Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NEURAMINIDASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1994

An immobilized-enzyme system for the determination of sialic acid using cloned neuraminidase from Clostridium perfringens A.T.C.C. 10543.

Neuraminidase expressed by cloned nanH of Clostridium perfringens has been immobilized and employed to determine the concentration of sialic acid in human serum. Two enzyme pairs, cloned neuraminidase-N-acetylneuraminate (NANA) lyase and pyruvate oxidase-peroxidase, have been respectively co-immobilized on to 1,12-aminododecane-agarose with glutaraldehyde. The relative specific activities of the co-immobilized neuraminidase and NANA lyase were 61 and 77%, and those of pyruvate oxidase and peroxidase were 51 and 96% of the corresponding soluble enzymes respectively. The optimal reaction pH at 37% C for each of the co-immobilized enzymes was about 1 pH unit higher than that of the corresponding soluble enzyme. The optimal reaction temperature of peroxidase was increased as a result of immobilization. The thermostability of the immobilized cloned neuraminidase, NANA lyase, pyruvate oxidase and peroxidase were increased 80-, 83-, 115- and 147-fold at 45 degrees C over the soluble forms respectively. The results correlated satisfactorily with those obtained by using a soluble enzyme system. The system is thus a reliable assay method for sialic acid in serum.

Cloning, Molecular↗
PubMed1990

The hemagglutinin-neuraminidase glycoproteins of human parainfluenza virus type 1 and Sendai virus have high structure-function similarity with limited antigenic cross-reactivity.

Human parainfluenza virus type 1 (hPIV-1) is closely related to Sendai virus on the basis of cross-reactivity of antisera. We examined this association further by using monoclonal antibodies to the Sendai virus hemagglutinin-neuraminidase (HN) glycoprotein to determine the relationship between overall protein structure and the hemagglutination and neuraminidase functions. Of 10 monoclonal antibodies representing four nonoverlapping antigenic sites on the HN of Sendai virus, only 4 from two sites cross-reacted with hPIV-1, indicating a limited conservation of epitopes. One of these four inhibited the hemagglutinating activity of hPIV-1 comparably to Sendai virus, but none appreciably inhibited the neuraminidase activity of hPIV-1. The ability of some of these monoclonal antibodies to inhibit only hemagglutinating or neuraminidase activity of either virus provided evidence for two separate active sites on the HN molecule. To determine the overall structural relationship of the HNs of hPIV-1 and Sendai virus, we cloned and sequenced the HN gene of hPIV-1. The HN clone was made from genomic RNA and was identified by hybrid-arrested in vitro translation of mRNA. The predicted HN protein sequence of hPIV-1 was identical in length to that of Sendai virus and had a shared identity of 72%. There was a marked conservation of structural elements (cysteines, prolines, and glycines), which would predict a similar molecular conformation. However, there were 10 potential glycosylation sites on the HN of hPIV-1, compared with 5 on Sendai virus. Some of these sites may be responsible for the inability of the Sendai virus monoclonal antibodies to cross-react. The results of our study support a close structure-function relationship between hPIV-1 and Sendai virus but suggest limited antigenic cross-reactivity.

Amino Acid Sequence↗
PubMed1991

Fusion properties of cells persistently infected with human parainfluenza virus type 3: participation of hemagglutinin-neuraminidase in membrane fusion.

Cells persistently infected with human parainfluenza virus type 3 (HPF3) exhibit a novel phenotype. They are completely resistant to fusion with each other but readily fuse with uninfected cells. We demonstrate that the inability of these cells to fuse with each other is due to a lack of cell surface neuraminic acid. Neuraminic acid is the receptor for the HPF3 hemagglutinin-neuraminidase (HN) glycoprotein, the molecule responsible for binding of the virus to cell surfaces. Uninfected CV-1 cells were treated with neuraminidase and then tested for their ability to fuse with the persistently infected (pi) cells. Neuraminidase treatment totally abolished cell fusion. To extend this result, we used a cell line deficient in sialic acid and demonstrated that these cells, like the neuraminidase-treated CV-1 cells, were unable to fuse with pi cells. We then tested whether mimicking the agglutinating function of the HN molecule with lectins would result in cell fusion. We added a panel of five lectins to the neuraminic acid-deficient cells and showed that binding of these cells to the pi cells did not result in fusion; the lectins could not substitute for interaction of neuraminic acid with the HN molecule in promoting membrane fusion. These results provide compelling evidence that the HN molecule of HPF3 and its interaction with neuraminic acid participate in membrane fusion and that cell fusion is mediated by an interaction more complex than mere juxtaposition of the cell membranes.

