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:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of the lectins concanavalin A (Con A) and wheat germ agglutinin (WGA) to the luminal surface of lung alveolar epithelial cells was compared in normal rats and rats with streptozotocin-induced diabetes and their offspring. Lung tissue was lavaged, then fixed in situ with 3% glutaraldehyde. Buffer-rinsed slices of lung were incubated in Con A, WGA, or various control media. Lectin binding sites were visualized by the use of the peroxidase method. Normal neonates and those that were the results of diabetic pregnancies showed a hexose-specific Con A and WGA binding pattern qualitatively similar to that of normal and diabetic adults, respectively. In the normal animals, Con A binding sites were masked by sialic acid residues and were removable with alpha-mannosidase after neuraminidase treatment. In the diabetic adults and their offspring, one the other hand, Con A binding sites were readily accessible and were totally removed only by sequential treatment with alpha-mannosidase and alpha-glucosidase. WGA binding was essentially eliminated with neuraminidase in all animals except in the neonates from diabetic pregnancies, where N-acetyl-glucosaminidase was also required. The effects of maternal diabetes were reversible and occurred about Day 7 postpartum in the neonate. The effects were also reversible following insulin replacement in the diabetic adult.
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PMID:Diabetic pregnancy. Changes in lectin binding to the surface of rat lung alveolar epithelial cells. 668 9

The activities of various glycosidases in homogenates of the small intestinal mucosa of two adult and 18 suckling tammar wallabies (M. eugenii) aged from 6 to 50 weeks were investigated. Lactase (beta-D-galactosidase), beta-N-acetylglucosaminidase, alpha-L-fucosidase and neuraminidase activities were high during the first 34 weeks post partum and then declined to very low levels. Maltase, isomaltase, sucrase and trehalase activities were very low or absent during the first 34 weeks, and then increased. The lactase activity was unusual in being greater in the distal than the middle or proximal thirds of the intestine, and in its low pH optimum (pH 4.6), inhibition by p-chloromercuribenzene sulfonate but not by Tris, and lack of cellobiase activity. These properties are those of a lysosomal acid beta-galactosidase rather than of a brush border neutral lactase. The maltase activity had the characteristics of a lysosomal acid alpha-glucosidase early in lactation and of a brush border neutral maltase in adult animals. The significance of these findings is discussed in relation to changes in dietary carbohydrates during weaning and to the mode of digestion of milk carbohydrates by the pouch young.
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PMID:Intestinal lactase (beta-galactosidase) and other glycosidase activities in suckling and adult tammar wallabies (Macropus eugenii). 678 21

The low activity of liver neuraminidase that is characteristic of mouse strain SM/J is inherited as a single gene on chromosome 17, near the major histocompatibility complex. This gene, neuraminidase-1 (Neu-1), is represented by the low activity allele Neu-1s in SM/J and the high activity allele Neu-1b in C57BL/6J and most other strains. Previously described variations in the posttranslational processing of acid phosphatase, alpha-mannosidase, arylsulfatase-B, and alpha-glucosidase are attributed to pleiotropic effects of this gene.
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PMID:Gene for neuraminidase activity on mouse chromosome 17 near h-2: pleiotropic effects on multiple hydrolases. 720 20

The activity of particulate neuraminidase (sialidase, EC 3.2.1.18) in wild-type mice and the neurological mutant Staggerer was studied during development. Peak activity of this enzyme was observed at postnatal day 3 (P3) in three tissues of normal mice: cerebellum, cerebrum, and liver. In Staggerer, however, neuraminidase peak activity was observed at P27 in the cerebellum, whereas the activity was close to normal in Staggerer cerebrum and liver. Activities of the other glycosidases in Staggerer (alpha-glucosidase (pH 3.7), alpha-glucosidase (pH 6.0), N-acetyl-beta-hexosaminidase, beta-glucosidase, and beta-galactosidase) did not show significant variation compared with wild-type at P27 in any of the three tissues. This indicates that the late activity peak of particulate neuraminidase activity in the Staggerer cerebellum is neuraminidase-specific and not due to a general increase of lysosomal enzymes.
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PMID:Changes in particulate neuraminidase activity during normal and staggerer mutant mouse development. 726 67

