Search results for "6-Bisphosphate"

Flying insects: model systems in exercise physiology

1996

Insect flight is the most energy-demanding exercise known. It requires very effective coupling of adenosine triphosphate (ATP) hydrolysis and regeneration in the working flight muscles.31P nuclear magnetic resonance (NMR) spectroscopy of locust flight muscle in vivo has shown that flight causes only a small decrease in the content of ATP, whereas the free concentrations of inorganic phosphate (P i ), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were estimated to increase by about 3-, 5- and 27-fold, respectively. These metabolites are potent activators of glycogen phosphorylase and phosphofructokinase (PFK). Activation of glycolysis by AMP and P i is reinforced synergistica…

Fructose-1,6-Bisphosphate Protects Hippocampal Rat Slices from NMDA Excitotoxicity

2019

Effects of fructose 1,6-bisphosphate (F-1,6-P2) towards N-methyl-d-aspartate NMDA excitotoxicity were evaluated in rat organotypic hippocampal brain slice cultures (OHSC) challenged for 3 h with 30 &mu

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

1991

Antagonistic effects of hypertrehalosemic neuropeptide on the activities of 6-phosphofructo-1-kinase and fructose-1,6-bisphosphatase in cockroach fat…

2001

Hypertrehalosemic neuropeptides from the corpora cardiaca such as the decapeptide Bld HrTH bring about a profound switch in the metabolic activity of cockroach fat body during which production of the blood sugar trehalose is stimulated while the catabolism of carbohydrate (glycolysis) is inhibited. The mechanisms of the metabolic switch are not fully understood. Incubation of isolated fat body from the cockroach Blaptica dubia with 10(-8) M Bld HrTH, for 10-60 min, stimulated glycogen breakdown and increased the content of the substrates of both the glycolytic enzyme 6-phosphofructo-1-kinase (PFK, EC 2.7.1.11) and the gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase, EC 3.1.3.11) in…

Thimerosal induces calcium mobilization, fructose 2,6-bisphosphate synthesis and cytoplasmic alkalinization in rat thymus lymphocytes

1991

The effect of thimerosal on intracellular calcium ([Ca2+]i), pH (pHi) and fructose 2,6-bisphosphate (Fru 2,6-P2) in thymus lymphocytes was investigated. The effect of thimerosal on cell growth was also examined. Thimerosal produced a dose-dependent increase in [Ca2+]i, pHi and in the level of fructose 2,6-bisphosphate. Thimerosal was, however, unable to produce cell proliferation and inhibited [3H]thymidine incorporation when cells were challenged with PHA and costimulator. In the absence of external calcium, thimerosal produced only a slight increase in [Ca2+]i. In Na(+)-containing buffer, thimerosal induced an initial acidification (0.05 +/- 0.01 pH units), followed by an alkalinization o…

Conformational response to ligand binding in phosphomannomutase2: insights into inborn glycosylation disorder.

2014

Background: Mutations in phosphomannomutase2 cause glycosylation disorder, a disease without a cure that will largely benefit from accurate ligand-bound models. Results: We obtained two models of phospomannomutase2 bound to glucose 1,6-bisphosphate and validated them with limited proteolysis. Conclusion: Ligand binding induces a large conformational transition in PMM2. Significance: We produce and validate closed-form models of PMM2 that represent a starting point for rational drug discovery.

Coordination and Integration of Metabolism in Insect Flight*

1997

Abstract Insect flight is the most energy-demanding activity of animals. It requires the coordination and cooperation of many tissues, with the nervous system and neurohormones controlling the performance and energy metabolism of muscles, and of the fat body, ensuring that the muscles and nerves are supplied with essential fuels throughout flight. Muscle metabolism can be based on several different fuels, the proportions of which vary according to the insect species and the stage in flight activity. Octopamine, which acts as neurotransmitter, neuromodulator or neurohormone in insects, has a central role in flight. It is present in brain, ventral ganglia and nerves, supplying peripheral tiss…

The regulation of trehalose metabolism in insects.

1996

Trehalose is a non-reducing disaccharide comprising two glucose molecules. It is present in high concentration as the main haemolymph (blood) sugar in insects. The synthesis of trehalose in the fat body (an organ analogous in function to a combination of liver and adipose tissue in vertebrates) is stimulated by neuropeptides (hypertrehalosaemic hormones), released from the corpora cardiaca, a neurohaemal organ associated with the brain. The peptides cause a decrease in the content of fructose 2,6-bisphosphate in fat body cells. Fructose 2,6-bisphosphate, acting synergistically with AMP, is a potent activator of the glycolytic enzyme 6-phosphofructokinase-1 and a strong inhibitor of the gluc…

6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase from frog skeletal muscle: purification, kinetics and immunological properties.

1993

Fructose 2,6-bisphosphate is the most potent activator of 6-phosphofructo-1-kinase, a key regulatory enzyme of glycolysis in animal tissues. This study was prompted by the finding that the content of fructose 2,6-bisphosphate in frog skeletal muscle was dramatically increased at the initiation of exercise and was closely correlated with the glycolytic flux during exercise. 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, the enzyme system catalyzing the synthesis and degradation of fructose 2,6-bisphosphate, was purified from frog (Rana esculenta) skeletal muscle and its properties were compared with those of the rat muscle type enzyme expressed in Escherichia coli using recombinant DN…

Fructose 2,6-bisphosphate as a signal for changing from sugar to lipid oxidation during flight in locusts

1986

AbstractFlight in locusts is initially powered mainly by carbohydrate but if flight is to be sustained, as in migration, the animals have to utilize fat as the predominant fuel. The molecular basis of this metabolic switch has not been identified. Fructose 2,6-bisphosphate is a potent activator of 6-phosphofructokinase (EC 2.7.1.11) purified from locust flight muscle. After the first few minutes of flight in the locust the concentration of fructose 2,6-bisphosphate in the flight muscle falls dramatically, which should lead to a decrease in the activity of 6-phosphofructokinase as part of the mechanism to conserve carbohydrate during prolonged flight.