Animals↗
PubMed1994

Site-directed mutagenesis of a conserved hexapeptide in the paramyxovirus hemagglutinin-neuraminidase glycoprotein: effects on antigenic structure and function.

The sequence NRKSCS constitutes the longest linear stretch in the amino acid sequence of the hemagglutinin-neuraminidase (HN) glycoprotein of the paramyxoviruses that is completely conserved among all viruses in the group. We have used site-directed mutagenesis and expression of the mutated HN protein of one member of the group, Newcastle disease virus, to explore the role of this highly conserved sequence in the structure and function of the protein. Any substitution introduced for each of four residues in the sequence, N-234, R-235, K-236, or S-237, results in a drastic decrease in neuraminidase activity relative to that of the wild-type protein. Only substitutions for the terminal serine residue in the sequence had comparatively little effect on this activity. These findings are consistent with prior computer-based predictions of protein secondary structure which had suggested that this domain corresponds to one in the beta-sheet propeller structure of the neuraminidase protein of influenza virus closest to the center of the sialic acid binding site and forms part of the enzyme active site. Four of the substitutions, N-234-->Y and K-236-->E, -->Q, and -->S, apparently cause a local alteration in the antigenic structure of the protein. This is evidenced by (i) the diminished recognition of the protein only by monoclonal antibodies thought to bind at the neuraminidase active site, among an extensive panel of conformation-specific antibodies, and (ii) the slower rate of migration in sodium dodecyl sulfate-polyacrylamide gel electrophoresis for all except the K-236-->Q mutation. One of the mutations, K-236-->S, completely abolishes the ability of the protein to promote cellular fusion when coexpressed with the fusion protein. The latter cannot be explained by a decrease in the relative hemadsorption activity of the protein and suggests that the globular head of the protein may contribute to this process beyond providing receptor recognition.

Amino Acid Sequence↗
PubMed1971

Cells persistently infected with Newcastle disease virus. 3. Thermal stability of hemagglutinin and neuraminidase of a mutant isolated from persistently infected L cells.

Data were obtained which indicated the possible cause of the defective elution from erythrocytes of the mutant virus (NDV(pi)) isolated from L cells persistently infected with the Herts strain of Newcastle disease virus (NDV(o)). The chicken erythrocyte receptors for the mutant and wild-type viruses were equally sensitive to the action of Vibrio cholera filtrate neuraminidase; this suggests that the failure of NDV(pi) to elute from chicken erythrocytes is not due to a specific neuraminidase-resistant receptor for this virus on the erythrocyte membrane. There was no difference in the enzyme content of the intact virions of NDV(o) and NDV(pi) when tested with a soluble substrate, indicating that the inefficient elution of NDV(pi) was not due to a reduced enzyme content. The neuraminidase activity of intact NDV(pi) virions was significantly more stable at 55 C than the enzyme of NDV(o) virions, whereas the dissociated enzymes of the two viruses were inactivated at the same rate. On the basis of these findings, it seems likely there is a structural difference between the two viruses. The neuraminidase protein of the mutant NDV(pi) may be incorporated into the viral envelope in such a manner that it is prevented from reacting with the substrate in the erythrocyte membrane, although it can react with a soluble substrate. The hemagglutinin activity of both intact and disrupted NDV(pi) was significantly more resistant to thermal inactivation than that of the wild-type NDV(o). This finding suggests a genetic difference in the hemagglutinin protein of the two viruses.

Animals↗
PubMed2004

Importance of serine 200 for functional activities of the hemagglutinin-neuraminidase protein of Newcastle Disease Virus.

Newcastle disease virus (NDV) is an avian paramyxovirus with replication competence in human tumor cells and interesting anti-neoplastic and immune stimulatory properties. In order to increase tumor selectivity of replication, we prepared mutants from the avirulent strain Ulster with monocyclic replication cycle and adapted them for multicyclic replication in human melanoma cells. Two mutants (M1 and M2) showed interesting functional differences: while M2 showed T cell co-stimulatory effects in a tumor-specific cytotoxic T lymphocyte (CTL) assay, M1 did not. A distinct difference of these 2 virus mutants appeared also when testing their capacity to induce interferon-alpha and -beta as well as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) molecules in human monocytes. Sequence analysis of the hemagglutinin-neuraminidase (HN) molecules of the 2 virus mutants showed 7 non-silent mutational differences. Upon cloning of the HN mutant genes into an expression vector and transfection of cells, only HN derived from M2 (HN-M2) was detected at the cell surface by immunostaining with specific antibodies and showed hemadsorption and neuraminidase activity. In order to define which amino acid was responsible for the loss of functional activity of HN derived from M1 (HN-M1), distinct HN mutants were generated via site-directed mutagenesis and tested. Substitution of serine 200 by a proline abrogated HN expression and its hemadsorption and neuraminidase activities. Molecular modeling revealed that proline 200 in HN influences flexibility of a loop near the entrance to the neuraminidase active site, a function that may be crucial for the functions of this viral protein.

