scholarly journals Changes in the activity of acetyl-CoA carboxylase during rape-seed formation

1983 ◽  
Vol 212 (1) ◽  
pp. 223-229 ◽  
Author(s):  
E Turnham ◽  
D H Northcote
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Acetyl Coa Carboxylase ◽  
Rape Seed ◽  
Acetyl Coa ◽  
Marked Rise ◽  
Carboxylase Activity ◽  
Seed Formation ◽  
Lipid Formation ◽  
Seed Extracts

During the formation of rape-seeds, lipid accumulated in the cotyledons from 16 days after pollination, rising to a plateau after 28 days. The accumulation of lipid was preceded by a marked rise in acetyl-CoA carboxylase activity, which declined rapidly, correlating with the decline in rate of lipid formation. Incubation of rape-seed extracts with avidin-agarose resulted in a decrease in acetyl-CoA carboxylase activity in the extract. Polyacrylamide-gel electrophoresis of polypeptides bound to avidin-agarose showed the presence of a polypeptide of Mr 225 000. The intensity of this band increased during the period of increase of acetyl-CoA carboxylase activity in the seeds.

scholarly journals Changes in mammary-gland acetyl-coenzyme A carboxylase associated with lactogenic differentiation

1977 ◽  
Vol 162 (3) ◽  
pp. 635-642 ◽  
Author(s):  
Julia C. Mackall ◽  
M. Daniel Lane
Keyword(s):  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Mammary Tissue ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Liver Cytosol ◽  
Lactogenic Differentiation

The process leading to the rise of acetyl-CoA carboxylase activity in rat mammary tissue after the onset of lactation was investigated. The kinetics of change in enzyme activity and enzyme immunotitratable with antibody against avian liver acetyl-CoA carboxylase were determined during the course of lactogenic differentiation. The antibody inactivates and specifically precipitates acetyl-CoA carboxylase from rat mammary tissue as well as that from chicken liver cytosol. Characterization of the immunoprecipitate of the mammary tissue carboxylase by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis reveals a single biotin-containing polypeptide of about 230000mol.wt. This molecular weight is approximately twice that reported for the avian liver enzyme. However, chicken liver cytosol prepared in the presence of trypsin inhibitor and subjected to immunoprecipitation gives rise to a biotin-containing subunit of 230000mol.wt. as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis; omission of proteinase inhibitor leads to a subunit(s) approximately one-half this size. Throughout gestation both carboxylase activity and amounts of immunotitratable enzyme remained low; however, after parturition both parameters rose concomitantly to values 30–40 times the initial values. Therefore the elevated concentration of acetyl-CoA carboxylase appears to result from an increased rate of synthesis of enzyme relative to degradation rather than to activation of a pre-existing form of the enzyme.

scholarly journals Critical phosphorylation sites for acetyl-CoA carboxylase activity.

1994 ◽  
Vol 269 (35) ◽  
pp. 22162-22168 ◽  
Author(s):  
J. Ha ◽  
S. Daniel ◽  
S.S. Broyles ◽  
K.H. Kim
Keyword(s):  
Phosphorylation Sites ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity

Relative Activities of Acetyl-CoA Carboxylase and Fatty Acid Synthetase in Chick Liver: Effects of Dietary Fat

1973 ◽  
Vol 51 (7) ◽  
pp. 1029-1033 ◽  
Author(s):  
Gregory I. Liou ◽  
W. E. Donaldson
Keyword(s):  
Fatty Acid ◽  
Corn Oil ◽  
Fatty Acid Synthetase ◽  
Basal Diet ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Cytosol Fraction ◽  
Activity Concentrations

The specific activities of acetyl-CoA carboxylase and fatty acid synthetase were measured in the cytosol fraction of livers from chicks fed various levels of corn oil, cottonseed oil, corn-oil free fatty acids, or crude (79%) oleic acid. Activities of both enzymes were depressed by the addition of fat to a fat-free basal diet. The ratios of synthetase to carboxylase activity were greater than unity when up to 4% fat was fed, but less than unity when 8% or higher levels of fat were fed. The depressions of the activities of these enzymes appeared to be unrelated to the dietary level of linoleate. In in vitro experiments, 2 μM concentrations of palmityl-CoA or oleoyl-CoA depressed acetyl-CoA carboxylase activity. Concentrations of 20 μM of these acyl-CoA esters did not affect the activity of fatty acid synthetase.

scholarly journals Growth-hormone-prolactin interactions in the regulation of mammary and adipose-tissue acetyl-CoA carboxylase activity and gene expression in lactating rats

1992 ◽  
Vol 285 (2) ◽  
pp. 469-475 ◽  
Author(s):  
M C Barber ◽  
M T Travers ◽  
E Finley ◽  
D J Flint ◽  
R G Vernon
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Serum Prolactin ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Total Enzyme Activity ◽  
Mrna Concentration ◽  
Total Enzyme ◽  
Activation Status

