, beta-galactosidase, alpha-mannosidase, and alpha-glucosidase tested. These results indicate that this flavone may be useful to elucidate the function of the lysosomal solubilized sialidase.
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PMID:Inhibition of mouse liver sialidase by plant flavonoids. 277 64

Sialate 9(4)-O-acetylesterases (EC 3.1.1.53) have been isolated from equine liver, bovine brain and influenza C virus. In this latter case, the esterase represents the receptor-destroying enzyme of the virus. The kinetic properties of these enzymes were determined with Neu5,9Ac2 and in part with 4-methylumbelliferyl acetate and Neu5,9Ac2-lactose. The Km values vary between 0.13 and 24 mM and the Vmax values from 0.55 to 11 U/mg of protein. The pH optima are in the range of 7.4-8.5, the molecular masses at 56,500 and 88,000 Da. In addition to a fast hydrolysis found for aromatic acetates, such as 4-methylumbelliferyl acetate or 4-nitrophenyl acetate, N-acetyl-9-O-acetylneuraminic acid is de-O-acetylated at the highest relative rate. Other substituents at the 9-position, such as lactoyl residues, or acetyl groups at other positions within the side chain are not hydrolyzed. Neu4,5Ac2, however, is a substrate for all 3 enzymes. The hydrolysis rates of this ester function, which renders sialic acids resistant to the action of sialidases, vary from 3 to 100% relative to Neu5,9Ac2. Whereas Neu5,9Ac2-lactose is hydrolyzed by the bovine and viral esterases, other O-acetylated sialic acids in glycoconjugates are only attacked by the enzyme from influenza C virus and not by that from bovine brain. The esterase from horse liver also releases 4-O-acetyl groups from equine submandibular gland mucin. By incubation with appropriate substrates and inhibition studies, carboxylesterase, amidase and choline esterase activities were excluded, as well as the cleavage of other acyls, e.g., butyryl groups. Thus, the enzymes investigated belong to the acetylesterases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sialate O-acetylesterases: key enzymes in sialic acid catabolism. 314 20

An esterase was isolated from influenza C virus with a specific activity from 1.7-5 U/mg protein, and its substrate specificity was tested with various naturally occurring O-acylated sialic acids, synthetic carbohydrate acetates, and other esters. The enzyme hydrolyses only acetic acid esters at significant rates. The non-natural substrates 4-methyl-umbelliferyl acetate, 4-nitrophenyl acetate, and alpha-naphthyl acetate are cleaved at highest hydrolysis rates, followed by the natural substrate N-acetyl-9-O-acetylneuraminic acid. The esterase also acts on N-glycoloyl-9-O-acetylneuraminic acid and, much slower, on N-acetyl-4-O-acetylneuraminic acid; N-acetyl-7-O-acetylneuraminic acid is not hydrolysed. 2-Deoxy-2,3-didehydro-N-acetyl-9-O-acetylneuraminic acid is also a substrate for this enzyme, however, 6-O-acetylated N-acetylmannosamine and glucose are not. Esterification of the carboxyl function of sialic acids strongly reduces or prevents esterase action on O-acetyl groups. The carboxyl ester is not hydrolysed. The relative cleavage rates also depend on the type of the non-sialic acid part of the molecule. N-Acetyl-9-O-acetylneuraminic acid as component of sialyllactose and rat serum glycoprotein shows hydrolysis rates close to the free form of this sugar, while acetyl ester groups of bovine submandibular gland mucin and rat erythrocytes are hydrolysed at slower rates. Gangliosides and 4-O-acetylated glycoproteins are no substrates for the purified enzyme. A slow hydrolysis is observed by incubation of 9-O-acetylated GD1a with intact influenza C viruses. As other natural acetyl esters (acetyl-CoA and acetylthiocholine iodide) are not hydrolysed, the enzyme can be classified as sialate 9(4)-O-acetylesterase (EC 3.1.1.53).
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PMID:Isolation and characterization of sialate 9(4)-O-acetylesterase from influenza C virus. 324 42

