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)

Glycogen can be degraded in mammalian tissues by one of three isozymes of glycogen phosphorylase, termed muscle (M), liver (L) and brain (B) after the tissues in which they are preferentially expressed in adult animals, or by members of the family of alpha-glucosidases. In the current study, we have examined the developmental expression of these enzymes and their respective mRNAs in rabbit tissues, with particular emphasis on the developing lung, a tissue in which glycogen serves as an important source of carbon for surfactant phospholipid biosynthesis. Native gel activity assays and RNA blot hybridization analysis revealed that the B isoform of glycogen phosphorylase predominates in fetal and adult lung tissues, accompanied by a low level of expression of the M isoform. Total B and M phosphorylase activities increased during fetal lung development, with a peak at day 28 of gestation, then decreased to the adult level at term. This peak in activity coincided with the peak period of glycogen degradation in developing lung. While the increase in M isozyme activity was correlated with an increase in the level of its mRNA, B isoform mRNA showed no significant alteration during development, suggesting that the increase in B isoform activity is determined by a posttranscriptional mechanism. Analysis of phosphorylase mRNA levels in developing liver, skeletal muscle, brain and heart revealed a diverse expression pattern. The L isozyme mRNA was predominant at all time points in liver, the M isozyme was predominant at all time points in muscle, the B isozyme was predominant at all time points in brain, and heart contained a mixture of B and M mRNA in roughly equal ratios at all time points. Thus, our studies of phosphorylase mRNA in the rabbit provide no evidence for general predominance of the B isozyme in fetal tissues, or for isozyme 'switching' from the B to the L or M forms during development, as has been suggested by others. In addition to the increase in phosphorylase activity, acid, but not neutral alpha-glucosidase activity was found to increase significantly during fetal lung development, again with a peak at day 28 of gestation. Interestingly, RNA blot hybridization analysis with a probe for lysosomal alpha-glucosidase revealed no change in the level of expression of its 4 kb transcript in developing lung. Instead, we observed induction of a structurally related mRNA of 7.4 kb that peaked at day 28 of gestation. Hybridization with a sucrase/isomaltase-specific oligonucleotide excluded the possibility that the 7.4 kb transcript encodes this protein.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Developmental expression of glycogenolytic enzymes in rabbit tissues: possible relationship to fetal lung maturation. 195 55

Rats trained on a diurnal controlled meal-feeding schedule and injected with a single dose of 3,5,3'-triiodothyronine (T3) failed to accumulate liver glycogen and incorporated less D-[6-3H]glucose into glycogen than normally observed during the feeding period. In the experimental group, the concentration of liver adenosine 3',5'-cyclic monophosphate (cAMP) did not fall during feeding and the pattern of activities of glycogen phosphorylase, glycogen synthase, and phosphorylase kinase remained conductive to glycogenolysis. Liver lysosomal alpha-glucosidase activity normally fell during feeding periods. After T3 treatment the activities of alpha-glucosidase and two lysosomal cathepsins (B1 and D) were elevated. The evidence suggests that T3 may induce both liver phosphorylase kinase and lysosomal alpha-glucosidase. This outcome of T3 excess, in concert with previously described T3-inducible systems, provides a plausible explanation for the failure of glycogen accumulation in this experimental model.
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PMID:Mechanisms underlying enhanced glycogenolysis in livers of 3,5,3'-triiodothyronine-treated rats. 210 55

