scholarly journals Depletion of glycogen synthetase and increase of glucose 6-phosphate dehydrogenase in livers of ethionine-treated mice

1965 ◽  
Vol 97 (1) ◽  
pp. 32-36 ◽  
Author(s):  
HG Sie ◽  
A Hablanian
Keyword(s):  
Pyruvate Kinase ◽  
Glucose Dehydrogenase ◽  
Liver Glycogen ◽  
Synthetase Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Glycogen Synthetase ◽  
Glucose 6 Phosphate Dehydrogenase

1. Ethionine-treated mice showed a marked depletion in liver glycogen, a decrease of glycogen-synthetase activity, an increase in activity of glucose 6-phosphate dehydrogenase and the solubilization of phosphorylase. 2. The administration of cortisol or glucose did not alleviate these changes but the effect of ethionine was completely prevented in animals given methionine as well as ethionine. 3. The activities of the following enzymes were unchanged: hexokinase, glucokinase, glucose 6-phosphatase, phosphoglucomutase, 6-phosphogluconate dehydrogenase, UDP-glucose pyrophosphorylase, UDP-glucose dehydrogenase and pyruvate kinase.

scholarly journals Stimulation of pentose phosphate pathway dehydrogenase enzyme activities in ethionine-treated mice

1968 ◽  
Vol 106 (4) ◽  
pp. 769-776 ◽  
Author(s):  
Hsien-Gieh Sie ◽  
William H. Fishman
Keyword(s):  
Dehydrogenase Activity ◽  
Fold Increase ◽  
Pentose Phosphate ◽  
Hepatic Glycogen ◽  
Synthetase Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Glycogen Synthetase ◽  
Period 2 ◽  
Marked Preference ◽  
Glucose 6 Phosphate Dehydrogenase

1. Mice treated with ethionine (intraperitoneally, 5mg./day for 4 days or 10mg./day for 3 days) showed a profound loss of hepatic glycogen, a decrease of glycogen synthetase activity, a development of hypoglycaemia, a two- to five-fold increase in the activity of glucose 6-phosphate dehydrogenase but no change in 6-phosphogluconate dehydrogenase and an earlier manifestation of the solubilization of phosphorylase as compared with glycogen synthetase. The administration of ATP did not prevent these effects. 2. During the early post-injection period (2–3 days) there was a further enhancement of the activity of glucose 6-phosphate dehydrogenase (tenfold) in the liver and a clear elevation of 6-phosphogluconate dehydrogenase activity (twofold). Subsequently, the glycogen concentration was restored, followed by an earlier reassociation of glycogen particle with phosphorylase than with glycogen synthetase, along with a disappearance of ethionine effect at about the eighteenth day. 3. Glucose 6-phosphate dehydrogenase from both control and ethionine-treated animals showed a marked preference for glucose 6-phosphate as substrate rather than for galactose 6-phosphate, whose rate of oxidation was only 10% of that of the glucose 6-phosphate. 4. Since actinomycin D, puromycin, 5-fluorouracil and dl-p-fluorophenylalanine failed to block the ethionine-enhanced glucose 6-phosphate dehydrogenase activity, the possibility that new enzyme protein synthesis is responsible for the effect is doubtful.

scholarly journals Degradation of glucose-metabolizing enzymes in the rat small intestine during starvation

1973 ◽  
Vol 132 (4) ◽  
pp. 657-661 ◽  
Author(s):  
Gwyneth M. Jones ◽  
R. J. Mayer
Keyword(s):  
Small Intestine ◽  
Lactate Dehydrogenase ◽  
Pyruvate Kinase ◽  
Phosphoglycerate Kinase ◽  
Rat Small Intestine ◽  
Metabolizing Enzymes ◽  
Phosphogluconate Dehydrogenase ◽  
Degradation Rates ◽  
Glucose 6 Phosphate Dehydrogenase

1. The degradation rates and half-lives of hexokinase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase, pyruvate kinase, glucose 6-phosphate dehydrogenase, phosphoglycerate kinase and aldolase were calculated from measurements of the decline in activities of these enzymes in rat small intestine during starvation. 2. The half-lives of the enzymes are: hexokinase, 5.7h; 6-phosphogluconate dehydrogenase, 7.6h; glucose 6-phosphate dehydrogenase, 6.0h; pyruvate kinase, 8.9h; lactate dehydrogenase, 8.7h; phosphoglycerate kinase, 8.7h; aldolase, 5.1h. 3. The significance of the results is discussed with respect to the regulation of enzyme concentrations in response to changes in diet.

