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)

In vivo jejunal transport of amino acids, monosaccharides, sodium, and electrolytes were studied in rats made nephrotic with puromycin aminonucleoside (PAN) and in pair-fed controls. Studies were performed 14 days after a single intravenous dose of PAN when rats were no longer edematous, but were still hypoproteinemic. There was decreased absorption of glucose, 3-0-methyl glucose, glycine, phenylalanine, histidine, water, and sodium in the nephrotic animals but transport of fructose, lysine and potassium was similar in the nephrotic and control animals. Enzyme kinetic studies for glucose transport showed a mixed type of inhibition affecting both Vm and Km. The jejunal mucosa of nephrotic and control rats had similar ATP content and enzyme activity for lactase, sucrase, maltase and (Na-K)-ATPase and the ratios of RNA to DNA were similar in the nephrotic and control rats. No abnormality of the jejunum was detected by light or electron microscopy. The data suggest that the impairment of absorption is a result of decreased activity of jejunal membrane carrier mechanisms. The altered transport may be secondary to effects related to the metabolic consequences of nephrotic syndrome and does not appear to be related to acute purine aminonucleoside toxicity, edema or malnutrition.
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PMID:Jejunal transport in experimental nephrotic syndrome. 662 9

We have studied the dependence on mitochondrial ATP of expression of MAL genes specifying maltose utilization in yeast. It was found that bongkrekic acid does not prevent the maltose induced synthesis of alpha-glucosidase in derepressed cells of the wild-type and corresponding respiratory-deficient mutant of Saacharomyces cerevisiae. The results suggest that expression of nuclear genes specifying alpha-glucosidase and maltose catabolism in yeast is apparently not dependent on the proper function of mitochondrial adenine nucleotide translocase and does not even require the presence of normal levels of ATP in mitochondria.
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PMID:Alpha-glucosidase synthesis in yeast cells depleted of intramitochondrial ATP. 700 49

We have studied the effects of the Sulfolobus solfataricus chaperonin on the aggregation and inactivation upon heating of four model enzymes: chicken egg white lysozyme (one 14.4-kDa chain), yeast alpha-glucosidase (one 68.5-kDa chain), chicken liver malic enzyme (four 65-kDa subunits), and yeast alcohol dehydrogenase (four 37.5-kDa subunits). When the proteins were heated in the presence of an equimolar amount of chaperonin, 1) the aggregation was prevented in all solutions; 2) the inactivation profiles of the single-chain enzymes were comparable with those detected in the absence of the chaperonin, and enzyme activities were regained in the solutions heated in the presence of the chaperonin upon ATP hydrolysis (78 and 55% activity regains for lysozyme and alpha-glucosidase, respectively); 3) the inactivation of the tetrameric enzymes was completely prevented, whereas the activities decreased in the absence of the chaperonin. We demonstrate by gel filtration chromatography that the chaperonin interacted with the structures occurring during thermal denaturation of the model proteins and that the interaction with the single-chain proteins (but not that with the tetrameric proteins) was reversed upon ATP hydrolysis. The chaperonin had nonequivalent surfaces for the binding of the model proteins upon heating: the thermal denaturation intermediates of the single-chain proteins share Surfaces I, while the thermal denaturation intermediates of the tetrameric proteins share Surfaces II. ATP binding to the chaperonin induced a conformation that lacked Surfaces I and carried Surfaces II. These data support the concept that chaperonins protect native proteins against thermal aggregation by two mechanistically distinct strategies (an ATP-dependent strategy and an ATP-independent strategy), and provide the first evidence that a chaperonin molecule bears functionally specialized surfaces for the binding of the protein substrates.
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PMID:Prevention of in vitro protein thermal aggregation by the Sulfolobus solfataricus chaperonin. Evidence for nonequivalent binding surfaces on the chaperonin molecule. 749 1

beta-Fructofuranosidase, alpha-glucosidase, beta-glucosidase, alpha-mannosidase, beta-mannosidase, sucrose phosphorylase, glucosyltransferase and fructosyltransferase were separated by isoelectric focusing and sensitively detected to be slightly diffuse and insoluble spots in thin-layer gels, supported by a glass plate, by release of monosugars or a sugar phosphate, followed by conversion to glucose-6-phosphate (G6P) and then by reduction of NADP+ to NADPH, terminated by the formation of reduced Nitroblue Tetrazolium (NBT). Approximately 1-10 mU of enzyme was focused and the gel, after washing with a buffer, was partially dried and directly stained by uniformly spreading on the gel surface a staining medium containing sucrose or nitrophenyl glycosides as substrates, intermediary enzymes such as hexokinase, mutase and/or isomerase, NADP+, ATP, Mg+, phenazine methosulfate (PMS) and NBT. Specific staining procedures for each of these activities, on sucrose or on the glycosides as substrates, and staining procedures for multiple activities are described, with the conditions necessary for optimal development.
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PMID:Glucose, fructose, mannose and/or glucose-1-phosphate-releasing activity stains for glycosidases and glycosyltransferases in gels after isoelectric focusing. 751 61

