Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study is to investigate the mechanism on enhanced hemagglutination caused by neuraminidase from Bacteroides in an aspect of zeta-potential levels on erythrocytes and inhibitors on hemagglutination activity. The neuraminidase from the culture medium of Bacteroides loescheii ATCC 15930 was purified by ultrafiltration followed by DEAE-Sephacel anion exchange chromatography, fast protein, polypeptide, polynucleotide, liquid chromatography using Mono P column and finally high performance liquid chromatography using Shim-pack Diol-300 column. The purified enzyme appeared to be homogeneous by analytical polyacrylamide gel electrophoresis. The molecular weight was measured to be approximately 87,000 and the optimal pH was at 4.8. The isoelectric point was at 5.1. The enzyme showed relatively high specificity toward the linkage of NANA alpha (2----3) oligosaccharides and glycoproteins, and less toward the linkage of NANA alpha (2----6), and/or NANA alpha (2----8) oligosaccharides. When the human erythrocytes were treated by the purified enzyme, hemagglutination activities of some strains of Bacteroides gingivalis, Bacteroides denticola and Bacteroides intermedius were enhanced. Hemagglutination inhibition experiments using B. gingivalis 381 showed that the activity of hemagglutination was strongly inhibited by the arginine-containing peptides especially salmine derived from salmon, although the activity was unaffected by the sugars, amino acids and divalent cations such as Ca2+, Mn2+ and Mg2+. The zeta-potential level on asialo-erythrocytes treated by purified enzyme was considerably decreased compared to that of sialo-erythrocytes. It seems likely that the mechanism on hemagglutination by the B. gingivalis 381 may be involved in electrochemical affinity between the erythrocytes and bacterial cells with the reduction of zeta-potential, and in arginine-containing peptides as receptors of ligand-binding on erythrocytes.
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PMID:[Purification and some properties of neuraminidase from the culture medium of Bacteroides loescheii ATCC 15930]. 248 23

Lysosomal neuraminidase from human placenta has been obtained in its active form by association of an inactive neuraminidase polypeptide with beta-galactosidase and the protective protein. Using a specific antiserum, we have now identified a 66-kDa protein as the inactive neuraminidase polypeptide. It is specifically recognized on immunoblots only in its nonreduced state, and it coprecipitates with neuraminidase activity. The 66-kDa polypeptide is substantially glycosylated (38-kDa protein core with 7-14 N-linked oligosaccharide chains), a feature characteristic of lysosomal integral membrane proteins. Specific removal of the 66-kDa neuraminidase polypeptide from glycoprotein preparations prevents the generation of neuraminidase activity. Removal of beta-galactosidase or destruction of the protective protein also hinders the formation of active neuraminidase. Reconstitution of neuraminidase activity is observed after mixing glycoprotein preparations, depleted in different components of the beta-galactosidase-neuraminidase-protective protein complex, indicating that all three components of the complex are required for neuraminidase activity. Association of the neuraminidase polypeptide and the protective protein generates unstable neuraminidase activity, whereas association with beta-galactosidase is required for stability.
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PMID:Identification and in vitro reconstitution of lysosomal neuraminidase from human placenta. 249 18

To characterize the molecular polymorphism of the DP alpha and DP beta gene products, the HLA-DP molecules expressed by more than 200 cell lines were individually immunoprecipitated by using the mAb B7/21 and their neuraminidase-treated DP alpha and DP beta chains analyzed in IEF gels. These cell lines, most of them from members of 32 families, allowed the definition, by segregation analysis, of the IEF patterns of the DP polypeptide chains encoded by 129 distinct haplotypes. Both DP alpha and DP beta chains display polymorphic IEF-banding patterns. Two DP alpha (A and B) and seven DP beta (A, B, C, D, E, F, and G) IEF variants were characterized. The DP alpha B variant was found in linkage disequilibrium with both DP beta B and DP beta D. Linkage disequilibrium was also encountered with alleles at the DR and DQ loci. Finally, the correlations between the IEF DP alpha and DP beta variants and the primed lymphocyte test-defined HLA-DP specificities were determined by using a panel of 24 primed lymphocyte test-typed cell lines.
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PMID:Molecular characterization by high resolution isoelectric focusing of the products encoded by the class II region loci of the MHC in humans. II. DP alpha and DP beta gene variants. 249 30

