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)

The mode of action of carnitine on the growth of the yeast Torulopsis bovina ATCC 26014 was investigated. When 0.5-5 microM L-carnitine was added to the medium, the growth rate doubled for both aerobic and anaerobic cultures. Cells grown in the absence of carnitine contain 0.4 nmol of L-carnitine/g, wet weight, but with 5 microM L-carnitine in the media, cells contain 1400 nmol of carnitine/g, wet weight, by the end of exponential growth. When [1-14C]acetyl-L-carnitine was added to growth media, almost all of the radioactivity became cell-associated. Most of the 14C was incorporated into cell protein although considerable 14C was recovered in the fatty acid fraction of saponified cells. Analyses of the amino acids derived from radiolabeled protein showed that the acetyl[14C] of acetylcarnitine was in glutamate, arginine, proline, leucine, and lysine. In contrast, [1-14C]acetate labeled leucine and lysine. Isopycnic density gradient analysis demonstrated that carnitine acetyltransferase was primarily associated with mitochondria, while acetyl-CoA synthetase and acetyl-CoA hydrolase were cytosolic. Isolated mitochondria incorporated [14C]acetylcarnitine radioactivity into citrate and 2-oxoglutarate. The data are consistent with carnitine facilitating the transfer of acetyl groups from the cytosol into mitochondria for synthesis of citrate and its metabolites. These results demonstrate a role for carnitine in biosyntheses in the yeast T. bovina.
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PMID:A biosynthetic role for carnitine in the yeast Torulopsis bovina. 668 27

Two short-chain fatty acyl-CoA synthetases were extracted from the photosynthetic bacterium, Rhodopseudomonas sphaeroides, and partially purified by column chromatography on Sephacryl S-200 and DEAE-cellulose. One enzyme activated propionate, valerate, acrylate, butyrate, and acetate, and was designated as propionyl-CoA synthetase, since the highest activity and lowest Km value (0.6 mM) were observed with propionate. The other enzyme activated acetate, propionate and acrylate. It showed the highest activity and lowest Km value (0.37 mM) for acetate, and was identified as acetyl-CoA synthetase [EC 6.2.1.1].
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PMID:Short-chain acyl-coenzyme A synthetases in Rhodopseudomonas sphaeroides. 697 35

1. The mean volume of adipocytes, the rates of fatty acid and acylglycerol glycerol synthesis from various precursors (in vitro), the rates of oxidation of acetate and glucose (in vitro) and the activities of lipoprotein lipase and various lipogenic enzymes were determined for perirenal adipose tissue from foetal lambs during the last month of gestation. 2. The fall in the rate of growth of perirenal adipose tissue during the last month of gestation is associated with a diminished capacity for fatty acid synthesis and lipoprotein lipase activity, but no change in the rate of acylglycerol glycerol synthesis was observed. There was no fall in the activities of cytosolic acetyl-CoA synthetase or the NADP-linked dehydrogenases, suggesting that the decrease in the rate of fatty acid synthesis was due to an impairment at the level of acetyl-CoA carboxylase or fatty acid synthetase. 3. The rate of fatty acid synthesis from acetate was greater than that from glucose. The rate of fatty acid synthesis from glucose per adipocyte of foetal lambs was similar to that of young sheep. The characteristic metabolism of adipose tissue of the adult sheep is thus present in the foetus, despite the relatively large amounts of glucose in the foetal 'diet'.
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PMID:Aspects of adipose-tissue metabolism in foetal lambs. 703 12

Some naturally occurring pseudoguaianolides and germacranolides as well as synthetic related compounds were observed to be antihyperlipidemic agents in mice. Several of these compounds at a dose of 20 mg/kg/day resulted in lowering of serum cholesterol by approximately 30% and of serum triglycerides by approximately 25%. Thiol-bearing enzymes of lipid synthesis, i.e., acetyl-CoA, citrate-lyase, acetyl-CoA synthetase, and beta-hydroxy-beta-methylglutaryl-CoA reductase, were inhibited by these agents in vitro, supporting the premise that these agents alkylate thiol nucleophiles by a Michael-type addition. The alpha-methylene-gamma-lactone moiety, the beta-unsubstituted cyclopentenone ring, and the alpha-epoxycyclopentanone system of these compounds appeared to be responsible for the lowering of serum lipids.
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PMID:Antihyperlipidemic activity of sesquiterpene lactones and related compounds. 720 85

1. The lipogenic enzyme ATP citrate lyase (ATP:citrate oxaloacetate-lyase (pro-3S-CH2COO-acetyl-CoA; ATP-dephosphorylating), EC 4.1.3.8) is partially purified from human liver by ammonium sulfate fractionation and anionexchange chromatography. 2. Km values for the substrates are 1.1 x 10(-5) 1.3 x 10(-3), and 1.2 x 10(-4) M for CoASH, ATP and citrate, respectively. The hypolipidemic drug L(-)-hydroxycitrate is a competitive inhibitor with respect to citrate (Ki = 3 x 10(-4) M). 3. Specific activities measured in liver, adipose tissue and intestinal mucosa (autopsic and biopsic material) are in the range of 1 mU/mg protein suggesting that the citrate pathway does not significantly contribute to human lipogenesis. No stimulation is found after a 3-day carbohydrate-rich diet. 4. Specific activities of other key-enzymes of the acetyl-CoA production from carbohydrates (pyruvate dehydrogenase, cytosolic acetyl-CoA synthetase) are of the same low magnitude.
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PMID:Properties and organ distribution of ATP citrate (pro-3S)-lyase. 741 78

