Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.1 (ACS)
 78,556 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative metabolism in the in vivo canine myocardium was studied noninvasively using 13C-enriched acetate and non-steady state 13C NMR techniques. Under low workload conditions, the myocardium oxidized the infused [2-13C]acetate and incorporated the labeled carbon into the glutamate pool as expected. This conclusion stems from the rapid enrichment of the C-2, C-3, and C-4 carbons of glutamic acid both under in vivo conditions and in extracts. Surprisingly, [2-13C]acetate uptake was not observed at high workloads as reflected by an absence of glutamate pool enrichment at these rate pressure products. Rather, the myocardium selected its substrate from an endogenous pool. Since free acetate can directly cross the inner mitochondrial membrane and be converted to acetyl-CoA through acetyl-CoA synthetase, these results support workload-dependent regulation of substrate access to the mitochondrial CoASH pool. As such, we advance the hypothesis that the selection of substrate for condensation with CoASH and subsequent oxidation in the tricarboxylic acid cycle is regulated kinetically through the Km values of the appropriate condensation enzymes and through the absolute levels of free CoASH in the mitochondria.
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PMID:Dynamic 13C NMR analysis of oxidative metabolism in the in vivo canine myocardium. 825 51

The mutant gene coding for a proline-activating domain (grs2-pro) was cloned and sequenced from Bacillus brevis Nagano, BII-3 strain, which produces gramicidin S synthetase 2 defective in proline-activation. By comparison of the nucleotide sequence with the wild-type sequence, a single point mutation was found at the 2609th guanine, which was replaced with adenine, resulting in the change of the 870th glycine to glutamic acid. Homology search for the deduced amino acid sequence of grs2-pro gene revealed that the 870th glycine was conserved in adenylate-forming enzymes, and its flanking sequence was highly conserved among the aminoacyl adenylate-forming enzymes, such as antibiotic peptide synthetases: gramicidin S synthetase 1 and 2 (GS1, GS2), tyrocidine synthetase 1 (TS1), and delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS); and other aminoacyl adenylation enzymes: alpha-aminoadipate reductase (LYS2), EntF, and AngR. On the other hand, this flanking sequence was not conserved in the other adenylate-forming enzymes lacking amino acid activation, such as acetyl-CoA synthetase, long-chain acyl-CoA synthetase, luciferase, and 4-coumarate CoA ligase. Single base substitutions at the 870th GGG codon were carried out by oligonucleotide site-directed mutagenesis. Four mutagenized clones were isolated, containing grs2-pro genes which exchange 870-Gly for alanine, valine, arginine, and tryptophan. The translated products from these clones could scarcely catalyze proline-dependent ATP-32PPi exchange reaction. The coil structure of 870-Gly region was lost in the mutants. These results suggest that the 870-Gly residue of grs2-pro protein is essential for aminoacyl-adenylation in the antibiotic peptide synthetase family.
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PMID:Effect of single base substitutions at glycine-870 codon of gramicidin S synthetase 2 gene on proline activation. 827 62

Significant hypolipidemic activity was demonstrated by 6-ethoxycarbonyl-1-3-phenyl-1,3,5-triazabicyclo[3.1.0]hexane-2,4-dione, 2-ethoxycarbonyl-5-phenyl-1,3,5-triazine-4,6(1H,5H)-dione and 2-ethoxycarbonyl-5-(4-chlorophenyl)-1,3,5-triazine-4,6(1H,5H)-dione in rodents at 20 mg/kg/day. These agents lowered serum cholesterol and triglyceride levels by approximately 40% in mice after 16 d. Tissue lipids in rat liver, small intestinal mucosa, aortic wall and feces were reduced by treatment with the agents. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol levels were reduced in the rat; high density lipoprotein (HDL) cholesterol levels were elevated after 14 d of treatment. The activities of regulatory enzymes, e.g., acetyl-CoA synthetase, acyl-CoA:cholesterol acyltransferase, cholesterol 7 alpha-hydroxylase, sn-glycerol-3-phosphate acyltransferase, phosphatidylate phosphohydrolase and heparin-induced lipoprotein lipase, involved in de novo synthesis of hepatic lipids were affected by the agents. The new compounds may represent another class of potentially useful hypolipidemic agents for the treatment of atherosclerosis since HDL cholesterol levels were increased and VLDL and LDL cholesterol levels were lowered by some of the agents.
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PMID:Hypolipidemic activity of 6-alkoxycarbonyl-3-aryl-1,3,5- triazabicyclo[3.1.0]hexane-2,4-diones and 2-alkoxycarbonyl-5-aryl-1,3,5-triazine-4,6(1H,5H)-diones in rodents. 846 53

