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)

Acid mucins in goblet cells of the duodenum, jejunum and ileum of neonates and infants with cystic fibrosis (CF) and without CF were measured by scanning microdensitometry after alcian blue staining according to the protocol of McCarthy and Reid (1963) which characterises four groups of acidic mucins. In CF infants over 6 mth of age, but not in controls, there was an increase along the gut from duodenum to ileum of both weakly acidic and strongly acidic sulphomucins. In the ileum the increase was in total mucins from 6 mth previously in the same CF patients and this difference could be accounted for by an increase of sialidase-resistant mucins. The increase in sulphomucins was more marked at the tip than at the base of the villi. In CF neonates there was significant difference in the quantities of acidic mucins. The question whether the mucins of CF are chemically abnormal or merely accumulated to an abnormal extent is probably best investigated by analysis of sialidase-resistant mucins and sulphomucins of the ileum and strongly acidic sulphomucins of the duodenum and jejunum in CF infants over 6 mth of age.
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PMID:Acid mucins in human intestinal goblet cells. 74 14

The exotoxin produced by Vibrio cholerae is rapidly and firmly bound to the outer membrane of mammalian cells. With simple in vitro and in vivo methods and very pure gangliosides and allied glycolipids we have demonstrated that the monosialosylganglioside GM1 is the natural receptor for the cholera toxin. This ganglioside binds the toxin with a high affinity and inactivates it. The inactive derivative, choleragenoid toxoid has the same affinity to GM1 as the toxin. Ganglioside GM1 was isolated from the small intestinal mucosa of man, pig and ox in amounts of 0.1, 2.0 and 43 nmoles per g mucosa, respectively. These very large differences in the ability of the mucosal cells to bind cholera toxin. Exogenous GM1 was incorporated in vitro and in vivo in intestinal mucosal cells. The incorporation of GM1 increased the number of toxin-binding sites and increased the secretion of fluid in the gut. Vibrio cholerae sialidase did not hydrolyse the di- and trisialogangliosides of intact mucosal cells to the parent GM1-ganglioside, neither did it increase the number of cholera toxin-binding sites.
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PMID:Interaction of cholera toxin and ganglioside G(M1). 93 47

Blood-borne lymphocytes initiate entry into secondary lymphoid organs, such as peripheral lymph nodes (PN) and gut-associated Peyer's patches (PP), by a highly specific adhesive interaction between the lymphocytes and the endothelium of specialized blood vessels known as a high endothelial venules (HEV). The selectivity with which functional subpopulations of lymphocytes migrate into particular lymphoid organs is believed to be regulated by the expression of cell adhesion receptors and complementary ligands on lymphocytes and HEV, respectively. The entry of lymphocytes into PN and PP has clearly been shown to involve distinct receptor-ligand pairs. Employing the Stamper-Woodruff in vitro adhesion assay, which measures lymphocyte attachment to HEV in cryostat-cut sections of lymphoid organs, we have previously shown that treatment of PN sections with two different sialidases inactivates HEV-adhesive ligands, whereas treatment of PP tissue sections has no effect on HEV-adhesive function. We now report that in vivo exposure of HEV to sialidase (after i.v. injection of the enzyme) also selectively prevents subsequent in vitro attachment of lymphocytes to PN HEV but not to PP HEV. Consistent with this organ-selective impairment of HEV-adhesive function by sialidase, i.v. injection of the enzyme is shown to prevent short term lymphocyte accumulation within peripheral lymph nodes while having no significant effect on accumulation in PP, blood, or nonlymphoid organs. Histologic examination with the sialic acid-specific lectin from Limax flavus verified that i.v. injected sialidase effectively removes stainable sialic acid moieties from HEV in both PN and PP. This study confirms that sialic acid is required for the adhesive function of PN HEV-ligands. A role for sialic acid as either a recognition determinant or as a regulatory molecule can be envisioned. In view of the fact that many pathogens release sialidase and cause substantially elevated serum levels of this enzyme, the present observations may have pathophysiologic significance. One mechanism by which such pathogens may avoid destruction is to inactivate susceptible HEV-ligands and disrupt the entry of lymphocytes into lymphoid organs where immune responses against the pathogens would normally be initiated.
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PMID:Intravenously injected sialidase inactivates attachment sites for lymphocytes on high endothelial venules. 292 20

