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.

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.

scholarly journals The Two Carboxylases of Corynebacterium glutamicum Essential for Fatty Acid and Mycolic Acid Synthesis

2007 ◽  
Vol 189 (14) ◽  
pp. 5257-5264 ◽  
Author(s):  
Roland Gande ◽  
Lynn G. Dover ◽  
Karin Krumbach ◽  
Gurdyal S. Besra ◽  
Hermann Sahm ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Corynebacterium Glutamicum ◽  
Acid Synthesis ◽  
Mycolic Acid ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Α Subunit ◽  
Mycolic Acids

ABSTRACT The suborder Corynebacterianeae comprises bacteria like Mycobacterium tuberculosis and Corynebacterium glutamicum, and these bacteria contain in addition to the linear fatty acids, unique α-branched β-hydroxy fatty acids, called mycolic acids. Whereas acetyl-coenzyme A (CoA) carboxylase activity is required to provide malonyl-CoA for fatty acid synthesis, a new type of carboxylase is apparently additionally present in these bacteria. It activates the α-carbon of a linear fatty acid by carboxylation, thus enabling its decarboxylative condensation with a second fatty acid to afford mycolic acid synthesis. We now show that the acetyl-CoA carboxylase of C. glutamicum consists of the biotinylated α-subunit AccBC, the β-subunit AccD1, and the small peptide AccE of 8.9 kDa, forming an active complex of approximately 812,000 Da. The carboxylase involved in mycolic acid synthesis is made up of the two highly similar β-subunits AccD2 and AccD3 and of AccBC and AccE, the latter two identical to the subunits of the acetyl-CoA carboxylase complex. Since AccD2 and AccD3 orthologues are present in all Corynebacterianeae, these polypeptides are vital for mycolic acid synthesis forming the unique hydrophobic outer layer of these bacteria, and we speculate that the two β-subunits present serve to lend specificity to this unique large multienzyme complex.

scholarly journals Staphylococcus aureus Fatty Acid Auxotrophs Do Not Proliferate in Mice

2013 ◽  
Vol 57 (11) ◽  
pp. 5729-5732 ◽  
Author(s):  
Joshua B. Parsons ◽  
Matthew W. Frank ◽  
Jason W. Rosch ◽  
Charles O. Rock
Keyword(s):  
Fatty Acids ◽  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Normal Growth ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Content Type

ABSTRACTInactivation of acetyl-coenzyme A (acetyl-CoA) carboxylase confers resistance to fatty acid synthesis inhibitors inStaphylococcus aureuson media supplemented with fatty acids. The addition ofanteiso-fatty acids (1 mM) plus lipoic acid supports normal growth of ΔaccDstrains, but supplementation with mammalian fatty acids was less efficient. Mice infected with strain RN6930 developed bacteremia, but bacteria were not detected in mice infected with its ΔaccDderivative.S. aureusbacteria lacking acetyl-CoA carboxylase can be propagatedin vitrobut were unable to proliferate in mice, suggesting that the acquisition of inactivating mutations in this enzyme is not a mechanism for the evasion of fatty acid synthesis inhibitors.

scholarly journals Differential effects of 2-oxo acids on pyruvate utilization and fatty acid synthesis in rat brain

1974 ◽  
Vol 140 (1) ◽  
pp. 25-29 ◽  
Author(s):  
John B. Clark ◽  
John M. Land
Keyword(s):  
Fatty Acid ◽  
Pyruvate Dehydrogenase ◽  
Citrate Synthase ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Synthetase Activity ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Old Rats

1. The effects of 2-oxo-4-methylpentanoate, 2-oxo-3-methylbutanoate and 2-oxo-3-methylpentanoate on the activity of pyruvate dehydrogenase (EC 1.2.4.1), citrate synthase (EC 4.1.3.7), acetyl-CoA carboxylase, (EC 6.4.1.2) and fatty acid synthetase derived from the brains of 14-day-old rats were investigated. 2. The pyruvate dehydrogenase enzyme activity was competitively inhibited by 2-oxo-3-methylbutanoate with respect to pyruvate with a Ki of 2.04mm but was unaffected by 2-oxo-4-methylpentanoate or 2-oxo-3-methylpentanoate. 3. The citrate synthase activity was inhibited competitively (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (Ki~7.2mm) and 2-oxo-3-methylbutanoate (Ki~14.9mm) but not by 2-oxo-3-methylpentanoate. 4. The acetyl-CoA carboxylase activity was not inhibited significantly by any of the 2-oxo acids investigated. 5. The fatty acid synthetase activity was competitively inhibited (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (Ki~930μm) and 2-oxo-3-methylpentanoate (Ki~3.45mm) but not by 2-oxo-3-methylbutanoate. 6. Preliminary experiments indicate that 2-oxo-4-methylpentanoate and 2-oxo-3-phenylpropionate (phenylpyruvate) significantly inhibit the ability of intact brain mitochondria from 14-day-old rats to oxidize pyruvate. 7. The results are discussed with reference to phenylketonuria and maple-syrup-urine disease. A biochemical mechanism is proposed to explain the characteristics of these diseases.

