Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.13 (acetyl-CoA synthetase)
 451 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Day-old male, broiler type chicks were used to study the effect of 100 ppm dietary vanadium on fatty acid and cholesterol synthesis and turnover in vivo. After feeding the experimental diets for 4 weeks body weight and liver weight of chicks fed 100 ppm vanadium were significantly less than those of the control chicks and liver total lipid and cholesterol tended to be slightly higher than the levels of the control chicks. [1-14C] Acetate was administered intravenously and the specific activities of plasma and liver total lipid, cholesterol and fatty acid were determined at 0.25, 0.50, 1.0, 4.0, 8.0 and 15.0 hours after the injection. Plasma total lipid and cholesterol were significantly higher than the levels in the control chicks. The rate of incorporation of [1-14C]acetate into plasma and liver total lipid, cholesterol and fatty acid was higher in chicks fed vanadium than the control group at any of the time being tested after the injection. There was a significant increase in the hepatic citrate cleavage enzyme activity among chicks fed 100 ppm vanadium, whereas, there was no significant change in acetate thiokinase activity. Turnover rate of plasma total lipid and fatty acid in vanadium fed chicks was lower than the control. The turnover rate of plasma cholesterol determined by administering [4-14C]cholesterol and periodically measuring the specific activity of plasma cholesterol was higher in chicks fed vanadium than in those fed the basal diet.
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PMID:The effect of dietary vanadium on fatty acid and cholesterol synthesis and turnover in the chick. 0 54

Under anaerobic conditions, cells of Entamoeba histolytica grown with bacteria produce H2 and acetate while cells grown axenically produce neither. Aerobically, acetate is produced and O2 is consumed by amebae from either type of cells. Centrifuged extracts, 2.4 x 106 x g x min, from both types of cells contain pyruvate synthase (EC 1.2.7.1) and an acetate thiokinase which, together, form a system capable of converting pyruvate to acetate. Pyruvate synthase catalyzes the reaction: pyruvate + CoA leads to CO2 + acetyl-CoA + 2E. Electron acceptors which function with this enzyme are FAD, FMN, riboflavin, ferredoxin, and methyl viologen, but not NAD or NADP. The amebal acetate thiokinase catalyzes the reaction acetyl-CoA + ADP + Pi leads to acetate + ATP + CoA. For this apparently new enzyme we suggest the trivial name acetyl-CoA-synthetase (ADP-forming). Extracts from axenic amebae do not contain hydrogenase, but extracts from cells grown with bacteria do. It is postulated that in bacteria-grown amebae electrons generated at the pyruvate synthase step are utilized anaerobically to produce H2 via the hydrogenase and that the acetyl-CoA is converted to acetate in an energy-conserving step catalyzed by amebal acetyl-CoA synthetase. Aerobically, cells grown under either regimen may utilize the energy-conserving pyruvate-to-acetate pathway since O2 then serves as the ultimate electron acceptor.
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PMID:An energy-conserving pyruvate-to-acetate pathway in Entamoeba histolytica. Pyruvate synthase and a new acetate thiokinase. 1 76

In light/dark synchronized cultures of Euglena gracilis Klebs Z the enzymes malate synthase, isocitrate lyase and acetate thiokinase were induced upon addition of acetate at all stages of the cell cycle. Cycloheximide and p-fluorophenylalanine inhibited the development of enzyme activity, showing that induction was dependent on protein synthesis. The maximum rate of induction for all three enzymes was constant for much of the cell cycle but doubles in a single step during the period of DNA replication. Although these data indicate that enzyme potential was regulated by gene dosage and that the structural gene for each enzyme was continuously available for transcription during the cell-cycle it was not possible by using inhibitors of RNA synthesis, to demonstrate concurrent transcription during enzyme induction.
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PMID:Induction potential for glyoxylate cycle enzymes during the cell cycle of Euglena gracilis. 24 Jul

The enzyme acetylcoenzyme A synthetase (acetate-CoA ligase (AMP forming), EC 6.2.1.1) from Saccharomyces cerevisiae (baker's yeast) is used for the synthesis of 1 mumol [11C]acetylcoenzyme A. (CoA-[11C]Ac). A screening of the immobilization of the enzyme on differently derivatized controlled pore glass beads (50 nm pore size and 125-180 micron particle size) was performed. Several silanes, spacer arms and terminal reactive groups were tested. The immobilized enzyme was subjected to storage stability tests. From these experiments, the method of choice was selected: immobilization on CNBr-activated controlled pore glass. The immobilized parameters were optimized further to improve the activity of the enzyme-loaded glass beads. The latter were packed in a glass column. The kinetic properties of the column were investigated and optimized to obtain an almost complete conversion of 1 mumol acetate into acetylcoenzyme A (CoA-Ac) within a few minutes. This is realized with an enzyme reactor (13.0 x 0.5 cm) containing 6.12 U active acetylcoenzyme A synthetase immobilized onto 1 g controlled pore glass.
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PMID:Immobilization of acetylcoenzyme A synthetase and the preparation of an enzyme reactor for the synthesis of [11C]acetylcoenzyme A. 289 70

