Role of pyruvate kinase, phosphoenolpyruvate carboxykinase, malic enzyme and lactate dehydrogenase in anaerobic energy metabolism ofTubifex spec

1979 ◽  
Vol 130 (4) ◽  
pp. 337-345 ◽  
Author(s):  
K. H. Hoffmann ◽  
T. Mustafa ◽  
J. B. J�rgensen
Keyword(s):  
Lactate Dehydrogenase ◽  
Energy Metabolism ◽  
Pyruvate Kinase ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Anaerobic Energy

Respiration and carbohydrate energy metabolism of the lung-dwelling parasite Rhabdias bufonis (Nematoda: Rhabdiasoidea)

Parasitology ◽  
1978 ◽  
Vol 76 (1) ◽  
pp. 21-27 ◽  
Author(s):  
A. O. Anya ◽  
G. M. Umezurike
Keyword(s):  
Lactate Dehydrogenase ◽  
Energy Metabolism ◽  
Malate Dehydrogenase ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Weight Basis ◽  
Fresh Weight ◽  
Fresh Weight Basis ◽  
Alternative Pathways

SummaryAn investigation of the carbohydrate energy metabolism of Rhabdias bufonis, the lung-dwelling nematode parasite of the African toad, Bufo regularis, indicates that the nematode stores very little glycogen (0·137 ± 0·003% on a fresh weight basis) but does utilize oxygen in vitro. The intracellular distribution and high levels of activity observed for the enzymes phosphoenolpyruvate carboxykinase, pyruvate kinase, lactate dehydrogenase, malate dehydrogenase, malic enzyme and fumarate reductase suggest two alternative pathways of carbohydrate energy metabolism.

Renal enzymes during experimental diabetes mellitus in the rat. Role of insulin, carbohydrate metabolism, and ketoacidosis

1984 ◽  
Vol 62 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Guy Lemieux ◽  
Manuel Rengel Aranda ◽  
Pierrette Fournel ◽  
Christiane Lemieux
Keyword(s):  
Lactate Dehydrogenase ◽  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Malate Dehydrogenase ◽  
Ammonium Chloride ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Diabetic Rats ◽  
Additional Role

The activities of various ammoniagcnic, gluconeogenic, and glycolytic enzymes were measured in the renal cortex and also in the liver of rats made diabetic with streptozotocin. Five groups of animals were studied: normal, normoglycemic diabetic (insulin therapy), hyperglycemic, ketoacidotic, and ammonium chloride treated rats. Glutaminase I, glutamate dehydrogenase, glutamine synthetase, phosphoenolpyruvate carboxykinase (PEPCK), hexokinase, phosphofructokinase, fructose-1,6-diphos-phatase, malate dehydrogenase, malic enzyme, and lactate dehydrogenase were measured. Renal glutaminase I activity rose during ketoacidosis and ammonium chloride acidosis. Glutamate dehydrogenase in the kidney rose only in ammonium chloride treated animals. Glutamine synthetase showed no particular variation. PEPCK rose in diabetic hyperglycemic animals and more so during ketoacidosis and ammonium chloride acidosis. It also rose in the liver of the diabetic animals. Hexokinase activity in the kidney rose in diabetic insulin-treated normoglycemic rats and also during ketoacidosis. The same pattern was observed in the liver of these diabetic rats. Renal and hepatic phosphofructokinase activities were elevated in all groups of experimental animals. Fructose-1,6-diphosphatase and malate dehydrogenase did not vary significantly in the kidney and the liver. Malic enzyme was lower in the kidney and liver of the hyperglycemic diabetic animals and also in the liver of the ketoacidotic rats. Lactate dehydrogenase fell slightly in the liver of diabetic hyperglycemic and NH4Cl acidotic animals. The present study indicates that glutaminase I is associated with the first step of increased renal ammoniagenesis during ketoacidosis. PEPCK activity is influenced both by hyperglycemia and ketoacidosis, acidosis playing an additional role. Insulin appears to prevent renal gluconeogenesis and to favour glycolysis. The latter would seem to remain operative in hyperglycemic and ketoacidotic diabetic animals.

Regulation of phosphoenolpyruvate carboxykinase and pyruvate kinase in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources and the role of mitochondrial function on gluconeogenesis

1986 ◽  
Vol 32 (12) ◽  
pp. 969-972 ◽  
Author(s):  
Albert J. Wilson ◽  
J. K. Bhattacharjee
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pyruvate Kinase ◽  
Growth Medium ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Carbon Sources ◽  
Absolute Requirement ◽  
Fructose 1,6 Bisphosphatase ◽  
Futile Cycling ◽  
Respiratory Deficient

