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

---

Query: EC:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The seed coat is a maternal organ which surrounds the embryo and is involved in the control of its nutrition. This study with pea (Pisum sativum L.) was conducted to understand more fully the sucrose/starch interconversions occurring in the seed coat. The concentrations of soluble sugars, the starch content, and the activities of the sucrose-metabolizing enzymes, sucrose synthase (Sus; EC 2.4.1.13), alkaline and soluble acid invertase (EC 3.2.1.26) and sucrose-phosphate synthase (SPS; EC 2.4.1.14) were compared at four developmental stages during seed filling. Among the four enzymes, only Sus activity was very high and strongly correlated with the starch concentration in the seed coat. Sucrose synthase catalyses the cleavage of sucrose in the presence of UDP into UDP-glucose and fructose. Sucrose synthase was purified from pea seed coats in a three-step protocol, consisting of diethylaminoethyl-Sephacel chromatography, gel filtration and affinity chromatography. The enzyme was characterized at the biochemical and molecular levels. Sucrose synthase exhibits biochemical properties which allow it to function in the direction of both sucrose cleavage and synthesis. The mass-action ratio of its four substrate was close to the theoretical equilibrium constant at the four developmental stages we studied. A labelling experiment on seed coats has shown that Sus activity is reversible in vivo and can produce 37% of neo-synthesized sucrose in the seed coat cells (minimum value). It is concluded that Sus could play a central role in the control of sucrose concentration in the seed coat cells in response to the demand for sucrose in the embryo during the development of the seed.
...
PMID:Purification, characterization and physiological role of sucrose synthase in the pea seed coat (Pisum sativum L.). 908 15

Fruits of cv. Fortune mandarin were periodically harvested throughout the ripening period to evaluate changes in carbohydrate content and metabolism in flavedo tissue and to determine the potential role of carbohydrates in the tolerance of citrus fruit to chilling injury (CI). Sucrose showed little change in the flavedo during the season, but fructose and glucose increased, in nearly equal amounts, throughout the fall and winter, reaching a maximum in January. Starch levels were less abundant than soluble carbohydrates and rose continuously until March. Sucrose phosphate synthase (SPS; EC 4.1.14) activity decreased from December throughout ripening. Changes in sucrose synthase (SS; EC 2.4.1.13) and acid and alkaline invertase (Inv; EC 3.2.1.26) activities correlated with changes in the reducing sugars, but acid invertase was less active than the other sucrose-metabolizing enzymes. Carbohydrate changes in the flavedo of Fortune mandarins with fruit maturity appear not to be related to the chilling tolerance of fruits during cold storage.
...
PMID:Carbohydrate content and metabolism as related to maturity and chilling sensitivity of cv. Fortune mandarins. 1055 19