scholarly journals Metabolic adaptations during lactogenesis. Fatty acid and lactose synthesis in cow mammary tissue

1973 ◽  
Vol 136 (3) ◽  
pp. 741-748 ◽  
Author(s):  
R. W. Mellenberger ◽  
D. E. Bauman ◽  
D. R. Nelson
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Post Partum ◽  
Acid Synthesis ◽  
Mammary Tissue ◽  
Acetate Incorporation ◽  
Acetyl Coa Carboxylase ◽  
Tissue Slices ◽  
Acetyl Coa ◽  
Lactose Synthesis

1. Mammary-tissue biopsies were obtained from multiparous cows at 30 and 7 days pre partum and 7 and 40 days post partum. Investigations of the effect of lactogenesis on fatty acid and lactose synthesis involved measurements of biosynthetic capacity (tissue-slice incubations in vitro) and activities of relevant enzymes. 2. Fatty acid synthesis from acetate increased over 20-fold from 30 days pre partum to 40 days post partum. Changes in the lipogenic capacity of mammary-tissue slices more closely paralleled increases in the activities of acetyl-CoA carboxylase (EC 6.4.1.2) and acetyl-CoA synthetase (EC 6.2.1.1) than of other enzymes involved in acetate incorporation into fatty acids or in NADPH generation. 3. Lactose biosynthesis by mammary-tissue slices, lactose synthetase activity (EC 2.4.1.22) and α-lactalbumin concentration were all negligible at 30 days pre partum but increased 2.5–4-fold between 7 days pre partum and 40 days post partum. Phosphoglucomutase (EC 2.7.5.1), UDP-glucose pyrophosphorylase (EC 2.7.7.9) and UDP-glucose 4-epimerase (EC 5.1.3.2) had substantial activities at 30 days pre partum and increased less dramatically during lactogenesis. 4. Results are consistent with acetyl-CoA carboxylase and perhaps acetyl-CoA synthetase representing the regulatory enzyme(s) in fatty acid synthesis, with lactose synthetase (α-lactalbumin) serving a similar function in lactose biosynthesis.

scholarly journals The use of acetyl-CoA carboxylase activity and changes in wall composition as measures of embryogenesis in tissue cultures of oil palm (Elaeis guineensis)

1982 ◽  
Vol 208 (2) ◽  
pp. 323-332 ◽  
Author(s):  
E Turnham ◽  
D H Northcote
Keyword(s):  
Oil Palm ◽  
Elaeis Guineensis ◽  
Acid Synthesis ◽  
Tissue Cultures ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

With some lines of oil-palm tissue cultures embryogenesis occurs spontaneously within the callus grown on a medium containing 2.5 mg of 3-naphthylacetic acid/litre. One of the initial biochemical events that occurs just before the embryoid can be seen is the accumulation of fat droplets within the cells. This accumulation of lipid is correlated with an increase in acetyl-CoA carboxylase activity. The carboxylase is thus probably a rate-limiting step in fatty acid synthesis in these cells and can be used as a quantitative marker of somatic embryogenesis within the tissue. During the development of the embryoid tissue there is an increase in cell division and the differentiation of vascular cells with secondary thickened walls. These stages of the differentiation may be monitored by measuring the ratio of pectin synthesis (polygalacturonic acid formation) to hemicellulose synthesis (xylan formation).

scholarly journals Rat mammary-gland acetyl-coenzyme A carboxylase. Interaction with milk fatty acids

1970 ◽  
Vol 118 (4) ◽  
pp. 645-657 ◽  
Author(s):  
A. L. Miller ◽  
Mary E. Geroch ◽  
H. Richard Levy
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Complex Mixture ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
High Concentration ◽  
Acetyl Coa ◽  
Milk Fatty Acids ◽  
Low Concentrations ◽  
Rat Mammary Gland

1. Highly purified rat mammary-gland acetyl-CoA carboxylase was inhibited by milk obtained from rats 12h after their young were weaned. 2. All the inhibitory activity was found in the particulate fraction (R105) obtained on centrifuging the milk. It could be extracted from milk fraction R105 with acetone and identified as a complex mixture of non-esterified fatty acids, present in high concentration (nearly 10mm) in the milk. 3. Inhibition of acetyl-CoA carboxylase was observed at low concentrations (0.2–20μm) of several of these fatty acids when fresh fully active enzyme was used. Enzyme that had been partly inactivated by aging, or by storing in the absence of citrate, was stimulated by low concentrations but inhibited by high concentrations of fatty acids. 4. Various experiments suggested that fatty acids produce irreversible inactivation of acetyl-CoA carboxylase. 5. The effects of palmitoyl-CoA on mammary-gland acetyl-CoA carboxylase were found to resemble those of fatty acids, except that palmitoyl-CoA was effective at lower concentration. 6. The effect of milk fraction R105 was tested on six other enzymes previously shown to decline to various extents after weaning. Although several of these enzymes were affected by unfractionated milk fraction R105, none was significantly inhibited by the acetone extract or by low concentrations of lauric acid. 7. The findings are consistent, both qualitatively and quantitatively, with a regulatory mechanism whereby milk fatty acids shut off fatty acid synthesis in the mammary gland after weaning by inhibiting acetyl-CoA carboxylase.