The factors and mechanisms responsible for the reciprocal changes in lipogenesis in rat mammary gland and adipose tissue during the lactation cycle have been investigated. Lactation decreased the activation status and mRNA concentration of acetyl-CoA carboxylase in adipose tissue. Litter removal decreased the mRNA concentration of acetyl-CoA carboxylase in the mammary gland and increased the enzyme's mRNA concentration and activation status in adipose tissue. Lowering serum prolactin concentration in lactating rats decreased the amount of mammary acetyl-CoA carboxylase mRNA and increased that of adipose tissue, and increased the activation status of the enzyme in adipose tissue. Decreasing serum growth hormone (GH) alone had little effect on acetyl-CoA carboxylase in lactating rats, although it did lower pup growth rate and serum concentration of insulin-like growth factor-I. Lowering serum GH concentration exacerbated the effects of decreasing serum prolactin on mammary-gland (but not adipose-tissue) acetyl-CoA carboxylase mRNA and further increased the rise in activation status of the adipose-tissue enzyme induced by decreasing serum prolactin. Changes in acetyl-CoA carboxylase mRNA in both mammary and adipose tissue were paralleled by changes in total enzyme activity except after litter removal, when there was a disproportionately large decrease in total enzyme activity of the mammary gland. Thus prolactin has a major and GH a minor role in the regulation of acetyl-CoA carboxylase activity during lactation. Changes in mammary activity in response to prolactin and GH are primarily due to alterations in gene transcription, whereas adaptation in adipose tissue involves both changes in gene transcription and activation status.

scholarly journals Association between Hydrogen Peroxide-Dependent Byproducts of Ascorbic Acid and Increased Hepatic Acetyl-CoA Carboxylase Activity

2005 ◽  
Vol 51 (8) ◽  
pp. 1462-1471 ◽  
Author(s):  
Laurent Knafo ◽  
Philippe Chessex ◽  
Thérèse Rouleau ◽  
Jean-Claude Lavoie
Keyword(s):  
Ascorbic Acid ◽  
Lipid Metabolism ◽  
Guinea Pig ◽  
Dehydroascorbic Acid ◽  
Biologically Active ◽  
Urinary Concentration ◽  
Acetyl Coa Carboxylase ◽  
High Concentration ◽  
Acetyl Coa ◽  
Carboxylase Activity

Abstract Background: Parenteral multivitamin preparation (MVP) induces fatty liver in neonatal guinea pig pups; this is prevented by photoprotection. Photo-excited riboflavin present in MVP generates H2O2 and molecules with masses of 136 and 208. We hypothesized that H2O2 initiates the peroxidation of ascorbic acid (AA), producing biologically active byproducts affecting hepatic lipid metabolism. Methods: Mass spectrometry (MS) documented the participation of H2O2 and photo-excited riboflavin (Ribo) in the formation of AA byproducts. Sixteen 3-day-old guinea pig pups received an intravenous solution (50 g/L dextrose + 4.5 g/L NaCl + 1 kIU/L heparin) at 240 mL · kg−1 · day−1, enriched with control or test mixtures, for 4 days. The control mixture was photo-protected AA + Ribo (without byproducts or H2O2), and the test mixture was AA + Ribo treated to generate AA byproducts without H2O2. Hepatic acetyl-CoA carboxylase (ACC) activity was determined after 4 days. Fourth-day urine samples were analyzed by MS. Data were treated by ANOVA (α = 0.05). Results: H2O2 did not influence the classic degradation of AA, as the generation of 2,3-diketogulonic acid was not affected. In contrast, the formation of molecules with masses of 136 and 208 was H2O2 and time dependent. ACC activity was higher (P <0.01) in animals receiving high concentration of these molecules; its hepatic activation correlated (P <0.01) with the urinary concentration of molecule-208. Conclusions: H2O2 at concentrations found in the clinical setting of total parenteral nutrition induce the transformation of dehydroascorbic acid into compounds that have the potential to affect lipid metabolism. These molecules have peroxide and aldehyde functions.

scholarly journals Both insulin and epidermal growth factor stimulate lipogenesis and acetyl-CoA carboxylase activity in isolated adipocytes. Importance of homogenization procedure in avoiding artefacts in acetyl-CoA carboxylase assay

1986 ◽  
Vol 234 (2) ◽  
pp. 279-284 ◽  
Author(s):  
T A Haystead ◽  
D G Hardie
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Maximal Effect ◽  
Acetyl Coa Carboxylase ◽  
Homogenization Procedure ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Epidermal Growth ◽  
Isolated Adipocytes ◽  
Significant Interference

