Regulation Of Fructose Research Articles

Exogenously applied zinc improves sugar-acid profile of loquat (Eriobotrya japonica Lindl.) by regulating enzymatic activities and expression of their metabolism-related genes

Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. In this study, loquat trees were sprayed with 0.1, 0.2 and 0.3% zinc sulphate. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of key enzymes involved in sugar-acid metabolism were measured and expression profiling of related genes was done using RT-qPCR. The results revealed that 0.1% zinc sulphate was a promising treatment among other Zn applications with respect to the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While, the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, EjSPS1-4, EjSS2-4, EjHK1-3, and EjFK1-6 may play an important role in soluble sugar metabolism in the pulp of loquat fruits. Similarly, EjPEPC2, EjPEPC3, EjNAD-MDH1, EjNAD-MDH3-5, EjNAD-MDH6 and EjNAD-MDH13 may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.

One step purification and regulation of fructose 1,6-bisphosphatase from liver of the freeze tolerant wood frog, Rana sylvatica

One step purification and regulation of fructose 1,6-bisphosphatase from liver of the freeze tolerant wood frog, Rana sylvatica

Sugar and acid profile of loquat (Eriobotrya japonica Lindl.), enzymes assay and expression profiling of their metabolism-related genes as influenced by exogenously applied boron.

Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. Some loquat cultivars have high acid content which seriously affect the quality of fruit and reduce the value of commodity. Consequently, studying the physiological mechanism of sugar-acid metabolism in loquat can clarify the mechanism of their formation, accumulation and degradation in the fruit. Minerals application has been reported as a promising way to improve sugar-acid balance of the fruits. In this study, loquat trees were foliar sprayed with 0.1, 0.2 and 0.3% borax, and changes in soluble sugars and organic acids were recorded. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of enzymes responsible forthe metabolism of sugarsand acids were quantified and expressions of related genes were determined using quantitative real-time PCR. The results revealed that 0.2% borax was a promising treatment among other B applications for the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, EjSPS1, EjSPS3, EjSS3, EjHK1, EjHK3, EjFK1, EjFK2, EjFK5, and EjFK6 may play an important role in soluble sugars metabolism in fruit pulp of loquat. Similarly, EjPEPC2, EjPEPC3, EjNAD-ME1, EjNAD-MDH1, EjNAD-MDH5-8, EjNAD-MDH10, and EjNAD-MDH13 may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.

One-step purification and regulation of fructose 1,6-bisphosphatase from the liver of the freeze-tolerant wood frog, Rana sylvatica.

The wood frog (Rana sylvatica) undergoes numerous changes to its physiology and metabolic processes to survive the winter months, including adaptations that let them endure whole-body freezing. The regulation of key enzymes of central carbohydrate metabolism in the liver plays a crucial role in mediating the synthesis and maintenance of high concentrations of glucose as a cryoprotectant during freezing as well as glucose reconversion to glycogen after thawing. The present study characterized the regulation of fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11) from wood frog liver during freezing, FBPase being a crucial enzyme regulating gluconeogenesis. Liver FBPase was purified to homogeneity from control and frozen wood frogs by a one-step chromatographic process. Kinetic and regulatory parameters of the enzyme were investigated and demonstrated a significant decrease in sensitivity to its substrate fructose-1,6-bisphosphatein the liver of frozen frogs, as compared with controls. Immunoblotting also revealed freeze-responsive changes in posttranslational modifications with a significant decrease in serine phosphorylation (by 53%) for FBPase from frozen frogs. Taken together, these results suggest that FBPase is suppressed, and gluconeogenesis is inhibited during freezing. This response acts as an important component of the metabolic survival strategy of the wood frog.

MdSWEET17, a sugar transporter in apple, enhances drought tolerance in tomato

Sugars are important energy source and signaling molecule in plant, and sugar transporters such as SWEET (sugars will eventually be exported transporters) play important roles in plant growth and development as well as biotic and abiotic stresses. In this study, a gene named MdSWEET17 was isolated from apple (Malus×domestic). Expression analysis suggested that MdSWEET17 expressed in all tested tissues (root, stem, leaf, flower and fruit) and the transcript levels were different. Furthermore, MdSWEET17 transgenic tomatoes and wild type were treated with drought. The results showed transgenic lines had higher drought tolerance and accumulated more fructose. Taken together, these findings indicated that MdSWEET17 take part in drought stress response and the regulation of fructose.