Nectrisine, discovered as an immunomodulator, was found to inhibit alpha-glucosidase, alpha- and beta-mannosidases, beta-glucosidase and beta-N-acetylglucosaminidase, in that order of inhibition strength. Beta-Galactosidase, alpha-fucosidase, and neuraminidase were insensitive to this antibiotic. Also sensitive was the trimming glucosidase I which participates in the first step of modifying N-glycosidic oligosaccharide. Nectrisine demonstrated an inhibitory effect at the cellular level as strong as expected based on its action at enzyme levels; castanospermine and 1-deoxynojirimycin did not. Nectrisine and castanospermine suppressed syncytium formation and hemolytic activity in Newcastle disease virus (NDV)-infected BHK cells, without blocking the synthesis and cell-surface expression of HANA glycoprotein of NDV.
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PMID:Nectrisine is a potent inhibitor of alpha-glucosidases, demonstrating activities similarly at enzyme and cellular levels. 864 27

Escherichia coli heat-stable enterotoxin b (STb) causes severe diarrhoea in weaning piglets. STb most probably has to bind to intestinal epithelial cells in order to achieve its effect. Using biotinylated biologically active STb, we developed a semi-quantitative binding assay using indirect fluorescence microscopy. We demonstrated the attachment of the biotinylated toxin to microvilli of the pig jejunum. However, binding was abolished when biotinylated STb was either boiled or treated with 2-mercaptoethanol, treatments known to abolish biological activity. Different characteristics of STb attachment to the pig small intestine were determined. The reaction was rapid and reached maximum intensity after approximately 10 min. The binding was pH dependent showing an optimum at pH 5.8. Incubation at either 4 degrees C, 25 degrees C or 37 degrees C did not affect the binding. No competition was observed with non-biotinylated STb. However, preincubation of biotinylated STb with streptavidin conjugated to horseradish peroxidase completely abolished the binding. Pig tissues other than jejunum demonstrated binding towards STb including duodenum, ileum, caecum, colon, liver, lung, spleen and kidney. The molecule involved was then partially characterized. Metaperiodate treatment of the jejunum sections abrogated binding but protease treatment had no effect. Enzymatic treatments of jejunal sections demonstrated that N- and O-glycosidases, and several exoglycosidases did not affect binding, whereas reduced binding was observed with ceramide glycanase and alpha-glucosidase, and was completely abolished following neuraminidase treatment. Overall, our results suggest that in vitro STb binding was rapid, pH dependent, temperature independent, not restricted to jejunum and involves a molecule that seems to be composed of a ceramide moiety, terminal neuraminic acid and/or alpha-linked terminal glucose residue(s).
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PMID:Binding characteristics of Escherichia coli enterotoxin b (STb) to the pig jejunum and partial characterization of the molecule involved. 960 Aug 60

Mannose-binding lectin (MBL), a C-type lectin component of the human innate immune system, binds to the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1). The objective of this study was to assess the effects of inhibitors of endoplasmic reticulum glucosidases and Golgi mannosidase as well as neuraminidase (NA) on the interaction between HIV and MBL. Production of HIV in the presence of the mannosidase I inhibitor deoxymannojirimycin (dMM) significantly enhanced binding of HIV to MBL and increased MBL neutralization of an M-tropic HIV primary isolate. In contrast, culturing HIV in the presence of alpha-glucosidase I and II inhibitors castanospermine and deoxynojirimycin only slightly affected virus binding and neutralization by MBL. Removal of sialic acid from HIV by NA also significantly enhanced virus binding and neutralization by MBL. Treatment of virus grown in the presence of dMM with endoglycosidase F1 substantially reduced binding to MBL, indicating that dMM increased MBL binding by increasing high-mannose carbohydrates on the virus. In contrast, endoglycosidase F1 did not decrease the MBL interaction with NA-treated virus, suggesting that NA exposed novel MBL binding sites. Treatment with dMM increased the immunocapture of HIV by monoclonal antibodies 2F5 and 2G12, indicating that altering the glycosylation of viral glycoproteins increases the accessibility or reactivity of some epitopes. This study shows that specific alterations of the N-linked carbohydrates on HIV gp120/gp41 can enhance MBL-mediated neutralization of virus by strengthening the interaction of HIV-1 with MBL.
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PMID:Glycosylation inhibitors and neuraminidase enhance human immunodeficiency virus type 1 binding and neutralization by mannose-binding lectin. 1256 May 67