Human prostatic acid phosphatase is known to display considerable charge heterogeneity upon isoelectric focusing. The structural basis of this heterogeneity is not known, although it has been widely attributed to variations in the nature of the carbohydrate chains or to substituents on the carbohydrate chains of the glycoprotein. In this study, the role of the carbohydrate chains in the charge heterogeneity of the protein was examined. First, sialic acid residues were removed by treatment of the acid phosphatase with neuraminidase. The desialo enzyme was fractionated and purified by L-tartramic acid affinity chromatography. Then, after the protein oligosaccharide linkages were made accessible by the presence of NP-40 or by denaturing the protein, the protein was completely deglycosylated by endo-beta-N-acetylglucosaminidase F at pH 4.5 and 9.3. Two discrete intermediates were clearly resolved by SDS gel electrophoresis during the deglycosylation of the denatured protein at pH 9.3, indicating the existence of three sites of glycosylation on the protein. Peptide mixtures were obtained by digestion of carboxymethylated and citraconylated derivatives of the enzyme with trypsin and the glycopeptides were isolated. The amino acid compositions of the glycopeptides were consistent with the interpretation that there are a minimum of two sites of glycosylation on each peptide subunit of the enzyme. Isoelectric focusing experiments on the native, desialo, and denatured, deglycoso acid phosphatase showed that the heterogeneity of the protein is not eliminated either by desialylation or by deglycosylation. Thus, the electrophoretic heterogeneity of human prostatic acid phosphatase does not lie primarily in the oligosaccharide part of the glycoprotein or in altered conformational states of the protein, but in structural variations of the polypeptide itself. The heterogeneity may be due to variations at the C-terminus, partial deamidation, phosphorylation, sulfation or other posttranslational modifications of the protein chain.
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PMID:Carbohydrate removal fails to eliminate the heterogeneity of human prostatic acid phosphatase. 250 33

The structural characteristics and glycosylation properties of the lactogenic receptor were examined in 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS)-solubilized plasma membranes from female mouse liver. The specific binding of the radioiodinated human growth hormone [( 125I]hGH) was displaced with an equivalent potency by both hGH and prolactin. After a mild neuraminidase treatment, this binding was increased by 40%, as a result of an increase in receptor affinity. Affinity chromatography on immobilized lectins revealed that the [125I]hGH-receptor complexes were specifically retained and eluted from ricin lectin-agarose, concanavalin A and lentil lectin, indicating the presence of N-linked glycans. Covalent cross-linking of solubilized [125I]hGH-receptor complexes with disuccinimidyl suberate, followed by analysis by sodium dodecyl sulfate-gel electrophoresis (SDS-PAGE) under reducing conditions, and autoradiography resulted in the appearance of two bands with apparent Mr approximately 62,000 and approximately 100,000. The labelling of these bands was prevented by unlabelled hGH or ovine prolactin (oPrl) but not by bovine growth hormone (bGH). Neuraminidase treatment of the two receptor forms resulted in increased electrophoretic mobility which was inhibited by simultaneous addition of sialyl-lactose, a neuraminidase substrate. The both cross-linked forms were unaffected by endoglycosidase H, while endoglycosidase F decreased the molecular weight of each of the forms by about 8000 Da, yielding bands at Mr approximately 54,000 and approximately 92,000. In conclusion, taking into account that hGH is a Mr 22,000 polypeptide, the two forms of the receptor correspond to glycoproteins of Mr approximately 40,000 and approximately 78,000, respectively. They contain polypeptide backbones of Mr approximately 32,000 and approximately 70,000, and complex N-linked oligosaccharide chains with terminal sialic acid residues which could be involved in receptor binding affinity.
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PMID:Glycosylation characteristics of the mouse liver lactogenic receptor. 250 88