Prodigiosin 25-C had little effect on DNA, RNA, and protein synthesis, and cellular ATP content, but the drug markedly inhibited the incorporation of acetate into lipid fractions. Under the same conditions, the incorporation of other lipid precursors including glycerol, mevalonate, palmitate, and oleate was not affected. A decrease in the incorporation of acetate was not due to the inhibition of fatty acid biosynthesis, because prodigiosin 25-C did not affect the activity of acetyl-CoA synthetase, acetyl-CoA carboxylase or fatty acid synthase in cell-free assay systems prepared from rat liver cytosol. In contrast, prodigiosin 25-C strongly inhibited the rapid uptake of acetate into acid-soluble fraction in intact cells. The results suggest that prodigiosin 25-C specifically perturbs the permeation of acetate through plasma membranes.
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PMID:Prodigiosin 25-C perturbs permeation of acetate in a cultured cell line. 853 81

Giardia lamblia, an amitochondriate eukaryote, contains acetyl-CoA synthetase (ADP-forming), an enzyme known only from one other eukaryote (Entamoeba histolytica) and a few anaerobic prokaryotes. The enzyme has been purified about 350-fold. The activity in the direction of acetate formation was dependent on ADP and inorganic phosphate. The reverse reaction could not be detected. Succinyl-CoA, propionyl-CoA and dADP were utilized with lower efficiency. The enzyme did not utilize AMP plus PPi thus differs from the broadly distributed acetyl-CoA synthetase (AMP-forming). The enzyme is responsible for acetate production accompanied by ATP generation, thus plays an important role in G. lamblia metabolism.
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PMID:Purification and characterization of the acetate forming enzyme, acetyl-CoA synthetase (ADP-forming) from the amitochondriate protist, Giardia lamblia. 855 9

Simultaneous utilization of glucose and ethanol by the yeast Schizosaccharomyces pombe CBS 356 was studied in aerobic chemostat cultures. In glucose-limited cultures, respirofermentative metabolism occurred at growth rates above 0.16 h-1. Although Sch. pombe lacks a functional glyoxylate cycle and therefore cannot utilize ethanol as a sole carbon source, ethanol was co-consumed by glucose-limited chemostat cultures. As a result, biomass yields increased, but not up to the theoretical value [0.92 g biomass (g glucose)-1] expected if all of the acetyl-CoA produced from glucose was instead synthesized from ethanol. When ethanol accounted for more than 30% of the substrate carbon in the mixed feed, it was incompletely utilized. In mixed-substrate cultures with a saturating ethanol fraction in the feed, the increase of the biomass yield as a result of ethanol consumption was highest at low dilution rates. This was not due to an increased specific rate of ethanol consumption at low growth rates; rather, the longer residence times at low dilution rates allowed Sch. pombe to utilize a larger fraction of the available ethanol, part of which was oxidized to acetate. Activities of gluconeogenic and glyoxylate-cycle enzymes were not detected in cell-free extracts of any of the cultures. Activities of acetaldehyde dehydrogenase and acetyl-CoA synthetase were low and of the same order of magnitude as the in vivo rates of acetate activation to acetyl-CoA. The results show that ethanol is a poor substrate for Sch. pombe, even as an auxiliary energy source.
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PMID:Metabolic fluxes in chemostat cultures of Schizosaccharomyces pombe grown on mixtures of glucose and ethanol. 870 80

