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)

Hypertension is an important risk factor for atherosclerosis and often occurs in association with diabetes mellitus. Specific activities of hydrolases in homogenates of aortas from rats with renal-clip hypertension, normotension following a period of hypertension, and hypertension combined with streptozotocin-induced diabetes mellitus were measured. Enzymes included: neutral alpha-glucosidase, and lysosomal N-acetyl-beta-glucosaminidase, beta-galactosidase, cathepsin C, acid alpha-glucosidase, and acid cholesteryl esterase. After 6 or 12 weeks of hypertension, specific activities of all enzymes measured were significantly increased, levels ranging from 24% above normal for cathepsin C to 351% above normal for N-acetyl-beta-glucosaminidase. Six weeks of normotension following 6 weeks of hypertension resulted in restoration to normal of four of the six enzyme activities; the remaining two enzymes were significantly below normal levels. Combined hypertension and diabetes mellitus showed smooth muscle cell levels of four of the five hydrolases measured to be significantly lower than those present with hypertension alone. In every instance, histochemical studies of aortas showed acid phosphatase and N-acetyl-beta-glucosaminidase activities which corresponded to the biochemical findings. These findings indicate profound and discrete effects of two clinical risk factors on vascular smooth muscle cell lysosomes.
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PMID:Hydrolase activities in the rat aorta. II. Effects of hypertension alone and in combination with diabetes mellitus. 65 43

1. Fragments (2-20 mg wet wt.) of closed needle-biopsy specimens from human liver were disrupted in iso-osmotic sucrose and subjected to low-speed centrifugation. The supernatant was layered on a linear sucrose-density gradient in the Beaufay small-volume automatic zonal rotor. The following organelles, with equilibrium densities (g/ml) and principal marker enzyme shown in parentheses, were resolved: plasma membrane (1.12-1.14; 5'-nucleotidase); lysosomes (1.15-1.20; N-acetyl-beta-glucosaminidase); mitochondria (1.20; malate dehydrogenase); endoplasmic reticulum (1.17-1.21; neutral alpha-glucosidase); peroxisomes (1.22-1.24; catalase). 2. The distribution of particulate alkaline phosphatase and, to a lesser degree, leucine 2-naphthylamidase followed that of 5'-nucleotidase. gamma-Glutamyltransferase was associated with membranes of significantly higher equilibrium density than was 5'-nucleotidase. 3. The distribution of 12 acid hydrolases was determined in the density-gradient fractions. beta-Glucosidase had a predominantly cytosolic localization, but the other enzymes showed a broad distribution of activity throughout the gradient. Evidence was presented for two populations of lysosomes with equilibrium densities of 1.15 and 1.20 g/ml, but containing differing amounts of each enzyme. Further evidence of lysosomal heterogeneity was demonstrated by studying the distribution of isoenzymes of hexosaminidase and of acid phosphatase. 4. The resolving power of the centrifugation procedure can be further enhanced with membrane perturbants. Digitonin (0.12 mM) selectively disrupted lysosomes, markedly increased the equilibrium density of plasma-membrane components and lowered the density of the endoplasmic reticulum, but did not affect the mitochondria or peroxisomes. Pyrophosphate (15 mM) selectively lowered the equilibrium density of the endoplasmic reticulum.
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PMID:Analytical subcellular fractionation of needle-biopsy specimens from human liver. 70 96

Activities of the small intestinal mucosal enzymes lactase, sucrase, maltase, alkaline phosphatase and N-acetyl-beta-glucosaminidase were studied in rats with surgically-induced upper intestinal stasis and in control animals. The first four are brush border enzymes, the latter a lysosomal enzyme. There was a reduction in the activities of all enzymes in the operated animals. The change lining was significant and most marked in mucosa the blind loop and gut distal to it; areas in which there is gross bacterial overgrowth and excessive levels of intraluminal deconjugated bile salts. The significance of these findings in relation to malabsorption consequent on bacterial contamination of the upper gut is uncertain and requires further study.
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PMID:Effect of stasis on intestinal enzyme activities. 105 24

Feeding sodium deoxycholate orally to rats for four days caused depression of the activity of the small intestinal enzymes lactase, sucrase, maltase, alkaline phosphatase, and N-acetyl-beta-glucosaminidase. The first four are brush border enzymes, the last a lysosomal enzyme. Alkaline phosphatase activity recovered very rapidly and rebounded to above the normal level within 24 hours. The activity of the three disaccharidases returned to normal within seven days while no recovery was observed within 96 hours of the activity of the lysosomal enzyme, N-acetyl-beta-glucosaminidase, after removing the bile salt from the diet.
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PMID:Deoxycholate depresses small-intestinal enzyme activity. 114 Jun 27

