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

Adenosine 5'-(thiophosphate) AMPS) contains a prochiral phosphorus center. Differentiation of the two diastereotopic oxygens would allow elucidation of the stereochemical course of biological adenylyl transfer reactions. A general method was developed to distinguish between the "pro-R" and "pro-S" oxygens. When we converted the AMPS to the isomer A of adenosine 5'-(1-thiotriphosphate) (ATPalphaS), which is known to have S configuration at Palpha, the pro-R oxygen is incorporated into the bridge position, whereas the pro-S oxygen is located at the nonbridge position. The 31P NMR spectra of the 17O-enriched compounds were used to distinguish between the bridge and nonbridge oxygens based on the decrease in the peak intensity of 31P NMR signals caused by the directly bound 17O isotope. The method was used to elucidate the stereochemical course of acetate activation catalyzed by yeast acetyl coenzyme A (CoA) synthetase. The results indicate that yeast acetyl-CoA synthetase is specific for the isomer B of ATPalphaS and that the nucleophilic displacement proceeds with net inversion of configuration at Palpha of ATPalphaS (B), supporting the "in-line" mechanism.
 ...
PMID:Use of phosphorus-31 nuclear magnetic resonance to distinguish bridge and nonbridge oxygens of oxygen-17-enriched nucleoside triphosphates. Stereochemistry of acetate activation by acetyl coenzyme A synthetase. 3 27

The present communication reports data on the lipid biosynthesis of Ehrlich ascites tumor cells grown in culture media supplemented with modified sera. Whereas the metabolisms of [14C]pyruvate and [14C]mevalonate are identical in all media tested, the incorporation of [14C] acetate is higher in medium with dialyzed serum than in medium with delipidized serum; it is suppressed in the absence of all lipids in culture medium. Cellular integrity is not impaired in modified media. The results indicate that acetyl-CoA synthetase of Ehrlich ascites tumor cells is not regulated by exogenous lipids as is known to be the case in nonmalignant cells.
 ...
PMID:Unexpectedly low incorporation of isotopic acetate into lipids of Ehrlich ascites tumor cells cultured in lipid-poor medium. 3 70

A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03% (v/v) oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth, was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth, was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.
 ...
PMID:Oxygen as a factor in eukaryote evolution: some effects of low levels of oxygen on Saccharomyces cerevisiae. 4 Dec 5

Purple sulfur (Ectothiorhodospira shaposhnikovii, Chromatium minutissimum, Lamprobacter modestohalophilus, Thiocapsa roseopersicina) and nonsulfur (Rhodospirillum rubrum, Rhodopseudomonas palustris, Rhodopseudomonas spheroides) bacteria are capable of forming acetyl-CoA synthetase, phosphotransacetylase and acetokinase independent of the medium composition and growth conditions. In all of the purple sulfur bacteria with an exception of E. shaposhnikovii, the activity of acetokinase is much higher than in purple nonsulfur bacteria. Apart from being involved in the synthesis of acetyl-CoA, such enzymes as phosphotransacetylase, acetokinase and adenylate kinase may play an important role in energy processes of some purple bacteria in the dark.
 ...
PMID:[Possible pathways for acetyl-CoA formation by purple bacteria]. 22 68

The synthesis of a new coenzyme A analogue, N6-[N-(6-aminohexyl)carbamoylmethyl]-CoA, suitable for immobilisation through its terminal amino group to support matrices, is described. The synthetic route starts with bis(CoA) and involves the following steps: alkylation with iodoacetic acid and rearrangement yielding bis(N6-carboxymethyl-CoA), elongation of the carboxymethyl terminal with 1,6-diaminohexane using carbodiimide to yield bis(N6-[N-(6-aminohexyl)-carbamoylmethyl]-CoA) and finally the splitting of this bis[CoA analogue) through reduction with dithiothreitol to give the final product in approximately 10% overall yield. This CoA analogue showed 'coenzymic activity' with the enzymes acetyl-CoA synthetase, phosphotransacetylase and succinic thiokinase. Covalent binding of the CoA analogue to Sepharose 4B was normally carried out using its S-(5-thio-2-nitrobenzoic acid) derivative as this allows a convenient way for determining the amount of ligand coupled, based on the amount of 5-thio-2-nitrobenzoic acid liberated from the gel after reduction with dithiothreitol. After covalent binding of the CoA analogue to water-soluble activated dextran 70, the analogue was recycled while present in an ultrafiltration cell using the enzymes phosphotransacetylase and citrate synthase. The reaction was followed by measuring the citrate formed on addition of acetylphosphate and oxaloacetate. In affinity chromatographic studies it was shown that the CoA-Sepharose preparation could bind the CoA-dependent enzymes citrate synthase and succinic thiokinase and these could be biospecifically eluted using soluble CoA.
 ...
PMID:N6-[N-(6-Aminohexyl)carbamoylmethyl]-coenzyme A. Synthesis and application in affinity chromatography and as an immobilized active coenzyme. 57 88