This study investigated if a controlled water deficit during grain filling of wheat (Triticum aestivum L.) could accelerate grain filling by facilitating the remobilization of carbon reserves in the stem through regulating the enzymes involved in fructan and sucrose metabolism. Two high lodging-resistant wheat cultivars were grown in pots and treated with either a normal (NN) or high amount of nitrogen (HN) at heading time. Plants were either well-watered (WW) or water-stressed (WS) from 9 days post anthesis until maturity. Leaf water potentials markedly decreased at midday as a result of water stress but completely recovered by early morning. Photosynthetic rate and zeatin + zeatin riboside concentrations in the flag leaves declined faster in WS plants than in WW plants, and they decreased more slowly with HN than with NN when soil water potential was the same, indicating that the water deficit enhanced, whereas HN delayed, senescence. Water stress, both at NN and HN, facilitated the reduction in concentration of total nonstructural carbohydrates (NSC) and fructans in the stems but increased the sucrose level there, promoted the re-allocation of pre-fixed (14)C from the stems to grains, shortened the grain-filling period, and accelerated the grain-filling rate. Grain weight and grain yield were increased under the controlled water deficit when HN was applied. Fructan exohydrolase (FEH; EC 3.2.1.80) and sucrose phosphate synthase (SPS; EC 2.4.1.14) activities were substantially enhanced by water stress and positively correlated with the total NSC and fructan remobilization from the stems. Acid invertase (EC 3.2.1.26) activity was also enhanced by the water stress and associated with the change in fructan concentration, but not correlated with the total NSC remobilization and (14)C increase in the grains. Sucrose:sucrose fructosyltransferase (EC 2.4.1.99) activity was inhibited by the water stress and negatively correlated with the remobilization of carbon reserves. Sucrose synthase (EC 2.4.1.13) activity in the stems decreased sharply during grain filling and showed no significant difference between WW and WS treatments. Abscisic acid (ABA) concentration in the stem was remarkably enhanced by water stress and significantly correlated with SPS and FEH activities. Application of ABA to WW plants yielded similar results to those for WS plants. The results suggest that the increased remobilization of carbon reserves by water stress is attributable to the enhanced FEH and SPS activities in wheat stems, and that ABA plays a vital role in the regulation of the key enzymes involved in fructan and sucrose metabolism.
...
PMID:Activities of fructan- and sucrose-metabolizing enzymes in wheat stems subjected to water stress during grain filling. 1529 Feb 95

Photosynthates transported into fruits are mainly in the form of sucrose in most fruit tree species; but sorbitol takes the place of sucrose in woody Rosaceae plants. The transport of sugars across the plasma membrane from apoplastic space into cells is mediated by sugar transporters. The fact that gene expression of sugar transporters is upregulated just before and during sugar accumulation suggests the participation of sugar transporters in sugar accumulation of fruit. The sucrose-metabolizing enzymes participate in four futile cycles that involve sugar transport between cytosol, vacuole, amyloplast and apoplast. The increase in SS (sucrose synthase) and SPS (sucrose phosphate synthase) activities and mRNA levels during maturation parallels the increase in sugar accumulation indicates that the sucrose-metabolizing enzymes have important roles on sugar accumulation in fruits. The prerequisite for rapid accumulation of sugar in fruit is restriction of hexose catabolism and promotion of its synthesis. In woody Rosaceae plants, the fact that sucrose metabolism is also quite active in fruit suggests that sorbitol and sucrose probably play similar roles in fruit development. Sugars as signal molecules regulate the expression of genes involved in sugar transport and metabolism. Sugar transport, metabolism and accumulation are also regulated by natural environmental factors and cultural practices. The increase in sugar content of tomato fruit in acid invertase gene antisense-inhibited plants provides promising prospect of genetic engineering as a potential effective technique in regulation of sugar accumulation in fruits. Thus, the sugar content of fruit is determined by both intrinsic and extrinsic factors. The future research works will be focused on elucidating the mechanism of sugar signal and other intrinsic signals as well as extrinsic signals including nutrients, plant hormones and physical factors on sugar transport, metabolism and accumulation and the interrelationship among them.
...
PMID:[Sugar transport, metabolism, accumulation and their regulation in fruits]. 1558 2

Kiwifruit (Actinidia deliciosa cv. Bruno) was used to investigate starch and sugar metabolism and the mechanisms of regulation by acetylsalicylic acid (AsA 1.0 mmol/L, pH 3.5), low temperature (0 degrees C) and ethylene (100 microL/L) treatments. There was an increase in amylase activity at the initial stage followed by dramatical decrease in starch content and a rapid increase in hexose content at the rapid stage of fruit ripening and softening, which was associated with an increase in SPS activity, a decrease in acid invertase activity, and the accumulation of sucrose. AsA and low temperature treatments inhibited the amylase activity, slowed down the hydrolysis of starch and the accumulation of hexoses, suppressed the rise of SPS activity and the decline of acid invertase activity in the ripening fruit. The accumulation of sucrose was delayed by AsA and low temperature treatments. However, ethylene application induced amylase activity, accelerated starch hydrolysis, and raised the hexose content. The SPS activity also increased and the sucrose accumulated in the presence of ethylene. It is suggested that the SPS may play a key role in sugar metabolism of postharvest kiwifruit, and it could be activated by hexose and feedback-inhibited by sucrose. AsA, low temperature and ethylene treatments regulate sugar metabolism probably through influencing the SPS activity.
...
PMID:[Sugar metabolism and its regulation in postharvest ripening kiwifruit]. 1559 29