Epidermal growth factor (EGF) stimulates lipogenesis by 3-4-fold in isolated adipocytes, with a half-maximal effect at 10 nM-EGF. In the same batches of cells insulin stimulated lipogenesis by 15-fold. Freezing and prolonged homogenization of adipocytes results in release of large quantities of pyruvate carboxylase from broken mitochondria, and sufficient pyruvate can be carried through into assays for this enzyme to cause significant interference with assays of acetyl-CoA carboxylase in crude adipocyte extracts. This may account for the high amount of citrate-independent acetyl-CoA carboxylase activity reported to be present in adipocyte extracts in some previous publications. This problem may be eliminated by homogenizing very briefly without freezing. By using the modified homogenization procedure, EGF treatment of adipocytes was shown to produce an effect on acetyl-CoA carboxylase activity almost identical with that of insulin. Both messengers increase Vmax. without significant effect on the Ka for the allosteric activator, citrate.

scholarly journals Insulin activation of lipogenesis in isolated mammary acini from lactating rats fed on a high-fat diet. Evidence that acetyl-CoA carboxylase is a site of action

1987 ◽  
Vol 242 (3) ◽  
pp. 905-911 ◽  
Author(s):  
M R Munday ◽  
D H Williamson
Keyword(s):  
Glucose Uptake ◽  
High Fat Diet ◽  
Acetyl Coa Carboxylase ◽  
High Fat ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Glucose Incorporation ◽  
Site Of Action ◽  
A Site

Feeding lactating rats on high-fat cheese crackers in addition to laboratory chow increased the dietary intake of fat from 2 to 20% of the total weight of food eaten and decreased mammary-gland lipogenesis in vivo by approx. 50%. This lipogenic inhibition was also observed in isolated mammary acini, where it was accompanied by decreased glucose uptake. These inhibitions were completely reversed by incubation with insulin. Insulin had no effect on the rate of glucose transport into acini, nor on pyruvate dehydrogenase activity as estimated by the accumulation of pyruvate and lactate, suggesting that these are not the sites of lipogenic inhibition. Insulin stimulated the incorporation of [1-14C]acetate into lipid in acini from high-fat-fed rats. In the presence of alpha-cyanohydroxycinnamate, a potent inhibitor of mitochondrial pyruvate transport, and with glucose as the sole substrate, neither [1-14C]glucose incorporation into lipid nor glucose uptake were stimulated by insulin. Insulin did stimulate the incorporation of [1-14C]acetate into lipid in the presence of alpha-cyanohydroxycinnamate, and this was accompanied by an increase in glucose uptake by the acini. This indicated that increased glucose uptake was secondary to the stimulation of lipogenesis by insulin, which therefore must occur via activation of a step in the pathway distal to mitochondrial pyruvate transport. Insulin stimulated acetyl-CoA carboxylase activity measured in crude extracts of acini from high-fat-fed rats, restoring it to values close to those of chow-fed controls. The effects of insulin on acetyl-CoA carboxylase activity and lipogenesis were not antagonized by adrenaline or dibutyryl cyclic AMP.

scholarly journals The sensitivity of acetyl-coenzyme A carboxylase to citrate stimulation in a homogenate of rat liver containing subcellular particles

1970 ◽  
Vol 117 (2) ◽  
pp. 385-395 ◽  
Author(s):  
Jill Iliffe ◽  
N. B. Myant
Keyword(s):  
Fatty Acids ◽  
Rat Liver ◽  
Specific Radioactivity ◽  
Acid Synthesis ◽  
Acetate Incorporation ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Highly Sensitive ◽  
Activated State

1. Although citrate is known to activate purified preparations of acetyl-CoA carboxylase, it had no stimulatory effect on the incorporation of [14C]acetate into long-chain fatty acids in a whole homogenate of rat liver (S0.7) under conditions in which the activity of acetyl-CoA carboxylase was rate-limiting for fatty acid synthesis. 2. The rate of incorporation of acetyl carbon into fatty acids was estimated in S0.7 preparations incubated with [14C]acetate, by measuring the specific radioactivity of the acetyl carbon of acetyl-CoA and the incorporation of 14C into fatty acids. These estimates were compared with estimates of acetyl-CoA carboxylase activity in the S0.7 preparation obtained by direct assay in conditions in which the enzyme was in the fully activated state. 3. In the absence of citrate, incorporation of acetyl carbon into fatty acids was about 75% of the value expected if the acetyl-CoA carboxylase in the S0.7 preparation were in the fully activated state. 4. Incorporation of acetyl carbon into fatty acids in the S0.7 preparation was stimulated by citrate, but the effect was many times less than the stimulation of [14C]acetate incorporation by citrate in particle-free preparations. 5. When the mitochondria and microsomes were removed from the S0.7 preparation, [14C]acetate incorporation into fatty acids fell to a negligible value and the preparation became highly sensitive to stimulation by citrate. 6. It is suggested that in the presence of mitochondria and microsomes, and in the intact liver cell, the degree of activation of acetyl-CoA carboxylase is such that citrate activation may not be of physiological significance.

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