scholarly journals Synthesis and degradation of phosphoenolpyruvate carboxylase in rat liver and adipose tissue. Changes during a starvation–re-feeding cycle

1973 ◽  
Vol 134 (2) ◽  
pp. 445-453 ◽  
Author(s):  
M. F. Hopgood ◽  
F. J. Ballard ◽  
Lea Reshef ◽  
R. W. Hanson
Keyword(s):  
Adipose Tissue ◽  
Total Synthesis ◽  
Phosphoenolpyruvate Carboxylase ◽  
Degradation Rate ◽  
Relative Rate ◽  
Enzyme Synthesis ◽  
Starvation Period ◽  
Feeding Cycle ◽  
Tissue Changes ◽  
Synthesis And Degradation

A specific antibody against liver cytosol phosphoenolpyruvate carboxylase (EC 4.1.1.32) was used to isolate the enzyme from liver and adipose tissue. With this technique we have shown that phosphoenolpyruvate carboxylase synthesis in starved rats accounts for 3% of the total synthesis of cytosol protein in each tissue. Re-feeding starved animals decreases this relative rate of phosphoenolpyruvate carboxylase synthesis to 0.2% and 1% respectively in liver and adipose tissue, and the activity of the enzyme in each tissue is decreased to 25% of the starvation value. An additional starvation period is accompanied by an increased rate of enzyme synthesis, but the response to starvation is considerably slower than that caused by re-feeding. The degradation rate of phosphoenolpyruvate carboxylase is also subject to regulation. Thus re-feeding starved animals decreases the half-life of the enzyme in liver from 13h to 5.2h, but the rapid rate of degradation is maintained at least during the first 20h of subsequent starvation. Only slight changes in the degradation rate of phosphoenolpyruvate carboxylase are found in adipose tissue. We conclude that the large alterations in the rate of enzyme synthesis during a starvation–re-feeding cycle are the major cause of fluctuations in activity.

scholarly journals Phosphopyruvate carboxylase induction by l-tryptophan. Effects on synthesis and degradation of the enzyme

1973 ◽  
Vol 136 (2) ◽  
pp. 259-264 ◽  
Author(s):  
F. J. Ballard ◽  
M. F. Hopgood
Keyword(s):  
Enzyme Activity ◽  
Specific Antibody ◽  
Actinomycin D ◽  
Relative Rate ◽  
Enzyme Synthesis ◽  
Enzyme Protein ◽  
Carboxylase Activity ◽  
Twofold Increase ◽  
Synthesis And Degradation

1. The administration of l-tryptophan to fed rats produces a twofold increase in hepatic phosphopyruvate carboxylase activity that represents a comparable increase in enzyme protein. With specific antibody against the enzyme we have shown that the increase in phosphopyruvate carboxylase is partially mediated via an actinomycin D-sensitive increase in enzyme synthesis. 2. In starved animals tryptophan increases the enzyme activity without any change in the relative rate of phosphopyruvate carboxylase synthesis. In this condition degradation of the enzyme is retarded by tryptophan by a mechanism that is not prevented by cycloheximide.

Refeeding and insulin increase lipoprotein lipase activity in rat brown adipose tissue

1989 ◽  
Vol 256 (5) ◽  
pp. E645-E650 ◽  
Author(s):  
C. M. Carneheim ◽  
S. E. Alexson
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Starvation Period ◽  
Lipoprotein Lipase Activity ◽  
Mrna Synthesis ◽  
Beta Adrenergic ◽  
Brown Adipose

Induction of lipoprotein lipase activity in brown adipose tissue (BAT) in response to cold stress has earlier been shown to be regulated by a beta-adrenergic mechanism and to be dependent on mRNA synthesis. In the present study, we have investigated the acute effects of refeeding after a short starvation period and the hormonal mechanism underlying the observed effects. Refeeding was found to rapidly increase tissue wet weight and lipoprotein lipase activity. The increase in enzyme activity could be blocked by the RNA synthesis inhibitor actinomycin D, indicating a gene activation. beta-Adrenergic blockade had no effect on this elevation of enzyme activity, but the increase could be mimicked by insulin injection. The results suggest that BAT contains two different pathways for regulation of lipoprotein lipase activity, both involving mRNA synthesis.