During the course of their recirculation through the body, blood-borne lymphocytes specifically adhere to high endothelial venules (HEV) within secondary lymphoid organs such as peripheral lymph nodes (PN) and gut-associated Peyer's patches (PP). This adherence event, which initiates the extravasation of the lymphocyte, is highly specific in terms of the class of lymphocyte and the anatomic location of the HEV. We review evidence that the lymphocyte adhesive molecule ('homing receptor') involved in attachment to PN HEV is a carbohydrate-binding receptor (lectin-like) with specificity for mannose-6-phosphate (M6P)-like ligands. We describe the use of a novel cytochemical probe for the detection and characterization of cell surface carbohydrate-binding receptors. Using a M6P-based probe, we show that the carbohydrate-binding receptor on lymphocytes is closely-related or identical to the MEL-14 antigen, a putative homing receptor identified by a monoclonal antibody. Evidence is presented that the lymphocyte attachment sites on both PN and PP HEV are inactivated by mild periodate oxidation and hence are probably carbohydrate in nature. Yet, the sites are biochemically distinguishable in that one class (PN) requires sialidase-sensitive structures whereas the other (PP) does not. We raise the possibility that diversity in the carbohydrate-based recognition determinants on HEV may underlie the adhesive specificities in this system.
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PMID:Lymphocyte attachment to high endothelial venules during recirculation: a possible role for carbohydrates as recognition determinants. 302 59

Recent work indicates that subpopulations of human fecal bacteria, averaging approximately 1% of the total viable fecal flora, degrade the oligosaccharide side chains of hog gastric mucin, which structurally resembles human epithelial mucins. Here we report studies to determine whether degradation of mucin oligosaccharides is related to glycosidase production by bacteria growing in anaerobic fecal cultures. Triplicate cultures containing hog gastric mucin were inoculated with serially diluted feces from each of seven healthy subjects. When the stationary growth phase was attained, mucin oligosaccharide degradation and both cell-bound and extracellular activities of four glycosidases were measured in each culture. Cell-bound beta-d-galactosidase, beta-N-acetylglucosaminidase, and sialidase were present in bacteria growing at all levels of fecal inocula, including 10(-11) g. In contrast, extracellular activities were present in every culture inoculated with 10(-4)-10(-7) g feces, but were diminished or absent in cultures inoculated with 10(-8)-10(-11) g feces. Bacterial autolysis was an unlikely cause of extracellular glycosidase activity, since p-nitrophenyl-alpha-l-fucosidase remained cell bound in cultures at every level of fecal inoculum. Degradation of mucin oligosaccharides was associated with extracellular, but not with cell-bound beta-d-galactosidase, beta-N-acetylglucosaminidase, and sialidase. Among the seven subjects, the estimated most probable numbers (MPN) of fecal bacteria producing extracellular beta-d-galactosidase, beta-N-acetylglucosaminidase, and sialidase ranged from 10(6)-10(10)/g dry fecal wt, were comparable to the MPN of mucin-degrading bacteria, and were significantly smaller than the MPN of total fecal bacteria. We interpret these findings as evidence for the existence of bacterial subpopulations in the normal fecal flora that produce extracellular glycosidases, and that these subpopulations have a major role in degrading the complex oligosaccharides of mucin in the gut lumen.
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PMID:Mucin degradation in human colon ecosystems. Evidence for the existence and role of bacterial subpopulations producing glycosidases as extracellular enzymes. 616 Nov 36

