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)

Brush border fragments (BBF) were isolated from homogenates of intestinal epithelium prepared from four groups of tadpoles: premetamorphic larvae, thyrostatic larvae, spontaneously metamorphosed larvae, and triiodothyronine (T3)-induced froglets. Isolation was accomplished by a combination of both Ca2+ precipitation and differential centrifugation methods. These preparations were routinely enriched seven- to-eleven-fold for the two amphibian brush border marker enzymes, gamma-glutamyltransferase and maltase. Comparison by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with silver staining revealed the presence of a polypeptide of Mr 27,000 only after spontaneous and T3-induced metamorphosis. One-dimensional SDS-PAGE together with lectin staining showed six strongly concanavalin A reactive polypeptides (Mr 52,000, 57,000, 65,000, 80,000, 130,000 and 150,000) in both preparations examined. Immunoblot analyses allowed us to detect in both preparations the presence of villin (Mr 105,000), a cytoskeletal component of microvilli. Two-dimensional isoelectric focusing IEF/SDS-PAGE together with silver staining showed the polypeptides of Mr 41,500, 43,000, 60,500 and 101,000 to be specific components of the primary intestinal epithelium brush border. In contrast six polypeptides of Mr 27,000, 52,000, 58,000, 59,000 and 95,000 were only detected in intestinal BBF after spontaneous and T3-induced metamorphosis. Their presence is under the control of the thyroid hormone. The results provide new insight regarding the subcellular localization of polypeptides whose synthesis changes during spontaneous (Figiel et al., 1987) and T3-induced metamorphosis (Figiel et al., 1989).
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PMID:Influence of triiodothyronine on the polypeptide composition of the intestinal brush border membrane during amphibian metamorphosis. 198 Nov 41

Administration of Embelin, an experimental antifertility agent, to male rats (20 mg/kg body wt/day, daily for 15 and 30 days), caused an elevation in the uptake of D-glucose, L-alanine, L-leucine, and calcium in the small intestinal segments. An increase was also noted in the intestinal brush border membrane (BBM)-associated enzymes, sucrase, lactase, maltase, alkaline phosphatase, and leucine aminopeptidase in both the intestinal homogenates and partially purified BBM preparations, particularly after 30-day administration of the drug. Embelin treatment also caused a significant increase in the microsomal glucose-6-phosphatase and the cytosolic enzyme, lactate dehydrogenase. In the Embelin-treated animals BBM-associated total lipids, phospholipids, cholesterol, triacylglycerol, unesterified fatty acids, ganglioside-sialic acids as well as the cholesterol/phospholipids molar ratio showed a considerable increase. All these changes in the Embelin-treated animals were restored back to the normal or near normal biochemical makeup when the drug therapy was withdrawn and the animals were allowed to recover for another 15 and 30 days, respectively.
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PMID:Changes in glucose/amino acid/calcium uptake and brush-border membrane-associated enzymes in rat small intestine after the administration of embelin (plant benzoquinone), an antifertility agent. 211 47

1. Boar semen was separated on a Percoll density gradient into three populations; a low-density band of immature sperm cells containing a cytoplasmic droplet and a high-density doublet band formed by spermatozoa without a cytoplasmic droplet. 2. In these three cell populations four acid hydrolases were determined, viz. (1) alpha-glucosidase; (2) alpha-mannosidase; (3) beta-galactosidase; (4) beta-hexosaminidase. 3. The release of the hydrolases (1), (2) and (3) from cytoplasmic droplet containing spermatozoa was stimulated whereas the release of beta-hexosaminidase was inhibited by calcium ions. 4. The results suggest that acid alpha-glucosidase, alpha-mannosidase and beta-galactosidase are situated in the acrosome whereas acid beta-hexosaminidase is localized predominantly in the cytoplasmic droplet of boar spermatozoa. 5. We conclude that beta-hexosaminidase should prove useful as a biochemical marker for cytoplasmic droplet containing spermatozoa and hence for the number of immature sperm cells in boar semen.
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PMID:Isolation and characterization of boar spermatozoa with and without a cytoplasmic droplet. 214 Aug

