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)

Optimal assay conditions are described for plasma alpha-galactosidase, beta-glactosidase, beta-glucuronidase, alpha-mannosidase, alpha-glucosidase, N-acetyl-beta-glucosaminidase, alpha-fucosidase, N-acetyl-alpha-glucosaminidase, acid phosphatase and arylsulphatase A. The levels of these activities in normal adults and children, and the stabilities of the activities on storage at -20 degrees C or 4 degrees C, are reported. The levels of these enzymic activities in plasma from patients with Fabry, Pompe, Sanfilippo A, Sanfilippo B, Tay Sachs and Hunter diseases, GM1-gangliosidosis and metachromatic leucodystrophy are described, and the possibility of using plasma hydrolase activities in the diagnosis of these conditions is discussed.
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PMID:Plasma acid hydrolases in normal adults and children, and in patients with some lysosomal storage diseases. 3 Dec 50

Intestinal brush borders from Wistar rats contained a total of 20-30-times more binding sites for Escherichia coli heat-labile enterotoxin (LT-1) than for cholera toxin (CT). The results suggest that LT-1 binds to sites in addition to ganglioside GM1, the binding site for CT. Brush border proteins were separated by SDS-PAGE, blotted to nitrocellulose and the filters incubated with 125I-labeled toxins. [125I]LT-1 was shown to bind to a series of brush border galactoproteins ranging in size from 130-140 kDa. Binding was inhibited by unlabeled LT-1 (but not CT), and by ricin and free galactose. A number of brush border enzymes are large glycoproteins which can be solubilised by papain. The papain-solubilised sucrase-isomaltase complex was purified by affinity chromatography and shown to bind LT-1, as did the proteins in fractions enriched in maltase activity. However, such brush border galactoproteins do not account for all of the additional LT-1 binding sites. Thus, brush borders prepared from 1-15-day-old rabbits contained many more binding sites for LT-1 than CT despite the absence of any sucrase-isomaltase activity, and no [125I]LT-1 binding proteins could be detected by blotting. There was a marked variation in the number of LT-1 binding sites in different strains of rat, and between different species.
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PMID:Characterisation of the binding sites for Escherichia coli heat-labile toxin type I in intestinal brush borders. 193 71

The generation of enzymes located in lysosomes, in cytosol or in endoplasmatic reticulum/Golgi complex is studied in heterokaryons in which chick erythrocyte nuclei are reactivated. The lysosomal enzymes, alpha-glucosidase (alpha-glu) and beta-galactosidase (beta-gal), are synthesized in heterokaryons obtained after fusion of chick erythrocytes with human fibroblasts of patients with Pompe's disease (alpha-glu-deficient) and GM1-gangliosidosis (beta-gal-deficient), respectively. The enzymes appear to be of chick origin and their activities can be detected at first around 4 days after fusion, i.e., at a time when the nucleoli in the erythrocyte nuclei have been reactivated. Maximal activities are reached around 15 days after fusion. No generation of the lysosomal enzyme beta-hexosaminidase is detected in the heterokaryons up to 23 days after fusion of chick erythrocyte with either beta-hexosaminidase A- and B-deficient fibroblasts (Sandhoff's disease) or beta-hexosaminidase A-deficient fibroblasts (Tay-Sachs disease). Similarly no expression of the cytosol enzyme glucose-6-phosphate dehydrogenase (G6PD) is fond up to 30 days after fusion, when chick erythrocytes are fused with fibroblasts from two different G6PD-deficient cell strains (residual activities of 4 and 20% respectively). Indirectly we examined N-acetyl-glucosamine-1-phosphate transferase activity, an enzyme located in the endoplasmic reticulum/Golgi region. This enzyme is needed for the phosphorylation of the lysosomal hydrolases and absence of its activity is the cause of the multiple lysosomal enzyme deficiencies in patients with I-cell disease. The retention of both, chick and human beta-galactosidase in the experiments in which I-cell fibroblasts were fused with chick erythrocytes indicates a reactivation of the gene coding for this phosphorylating enzyme. It also implies that this step in the processing of human lysosomal enzymes is not species-specific.
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PMID:Expression of lysosomal enzymes in human mutant fibroblast-chick erythrocyte heterokaryons. 629 65

Human colon adenocarcinoma cells (HT29-ATCC) and the clone HT29-5F7 were cultured under conditions that differentiate cells to a polarized intestinal phenotype. Differentiated cells showed the presence of junctional complexes and intercellular lumina bordered by microvilli. Intestinal brush border hydrolase activities (sucrase, aminopeptidase N, lactase and maltase) were detected mainly in differentiated HT29-ATCC cells compared with the differentiated clone, HT29-5F7. The presence of non-GM1 receptors of Escherichia coli heat-labile enterotoxin (LT-I) on both types of differentiated HT29 cells was indicated by the inability of cholera toxin B subunit to block LT-I binding to the cells. Binding of LT-I to cells, when GM1 was blocked by the cholera toxin B subunit, was characterized by an increased number of LT-I receptors with respect to undifferentiated control cells. Moreover, both types of differentiated cells accumulated higher amounts of cyclic AMP in response to LT-I than undifferentiated cells. Helix pomatia lectin inhibited the binding of LT-I to cells and the subsequent production of cyclic AMP. LT-I recognized blood group A-active glycosphingolipids as functional receptors in both HT29 cell lines and the active pro-sucrase form of the glycoprotein carrying A-blood group activity present in HT29-ATCC cells. These results strongly suggest that LT-I can elicit an enhanced functional response using blood group A-active glycoconjugates as additional receptors on polarized intestinal epithelial cells.
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PMID:Functional interaction of Escherichia coli heat-labile enterotoxin with blood group A-active glycoconjugates from differentiated HT29 cells. 1688 90