Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gastric intubation was adopted to examine the effect of continuous nutrient supply on digestive development of the pig during the immediate post-weaning period. The 14 d-weaned animals were slaughtered at 3, 5 and 7 d post-weaning (3W, 5W and 7W respectively) and the suckled animals were slaughtered at 14 and 22 d of age (14SR and 22SR respectively). The weight of the pancreas (g/kg bodyweight) was significantly greater (P less than 0.05) in the 5W and 7W groups, as was the weight of large intestine (g/kg) in all weaned groups (P less than 0.01) compared with sow-reared pigs. The stomach weight (g/kg) tended to be greater in the weaned groups. Weaning, in conjunction with a continuous nutrient supply, did not significantly alter the time-related changes in the weight of the small intestine (SI) or the SI mucosa, although both variables tended to be lowest in the 3W group. However, there was a 20% reduction in the protein content of the mucosa within the first 3 d post-weaning (P less than 0.01) which persisted during the 7 d experimental period. Lactase, (beta-galactosidase; EC 3.2.1.23) activity (mumol/g protein and mol/d) of the 7W group was reduced to approximately 40% of the 22SR value. Hence, continuous nutrient supply may have delayed, but did not prevent, the loss of lactase activity at weaning. The activity of sucrase (sucrose-alpha-glucosidase; EC 3.2.1.48) was significantly higher in 22SR compared with 14SR animals. Sucrase activity in weaned pigs was intermediate to the values for sow-reared pigs whereas maltase (alpha-glucosidase; EC 3.2.1.20) and glucoamylase (glucan 1,4-alpha-glucosidase; EC 3.2.1.3) were significantly increased in relation to their sow-reared counterparts. Continuous nutrient supply did not prevent the reduction in villous height and the crypt hypertrophy associated with weaning. The results of the present study suggest that there may be some degree of interaction between nutrient intake and gut development during the immediate post-weaning period but that there is also a component of the adaptive response which is independent of nutrient intake. They confirm the rapid substrate induction of the brush-border glucoamylases and indicate the importance of considering total as well as specific enzyme activity for satisfactory interpretation of changes in digestive function.
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PMID:Digestive development of the early-weaned pig. 1. Effect of continuous nutrient supply on the development of the digestive tract and on changes in digestive enzyme activity during the first week post-weaning. 190 70

A tetrahydroxyindolizidine alkaloid, 6,7-diepicastanospermine, was isolated from the seeds of Castanospermum australe by extraction with methanol and purified to homogeneity using ion-exchange, preparative thin-layer, and radial chromatography. A very low yield of a pyrrolidine alkaloid, N-(hydroxyethyl)-2-(hydroxymethyl)-3-hydroxypyrrolidine, was also obtained by analogous methods. The purity of both alkaloids was established by gas chromatography of their trimethylsilyl (TMS) derivatives as better than 99%. The molecular weight of each alkaloid was established as 189 and 161, respectively, by mass spectrometry, and the structure of each was deduced from their 1H and 13C NMR spectra. The structure of the pyrrolidine alkaloid is suggestive of a possible biosynthetic route to the polyhydroxyindolizidine and polyhydroxypyrrolizidine alkaloids which co-occur in C. australe. 6,7-Diepicastanospermine was found to be a moderately good inhibitor of the fungal alpha-glucosidase, amyloglucosidase (Ki = 8.4 x 10(-5) M) and a relatively weak inhibitor of beta-glucosidase. It failed to inhibit alpha- or beta-galactosidase, alpha- or beta-mannosidase, or alpha-L-fucosidase. Comparison of its inhibitory activity toward amyloglucosidase with those of its isomers, castanospermine and 6-epicastanospermine, demonstrated that epimerization of a single hydroxyl group can produce significant alteration of such inhibitory properties.
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PMID:6,7-Diepicastanospermine, a tetrahydroxyindolizidine alkaloid inhibitor of amyloglucosidase. 191 89

A new substrate, 3-ketobutylidene beta-2-chloro-4-nitrophenylmaltopentaoside (3KB-CNPG5), was used for the determination of alpha-amylase (EC 3.2.1.1) in serum and urine. Under this alpha-amylase assay condition, 3KB-CNPG5 is resistant to glucoamylase and alpha-glucosidase, which are auxiliary enzymes, because the 4- and 6-positions of the non-reducing-end glucose residue are modified by the 3-ketobutylidene group. The assay using 3KB-CNPG5 for alpha-amylase activity is a highly sensitive method that uses 2-chloro-4-nitrophenol (CNP) as an aglycone, and is a stable method for determination of alpha-amylase activity in biological fluids.
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PMID:Determination of alpha-amylase using a new blocked substrate (3-ketobutylidene beta-2-chloro-4-nitrophenyl-maltopentaoside). 193 99

