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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)

Mutants of Escherichia coli K12 have been isolated that grow on media containing pyruvate of proline as sole carbon sources despite the presence of 10 or 50 mM-sodium fluoroacetate. Such mutants lack either acetate kinase [ATP: acetate phosphotransferase; EC 2.7.2.1] or phosphotransacetylase [acetyl-CoA: orthophosphate acetyltransferase; EC 2.3.1.8] activity. Unlike wild-type E. coli, phosphotransacetylase mutants do not excrete acetate when growing aerobically or anaerobically on glucose; their anaerobic growth on this sugar is slow. The genes that specify acetate kinase (ack) and phosphotransacetylase (pta) activities are cotransducible with each other and with purF and are thus located at about min 50 on the E. coli linkage map. Although Pta- and Ack- mutants are greatly impaired in their growth on acetate, they incorporate [2-14C]acetate added to cultures growing on glycerol, but not on glucose. An inducible acetyl-CoA synthetase [acetate: CoA ligase (AMP-forming); EC 6.2.1.1] effects this uptake of acetate.
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PMID:The enzymic interconversion of acetate and acetyl-coenzyme A in Escherichia coli. 2 41

Formation of acetyl-CoA through acetyl-CoA synthetase (forward reaction) and through choline acyltransferase (backward reaction) was investigated in tissue extract from the electric organ of Torpedo marmorata. When the tissue extract was submitted to gel filtration on Sephadex G-25, the formation of acetyl-CoA by acetyl-CoA synthetase appeared fully dependent on ATP and CoA and partially dependent on acetate (an endogenous supply of acetate is discussed). Choline acetyltransferase was a potent source of acetyl-CoA, only requiring acetylcholine and CoA, and was much more efficient than acetyl-CoA synthetase for concentrations of acetylcholine likely to be present in nerve endings.
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PMID:Biosynthesis of acetyl-coenzyme A in the electric organ of Torpedo marmorata in relation to acetylcholine metabolism. 2 1

The purified alpha-thiophosphate diastereoisomers of adenosine 5'-(1-thio)-triphosphate were used to study the stereochemical course of the reaction catalyzed by yeast acetyl-CoA synthetase. Asymmetrically labeled adenosine 5'-thiophosphate was formed from the "B" diastereoisomer of adenosine 5'-(1-thio)-triphosphate and [18O]acetate. The label was found to be in the opposite orientation from the leaving pyrophosphate group showing that the acetate activation step occurred with inversion of configuration at the alpha-phosphorus.
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PMID:The stereochemical course of acetate activation by yeast acetyl-CoA synthetase. 2 94

A method is shown to be effective over a wide range of enzyme ratios for the simultaneous detection of the two isoenzymes of acetyl coenzyme A synthetase [acetate:coenzyme A ligase (AMP-forming); EC 6.2.1.1] in homogenates and cellular fractions of Saccharomyces cerevisiae. When this method was used, it was found that cells grown under anaerobic conditions contained only one variety of this enzyme, designated the nonaerobic synthetase, whereas cells grown with vigorous aeration contained principally the other, aerobic, synthetase. In cells grown as standing cultures (i.e., semi-aerobically), both enzymes were present and were found mainly in the extramitochondrial material of homogenates. When anaerobic cultures were aerated, the amount of aerobic enzyme increased steadily over a 24-h period, so that at the end of this time, aerated cells contained predominantly aerobic enzyme. During this same period, the amount of nonaerobic enzyme decreased. The percentage of aerobic enzyme that sedimented with the mitochondria increased steadily during this period of aeration, so that, at the end of 24 h of aeration, essentially all of the aerobic enzyme sedimented with the mitochondria. The nonaerobic enzyme was never found in this cellular compartment.
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PMID:Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae. 3 46

Acetyl-CoA synthetase (EC 6.2.1.1) was assayed in subcellular fractions of rabbit liver homogenates. The activity was located almost exclusively in the cytosol. There was no decrease in activity when butyrate or propionate (each at 5--20 mM) were added to the assay medium.
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PMID:Rabbit liver acetyl-CoA synthetase. 3 61

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.
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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.
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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.
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PMID:Oxygen as a factor in eukaryote evolution: some effects of low levels of oxygen on Saccharomyces cerevisiae. 4 Dec 5

The changes in the immunological indices characterizing the T and B immunity system and also in biological resistance of atherosclerosis patients were studied under conditons of the use of the antireticular cytotoxic serum microdoses. A possibility of employing the ACS for stimulation of the immune system was demonstrated.
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PMID:[Antireticular cytotoxic serum as an agent for stimulating the immunity system]. 8

13 cases of ACS are presented: seven of them were identified as Apert's syndrome; two as Chotzen's syndrome; three as Carpenter's syndrome, and one as Pfeiffer's syndrome. These disorders have no known ethiology. However, it is necessary to look for diabetic antecedents and dermatogliphus alterations, both in the patient and the parents. An attempt to give an explanation of their hereditary penetrance is made. Frequency of associated abnormalities, mental retardation, therapeutics, prognosis, and recent encouraging results of plastic surgery of the face are reviewed.
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PMID:[Acrocephalosyndactyly (ACS) (author's transl)]. 17 68


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