Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dextransucrase of Streptococcus sanguis occurred in cell-free and cell-associated forms. Cell-free dextransucrase was purified by four successive chromatographies on Bio-Gel P 60, DEAE-cellulose, and Bio-Gel P 200 from the culture supernatant. The purification of cell-associated dextransucrase was made from the pellet of Streptococcus sanguis culture. Bacterial pellet was extracted with 1 M phosphate buffer (pH 6.0) and chromatographied by using an immunosorbent column. The two enzymes gave single bands in polyacrylamide gel electrophoresis. The molecular weight determined by sodium dodecyl sulfate polyacrylamide gel was about 100 000 daltons for the two forms of dextransucrases. The optimum pH of the cell-free and cell-associated enzymes was around 6 and the temperature optimum was broad for the two enzymes. The KM values for sucrose were respectively 2 mM and 3 mM for cell-free and cell-associated enzymes. When primer dextran was added, the reaction velocity increased but the KM for sucrose remained the same, and the KA for dextran was 200 muM for the two dextransucrases. Trehalose and maltose acted also as glucosyl residue acceptors. Purified enzymes had dextran synthesising activity and invertase-like activity. The same properties of the two forms of enzymes and the positive cross reaction against anti free and anti cell-associated globulins stongly suggest the identity of the two enzymes.
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PMID:Purification and some properties of free and cell-associated dextransucrase from Streptococcus sanguis. 1 37

Addition of glucose to cells of the yeast Saccharomyces cerevisiae growing on a nonfermentable carbon source triggers a rapid, transient increase in the cAMP level. The occurrence of this cAMP spike appears to be correlated inversely with the glucose-repression state of the cells. This was also observed for the hex2 mutant, which is deficient in glucose repression and which displayed the cAMP signal constitutively. When cells of the hex2 mutant were starved for nitrogen on a glucose-containing medium, they rapidly lost viability, similarly to mutants with overactivation of the Ras-adenylate cyclase pathway. Flow cytometry measurements showed that G1 arrest of the hex2 mutant under such conditions was incomplete. Trehalose accumulation, a typical feature of cells entering the stationary phase G0, was very short-lived in the hex2 mutant under the same conditions. These results are in agreement with the presence of continuous glucose-triggered activation of cAMP synthesis in hex2 cells on a glucose-containing nitrogen-starvation medium. In the course of these experiments a spontaneous suppressor mutant, shx (for suppressor of hex2), was isolated which survived nitrogen starvation on a glucose-containing medium much better than the hex2 strain. It also showed normal G1 arrest and much longer accumulation of trehalose. The suppressor mutation also caused inability to grow on nonfermentable carbon sources and absence of invertase depression, and it was epistatic to hex2 for these characteristics also. The isolation of this epistatic depression mutation supports the idea that the defect in glucose repression of the hex2 mutant is the cause of its rapid loss of viability during nitrogen starvation on a glucose-containing medium.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Constitutive glucose-induced activation of the Ras-cAMP pathway and aberrant stationary-phase entry on a glucose-containing medium in the Saccharomyces cerevisiae glucose-repression mutant hex2. 755 Oct 24

The thermal stability of enzymes lactase and invertase in dried, amorphous matrices of sugars (trehalose, maltose, lactose, sucrose, raffinose) and some other selected systems (casein, PVP, milk) was studied. The glass transition temperature (Tg) was limited as a threshold parameter for predicting enzyme inactivation because (a) enzyme inactivation was observed in glassy matrices, (b) a specific effect of enzyme stabilization by certain matrices particularly trehalose was observed, and (c) enzyme stability appeared to depend on heating temperature (T) "per se" rather than (T-Tg). For these reasons, a protective mechanism by sugars related to the maintenance of the tertiary structure of the enzyme was favored. A rapid loss of enzyme (lactase) activity was observed in heated sucrose systems at T > Tg, and this was attributed to sucrose crystallization since it is known that upon crystallization the protective effect of sugars is lost. Thus, the stabilizing effect could be indirectly affected by the Tg of the matrix, since crystallization of sugars only occurs above Tg. Trehalose model systems (with added invertase) showed an exceptional stability toward "darkening" (e.g., non-enzymatic browning) when heated in the dried state to elevated temperatures and for long periods of time.
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PMID:Glassy state and thermal inactivation of invertase and lactase in dried amorphous matrices. 941 44

