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 longitudinal distribution of different brush border enzymes along the human small intestine was studied by crossed immunoelectrophoresis. The results are based on biopsies taken every 50 cm in three intestines obtained at autopsy and on peroral or peroperative biopsies from the ligament of Treitz, proximal jejunum and distal ileum from 11 patients undergoing jejunoileal bypass operation for obesity. Lactase-phlorizin hydrolase (EC 3.2.1.23-62) and sucrase-isomaltase(EC 3.2.1.48-10) had their highest level in jejunum with decreasing activity towards the proximal and distal ends of the intestine, while maltase (EC 3.2.1.20) increased along the intestine and reached its highest activity in the distal ileum. A carboxypeptidase (EC 3.4.12.X) is demonstrated as an enzymatic entity of the human intestine. This enzyme had a rather flat distribution curve while microvillus aminopeptidase (EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.X) and aspartate aminopeptidase (EC 3.4.11.7) all increased along the length axis and reached maximum values in distal ileum.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins--the longitudinal distribution of peptidases and disaccharidases. 611 68

1. The disaccharidases, cellobiase, isomaltase, lactase, maltase, sucrase and trehalase were investigated for presence in the camel (Camelus dromedarius) intestine and pancreas. All, except sucrase, were present. 2. Their levels of activities were measured at different positions of the small and large intestines and the location of maximum level of activity for each enzymes along the intestinal tract was established. 3. High levels of activities were determined in the contents of the intestinal lumen and, therefore, it is absorbed into the cells of the epithelial villi and hydrolyzed there. 4. The possibility of carbohydrate digestion in camel intestine is discussed.
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PMID:The level and distribution of disaccharidases in the camel (Camelus dromedarius) intestine. 612 46

A largely unrecognized immunoadsorbent desorption technique, hypotonic elution, has been successfully used in the immunoadsorbent purification of the microvillar enzymes aminopeptidase N (EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.5), sucrase-isomaltase (EC 3.2.1.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62) and maltase-glucoamylase (EC 3.2.1.20). This elution method proved capable of achieving an acceptable yield (30-70%) while at the same time preserving the purified enzymes in an enzymically active state. It hereby offers a solution to the problem in immunoadsorbent chromatography of finding an efficient means of elution which is not denaturing to neither the purified enzyme nor the immunoadsorbent column. Common properties of the microvillar enzymes with regard to amphiphilicity, glycosylation or subunit composition could hypothetically account for the similar elution properties of the enzymes but were considered unlikely on several grounds. Hypotonic elution in immunoadsorbent chromatography, therefore, may have a much broader range of applicability, and the method is recommended to be tried out by workers in other areas of protein chemistry.
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PMID:Hypotonic elution, a new desorption principle in immunoadsorbent chromatography. 612 6

Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.
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PMID:Structure of microvillar enzymes in different phases of their life cycles. 613 6

In the pigeon, 70-80% of the activities of maltase (alpha-D-glucoside glucohydrolase EC 3.2.1.20), sucrase (alpha-glucohydrolase, EC 3.2.1.48), isomaltase (dextran 6-alpha-D-glucan hydrolase, EC 3.2.1.10) and glucoamylase (1,4-alpha-D-glucan glucohydrolase, EC 3.2.1.3) were found to be localized in the brush-border membrane of intestinal epithelial cells. Of the total glycosidase activities in the mucosal homogenate, nearly 60 to 70% were recovered in the microsomal (105 000 X g) fraction, about 30% in the mitochondrial (22 000 X g) fraction and less than 5% from the cytosol (105 000 X g supernatant) fraction. The hydrolases were solubilized by digestion with papain but not with trypsin, and the phosphate ion had a protective effect in the solubilization. Amongst detergents, Triton X-100 but not sodium deoxycholate, was found to truly solubilize these enzymes.
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PMID:Studies on the intestinal disaccharidases of the pigeon. II. Subcellular localization and solubilization. 618 28

Sucrase-isomaltase (S-I) and maltase-glucoamylase (M-G) of the brush border have been purified to electrophoretic homogeneity from the pigeon small intestine. Heat-inactivated enzymes of crude homogenates of the pigeon intestinal mucosa, papain-solubilized enzymes and those obtained after chromatographic fractionation behaved in an identical manner. Depending on their sensitivity to heat treatment, the disaccharidases were identified to consist of two maltases; one, the heat-labile maltase, and the other, the heat-stable maltase. Sucrase and isomaltase constituted the thermolabile maltase and could be distinguished from each other. Maltase and glucoamylase formed the thermostable maltase the activities of which however, remained inseparable. Based on these results and in accordance with the nomenclature suggested by Dahlqvist & Telenius (1969), the pigeon intestinal disaccharidases were classified as follows: Maltase Ia = isomaltase, Maltase Ib = sucrase, and Maltase II = glucoamylase. DEAE-Cellulose chromatography did not resolve the two enzyme complexes but gel filtration of the active fractions recovered from the former step, resulted in their separation into two distinct peaks. Sucrase, isomaltase and a part of the maltase activity were recovered in the first peak which eluted close to the void volume. Glucoamylase and the remaining maltase activity were recovered in the second peak which appeared to have been retarded on the column because they were eluted much more slowly. The S-I and M-G complexes have an apparent molecular weight of 195 kd and 209 kd as determined by their gel-filtration pattern on Sepharose 6B. S-I hydrolysed alpha-glucosides such as maltose, sucrose and palatinose with a Km of 3.12 mM, 8 mM and 8.36 mM respectively and did not attack starch or dextran. In contrast, M-G catalysed the hydrolysis of starch, amylose and maltose with a Km of 3.12 mM, 7.59 mM and 3.52 mM respectively, and had no action on sucrose or palatinose. Both S-I and M-G were glycoproteins, and were inhibited by Ag+, Hg2+ and Tris but not by p-hydroxymercuribenzoate, iodoacetamide or imidazole. Na+ on the other hand activated both the enzyme complexes by about 20-25%. It is suggested that the molecular and catalytic properties of intestinal disaccharidases of pigeons do not differ considerably from those of Mammals.
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PMID:Studies on the intestinal disaccharidases of the pigeon. III. Separation, purification and properties of sucrase-isomaltase and maltase-glucoamylase. 620 6

