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)

Sialophorin (CD43) is the major surface mucin on many hematopoietic cells. It has been implicated in regulating the survival of T lymphocytes in the circulation, and its functions in vitro as the receptor of a T lymphocyte and monocyte activation pathway. The structure of CD43 was examined by protease treatment of lymphoblastoid cells bearing surface CD43. Trypsin treatment converts CD43 (apparent Mr 115,000) to species of apparent Mr 100,000 called T-100, which remains cell-associated; however, the mechanism of trypsin action was not clarified. Pancreatic elastase and Staphylococcus aureus V8 protease cleave CD43 at discrete extracellular sites. V8 protease generates two fragments, which together account for all properties and mass of the parent molecule. The COOH-terminal fragment V-90 (apparent Mr 90,000) consists of the intracellular and transmembrane regions and part of the extracellular region. The fragment V-30 (apparent Mr 30,000), which is released from the cell, comprises the NH2-terminal approximately 78 amino acids with attached oligosaccharides. V-30 contains the binding sites for the antibodies L2 and L10; the latter is the antibody that activates lymphocytes and monocytes. These findings subdivide the extracellular region of CD43 and indicate that the activation-inducing epitope is located in the most distal portion of the molecule. It is shown that CD43 is insensitive to all but very high concentrations of three proteases. Pretreatment with sialidase enhances sensitivity 13-fold for trypsin, 40-fold for S. aureus V8 protease, and 400-fold for elastase, suggesting that sialic acid influences the survival of surface CD43 molecules when cells are exposed to protease.
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PMID:Proteolytic fragmentation of sialophorin (CD43). Localization of the activation-inducing site and examination of the role of sialic acid. 223 Jan 23

Two cases of an aggressive cutaneous carcinoma showed both squamous and adenomatous differentiation. These neoplasms invaded subcutaneous structures with a sclerosing pattern, making surgical resection difficult. Unlike the usual squamous carcinoma, glands and epithelial mucin (sialomucin) were produced. This mucin stained with mucicarmine and was sensitive to sialidase and resistant to hyaluronidase digestion. No mucin with similar histochemical properties was found in a study of 50 consecutive cutaneous squamous carcinomas and 50 consecutive basal cell epitheliomas from our files. Literature reports of histologically similar cutaneous carcinomas together with our experience with these two cases suggest aggressive behavior for this category of neoplasm.
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PMID:Adenosquamous carcinoma of the skin. An aggressive mucin- and gland-forming squamous carcinoma. 240 85

The nature of the receptor-destroying enzyme (RDE) of influenza C virus has been elucidated by analyzing its effect on the haemagglutination inhibitors rat alpha 1-macroglobulin (RMG) and bovine submandibulary mucin (BSM), respectively. The inhibitory activity of both compounds is abolished by incubation with influenza C virus. After inactivation, RMG and BSM were found to contain reduced amounts of N-acetyl-9-O-acetylneuraminic acid (Neu5,9Ac2) and increased amounts of N-acetylneuraminic acid (Neu5Ac). H.p.l.c. analysis revealed that purified Neu5,9Ac2 is converted to Neu5Ac by incubation with influenza C virus. These results demonstrate that RDE of influenza C virus is neuraminate-O-acetylesterase [N-acyl-9(4)-O-acetylneuraminate O-acetylhydrolase (EC 3.1.1.53)]. The data also indicate that haemagglutination-inhibition (HI) by RMG and BSM and most likely virus attachment to cell surfaces involves binding of influenza C virus to Neu5,9Ac2.
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PMID:The receptor-destroying enzyme of influenza C virus is neuraminate-O-acetylesterase. 241 39

Two monoclonal antibodies, NCC-LU-35 and NCC-LU-81, have been established after immunization of mice with membrane preparations of human lung cancer Lu65 tumor xenograft cells grown in vivo and intact cells cultured in vitro, respectively. These two antibodies react specifically with a majority of human adenocarcinomas, irrespective of the host's blood group ABO status, as well as with normal tissues and erythrocytes of blood group A individuals. The antigenicity is associated with a high molecular weight mucin-like glycoprotein separated by gel filtration of Lu65 tumor extracts. The epitope of the mucin-like glycoprotein has been identified as alpha-N-acetylgalactosaminyl residue directly linked O-glycosidically to serine or threonine residues of polypeptides. This epitope was serologically detected several years ago and given the name Tn. Our identification of the epitope is based on the following results: The antigen is sensitive to alpha-N-acetylgalactosaminidase, but not to sialidase or alpha-fucosidase. Various mono- and difucosyl A determinants, either type 1 or type 2 chain, cross-react with both antibodies. The reactivity with both antibodies can be created by treatment of glycophorin A of normal erythrocytes with sialidase followed by beta-galactosidase. N-[3H]acetylgalactosamine can be released by galactose oxidase/NaB3H4 treatment from the Lu65 mucin-like glycoprotein but not from the mucin-like glycoprotein of normal colonic mucosa upon reductive beta-elimination (alkaline borohydride treatment). The antigen may be one of the tumor-associated A cross-reacting antigens occurring in a wide variety of human adenocarcinomas of hosts belonging to all ABO blood groups.
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PMID:Blood group A cross-reacting epitope defined by monoclonal antibodies NCC-LU-35 and -81 expressed in cancer of blood group O or B individuals: its identification as Tn antigen. 241 56

