scholarly journals Studies on the assay, activity and sedimentation behaviour of acetyl-CoA carboxylase from isolated hepatocytes incubated with insulin or glucagon

1984 ◽  
Vol 221 (3) ◽  
pp. 869-874 ◽  
Author(s):  
K F Buechler ◽  
A C Beynen ◽  
M J H Geelen
Keyword(s):  
Enzyme Activity ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Cell Extracts ◽  
Malonyl Coa ◽  
Triton X ◽  
Acid Stable

The activity of acetyl-CoA carboxylase, measured in various ways, was studied in 15000g extracts of rat liver hepatocytes and compared with the rate of fatty acid synthesis in intact hepatocytes incubated with insulin or glucagon. Hepatocyte extracts were prepared by disruption of cells with a Dounce homogenizer or by solubilization with 1.5% (v/v) Triton X-100. Sucrose-density-gradient centrifugation demonstrated that the sedimentation coefficient of acetyl-CoA carboxylase from cell extracts was 30-35S, regardless of the conditions of incubation or disruption of hepatocytes. Solubilization of cells with 1.5% Triton X-100 yielded twice as much enzyme activity (measured by [14C]bicarbonate fixation) in the sucrose-gradient fractions as did cell disruption by the Dounce homogenizer. Analysis by high-performance liquid chromatography of acetyl-CoA carboxylase reaction mixtures showed that [14C]malonyl-CoA accounted for 10-60% of the total acid-stable radioactivity, depending on the method for disrupting hepatocytes and on the preincubation of the 15000g extract, with or without citrate, before assay. Under conditions in which incubation of cells with insulin or glucagon caused an activation or inhibition, respectively, of acetyl-CoA carboxylase, only 25% of the acid-stable radioactivity was [14C]malonyl-CoA and enzyme activity was only 13% (control), 16% (insulin), and 57% (glucagon) of the rate of fatty acid synthesis. Under conditions when up to 60% of the acid-stable radioactivity was [14C]malonyl-CoA and acetyl-CoA carboxylase activity was comparable with the rate of fatty acid synthesis, there was no effect of insulin or glucagon on enzyme activity.

scholarly journals Regulation of fatty acid synthesis and malonyl-CoA content in mouse brown adipose tissue in response to cold-exposure, starvation or re-feeding

1987 ◽  
Vol 243 (2) ◽  
pp. 437-442 ◽  
Author(s):  
M G Buckley ◽  
E A Rath
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
Cold Exposure ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Malonyl Coa ◽  
Brown Adipose

1. The effect of nutritional status on fatty acid synthesis in brown adipose tissue was compared with the effect of cold-exposure. Fatty acid synthesis was measured in vivo by 3H2O incorporation into tissue lipids. The activities of acetyl-CoA carboxylase and fatty acid synthetase and the tissue concentrations of malonyl-CoA and citrate were assayed. 2. In brown adipose tissue of control mice, the tissue content of malonyl-CoA was 13 nmol/g wet wt., higher than values reported in other tissues. From the total tissue water content, the minimum possible concentration was estimated to be 30 microM 3. There were parallel changes in fatty acid synthesis, malonyl-CoA content and acetyl-CoA carboxylase activity in response to starvation and re-feeding. 4. There was no correlation between measured rates of fatty acid synthesis and malonyl-CoA content and acetyl-CoA carboxylase activity in acute cold-exposure. The results suggest there is simultaneous fatty acid synthesis and oxidation in brown adipose tissue of cold-exposed mice. This is probably effected not by decreases in the malonyl-CoA content, but by increases in the concentration of free long-chain fatty acyl-CoA or enhanced peroxisomal oxidation, allowing shorter-chain fatty acids to enter the mitochondria independent of carnitine acyltransferase (overt form) activity.

scholarly journals Medium-chain fatty acids as short-term regulators of hepatic lipogenesis

1994 ◽  
Vol 302 (1) ◽  
pp. 141-146 ◽  
Author(s):  
M J H Geelen
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Short Term ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Malonyl Coa ◽  
Stimulation Of

Short-term exposure of isolated rat hepatocytes to short- and medium-chain fatty acids led to an activation of acetyl-CoA carboxylase as measured in digitonin-permeabilized hepatocytes. Up to a certain concentration, typical for each of the fatty acids used, fatty acid-dependent activation of acetyl-CoA carboxylase coincided with an increase in the rate of fatty acid synthesis in intact hepatocytes, as determined by the incorporation of 3H from 3H2O water into fatty acids. At higher concentrations loss of stimulation of fatty acid synthesis occurred, but not the enhancement of carboxylase activity. With the fatty acids tested (C8:0-C14:0), the peak in fatty acid synthesis coincided with a peak in the level of malonyl-CoA. The onset of the stimulation of carboxylase activity coincided with the start of the peak in both fatty acid synthesis and malonyl-CoA. The longer the chain length of the fatty acid added, the lower the concentration at which the rate of fatty acid synthesis and the level of malonyl-CoA reached a peak and carboxylase activity started to become elevated. In cell suspensions incubated with increasing concentrations of fatty acids, accumulation of lactate decreased progressively. The latter observation, in combination with the fact that the activity of acetyl-CoA carboxylase is not always related to the rate of fatty acid biosynthesis, suggests that under these conditions not the activity of the carboxylase but the flux through the glycolytic sequence determines, at least in part, the rate of fatty acid synthesis de novo.