Regulation of Fructose 1,6-Bisphosphatase Activity of Chlorella by Mole Mass Change

Fast protein liquid chromatography on Superose 6 of partially purified FBPase II from Chlorella reveals a 1350 kDa-form at pH 6.0 and a 67 kDa-form at pH 8.5. Treatment of the large enzyme form with 5mᴍ concentrations of Mg2+, F1,6P2, DTT or ATP leads to dissociation into smaller ones of 215 -470 kDa. Aggregation/dissoziation is a reversible process, as has been shown for the effect of F1,6P2 and of pH, by rechromatography. The change in mole mass results in alterations of the activitiy and of the kinetic properties of the enzyme forms, obtained. Dissociation results in a 4 - 6 fold increase in activity, as can be shown for F1,6P2-treated samples. Halfsaturation constants, as well as the degree of cooperativity of the 67- and the 1350- kDa form, are different for substrate affinity, activation by Mg2+ and DTT, and for inhibition by ATP. Both enzyme forms hydrolyse fructose 1,6 bisphosphate and seduheptulose 1,7 bisphosphate better than other phosphorylated compounds. The ratio of F1,6P2- to SDP-cleavage is 100:58 for the small enzyme form and 100: 84 for the large one. Activation of FBPase II in the light and inactivation in the dark is discussed on the basis of different oligomeric forms of the enzyme, generated by changes in the concentration of intermediates and effectors in the chloroplast stroma, leading to dissociation or aggregation. The conclusion is drawn that oligomerization of key enzymes, resulting in enzyme forms with different activities and different kinetic properties, might provide an effective mechanism for enzyme regulation in vivo

Kinetics and regulation of fructose and glucose transport systems are responsible for fructophily in Zygosaccharomyces bailii

A strain of Zygosaccharomyces bailii was selected for studies on fructose and glucose transport to determine the basis of the fructophilic behaviour of this species. Fructose was transported by a specific low-affinity, high-capacity transport system with a K m of 65.6 mM and a V max of 6.7 mmol g-1 h-1 for cells grown on 2% (w/v) fructose, while the transport of glucose showed a K m of 7 mM and a V max of 1.7 mmol g-1 h-1 for cells grown on 2% (w/v) glucose. The transporter of glucose also fructose as a substrate. Fructose inactivated the glucose transporter; inactivation was faster at higher concentrations. Both transporters were partially inductive. Measurements of metabolic fluxes and respiration and fermentation rates supported the general features identified by transport measurements. The kinetics and regulation of transport of the two sugars confirm the fructophilic behaviour previously described by other authors.

Photoactivation and Regulation of Spinach Leaf Fructose 1,6-bisphosphatase

Fructose 1,6-bisphosphatase, in isolated intact chloroplast from spinach leaves, is photoactivated by ferredoxin/thioredoxin system. The mechanism involved is conversion of enzyme disulfide to sulfhydryl groups as the photoactivation is inhibited by sulfhydryl group modifying agents which are able to penetrate the chloroplast envelope. Reduction of ferredoxin on the reducing side of photosystem I is found to be a key event and active electron flow to ferredoxin must be maintained for keeping the enzyme in activated state. DCMU - a classical electron transport chain inhibitor and other exogenously added electron acceptors, which intercept electrons on or before ferredoxin cause deactivation of fructose 1,6-bisphosphatase in light. The rate of deactivation, in dark, is also enhanced by exogenously added electron acceptors and sulfhydryl group modifying agents. The mechanism of regulation of fructose 1,6-bisphosphatase is discussed.

Characterization of phosphofructokinase II and regulation of fructose 2,6-bisphosphate levels in Trichoderma reesei.

Phosphofructokinase II (PEK II) from Trichoderma reesei was partially purified (247-fold). The calculated Km values for fructose 6-phosphate and ATP were 0.7 mM and 40 microM, respectively. Upon incubation in the presence of [gamma-32P]ATP, the enzyme formed a radioactive phosphoprotein with molecular mass of 67 kDa in autoradiography analysis after SDS-PAGE. Upon incubation in the presence of ATP-Mg and the catalytic subunit of cAMP-dependent protein kinase, its activity was not modified. The same result was obtained when a cell-free extract of T. reesei was incubated with ATP-Mg and cAMP. 2,4-Dinitrophenol caused a transient rise in cAMP levels in the fungal cell. The results provide evidence that the fructose 2,6-bisphosphate level in T. reesei is independent of cAMP concentrations and not related to a cAMP-dependent mechanism, but to the availability of substrate fructose 6-phosphate.

Regulation of fructose 2,6-bisphosphate in perfused flight muscle of the locust, Locusta migratoria: the effect of octopamine.