1. 1-Fluoro-D-glucopyranosyl fluoride undergoes pH-independent loss of F- ion at a rate of 1 x 10(-8) s-1 at 50.0 degrees C, some 10(3)-fold slower than alpha-D-glucopyranosyl fluoride and 4 x 10(4)-fold slower than beta-D-glucopyranosyl fluoride. 2. The (inverting) amyloglucosidase II of Aspergillus niger hydrolyses the difluoride according to Michaelis-Menten kinetics (Km 34 mM and kcat. 0.27 s-1), by apparently the same (simple) mechanism by which it hydrolyses alpha-D-glucopyranosyl fluoride (Km 38 mM and kcat. 730 s-1), rather than by the Hehre resynthesis-hydrolysis mechanism used to transform beta-D-glucopyranosyl fluoride. 3. The difluoride is also a substrate for the (inverting) trehalase of pig kidney [Km 17.3 mM and Vmax. 6.2 x 10(-4) relative to alpha-D-glucopyranosyl fluoride (Km 38 mM]). 4. The quantitatively similar effect of fluorine substitution on the one-step enzymic reactions and on the non-enzymic reactions suggests that they go through similar (oxocarbonium-ion-like) transition states. 5. The difluoride is a substrate for the (retaining) beta-glucosidases from Aspergillus wentii (A3 enzyme) and sweet-almond meal (B isoenzyme) and for the retaining alpha-glucosidase from rice: comparison with the appropriate monofluoride reveals a variable rate-retarding effect of the second fluorine atom on kcat./Km that correlates with other measures of oxocarbonium ion character in the transition state. 6. The difluoride is a substrate for the (retaining) alpha-glucosidase from yeast, but also gives an insidious mimicry of active-site-directed irreversible inhibition, which we tentatively attribute either to formation of the non-covalent complex or to the fluoroglucosyl-enzyme increasing the well-known tendency of this enzyme to come out of solution by adsorption on the walls of the vessel.
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PMID:The interaction of 1-fluoro-D-glucopyranosyl fluoride with glucosidases. 195 53

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

The neutral maltase-glucoamylase complex has been purified to homogeneity from the brush-border membrane of rabbit intestine and kidney. Chemical modification of the amino acid side chains was carried out on the purified enzymes. Studies on the kidney enzyme revealed that tryptophan, histidine and cysteine were essential for both maltase and glucoamylase activities, whereas tryptophan, histidine and lysine were essential for the maltase and glucoamylase activities of the intestinal enzyme. Though there was no difference in the amino acids essential for the hydrolysis of maltose and starch by any one enzyme, starch hydrolysis seems to require two histidine residues instead of the one which is required for maltose hydrolysis. This appears to be true for both the intestinal and kidney enzymes.
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PMID:A comparison of the active site of maltase-glucoamylase from the brush border of rabbit small intestine and kidney by chemical modification studies. 200 4

Gastric intubation was adopted as a means of comparing the effect of two feeding levels, continuous nutrient supply (C) and restricted nutrient supply (R), on the digestive development of pigs weaned at 14 d of age, during the first 5 d post-weaning. The absolute weights of the stomach and the pancreas were significantly greater (P less than 0.001) in C compared with R pigs. The effect was not significant for pancreas weight when expressed per kg body-weight but was significant (P less than 0.05) for stomach weight. The weights of the small intestine (SI), SI mucosa and total mucosal protein were significantly higher (P less than 0.001) in C pigs but protein content per g mucosa was similar in the C and R groups. There was no significant effect of treatment on the activity of lactase (beta-glucosidase; EC 3.2.1.23) or sucrase (sucrose-alpha-glucosidase; EC 3.2.1.48) irrespective of the basis of comparison used. The specific activity (mumol/min per g protein) of maltase (alpha-glucosidase; EC 3.2.1.20) and of glucoamylase (glucan-1,4-alpha-glucosidase; EC 3.2.1.3) were similar in C and R groups but activities of maltase (mumol/g mucosa) (P less than 0.05), and maltase and glucoamylase (mol/d) (P less than 0.01) were significantly higher in C pigs. Villous height and crypt depth were significantly greater in C pigs (P less than 0.001 and P less than 0.05 respectively). Enteroglucagon was significantly (P less than 0.05) higher in C compared with R pigs. Xylose absorption and the digestibility of energy were not affected by treatment. Digestibility of dry matter, organic matter, crude protein (nitrogen x 6.25) and carbohydrate were significantly higher (P less than 0.001, P less than 0.01, P less than 0.05 and P less than 0.001 respectively) in R pigs compared with C pigs but the differences were small, ranging from 1.3 to 2.5%. These results demonstrate that (1) nutrient intake in the weaned pig affects the anatomy, morphology and function of the gut, (2) there is considerable 'spare capacity' for digestion of cereal-based diets even in pigs weaned at 14 d of age, (3) measurements in vitro of digestive function are of limited value unless supported by information in vivo on absorption/digestibility.
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PMID:Digestive development of the early-weaned pig. 2. Effect of level of food intake on digestive enzyme activity during the immediate post-weaning period. 204 2