scholarly journals The transport of oxidized glutathione from the erythrocytes of various species in the prescence of chromate

1969 ◽  
Vol 114 (4) ◽  
pp. 833-837 ◽  
Author(s):  
Satish K. Srivastava ◽  
Ernest Beutler
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Reductase ◽  
Pyruvate Kinase ◽  
Transport Rate ◽  
Oxidized Glutathione ◽  
Phosphogluconate Dehydrogenase ◽  
Presence And Absence ◽  
Glucose 6 Phosphate Dehydrogenase

1. Erythrocytes from normal and glucose 6-phosphate dehydrogenase-deficient humans were subjected to hydrogen peroxide diffusion to oxidize the GSH. Studies were carried out in the presence and absence of chromate to inhibit glutathione reductase and with or without the addition of glucose. 2. The GSH content of erythrocytes from other species was oxidized by subjecting them to hydrogen peroxide diffusion in the presence of chromate and glucose. 3. Chromate (1·3mm) inhibited glutathione reductase by about 80%, whereas glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase and pyruvate kinase were not inhibited. 4. The GSSG formed was transported from the erythrocytes to the medium. 5. The transport rate of GSSG from glucose 6-phosphate dehydrogenase-deficient erythrocytes subjected to hydrogen peroxide diffusion in the presence of chromate was comparable with that from normal and glucose 6-phosphate dehydrogenase-deficient erythrocytes. 6. The rate of transport of GSSG from erythrocytes of various species studied could be ranked: pigeon>rabbit>rat>donkey>man>dog>horse>sheep>chicken>fish.

Utilization of native primer by mammalian liver glycogen synthetase: primer efficiency in binding the enzyme and in catalysis

1968 ◽  
Vol 46 (6) ◽  
pp. 579-586 ◽  
Author(s):  
A. Vardanis
Keyword(s):  
Low Temperatures ◽  
Liver Glycogen ◽  
Catalytic Site ◽  
Lower Amount ◽  
Synthetase Activity ◽  
Substrate Complex ◽  
Glycogen Synthetase ◽  
Enzyme Substrate ◽  
Dependent Activity ◽  
Mammalian Liver

The particulate glycogen–glycogen synthetase complex isolated from mammalian liver is often strongly dependent on the addition of primer for activity. The present experiments offer an explanation for this behavior. Hepatic α-amylase, which is also adsorbed on the particle, can, even at the low temperatures (0–4°) of the preparatory procedure, hydrolyze the outer branches of particulate glycogen and thus reduce its efficiency as a primer. Synthetase activity of particulate glycogen prepared from the livers of starved animals is much more dependent on the addition of exogenous primer as compared to the enzyme from fed animals. Correspondingly, the livers of starved animals contain a lower amount of particulate glycogen and exhibit higher α-amylase activity.When particulate glycogen is rapidly prepared from fed animals, the glucose-6-P independent portion of its glycogen synthetase activity is only slightly increased by addition of extra primer. The glucose-6-P dependent activity of the same preparations, however, is doubled by addition of soluble glycogen, suggesting that the latter form of the synthetase is bound to glycogen in a partially inactive complex.The efficiency of a glycogen sample in binding the synthetase seems to be proportional to the ability of that sample to act as primer in the synthetase reaction. This finding strengthens the hypothesis that the enzyme is adsorbed to glycogen through its catalytic site, i.e. in an enzyme–substrate complex. It is evident, however, that in a number of cases this complex is only partially active since it exhibits varying degrees of dependence on added soluble primer.

Effects of Adrenalectomy, Adrenalectomy–Ovariectomy, and Cortisol and Estrogen Therapies Upon Enzyme Activities in Lactating Rat Mammary Glands

