Enzymes Involved in Fructose Metabolism in Liver and the Glyceraldehyde Metabolic Crossroads

Sillero, Marı́a A. Günther; Sillero, Antonio; Sols, Alberto

doi:10.1111/j.1432-1033.1969.tb00696.x

Cited by 126 publications

(61 citation statements)

References 38 publications

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“…Attempts were made to determine the distribution of aldolases A and B (Rutter et al, 1963) in mouse liver, by using the kinetic method of Sillero et al (1969) with fructose 1,6-diphosphate and fructose 1-phosphate as the respective substrates. Whole liver homogenate, however, exhibits a ratio of fructose 1,6-diphosphate aldolase to fructose 1-phosphate aldolase activities of only 0.94 (Table 6).…”

Section: Activities Of Cytoplasmic Enzymesmentioning

confidence: 99%

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Crisp

Pogson

1972

Biochemical Journal

130

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Parenchymal cells contain both glucose 6-phosphatase and fructose 1,6-diphosphatase. The non-parenchymal fraction appears to contain fructose 1,6-diphosphatase, but is devoid of glucose 6-phosphatase. 8. No aldolase A was detectable in the whole liver. Aldolase B occurs in both parenchymal and non-parenchymal tissue. 9. Parenchymal cells prepared by mechanical disruption ofmouse liver with 20 % polyvinyl alcohol exhibit a similar enzyme profile to those prepared enzymically. 10. The methodology involved in the preparation of isolated liver cells is discussed. The importance of the measurement of several parameters as criteria for establishing the viability of parenchymal cells is stressed. 11. The metabolic implications of the results in the present study are discussed.

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Section: Activities Of Cytoplasmic Enzymesmentioning

confidence: 99%

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Crisp

Pogson

1972

Biochemical Journal

130

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“…After the finding of the induction of glucokinase in rat liver by insulin, Weber et al [S] postulated the hypothesis that the key steps of glycolysis and gluconeogenesis could depend on two functional genic units, with insulin as inducer of the glycolytic unit and repressor of the gluconeogenic one. Shortly afterwards a number of observations were reported on the behaviour of pyruvate kinase [9- glycerol, both triosephosphate prccursors that by-pass glucokinase and phosphofructokinase [13]. With this approach, non-coordinated variations in the activity of enzymes which catalyze physiologically irreversible steps of glycolysis and gluconeogenesis in liver have been observed in normal and diabetic rats.…”

mentioning

confidence: 99%

Regulation of the Level of Key Enzymes of Glycolysis and Gluconeogenesis in Liver

Sillero¹,

Sillero²,

Sols³

1969

European Journal of Biochemistry

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Diets rich in fructose, glycerol, or both were fed to normal and diabetic rats, and the activities of enzymes which catalyze irreversible steps of glycolysis and gluconeogenesis were studied in liver. With these diets, rich in precursors of triosephosphates, the activities of glucose-6-phosphatase and pyruvate kinase in liver were high, while those of glucokinase and phosphoenolpyruvate carboxykinase were low. A metabolic bifurcation to glycolysis and gluconeogenesis, below and above the trioscphosphates level respectively, has then been shown to be easily maintained in liver.It is suggested that the induction of glucokinase and pyruvate kinase in diabetic animals after insulin administration is a sequential process that involves hormonal induction of glucokinase by insulin and secondary metabolite induction of the L isoenzyme of pyruvate kinase by some glycolytic intermediate. The occurrence of independent mechanisms for the regulation in liver of the activity of enzymes which catalyze irreversible steps of glycolysis and gluconeogenesis affords a valuable metabolic plasticity.Changes in the apparent concentration of a number of enzymes in liver have been observed in relation to the nutritional and hormonal conditions of the animal. Some of these changes could be of considerable significance in the regulation of major metabolic pathways. Glucose-6-phosphatase [l] glycerol, both triosephosphate prccursors that by-pass glucokinase and phosphofructokinase [13]. With this approach, non-coordinated variations in the activity of enzymes which catalyze physiologically irreversible steps of glycolysis and gluconeogenesis in liver have been observed in normal and diabetic rats. A preliminary report of this finding has already appeared [14]. MATERIALS AND METHODSWhite rats weighing 140-2OOg were used. Animals were made diabetic with alloxan (intravenously, 40 mg/kg body weight) ; treated animals were considered diabetic when the glucosuria reached values of at least 0.5 g/100 ml.Control rats were fed a stock diet ad libitum. The composition of the fructose, glycerol, and fructoseglycerol diets utilized was: 30°/, casein, 5O/, fat, and 5 0 / , cellulose, supplemented with minerals and vitamins, and 600/, fructose, or 60°/, glycerol, or 30°/, fructose and 30°/, glycerol, respectively. Groups of animals were maintained on these diets for 3 to 5 days. They ate the fructose and the fructoseglycerol diets well, but the glycerol diet not so well. The rats were killed by decapitation. The livers were excised and homogenized with two volumes-of 0.1 M Tris pH 7.2-1 mM EDTA-1 mM ethanethiol in a Kontes-Dual1 Grinder. The homogenates were centrifuged at 3000Oxg for 20 min. All operations were