scholarly journals Polyunsaturated fatty acids decrease the expression of sterol regulatory element-binding protein-1 in CaCo-2 cells: effect on fatty acid synthesis and triacylglycerol transport

2002 ◽  
Vol 368 (3) ◽  
pp. 855-864 ◽  
Author(s):  
F. Jeffrey FIELD ◽  
Ella BORN ◽  
Shubha MURTHY ◽  
Satya N. MATHUR
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Protein Expression ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Mrna Levels ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Endogenous Fatty Acid ◽  
Gene And Protein Expression

Regulation of sterol regulatory element-binding proteins (SREBPs) by fatty acid flux was investigated in CaCo-2 cells. Cells were incubated with 1mM taurocholate with or without 250μM 18:0, 18:1, 18:2, 20:4, 20:5 or 22:6 fatty acids. Fatty acid synthase (FAS) and acetyl-CoA carboxylase mRNA levels and gene and protein expression of SREBPs were estimated. 18:2, 20:4, 20:5 and 22:6 fatty acids decreased the amount of mature SREBP-1 and mRNA levels of SREBP-1c, SREBP-1a, FAS and acetyl-CoA carboxylase. SREBP-2 gene or mature protein expression was not altered. Liver X receptor (LXR) activation by T0901317 increased gene expression of SREBP-1c, SREBP-1a, FAS and acetyl-CoA carboxylase without altering SREBP-2. 20:5, but not 18:1, prevented the full expression of SREBP-1c mRNA by T0901317. T0901317 increased SREBP-1 mass without altering the mass of mature SREBP-2. Although only 18:2, 20:4, 20:5 and 22:6 suppressed SREBP-1, acetyl-CoA carboxylase and FAS expression, all fatty acids decreased the rate of fatty acid synthesis. T0901317 increased endogenous fatty acid synthesis yet did not increase secretion of triacylglycerol-rich lipoproteins. In CaCo-2 cells, polyunsaturated fatty acids decrease gene and protein expression of SREBP-1 and FAS mRNA, probably through interference with LXR activity. Since all fatty acids decreased fatty acid synthesis, mechanisms other than changes in SREBP-1c expression must be entertained. Increased endogenous fatty acid synthesis does not promote triacylglycerol-rich lipoprotein secretion.

scholarly journals Evidence for a protein regulator from rat liver which activates acetyl-CoA carboxylase

1993 ◽  
Vol 292 (1) ◽  
pp. 75-84 ◽  
Author(s):  
K A Quayle ◽  
R M Denton ◽  
R W Brownsey
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
High Speed ◽  
Deae Cellulose ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity

1. A regulator of acetyl-CoA carboxylase has been identified in high-speed supernatant fractions from rat liver. The regulator was found to activate highly purified acetyl-CoA carboxylase 2-3-fold at physiological citrate concentrations (0.1-0.5 mM). The effects of the regulator on acetyl-CoA carboxylase activity were dose-dependent, and half-maximal activation occurred in 7-8 min at 30 degrees C. 2. The acetyl-CoA carboxylase regulator was non-dialysable and was inactivated by heating or by exposure to carboxypeptidase. The regulator was enriched from rat liver cytosol by first removing the endogenous acetyl-CoA carboxylase and then using a combination of purification steps, including (NH4)2SO4 precipitation, ion-exchange chromatography and size-exclusion chromatography. The regulator activity appeared to be a protein with a molecular mass of approx. 75 kDa, which could be eluted from mono-Q with approx. 0.35 M KCl as a single peak of activity. 3. Studies of the effects of the regulator on phosphorylation or subunit size of acetyl-CoA carboxylase indicated that the changes in enzyme activity are most unlikely to be explained by dephosphorylation or by proteolytic cleavage. 4. The regulator co-migrates with acetyl-CoA carboxylase through several purification steps, including ion-exchange chromatography and precipitation with (NH4)2SO4; however, the proteins may be separated by Sepharose-avidin chromatography, and the association between the proteins is also disrupted by addition of avidin in solution. Furthermore, the binding of the regulator itself to DEAE-cellulose is altered by the presence of acetyl-CoA carboxylase. Taken together, these observations suggest that the effects of the regulator on acetyl-CoA carboxylase may be explained by direct protein-protein interaction in vitro.

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