Therapeutic action of fructose-1,6-diphosphate in traumatic shock.
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “Fructosediphosphates”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Biochemical observations on a case of hepatic fructose-1,6-diphosphatase deficiency.
A case of hepatic fructose-1,6-diphosphatase deficiency is described. She presented with congenital bilateral cataracts, failure to thrive, hypoglycaemia and hyperlactacidaemia. A liver biopsy revealed normal levels of gluconeogenic enzymes except fructose-1,6-diphosphatase which was present at 30% of the level of the lower control values. The residual activity had a normal affinity for fructose-1,6-diphosphate, a decreased sensitivity for inhibition by fructose-2,6-diphosphate and an increased resistance toward conversion to the AMP-insensitive form of the enzyme. As a result of this mutation, the residual FDPase will always be maintained in the AMP-inhibited form.
Adenosine Monophosphate↗
The involvement of fructose 2,6-bisphosphate in substrate cycle control in the nonoxidative stage of the pentose phosphate pathway. A phosphorus magnetic resonance spectroscopy study.
The role of fructose 2,6-bisphosphate in the interconversion of sedoheptulose 7-phosphate and sedoheptulose 1,7-bisphosphate in rat liver cytosol fractions was studied by means of phosphorus magnetic resonance spectroscopy. When the activity of 6-phosphofructo-1-kinase was inhibited by a high concentration of ATP, the addition of fructose 2,6-bisphosphate led to a marked decrease in sedoheptulose 7-phosphate levels, accompanied by an increased concentration of ADP. Fructose 2,6-bisphosphate essentially inhibited both the decrease in sedoheptulose 1,7-bisphosphate concentration and the accumulation of Pi in the incubation mixture. The data provided evidence that fructose 2,6-bisphosphate can regulate the substrate cycle: sedoheptulose 7-phosphate<-->sedoheptulose 1,7-bisphosphate in the liver, and thus control the flux through the nonoxidative stage of the pentose phosphate pathway.
Animals↗
Fructose-1,6-diphosphate reduces acute ECG changes due to doxorubicin in isolated rat heart.
Doxorubicin (DXR) (0.17 x 10(-4) M) induces an acute cardiotoxicity in isolated rat heart; there is a progressive widening of the S alpha T segment, with a decrease in force derivatives and in the coronary flow. Concurrent perfusion with fructose-1,6-diphosphate (FDP) (10(-5)-10(-4) M) dose-dependently reduces the S alpha T enlargement but fails to affect the reduction in force derivatives and coronary flow. The target of cardiac protection by FDP might be the ionic mechanisms underlying the action potential configuration.
Animals↗
Proton and potassium fluxes in rat red blood cells incubated with sugar phosphates.
Fructose-1,6-diphosphate counteracts potassium ejection and proton uptake induced in rat red blood cells by valinomycin and an uncoupler. The effect on potassium ejection is reduced in the presence of ouabain and divalent cations.
Animals↗
Nutrient metabolism in islet cells.
Explore the source record for details and available documents.
Adenosine Triphosphatases↗
Synergistic effect of AMP and fructose 2,6-bisphosphate on the protection of fructose 1,6-bisphosphatase against inactivation by trypsin.
The rate of inactivation of chicken liver fructose 1,6-bisphosphatase by trypsin is reduced if the digestive reaction is conducted in the presence of AMP or fructose 2,6-bisphosphate. The effects of these 2 compounds are synergistic. Although fructose 1,6-bisphosphate does not protect the enzyme against tryptic inactivation, it can enhance the effect of AMP. Selective modification of the AMP allosteric site of fructose 1,6-bisphosphatase with pyridoxal-P and NaBH4 renders the enzyme more resistant to tryptic inactivation, but the modified enzyme is no longer responsive to the protective effect of AMP.
Adenosine Monophosphate↗
Is it possible to maintain a normal glutathione level in lenses in vitro?