Regulation of Acetyl-Coenzyme A Carboxylase and Acetyl-Coenzyme A Synthetase in Spinach Chloroplasts

1984 ◽  
Vol 39 (3-4) ◽  
pp. 268-275 ◽  
Author(s):  
Andreas Sauer ◽  
Klaus-Peter Heise
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Coenzyme A ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Key Enzymes ◽  
Spinach Chloroplasts ◽  
Triton X

In analogy to chloroplast fatty acid synthesis from acetate the key enzymes of acetate fixation, acetyl-CoA synthetase and acetyl-CoA carboxylase, in rapidly Triton X-100 lysed spinach chloroplasts show an activation by light and deactivation in the dark. The stim ulation of acetyl-CoA carboxylase by dithiothreitol in darkened chloroplasts points to an involvement of reducing equivalents in the light activation of this enzyme. But more than by alterations of the activation state per se, these enzymes appear to be effected by changes in their catalytic activity due to differences in the proton-, Mg2+- and adenine nucleotide levels of the chloroplast stroma. Thus the pH dependence of both enzymes, as immediately extracted from Triton X-100 lysed chloroplasts, resembles that recently found for lipid incorporation of acetate into intact spinach chloroplasts in the light with an identical pH optim um of about pH 8.5 for the acetyl-CoA carboxylase. Moreover, in the same extracts both enzyme activities show the already postulated requirement for MgATP and free Mg and are com petitively inhibited by free ATP and ADP with respect to MgATP. But on account of the fact, that the extractable acetyl-CoA synthetase as opposed to the carboxylase activities exceed by far the lipid incorporation rates of acetate by illuminated chloroplasts before disruption, acetyl-CoA synthetase will be excluded as rate limiting step in fatty acid synthesis from acetate. From key enzymes of acetate fixation only the carboxylase appears to be involved therefore in the light regulation of acetate incorporation into long-chain fatty acids

The Classical, Yet Controversial, First Enzyme of Lipid Synthesis: Escherichia coli Acetyl-CoA Carboxylase

2021 ◽  
Author(s):  
John E. Cronan
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Building Block ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Content Type ◽  
Malonyl Coa

SUMMARY Escherichia coli acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of the malonyl-CoA, the building block of fatty acid synthesis, is the paradigm bacterial ACC. Many reports on the structures and stoichiometry of the four subunits comprising the active enzyme as well as on regulation of ACC activity and expression have appeared in the almost 20 years since this subject was last reviewed. This review seeks to update and expand on these reports.

scholarly journals HFA1 Encoding an Organelle-specific Acetyl-CoA Carboxylase Controls Mitochondrial Fatty Acid Synthesis inSaccharomyces cerevisiae

2004 ◽  
Vol 279 (21) ◽  
pp. 21779-21786 ◽  
Author(s):  
Ursula Hoja ◽  
Sandra Marthol ◽  
Jörg Hofmann ◽  
Sabine Stegner ◽  
Rainer Schulz ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Mitochondrial Fatty Acid

scholarly journals Engineering intracellular malonyl-CoA availability in microbial hosts and its impact on polyketide and fatty acid synthesis

2020 ◽  
Vol 104 (14) ◽  
pp. 6057-6065 ◽  
Author(s):  
Lars Milke ◽  
Jan Marienhagen
Keyword(s):  
Fatty Acid ◽  
Metabolic Engineering ◽  
Fatty Acid Synthesis ◽  
Building Block ◽  
Acid Synthesis ◽  
Microbial Synthesis ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Cell Factories ◽  
Malonyl Coa

AbstractMalonyl-CoA is an important central metabolite serving as the basic building block for the microbial synthesis of many pharmaceutically interesting polyketides, but also fatty acid–derived compounds including biofuels. Especially Saccharomyces cerevisiae, Escherichia coli, and Corynebacterium glutamicum have been engineered towards microbial synthesis of such compounds in recent years. However, developed strains and processes often suffer from insufficient productivity. Usually, tightly regulated intracellular malonyl-CoA availability is regarded as the decisive bottleneck limiting overall product formation. Therefore, metabolic engineering towards improved malonyl-CoA availability is essential to design efficient microbial cell factories for the production of polyketides and fatty acid derivatives. This review article summarizes metabolic engineering strategies to improve intracellular malonyl-CoA formation in industrially relevant microorganisms and its impact on productivity and product range, with a focus on polyketides and other malonyl-CoA-dependent products.Key Points• Malonyl-CoA is the central building block of polyketide synthesis.• Increasing acetyl-CoA supply is pivotal to improve malonyl-CoA availability.• Improved acetyl-CoA carboxylase activity increases availability of malonyl-CoA.• Fatty acid synthesis as an ambivalent target to improve malonyl-CoA supply.

scholarly journals Chronic ethanol administration depresses fatty acid synthesis in rat adipose tissue

1988 ◽  
Vol 251 (2) ◽  
pp. 547-551 ◽  
Author(s):  
J S Wilson ◽  
M A Korsten ◽  
L P Donnelly ◽  
P W Colley ◽  
J B Somer ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Chronic Ethanol ◽  
Ethanol Administration ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Chronic Ethanol Administration

Administration of ethanol as part of a nutritionally adequate liquid diet to female Wistar rats was found to depress markedly incorporation of labelled glucose into adipose-tissue acylglycerol fatty acids. Similar results with labelled pyruvate and acetate suggested inhibition of the fatty-acid-synthesis pathway at, or distal to, the acetyl-CoA carboxylase step. Activities of acetyl-CoA carboxylase and fatty acid synthetase were markedly lower in ethanol-fed animals. The activity of another lipogenic enzyme, phosphatidate phosphohydrolase, was not affected by chronic ethanol feeding. These findings suggest that chronic ethanol administration has marked effects on adipose-tissue lipogenesis.

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