The dynamics of dry and fresh weight, the glucose, fructose, sucrose, titratable acid contents, and activities of sucrose-metabolizing and hexose-metabolizing enzymes were examined in developing fruits of bayberry (Myrica rubra Sieb. et Zucc. cvs. 'Wuzi' and 'Biqi'). The results showed the dry and fresh weight of bayberry fruit increased with fruit development and maturation (Fig. 1), with the highest increase rate of dry matters and water occurring during later stage of fruit development (about 10 d before maturation). The change in titratable acid followed a course of "low-high-low" in developing bayberry fruits (Fig. 3). The titratable acid content reached its peak at about 18 d before fruit maturation, and then decreased rapidly. The sugar compositions in fruits of bayberry cv. 'Wuzi' were different from those in fruits of bayberry cv. 'Biqi'. The main sugar accumulated in fruits of bayberry cv. 'Wuzi' was sucrose, accounting for 2/3 of total sugars but the sucrose content in fruits of bayberry cv. 'Biqi' was below 50% of total sugars. The fructose content in fruits of bayberry cv. 'Wuzi' was 4% higher, but that in fruits of bayberry cv. 'Biqi' was 12% lower than glucose content (Fig. 2). The activities of sucrose cleavage enzymes (invertase and cleavage activity of SS) in the fruit of bayberry cv. 'Biqi' increased with fruit development and maturation, but those activities in fruit bayberry cv. 'Wuzi' were almost stable during fruit development with lower levels of enzyme activities in fruit of cv. 'Wuzi' than in cv. 'Biqi' throughout fruit development (Fig. 4 and Fig. 5A). The SPS activity increased during fruit development (Fig. 6), however, the activity peak of synthetic activity of SS occurred at the middle stage of fruit development (Fig. 5B). The FRK activity in fruit of bayberry cv. 'Wuzi' was higher than that of HXK, but the reverse was in fruit of bayberry cv. 'Biqi' (Fig. 7). These results suggested that the 2-3 weeks before fruit maturation was a key phase for the bayberry development and the formation of fruit quality. There was a correlation between water transport and dry matter accumulation. The different sucrose constitutions between two varieties may be attributed to the differences in the activity levels of the sucrose cleavage enzymes while the difference in the ratio of glucose content to fructose content may be caused by the different activity levels of the hexose-metabolizing enzymes.
...
PMID:[Carbohydrate metabolism during fruit development of bayberry (Myrica rubra Sieb. et Zucc.)]. 1695 95

Green and white variegation in the Arabidopsis immutans (im) mutant is caused by a nuclear recessive gene. The green sectors contain cells with normal-appearing chloroplasts, while cells in the white sectors have photooxidized plastids lacking organized lamellae. In the present experiments, we found that the green im sectors have enhanced rates of carbon assimilation (monitored by (14)CO(2) uptake) and that there are corresponding increases in the activities of Rubisco and SPS, elevated starch and sucrose pool sizes, and an altered pattern of carbohydrate partitioning that favors sucrose over starch. We hypothesize that these increases are due, at least in part, to interactions with white sectors, perhaps to compensate for reductions in total source tissue. Consistent with this idea, the im white sectors accumulate low levels of sucrose and acid invertase activities are markedly increased in the white versus green cells. This suggests that there is a sucrose gradient between the green and white sectors, and that sucrose is transported from the green to white cells in response to sink demand. The expression of photosynthetic genes is not appreciably altered in the green im sectors versus wild type, but rather there is an up-regulation of genes involved in defense against oxidative stress and down-regulation of genes involved in cell wall biosynthesis. We postulate that changes in photosynthesis in the im green cells are driven by a need for photoprotection (especially early in chloroplast biogenesis) and due to source-sink interactions.
...
PMID:Alterations in photosynthesis in Arabidopsis lacking IMMUTANS, a chloroplast terminal oxidase. 1734 48