1. Glycogen, glucose, lactate and glycogen phosphorylase concentrations and the activities of glycogen phosphorylase a and acid 1,4-alpha-glucosidase were measured at various times up to 120 min after death in the liver and skeletal muscle of Wistar and gsd/gsd (phosphorylase b kinase deficient) rats and Wistar rats treated with the acid alpha-glucosidase inhibitor acarbose. 2. In all tissues glycogen was degraded rapidly and was accompanied by an increase in tissue glucose and lactate concentrations and a lowering of tissue pH. In the liver of Wistar and acarbose-treated Wistar rats and in the skeletal muscle of all rats glycogen loss proceeded initially very rapidly before slowing. In the gsd/gsd rat liver glycogenolysis proceeded at a linear rate throughout the incubation period. Over 120 min 60, 20 and 50% of the hepatic glycogen store was degraded in the livers of Wistar, gsd/gsd and acarbose-treated Wistar rats, respectively. All 3 types of rat degraded skeletal muscle glycogen at the same rate and to the same extent (82% degraded over 2 hr). 3. In Wistar rat liver and skeletal muscle glycogen phosphorylase was activated soon after death and the activity of phosphorylase a remained well above the zero-time level at all later time points, even when the rate of glycogenolysis had slowed significantly. Liver and skeletal muscle acid alpha-glucosidase activities were unchanged after death. 4. The decreased rate and extent of hepatic glycogenolysis in both the gsd/gsd and acarbose-treated rats suggests that this process is a combination of phosphorolysis and hydrolysis. 5. Glycogen was purified from Wistar liver and skeletal muscle at various times post mortem and its structure investigated. Fine structural analysis revealed progressive shortening of the outer chains of the glycogen from both tissues, indicative of random, lysosomal hydrolysis. Analysis of molecular weight distributions showed inhomogeneity in the glycogen loss; in both tissues high molecular weight glycogen was preferentially degraded. This material is concentrated in lysosomes of both skeletal muscle and liver. These results are consistent with a role for lysosomal hydrolysis in glycogen degradation.
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PMID:Post mortem glycogenolysis is a combination of phosphorolysis and hydrolysis. 227 18

The changes in the activities of three important glycogen metabolising enzymes, viz. glycogen synthetase, glycogen phosphorylase and alpha-D-glucosidase, along with glycogen content have been measured in adult human heart and human fetal heart collected at 13-36 weeks of gestation. At an early period, particularly 13-16 weeks of gestational age, the activity of glycogen synthetase and glycogen content were found to be maximum. However the activity of glycogen phosphorylase remained constant throughout the gestation and that of alpha-D-glucosidase showed a peak at 25-28 weeks of gestation, thereby indicating that fetal heart tissue has the capacity to utilise glycogen for energy.
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PMID:Age-related changes of glycogen metabolism in human fetal heart. 277 20

Freshwater turtles Trachemys scripta elegans endure prolonged severe hypoxia, and even complete anoxia, while diving or hibernating underwater. Metabolic adaptations supporting survival include the activation of glycogenolysis and glucose output from liver, as well as strong metabolic rate depression. The present study analyzes the enzymes of both the phosphorolytic (glycogen phosphorylase, phosphorylase b kinase, cAMP-dependent protein kinase) and glucosidic (alpha-glucosidase) pathways of glycogenolysis in turtle organs. Turtles were subjected to 5 hr of submergence in N2-bubbled water at 7 degrees C and then activities of phosphorolytic and glucosidic enzymes were assayed in liver, heart, brain, and red and white skeletal muscle, and compared with aerobic controls. In vitro incubations also assessed protein kinase A control of phosphorolytic enzymes. A functional enzyme cascade system for the activation of glycogen phosphorylase was found in all organs, and both phosphorylase and phosphorylase kinase were stimulated by in vitro incubation with the catalytic subunit of cAMP-dependent protein kinase. Anoxic submergence led to significant increases in phosphorylase activities in liver and heart (phosphorylase a rose 2- and 2.5-fold, respectively) but phosphorylase kinase and protein kinase A activities in liver were reduced after 5 hr exposure. Both acidic (pH 4) and neutral (pH 7) forms of alpha-glucosidase were detected in all five organs with highest activities in liver. Activity of acid alpha-glucosidase, which degrades lysosomal glycogen, increased by 2-fold in liver during anoxic submergence. The data show that glycogen breakdown in turtle liver during anoxic submergence may result from coordinated activations of both the cytoplasmic phosphorolytic and the lysosomal glucosidic pathways of glycogenolysis.
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PMID:Enzymatic control of glycogenolysis during anoxic submergence in the freshwater turtle Trachemys scripta. 758 17

The glycogenolysis markers (glycogen content, active and total glycogen phosphorylase [EC 2.4.1.1.] activities, and active and total acid exo-alpha-1,4-glucosidase [EC 3.2.1.3.] activities) in the urinary bladder muscle from two patients with stress urinary incontinence and concomitant detrusor instability were studied. Glycogen depletion and activation of glycogen phosphorylase were found.
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PMID:Stress urinary incontinence in women. III. Different tissue biochemistry in patients with concomitant detrusor instability. Preliminary report. 969 33