Isoelectric focusing and immunoblotting reveals considerable biochemical and genetic variation in the C1R subcomponent of the first complement component. The nature of the intraindividual biochemical variation can be explained by differences in sialic acid content because after digestion with neuraminidase the terminal sialic acids are removed to yield a single major band corresponding to the C1R polypeptide. Plasma samples from a large number of different ethnic groups, consisting of U.S. whites, U.S. blacks, Nigerian blacks, and Inuit, Aleut, and Amerindian populations from the Western Hemisphere have revealed genetically determined charge variation with heterozygous phenotypes consisting of two major asialo bands, indicating that the underlying variation is not due to variation in sialic acid content. Two previously reported common alleles, C1R*1 and CIR*2, have been observed in all studied populations, the notable exception being the Dogrib Indian population, which is devoid of the C1R*2 allele. Several new alleles--designated C1R*3, C1R*4, C1R*5, C1R*6, and C1R*7-have been observed, with variable frequencies ranging from the occurrence in a single individual and related family members to the polymorphic occurrence of certain alleles in several populations. Of these new alleles, the C1R*5 is of considerable interest in population and anthropological genetics studies. The C1R*5 allele is widely distributed, at a frequency of .03 to .17, in all of the North American aboriginal populations screened. This allele is not present in U.S. whites but is present at a polymorphic frequency in U.S. and Nigerian blacks.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Genetic studies of low-abundance human plasma proteins. XIII. Population genetics of C1R complement subcomponent and description of new variants. 253 73

Chemical affinity cross-linking studies have identified brain and pituitary CRF receptors with similar pharmacological characteristics but different mol wts (anterior pituitary, 75,000; brain, 58,000). In order to determine whether the heterogeneous nature of CRF receptors was inherent in the protein, we examined the glycoprotein nature of both types of CRF receptors using lectin affinity chromatography and treatments with exo- and endoglycosidases. CRF receptors in both the cerebral cortex and anterior pituitary adsorbed to and specifically eluted from Concanavalin-A- and wheat germ agglutinin-immobilized lectin affinity columns, indicating that both forms of the receptor are glycoproteins containing complex and high-mannose carbohydrate moieties. Cerebral cortical CRF receptors were sensitive to both neuraminidase and alpha-mannosidase treatment while pituitary CRF receptors were only affected by neuraminidase treatment, suggesting that CRF receptors in brain and pituitary differed slightly in the nature of their glycosylation units. After treatment of cerebral cortical or anterior pituitary CRF receptors with the endoglycosidase, N-glycanase, the mol wts were markedly decreased; the mol wt of the anterior pituitary CRF receptor was decreased from 75,000 to approximately 40,000-45,000 while in a corresponding manner, the cortical receptor was decreased from 58,000 to approximately 40,000-45,000. Limited proteolysis after deglycosylation with N-glycanase using the proteinases Staphylococcus aureus V8 (S. aureus V8) or papain, generated virtually identical peptide fragments from anterior pituitary- or cerebral cortex- labeled CRF receptor proteins. In summary, these data support the hypothesis that the ligand binding subunit of the CRF receptor in both brain and pituitary resides on a polypeptide of 40,000-45,000 and appears to be identical in both tissues. Differences observed in the mobility of the two proteins were found to be due to differences in the posttranslational modification of the proteins in the two tissues.
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PMID:Heterogeneity between brain and pituitary corticotropin-releasing factor receptors is due to differential glycosylation. 255 31

