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)

Fragment 1, released from bovine plasma high-molecular-weight kininogen by the action of plasma kallikrein, is a glycopeptide with approximately 3 mol of each of N-acetylgalactosamine, galactose and sialic acid in one molecule. All these sugars were in the T-1 fragment obtained by tryptic digestion of fragment 1. Sialic acid can be completely released from the T-1 fragment by sialidase digestion. When this sialic acid-free T-1 fragment was incubated with purified diplococcal endo-alpha-N-acetylgalactosaminidase, all remaining sugars were released as a disaccharide. By Smith degradation and beta-galactosidase digestion, the structure of this disaccharide was found to be Gal beta 1 leads to 3GalNAc. Methylation analysis of the trisaccharide released from fragment T-1 by alkaline borohydride treatment indicated that all the galactose was obtained as the 2,4,6-tri-O-methyl derivative. Based on this evidence, the complete structure of the carbohydrate moieties of fragment 1 was proposed as Sialyl alpha 2 leads to 3Gal beta 1 leads to 3GalNAc. In addition, small amounts of a tetrasaccharide, Sialyl alpha 2 leads to 3Gal beta 1 leads to 3(Sialyl alpha 2 leads to 6)GalNAc also occurred as a carbohydrate chain of fragment 1.
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PMID:The carbohydrate structure of a glycopeptide released by the action of plasma kallikrein on bovine plasma high-molecular-weight kininogen. 91 96

The specificity of the anti A+N lectin of Moluccella laevis (MLL) was examined by hemagglutination experiments with enzyme-modified human erythrocytes and by inhibition of hemagglutination. In addition, binding to various glycoproteins and inhibition by different sugars and glycoproteins were examined by enzyme immunoassay with antibodies to the lectin. Treatment of AMM erythrocytes with proteolytic enzymes increased their agglutinability by MLL 4-16-fold; similar treatment of ONN cells decreased their agglutinability 8-16-fold. This is in line with the known location and enzyme sensitivity of A and N specificity determinants. Treatment of the erythrocytes with sialidase increased their agglutinability and abolished the distinction between N and M cells. Hapten inhibition of hemagglutination of AMM and ONN erythrocytes by the lectin, and its binding to glycoproteins measured by enzyme immunoassay, confirmed the high specificity of MLL for N-acetyl-D-galactosamine (200-500 times more than for D-galactose) and suggested the presence of hydrophobic interactions around HO-2 of the D-galactose unit. The methyl alpha-glycosides of D-galactose and of N-acetyl-D-galactosamine were better inhibitors than the corresponding beta-glycosides; this preference was abolished, and sometimes reversed, when the p-nitrophenyl glycosides of the same monosaccharides were tested, stressing again the importance of hydrophobic interactions in the binding of carbohydrates to MLL. The lectin reacted well with ONN substance and with glycophorin A of the N phenotype (GPAN), but did not react with OMM substance or GPAM. The strongest inhibitor was asialo ovine submaxillary mucin, which contains many unsubstituted alpha-D-GalpNAc-(1-->3)-Ser/Thr residues; calculated per N-acetyl-D-galactosamine residue, it was 1500 stronger than free N-acetyl-D-galactosamine. In accordance with this result, it was found that the lectin strongly agglutinates Tn cells. The specificity of MLL can, thus, be defined as anti-Tn, crossreactive with blood types A and N, and with sialosyl-Tn. The N-specificity can best be explained by assuming that GPAN contains a small number of unsubstituted or partially sialylated alpha-D-GalpNAc-(1-->3)-Ser/Thr residues, which are present in smaller proportions, if at all, in GPAM.
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PMID:Immunochemical studies on the combining site of the A + N blood type specific Moluccella laevis lectin. 129 Oct 50