The response to moderate salt stress of a Scytonema species isolated from a soil crust in the arid region of central Australia was studied. An increase in intracellular trehalose and sucrose concentrations was detected by NMR and HPLC analysis following salt stress, maximal amounts being produced by exposure to 150 mM NaCl after 48 h. When the organism was subsequently returned to normal growth conditions, the cellular concentrations of these solutes decreased. The biosynthesis of trehalose and sucrose was studied and found, in both cases, to involve both sugar phosphate synthase and phosphatase enzymes. The combined synthase activities and the individual phosphatase activities in cell extracts were increased by salt stress. Trehalose phosphorylase was the only catabolic enzyme detected for trehalose; neither trehalase nor phosphotrehalase activities could be detected. This is the first report of trehalose phosphorylase activity in cyanobacteria. Both trehalose and sucrose phosphorylase activities increased in salt-stressed cells, whereas the activity of invertase did not change.
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PMID:Involvement of the compatible solutes trehalose and sucrose in the response to salt stress of a cyanobacterial Scytonema species isolated from desert soils. 1056 66

Trehalose is a disaccharide, the main dietary source being mushrooms. It has been approved as an additive in the preparation of dried food. Isolated intestinal trehalase deficiency is found in 8% of Greenlanders, but is rare elsewhere. The normal range of trehalase activity and the incidence of isolated trehalase deficiency in the UK have not been reported. Patients (n 400) were investigated for suspected malabsorption. Endoscopic distal duodenal biopsies were taken for histological assessment and maltase, sucrase, lactase and trehalase estimation. Disaccharidase activities were determined by Dahlqvist's technique (Dahlqvist, 1968). Most patients (n 369) had normal duodenal histology. In these, square root transformation of trehalase activity produced a normal distribution. The normal range (mean +/- 2 SD) was 4.79-37.12 U/g protein. One patient had an isolated borderline trehalase deficiency. The thirty-one patients with villous atrophy had significantly reduced disaccharidase activities. With ingestion of a gluten-free diet, maltase, sucrase and trehalase activities recovered to normal in most patients, whereas lactase activity did not. The normal range and very low incidence of isolated enzyme deficiency is comparable with that described in populations from the USA and mainland Europe. Activity is significantly reduced in untreated coeliac disease and recovers with treatment with a gluten-free diet. There is no place for routine determination of trehalase activity in the UK population and there should be no concern over the introduction of trehalose-containing dried foods.
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PMID:Intestinal trehalase activity in a UK population: establishing a normal range and the effect of disease. 1088 12

Trehalose, an alpha,alpha-diglucoside, induced a rapid blackening and death of shoot tips of Cuscuta reflexa (dodder) cultured in vitro. The onset of toxic symptom was delayed if any of the several sugars which support the in vitro growth of Cuscuta was supplied with trehalose. The rate of trehalose uptake or its accumulation in the tissue was not affected by sugar cofeeding. The levels of total and reducing sugars declined appreciably in the trehalose-fed shoot tip explants compared to control tissue cultured in absence of a carbon source. This was not due to an increased rate of respiration of the trehalose-treated tissue. In shoot tips cultured in presence of both trehalose and sucrose, the decline in total and reducing sugars was curtailed. There was a marked fall in the level of sucrose; and invertase activity was higher in trehalose-fed shoot tips. The incorporation of label from [(14)C]glucose into sucrose in the shoot tip explant was reduced as early as 12 h of trehalose feeding. The results suggest that increased utilization of sucrose as well as an inhibition of its synthesis contribute to the drastic fall in the sucrose content upon trehalose feeding.
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PMID:Trehalose Toxicity in Cuscuta reflexa: SUCROSE CONTENT DECREASES IN SHOOT TIPS UPON TREHALOSE FEEDING. 1666 80