1972 ◽  
Vol 50 (4) ◽  
pp. 366-376 ◽  
Author(s):  
G. O. Korsrud ◽  
R. L. Baldwin
Keyword(s):  
Pyruvate Kinase ◽  
Enzyme Activities ◽  
Secretory Cell ◽  
Succinic Dehydrogenase ◽  
Mammary Glands ◽  
Pentose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Udpglucose Pyrophosphorylase ◽  
Cleavage Enzyme ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of adrenalectomy and adrenalectomy–ovariectomy on the 5th day of lactation followed by cortisol and estrogen therapies on enzyme activities in rat mammary glands were investigated. This stage of lactation was selected because mammary secretory cell proliferation is essentially complete at this time thereby enabling study of the effects of cortisol and estrogen on enzyme levels in a nonproliferating secretory cell population. Eighteen enzymes were selected for study on the bases of their respective roles in milk biosynthesis and carbohydrate and energy metabolism and/or on the basis of previous studies indicating that their activities increase during midlactation or are regulated, in part, by steroid hormones. After adrenalectomy on the 5th day of lactation, cortisol therapy was required for normal increases in the activities of succinic dehydrogenase, citrate cleavage enzyme, malic enzyme, UDPglucose pyrophosphorylase, UDPglucose 4-epimerase, and glucose-6-phosphate dehydrogenase. The activities of UDPglucose pyrophosphorylase and glucose-6-phosphate dehydrogenase were higher than normal in cortisol-treated animals. Cortisol therapy during the last 2 days of the experiment increased the activity of UDPglucose pyrophosphorylase and possibly citrate cleavage enzyme. The activities of α-glycerolphosphate dehydrogenase, phosphoglucomutase, 6-phosphogluconate dehydrogenase, pentose phosphate metabolizing ability, hexokinase, phosphofructokinase, fructose-1,6-diphosphate aldolase, pyruvate kinase, lactic dehydrogenase, aspartate aminotransferase, isocitrate dehydrogenase, and extramitochondrial malate dehydrogenase were not notably affected by adrenalectomy or cortisol therapy. The activities of 6-phosphogluconate dehydrogenase, pentose phosphate metabolizing ability, phosphofructokinase, and pyruvate kinase may have increased after the 5th day of lactation in adrenalectomized as well as in normal animals. Combining ovariectomy with adrenalectomy reduced pup weight gains more than adrenalectomy alone, but did not further decrease significantly the activities of any of the enzymes measured. Ovariectomy had no effect when cortisol was administered. Cortisol therapy completely reversed adverse effects of estrogen given to adrenalectomized–ovariectomized animals. On the bases of these and previous data, it was concluded that cortisol regulates the rates of synthesis of several mammary gland enzymes during midlactation.

Time-course of enzyme adaptation. I. Effects of substituting dietary glucose and fructose at constant concentrations of dietary protein

1968 ◽  
Vol 46 (12) ◽  
pp. 1459-1470 ◽  
Author(s):  
B. Szepesi ◽  
R. A. Freedland
Keyword(s):  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
Dietary Protein ◽  
Malic Enzyme ◽  
Dietary Change ◽  
Phosphogluconate Dehydrogenase ◽  
Dietary Fructose ◽  
Liver And Kidney ◽  
Malic Enzyme Activity ◽  
Glucose 6 Phosphate Dehydrogenase

The effect of dietary fructose on liver, kidney, and adrenal enzymes was studied in male Sprague–Dawley rats. Dietary fructose increased relative liver and kidney sizes, liver glycogen, and liver protein. The percentage increases in relative liver and kidney sizes were independent of dietary protein, but relative liver sizes were smaller in the absence of protein.The activities of all the liver enzymes studied, except glucokinase, were increased by a 65% fructose diet containing 25% casein. The rates of increases differed between enzymes; the activities of L-α-glycerophosphate dehydrogenase and phosphoenolpyruvate carboxykinase (PEP-carboxykinase) reached almost maximum in 1 day, glucose 6-phosphatase, 6-phosphogluconate dehydrogenase, and pyruvate kinase activities reached maximum in about 2 days, and glucose 6-phosphate dehydrogenase, malic enzyme, dihydroxyacetone kinase, phosphofructose kinase, and phosphohexose isomerase required at least 3 days to reach maximum activity after the dietary change. The increases in the activities of liver fructose 1,6-diphosphatase, glucose 6-phosphate dehydrogenase, pyruvate kinase, and phosphohexose isomerase did not occur in the absence of dietary protein. The activities of liver phosphofructokinase and malic enzyme were increased equally well whether the fructose diet contained protein or not, while the increases in the activities of other enzymes were less in the absence of dietary protein.The half-life of liver malic enzyme was estimated as 3 days in the glucose to fructose dietary change and 1 day in the fructose to glucose dietary change. Since malic enzyme activity was increased by fructose feeding about threefold, the data suggest that under the conditions of the experiment fructose increased malic enzyme activity by decreasing the rate of breakdown of the enzyme.In general, kidney enzymes were affected by fructose to a lesser extent than the corresponding enzymes in liver. This was particularly significant in the case of kidney glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malic enzyme, the activities of which were only slightly increased in kidney. The activities of these three enzymes in the adrenal glands were not increased by fructose feeding.

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