Comparison of adipose tissue changes following administration of rosiglitazone in the dog and rat

2001 ◽  
Vol 3 (3) ◽  
pp. 163-170 ◽  
Author(s):  
C. D. N. Toseland ◽  
S. Campbell ◽  
I. Francis ◽  
P. J. Bugelski ◽  
N. Mehdi
Keyword(s):  
Adipose Tissue ◽  
Tissue Changes

Total Synthesis of Tiacumicin A. Total Synthesis, Relay Synthesis, and Degradation Studies of Fidaxomicin (Tiacumicin B, Lipiarmycin A3)

2018 ◽  
Vol 83 (13) ◽  
pp. 7180-7205 ◽  
Author(s):  
Hiromu Hattori ◽  
Elias Kaufmann ◽  
Hideki Miyatake-Ondozabal ◽  
Regina Berg ◽  
Karl Gademann
Keyword(s):  
Total Synthesis ◽  
Degradation Studies ◽  
Synthesis And Degradation

scholarly journals Nutritional and hormonal regulation of malic enzyme synthesis in rat mammary gland

1986 ◽  
Vol 236 (2) ◽  
pp. 441-445 ◽  
Author(s):  
M F Lobato ◽  
M Ros ◽  
F J Moreno ◽  
J P García-Ruíz
Keyword(s):  
Enzyme Activity ◽  
Mammary Gland ◽  
Malic Enzyme ◽  
Hormonal Regulation ◽  
Relative Rate ◽  
Enzyme Synthesis ◽  
Soluble Proteins ◽  
Control Value ◽  
Rat Mammary Gland ◽  
Malic Enzyme Activity

Cytosolic malic enzyme was purified from rat mammary gland by L-malate affinity chromatography. The pure enzyme obtained was used to produce a specific antiserum in a rabbit. Relative synthesis of malic enzyme in the mammary gland of mid-lactating rats was 0.097%, measured by labelling the enzyme in isolated acini. When food was removed, malic enzyme synthesis decreased to 35% and 20% of the control value at 4 and 6 h respectively. Incorporation of [3H]leucine into soluble proteins was constant during the first 6 h of starvation. When lactating rats (maintained with their pups) were starved for 24 h and then re-fed, the relative rate of enzyme synthesis increased 2.5-, 4-, and 4.5-fold at 3 h, 6 h and 18 h respectively after initiation of re-feeding. The relative rate of malic enzyme synthesis was about 50% of normal at 15 h after weaning, whereas the rate of synthesis of soluble proteins did not change. Administration of bromocriptine or adrenalectomy of lactating rats decreased the relative rate of synthesis of malic enzyme by 40% or 30% respectively; these effects were counteracted by hormone supplementation. Hormone therapy also caused an increase in the rate of incorporation of [3H]leucine into soluble proteins and in malic enzyme activity.

scholarly journals The effect of insulin and glucocorticoids on the synthesis and degradation of phosphoenolpyruvate carboxykinase (GTP) in rat adipose tissue cultured in vitro

1976 ◽  
Vol 158 (1) ◽  
pp. 9-16 ◽  
Author(s):  
O Meyuhas ◽  
L Reshef ◽  
F J Ballard ◽  
R W Hanson
Keyword(s):  
Protein Synthesis ◽  
Adipose Tissue ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Epididymal Adipose Tissue ◽  
Large Size ◽  
A Value ◽  
Rat Adipose Tissue ◽  
Synthesis And Degradation

1. Epididymal adipose tissue from the rat was maintained in culture for periods of up to 96h. 2. After an initial decrease in protein synthesis during the first 24h of culture, the adipose tissue recovered its capacity to synthesize and accumulate proteins of a relatively large size. 3. The activity of phosphoenolpyruvate carboxykinase decreased in a parallel manner, but increased again after 24h of incubation of the tissue in culture, to a value twice that noted in the tissue in vivo. This increase in enzyme activity was due to an increase in its rate of synthesis. 4. Both insulin and dexamethasone (9alpha-fluoro-16alpha-methyl-11beta,17,-21-trihydroxypregna-1,4-diene-3,20-dione) inhibited phosphoenolpyruvate carboxykinase synthesis, but dexamethasone also decreased total protein synthesis. 5. The half-life of phosphoenolpyruvate carboxykinase in adipose tissue cultured in vitro was 5-7h and was not altered by insulin or dexamethasone. 6. It is concluded that both insulin and glucocroticoids lower the activity of phosphoenolpyruvate carboxykinase in rat adipose tissue by decreasing its rate of synthesis.

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