Nine mutants of the filamentous fungus Phycomyces blakesleeanus have been isolated on the basis of their resistance to fluoroacetate. None of the isolates uses acetate as the sole carbon source. Genetic complementation experiments revealed that all the mutants belong to the same complementation group. Biochemical analysis indicated that the acetate-induced acetyl-CoA synthetase activity is abolished in all nine mutants, thus suggesting that they are affected in the gene coding for acetyl-CoA synthetase (facA).
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PMID:Mutants of Phycomyces blakesleeanus Defective in Acetyl-CoA Synthetase 881 87

High rates of methanogenesis from acetate and ATP were observed from cell-free extracts of the thermophilic acetotrophic methanogen Methanothrix (Methanosaeta) thermophila strain CALS-1 when cultures were grown in a pH auxostat fed with acetic acid. Specific methanogenic activities ranged from 50-300 nmol min-1 (mg protein)-1, which was comparable to those for whole cells. In contrast to results with Methanosarcina spp., the reaction did not require high levels of H2 in the headspace. CO was inhibitory to methanogenesis from acetate. The inhibition by CO and the lack of effect of H2 on methanogenesis from acetate resemble previous results with whole cells of CALS-1. Protein concentrations in extracts > 5 mg/ml were required for good activity, and the optimum temperature for the methanogenesis was near 65° C. ATP was required in substrate quantities and was converted mainly to AMP. The maximum CH4/ATP stoichiometry obtained was near 1.0, consistent with acetate activation using an acetyl-CoA synthetase mechanism that converts ATP to AMP and pyrophosphate. Methanogenesis in extracts was inhibited by bromoethane sulfonate and cyanide, indicating the involvement of methylcoenzyme M methylreductase and a carbon monoxide dehydrogenase complex with methanogenesis from acetate. These results are consistent with acetyl-coenzyme A (CoA) as the form of activated acetate involved in methanogenesis from acetate in strain CALS-1, but no activity could be obtained from extracts using acetyl-CoA as a substrate.
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PMID:Methanogenesis from acetate by cell-free extracts of the thermophilic acetotrophic methanogen Methanothrix thermophila CALS-1 882 51

This paper describes a spectrophotometric assay that can measure the inorganic pyrophosphate produced from various enzymatic reactions. This is a coupled assay in which the addition of inorganic pyrophosphatase initially cleaves the pyrophosphate into two molecules of phosphate. The phosphate is then detected by the conversion of 2-amino-6-mercapto-7-methylpurine ribonucleoside to 2-amino-6-mercapto-7-methylpurine by purine nucleoside phosphorylase [M.R. Webb (1992) Proc. Natl. Acad. Sci. USA 89, 4884-4887]. The reaction is monitored by measuring the increase in absorbance at 360 nm. The generation of two molecules of phosphate from each molecule of pyrophosphate increases the sensitivity of the assay, which has a linear range from about 1 to 75 nmol pyrophosphate in a 1-ml reaction volume. To demonstrate the general usefulness of this assay, we show that the inorganic pyrophosphate generated by reactions involving acetyl-CoA synthetase and luciferase can be readily detected and that continuous as well as end-point assays can be performed.
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PMID:A spectrophotometric method to measure enzymatic activity in reactions that generate inorganic pyrophosphate. 895 23

Two independent pathways in Escherichia coli convert acetate to acetyl CoA: reversal of acetate production by phosphotransacetylase and acetate kinase, and the acetyl-CoA synthetase (Acs) pathway that scavenges acetate. We investigated acs gene expression by using a cat transcriptional fusion. It was observed that acs expression varies depending on the carbon sources used and occurs in the stationary phase of growth even in the absence of acetate. Mutations in iclR for the repressor of the glyoxylate shunt and in rpoS for the stationary phase sigma factor reduced the consumption of acetate mediated by Acs, indicating that both are involved in acs regulation.
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PMID:Involvement of iclR and rpoS in the induction of acs, the gene for acetyl coenzyme A synthetase of Escherichia coli K-12. 899 13


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