Trypanosoma cruzi expresses a unique trans-sialidase that is responsible for the transfer of sialic acid from host glycoproteins and glycolipids to mucin-like glycoprotein acceptors on the parasite surface. The enzyme and the sialic acid acceptors are present in the mammalian forms of the parasite and in the parasite forms that grow in axenic cultures, which correspond to the developmental stages found in the insect vectors. Here we show that parasite forms growing in the vector Triatoma infestans express trans-sialidase in the hindgut portions of the insect. However, the sialic acid acceptors are poorly sialylated due to the low concentration of sialic acid donors in the gut lumen of T.infestans, which feeds exclusively on blood that is rich in sialic acid donors. These low levels of sialic acid donors are due to a novel sialidase activity present mainly in the anterior midgut with high specificity for alpha-2,3-sialyllactose, but not for alpha-2,6-sialyllactose. The activity is present in starved insects or insects fed with culture medium, indicating that it did not originate from the blood meal. Enzyme activity does not decrease in insects fed with antibiotics, is present in the salivary glands, and the few bacteria isolated from the gut and faeces of T.infestans did not display sialidase activity, indicating that the enzyme is not derived from a commensal organism. This novel activity could have a nutritional role in the gut of haematophagous insects and indicates that acquisition of sialic acid is not required for parasite development in the gut of T.infestans.
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PMID:A sialidase activity in the midgut of the insect Triatoma infestans is responsible for the low levels of sialic acid in Trypanosoma cruzi growing in the insect vector. 856 50

Sialidases (EC 3.2.1.18) are commonly found in viruses, bacteria, fungi, protozoa, and vertebrates, but not in invertebrates. We have previously reported the presence of a new sialidase activity in the gut of exclusively hematophagous insects of the Triatoma genus, which transmit Chagas' disease (Amino, R., Acosta, A., Morita, O. M., Chioccola, V. L. P., and Schenkman, S. (1995) Glycobiology 5, 625-631). Here we show that this sialidase is present in the salivary gland of Triatoma infestans, and it is released with the saliva during the insect bite. The sialidase was purified to homogeneity (>5000 times) to a specific activity of more than 20 units/mg. It elutes from a gel filtration column with a volume corresponding to the size of 33 kDa, and it migrates as a single 26-kDa band in SDS-polyacrylamide gel electrophoresis, which is unusually smaller when compared with other known sialidases. T. infestans sialidase hydrolyzes preferentially alpha2-->3-linked sialic acids at pH 4-8, with maximal activity between pH 5.5 and 6.5, which is compatible with the optimal pH of secreted sialidases. The sialidase is competitively inhibited by 2-deoxy-2, 3-dehydro-N-acetyl-neuraminic acid (Ki = 0.075 mM) and differently from many sialidases, with exception of Salmonella typhimurium sialidase, it is inhibited competitively by HEPES (Ki = 15 mM). The fact that T. infestans sialidase is released with the saliva and can hydrolyze sialyl-LewisX blood groups, which are the ligands for selectins, suggests that it might have a role in the blood feeding.
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PMID:Identification and characterization of a sialidase released by the salivary gland of the hematophagous insect Triatoma infestans. 973 52

