Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acetyl-CoA carboxylase (E.C. 6.4.1.2) was isolated from rat liver. The purified enzyme contains phospholipids with a rather large amount of phosphatidylinositol (26%). Incubation of the purified acetyl-CoA carboxylase with phospholipase A2 (E.C. 3.1.1.4) or with phospholipase D (E.C. 3.1.1.4) diminishes the phospholipid content by 70%, this treatment leading to a complete inactivation of the enzyme. After removal of the phospholipases, the lipid-depleted enzyme can be reactivated to a certain degree by incubation with a phospholipid extract from rat liver, with phosphatidylinositol alone, or with serum albumin.
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PMID:Effects of phospholipids in the action of acetyl-CoA carboxylase from rat liver. 1 56

If acetyl-CoA carboxylase in epididymal fat tissue is subject to control by convalent modification as in the case of the liver enzyme, catalytically different forms of carboxylase should exist, independent of polymerization. By treating epididymal fat tissue in culture with epinephrine, we have demonstrated catalytically less active forms of acetyl-CoA carboxylase. The catalytically less active forms of the enzyme reacted to antibody with the same efficiency as the active form of carboxylase. However, the less active enzyme formed by epinephrine treatment of tissues has a sedimentation constant of 30 to 35 S, whereas that of the enzyme from control tissue is 45 S. Incubation of the less active forms of the carboxylase with 10 mM citrate and up to 10 mg/ml of bovine serum albumin activated the enzyme without any change in the sedimentation constant. Therefore, the less active forms of the carboxylase formed as a result of epinephrine treatment are not due to the depolymerization of polymeric forms (45 S) to the protomeric forms (17 to 20 S), but to the formation of intermediate species of carboxylase which cannot form polymeric enzyme (45 S) in the presence of high concentrations of citrate.
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PMID:Effect of epinephrine on acetyl-CoA carboxylase in rat epididymal fat tissue. 3 Jul 75

The utilization of lactate, glucose, 3-hydroxybutyrate, and glutamine has been studied in isolated brain cells from early newborn rats. Isolated brain cells actively utilized these substrates, showing saturation at concentrations near physiological levels during the perinatal period. The rate of lactate utilization was 2.5-fold greater than that observed for glucose, 3-hydroxybutyrate, or glutamine, suggesting that lactate is the main metabolic substrate for the brain immediately after birth. The apparent Km for glucose utilization suggested that this process is limited by the activity of hexokinase. However, lactate, 3-hydroxybutyrate, and glutamine utilization seems to be limited by their transport through the plasma membrane. The presence of fatty acid-free bovine serum albumin (BSA) in the incubation medium significantly increased the rate of lipogenesis from lactate or 3-hydroxybutyrate, although this was balanced by the decrease in their rates of oxidation in the same circumstances. BSA did not affect the rate of glucose utilization. The effect of BSA was due not to the removal of free fatty acid, but possibly to the binding of long-chain acyl-CoA, resulting in the disinhibition of acetyl-CoA carboxylase and citrate carrier.
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PMID:Lactate utilization by isolated cells from early neonatal rat brain. 191 82

Acetyl-CoA carboxylase is activated by physiological concentrations of CoA. Activation of partially purified enzyme by CoA is accompanied by a decrease in the Km for acetyl-CoA from 0.2 mM to about 4 microM, which is the physiological concentration of acetyl-CoA in the cytosol. CoA activation of the purified enzyme is accompanied by an increase in the Vmax, without changing the Km for acetyl-CoA. The Km for acetyl-CoA of the purified enzyme is about 10 to 40 microM. The purification procedure results in a decrease in the Km for acetyl-CoA; under these conditions, CoA activation does not cause further lowering of the Km. CoA activation is accompanied by polymerization of the enzyme. However, CoA activation is not causally related to polymerization. There is one CoA binding site/subunit of acetyl-CoA carboxylase. CoA binding at that site is not affected by the presence of citrate, but palmityl-CoA inhibits CoA binding. CoA alone cannot reverse palmityl-CoA inhibition of the carboxylase. Bovine serum albumin and CoA together can activate the palmityl-CoA-inhibited enzyme. This indicates that the involvement of bovine serum albumin-like protein, CoA, and palmityl-CoA may play a physiologically significant role in the control of acetyl-CoA carboxylase.
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PMID:Coenzyme A activation of acetyl-CoA carboxylase. 610 27