Antisera against purified pigeon small intestinal sucrase-isomaltase (S-I) and maltase-glucoamylase (M-G) were prepared from rabbits. Both sera showed cross-reactivity. It was demonstrated that the sucrase . isomaltase was purified to homogeneity, supporting our earlier results of SDS-PAGE of pigeon intestinal disaccharidases. Both the sucrase- isomaltase and maltase-glucoamylase activities were not inhibited by either specific or cross-reacting antibodies even when a several fold of either antibody was present. It is inferred from these immunochemical results that the two complexes in the pigeon intestine share many structural identities, and that their catalytic site(s) may not be involved in their antigenic domains.
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PMID:Studies on the intestinal disaccharidases of the pigeon IV. Immunochemical properties of sucrase . isomaltase and maltase . glucoamylase. 620 7

Antibodies against 3 purified human small intestinal brush-border hydrolases (sucrase-isomaltase, maltase-glucoamylase and neutral aminopeptidase) were produced in rabbits. By double immunodiffusion and crossed immunoelectrophoresis the antisera appeared to be monospecific. However, with the immunoblotting method antibodies reacting with many brush-border proteins were detected. In one case, the cross-reactions were due to the presence of anti-A antibodies. In other cases absorption of the antisera with absorbants with blood group A and H activities did not eliminate these reactions. As the main brush-border proteins are glycosylated and share common lectin reactivities, it is possible that these antibodies are directed against carbohydrate antigens. The use of such antibodies for immunocytochemical methods and for immunoassays must be undertaken with caution. These principles are applicable to other antigen systems.
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PMID:Antigenic cross-reactions among human intestinal brush-border enzymes revealed by the immunoblotting method and rabbit anti-enzyme sera. 620 83

The effects of sucrose and Acarbose (alpha-glucosidase inhibitor) feeding on the development of diabetes were studied in streptozotocin-treated rats. Rats were raised on four different dietary regimens, viz, a sucrose diet (46% of the total weight in the form of sucrose, 24% as starch), a starch diet (70% as starch), a standard diet (laboratory chow: Oriental Yeast Co.) or an Acarbose diet (a standard diet containing 75 mg Acarbose/100g diet) for a week followed by an intraperitoneal injection of streptozotocin (70 mg/kg). Development of diabetes was determined by urinary and blood glucose levels (more than 250 mg/dl). The incidence of diabetes in the groups of rats fed on sucrose, starch, standard, and Acarbose diets was 100%, 80%, 70% and 47.6%, respectively. The development of diabetes was accelerated by sucrose feeding and depressed by Acarbose feeding. There was mild diabetes in rats fed on Acarbose diet. The sucrose feeding caused a marked increase of disaccharidase activities in the proximal part of the intestine and in the apical part of the villus-crypt gradient of epithelial cells. The Acarbose feeding caused a significant decrease of disaccharidase activities. The changes in protein content of the sucrase-isomaltase complex appeared to be in parallel with those of disaccharidase activities. These results suggest that intestinal disaccharidase activities are involved in the development of experimental diabetes induced by streptozotocin.
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PMID:Effect of sucrose and Acarbose feeding on the development of streptozotocin-induced diabetes in the rat. 621 54

Mucosa from the duodenal and jejunal regions of pig small intestine was repeatedly freeze-thaw treated to solubilize an enzyme preparation, enriched in maltase, glucoamylase and alpha-limit dextrinase activities; isomaltase and sucrase remained essentially insoluble during the treatment. Chromatographic procedures, including ion-exchange, gel filtration and hydroxylapatite chromatography of the solubilized preparation, brought to homogeneity an alpha-glucosidase active towards maltose, alpha-limit dextrins and starch in decreasing order, with only a very weak capacity to hydrolyse alpha-1,6-linkages. Michaelis constants and maximal velocities, as well as relative rates of hydrolysis of several substrates, including maltodextrins and alpha-limit dextrins, were determined and served to characterize what seems to be a rather specific alpha-1,4-glucosidase. The participation of this enzyme in the hydrolysis of alpha-limit dextrins and more generally in pathways for starch breakdown in the pig digestive tract is examined and discussed.
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PMID:Purification and characterization of a pig intestinal alpha-limit dextrinase. 633 42


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