Coproantigen ELISA based tests for diagnosis of canine echinococcosis provide high specificity and sensitivity. However, the antigenic molecules present in faeces from infected dogs have not yet been characterised. While initial attempts to determine the molecular weights of Echinococcus granulosus coproantigens by SDS-PAGE and Western blotting with coproantigen reactive capture antibodies were equivocal, they suggested presence of a significant carbohydrate component. Periodate treatment of coproantigen positive faecal supernatants resulted in a significant reduction (53%) in ELISA activity, suggesting that carbohydrates are involved in the antigenic structure of E. granulosus coproantigens. Protease treatment of antigenic molecules resulted in an 11% reduction in absorbance in ELISA, indicating that protein components were also present which affected by enzyme activity. Lectin-binding ELISA assays indicated strong affinity of E. granulosus coproantigens to concanavalin agglutinin and Lens culinaris agglutinin, and moderate binding to wheat-germ agglutinin and peanut agglutinin. No binding was detectable to Ulex europaensis agglutinin-I, Bandeiraea simplicifolia or Dolichos biflorus agglutinin. These data indicate that E. granulosus coproantigens from infected dog faeces possibly contained alpha-D-mannose and/or alpha-D-glucose, beta-galactose and N-acetyl-beta-glucosamine residues. To verify the role of carbohydrate moieties in coproantigens, faecal samples were treated with exoglycosidase and tested in the coproantigen ELISA. Treatment with beta-galactosidase or N-acetyl-beta-glucosamine reduced ELISA activity by 44 and 30%, respectively. Incubation with a panel of other specific exoglycosidases including alpha-galactosidase as well as alpha-L-fucosidase, alpha-mannosidase, beta-mannosidase, alpha-glucosidase, beta-glucosidase, beta- fructosidase, or neuraminidase, did not alter coproantigen detection in ELISA. The results indicate that coproantigens present in faeces from E. granulosus naturally infected dogs were highly glycosylated and contain beta- galactose and N-acetyl-beta-glucosamine. The putative relationship of antigenic molecules with the tapeworm glycocalyx is discussed.
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PMID:Partial characterisation of carbohydrate-rich Echinococcus granulosus coproantigens. 1457 18

Angiotensin I-converting enzyme (ACE, peptidyl dipeptidase, EC 3.4.15.2) is a key enzyme in cardiovascular pathophysiology. A wide spectrum of monoclonal antibodies to different epitopes on the N and C domains of human ACE has been used to study different aspects of ACE biology. In this study we characterized the monoclonal antibody (mAb) 5F1, developed against the N domain of human ACE, which recognizes both the catalytically active and the denatured forms of ACE. The epitope for mAb 5F1 was defined using species cross-reactivity, synthetic peptide (PepScan technology) and phage display library screening, Western blotting, site-directed mutagenesis, and protein modeling. The epitope for mAb 5F1 shows no overlap with the epitopes of seven other mAbs to the N domain described previously and is localized on the other side of the N domain globule. The binding of mAb 5F1 to ACE is carbohydrate-dependent and increased significantly as a result of altered glycosylation after treatment with alpha-glucosidase-1 inhibitor, N-butyldeoxynojirimycin (NB-DNJ), or neuraminidase. Out of 17 species tested, mAb 5F1 showed strict primate ACE specificity. In addition, mAb 5F1 recognized human ACE in Western blots and on paraffin-embedded sections. The sequential part of the epitope for mAb 5F1 is created by the N-terminal part of the N domain, between residues 1 and 141. A conformational region of the epitope was also identified, including the residues around the glycan attached to Asn117, which explains the sensitivity to changes in glycosylation state, and another stretch localized around the motif 454TPPSRYN460. Site-directed mutagensis and inhibition assays revealed that mAb 5F1 inhibits ACE activity at high concentrations due to binding of residues on both sides of the active site cleft, thus supporting a hinge-bending mechanism for substrate binding of ACE.
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PMID:Fine epitope mapping of monoclonal antibody 5F1 reveals anticatalytic activity toward the N domain of human angiotensin-converting enzyme. 1763 Jul 79


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