The cDNA coding for pre-peanut agglutinin (PNA) was isolated from a bacterial expression library. It codes for a polypeptide of 273 amino acids composed of a hydrophobic signal peptide of 23 amino acids and a mature protein of 250 amino acids. The sequence of the latter is identical to that of native PNA, determined very recently by conventional methods, except that it contains 14 additional amino acids at the C-terminus. Bacterial cells harboring a plasmid with the prePNA-cDNA, produced two PNA cross-reacting proteins: one migrated on SDS-PAGE identically with the native lectin (apparent mol. wt. 31 kDa); the other, at 35 kDa, was a beta-galactosidase pre-PNA fusion protein. The former protein possessed an N-terminal sequence identical to that of the mature, native PNA, suggesting that it was processed from the 35 kDa prePNA precursor. Only the 31 kDa protein was exported into the bacterial periplasmic space, and had the ability to bind to galactose-Sepharose. The isolated processed protein had the same hemagglutinating activity as the native lectin, when assayed with sialidase-treated human erythrocytes. Like the native lectin, it did not agglutinate the untreated cells, was not inhibited by N-acetylgalactosamine, and was inhibited by Gal beta 1----3GalNAc 30-times more strongly than by galactose.
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PMID:Cloning, sequence analysis and expression in Escherichia coli of the cDNA encoding a precursor of peanut agglutinin. 133 58

Sugar specific lectins (PNA, RCA I, LPA, SBA, DBA, GSA IB4, GSA II, WGA, LTA, UEA I, Con A, LCA) with and without prior selective glycosidase digestion (sialidase, alpha-fucosidase, alpha-mannosidase, beta-N-acetylglucosaminidase, alpha- and beta-galactosidase, beta-glucosidase) were used in order to investigate the distribution of native accessible carbohydrates and obtain information dealing with the composition of terminal disaccharides within glycoconjugates present in acinar compartments and ductal segments of mammalian (mouse, rat, hare, and rabbit) parotid glands. Glycoconjugates containing variable amounts of mannose, glucose, N-acetylgalactosamine and N-acetylglucosamine were present in the parotid glands of all species. However, these carbohydrate chains exhibited a different composition of terminal sequences within each type of gland. For example, sialylated components having the terminal dimers sialic acid-galactose and sialic acid-N-acetylgalactosamine were found in all acinar cells, whereas fucoglycoconjugates with terminal disaccharide fucose-galactose were localized in the rat striated ducts and hare acinar cells. The terminal sequence alpha-galactose-beta-galactose was demonstrated in the mouse acinar cells. Finally, glycoconjugates characterized by the terminal dimer beta-galactose-N-acetylgalactosamine were demonstrated in the mouse acinar and ductal cells and the rat ductal ones. Thus, present findings outlined and further confirmed the possibility to elucidate the oligosaccharide structure in situ using lectin histochemistry combined with enzymatic degradation.
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PMID:Glycoconjugate composition of mammalian parotid glands elucidated in situ by lectins and glycosidases. 137 7

The preparation of greater than 30 different hybridomas, all secreting IgM class antibodies against epiglycanin, a glycoprotein at the surface of the mouse mammary carcinoma cell line TA3-Ha, is described. The specificities of 10 of the antibodies, with affinity constants in the range of 10(8)-10(10) l/mol were compared in an enzyme competitive binding assay. The affinity of epiglycanin was strongly reduced for all antibodies tested by incubation with periodate (10 mM, 4 degrees C) and was reduced for most of the antibodies by endo-alpha-N-acetyl- D-galactosaminidase. This suggested that carbohydrate, and specifically the Gal beta (1----3)GalNAc disaccharide, formed an integral part of the epitopes of most of the antibodies. The isolated disaccharide, however, exhibited 250,000 times less inhibitory activity in the competitive binding assay than epiglycanin. The binding capacity of epiglycanin was also reduced by incubation with trypsin or pronase, suggesting a high molecular weight dependency for binding. Incubation with sialidase increased its affinity for the antibodies. The binding of the antibodies to epiglycanin was strongly inhibited by peanut agglutinin, and to a lesser extent by lectins from Triticum vulgaris, Ricinus communis, Pisum sativum and Phaseolus vulgaris. None of the antibodies bound to any of eight different gangliosides immobilized on HPTLC plates. Mono- (Fab) and divalent [F(ab')2] fragments of the antibodies possessed very low affinity for epiglycanin. The results demonstrated that the specificities of the antibodies are related, but distinguishable, and they suggest that this epiglycanin-IgM model may be useful for studies on the general principles of the interaction between IgM antibodies and mucin-type glycoproteins.
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PMID:Development and characterization of monoclonal antibodies against a mucin-type glycoprotein. 149 19