Animals↗
PubMed1999

Use of the oral neuraminidase inhibitor oseltamivir in experimental human influenza: randomized controlled trials for prevention and treatment.

CONTEXT: Influenza virus neuraminidase is thought to be essential for virus replication in humans; however, to date, available neuraminidase inhibitors are limited to zanamivir, which is topically administered. OBJECTIVE: To determine the safety, tolerability, and antiviral activity of oral neuraminidase inhibitor oseltamivir (GS4104/Ro64-0796) for prevention and the early treatment of influenza in experimentally infected humans. DESIGN: Two randomized, double-blind, placebo-controlled trials conducted between June and July 1997. SETTING: Individual hotel rooms; 2 large US university medical schools. PARTICIPANTS: A total of 117 healthy adult volunteers (aged 18-40 years; median age, 21 years) who were susceptible (hemagglutination-inhibition antibody titer < or =1:8). INTERVENTIONS: All subjects were inoculated intranasally with influenza A/Texas/36/91 (H1N1) virus. For the prophylaxis study, oral oseltamivir (100 mg once daily [n = 12], 100 mg twice daily [n = 12], or matching placebo [n = 13], starting 26 hours before virus inoculation) was administered. For the treatment study, the same drug was given (20 mg, 100 mg, or 200 mg twice daily, 200 mg once daily, or matching placebo [n = 16], in each group starting 28 hours after inoculation). All regimens were continued for 5 days. MAIN OUTCOME MEASURES: Comparing placebo groups with pooled treatment groups, for prophylaxis, outcomes included frequency of infection and viral shedding; for treatment, viral shedding in titers. RESULTS: In the prophylaxis study, 8 (67%) of 12 placebo and 8 (38%) of 21 oseltamivir recipients became infected (P = .16; efficacy, 61%); 6 (50%) placebo compared with 0 oseltamivir recipients shed virus (P<.001; efficacy, 100%), and 33% of placebo but no oseltamivir recipient had infection-related respiratory illness (P<.01). Among infected subjects in the treatment study (n = 69), the viral titer area under the curve of the combined oseltamivir groups (n = 56) was lower (median [interquartile range [IQR]], 80 [23-151] vs 273 [79-306] log10 tissue culture-infective doses50 per milliliter x hour; P = .02) than the placebo group (n = 13), and the median (IQR) duration of viral shedding with therapy was reduced from 107 (83-131) to 58 (35-59) hours (P = .003). Oseltamivir treatment also reduced symptom scores (median [IQR] score-hours, 225 [97-349] vs 400 [189-645]; P = .05), and nasal proinflammatory cytokine levels. Transient mild to moderate nausea after dosing was observed in 15 (17%) of 88 oseltamivir and 2 (7%) of 29 placebo recipients (95% confidence interval for difference, -11% to 68%), which was largely prevented by ingestion with food. CONCLUSIONS: In these trials, prophylaxis and early treatment with oral oseltamivir were both associated with significant antiviral and clinical effects in experimental human influenza.

Administration, Oral↗
PubMed1983

beta-Galactosidase-neuraminidase deficiency (galactosialidosis): clinical, pathological, and enzymatic studies in a postmortem case.

Three male siblings in a Japanese family were affected with beta-galactosidase-neuraminidase deficiency (galactosialidosis). One patient died at 45 years of age, and postmortem liver and brain tissues were studied enzymatically. The residual activity of neuraminidase was relatively high in these tissues. Neuraminidase activity did not change in the tissues after repeated freezing and thawing of the homogenates, whereas this enzyme in control tissues lost 30 to 60% of its activity. There was a profound deficiency of beta-galactosidase in the tissues of the patient. Michaelis constant, pH profiles, and cryostability were identical for the patient and control patients. Cathepsin B was moderately increased in activity in the patient's tissues.

Adult↗
PubMed1982

A comparison of two anti-neuraminidase monoclonal antibodies by complement activation.