Biotin-binding antibodies were raised in rabbits by injecting biotin-bovine serum albumin conjugate. Neither the protomer nor the polymer of rat mammary-gland acetyl-CoA carboxylase formed precipitin bands with the anti-biotin. By virtue of its ability to bind biotin (apparent binding constant for free biotin about 1mum), the anti-biotin inhibited the carboxylase activity under certain conditions. This property of the antibody was employed to detect the ligand-induced changes affecting the biotinyl group in different conformational states of mammalian carboxylase. Depending on the ligand present, the biotinyl group in the protomeric form was either accessible or inaccessible to the antibody. The biotinyl group of the protomer generated by a relatively high concentration of NaCl (0.5m) reacted with the antibody, and the antibody-carboxylase complex could not be converted into active enzyme by citrate. Further experiments showed that citrate failed to induce polymerization in this protomer-antibody complex and that anti-biotin could be displaced rapidly from this complex with excess of biotin. The resulting protomer was converted into the polymeric state on citrate addition, with parallel regain of enzyme activity. In the presence of ADP+Mg(2+), ATP+Mg(2+) or ATP+Mg(2+)+HCO(3) (-), however, the enzyme remained as a protomer, but its configuration was such that the biotinyl group was essentially inaccessible to the antibody. Likewise, the biotinyl group of the different polymeric forms of the carboxylase (s approximately 30-45S) engendered by phosphate, malonyl-CoA, acetyl-CoA or citrate remained essentially inaccessible, since their activity was minimally affected by the anti-biotin. In the presence of 0.15m-NaCl, the phosphate-induced polymer reverted to a approximately 19S form with concomitant appearance of anti-biotin-sensitivity, whereas the other polymeric forms remained unaffected under similar experimental conditions.
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PMID:Detection of ligand-induced perturbations affecting the biotinyl group of mammalian acetyl-coenzyme A carboxylase by using biotin-binding antibodies. 611 76

Preparations of acetyl-CoA carboxylase [acetyl-CoA-carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] have been obtained from the plastids of avocado (Persea americana) fruit mesocarp and from spinach (Spinacia oleracea) chloroplasts. Both preparations required bovine serum albumin, HCO3-, citrate and glycerol for stabilization. The molecular weight of the avocado enzyme was about 6.5 X 10(5) on the basis of 1 mol of biotin/mol of enzyme, the behaviour of both enzymes on gel filtration being in accord with such a value. Removal of the stabilizing bovine serum albumin resulted in the loss of a biotin-containing fragment from the avocado enzyme. Citrate stabilized the enzyme at 10 mM and activated it optimally at 3.0 mM, effecting an approx. 2-fold increase in Vmax. It is suggested that in vivo the enzyme may be located within the chloroplast lamellae.
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PMID:Acetyl-coenzyme A carboxylase from avocado (Persea americana) plastids and spinach (Spinacia oleracea) chloroplasts. 614 8

The regulation of acetyl-CoA carboxylase and malonyl-CoA levels in skeletal muscle may involve a calcium-dependent mechanism. To examine the effects of increased free sarcoplasmic calcium concentrations on malonyl-CoA in skeletal muscle, isolated hindlimbs of rats were perfused for 30 min with a medium containing bovine red blood cells, bovine serum albumin, 200 microU/ml insulin, and 10 mM glucose in Krebs-Henseleit buffer and caffeine at 0, 0.12, 0.5, or 3 mM. Malonyl-CoA decreased from control (no caffeine) values of 1.34 +/- 0.9 to 0.95 +/- 0.12 pmol/mg in gastrocnemius-plantaris muscles perfused with 0.12 and 0.5 mM caffeine and to 0.63 +/- 0.07 pmol/mg in the muscles perfused with 3 mM caffeine. Adenosine 3',5'-cyclic monophosphate (cAMP) increased from 0.24 +/- 0.02 to 0.32 +/- 0.04 nmol/g, and AMP decreased from 83 +/- 8 to 53 +/- 3 nmol/g in response to 3 mM caffeine. Citrate and ATP were unaffected by caffeine. A decline in malonyl-CoA with 0.12 and 0.5 mM caffeine without an increase in cAMP supports the hypothesis that a calcium-dependent mechanisms of acetyl-CoA carboxylase and malonyl-CoA regulation exists, but a cAMP-dependent mechanism may also be involved with 3 mM caffeine.
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PMID:Caffeine decreases malonyl-CoA in isolated perfused skeletal muscle of rats. 761 61