Previous studies in very young rats have shown that dietary nucleotides improve small intestine repair after injury or malnutrition. To investigate the potential effect of nucleotides in old rats, which have a diminished capability for intestinal repair, 17-mo-old rats were deprived of food for 5 d and then fed a nucleotide-free diet or a nucleotide-supplemented diet for 3 or 6 d. Intestinal jejunal and ileal mucosal weight, protein and DNA were evaluated as intestinal growth markers, and brush-border maltase, sucrase, lactase and aminopeptidase activities were evaluated as intestinal differentiation markers. The adenine nucleotide pool and the adenylate energy charge were also evaluated as indices of nucleotide availability. Food deprivation significantly decreased mucosal growth markers as well as differentiation markers in both jejunum and ileum. The ATP pool was also significantly depressed, but the adenylate energy charge was not significantly altered. To a certain extent, refeeding restored the losses, but in the rats that were fed the nucleotide-free diet, the restoration of the jejunum was significantly slower and the restoration of the ileum differentiation markers was incomplete compared with the rats fed the nucleotide-supplemented diet. The results suggest that dietary nucleotide intake in the elderly may accelerate the normal physiological intestinal response to refeeding after food deprivation.
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PMID:Dietary nucleotides accelerate intestinal recovery after food deprivation in old rats. 778 93

Small heat shock proteins (sHsp) with a molecular mass of 15-30 kDa are ubiquitous and conserved. Up to now their function has remained enigmatic. Increased expression under heat shock conditions and their protective effect on cell viability at elevated temperatures suggest that they may have a function in the formation or maintenance of the native conformation of cytosolic proteins. To test this hypothesis we studied the influence of murine Hsp25, human Hsp27, and bovine alpha-B-crystallin (an eye lens protein homologous to sHsps) on the unfolding and refolding of citrate synthase and alpha-glucosidase in vitro. Here we show that all sHsps investigated act as molecular chaperones in these folding reactions. At stoichiometric amounts they maximally prevent the aggregation of citrate synthase and alpha-glucosidase under heat shock conditions and stabilize the proteins. Furthermore, they promote the functional refolding of these proteins after urea denaturation similar to GroE and Hsp90. The interaction both with unfolding and refolding proteins seems to be ATP-independent.
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PMID:Small heat shock proteins are molecular chaperones. 809 12

In gram-positive bacteria, HPr, a phosphocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), is phosphorylated by an ATP-dependent, metabolite-activated protein kinase on seryl residue 46. In a Bacillus subtilis mutant strain in which Ser-46 of HPr was replaced with a nonphosphorylatable alanyl residue (ptsH1 mutation), synthesis of gluconate kinase, glucitol dehydrogenase, mannitol-1-P dehydrogenase and the mannitol-specific PTS permease was completely relieved from repression by glucose, fructose, or mannitol, whereas synthesis of inositol dehydrogenase was partially relieved from catabolite repression and synthesis of alpha-glucosidase and glycerol kinase was still subject to catabolite repression. When the S46A mutation in HPr was reverted to give S46 wild-type HPr, expression of gluconate kinase and glucitol dehydrogenase regained full sensitivity to repression by PTS sugars. These results suggest that phosphorylation of HPr at Ser-46 is directly or indirectly involved in catabolite repression. A strain deleted for the ptsGHI genes was transformed with plasmids expressing either the wild-type ptsH gene or various S46 mutant ptsH genes (S46A or S46D). Expression of the gene encoding S46D HPr, having a structure similar to that of P-ser-HPr according to nuclear magnetic resonance data, caused significant reduction of gluconate kinase activity, whereas expression of the genes encoding wild-type or S46A HPr had no effect on this enzyme activity. When the promoterless lacZ gene was put under the control of the gnt promoter and was subsequently incorporated into the amyE gene on the B. subtilis chromosome, expression of beta-galactosidase was inducible by gluconate and repressed by glucose. However, we observed no repression of beta-galactosidase activity in a strain carrying the ptsH1 mutation. Additionally, we investigated a ccpA mutant strain and observed that all of the enzymes which we found to be relieved from carbon catabolite repression in the ptsH1 mutant strain were also insensitive to catabolite repression in the ccpA mutant. Enzymes that were repressed in the ptsH1 mutant were also repressed in the ccpA mutant.
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PMID:Loss of protein kinase-catalyzed phosphorylation of HPr, a phosphocarrier protein of the phosphotransferase system, by mutation of the ptsH gene confers catabolite repression resistance to several catabolic genes of Bacillus subtilis. 819 89