The relationship between the mitogenic activity of influenza type A viruses for murine B lymphocytes and the receptor-binding specificity of their hemagglutinin was examined. Receptor-binding specificity was determined by the ability of the virus to agglutinate erythrocytes that had been sialidase treated and then enzymatically resialylated to contain sialyloligosaccharides with defined sequences. Distinct differences in receptor-binding specificity were observed between strongly and weakly mitogenic viruses of the H3 subtype, with strong mitogenic activity correlating with the ability of the virus to recognize the sequence N-glycolylneuraminic acid alpha 2,6 galactose (NeuGc alpha 2,6Gal). Viruses isolated early in the evolution of the H3 subtype (from 1968 to 1971) are relatively weak mitogens and recognize the sequence N-acetylneuraminic acid alpha 2,6 galactose (NeuAc alpha 2,6Gal) but not NeuGc alpha 2,6Gal. H3 viruses isolated since 1972 are strongly mitogenic, and these viruses recognize both NeuGc alpha 2,6Gal and NeuAc alpha 2,6Gal. The amino acid substitution of Tyr for Thr at residue 155 of HA1 may be critical to this change in receptor-binding specificity and mitogenic activity of the later H3 viruses. Horse serum-resistant variants of H3 viruses, which bind preferentially to the sequence NeuAc alpha 2,3Gal, are poorly mitogenic. Differences were also observed between the receptor-binding specificity of the strongly mitogenic H3 viruses and viruses of the H2 and H6 subtypes, the mitogenic activity of which is limited to strains of mice that express the class II major histocompatibility complex glycoprotein I-E. The results indicate that the receptor-binding specificity of the hemagglutinin plays a critical role in determining the mitogenic activity of influenza viruses.
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PMID:Relationship between mitogenic activity of influenza viruses and the receptor-binding specificity of their hemagglutinin molecules. 349 May 81

The neuraminidase associated with the bifunctional protein, hemagglutinin-neuraminidase, of influenza virus has been characterized. The enzyme has a pH optimum of 4.5, does not require Ca2+ and is inactivated (98%) by incubation at 50 degrees C. The enzyme has a Km of 2.00 X 10(-3) M and 0.06 X 10(-3) M with the substrates 2-(3-methoxyphenyl)-N-acetylneuraminic acid and fetuin, respectively. The Ki is 400 X 10(-6) with the inhibitor 2-deoxy-2,3-dehydro-N-acetylneuraminic acid. The incorporation of labeled cysteine, valine and leucine in the hemagglutinin-neuraminidase protein is different from that of viral neuraminidase. A comparison of the properties of the neuraminidase associated with protein hemagglutinin-neuraminidase with that of viral neuraminidase or sialidase showed that the former is biochemically different and an antigenically distinct enzyme. The unique feature of the new enzyme is that it has the hemagglutinin activity as well. The two biological activities could not be separated from each other in all systems used. Apparently, protein hemagglutinin-neuraminidase is genetically transferable and it is detectable in a laboratory recombinant virus E-2971 (H3 Aichi X N7). These results suggest that protein hemagglutinin-neuraminidase is a unique surface protein of the influenza virus A/Aichi/2/68 (H3N2).
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PMID:Characterization of influenza virus neuraminidase with hemagglutinin activity and its comparison with that of viral neuraminidase. 353 57

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

A cryptically I-active sialylglycoprotein (glycoprotein 2) isolated from bovine erythrocyte membranes as Sendai virus receptor (Suzuki, Y., Suzuki, T. and Matsumoto, M. (1983) J. Biochem. 93, 1621-1633) contains N-glycolylneuraminic acid (NeuGc) as its predominate sialic acid and exhibits poor receptor activity for a variety of influenza viruses. Enzymatic modification of asialoglycoprotein-2 to contain N-acetylneuraminic acid (NeuAc) in the NeuAc alpha 2-3Gal and NeuAc alpha 2-6Gal sequences using specific sialyltransferase resulted in the appearance of receptor activity toward human influenza viruses A and B. The biological responsiveness chicken erythrocytes treated with sialidase and then reconstituted with derivatized glycoprotein 2 showed considerable recovery to influenza virus hemagglutinin-mediated agglutination, low-pH fusion and hemolysis. Specific hemagglutination inhibition activity of derivatized glycoprotein 2 was 5-16-times higher than that of human glycophorin. A/PR/8/34 (H1N1) virus preferentially recognized derivatized glycoprotein 2 containing NeuAc alpha 2-3Gal sequence over that containing NeuAc alpha 2-6Gal while the specificity of A/Aichi/2/68 (H3N2) for the sialyl linkages was reversed. B/Lee virus recognized both sequences almost equally. The biological responsiveness to the viruses of the erythrocytes labeled with the derivatized glycoprotein 2 containing NeuGc was considerably lower than that of derivatized glycoprotein 2 containing NeuAc. The results demonstrate that the hemagglutinins of human isolates of influenza viruses A and B differ in the recognition of microdomains (NeuAc, NeuGc) of the receptors for binding and fusion activities in viral penetration and the sequence to which sialic acid (SA) is attached (SA alpha 2-3Gal, SA alpha 2-6Gal). Inner I-active neolacto-series type II sugar chains may be important in revealing the receptor activity toward the hemagglutinin of both human influenza viruses A and B.
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PMID:The hemagglutinins of the human influenza viruses A and B recognize different receptor microdomains. 366 54


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