The possible role played by albumin in regulating brain metabolism during development has been studied. The effects of fatty acid-free BSA on lactate, glucose, 3-hydroxybutyrate, and glutamine oxidation and lipogenesis by rat neurons and astrocytes from primary culture were studied. The rate of lactate oxidation and lipogenesis by neurons and astrocytes in the presence of BSA greatly exceeded that observed for glucose, 3-hydroxybutyrate, or glutamine, suggesting that lactate may be a key substrate for brain development. BSA strongly stimulated the rate of lactate, 3-hydroxybutyrate, and glutamine incorporation into lipids in both neurons (677%, 726%, and 250%, respectively) and astrocytes (415%, 393%, and 215%, respectively), possibly by binding long-chain acyl-CoA excesses, potent inhibitors of acetyl-CoA carboxylase. However, BSA decreased the rate of lipogenesis from glucose in both neurons (34%) and astrocytes (55%), probably by inhibiting glycerol-borne phospholipid synthesis. BSA significantly increased the rates of lactate (61%) and glucose (32%) oxidation by astrocytes but not those of 3-hydroxybutyrate and glutamine, suggesting that BSA may stimulate pyruvate oxidation. However, in neurons BSA did not affect the rate of oxidation of any of the substrates tested, which suggests that pyruvate oxidation is regulated differently in neurons and astrocytes. The results suggest that lactate is the most important substrate for both neurons and astrocytes, stressing the role played by lactate in brain development. Our results also suggest that serum albumin may control brain development by fostering metabolism for growth and differentiation purposes.
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PMID:Regulation of lactate metabolism by albumin in rat neurons and astrocytes from primary culture. 810 80

5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) has previously been reported to be taken up into cells and phosphorylated to form ZMP, an analog of 5'-AMP. This study was designed to determine whether AICAR can activate AMP-activated protein kinase (AMPK) in skeletal muscle with consequent phosphorylation of acetyl-CoA carboxylase (ACC), decrease in malonyl-CoA, and increase in fatty acid oxidation. Rat hindlimbs were perfused with Krebs-Henseleit bicarbonate containing 4% bovine serum albumin, washed bovine red blood cells, 200 microU/ml insulin, and 10 mM glucose with or without AICAR (0.5-2.0 mM). Perfusion with medium containing AICAR was found to activate AMPK in skeletal muscle, inactivate ACC, and decrease malonyl-CoA. Hindlimbs perfused with 2 mM AICAR for 45 min exhibited a 2.8-fold increase in fatty acid oxidation and a significant increase in glucose uptake. No difference was observed in oxygen uptake in AICAR vs. control hindlimb. These results provide evidence that decreases in muscle content of malonyl-CoA can increase the rate of fatty acid oxidation.
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PMID:AICA riboside increases AMP-activated protein kinase, fatty acid oxidation, and glucose uptake in rat muscle. 943 25

5-Aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR) is taken up by perfused skeletal muscle and phosphorylated to form 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuraosyl-5'-monopho sph ate (analog of 5'-AMP) with consequent activation of AMP-activated protein kinase, phosphorylation of acetyl-CoA carboxylase, decrease in malonyl-CoA, and increase in fatty acid oxidation. This study was designed to determine the effect of increasing levels of palmitate on the rate of fatty acid oxidation. Malonyl-CoA concentration was manipulated with AICAR at different palmitate concentrations. Rat hindlimbs were perfused with Krebs-Henseleit bicarbonate containing 4% bovine serum albumin, washed bovine red cells, 200 microU/ml insulin, 10 mM glucose, and different concentrations of palmitate (0. 1-1.0 mM) without or with AICAR (2.0 mM). Perfusion with medium containing AICAR was found to activate AMP-activated protein kinase in skeletal muscle, inactivate acetyl-CoA carboxylase, and decrease malonyl-CoA at all concentrations of palmitate. The rate of palmitate oxidation increased as a function of palmitate concentration in both the presence and absence of AICAR but was always higher in the presence of AICAR. These results provide additional evidence that malonyl-CoA is an important regulator of the rate of fatty acid oxidation at palmitate concentrations in the physiological range.
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PMID:Influence of malonyl-CoA and palmitate concentration on rate of palmitate oxidation in rat muscle. 980 98


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