On the basis of enzyme activities detected in extracts of Selenomonas ruminantium HD4 grown in glucose-limited continuous culture, at a slow (0.11 h-1) and a fast (0.52 h-1) dilution rate, a pathway of glucose catabolism to lactate, acetate, succinate, and propionate was constructed. Glucose was catabolized to phosphoenol pyruvate (PEP) via the Emden-Meyerhoff-Parnas pathway. PEP was converted to either pyruvate (via pyruvate kinase) or oxalacetate (via PEP carboxykinase). Pyruvate was reduced to L-lactate via a NAD-dependent lactate dehydrogenase or oxidatively decarboxylated to acetyl coenzyme A (acetyl-CoA) and CO2 by pyruvate:ferredoxin oxidoreductase. Acetyl-CoA was apparently converted in a single enzymatic step to acetate and CoA, with concomitant formation of 1 molecule of ATP; since acetyl-phosphate was not an intermediate, the enzyme catalyzing this reaction was identified as acetate thiokinase. Oxalacetate was converted to succinate via the activities of malate dehydrogenase, fumarase and a membrane-bound fumarate reductase. Succinate was then excreted or decarboxylated to propionate via a membrane-bound methylmalonyl-CoA decarboxylase. Pyruvate kinase was inhibited by Pi and activated by fructose 1,6-bisphosphate. PEP carboxykinase activity was found to be 0.054 mumol min-1 mg of protein-1 at a dilution rate of 0.11 h-1 but could not be detected in extracts of cells grown at a dilution rate of 0.52 h-1. Several potential sites for energy conservation exist in S. ruminantium HD4, including pyruvate kinase, acetate thiokinase, PEP carboxykinase, fumarate reductase, and methylmalonyl-CoA decarboxylase. Possession of these five sites for energy conservation may explain the high yields reported here (56 to 78 mg of cells [dry weight] mol of glucose-1) for S. ruminantium HD4 grown in glucose-limited continuous culture.
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PMID:Pathway and sites for energy conservation in the metabolism of glucose by Selenomonas ruminantium. 314 85

1. Assessment of the overall metabolic changes in lactating mammary gland after thyroidectomy has been made by measurement of the incorporation of (14)C from specifically labelled glucose, pyruvate and acetate into (14)CO(2) and (14)C-labelled lipid in the experimental rats and in sham-operated control animals. 2. Thyroidectomy depressed the oxidation of (14)C-labelled substrates, an effect still apparent when the control rats were pair-fed with thyroidectomized rats; however, the ratio of oxidation of [1-(14)C]glucose/oxidation of [6-(14)C]glucose was unaltered. In parallel with these studies it was revealed that the activities of hexokinase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-linked isocitrate dehydrogenase were all lower in the thyroidectomized group than in the pair-fed control group. 3. Thyroidectomy also lowered the incorporation of (14)C-labelled substrates into (14)C-labelled lipid, an effect further studied by measurement of the activities of citrate-cleavage enzyme and acetate thiokinase. Restricting the food intake of the control rats to that of the thyroidectomized group lowered the activity of citrate-cleavage enzyme, but no further depression was observed on thyroidectomy. The oxidized and reduced nicotinamide nucleotide content of mammary tissue was shown to be decreased in the thyroidectomized rats compared with the control rats.
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PMID:Effect of thyroidectomy on pathways of glucose metabolism in lactating rat mammary gland. 438 95

1. The pattern of metabolism of (14)C-labelled substrates in the lobster nerve suggested a normal tricarboxylic acid cycle with a slow turnover. 2. Acetylcholine was synthesized from [2-(14)C]acetate, [2-(14)C]pyruvate and [1,5-(14)C]citrate, implying the presence of acetate thiokinase, choline acetylase and citrate-cleavage enzyme. 3. [2-(14)C]Acetate was the best precursor. 4. The formation of acetyl-CoA from citrate was limited, probably by the citrate-cleavage enzyme, although the magnitude of the reversed reactions of the tricarboxylic acid cycle was large when compared with that of the forward reactions. 5. The relative magnitude of the two pathways (acetyl-CoA and carbon dioxide fixation) in pyruvate utilization was nearly equal. 6. The probable presence of metabolic compartments in the lobster nerve is discussed.
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PMID:A study on the tricarboxylic acid cycle and the synthesis of acetylcholine in the lobster nerve. 547 73