The specificities of two anti-neuraminidase monoclonal antibodies have been compared by their ability to fix complement. They were found to differ to some extent in their reactivity with a range of N2 influenza virus. Thus, as in the case of anti-hemagglutinin antibodies, anti-neuraminidase monoclonal antibodies are able to detect subtle structural changes in the vital antigen. Although both monoclonal antibodies fixed complement with intact virus, neither one fixed complement when complexed with isolated neuraminidase "heads".

Animals↗
PubMed2004

Change in relative mobility of M protein following neuraminidase treatment in patients with multiple myeloma and monoclonal gammopathy of undetermined significance.

The aim of this study was to clarify the relationship between the relative mobility of M protein in various disease states using cellulose acetate membrane electrophoresis. To examine the carbohydrate chain of the M protein, sera from patients with multiple myeloma (MM), various cancers, and benign disease were treated with neuraminidase. The relative mobility in benign disease and MM patient sera following neuraminidase treatment varied among individuals, while that of IgG M protein in sera from cancer patients was from 0.2 to 0.3. Thus, the relative mobility in cancer patients was narrower than in those with MM or benign disease.However, after neuraminidase treatment, there was no significant difference between relative mobility in cancer patient's sera and those in other disease patients.

Adult↗
PubMed1983

Ganglioside-basic protein interaction: protection of gangliosides against neuraminidase action.

The ability of acidic phospho- and sphingolipids to interact with basic proteins was studied by double diffusion analysis. The phospholipids, tri- and diphosphoinositide, and the sphingolipid, sulfatide, interacted with myelin basic protein as evidenced by precipitin line formation. Of the sialoglycosphingolipids (gangliosides) tested, only the myelin-specific monosialoganglioside, GM4, formed a precipitin line with myelin basic protein. In addition, myelin basic protein retarded the activity of Clostridium perfringens neuraminidase against GM4 and the disialoganglioside, GD1b. Examination of purified rat brain myelin suggested the presence of a neuraminidase activity intrinsic to myelin. This finding, in concert with ganglioside-myelin basic protein complexes which selectively protect against neuraminidase, may provide a physiological explanation for the simplified ganglioside pattern found in myelin.

Animals↗
PubMed1994

Complete sequence of the Bacteroides fragilis YCH46 neuraminidase-encoding gene.

The nucleotide sequence of the Bacteroides fragilis neuraminidase-encoding gene (nanH) and its flanking regions was determined. The B. fragilis nanH open reading frame (ORF) of 1632 nucleotides encoded a neuroaminidase of 544 amino acid residues with a calculated molecular mass of 59.51 kDa. The amino acid sequence at the N-terminus of the deduced protein exhibited the common features of procaryotic signal sequences. The Asp box sequence, Ser-X-Asp-X-Gly-X-Thr-Trp, which is conserved among bacterial neuraminidases, was found at five positions in the deduced amino acid sequence. A single transcription start point was identified 88 nucleotides upstream of the nanH ORF. Northern blot analysis using an internal nanH probe revealed a single mRNA species with a length of 1.8 kb that could encode just the neuraminidase.

Amino Acid Sequence↗
PubMed1978

Studies on bovine brain membrane-bound neuraminidase (sialidase).

1) Lipophilic ganglioside GD1a (IV3NeuAc, II3NeuAc-GgOse4-Cer) is taken up by the cell membranes and hydrolyzed faster by membrane-bound neuraminidase than are water soluble substrates of the enzyme. 2) The enzymic breakdown of ganglioside GD1a is enhanced by general anesthetics whereas the degradation of the hydrophilic substrate sialyllactitol is reduced by these same agents. 3) General anesthetics lower the microviscosity of membranes as indicated by studies of fluorescence depolarisation with the indicator 1,6-diphenylhexatrien. Decreased microviscosity can result in a higher lateral diffusion of ganglioside GD1a, increasing its interaction with membrane-bound neuraminidase. 4) In vitro studies indicate that the activity of membrane-bound neuraminidase on gangliosides of brain membranes is regulated by the viscosity of these membranes and their monosialoganglioside content.

Animals↗
PubMed1982

Therapeutic effectiveness of neuraminidase-treated allogeneic myeloblasts as immunogen in acute myelocytic leukemia.

Our chemoimmunotherapy study shows significantly longer remission and survival in acute myelocytic leukemia (AML) patients who have been immunized with neuraminidase-treated allogeneic myeloblasts as compared to patients who received chemotherapy alone or neuraminidase-treated myeloblasts plus MER. MER impairs the immunotherapeutic effectiveness of neuraminidase-treated allogeneic myeloblasts in AML patients. The in vivo and in vitro immunologic status in each arm of the protocol correlate well with the duration of remission and survival of the patient.

