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)

Lysosomal neuraminidase (sialidase; EC 3.2.1.18) and beta-galactosidase (EC 3.2.1.23), together with a carboxypeptidase, the so-called 'protective protein', were co-purified from the human placenta by affinity chromatography on a concanavalin A-Sepharose column followed by a thiogalactoside-agarose affinity column for beta-galactosidase. Analysis of the purified material by gel-filtration h.p.l.c. revealed three distinct molecular forms, all with high beta-galactosidase specific activity, but only the largest one expressed neuraminidase activity. Rechromatography of each individual species separately indicated that all three are in fact part of an equilibrium system (the neuraminidase-beta-galactosidase-carboxypeptidase complex or NGC-complex) and that these species undergo slow conversion into one another through dissociation and association of protomeric components. Each species was sufficiently stable for the determination of their hydrodynamic properties by gel-filtration h.p.l.c. and sedimentation velocity. The largest species had an apparent sedimentation coefficient S20.w, of 18.8 S and a Stokes' radius of 8.5 nm, giving a molecular mass of 679 kDa and a fractional ratio, f/f min, of 1.47. The latter value indicates that the macromolecule is asymmetric or highly hydrated. This large species is composed of four types of polypeptide chains of molecular mass 66 kDa (neuraminidase), 63 kDa (beta-galactosidase), 32 kDa and 20 kDa (carboxypeptidase heterodimer). The 32 kDa and 20 kDa protomers are linked together by a disulphide bridge. Glycopeptidase F digestion of the NGC-complex transformed the diffuse 66-63 kDa band on the SDS gel into two close but sharp bands at 58 and 56 kDa. The two smaller species which were separated on the h.p.l.c. column correspond to tetrameric and dimeric forms of the 66-63 kDa protomers and express exclusively beta-galactosidase activity. Treatment of the NGC-complex with increasing concentrations of guanidinium hydrochloride up to 1.5 M also resulted in dissociation of the complex into the same smaller species mentioned above plus two protomers of molecular mass around 60 and 50 kDa. A model of the largest molecular species as a hexamer of the 66-63 kDa protomers associated to five carboxypeptidase heterodimers (32 kDa and 20 kDa) is proposed
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PMID:Structure of the lysosomal neuraminidase-beta-galactosidase-carboxypeptidase multienzymic complex. 210 3

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

Viridans group streptococci were examined for the production of sialidase (neuraminidase) activity, using the fluorescent substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid in a simple and rapid (15-min) assay. Sialidase was produced by all strains of Streptococcus oralis and S. intermedius and by a majority of S. mitis strains. S. mutans, S. sobrinus, S. gordonii, S. sanguis, S. vestibularis, S. salivarius, S. anginosus, S. constellatus, "S. parasanguis," and the "tufted fibril group" were uniformly negative. Sialidase production may be a useful characteristic to assist in the identification of viridans group streptococci.
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PMID:Sialidase activity of the "Streptococcus milleri group" and other viridans group streptococci. 219 5

This report deals with the development of human conjunctival goblet cells. Fifty-six eyes of human embryos and fetus ranging from 5 to 41 weeks of gestational age were used in this study. Glycosaminoglycans in the goblet cells were investigated histochemically using 1% alcian blue staining (pH = 2.5) and PAS reagent staining and sialidase (neuraminidase) digestion. At 8 weeks, goblet cells appeared in the forniceal area, and they extended to the palpebral and bulbar conjunctiva. These cells were already similar to adult goblet cells. Alcian blue staining and the enzyme digestion method revealed the existence of sialic acid in the goblet cells from 9 weeks. These results suggest that at the early developmental stage the goblet cells develop from the forniceal area. It is also indicated that the goblet cells in the early developmental stage are already similar to cells in the adult stage because they contain mainly sialic acid as glycosaminoglycans.
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PMID:[Morphological and histochemical studies on the development of human conjunctival goblet cells]. 236 Apr 86

Carbohydrate substituents on the large peptide of the voltage-sensitive Na channel from Electrophorus electricus electroplax have been partially characterized by their sensitivity to endoglycosidases H and F, peptide:N-glycosidase F, Endo-N-acetylneuraminidase, and to neuraminidase. The results suggest the presence of at least two classes of oligosaccharides: neutral, high mannose or hybrid oligosaccharides, and acidic, complex oligosaccharides with a core-structure terminating in an unbranched homopolymer of sialosyl units in alpha-2,8 linkages (much greater than 5 tandem sialic acids). Large decreases in apparent Mr produced by sialidase treatments suggest an extended carbohydrate structure that could inhibit protein-protein interaction. Polysialic acid was formerly proposed to be a unique constituent of neural cell adhesion molecules (N-CAMs) in vertebrates. However, ratios of sialic acid to galactose reported for mammalian brain and muscle Na channels suggest they may also carry this oligosaccharide.
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PMID:Multiple oligosaccharide chains in the voltage-sensitive Na channel from electrophorus electricus: evidence for alpha-2,8-linked polysialic acid. 244 1