In most types of experimentally induced cataracts, glutathione (GSH) content decreases considerably before the onset of opacity. GSH may provide a protective function for protein SH groups by scavenging oxidative products that may impair lens metabolism. To avoid impairment of lens metabolism by decreased levels of GSH it may be possible in vitro: (1) to stimulate GSH synthesis by enrichment of the incubation medium with the amino acids necessary for GSH synthesis or (2) to enrich the incubation medium with the tripeptide itself so that it can be taken up by the lens. Both approaches were investigated with bovine lenses. Lenses were incubated in pairs in a salt solution without carbohydrates, so as to deplete lens of GSH. Following starvation, one lens of each pair was incubated for recovery in TCM 199 enriched with MgSO4 and the three amino acids of GSH; the other lens was put into a freshly prepared salt solution. After 6 h, lenses from the recovery solution contained more GSH than the other lenses. Addition of fructose-1,6-diphosphate to the medium enhanced this effect. When, after starvation, lenses were incubated in the presence of different amounts of GSH, GSH lens content rose, with the highest in those lenses incubated in a medium with a final molarity of 4 X 10(-3) M GSH. Therefore, incubation of lenses depleted of GSH in medium with either the amino acids of GSH or GSH itself appear to facilitate recovery of GSH content.
Animals↗
Comparative inactivation and inhibition of the anomerase and isomerase activities of phosphoglucose isomerase.
Several metabolic compounds have been found to be competitive inhibitors of the anomerase activity of phosphoglucose isomerase (EC 5.3.1.9).Ki values for erythrose 4-phosphate, 6-phosphogluconate, and fructose 1,6-bisphosphate for the anomerase reaction are 0.32 muM, 21 muM, and 84 muM respectively at 0 degree and pH 8.2. A significant difference between the fructose 1,6-bisphosphate inhibition constants for both activities was found (Ki(isomerase) = 800 muM and Ki(anomerase) = 140 muM). Also the Km values for both activities were found to be significantly different (Km(isomerase) = 140 muM and Km(anomerase) = 3.6 muM). Attempts to independently alter the anomerase to isomerase activity ratio through protein modification yielded mixed results. While several modifying reagents destroyed the catalytic activities at identical rates, inactivation by iodoacetamide or pyridoxal 5' phosphate sensitized photo-oxidation displayed differential initial effects on the two activities with the anomerase activity being the less affected. These data support the theory that an imidazole residue is catalytically important for isomerization, but less so for anomerization.
Animals↗
Active glycolysis and glycogenolysis in early stages of primary cultured hepatocytes. Role of AMP and fructose 2,6-bisphosphate.
This study examines the factors involved in the rapid glycolysis and glycogenolysis that occur during the first stages of hepatocyte culture: a) Shortly after seeding glycolysis, estimated as lactate released to culture medium, increased 10 times in comparison to that reported in vivo. By 8 to 9 h of culture, hepatocytes were nearly glycogen-depleted even in the presence of insulin. b) 6-Phosphofructo-2-kinase remained 100% active during this period. The proportion of the initial active phosphorylase (87%) decreased to 57% by 7 h of culture. c) Fructose 2,6-bisphosphate content was initially similar to that found in liver of fed animals, decreased after seeding and increased thereafter up to four times the initial concentration. In spite of changes in the concentration of this activator, the glycolytic rate remained high and constant. d) ADP and AMP increased sharply after cell plating, reaching values 1.7 and 3.5 times higher. The rise in AMP levels may be involved in the activation of glycolysis and glycogenolysis, because this metabolite is known to act as an allosteric activator of phosphofructokinase and glycogen phosphorylase. This metabolic situation resembles that of cells under hypoxia.
Adenosine Diphosphate↗
Beneficial effects of fructose-1,6-diphosphate infusion on liver regeneration after ischemic liver injury.
The effect of fructose-1,6-diphosphate (FDP) on cellular viability after partial hepatectomy in partial ischemic liver was investigated in rats. The administration of FDP did not increase blood flow in the hepatic tissue; however, it significantly suppressed the elevation of serum liver functions for 24 hours after partial hepatectomy. Levels of DNA synthesis, protein synthesis, and labeling index were significantly higher in the groups administered divided doses of FDP before and after partial hepatic ischemia than in the control group (P less than 0.01). Thus, these findings indicate that FDP has cytoprotective and hepatotrophic effects on liver with ischemic injury and that divided dose administration of FDP is more effective than bolus doses in decreasing damage following ischemic and reperfusion injury.
Animals↗
Immobilization of pig muscle aldolase on a silica-based support.