Conference Article| April 01 1991 Regulation of fructose 2,6-bisphosphate in perfused flight muscle of the locust, Locusta migratoria: The effect of octopamine CORNELIA BLAU; CORNELIA BLAU 1Institut für Zoologie, Johannes Gutenberg-Universität Mainz, Saarstrasse 21, D-6500 Mainz, F.R.G. Search for other works by this author on: This Site PubMed Google Scholar DAVID J. CANDY; DAVID J. CANDY *School of Biochemistry, University of Birmingham, P.O. Box 363, Birmingham B15 2TT, U.K. Search for other works by this author on: This Site PubMed Google Scholar GERHARD WEGENER GERHARD WEGENER 1Institut für Zoologie, Johannes Gutenberg-Universität Mainz, Saarstrasse 21, D-6500 Mainz, F.R.G. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1991) 19 (2): 136S. https://doi.org/10.1042/bst019136s Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation CORNELIA BLAU, DAVID J. CANDY, GERHARD WEGENER; Regulation of fructose 2,6-bisphosphate in perfused flight muscle of the locust, Locusta migratoria: The effect of octopamine. Biochem Soc Trans 1 April 1991; 19 (2): 136S. doi: https://doi.org/10.1042/bst019136s Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1991 Biochemical Society1991 Article PDF first page preview Close Modal You do not currently have access to this content.

Regulation of fructose 2,6-bisphosphate levels in cold-acclimated brown adipose tissue of rat

The effects of cold exposure and T 4, administration on fructose 2,6-bisphosphate levels, phosphofructokinase-2 and pyruvate kinase activities were examined in rat brown adipose tissue. Cold adaptation (14 days) gave rise to a 2-fold increase in the amount of fructose 2,6-bisphosphate and phosphofructokinase-2 activity, and increased the pyruvate kinase activity 4-fold. If, in addition, the cold-acclimated rats were treated with T 4, these parameters were again significantly enhanced. The effect on phosphofructokinase-2 was on the V max, without modification of the K m (for both fructose 6-phosphate and ATP) of the enzyme. In the hypothyroid state, however, the activity of pyruvate kinase remains unchanged. These data support previous observations on stimulation of glycolytic flux during cold adaptation in brown adipose tissue, and a permissive role of thyroid hormones in the process.

Regulation of fructose 2,6-biphosphate levels in Neurospora crassa

Both wild type and cr-1 mutant (adenylate cyclase and cyclic AMP-deficient) strains of Neurospora crassa contain fructose 2,6-biphosphate at levels of 2t nmol/g dry tissue weight. This level decreases by about 50% in both strains upon depriving the cells of carbon or nitrogen sources for 3 h. An increase in cyclic AMP levels produced by addition of lysine to nitrogen-starved cells produced no increase in fructose 2,6-biphosphate levels. Both strains respond to short-term addition of salicylate, acetate, or 2,4-dinitrophenol with an increase in fructose 2,6-biphosphate. Thus, the above-described regulation of fructose 2,6-biphosphate levels is cyclic AMP-independent. A suspension of the wild type produces a transient increase of fructose 2,6-biphosphate in response to administration of glucose, whereas the mutant strain does not respond unless it is fed exogenous cyclic AMP. Substitution of acetate for sucrose as a sole carbon source for growth leads to a differential decrease in fructose 2,6-biphosphate levels between the two strains: the wild type strain has 63% and the cr-1 mutant strain has 37% of the levels of fructose 2,6-biphosphate on acetate as compared to sucrose-grown controls. This may be the basis for an advantage of cr-1 over wild type in growth on acetate. Thus, although most regulation of fructose 2,6-biphosphate is cyclic AMP-independent, the levels can be regulated by a combination of carbon source and cyclic AMP levels.

Regulation of fructose 2,6-bisphosphate metabolism in human fibroblasts

In the present work, the mechanism involved in the regulation of fructose 2,6-bisphosphate (fructose-2,6- P 2) metabolism in human fibroblasts has been studied. Various agents like serum, insulin and adrenaline known to affect glycolysis have been investigated for their ability to influence fructose 2,6- P 2 metabolism in confluent human fibroblasts. Serum appears to be the most potent activator of fructose-2,6- P 2 levels and capable of inducing a marked increase in 6-phosphofructo-2-kinase (ATP: d-fructose-6-phosphate-2-phosphotransferase), EC 2.7.1. 105). To a lesser extent insulin has the same effects. The increase in enzyme activity elicited by serum and insulin does not require de novo protein synthesis since the process is insensitive to cycloheximide. Incubation of fibroblasts in the presence of adrenaline is responsible for a significant rise in fructose-2,6- P 2 levels without affecting 6-phosphofructo-2-kinase. Similar experiments performed on glucose-starved or cytochalasin B-treated cells show that the effects elicited by all the agents are strictly dependent on glucose availability.