The ability of the markers alpha-glucosidase, carnitine, and glycerylphosphorylcholine to indicate epididymal obstruction was studied. alpha-Glucosidase was found to be the best discriminant, with 93.4% correct classifications. The possible interrelationship between alpha-glucosidase activity, sperm ATP, and epididymal function was then studied. alpha-Glucosidase correlated positively with the percentage of motile sperm (p = 0.0212) and with the percentage of sperm with good forward progression (p = 0.0374), but correlated negatively with the sperm ATP (p < 0.0500). It was concluded that lower ATP and higher alpha-Glucosidase may be markers of efficient epididymal function. The possible epididymal origin of detached ciliary tufts (DCTs) was studied by determining ATP and alpha-glucosidase activity in patients with DCTs. The mean ATP in patients with DCTs was significantly higher (p = 0.009), but the alpha-glucosidase activity significantly lower (p = 0.0412) than in the control group. These results seem to support the epididymal origin of DCTs.
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PMID:Epididymal markers in an andrology clinic. 827 47

The bioenergetic role of the reduction of elemental sulfur (S0) in the hyperthermophilic archaeon (formerly archaebacterium) Pyrococcus furiosus was investigated with chemostat cultures with maltose as the limiting carbon source. The maximal yield coefficient was 99.8 g (dry weight) of cells (cdw) per mol of maltose in the presence of S0 but only 51.3 g (cdw) per mol of maltose if S0 was omitted. However, the corresponding maintenance coefficients were not found to be significantly different. The primary fermentation products detected were H2, CO2, and acetate, together with H2S, when S0 was also added to the growth medium. If H2S was summed with H2 to represent total reducing equivalents released during fermentation, the presence of S0 had no significant effect on the pattern of fermentation products. In addition, the presence of S0 did not significantly affect the specific activities in cell extracts of hydrogenase, sulfur reductase, alpha-glucosidase, or protease. These results suggest either that S0 reduction is an energy-conserving reaction, i.e., S0 respiration, or that S0 has a stimulatory effect on or helps overcome a process that is yield limiting. A modification of the Entner-Doudoroff glycolytic pathway has been proposed as the primary route of glucose catabolism in P. furiosus (S. Mukund and M. W. W. Adams, J. Biol. Chem. 266:14208-14216, 1991). Operation of this pathway should yield 4 mol of ATP per mol of maltose oxidized, from which one can calculate a value of 12.9 g (cdw) per mol of ATP for non-S0 growth. Comparison of this value to the yield data for growth in the presence of S0 reduction is equivalent to an ATP yield of 0.5 mol of ATP per mol of S0 reduced. Possible mechanism to account for this apparent energy conservation are discussed.
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PMID:Bioenergetics of sulfur reduction in the hyperthermophilic archaeon Pyrococcus furiosus. 844 88

Androgens in seminal plasma have been investigated in relation to other markers of the male reproductive system. Testosterone and dihydrotestosterone (DHT) were measured by radioimmunoassay after paper chromatography in 104 semen samples. Concentrations of testosterone and DHT were significantly lower in samples from patients with abnormal sperm characteristics than in men with normozoospermia. Both testosterone and DHT were correlated significantly with sperm concentration (r = 0.40, p < 0.001; r = 0.41, p < 0.001, respectively), motile sperm concentration (r = 0.35, p < 0.01; r = 0.35, p < 0.01) and ATP concentration (r = 0.59, p < 0.001; r = 0.45, p < 0.001). In addition, the total amounts of testosterone and DHT were correlated with total activity of alpha-glucosidase (r = 0.49, p < 0.001; r = 0.58, p < 0.01), and gamma-glutamyltransferase (r = 0.49, p < 0.001; r = 0.48, p < 0.001) in seminal plasma. Transferrin (Tf) concentration in seminal plasma was significantly lower in samples without spermatozoa, and total Tf content was lower in oligozoospermic samples (p < 0.05). Testosterone and DHT were correlated positively with Tf levels in seminal plasma (r = 0.48, p < 0.0001; r = 0.78, p < 0.0001 respectively). Testosterone, DHT and Tf in seminal plasma were higher in the first than in the second fraction of split ejaculates, and DHT, but not testosterone, increased significantly in each of six patients treated with tamoxifen. Testosterone, DHT, and Tf in seminal plasma were not correlated with serum concentrations of LH, FSH, testosterone or prolactin, but the DHT : T ratio in seminal plasma was correlated with serum LH (r = 0.36, p < 0.05). It is concluded that the concentration of androgens in seminal plasma is related predominantly to the activity of the seminiferous epithelium and, to a lesser extent, to the function of the accessory sex glands.
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PMID:Androgens in seminal plasma: markers of the surface epithelium of the male reproductive tract. 856 98


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