Predictions of protein secondary structure are used with amino acid sequence alignments to show that the N-terminal domains of cyclodextrin glucanotransferases and a yeast alpha-glucosidase may have the same super-secondary structure as alpha-amylases, i.e. an (alpha/beta)8-barrel fold. Sequence similarities provide evidence that glucanotransferases, and possibly the glucosidase, are, like alpha-amylases, Ca2+-containing enzymes. The relationship between substrate specificity and the nature of the amino acid residues proposed at the active site is discussed for the transferases and alpha-glucosidase. A set of three programs for an Apple IIe computer to carry out the calculations described by Garnier, Osguthorpe & Robson [(1978) J. Mol. Biol. 120, 97-120] and a set of four programs for an Apple IIe computer to carry out the calculations described by Levin, Robson & Garnier [(1986) FEBS Lett. 205, 303-308] have been deposited as Supplementary Publication SUP 50149 (25 pages) at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1989) 257, 5.
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PMID:A super-secondary structure predicted to be common to several alpha-1,4-D-glucan-cleaving enzymes. 252 86

The effects of Gossypol acetic acid (10 mg/kg b. wt. daily for 15 days), an experimental male antifertility agent and its subsequent withdrawal for another 15 days, on the structure and functions of the rat small intestinal tract have been investigated. Gossypol feeding causes a reduction in body weight and intestinal weight, length, protein, and nucleic acid contents. A 27%-50% reduction in the uptake of glucose, alanine, leucine, and calcium is observed after Gossypol feeding which is found to be reversible after 15 days of withdrawal of the drug. Gossypol also causes a significant reduction in the activities of sucrase, lactase, maltase and alkaline phosphatase in the intestinal homogenates as well as in the purified brush border membrane of the microvillus. A decrease in the maximum of apparent enzyme velocity and no change in the substrate affinity constant in these digestive hydrolases are observed on Gossypol treatment. It also causes a shift in the transition temperature in these enzymes and predictably changes the energy of activation both below and above the temperature of transition, although the Arrhenius expression of the temperature dependence still shows proximity, non-linearity, and is parallel to the control group. These changes are reversed on withdrawal of the drug and during the subsequent recovery period. Recovery experiments also show near identical values in kinetic parameters (Kt and Jmax) of 14C-glucose uptake in jejunal segments both in the presence and absence of Na+ ions. Also, no difference is observed between the control and recovery groups with respect to body and intestinal weight, intestinal length, and DNA, RNA, protein, lactate dehydrogenase and glucose-6-phosphate phosphohydrolase values in the intestinal homogenates. Phospholipid, cholesterol and sialic acid levels in both the groups also show nearly identical values. Molecular mechanism of the effects of Gossypol on brush border membrane-bound enzyme/carrier molecules operation is discussed in view of the kinetic and thermodynamic data obtained.
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PMID:Reversibility of the effects of gossypol acetic acid, an antispermatogenic/antifertility agent on the intestinal structure and functions of male albino rats. 274 9

Chemical galactosylation of human liver tissue lysosomal alpha-glucosidase was carried out. As a result of the modification some physicochemical properties of the enzyme were altered, while its stability and catalytic activity were maintained. An ability of the galactosylated alpha-glucosidase to interact with asialoglycoprotein receptor from mice liver tissue was studied in vitro. The reaction required Ca2+. A specific inhibitor of the receptor, N-acetyl galactosamine, as well as high concentrations of native glycoproteins and neoglycoproteins containing terminal galactose inhibited the receptor binding of the 125I-galactosylated alpha-glucosidase. Native alpha-glucosidase was not bound with the receptor. Antireceptor antibodies inhibited similarly binding of both native ligand, asialoorosomucoid and the galactosylated alpha-glucosidase. These data on specific interaction between the galactosylated form of alpha-glucosidase and asialoglycoprotein receptor are discussed in connection with the problem of directed transport of the enzyme into liver parenchymatous cells by means of receptor-dependent endocytosis, which may be of importance in development of enzymotherapy of hereditary lysosomal enzymopathies.
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PMID:[Chemical galactosylation of acid alpha-glucosidase to provide directed transport of the enzyme into lysosomes of liver parenchymal cells]. 282 27