Pig muscle aldolase was covalently attached to a silica-based support possessing aldehyde functional groups. The activity of the immobilized enzyme was 37 U/g solid, and the specific activity calculated on a bound protein basis was 1.9 U/mg protein. The optimum pH for the catalytic activity was pH 7.5. The apparent optimum temperature was found to be 45 degrees C. The Km app value of the immobilized aldolase with D-fructose 1,6-diphosphate as substrate was 1.25 X 10(-4) M. The conformational stability was improved by the immobilization. The immobilized aldolase was used for the continuous splitting of D-fructose 1,6-diphosphate.
Animals↗
Fusion and metabolism of plant cells as affected by microgravity.
Plant cell protoplasts derived from leaf tissue of two different tobacco species (Nicotiana tabacum., N. rustica L.) were exposed to short-term (sounding rocket experiments) and long-term (spacelab) microgravity environments in order to study both (electro) cell fusion and cell metabolism during early and later stages of tissue regeneration. The period of exposure to microgravity varied from 10 min (sounding rocket) to 10 d (space shuttle). The process of electro fusion of protoplasts was improved under conditions of microgravity: the time needed to establish close membrane contact between protoplasts (alignment time) was reduced (5 as compared to 15 s under 1 g) and numbers of fusion products between protoplasts of different specific density were increased by a factor of about 10. In addition, viability of fusion products, as shown by the ability to form callus, increased from about 60% to more than 90%. Regenerated fusion products obtained from both sounding-rocket and spacelab experiments showed a wide range of intermediate properties between the two parental plants. This was verified by isozyme analysis and random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). In order to address potential metabolic responses, more general markers such as the overall energy state (ATP/ADP ratio), the redox charge of the diphosphopyridine nucleotide system (NADH/NAD ratio), and the pool size of fructose-2,6-bisphosphate (Fru 2,6 bisp), a regulator of the balance between glycolysis and gluconeogenesis, were determined. Responses of these parameters were different with regard to short-term and long-term exposure. Shortly after transition to reduced gravitation (sounding rocket) ratios of ATP/ADP exhibited strong fluctuation while the pool size of NAD decreased (indicating an increased NADH/NAD ratio) and that of Fru 2,6 bisp increased. As similar changes can be observed under stress conditions, this response is probably indicative of a metabolic stress compensation. Samples taken for up to 7 d of exposure to microgravity showed the opposite effect. Here, the ratios of ATP/ADP and of NADH/NAD, and the pool size of Fru 2,6 bisp were decreased. We take this an an indication of metabolic relaxation, i.e. decreased metabolic turnover. As rates of protoplast regeneration and cell division were obviously similar to 1-g controls, we conclude that under conditions of microgravity regenerating tobacco mesophyll protoplasts need less metabolic energy for the same effort.
Adenine Nucleotides↗
Tungstate is an effective antidiabetic agent in streptozotocin-induced diabetic rats: a long-term study.
AIMS/HYPOTHESIS: Recent studies have shown the anti diabetic effects of oral sodium tungstate treatment in several animal models of diabetes based on short-term experiments. In this study, we examined the effectiveness of long-term tungstate treatment of streptozotocin-induced-diabetic rats. METHODS: Tungstate was administered to the drinking water of rats for eight months. RESULTS: The treatment resulted in a reduction in serum glucose concentrations in diabetic rats, but no change in glycaemia was detected in healthy rats. Alterations in the hepatic glucose metabolism due to diabetes were almost completely counteracted by tungstate treatment. The partial recovery of glucokinase activity, not found in diabetic animals, normalised glycogen and glucose 6-phosphate concentrations. Tungstate treatment also restored pyruvate kinase activity and fructose 2,6-bisphosphate concentrations. In healthy rats, tungstate treatment did not modify the majority of the hepatic parameters studied. Moreover, tungstate treatment prevented diabetes-induced morphological changes in the kidney and ocular lens and also reduced mortality. Furthermore, no hypoglycaemic episodes or undesirable side effects were observed in treated diabetic or healthy rats. In addition, there is no evidence of intolerance developing after prolonged use. CONCLUSION/INTERPRETATION: Tungstate could play a helpful part in the long-term treatment of diabetes.
Aging↗
Fructose-1,6-bisphosphate inhibits the expression of inducible nitric oxide synthase caused by oxygen-glucose deprivation through the inhibition of glutamate release in rat forebrain slices.