Inhibition of intestinal alpha-glucohydrolase activity is one approach for reducing the glycemic response from dietary carbohydrate and may prove useful for the treatment of diabetes mellitus. In this article, we describe the pharmacological properties of a time-dependent intestinal alpha-glucohydrolase inhibitor, MDL 73945. When preincubated 2 h with a rat intestinal mucosa preparation before substrate addition, MDL 73945 was a potent inhibitor of sucrase, maltase, glucoamylase, and isomaltase activities (MDL 73945 concentrations required to cause a 50% decrease in enzyme activity, 2 x 10(-7), 1 x 10(-6), 5 x 10(-6), and 8 x 10(-6) M, respectively); without preincubation, it was 10- to 500-fold less potent. In rats, a single oral dose of MDL 73945 administered simultaneously with 2 g/kg body wt sucrose resulted in a dose-dependent reduction in the area under the 0- to 3-h glycemic response curve, which was significant at 1 (45% reduction) and 3 (65% reduction) mg/kg. When administered 1 h before sucrose, the compound was more potent, with 0.3 mg/kg MDL 73945 significantly reducing the glycemic response to sucrose by 62%. A reduction in the glycemic response to sucrose was accompanied by reduced insulin secretion. MDL 73945 was slightly less effective against a starch load, with 3 and 10 mg/kg MDL 73945 administered 0.5 h before starch reducing the glycemic response by 39 and 52%, respectively. MDL 73945 was more effective against a sucrose load in streptozocin-administered rats than in control rats and was as effective after 16 daily doses as after a single dose.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:New potent alpha-glucohydrolase inhibitor MDL 73945 with long duration of action in rats. 206 Jul 19

Initiated by the recently published histochemical method for the investigation of alfa-D-galactosidas with an indoxyl substrate, the current state of this group of synthetic compounds in light and electron microscopic histochemical glycosidase research is evaluated whereby historical, functional, methodological and applied aspects are considered. Beginning with the introduction of indoxyl acetate for non-specific esterase in 1951 and 1952 numerous other indoxyl substrates and mostly substituted in the 5- and 4-position of the indol ring by Br and Cl were developed to study histochemically non-specific phosphatases and glycosidases and frequently used in indigogenic, azoidoxyl, tetrazolium salts and metal salt techniques for catalytic (activity) histochemical and less often for immunohistochemical, affinity histochemical and hybridohistochemical purposes. The last substrate which became available and was validated for activity histochemistry was 5-Br-4-Cl-3-indoxyl alfa-1-galactoside for alfa-1-galactosidase. At present, the indoxyl glycosides are more widely used than 5-Br-4-Cl-3-indoxyl acetates and phosphates when compared with the alternative synthetic (artificial) naphthol, 6-Br-2-naphthol or ternative synthetic (artificial) naphthol, 6-Br-2-naphthol AS substrates, and among the indoxyl glycosides those for the oxoglycosidases lactase, maltase-glucoamylase, glucoamylase, acid beta-D-galactosidase, neuroaminidase and alfa-D-galactosidase are superior to other artificial compounds. When one considers in addition, electron microscopic catalytic glicosidase histochemistry (ultracytochemistry, 5-Br-4-Cl-3-indoxyl is the only suitable moiety for this purpose. These glycosidase can mostly be localized in plasma membranes or lysosomes and also measured there in tissue sections but are also found in secretion granules, endoplasmic reticulum and organ lumina.
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PMID:Indoxyl alfa-D-galactoside as the temporarily last substrate for glycosidase histochemistry. The present state of the art in histochemical glycosidase research using indoxyl glycosidas. 209 81

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


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