Bacterial neuraminidases destroy influenza C virus receptors of chick erythrocytes and inactivate hemagglutination inhibitors: rat alpha 1-macroglobulin (RMG) and bovine submaxillary mucin (BSM). These data indicate that neuraminic acid may be a component of influenza C virus receptor. The inhibiting activity of RMG and BSM is also eliminated by the receptor-destroying enzyme (RDE) of influenza C virus. After inactivation, the inhibitors (RMG and BSM) contain a reduced amount of N-acetyl-9-0-acetylneuraminic acid (Neu5, 9Ac2) and a larger amount of N-acetylneuraminic acid (Neu5 Ac). Transformation of Neu5, 9Ac2 into Neu5 Ac may also occur upon incubation of free neuraminic acid with influenza C virus. These data indicate that the RDE of influenza C virus is neuraminate-O-acetylesterase (N-acyl-9 4-O-acetylneuraminate O-acetylhydrolase (EC 3.1.1.53). It was shown that inhibition of influenza C virus hemagglutination by RMG and BSM and, apparently, adhesion of the virus to the cell surface involves binding of influenza C virus with Neu5, 9Ac2.
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PMID:[The nature of the influenza C virus receptor and the specificity of the receptor-destroying enzyme]. 244 6

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

T cells from enlarged lymph nodes of MRL/MpJ-lpr/lpr (lpr) mice were found to express more binding sites for strongly hemagglutinating Phaseolus vulgaris agglutinin (PHA-E4) and fewer binding sites for Ricinus communis aglutinin (RCA) than those from normal MRL/MpJ-+/+ (+/+) mouse lymph node. We found that high-molecular-weight (180K-220K) glycoproteins on lpr T cells were strongly stained with these lectins on Western-blotting. These glycoproteins were found to belong to the CD45 family, by absorption with monoclonal anti-CD45 antibody. We also found that the other glycoproteins (105K and 120K glycoproteins on lpr T cells and a 105K glycoprotein on +/+ T cells) were strongly stained with the lectins which preferentially bind to mucin-type (O-linked) sugar chains on the cell surface. These glycoproteins were found to be leukosialins, by absorption with anti-leukosialin serum. From the results of the lectin-binding to these glycoproteins after sialidase treatment, CD45 antigens and leukosialin molecules on lpr T cells were found to have many more terminal alpha 2,3-linked sialic acids than those on +/+ T cells, and this fact explains why lpr T cells have more binding sites for PHA-E4 but fewer binding sites for RCA.
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PMID:Alpha 2,3-linked sialic acids are more abundant in CD45 antigens and leukosialins of abnormal T cells of lpr mice than in those of normal T cells. 253 27

Surgically obtained rectosigmoid mucosa ("transitional" mucosa, TM) adjacent to eight primary carcinomas was compared with diseased mucosa (DM) from eight patients without primary carcinoma and mucosa from two normal control subjects by mucin histochemical and morphologic techniques. No differences were found between TM and DM that might have suggested premalignant changes unique to TM. An excess of sialidase-susceptible sialomucins was found in both TM and DM, as was loss of the sulfomucin-sialomucin gradient usually found between normal crypts and surface cells. Increased sialic acid in TM and DM may represent a nonspecific response to injury or inflammation and has been found in other epithelia under similar circumstances. Sialidase also induced substantial reduction of periodic acid-Schiff (PAS) staining, probably due to loss of sialic acid since no other sugars were released during sialidase digestion, as determined by thin-layer chromatography analysis of post-digestion supernatants. Carcinomas generally showed more staining with PAS than with basic dyes; PAS staining was minimally reduced by diastase and sialidase but markedly reduced by phenylhydrazine interposition, suggesting that some type of neutral glycoprotein was responsible. Finally, it was found that overreliance on the high-iron diamine-Alcian blue technique as a single procedure is unwise; this procedure should be accompanied by the use of singly applied dyes, especially high-iron diamine, together with other enzymatic and staining procedures.
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PMID:Histochemical and morphologic studies of mucosa bordering rectosigmoid carcinomas: comparisons with normal, diseased, and malignant colonic epithelium. 257 14

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

The cell-bound sialidase of Actinomyces viscosus DSM 43798 was solubilized by mechanical cell disruption and lysozyme treatment. The enzyme was enriched 30,000-fold by cation-exchange chromatography, gel-filtration, and FPLC ion-exchange chromatography, thus obtaining 10 micrograms sialidase protein from 26 g wet cells with a specific activity of 680 U/mg protein. Since sialidase activity was also found in the culture medium, this enzyme was isolated as well, requiring the additional application of FPLC gel-filtration. Both sialidase preparations were apparently homogenous on SDS-PAGE and have similar properties. The substrate specificity of the A. viscosus sialidase was tested with 16 sialoglycoconjugates: The enzyme showed a higher activity with serum glycoproteins than with gangliosides, mucins or sialyllactoses. 4-O-Acetylated N-acetylneuraminic acid was not cleaved from equine submandibular gland mucins or serum glycoproteins in contrast to N-acetyl- and N-glycoloylneuraminic acid. 9-O-Acetyl-N-acetylneuraminic acid was released from bovine submandibular gland mucin, as confirmed by TLC. The sialidase hydrolyses alpha(2----6)-linkages more rapidly than alpha(2----8)- and alpha(2----3)-bonds. Cations, except Hg2+, or chelating agents have no influence on enzyme activity. The sialidase has a relatively high molecular mass of 150 kDa, but consists of only one unit. The enzyme is labile towards freezing and thawing, but can be stored at 4 degrees C in 0.1 M acetate buffer, pH 5.
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PMID:Properties of sialidase isolated from Actinomyces viscosus DSM 43798. 274 53


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