Fructose-1,6-bisphosphate (FBP) is a glycolytic pathway intermediate with a neuroprotective action in animal models of brain ischaemia. We addressed the question of whether FBP acts through inhibiting inducible nitric oxide synthase (iNOS) expression via reduction of glutamate release, since we have recently demonstrated that glutamate is involved in the expression of iNOS. FBP (5 mM) added to the incubation solution of rat forebrain slices subjected to oxygen-glucose deprivation (OGD) inhibited glutamate release significantly (around 40%). FBP also inhibited the induction of the calcium-independent NOS activity and reduced the levels of iNOS protein in rat forebrain slices subjected to OGD. We conclude that the action of FBP by reducing glutamate release and iNOS expression, both of which have been implicated in cell damage, is a reason for further evaluation of FBP as a neuroprotectant.
Amino Acids, Essential↗
The diversion of lactose carbon through the tagatose pathway reduces the intracellular fructose 1,6-bisphosphate and growth rate of Streptococcus bovis.
Twenty strains of Streptococcus bovis grew more slowly on lactose (1.21 +/- 0.12 h-1) then than on glucose (1.67 +/- 0.12 h-1), and repeated transfers or prolonged growth in continuous culture (more than 200 generations each) did not enhance the growth rate on lactose. Lactose transport activity was poorly correlated with growth rate, and slow growth could not be explained by the ATP production rate (catabolic rate). Batch cultures growing on lactose always had less intracellular fructose 1,6-bisphosphate (Frul,6P2) than cells growing on glucose (6.6 mM compared to 16.7 mM), and this difference could be explained by the pathway of carbon metabolism. Glucose and the glucose moiety of lactose were metabolized by the Embden-Meyerhoff-Parnas (EMP) pathway, but the galactose moiety of lactose was catabolized by the tagatose pathway, a scheme that by-passed Frul,6P2. A mutant capable of co-metabolizing lactose and glucose grew more rapidly when glucose was added, even though the total rate of hexose fermentation did not change. Wild-type S. bovis grew rapidly with galactose and melibiose, but these galactose-containing sugars were activated by galactokinase and catabolized via EMP. On the basis of these results, rapid glycolytic flux through the EMP pathway is needed for the rapid growth (more than 1.2 h-1) of S. bovis.
Adenosine Triphosphate↗
Enzyme activity of lectins from the nitrogen-fixing soil bacterium Bacillus polymyxa.
Lectins LI and LII, localized on the surface of the nitrogen-fixing soil bacterium Bacillus polymyxa 1460, were shown to possess proteolytic activity. A relationship was found between the proteolytic and hemagglutinating activities of the lectins. Blocking of hemagglutinating activity with specific carbohydrate haptens led to significant changes in the enzyme activity of both lectins. When lectin activity was blocked with glucuronic acid and fructose-1, 6-diphosphate, the proteolytic activity of both LI and LII declined, whereas incubation with d-galactosamine and d-glucosamine promoted increases in the proteolytic activity of LII. This study proposes that the molecules of the B. polymyxa lectins may have two centers on their surfaces: one responsible for lectin activity and the other for proteolytic activity.
Bacillus↗
Adrenergic regulation of Rana balcanica erythrocyte pyruvate kinase.
The regulation of pyruvate kinase activity by noradrenaline was investigated in Rana balcanica red cells. Thirty minutes of noradrenaline incubation induced a significant increase in the Vo/Vmax ratio of pyruvate kinase. The S0.5 for phosphoenolpyruvate of the enzyme significantly increased in the presence of noradrenaline while the Km for ADP decreased. In response to hormonal stimulation the Na +/H+ exchange was activated as was shown by the increase in Na+ and cyclic adenosine monophosphate from the 3rd min of incubation. All these effects were specific to alpha1 and beta antagonists. High concentrations of fructose diphosphate significantly activated the enzyme in the presence of noradrenaline but not in its absence. Furthermore, the presence of noradrenaline partially released the inhibition of the enzyme by adenosine triphosphate, inorganic phosphate and 2,3-diphosphoglycerate. The results suggest that noradrenaline stimulates glycolysis through pyruvate kinase activation. The mechanism of stimulation may is through Na+/H+ exchange activation, cyclic adenosine monophosphate concentration and Na(+)-K(+)-ATPase activation.
2,3-Diphosphoglycerate↗