This work describes the purification of FAP, a feto-acinar pancreatic protein associated with the ontogenesis, differentiation, and transformation of the human exocrine pancreas. The protein was purified to homogeneity from pancreatic juices of patients with pancreatic pathology by a two-step chromatographic procedure which consisted of size exclusion on Sephacryl S-200 and affinity on heparin-Sepharose. The final preparation gave a single band at Mr 110,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after Coomassie stain or autoradiography of the 125I-labeled protein. Immunodetection with the murine monoclonal antibody mAb J28 in nitrocellulose replicas demonstrated a main Mr 110,000 component and trace components in the Mr 100,000-80,000 range. The immunopattern was identical to that in the original crude pancreatic secretion, therefore showing that the molecular characteristics of the protein, i.e. molecular mass, microheterogeneity, and immunoreactivity, were not altered along the purification procedure. FAP was identified as an acidic protein (isoelectric point 4.2-4.8) consisting of a single polypeptide chain having no free SH residues. Analysis of the amino acid composition showed a high proline content. Twenty-two residues of the N-terminal sequence were determined. No significant homology between this peptide and other proteins was found following a search of the NBRF-18 data bank. Sugar analysis showed the presence of mannose which is consistent with N-linked carbohydrate chains and an unusual high ratio in N-acetylgalactosamine residues suggesting the presence of many O-linked carbohydrate chains. Sequential deglycosylation with neuraminidase, hexosaminidase, and O-glycanase yield a single Mr 58,000 peptide showing that, relative to a molecular mass of 110,000, the carbohydrate moiety of FAP accounts for at least 47% of its apparent Mr by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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PMID:Purification and molecular characterization of FAP, a feto-acinar protein associated with the differentiation of human pancreas. 260 91

Crystals suitable for X-ray diffraction studies at moderate resolution have been grown from two forms of human chorionic gonadotropin (hCG): HF-treated hCG and neuraminidase-treated hCG. The enzymatically desialylated form of hCG produced crystals that diffract to 2.8 A as compared to the HF-treated hCG crystals that diffract to 3.0 A. Although it was assumed that the high and heterogeneous carbohydrate content of the glycoprotein hormones inhibited their crystallization, this report suggests that it is the negatively charged surface sugars and neither the total carbohydrate content nor its heterogeneity which interferes with crystal formation. Chemical deglycosylation resulted in significantly increased protein degradation during crystal growth. Such peptide bond cleavages were observed to a much lesser extent in the crystals grown from neuraminidase-digested hCG. Sequence analysis of the HF-treated hCG crystals suggested that up to 45% of the molecules within the crystal had an acid-labile peptide bond cleaved. In contrast, the neuraminidase-treated hCG exhibited less than 9% of this type of cleavage. The increase in heterogeneity of the polypeptide chains within both crystals over that existent in the starting proteins was apparently due to changes occurring during crystal growth. The manner in which hCG was treated prior to crystallization was found to be a very important factor in the extent of peptide bond cleavages occurring during crystal growth. HF treatment of glycoproteins may render glycoproteins more susceptible to peptide bond cleavages during crystal growth.
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PMID:Crystallization and characterization of human chorionic gonadotropin in chemically deglycosylated and enzymatically desialylated states. 261 Dec 25

The effect of enzymatic deglycosylation of human complement component C9 on its hemolytic activity was investigated. Treatment of native C9 (Mr 71,000) with glyocpeptidase F (PNGase F) results in a stepwise decrease of the mol. wt. The formation of an Mr 67,000 peptide which is further converted to Mr 63,000 suggests that there are two N-linked carbohydrate chains per C9 polypeptide. Removal of approximately 88% of the N-linked oligosaccharides results in 80% reduction of the hemolytic activity (CH50). The completely N-deglycosylated Mr 63,000 peptide contains a remaining amount of 25% of the total carbohydrates of native C9. These glycans are assumed to be O-linked and predominantly attached to the C9a part of C9. The electrophoretic mobility of C9 is not affected by endoglycosidase F or H treatments revealing that the two N-linked glycans are of the tri- or tetra-antennary complex type. Cleavage of terminal sialic acids from native C9 by neuraminidase results in an Mr 67,000 product with nearly unaltered hemolytic activity. In contrast to other glycoproteins in which deglycosylation remained without major effects on their functional activity, our findings suggest that the N-linked carbohydrates are required for full expression of hemolytic activity of C9.
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PMID:N-deglycosylation of human complement component C9 reduces its hemolytic activity. 263 47


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