Phosphoenolpyruvate carboxykinase (PEPCKase) and pyruvate kinase (PKase) were measured in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources. The PEPCKase activity was highest in ethanol-grown cells. However, high PEPCKase activity was also observed in cells grown in 1% glucose, especially as compared with the activity of sucrose-, maltose-, or galactose-grown cells. Activity was first detected after 12 h when glucose was exhausted from the growth medium. The PKase activity was very high in glucose-grown cells; considerable activity was also present in ethanol- and pyruvate-grown cells. The absolute requirement of respiration for gluconeogenesis was demonstrated by the absence or significantly low levels of PEPCKase and fructose-1,6-bisphosphatase activities observed in respiratory deficient mutants, as well as in wild-type S. cerevisiae cells grown in the presence of glucose and antimycin A or chloramphenicol. Obligate glycolytic and gluconeogenic enzymes were present sumultaneously only in stationary phase cells, but not in exponential phase cells; hence futile cycling could not occur in log phase cells regardless of the presence of carbon source in the growth medium.

scholarly journals Physiological concentrations of 2-oxoglutarate regulate the activity of phosphoenolpyruvate carboxykinase in liver

1992 ◽  
Vol 285 (3) ◽  
pp. 767-771 ◽  
Author(s):  
M A Titheradge ◽  
R A Picking ◽  
R C Haynes
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Rat Hepatocytes ◽  
Fasted State ◽  
Stimulation Of

2-Oxoglutarate was found to inhibit purified rat liver phosphoenolpyruvate carboxykinase when the assay was performed in the direction of either phosphoenolpyruvate or oxaloacetate synthesis. The inhibition was competitive with respect to oxaloacetate or phosphoenolpyruvate, the Ki values being 0.32 +/- 0.04 mM 0.63 +/- 0.19 mM respectively. 2-Oxoglutarate inhibited non-competitively when tested against GTP or Mn2+. The reported cytosolic concentrations of 2-oxoglutarate in rat hepatocytes are such that the enzyme is likely to be significantly inhibited under basal conditions. The cytosolic concentration of 2-oxoglutarate is known to fall precipitously under the influence of glucagon and other hormones that stimulate gluconeogenesis, and it is suggested that the hormone-induced decrease in 2-oxoglutarate content would alleviate the inhibition of phosphoenolpyruvate carboxykinase and stimulate flux from oxaloacetate to phosphoenolpyruvate. The implications of this finding to the rationalization of the role of pyruvate kinase in the stimulation of gluconeogenesis in the fasted state are discussed.

scholarly journals Effects of chronic hyperinsulinaemia on hepatic enzymes involved in lipogenesis and carbohydrate metabolism in the young rat

1978 ◽  
Vol 172 (2) ◽  
pp. 327-331 ◽  
Author(s):  
K L McCormick ◽  
J A Widness ◽  
J B Susa ◽  
R Schwartz
Keyword(s):  
Pyruvate Kinase ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Liver Weight ◽  
Hepatic Enzymes ◽  
Lower Blood Glucose ◽  
Lower Blood ◽  
Cleavage Enzyme ◽  
Young Rat ◽  
Blood Glucose Concentrations

Chronic (6 days) hyperinsulinaemia in young rats produced lower blood glucose concentrations and augmented body- and liver-weight gain. The insulin-treated rats had increased hepatic activities of citrate-cleavage enzyme, ‘malic’ enzyme and high-substrate (6.6 mM-phosphoenolpyruvate) pyruvate kinase, and decreased glucose 6-phosphatase. There were no changes in activities of phosphoenolpyruvate carboxykinase, phosphofructokinase, low-substrate (1.3 mM-phosphoenolpyruvate) pyruvate kinase, glucokinase and hexokinase.

scholarly journals Phosphoenolpyruvate Carboxykinase Is Necessary for the Integration of Hepatic Energy Metabolism

2000 ◽  
Vol 20 (17) ◽  
pp. 6508-6517 ◽  
Author(s):  
Pengxiang She ◽  
Masakazu Shiota ◽  
Kathy D. Shelton ◽  
Roger Chalkley ◽  
Catherine Postic ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Intermediary Metabolites ◽  
Hepatic Energy Metabolism ◽  
Genes Encoding ◽  
Plasma Hormone ◽  
Hepatic Genes ◽  
Targeting Strategy ◽  
Global Reduction

ABSTRACT We used an allelogenic Cre/loxP gene targeting strategy in mice to determine the role of cytosolic phosphoenolpyruvate carboxykinase (PEPCK) in hepatic energy metabolism. Mice that lack this enzyme die within 3 days of birth, while mice with at least a 90% global reduction of PEPCK, or a liver-specific knockout of PEPCK, are viable. Surprisingly, in both cases these animals remain euglycemic after a 24-h fast. However, mice without hepatic PEPCK develop hepatic steatosis after fasting despite up-regulation of a variety of genes encoding free fatty acid-oxidizing enzymes. Also, marked alterations in the expression of hepatic genes involved in energy metabolism occur in the absence of any changes in plasma hormone concentrations. Given that a ninefold elevation of the hepatic malate concentration occurs in the liver-specific PEPCK knockout mice, we suggest that one or more intermediary metabolites may directly regulate expression of the affected genes. Thus, hepatic PEPCK may function more as an integrator of hepatic energy metabolism than as a determinant of gluconeogenesis.

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