Present evidence suggests that in the small intestine, villus cells are primarily absorptive and crypt cells are primarily secretory. In order to further confirm that there are differences in transport properties between villus and crypt cells, we have separated villus from crypt cells, using calcium chelations techniques, and determined the distribution of Na:H and Cl:HCO3 exchange activity on brush border membrane and basolateral membrane preparations from these two cell populations. Separation of cells was determined utilizing alkaline phosphatase and maltase activity as a marker of villus cells and thymidine kinase activity as a marker of crypt cells. Utilizing these techniques, we were able to sequentially collect cells along the villus-crypt axis. Na-stimulated glucose and alanine uptake in brush border membrane vesicles diminished from the villus to the crypt region in the sequentially collected cells fractions, further suggesting separation of these cells. Brush border and basolateral membranes were then prepared from cells from the villus and crypt areas, utilizing a continuous sucrose gradient. In the villus cells, Na:H exchange activity was found associated with both the brush border and basolateral membrane, whereas, in crypt cells, Na:H exchange activity was only found on the basolateral membrane. Cl:HCO3 exchange activity was found only on the brush border membrane, in both villus and crypt cells. These studies suggest functional heterogeneity in ion transport between villus and crypt cells.
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PMID:Membrane distribution of sodium-hydrogen and chloride-bicarbonate exchangers in crypt and villus cell membranes from rabbit ileum. 284 68

By use of a radiometric assay transglutaminase activity was demonstrated for the first time in human jejunal mucosa. The activity is similar to that in other tissues, with a pH optimum of 9.0, an absolute requirement for Ca2+ and an apparent Km for putrescine of 0.15 mmol/l. Assay of jejunal transglutaminase activity with a variety of dietary proteins as acceptors showed high activity with gliadin, comparable with that of the standard substrate, dimethylcasein. Deamidation of the gliadin markedly reduced its acceptor activity. Collagen, ovalbumin, elastin and zein exhibited very low acceptor activities. Increased transglutaminase activity was demonstrated in jejunal biopsies from four patients with untreated coeliac disease compared with 14 control subjects and eight patients with inflammatory bowel disease. Eight patients with coeliac disease in remission, with normal levels of brush border alpha-glucosidase, showed elevated transglutaminase activities compared with those of controls. It is postulated that intestinal transglutaminase activity may be important in gliadin binding to tissues and thus in the pathogenesis of coeliac disease.
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PMID:Human jejunal transglutaminase: demonstration of activity, enzyme kinetics and substrate specificity with special relation to gliadin and coeliac disease. 285 82

The intestinal microvilli of fetal origin in human amniotic fluid were purified by Ca2+ precipitation of contaminating organelles followed by differential centrifugation of microvillar membranes. In the purified preparation, the specific activity of the microvillar marker-enzymes maltase and sucrase increased about 77-fold over that in cell-free amniotic fluid. Significant contamination of the purified preparation by endoplasmic reticulum (microsomes) and lysosomes was ruled out on the basis of a low content of the marker enzymes glucose-6-phosphatase (microsomes) and acid phosphatase (lysosomes). Amniotic fluid microvilli contain typical enzymes of the fetal intestine including maltase, sucrase, trehalase, alkaline phosphatase and gamma-glutamyltransferase, and their morphology by electron microscopy resembles that of vesiculated intestinal microvilli. Prenatal detection of genetic diseases due to a deficiency of a protein expressed in these membranes or associated to abnormal microvilli seems feasible.
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PMID:Fetal intestinal microvilli in human amniotic fluid. 302 83

The function of membrane cholesterol (chol) in the regulation of membrane-bound hydrolases and transport proteins has been investigated in chol-enriched membranes of guinea pig intestinal brush borders. Chol-enrichment is accomplished by non-invasive means i.e., dietary manipulation by high-chol diet feeding. Activities of sucrase, lactase and maltase enzyme systems, Na+-dependent and -independent glucose transport and calcium uptake are found to be greatly inhibited by chol both at 22 degrees C and 37 degrees C. Glucose and calcium uptake in native membranes are found to be temperature sensitive processes and produce nonlinear Arrhenius plots with a transition temperature around 22 degrees C. The discontinuity in the Arrhenius expression is lost in chol enriched membranes which is interpreted as the increase in microviscosity imparted by chol in the bulk lipid phase environment where these proteins operate.
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PMID:Effect of cholesterol and temperature perturbations on membrane hydrolases and transport of calcium and glucose in guinea pig brush border membrane vesicles. 317 55


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