Highly purified rat liver fatty acid synthetase is completely inhibited when assayed in the presence of a coenzyme A-depleting system such as that catalyzed by phosphotransacetylase, acetyl-CoA synthetase, or ATP citrate lyase. The addition of free CoA causes a reversal of this inhibition. The requirement of free CoA is the same whether acetyl-CoA or butyryl-CoA serves as the primer for fatty acid synthetase. The CoA-depleted and thus inactive fatty acid synthetase system can be reactivated by the addition of a rat brain thioesterase or a rat mammary gland thioesterase II preparation. This reactivation appears to occur in the absence of free CoA. Long chain fatty acids (mainly palmitate) are formed by the thioesterase reactivated system. These results suggest that CoA is required for the termination of the fatty acid synthetase reaction. Possible mechanisms are discussed.
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PMID:Coenzyme A requirement for the termination reaction of rat liver fatty acid synthetase. 743 Jan 43

Previous studies of Arthrobacter pyridinolis indicated that during the first half of the growth cycle on D-fructose, the organism utilizes a respiration-coupled transport system and exhibits glyoxylate pathway activity; during the second half of the growth cycle, a phosphoenolypyruvate:D-fructose phosphotransferase system is used for transport and no glyoxylate pathway activity is found [Pelliccione et al. (1979) Eur. J. Biochem. 95, 69--75]. A citrate-synthase-deficient mutant had the following properties: (a) high constitutive levels of glyoxylate pathway enzymes on various substrates, while such levels were only found in the wild type when it was grown on acetate; (b) acetyl-CoA levels much higher than in the wild type grown on several different substrates, whereas other metabolite levels were similar in the two strains; and (c) under conditions for induction of the phosphotransferase system, the wild type exhibited at least twice as much phosphotransferase activity as the mutant strain. A mutant lacking acetyl-CoA synthetase exhibited no induction of the glyoxylate pathway in the presence of acetate, although acetate uptake was normal. The results indicate a role for acetyl-CoA as inducer of the glyoxylate pathway. They further suggest a possible role, perhaps indirect, in repression of the phosphotransferase system.
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PMID:A deficiency of citrate synthase results in constitutive expression of the glyoxylate pathway in Arthrobacter pyridinolis. 746 Sep 50

During batch growth of Alcaligenes eutrophus on benzoate-acetate mixtures, benzoate was the preferred substrate, with acetate consumption being delayed until the rate of benzoate consumption had diminished. This effect was attributed to a transcriptional control of the synthesis of acetyl coenzyme A (acetyl-CoA) synthetase, an enzyme necessary for the entry of acetate into the central metabolic pathways, rather than to a biochemical modulation of the activity of this enzyme. Analysis of a 2.4-kb mRNA transcript hybridizing with the A. eutrophus acoE gene confirmed this repression effect. In a benzoate-limited chemostat culture, derepression was observed, with no increase in the level of expression following an acetate pulse. Benzoate itself was not the signal triggering the repression of acetyl-CoA synthetase. This role was played by catechol, which transiently accumulated in the medium when high specific rates of benzoate consumption were reached. The lack of rapid inactivation of the functional acetyl-CoA synthetase after synthesis has been stopped enables A. eutrophus to retain the capacity to metabolize acetate for prolonged periods while conserving minimal protein expenditure.
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PMID:Acetate utilization is inhibited by benzoate in Alcaligenes eutrophus: evidence for transcriptional control of the expression of acoE coding for acetyl coenzyme A synthetase. 759 30

In Escherichia coli carrying the poly(3-hydroxyalkanoate) (PHA) biosynthesis pathway on a plasmid (pha+), the function of the ackA (acetate kinase) and pta (phosphotransacetylase) genes is necessary for efficient incorporation of 3-hydroxyvalerate (3-HV) into the copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)). Recombinant pha+ E. coli fadR atoC(Con) strains possessing mutations in ackA, pta, or both ackA and pta exhibited substantially reduced levels of 3-HV formation. Conversely, the same strains carrying the ackA gene on a multicopy plasmid exhibited an increase in 3-HV formation concomitant with a large increase in acetate kinase activity. However, if the strain possessing the multicopy ackA+ plasmid was mutant at the pta locus, it lost the ability to incorporate significant amounts of 3-HV into P(3HB-co-3HV). In addition to the ackA pta pathway, there is an inducible activity that can also mediate the incorporation of 3-HV into P(3HB-co-3HV). This pathway is repressed by glucose and is not normally operative in P(3HB-co-3HV) production in recombinant pha+ E. coli strains that are grown using glucose as the major carbon source. It appears likely that this activity is due to an inducible acetyl-CoA synthetase that converts propionate to propionyl-CoA.
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PMID:The function of ackA and pta genes is necessary for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in recombinant pha+ Escherichia coli. 760 63

Two nuclear genes, RTG1 and RTG2, which sense the functional state of yeast mitochondria, have been described recently. Yeast strains with null alleles of either of these two genes (delta rtg1, delta rtg2) cannot grow on acetate as the sole carbon source and are auxotrophic for glutamate and aspartate. We report here a series of metabolic experiments and enzyme activity measurements that were made in an attempt to determine the reason for the acetate- phenotype and the glutamate/aspartate auxotrophy. Decreases in the activities (approximately 50%) in mitochondrial citrate synthase (CS1), acetyl-CoA synthetase, NAD isocitrate dehydrogenase, and pyruvate carboxylase were noted. When CS1 was overexpressed in the delta rtg1 and delta rtg2 mutants, these strains could grow on acetate but were still auxotrophic for glutamate/aspartate. We propose that, in the mutant strain, CS1 activity becomes limiting for efficient acetate utilization, but that other complex metabolic interactions are affected, limiting production of intermediates that would allow synthesis of glutamic and aspartic acids.
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PMID:Enzymatic and metabolic studies on retrograde regulation mutants of yeast. 772 18


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