* Coffea arabica (Arabica) and Coffea canephora (Robusta) are the two main cultivated species used for coffee bean production. Arabica genotypes generally produce a higher coffee quality than Robusta genotypes. Understanding the genetic basis for sucrose accumulation during coffee grain maturation is an important goal because sucrose is an important coffee flavor precursor. * Nine new Coffea genes encoding sucrose metabolism enzymes have been identified: sucrose phosphate synthase (CcSPS1, CcSPS2), sucrose phosphate phosphatase (CcSP1), cytoplasmic (CaInv3) and cell wall (CcInv4) invertases and four invertase inhibitors (CcInvI1, 2, 3, 4). * Activities and mRNA abundance of the sucrose metabolism enzymes were compared at different developmental stages in Arabica and Robusta grains, characterized by different sucrose contents in mature grain. * It is concluded that Robusta accumulates less sucrose than Arabica for two reasons: Robusta has higher sucrose synthase and acid invertase activities early in grain development - the expression of CcSS1 and CcInv2 appears to be crucial at this stage and Robusta has a lower SPS activity and low CcSPS1 expression at the final stages of grain development and hence has less capacity for sucrose re-synthesis. Regulation of vacuolar invertase CcInv2 activity by invertase inhibitors CcInvI2 and/or CcInvI3 during Arabica grain development is considered.
...
PMID:Differential regulation of grain sucrose accumulation and metabolism in Coffea arabica (Arabica) and Coffea canephora (Robusta) revealed through gene expression and enzyme activity analysis. 1838 9

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

Fluxes were investigated in growing tubers from wild-type potato (Solanum tuberosum L. cv.Desiree) and from transformants expressing a yeast invertase in the cytosol under the control of the tuber-specific patatin promoter either alone (EC 3.2.1.26;U-IN2-30) or in combination with a Zymomonas mobilis glucokinase (EC 2.7.1.2; GK3-38) by supplying radiolabelled [14C]sucrose, [14C]glucose or [14C]fructose to tuber discs for a 90-min pulse and subsequent chase incubations of 4 and 12 h, and by supplying [14C]fructose for 2 h and 4 h to intact tubers attached to the mother plant. Contrary to the expectation that this novel route for sucrose degradation would promote starch synthesis,the starch content decreased in the transgenic lines.Labelling kinetics did not reveal whether this was due to changes in the fluxes into or out of starch. However,they demonstrated that glycolysis is enhanced in the transgenic lines in comparison to the wild type. There was also a significant stimulation of sucrose synthesis,leading to a rapid cycle of sucrose degradation and resynthesis. The labelling pattern indicated that sucrose phosphate synthase (SPS; EC 2.4.1.14) was responsible for the enhanced recycling of label into sucrose. In agreement, there was a 4-fold and 6-fold increase in the activation status of SPS in U-IN2-30 and GK3-38,respectively, and experiments with protein phosphatase inhibitors indicated that this activation involves enhanced dephosphorylation of SPS. It is proposed that this activation of SPS is promoted by the elevated glucose 6-phosphate levels in the transgenic tubers.These results indicate the pitfalls of metabolic engineering without a full appreciation of the metabolic system and regulatory circuits present in the tissue under investigation.
...
PMID:Tuber-specific expression of a yeast invertase and a bacterial glucokinase in potato leads to an activation of sucrose phosphate synthase and the creation of a sucrose futile cycle. 1940 52


1 2 Next >>

---