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“…During fasting, the activity of the enzyme rapidly declines, while refeeding of a carbohydrate-rich diet restores the enzyme activity (9)(10)(11)(12)(13)(14)(15).…”

Section: Introductionmentioning

confidence: 99%

“…In both liver and small intestine, aldolase B activity (i.e., the activity toward the substrate FIP) fluctuates according to dietary status (9)(10)(11)(12)(13)(14)(15). During fasting, the activity of the enzyme rapidly declines, while refeeding of a carbohydrate-rich diet restores the enzyme activity (9)(10)(11)(12)(13)(14)(15).…”

Section: Introductionmentioning

confidence: 99%

Dietary and hormonal regulation of aldolase B gene expression.

Münnich¹,

Besmond²,

Darquy³

et al. 1985

J. Clin. Invest.

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Aldolase B is an enzyme of the glycolytic pathway whose activity and mRNA levels in the liver fluctuate according to dietary status. Both the enzyme activity and the mRNA concentration decline during fasting and increase four-to eightfold upon refeeding of a carbohydrate-rich diet. The mechanism, however, of the mRNA induction remains unknown.To elucidate the mechanisms that regulate this induction responsive to dietary stimuli, we have studied the roles of hormones and glycolytic substrates on aldolase B gene expression in three tissues that synthesize the enzyme. Using a cDNA probe complementary to rat aldolase B mRNA, we determined the amount of cytoplasmic RNAs in the liver, kidney, and small intestine of normal, adrenalectomized, thyroidectomized, diabetic, and glucagon-or cAMP-treated animals refed either a fructose-rich or a maltose-rich diet. The in vivo hormonal control of gene expression was found to be very different in the three organs tested. In the liver, cortisone and thyroid hormones were required for the induction of the specific mRNA by carbohydrates, while in the kidney none of the hormonal modifications tested altered the level of mRNA induction. In the liver, but not in the kidney, diabetes and glucagon administration abolished the induction of aldolase B mRNAs in animals refed the maltose-rich diets. In the small intestine, only diabetes and thyroidectomy affected the gene expression. Finally, no induction occurred when normal fasted rats were given any of the hormones.Thus, the in vivo hormonal control of liver aldolase B gene expression differs significantly from that of kidney and small intestine. In the liver, the mRNA induction requires the presence of dietary carbohydrates, of permissive hormones, and the cessation of glucagon release, while in the kidney, the induction of the mRNAs by fructose occurs regardless of the hormonal status of the animals. The hormonal control of aldolase B mRNA levels in the small intestine is intermediate.

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Enzymes Involved in Fructose Metabolism in Liver and the Glyceraldehyde Metabolic Crossroads

Cited by 126 publications

References 38 publications

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Regulation of the Level of Key Enzymes of Glycolysis and Gluconeogenesis in Liver

Dietary and hormonal regulation of aldolase B gene expression.

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