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

Two different forms of invertase are found in pollen of lily (Lilium auratum). One form is cytoplasmic (Invertase 1) and the other is bound to the pollen wall (Invertase 2). Invertase 1 has been partially purified and is a glycoprotein (apparent molecular weight, 450 kilodaltons) with a K(m) of 0.65 millimolar for sucrose. The two invertases differ in pH optimum and thermal stability. Invertases of lily pollen are beta-fructofuranosidases which can hydrolyze sucrose but not melizitose. The mature pollen grains have enzyme activity in both cytoplasmic and wall fractions, and no increase in the activity of either occurs during germination. The wall-bound enzyme could not be released by treatments with detergents or high salt concentrations.
 ...
PMID:Invertases of Lilium Pollen : Characterization and Activity during In Vitro Germination. 1666 53

Barley (Hordeum vulgare L.) is a salt-tolerant member of the Triticeae. Recent transcriptome studies on salinity stress response in barley revealed regulation of jasmonic acid (JA) biosynthesis and JA-responsive genes by salt stress. From that observation and several other physiological reports, it was hypothesized that JA is involved in the adaptation of barley to salt stress. Here we tested that hypothesis by applying JA to barley plants and observing the physiological responses and transcriptome changes. Photosynthetic and sodium ion accumulation responses were compared after (1) salinity stress, (2) JA treatment and (3) JA pre-treatment followed by salinity stress. The JA-pre-treated salt-stressed plants accumulated strikingly low levels of Na(+) in the shoot tissue compared with untreated salt-stressed plants after several days of exposure to stress. In addition, pre-treatment with JA partially alleviated photosynthetic inhibition caused by salinity stress. Expression profiling after a short-term exposure to salinity stress indicated a considerable overlap between genes regulated by salinity stress and JA application. Three JA-regulated genes, arginine decarboxylase, ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco) activase and apoplastic invertase are possibly involved in salinity tolerance mediated by JA. This work provides a reference data set for further study of the role of JA in salinity tolerance in barley and other plants species.
 ...
PMID:Large-scale expression profiling and physiological characterization of jasmonic acid-mediated adaptation of barley to salinity stress. 1732 28

A salt-sensitive genotype of Solanum lycopersicum cv. Volgogradskij was submitted to a 6-day treatment with high salt (100, 200 mM NaCl), allowed to recover for 6 days and then submitted to a second period of salt stress in order to study changes in carbohydrate metabolism related to salt adaptation. The ion, soluble sugar and starch contents, as well as sucrose biosynthetic and sugar mobilizing enzyme activities and transcript levels were determined during the salt stress/recovery/stress cycle. Sodium ions were found to accumulate preferentially in old leaves. Young leaves accumulated lower levels of sodium ions but maintained control levels of potassium ions. Hexoses accumulated to higher levels and starch was better maintained in young compared to old leaves during the two salt treatments. Sucrose accumulated dramatically only in old leaves during the initial salt treatment. Sugar accumulation was not related to decreases in the activities of sugar mobilizing enzymes, acid (EC 3.2.1.25) and neutral (EC 3.2.1.26) invertases, sucrose synthase (EC 2.4.1.13) and hexokinase (EC 2.7.1.1). The activity of the biosynthetic enzyme sucrose phosphate synthase (EC 2.3.1.14) was linked to changes in sucrose levels but not with transcript levels. These results point to the importance of post-transcriptional regulation. Transcriptional regulation could nevertheless be seen in the down-regulation of ribulose bisphosphate carboxylase small subunit (EC 4.1.1.39) in old compared to young leaves, but this was not related to sugar levels.
 ...
PMID:Adaptive response to salt involving carbohydrate metabolism in leaves of a salt-sensitive tomato cultivar. 1762 95