We employed sialidase procedures followed by lectin stainings combined with oxidizing and deacetylating agents to visualize the distribution and sequentiate sialoglycoconjugates in the bovine submandibular gland. In particular we evidenced in acinar and ductal cells the dishomogeneous presence of sialic acids acetylated in the polyhydroxy side chain (C7, C8, C9), whereas O-acetyl substituents at position C1 and/or C4 were not found. Sialoglycoderivatives were also differentiated by the occurrence of penultimate sugars; indeed the dimers sialic acid-(alpha 2----3,6)-beta-galactose and sialic acid-(alpha 2----6)-alpha-N-acetylgalactosamine were identified. Using such technique we supported further the possibility to develop methods for the identification of the positions of O-acetyl groups and the reconstruction of terminal disaccharides within surface and cytoplasm glycoconjugates. in situ the distribution of different O-acylated sialoglyco-derivatives in the bovine submandibular gland. To this purpose we employed oxydizing and deacetylating agents combined with sialidase digestion and lectin binding.
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PMID:Sialoglycoderivatives of bovine submandibular gland identified in situ by histochemical techniques combined with lectins. 150 Feb 95

Total saliva and secretions from parotid and submandibular glands of patients with carcinomas in the oral cavity, oropharynx or larynx and a control group of healthy individuals were analyzed for concentrations of glycosidically bound sugars and free N-acetylneuraminic acid as well as for sialidase activity. When compared to the data obtained for normal donors, the relative amounts of the individual monosaccharides fucose, galactose, mannose, N-acetylgalactosamine, and N-acetylglucosamine as components of glycoconjugates showed variable differences to the group of tumor patients depending on the type of secretion and the location of the tumor. The percentage of glycosidically linked N-acetylneuraminic acid, however, was always higher for the healthy donors. A significant difference was found in the amount of free sialic acid, with the exception of submandibular gland secretion from a patient with an oropharyngeal carcinoma, and sialidase activity which were increased for tumor patients, independent of the type of secretion and the location of the tumor. From these results it is concluded that free sialic acid and sialidase activity may be considered as markers for carcinomas in the upper aerodigestive tract.
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PMID:Analysis of carbohydrate composition and sialidase activity in oral secretions of patients with tumors in the upper aerodigestive tract. 156 17

The relationship between cell differentiation/tumorisation and plasma membrane glycoproteins was approached using peanut agglutinin (PNA) a lectin specific for the Gal-beta(1,3)GalNAc sequence and a homologous cell system consisted of normal rat hepatocytes (HyC) and a poorly differentiated hepatoma (ZHC). This work is focused on the molecular nature of PNA receptors. PNA bound strongly to ZHC, but bound very weakly, if at all to hepatocytes. After sialidase treatment this binding was slightly enhanced in ZHC and HyC. The total number of binding sites on ZHC was 9.6 x 10(6)/cell and 1.2 x 10(7)/cell before and after sialidase treatment respectively. In contrast, this number could not be calculated on HyC, even after sialidase treatment. The PNA receptors were isolated and identified from ZHC using affinity chromatography on immobilized PNA and lectin overlay. Two bands were revealed after SDS-PAGE of PNA receptors: a major one with a relative molecular mass of 160 kDa and a minor one of 110 kDa. The latter disappeared after sialidase treatment of ZHC suggesting the possibility that these two bands could be less and more sialylated forms of the PNA receptors, respectively. In contrast no PNA receptors could be detected on HyC. These PNA receptors could be considered O-linked glycoproteins containing the Gal-beta(1,3)GalNAc disaccharide because: i) PNA carbohydrate specificity toward this disaccharide found in this glycoprotein type; ii) their carbohydrate composition with Gal and GalNAc but not man residues; iii) their sensitivity to alkaline treatment; and iv) strong inhibition of PNA binding to ZHC with the Gal-beta(1,3)GalNAc structure. The absence of PNA receptors on HyC appeared to be related to the absence of this glycoprotein containing the disaccharide but not to the change or failure of glycosylation of the polypeptide chain of PNA receptors. The relationship between the presence of PNA receptors and differentiation/tumorisation phenomena as well as the mechanism that induced the expression of these receptors are discussed.
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PMID:Identification of peanut agglutinin receptors related to the state of tumoral liver cell differentiation. 157 2