A partially-purified neuraminidase from the mucinase complex of Vibrio cholerae was used to prepare a specific anti-neuraminidase antiserum in rabbits. When the neutralising potency of this serum against V. cholerae neuraminidase was assessed in conventional tests, the enzymic activity, as measured by thiobarbituric acid, methoxyphenol-neuraminate and goblet-cell assays, apparently increased. These results are attributable to the presence of a sialylated glycoprotein substrate and small amounts of sialidase in the crude antiserum. However, a twice-purified DEAE-IgG fraction of the antiserum neutralised the enzymic activity of the V. cholerae neuraminidase.
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PMID:Studies on the Vibrio cholerae mucinase complex. III. Neutralisation of the neuraminidase activity by specific anti-neuraminidase IgG. 244 60

We had previously shown that the human colon produces at least two immunochemically distinct mucins, one neutral and the other a sialomucin [Gold et al. J. biol. Chem. 256, 6354-6358 (1981)]. In addition, the sialomucin was shown to contain an immunodeterminant restricted to colonic epithelium and may thus prove useful as a tissue-specific marker. In the current study we have shown that a specific linkage of sialic acid to the oligosaccharide backbone has a major role in the organ-specific immunodeterminant structure. Treatment of intact colonic mucin with sialidase (Cl. perfringens) cleaved 20-80% of the sialic acid as measured colorimetrically. Immunoreactivity was decreased by 0-42% with respect to the untreated material. Saponification (0.1 N KOH, 20 min at room temp) caused an approximate 90% decrease in immunoreactivity for each mucin. Subsequent to saponification, neuraminidase cleaved most of the sialic acid from the mucins. The majority of sialic acid was observed to be O-acetylated, thus making it sialidase-insensitive. Gas chromatography-mass spectrometric analyses of the trimethylsilyl sialic acid derivatives indicated the presence of NeuNAc; NeuNAc, 9-OAc; and NeuNAc, 7,9 diOAc as the major sialyl derivatives. The radioimmunoassay data appeared to indicate that O-acetylated sialic acid was necessary for immunoreactivity. It should be noted that jejunal mucin and bovine submaxillary mucin also contain O-acetylated sialic acid, but did not inhibit in our radioimmunoassay. This may have been due to differences in the O-acetylation pattern or the linkage of sialic acid to the core carbohydrate. Analyses of the partially methylated alditol acetate derivatives by gas chromatography-mass spectrometry of the untreated, as well as the saponified and neuraminidase treated, mucins revealed that sialic acid was attached to the carbohydrate core either to galactose, N-acetylglucosamine, and/or N-acetylgalactosamine. Linear regression analyses comparing immunoreactivity with specific epitope concns, in conjunction with RIA analyses of known structures, suggested that the organ-specific immunodeterminant was (or was dependent upon the presence of) the structure GlcNAc (1,3)[O-acetylated Neu5Ac(2,6)] GalNAc.
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PMID:Studies on the structure of the organ-specific determinant of human colonic mucin. 247 76

A rapid method for the detection of acetylneuraminyl hydrolase, EC 3.2.1.18 (sialidase or neuraminidase), was developed by using 2'-(4-methylumbelliferyl)alpha-D-N-acetylneuraminic acid as substrate in a filter paper spot test. The method was compared to conventional assays that use 2'-(4-methylumbelliferyl)alpha-D-N-acetylneuraminic acid and bovine submaxillary mucin and was found to be in excellent agreement. Organisms with greater than 10 U of enzyme activity (in nanomoles per minute per milligram of cell protein) gave positive reactions, while those with 2.7 to 9.0 U gave only weak reactions. Isolates with less than 2.7 U of activity were detected upon prolonged incubation. Sialidase activity was detected in 79% of 71 clinical isolates representing five species of Actinomyces. The percentage of sialidase-producing isolates of each species varied considerably: Actinomyces israelii, 63%; A. meyeri, 73%; A. naeslundii, 85%; A. odontolyticus, 73%; and A. viscosus, 100%.
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PMID:Detection of sialidase (neuraminidase) activity in Actinomyces species by using 2'-(4-methylumbelliferyl)alpha-D-N-acetylneuraminic acid in a filter paper spot test. 264 20

A human monoclonal antibody termed HMST-1 was produced by fusing lymphocytes from segments of human pelvic lymph nodes from an endometrial cancer patient with murine myeloma cells. The epitope recognized by HMST-1 was determined to be lacto-series type 1 chain-containing glycosphingolipid (Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer) by isolating the antigen from endometrial cancer cell line SNG-II and analyzing with fast atom bombardment mass spectrometry, permethylation analysis, and exoglycosidase treatment. By the immunohistochemical avidin-biotin-peroxidase complex method, no normal endometrium and benign endometrial hyperplasia were stained with HMST-1, but HMST-1 reacted with about 35% of endometrial cancer cases. These facts indicate that the rate of expression of the antigen increases along with the course of malignancy in the endometrium. By sialidase treatment of the section, the positive rate increased to 57% in endometrial cancers and to 13% in normal endometrium, indicating that the antigen was masked with sialic acid and exposed by neuraminidase treatment. Immunohistochemistry also revealed that the antibody reacted with human fetal alimentary tract epithelium and mesothelium, indicating the oncodevelopmental nature of Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer.
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PMID:Human monoclonal antibody (HMST-1) against lacto-series type 1 chain and expression of the chain in uterine endometrial cancers. 268 63

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


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