A combinatorial library of 125 compounds with a structure consisting of 1-azafagomine linked at N-1 via an acetic acid linker to a variable tripeptide was synthesised. The library was synthesised by Merrifield split and mix synthesis of the peptide, followed by capping with chloroacetate, regioselective nucleophilic substitution with 1-azafagomine and cleavage from the polymeric support. The library was screened for inhibition of beta-glucosidase, alpha-glucosidase and glycogen phosphorylase and found to display beta-glucosidase inhibition. Deconvolution of the library revealed that some inhibition was caused by all library members but the strongest inhibitor was clearly a compound having three hydroxyproline residues in the peptide fragment. This compound was a weaker but more selective inhibitor than 1-azafagomine itself.
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PMID:Synthesis and deconvolution of the first combinatorial library of glycosidase inhibitors. 1053 Sep 45

The activity of alpha-amylase, glucoamylase, maltase, trehalase, glycogen phosphorylase and trehalose phosphorylase was measured in extracts from larval and adult Hysterothylacium aduncum (Rudolphi, 1802), parasitic nematode of marine fish. The content of glycogen and trehalose in the worm's body was also determined. Both the hydrolytic and phosphorolytic paths of sugar decomposition are present in H. aduncum. In the larvae glycogen was utilised mainly via the hydrolytic path. In the adults the activities of phosphorolytic enzymes were higher than in the larvae. In both stages the activity of trehalose phosphorylase is present. In adult nematodes it is uncommonly high. The dominating sugars in the adults were glucose and glycogen, while in the larvae it was trehalose.
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PMID:The enzymes of glycogen and trehalose catabolism from Hysterothylacium aduncum (Nematoda: Anisakidae). 1241 18

The content of glycogen, glucose and trehalose was measured in larvae and adults of Cystidicola farionis, the parasite isolated from the swim bladder of Osmerus eperlanus from Vistula Lagoon. Activity of glycogen phosphorylase, alpha-amylase, glucoamylase, maltase, trehalase, and trehalose phosphorylase were measured. The highest activity was recorded for alpha-amylase 10.07 +/- 0.97 mu/mg and 7.47 +/- 0.24 mu/mg, next maltase 1.34 +/- 0.63 micromol/mg and 2.06 +/- 1.65 micronol/mg respectively for larvae and adults. The activity of glucoamylase was nearly the same for adults and larvae (about 0.20 micromol/mg). The trehalase activity was higher at adults (0.49 +/- 0.42 micromol/mg) than at larvae (0.18 +/- 0.12 micromol/mg). The activity of glycogen phosphorylase was much higher at larvae (3.58 +/- 1.49 micromol/mg) than at adults parasite (0.10 +/- 0.02 micromol/mg). The trehalose phosphorylase was present in both stages of parasite, but its activity was low. The content of glycogen and glucose was two-times higher in the adults' body than in larvae.
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PMID:[The enzymes of carbohydrates metabolism from Cysttidicola farionis (Cystidicolidae)]. 1689 40

We investigated inhibitory activities of five-membered sugar mimics toward glycogen-degrading enzymes and a variety of glucosidases. 1,4-Dideoxy-1,4-imino-D-arabinitol (D-AB1) is known to be a potent inhibitor of glycogen phosphorylase. However, the structural modification of D-AB1, such as its enantiomerization, epimerization at C-2 and/or C-3, introduction of a substituent to C-1, and replacement of the ring nitrogen by sulfur, markedly lowered or abolished its inhibition toward the enzyme. The present work elucidated that d-AB1 was also a good inhibitor of the de-branching enzyme of glycogen, amylo-1,6-glucosidase, with a IC(50) value of 8.4 microM. In the present work, the de-sulfonated derivative of salacinol was isolated from the roots of Salacia oblonga and found to be a potent inhibitor of rat intestinal isomaltase with an IC(50) value of 0.64 microM. On the other hand, salacinol showed a much more potent inhibitory activity toward maltase in Caco-2 cell model system than its de-sulfonated derivative, with an IC(50) value of 0.5 microM, and was further a stronger inhibitor of human lysosomal alpha-glucosidase than the derivative (IC(50)=0.34 microM). This indicates that the sulfate in the side chain plays an important role in the specificity of enzyme inhibition.
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PMID:Effect of five-membered sugar mimics on mammalian glycogen-degrading enzymes and various glucosidases. 1825 41


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