Adrenalectomy performed on 14-day-old rats delayed the usual increase of sucrase and maltase activity as well as the decrease of acid beta-galactosidase, beta-glucuroindase and N-acetyl-beta-glucosaminidase activity during the third postnatal week. Since these changes were only delayed, the role of the thyroid was explored. Thyroidectomy performed simultaneously with adrenalectomy on 14-day-old rats did not influence the increase in body weight and growth of the small intestine (already slowed down by adrenalectomy), but caused a further substantial delay in the maturation of the enzyme profile of the small intestine. Our results indicate that the thyroid is involved in regulation of the hydrolases studied.
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PMID:Effect of thyroidectomy on the activity of alpha-glucosidases and acid hydrolases in the small intestine of rats during weaning. 116 38

Diversion of portal blood in congenital portosystemic shunts (CPSS) results in liver atrophy and passage of toxins into the systemic circulation causing hepatic encephalopathy. In some dogs, there is indirect evidence for hepatic insufficiency, but histologic findings are equivocal. This study determined whether hepatocyte integrity in PSS is comprised at a subcellular level using analytical subcellular fractionation of liver biopsies. Six dogs with CPSS had hypoproteinemia (6/6), increased serum alkaline phosphatase (6/6) and alanine aminotransferase (4/6) activity, hypocholesterolemia (6/6), and decreased blood urea (2/6). Liver biopsy specimens had increased activities (mU/mg protein) of alkaline phosphatase (17.9 +/- 10.1; controls 5.1 +/- 5.3: P less than 0.01), but not of other plasma membrane enzymes. There were increased activities of endoplasmic reticular (neutral alpha-glucosidase: 1.67 +/- 0.7; controls 0.86 +/- 0.2: P less than 0.01) and lysosomal enzymes (N-acetyl-beta-glucosaminidase: 12.6 +/- 2.3; controls 6.24 +/- 2.7: P less than 0.01; alpha-mannosidase: 0.85 +/- 0.5; controls 0.39 +/- 0.3: P less than 0.05). Subcellular fractionation on reorientating sucrose density gradients showed a high-density peak of alkaline phosphatase suggestive of a specific increase in the biliary canalicular component of enzyme activity. Neutral alpha-glucosidase was shifted to denser fractions, indicative of an increase in the proportion of rough-to-smooth endoplasmic reticulum and consistent with enhanced synthesis of membranous enzymes. There was also evidence for increased fragility of intracellular organelles, particularly lysosomes. In contrast, histology showed either no abnormalities or minor degenerative changes compatible with hepatic underperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic organelle pathology in dogs with congenital portosystemic shunts. 161 98

To further document the effect of insulin on intestinal maturation, suckling rats were treated either with exogenous insulin (12.5 mU.g body wt, intraperitoneally, twice daily) or with saline from d 8 to 12 postpartum. Sucrase activity in brush border membrane extracts was precociously induced by insulin, whereas the activities of other brush border membrane enzymes (maltase, aminopeptidase, and neutral lactase) were enhanced (+ 30 to + 131%, p less than 0.01 versus controls). The lysosomal enzyme, N-acetyl-beta-glucosaminidase, which normally declines at weaning was significantly (p less than 0.025) decreased in both villus (-51%) and crypt cells (-57%) isolated from the jejunum of insulin-treated rats. The microsomal enzyme, sulfatase C, and the cytosolic enzyme, lactate dehydrogenase, were also sensitive to insulin with decreases in activity ranging from -37 to -63% (p less than 0.05) compared to saline-treated control rats. Insulin at doses of 0.5 or 12.5 mU did not influence plasma total corticosterone levels, which were about 9-fold lower in suckling than in 25-d-old weaned rats. In weaned rats (from d 25 to 32) insulin treatment (12.5 mU) failed to influence the activity of brush border membrane hydrolases or of lysosomal, microsomal, and cytosolic enzymes. The synthesis rate of mature sucrase-isomaltase, measured in weaned rats (32 d) by the incorporation of 14C-leucine into the enzyme precursor protein, was equivalent in both groups. These data demonstrate that the immature enterocyte of the suckling rat is responsive to insulin, whereas the mature enterocyte of the weaned rat is unresponsive.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hormonal regulation of the rat small intestine: responsiveness of villus and crypt cells to insulin during the suckling period and unresponsiveness after weaning. 217 34