Lotus japonicus and Medicago truncatula model legumes, which form determined and indeterminate nodules, respectively, provide a convenient system to study plant-Rhizobium interaction and to establish differences between the two types of nodules under salt stress conditions. We examined the effects of 25 and 50mM NaCl doses on growth and nitrogen fixation parameters, as well as carbohydrate content and carbon metabolism of M. truncatula and L. japonicus nodules. The leghemoglobin (Lb) content and nitrogen fixation rate (NFR) were approximately 10.0 and 2.0 times higher, respectively, in nodules of L. japonicus when compared with M. truncatula. Plant growth parameters and nitrogenase activity decreased with NaCl treatments in both legumes. Sucrose was the predominant sugar quantified in nodules of both legumes, showing a decrease in concentration in response to salt stress. The content of trehalose was low (less than 2.5% of total soluble sugars (TSS)) to act as an osmolyte in nodules, despite its concentration being increased under saline conditions. Nodule enzyme activities of trehalose-6-phosphate synthase (TPS) and trehalase (TRE) decreased with salinity. L. japonicus nodule carbon metabolism proved to be less sensitive to salinity than in M. truncatula, as enzymatic activities responsible for the carbon supply to the bacteroids to fuel nitrogen fixation, such as sucrose synthase (SS), alkaline invertase (AI), malate dehydrogenase (MDH) and phosphoenolpyruvate carboxylase (PEPC), were less affected by salt than the corresponding activities in barrel medics. However, nitrogenase activity was only inhibited by salinity in L. japonicus nodules.
 ...
PMID:Growth and nitrogen fixation in Lotus japonicus and Medicago truncatula under NaCl stress: nodule carbon metabolism. 1772 11

In Arabidopsis thaliana, six vacuolar Na(+)/H(+) antiporters (AtNHX1-6) were identified. Among them, AtNHX1, 2 and 5 are functional Na(+)/H(+) antiporters with the most abundant expression levels in seedling shoots and roots. However, the expression of AtNHX3 in Arabidopsis can only be detected by RT-PCR, and its physiological function still remains unclear. In this work, we demonstrate that constitutive expression of AtNHX3 in sugar beet (Beta vulgaris L.) conferred augmented resistance to high salinity on transgenic plants. In the presence of 300 or 500 mm NaCl, transgenic plants showed very high potassium accumulation in the roots and storage roots. Furthermore, the transcripts of sucrose phosphate synthase (SPS), sucrose synthase (SS) and cell wall sucrose invertase (SI) genes were maintained in transgenic plants. The accumulation of soluble sugar in the storage roots of transgenic plants grown under high salt stress condition was also higher. Our results implicate that AtNHX3 is also a functional antiporter responsible for salt tolerance by mediating K(+)/H(+) exchange in higher plants. The salt accumulation in leaves but not in the storage roots, and the increased yield of storage roots with enhanced constituent soluble sugar contents under salt stress condition demonstrate a great potential use of this gene in improving the quality and yield of crop plants.
 ...
PMID:Transgenic salt-tolerant sugar beet (Beta vulgaris L.) constitutively expressing an Arabidopsis thaliana vacuolar Na/H antiporter gene, AtNHX3, accumulates more soluble sugar but less salt in storage roots. 1851 17

A spectrophotometric method for determining sucrose is proposed. Sucrose is hydrolyzed by invertase into glucose and fructose. Then, glucose is oxidized in presence of glucose oxidase and the produced hydrogen peroxide reacts with phenol-4-sulfonic acid sodium salt and 4-aminoantipyrine in presence of peroxidase, yielding a pink dye with an absorption maximum at 505 nm. This method was validated following the EURACHEM and VAM project guidelines for method validation. Trueness, precision, robustness, sensitivity and linearity were considered. The method was applied to the determination of sucrose in green and roasted coffee beans. A comparison with the HPLC method with pulsed amperometric detection was carried out.
 ...
PMID:Enzymatic-spectrophotometric determination of sucrose in coffee beans. 1897 Feb 37

We report for the first time kinetic and thermodynamic properties of soluble acid invertase (SAI) of sugarcane (Saccharum officinarum L.) salt sensitive local cultivar CP 77-400 (CP-77). The SAI was purified to apparent homogeneity on FPLC system. The crude enzyme was about 13 fold purified and recovery of SAI was 35%. The invertase was monomeric in nature and its native molecular mass on gel filtration and subunit mass on SDS-PAGE was 28 kDa. SAI was highly acidic having an optimum pH lower than 2. The acidic limb was missing. Proton transfer (donation and receiving) during catalysis was controlled by the basic limb having a pKa of 2.4. Carboxyl groups were involved in proton transfer during catalysis. The kinetic constants for sucrose hydrolysis by SAI were determined to be: k(m)=55 mg ml(-1), k(cat)=21s(-1), k(cat)/k(m)=0.38, while the thermodynamic parameters were: DeltaH*=52.6 kJ mol(-1), DeltaG*=71.2 kJ mol(-1), DeltaS*=-57 J mol(-1) K(-1), DeltaG*(E-S)=10.8 kJ mol(-1) and DeltaG*(E-T)=2.6 kJ mol(-1). The kinetics and thermodynamics of irreversible thermal denaturation at various temperatures 53-63 degrees C were also determined. The half -life of SAI at 53 and 63 degrees C was 112 and 10 min, respectively. At 55 degrees C, surprisingly the half -life increased to twice that at 53 degrees C. DeltaG*, DeltaH* and DeltaS* of irreversible thermal stability of SAI at 55 degrees C were 107.7 kJ mol(-1), 276.04 kJ mol(-1) and 513 J mol(-1) K(-1), respectively.
 ...
PMID:Purification, kinetic and thermodynamic characterization of soluble acid invertase from sugarcane (Saccharum officinarum L.). 1909 83