Blastocrithidia culicis and Crithidia deanei are trypanosomatid protozoa of insects that normally contain intracellular symbiotic bacteria. The protozoa can be rid of their endosymbionts by antibiotics, producing a cured cell line. Here, we analyzed the glycoconjugate profiles of endosymbiont-harboring and cured strains of B. culicis and C. deanei by Western blotting and flow cytometry analyses using lectins that recognize specifically sialic acid and mannose-like residues. The absence of the endosymbiont increased the intensity of the lectins binding on both trypanosomatids. In addition, wild and cured strain-specific glycoconjugate bands were identified. The role of the surface saccharide residues on the interaction with explanted guts from Aedes aegypti gut was assessed. The aposymbiotic strains of B. culicis and C. deanei presented interaction rates 3.3- and 2.3-fold lower with the insect gut, respectively, when compared with the endosymbiont-bearing strains. The interaction rate of sialidase-treated cells of the wild and cured strains of B. culicis and C. deanei was reduced in at least 90% in relation to the control. The interaction of B. culicis (wild strain) with explanted guts was inhibited in the presence of mucin (56%), fetuin (62%), sialyllactose (64%) and alpha-methyl-D-mannoside (80%), while in C. deanei (wild strain) the inhibition was 53%, 56%, 79% and 34%, respectively. Collectively, our results suggest a possible involvement of sialomolecules and mannose-rich glycoconjugates in the interaction between insect trypanosomatids and the invertebrate host.
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PMID:Influence of the endosymbiont of Blastocrithidia culicis and Crithidia deanei on the glycoconjugate expression and on Aedes aegypti interaction. 1621 41

Sialidases remove sialic acid residues from various sialo-derivatives. To gain further insights into the biological roles of sialidases in vertebrates, we exploited zebrafish (Danio rerio) as an animal model. A zebrafish transcriptome- and genome-wide search using the sequences of the human NEU polypeptides as templates revealed the presence of seven different genes related to human sialidases. neu1 and neu4 are the putative orthologues of the mammalian sialidases NEU1 and NEU4 respectively. Interestingly, the remaining genes are organized in clusters located on chromosome 21 and are all more closely related to mammalian sialidase NEU3. They were thus named neu3.1, neu3.2, neu3.3, neu3.4 and neu3.5. Using RT-PCR (reverse transcription-PCR) we detected transcripts for all genes, apart from neu3.4, and whole-mount in situ hybridization experiments show a localized expression pattern in gut and lens for neu3.1 and neu4 respectively. Transfection experiments in COS7 (monkey kidney) cells demonstrate that Neu3.1, Neu3.2, Neu3.3 and Neu4 zebrafish proteins are sialidase enzymes. Neu3.1, Neu3.3 and Neu4 are membrane-associated and show a very acidic pH optimum below 3.0, whereas Neu3.2 is a soluble sialidase with a pH optimum of 5.6. These results were further confirmed by subcellular localization studies carried out using immunofluorescence. Moreover, expression in COS7 cells of these novel zebrafish sialidases (with the exception of Neu3.2) induces a significant modification of the ganglioside pattern, consistent with the results obtained with membrane-associated mammalian sialidases. Overall, the redundancy of sialidases together with their expression profile and their activity exerted on gangliosides of living cells indicate the biological relevance of this class of enzymes in zebrafish.
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PMID:Molecular cloning and biochemical characterization of sialidases from zebrafish (Danio rerio). 1770 49

The molecular basis by which human breast milk supports the development of a protective intestinal microbiome in infants is unknown. After lactose and lipids, human milk oligosaccharides (HMOs) are quantitatively the third largest and most diverse component of breast milk. In this work, glycomic profiling of HMO consumption by bifidobacteria using Fourier transform ion cyclotron resonance mass spectrometry reveals that one species, Bifidobacterium longum biovar infantis ATCC 15697, an isolate from the infant gut, preferentially consumes small mass oligosaccharides, representing 63.9% of the total HMOs available. These HMOs were detected in human breast milk at the onset and constantly through the first month of lactation by use of high performance liquid chromatography-chip time-of-flight mass spectrometry. Further characterization revealed that strain ATCC 15697 possesses both fucosidase and sialidase activities not present in the other tested strains. This work provides evidence that these small mass HMOs are selectively metabolized by select bifidobacterial strains and represent a potential new class of bioactive molecules functioning as prebiotics to facilitate a protective gut colonization in breast-fed newborns.
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PMID:Glycoprofiling of bifidobacterial consumption of human milk oligosaccharides demonstrates strain specific, preferential consumption of small chain glycans secreted in early human lactation. 1791 60


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