1. Tests for glycosidases were performed in homogenates of Brachionus plicatilis. 2. Hydrolytic activity was detected with the following substrates: (a) with synthetic substrates (NP = 4-nitrophenyl): NP-alpha- and NP-beta-D-glucopyranoside, NP-alpha- and NP-beta-D-galactopyranoside, NP-N-acetyl-beta-D-glucosaminide, NP-N-acetyl-beta-D-galactosaminide, NP-alpha- and NP-beta-D-mannopyranoside and NP-alpha-L-fucopyranoside; (b) with disaccharides: sucrose, maltose, trehalose, isomaltose, cellobiose, gentiobiose and lactose; (c) with polysaccharides: laminarine, carboxymethyl-cellulose, avicel, Micrococcus luteus (for lysozyme) and 4-nitrophenyl-alpha-D-maltoheptaoside (for amylase). 3. The pH dependence of the glycosidase activities was determined. 4. The distribution of enzyme activities within fractions from the homogenate was studied in order to localize them within the cell. 5. Proteins from Brachionus homogenate were separated by SDS-gel electrophoresis and the positions of the following glycosidase activities were detected by assays performed on the gels (estimated molecular weights in parentheses): alpha-glucosidase (250,000); beta-glucosidase (200,000); beta-galactosidase (70,000); N-acetyl-beta-glucosaminidase (60,000).
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PMID:Glycosidases in Brachionus plicatilis (Rotifera). 232 73

Phosphoglycans from the cell wall of many strains of Streptococci contain terminal carbohydrate units linked by phosphodiester bridges to other residues of the glycans. In the immune response to phosphoglycans, the terminal carbohydrate-phosphate moieties function as antigenic determinants and induce the synthesis of antibodies with specificity for the glycosyl-phosphoryl units. It has now been found that such terminal carbohydrate units can be removed by treatment of the glycans with appropriate glycosidases. Thus, an almond beta-glucosidase releases glucose from a streptococcal Group D phosphoglycan with beta-glucosyl phosphate units, a jack bean N-acetyl-beta-glucosaminidase releases N-acetylglucosamine from a streptococcal Group L phosphoglycan with N-acetyl-beta-glucosaminyl phosphate units, and a rice alpha-glucosidase releases glucose from a yeast phosphoglycan with alpha-glucosyl phosphate units. The glycosidases also hydrolyze the hexose phosphates of the proper anomeric configuration and structure. The preparations of glycosidases used in this study exhibit specificity for single types of carbohydrate residues and are devoid of phosphatase and phosphodiesterase activities. The glycosidases act on glycosyl-phosphoryl linkages by a stereospecific mechanism and can therefore be used for the determination of the anomeric configuration of glycosyl-phosphoryl units of complex carbohydrates.
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PMID:The determination of the anomeric configuration of glycosyl-phosphoryl linkages of immunogenic phosphoglycans. 240 37

Adler and Martin (1983, Curr. Eye Res. 2, 359-66) found cathepsin D to be present in crude preparations of bovine interphotoreceptor matrix (IPM). The purpose of the present study was to determine, by investigating several acid hydrolases in purer IPM samples, whether hydrolytic enzymes abundant in RPE lysosomes were present also as normal components of the IPM. IPM was prepared from bovine eyes by the introduction of a small bleb of buffer between the neural retina and the RPE. These IPM samples were free from significant contamination by surrounding tissues; they contained IRBP as their only major protein, and had negligible amounts of lactate dehydrogenase and ROS-specific proteins. Most acid hydrolases were assayed fluorometrically by measuring the 4-methylumbelliferone released upon hydrolysis of appropriate derivatives; the substrate for cathepsin was hemoglobin. The amounts of the enzymes found in the IPM were far from uniform and could not be correlated with enzyme activities in either RPE or retina homogenates. The hydrolases in the IPM varied in amount from beta-galactosidase (28% of the RPE level), through N-acetyl-beta-glucosaminidase (20%), alpha-fucosidase (15%), beta-glucuronidase (12%), alpha-glucosidase (8%), cathepsin D (7%), alpha-mannosidase (7%), down to beta-glucosidase, acid phosphatase, and acid lipase (trace amounts, less than 1%). These results agree with the relative amounts of enzymes found by Wilcox (1987) to be secreted into the medium by cultured human RPE cells. Furthermore, the rank order of hydrolases in the IPM is the same as that for hydrolases secreted (but not recaptured) by human fibroblasts in I-cell disease. The conclusion from these correlations is that lysosomal enzymes are probably secreted, as a normal process, by the RPE into the IPM, where they may have a role in digesting shed outer segments and in catabolizing IPM components.
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PMID:Selective presence of acid hydrolases in the interphotoreceptor matrix. 261 85


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