Two glycoproteins were isolated from lysates of thioglycollate-stimulated, murine peritoneal macrophages by affinity chromatography on immobilized Griffonia simplicifolia I lectin and by preparative SDS/PAGE. The glycoproteins were readily labeled on the surface of intact macrophages with 3H and 125I. The labeled glycoproteins migrated as broad bands of molecular mass 92-109 kDa and 115-125 kDa. The mobility of the glycoproteins decreased only slightly after reduction with dithiothreitol, indicating the absence of intersubunit disulfide bridges. The 92-kDa and 115-kDa glycoproteins had pI 5.2-5.4 and pI less than or equal to 4, respectively. Digestion of both glycoproteins with alpha-galactosidase released 23% of their 3H content and abolished their ability to bind to the G. simplicifolia I lectin, showing that they contain terminal alpha-D-galactosyl groups. After reduction with 2-mercaptoethanol, each glycoprotein fraction was sensitive to N-glycanase; the 115-kDa glycoproteins produced a smear with the front at approximately 67 kDa, whereas the 92-kDa glycoprotein gave two bands of 61 kDa and 75 kDa. Unreduced glycoproteins were insensitive to N-glycanase, suggesting the presence of intramolecular disulfide bonds. Although each glycoprotein fraction was sensitive to endoglycosidase H, this enzyme produced only slight changes in molecular mass when compared with N-glycanase. From these results as well as from the specificity of the enzymes involved, it is concluded that each glycoprotein fraction contains complex-type oligosaccharides and a small amount of high-mannose and/or hybrid-type oligosaccharides. While each glycoprotein fraction was bound to Datura stramonium lectin, they failed to react with anti-[i-(Den)] serum and their digestion with endo-beta-galactosidase did not cause a band shift in SDS/PAGE. Taken together, these results suggest the presence of N-acetyllactosamine units which are not arrayed in linear form but occur as single units, bound either to C2 and C6, or to C2 and C4, or both, of outer mannosyl residues on complex-type oligosaccharides. The glycoprotein(s) fraction precipitated with anti-[I (Step)] serum, suggesting the presence of branched lactosaminoglycans. Digestion of both glycoprotein fractions with a mixture of sialidase and O-glycanase did not alter their mobility in SDS/PAGE, suggesting a lack or low content of O-linked trisaccharides and tetrasaccharides. Each glycoprotein fraction was bound specifically to Sambucus nigra and Maackia amurensis immobilized lectins, indicating the presence of sialic acid linked alpha 2,6 to subterminal D-galactose or N-acetylgalactosamine residues, and alpha 2,3 to N-acetyllactosamine residues, respectively.
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PMID:alpha-D-galactose-bearing glycoproteins on the surface of stimulated murine peritoneal macrophages. Biochemical and immunochemical characterization of purified glycoproteins. 158 69

Borrelia burgdorferi glycoconjugates with different oligosaccharide structures were characterized by a blotting technique with peroxidase-labelled lectins. The localization of surface carbohydrates was studied using electron microscopy with lectin-gold complexes. A high-mannose glycan structure was detected in 83 kDa glycoprotein (major extracellular protein); at least four carbohydrates (glucose or mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine) were present in other Borrelia glycoconjugates. N-acetylneuraminic (sialic) acid was detected on the Borrelia surface. Two sialidases with different specificities were used in an attempt to cleave off the Borrelia N-acetylneuraminic acid. The attempt was successful by using Vibrio cholerae sialidase which has a broad substrate specificity, while the mumps-virus sialidase with restricted substrate specificity had no effect. Endogenous activity of N-acetylneuraminidase was not demonstrated in B. burgdorferi K 5 and B 31 strains.
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PMID:Characterization of Borrelia burgdorferi glycoconjugates and surface carbohydrates. 161 Dec 4


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