Thirteen chromosomal loci have been identified which affect acetate metabolism in Coprinus. Mutants at only two loci, acu-l and acu-7, are deficient in isocitrate lyase (ICL) (EC 4.1.3.1) activity. acu-1 mutants are unable to induce ICL because they lack acetyl-CoA synthetase which is required to convert acetate to the metabolic inducer of ICL. acu-7 is the structural gene for ICL. This was shown by selecting temperature sensitive acu+ revertants resulting from a second mutation within the acu-7 gene. One such revertant was shown to produce an ICL protein which was more thermolabile than the wild type enzyme. Other workers have postulated that ICL activity is important during asexual morphogenesis in fungi. No evidence was found for this in Coprinus. The morphological mutant oidial, which produces abundant asexual spores even in submerged culture, had the same low uninduced level of ICL activity as the wild type. Moreover, an acu-7 mutation had no effect on the expression of the oidial phenotype.
 ...
PMID:Genetics and function of isocitrate lyase in Coprinus. 60 Feb 68

Methods are described for the direct optical assay of citrate, acetate, and acetoacetate production by isolated, incubated rat liver mitochondria. Each metabolite is converted into acetyl-CoA, using ATP: citrate lyase or acetyl-CoA synthetase or acetoacetyl-CoA synthetase and acetyl-CoA acetyltransferase, respectively. Arylamine acetyltransferase acts as auxiliary enzyme. It was shown that isolated rat liver mitochondria produce citrate, acetate and acetoacetate, and that production rates are stimulated by pyruvate and hexanoate. It was concluded that these three products might contribute to the transport of acetyl units across the mitochondrial membrane and thus serve as precursors in fatty acid synthesis. The rate of acetyl transfer does not seem to be rate-limiting with regard to the overall-process of fatty acid synthesis from carbohydrates.
 ...
PMID:Transfer of C2-units across the mitochondrial membrane. Direct recording of citrate, acetate and acetoacetate production rates. 66 82

In the liver of adult diabetics, the activity of two enzymes of the citrate-cleavage pathway was increased, the change being statistically significant for NADP-malate dehydrogenase (+ 46%, p less than 0.05) but not significant for ATP citrate-lyase (+ 55%, p greater than 0.10). The increased activity of NADP-malate dehydrogenase, together with the previously described elevation of pentose cycle dehydrogenases, suggests enhanced NADPH generation. Considering the recently proposed possibility of extramitochondrial acetyl-CoA formation by routes other than the citrate-cleavage (i.e., via cytoplasmic acetyl-CoA synthetase), our data is consistent with the occurrence of increased lipogenetic capacity.
 ...
PMID:Enzymes of citrate-cleavage pathway in liver of subjects with adult-onset diabetes. 83 95

In order to assess the extent to which metabolism within the sheep placenta may influence the transfer of metabolites between mother and foetus at different stages of gestation the activities of enzymes concerned with some aspects of carbohydrate, amino acid and keton body metabolism were determined in placental cotyledons resected from ewes during the last three months of pregnancy. The activities of pyruvate kinase (EC 2.7.1.40), lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37), ATP citrate (pro-3S)-lyase (EC 4.1.3.8), citrate (si)-synthase (EC 4.1.3.7), acetyl-CoA synthetase (EC 6.2.1.1), acetyl-CoA acetyltransferase (EC 2.3.1.9) and 3-keto acid CoA-transferase (EC 2.8.3.5) per gram wet weight cotyledon do not change during the period studied. The activities of alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.1), isocitrate dehydrogenase (NADP+) (EC 1.1.1.42), ornithine-oxoacid aminotransferase (EC 2.6.1.13) and 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) show an increase in activity between the third and fourth months of pregnancy whilst the activities of arginase (EC 3.5.3.1) and possibly pyruvate carboxylase (EC 6.4.1.1) show an increase in activity between the fourth and final months of pregnancy. Ornithine decarboxylase (EC 4.1.1.17) activity declines to one tenth of its activity during this later period. The absence of detectable activities of phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and ornithine carbamoyltransferase (EC 2.1.3.3) indicate that gluconeogenesis and urea synthesis from ammonia do not occur in the sheep placenta. It appears that the ability of the placenta to metabolise several substrates is achieved by the time the placenta reaches its maximum size at approximately 90 days.
 ...
PMID:Enzyme activities in the sheep placenta during the last three months of pregnancy. 84 73

1. The ATP dependent acetyl-, propionyl- and butyryl-CoA synthetase activities were measured in the soluble fraction of both guinea-pig heart and liver mitochondria. 2. When measured in 300 mM Tris-HC1, the V of propionate activation in heart (equals 892 munits/mg protein) is much higher than the V of acetate (equals 637 munits/mg protein) and butyrate activation (equals 143 munits/mg protein. Fatty acid competition experiments, however, clearly show that most of the propionate activation (Km equals 7.94 mM) is caused by the acetyl-CoA synthetase (EC 6.2.1.1) (Km for acetate equals 0.8 mM), while the remaining activity is probably caused by a butyryl-CoA synthetase (Km for butyrate equals 0.83 mM). This indicates that in guinea-pig heart the presence of a distinct propionyl-CoA synthetase is very unlikely. 3. In liver a completely different pattern of short-chain fatty acid activation is found: low acetate activation and moderate propionate and butyrate activation. Substrate competition experiments and kinetics of fatty acid activation indicate that in this tissue a distinct propionyl-CoA synthetase is present with high affinity for propionate (Km equals 0.6 mM) and some affinity towards acetate and butyrate (Km values respectively 11 mM and 5.4 mM).
 ...
PMID:The activation of short-chain fatty acids by the soluble fraction of guinea-pig heart and liver mitochondria. The search for a distinct propionyl-CoA synthetase. 112 7


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>