B-Lymphocytes↗
PubMed1990

Effects of phospholipases, proteases and neuraminidase on gamma-hydroxybutyrate binding sites.

gamma-Hydroxybutyric acid (GHB) is a natural compound of mammalian brain synthesized from GABA. The characteristics of its synthesis, transport, release, distribution and turnover, in addition to the presence of a high affinity binding site for this substance in brain are in favor of a modulator role for GHB. The effects of hydrolytic enzymes on the specific binding capacity of GHB have been studied in the present work. Phospholipases A2 and C, neuraminidase and Pronase markedly decrease GHB binding to crude synaptosomal membranes from rat brain. This effect is time and enzyme concentration dependent. Trypsin, under the conditions employed, is less active. The inhibitory effects of phospholipases is correlated with phospholipid hydrolysis. Lysophospholipids, in the absence of bovine fatty acid free serum albumin partially inhibit GHB binding. The action of neuraminidase has been followed by sialic acid release and modifications of the ganglioside profile. The effects of phospholipase C and of neuraminidase are completely different to those on GABA binding sites. These results represent further data concerning the molecular existence of specific GHB binding sites on rat brain membranes.

Animals↗
PubMed1978

Sequestration of neuraminidase-treated erythrocytes. Studies on its topographic, morphologic and immunologic aspects.

Scintigraphic experiments and radioactivity measurements of tissues have shown that the radioactivity of 51Cr-labelled and neuraminidase-treated rabbit erythrocytes is rapidly accumulated in liver and spleen. Sequestration of these erythrocytes by liver and spleen was demonstrated by light and electron microscopy of theses tissues after perfusion of the rabbits with solutions for tissue fixation. In liver the phagocytic activity of Kupffer cells was increased after injection of desialylated erythrocytes, while in spleen a significantly enhanced number of erythrocytes was found attached to the sinusoidal walls and in the reticulum of the red pulp. It was shown by scanning electron microscopy that neuraminidase-treatment did not influence the shape of erythrocytes. Desialylated and 51Cr-labelled erythrocytes from the cow are rapidly cleared from the blood-stream with a half-life time of about 3 h. It was shown in an in-vitro test that they adsorb to surviving slices from liver and spleen derived from the same animal. The amount of radioactivity adsorbed is appreciably enhanced in the presence of homologous serum when compared with buffer only. Human neuraminidase-treated erythrocytes are agglutinated in the direct and especially in the indirect Coombs-tests. The involvement of T-antigen in this phenomenon was largely excluded. The in vitro experiments and antibody consumption tests suggest that immunoglobulins (IgG) and complement from serum may be involved in recognition and sequestration of desialylated erythrocytes by macrophages in vivo.

Animals↗
PubMed1979

Effects of exogenous neuraminidase on unit activity in frog spinal cord and fish optic tectum.

The effect of exogenous neuraminidase on spontaneous and evoked synaptic activity was investigated following injection of the enzyme into frog spinal cord and into cord and into the carp optic tectum. 1. Injection of enzyme into spinal cord segments caused a significant increase of motoneuron activity in the corresponding spinal nerve, which lasted for 7--31 min. 2. The amplitude of postsynaptic evoked potentials in the optic tectum was increased after neuraminidase injection up to 200% of control level for 20--40 min, whereas the amplitude of summed action potentials of retino-tectal afferents remained unchanged. 3. Similar effects were observed in single cell responses of the optic tectum with some differences in the degree of increase in activity, as well as latency and final depression of the stimulus response. 4. The extent of neuraminic acid liberation following neuraminidase treatment was determined biochemically. In both tissues investigated the amount of free neuraminic acid was increased significantly (4--5.5 fold) after enzyme treatment. Whereas after enzyme injection into spinal cord and optic tectum the percentage release of total glycoprotein- and glycolipidbound neuraminic acid was 12% and 15%, respectively, liberation from enzyme incubated tissue homogenates was somewhat higher (20.5% and 24%).

Animals↗
PubMed1979

Neuraminidase treatment reveals sialic acid differences in certain genetic variants of the Gc system (vitamin-D-binding protein).

Common and rare Gc phenotypes were analyzed by agarose gel electrophoresis immunofixation and by isoelectric focusing immunofixation before and after neuraminidase treatment. There is a difference between Gc types with double-band and with single-band patterns. Neuraminidase affects only Gc types with a double-band pattern: The double-band pattern is reduced to a single-band pattern. The anodal band disappears after removal of sialic acid by enzymatic cleavage; the cathodal band remains unchanged in its position and becomes stronger. Single-band Gc phenotypes remain unaltered after neuraminidase treatment.

Carrier Proteins↗