Excised primary leaf blades of barley (Hordeum vulgare L. cv Gerbel) rapidly synthesized large quantities of fructan in the light and, upon transfer to the dark, they rapidly degraded it again. In the course of such a light/dark cycle the activities of sucrose-sucrose-fructosyltransferase (SST), fructan hydrolase, and invertase were measured in cell-free extracts of the blades. SST activity increased 20-fold within 24 hours in the light and disappeared again upon transfer to the dark during a similar period of time. Cycloheximide inhibited the increase of SST activity in the light indicating de novo synthesis. The loss of SST activity in the dark, however, was unaffected by cycloheximide. No SST activity appeared in the light if photosynthesis was inhibited by lowering the CO(2) concentration in the atmosphere. However, SST activity and fructan synthesis were induced even in the dark and at a low CO(2) concentration when the leaf blades were immersed in a solution of sucrose. Several other sugars, maltose and fructose in particular, had the same effect. Trehalose induced SST activity but no fructan synthesis occurred. The activities of fructan hydrolase and invertase changed little during the light/dark cycle. It is suggested that the control of SST activity in conjunction with the supply of photosynthates plays a key role in the regulation of fructan metabolism.
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PMID:Regulation of Fructan Metabolism in Leaves of Barley (Hordeum vulgare L. cv Gerbel). 1666 35

In this work, the role of trehalose as an osmoprotectant against salt stress conditions was examined in root nodules of Medicago truncatula. For this purpose, we used validamycin A, a potent trehalase inhibitor, in order to induce trehalose accumulation. Validamycin A induced an increase of trehalose concentration in root nodules of M. truncatula by inhibiting trehalase activity; no effect on trehalose concentration was observed in roots and leaves. Trehalose accumulation was accompanied by a decrease in sucrose and starch content, indicating interference with carbohydrate partitioning in the plants. Under salinity conditions, sucrose accumulation appears to be induced in M. truncatula to protect nodule functioning by the inhibition of sucrose catabolism by sucrose synthase and alkaline invertase activities. However, trehalose accumulation induced by val A in nodules improved the response to salinity by increasing plant dry weight (PDW), and no effects of validamycin A on nitrogenase activity and PDW were observed in nonsalinized plants.
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PMID:Validamycin A improves the response of Medicago truncatula plants to salt stress by inducing trehalose accumulation in the root nodules. 1923 73

Trehalose and sucrose, two important anti-stress non-reducing natural disaccharides, are catabolized by two enzymes, namely trehalase and invertase respectively. In this study, a 175 kDa enzyme protein active against both substrates was purified from wild type Candida utilis and characterized in detail. Substrate specificity assay and activity staining revealed the enzyme to be specific for both sucrose and trehalose. The ratio between trehalase and invertase activity was found to be constant at 1:3.5 throughout the entire study. Almost 40-fold purification and 30% yield for both activities were achieved at the final step of purification. The presence of common enzyme inhibitors, thermal and pH stress had analogous effects on its trehalase and invertase activity. Km values for two activities were similar while Vmax and Kcat also differed by a factor of 3.5. Competition plot for both substrates revealed the two activities to be occurring at the single active site. N-terminal sequencing and MALDI-TOF data analysis revealed higher similarity of the purified protein to previously known neutral trehalases. While earlier workers mentioned independent purification of neutral trehalase or invertase from different sources, the present study reports the purification of a single protein showing dual activity.
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PMID:Purification and characterization of a trehalase-invertase enzyme with dual activity from Candida utilis. 2248 63