1. The overall metabolic changes in lactating mammary gland in alloxan-diabetic and anti-insulin-serum-treated rats were assessed by measurement of the incorporation of (14)C from specifically labelled glucose, pyruvate and acetate into carbon dioxide and lipid, together with measurements of enzymes concerned with the pentose phosphate pathway and with citrate metabolism. 2. Alloxan-diabetes depressed the rate of formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose to approx. 10% of the control rate; this was partially reversed by addition of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.9 in the diabetic group and was restored to 14.3 in the presence of insulin in vitro. In keeping with these results it was shown that glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were significantly decreased in alloxan-diabetic rats. 3. Alloxan-diabetes depressed the decarboxylation and the oxidation of labelled pyruvate, but not the oxidation of labelled acetate. 4. The synthesis of lipid from specifically labelled glucose was greatly decreased, that from [2-(14)C]pyruvate was almost unchanged and that from [1-(14)C]acetate alone was increased in alloxandiabetic rats. However, the stimulation of lipid synthesis from acetate by glucose was small in the alloxan-diabetic rats compared with the controls. Insulin in vitro partially reversed all these effects. Both citrate-cleavage enzyme and acetate thiokinase activities were decreased in alloxan-diabetic rats. 5. Treatment of rats with anti-insulin serum depressed the formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose, but increased that from [6-(14)C]glucose. This was completely restored by the presence of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.8 in the anti-insulin-serum-treated group. There were no changes in the activity of glucose 6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase, but the hexokinase distribution changed and the content of the soluble fraction increased significantly. 6. The synthesis of lipid from specifically labelled glucose was depressed in anti-insulin-serum-treated rats; this effect was completely reversed by addition of insulin in vitro to the tissue slices.
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PMID:Effect of alloxan-diabetes and treatment with anti-insulin serum on pathways of glucose metabolism in lactating rat mammary gland. 569 42

Methanobacterium thermoautotrophicum growing on H2 plus CO2 as sole carbon and energy source was found to contain acetate thiokinase (Acetyl CoA synthetase; EC 6.2.1.1); Acetate + ATP + CoA leads to Acetyl CoA + AMP + PPi. The apparent Km value for acetate was 40 microM. Acetate kinase (EC 2.7.2.1) and phosphotransacetylase (EC 2.3.1.8) could not be detected. The specific activity of acetate thiokinase was high in cells grown with limited H2 and CO2 supply (approximately 100 nmol/min . mg protein), it was low in exponentially grown cells (2 nmol/min . mg protein). This corresponded with the finding that cells growing linearly in the presence of acetate assimilated the monocarboxylic acid in high amounts (greater than 10% of the cell carbon was derived from acetate), whereas exponentially growing cells did not (less than 1% of cell carbon was derived from acetate). These latter observations indicated that acetate thiokinase and free acetate are not involved in autotrophic CO2 fixation in M. thermoautotrophicum. The presence and some kinetic properties of succinate thiokinase (EC 6.2.1.5), adenylate kinase (EC 2.7.4.3), and inorganic pyrophosphatase (EC 3.6.1.1) are also described.
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PMID:Acetate thiokinase and the assimilation of acetate in methanobacterium thermoautotrophicum. 611

Phenylmethylsulfonyl fluoride (PMSF), a reagent commonly employed for the inhibition of serine proteases, has been found to cause significant inhibition of the incorporation of labeled acetate, but not mevalonate, into nonsaponifiable lipid and digitonin-precipitable sterols in the 10,000 X g supernatant fraction of rat liver homogenate preparations. In two experiments, the extent of inhibition of the synthesis of digitonin-precipitable sterols from acetate by PMSF at 1 mM was 81 and 65%. PMSF inhibited the synthesis of nonsaponifiable lipid from acetate at concentrations as low as 0.1 microM. Preincubation of the 10,000 X g supernatant fraction of rat liver homogenates with PMSF (1 mM) resulted in a significant reduction of the activities of acetate thiokinase and 3-hydroxy-3-methylglutaric acid (HMG)-CoA synthase, but did not affect the activities of acetoacetyl-CoA thiolase. Preincubation of rat liver microsomes with PMSF (1 mM) caused a 50% reduction in the level of HMG-CoA reductase activity. The combined results indicate that major sites of action of PMSF in the inhibition of sterol biosynthesis from labeled acetate appear to be on the activities of acetate thiokinase, HMG-CoA synthase, and HMG-CoA reductase. Another reagent used to inhibit serine proteases, diisopropylfluorophosphate, had (at a concentration of 1 mM) no effect on the activities of cytosolic acetoacetyl-CoA thiolase, HMG-CoA synthase, and HMG-CoA reductase.
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PMID:Effect of phenylmethylsulfonyl fluoride on sterol biosynthesis in 10,000 x g supernatant fraction of rat liver homogenates. 611 96


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