Regulation of fructose 2,6-bisphosphate concentration in white adipose tissue.

Injection of insulin to fed rats diminished the concentration of fructose 2,6-bisphosphate in white adipose tissue. Incubation of epididymal fat-pads or adipocytes with insulin stimulated lactate release and sugar detritiation and also decreased fructose 2,6-bisphosphate concentration. Such a decrease was, however, not observed in fat-pads from starved or alloxan-diabetic rats. Incubation of adipocytes from fed rats with various concentrations of glucose or fructose led to a dose-dependent rise in fructose 2,6-bisphosphate which correlated with lactate output and detritiation of 3-3H-labelled sugar. In adipocytes from fed rats, palmitate stimulated the detritiation of [3-3H]glucose without affecting lactate production and fructose 2,6-bisphosphate concentration. Incubation of epididymal fat-pads from fed rats in the presence of antimycin stimulated lactate output but decreased fructose 2,6-bisphosphate concentration. Changes in lipolytic rates brought about by noradrenaline, insulin, adenosine and corticotropin in adipocytes from fed rats were not related to changes in fructose 2,6-bisphosphate or to rates of lactate output. In fed rats, the activity of 6-phosphofructo-2-kinase was not changed after treatment of adipocytes with insulin, noradrenaline or adenosine. It is suggested that the decrease in fructose 2,6-bisphosphate concentration observed after insulin treatment can be explained by the increase in sn-glycerol 3-phosphate, an inhibitor of 6-phosphofructo-2-kinase.

Regulation of fructose 2,6-bisphosphate concentration in spinach leaves.

Fructose-6-phosphate 2-kinase and fructose-2,6-bisphosphatase have been partially purified from spinach leaves and their regulatory properties studied. Fructose-6-phosphate 2-kinase was activated by phosphate and fructose 6-phosphate, and inhibited by 3-phosphoglycerate and dihydroxyacetone phosphate. Fructose-2,6-bisphosphatase was inhibited by fructose 6-phosphate and phosphate. The interaction between these effectors was studied when they were varied, alone or in combination, over a range of concentrations representative of those in the cytosol of spinach leaf cells. In conditions when dihydroxyacetone phosphate or 3-phosphoglycerate rise, as is typical during photosynthesis, the fructose 2,6-bisphosphate level will decrease, which will favour sucrose synthesis. In conditions when fructose 6-phosphate accumulates, fructose 2,6-bisphosphate should rise, which will favour a restriction of sucrose synthesis and promotion of starch synthesis.

Regulation of fructose 2,6-P 2 concentration in isolated hepatocytes

The effect of hormones on fructose-2,6-P 2 level and fructose-6-P,2-kinase activity was examined using rat hepatocytes. The dose response curve shows the half-maximal effect of glucagon on fructose-2,6-P 2 occurs at 3 X 10 −13 M glucagon, whereas the half-maximal effect on cyclic AMP occurs at 3 × 10 −0 M. The decrease in fructose-2,6-P 2 parallels the decrease in fructose-6-P,2-kinase activity. Incubation of cells with dibutryl cyclic AMP and cyclic AMP results in a 2- to 3-fold decrease in fructose-2,6-P 2. Epinephrine (10 −5 M) mediates a 2-fold decrease in fructose-2,6-P 2; isoproterenol has no effect. These results suggest that regulation of fructose-6-P,2-kinase is complex, involving cyclic AMP-dependent and -independent mechanisms.

Regulation of fructose 1,6-bisphosphatase by histidine under gluconeogenic conditions

Regulation of fructose 1,6-bisphosphatase by histidine under gluconeogenic conditions

Regulation of fructose, 1,6-bisphosphatase by histidine under gluconeogenic conditions.

Fructose 1,6-bisphosphatase (EC 3.1.3.11) requires a free divalent metal and a metal chelate for optimum activity in the neutral pH range. The latter requirement can be satisfied by histidine, which appears to function as the chelating metabolite in vivo. Under fasting conditions, the concentrations of histidine in rabbit liver vary in the range required for activation of fructose bisphosphatase, and the enzyme itself is modified so that it becomes more responsive to histidine.