The effect of low temperature on growth, sucrose-starch partitioning and related enzymes in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) was studied. The growth of cotyledons and growing axes in seedlings grown at 25/20 degrees C (light/dark) and shifted to 5/5 degrees C was lower than in those only growing at 25/20 degrees C (unstressed). However, there were no significant differences between low-temperature control and salt-treated seedlings. The higher activities of sucrose phosphate synthase (SPS, EC 2.4.1.14) and soluble acid invertase (acid INV, EC 3.2.1.25) were observed in salt-stressed cotyledons; however, the highest acid INV activity was observed in unstressed cotyledons. ADP-glucose pyrophosphorylase (ADP-GPPase, EC 2.7.7.27) was higher in unstressed cotyledons than in stressed ones. However, between 0 and 4days the highest value was observed in salt-stressed cotyledons. The lowest value of ADP-GPPase was observed in salt-acclimated cotyledons. Low temperature also affected sucrose synthase (SuSy, EC 2.4.1.13) activity in salt-treated cotyledons. Sucrose and glucose were higher in salt-stressed cotyledons, but fructose was essentially higher in low-temperature control. Starch was higher in low-temperature control; however, the highest content was observed at 0day in salt-acclimated cotyledons. Results demonstrated that low temperature induces different responses on sucrose-starch partitioning in salt-stressed and salt-acclimated cotyledons. Data also suggest that in salt-treated cotyledons source-sink relations (SSR) are changed in order to supply soluble sugars and proline for the osmotic adjustment. Relationships between starch formation and SuSy activity are also discussed.
 ...
PMID:Low-temperature effect on enzyme activities involved in sucrose-starch partitioning in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) seedlings. 1912 55

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.
 ...
PMID:Validamycin A improves the response of Medicago truncatula plants to salt stress by inducing trehalose accumulation in the root nodules. 1923 73

Intestinal brush border sucrase-isomaltase (sucrose D-glucosidase E.C. 3.2.1.48, E.C. 3.2.1.10) exhibits pH-dependent stimulatory or inhibitory effects in response to Na+ ions. However, whether the enzyme undergoes conformational modulations as a function of pH and in the presence of alkali metal ions is not known. In this paper, we investigated the structural and functional relationship of purified murine sucrase in response to pH and Na+ ions using UV-CD fluorescence and spectroscopic studies. Kinetic studies revealed that at pH 5.0, the enzyme activation by Na+ ions was V-type, which changed to K-type at pH 7.2, whereas at alkaline pH (8.5), Na+ ions inhibited the enzyme activity and inhibition was uncompetitive in nature, affecting both the Km and Vmax components. Far UV-CD spectra of protein at pH 7.2 in the absence and presence of Na+ were almost overlapping, suggesting that secondary structure of protein was not affected upon addition of the salt. However, near UV-CD spectra indicated marked alterations in the tertiary structure of protein in presence of 50 mM Na+ ions. Increase in pH from 7.2 to 8.5 resulted in a marked rise in fluorescence intensity and red shift in lambda max due to tryptophan residues in the enzyme molecule. These findings suggested that alterations in enzyme activity as a function of pH and Na+ ions was associated with ionization of key amino acid residues together with structural modifications in the enzyme conformation around neutral or alkaline pH.
 ...
PMID:Effect of Na+ ions on pH-dependent conformational changes in brush border sucrase-isomaltase in mice intestine. 1923 26


<< Previous 1 2 3 4 5 6 7 8 9 Next >>