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)

Acetyl-coenzyme A synthetase (EC 6.2.1.1) activity of Saccharomyces cerevisiae was determined by a radioactive assay procedure. The activity in vitro was inhibited significantly by NADPH, NADH, or AMP and to a lesser extent by NADP, NAD, or ADP. Glutamic acid and alpha-ketoglutaric acid were not inhibitory. The enzyme level was repressed when the cells were grown in a complex nutrient medium as opposed to the minimal medium. However, a glutamic acid auxotroph glul, when grown in excess glutamic acid, demonstrated a fivefold increase of acetyl-CoA synthetase.
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PMID:Regulation of acetyl-CoA synthetase of Saccharomyces cerevisiae. 0 41

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.
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PMID:Enzymes of citrate-cleavage pathway in liver of subjects with adult-onset diabetes. 83 95

Enzymatic systems of hepatic hyperlipogenesis supply by substrate (acetyl-CoA) and cofactors (NADPH and ATP) were studied in experiments on diabetic C57Bl/Ks J mice (db/db) that served as a model of non-insulin dependent diabetes. The rise in acetyl-CoA synthetase activity catalyzing the primary step of lipogenesis from acetate has been found, while pyruvate dehydrogenase complex activity did not differ from the control and ATP-citrate lyase activity was lowered. Hyperlipogenesis in non-insulin dependent diabetes was induced by the activation of cellular energy supply revealed in enhanced 2-oxoglutarate dehydrogenase activity and elevated ATP level, as well as changes in the activity ratio of NADPH supply and utilization and the rise in fructose-1,6-diphosphate, allosteric effector of fatty acid synthetase, which resulted in the increase of the enzyme activity and created wider potentials of NADPH utilization as a reducing equivalent in lipogenesis.
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PMID:[Enzyme systems of the substrate and cofactor supply of hyperlipogenesis in non-insulin-dependent diabetes]. 289 64

1. Mammary-tissue biopsies were obtained from multiparous cows at 30 and 7 days pre partum and 7 and 40 days post partum. Investigations of the effect of lactogenesis on fatty acid and lactose synthesis involved measurements of biosynthetic capacity (tissue-slice incubations in vitro) and activities of relevant enzymes. 2. Fatty acid synthesis from acetate increased over 20-fold from 30 days pre partum to 40 days post partum. Changes in the lipogenic capacity of mammary-tissue slices more closely paralleled increases in the activities of acetyl-CoA carboxylase (EC 6.4.1.2) and acetyl-CoA synthetase (EC 6.2.1.1) than of other enzymes involved in acetate incorporation into fatty acids or in NADPH generation. 3. Lactose biosynthesis by mammary-tissue slices, lactose synthetase activity (EC 2.4.1.22) and alpha-lactalbumin concentration were all negligible at 30 days pre partum but increased 2.5-4-fold between 7 days pre partum and 40 days post partum. Phosphoglucomutase (EC 2.7.5.1), UDP-glucose pyrophosphorylase (EC 2.7.7.9) and UDP-glucose 4-epimerase (EC 5.1.3.2) had substantial activities at 30 days pre partum and increased less dramatically during lactogenesis. 4. Results are consistent with acetyl-CoA carboxylase and perhaps acetyl-CoA synthetase representing the regulatory enzyme(s) in fatty acid synthesis, with lactose synthetase (alpha-lactalbumin) serving a similar function in lactose biosynthesis.
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PMID:Metabolic adaptations during lactogenesis. Fatty acid and lactose synthesis in cow mammary tissue. 414 47

Cells of the aerotolerant anaerobe Giardia lamblia respire in the presence of oxygen. Endogenous respiration is stimulated by glucose but not by other carbohydrates and Krebs cycle intermediates. Endogenous and glucose-stimulated respiration are insensitive to cyanide, malonate, and 2,4-dinitrophenol, but are inhibited by atabrin and iodoacetamide. G. lamblia produces ethanol, acetate and CO2 both aerobically and anaerobically either from endogenous reserves or exogenous glucose. Molecular hydrogen is not produced. The following enzyme activities were detected in homogenates: hexokinase, fructose-biphosphate aldolase, pyruvate kinase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, malate dehydrogenase (decarboxylating), pyruvate synthase, acetyl-CoA synthetase, alcohol dehydrogenase (NADP+), NADH dehydrogenase, NADPH dehydrogenase, NADPH oxidoreductase and superoxide dismutase. The enzymes of energy and carbohydrate metabolism are nonsedimentable (109 000 x g for 30 min). Activities of lactate dehydrogenase, hydrogenase, phosphate acetyltransferase, acetate kinase, citrate synthase, succinate dehydrogenase, fumarate hydratase and catalase were below the limits of detection. The results suggest the occurrence of glycolysis, energy production by substrate level phosphorylation and a flavin, iron-sulfur protein mediated electron transport system as well as the absence of cytochrome mediated oxidative phosphorylation and functional Krebs cycle.
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PMID:Energy metabolism of the anaerobic protozoon Giardia lamblia. 610 7

Ethanol metabolism in Acinetobacter sp. is limited by the rate of acetate assimilation in a reaction catalyzed by acetyl-CoA synthetase (EC 6.2.1.1). Effects of ions (sodium, potassium, and magnesium), byproducts of ethanol and acetaldehyde oxidation (NADH and NADPH), and pantothenic acid on this enzyme have been studied (sodium, NADH, and NADPH inhibit acetyl-CoA synthetase; pantothenic acid, potassium, and magnesium act as the enzyme activators). Conditions of culturing were developed, under which ethanol, acetaldehyde, and acetate in Acinetobacter cells were oxidized at the same rates, producing a threefold increase in the activity of acetyl-CoA synthetase in the cell-free extract. The results of studies of acetyl-CoA synthetase regulation in a mutant strain of Acinetobacter sp., which is incapable of forming exopolysaccharides, provide a basis for refining the technology of ethapolan production, involving the use of C2 substrates.
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PMID:[Regulation of acetate metabolism in a strain of Acinetobacter sp., growing on ethanol]. 1272 51

We established a novel enzyme-catalyzed poly(3-hydroxybutyrate) [P(3HB)] synthesis system capable of recycling CoA on the basis of the P(3HB) biosynthetic pathway in Ralstonia eutropha. The system includes purified beta-ketothiolase (PhaA), NADPH-dependent acetoacetyl-CoA reductase (PhaB), PHA synthase (PhaC), acetyl-CoA synthetase (Acs) and glucose dehydrogenase (GDH). In this system, acetyl-CoA was synthesized from acetate and CoA by Acs and ATP, and then two molecules of acetyl-CoA were condensed by PhaA to synthesize acetoacetyl-CoA, which was converted to (R)-3-hydroxybutyryl-CoA (3HBCoA) by PhaB and NADPH. The 3HBCoA was polymerized by PhaC and converted to P(3HB). In this system, the CoA molecules that were released during the condensation and polymerization reactions catalyzed by PhaA and PhaC, respectively, were reused successfully for the synthesis of acetyl-CoA. In addition, NADPH, which was consumed in the reduction of acetoacetyl-CoA, was regenerated by the action of GDH. In this system, the yield of P(3HB) synthesized from acetate as the substrate was 5.6 mg in a 5-ml reaction mixture, and the weight-average molecular weight and polydispersity were 6.64 x 10(6) and 1.36, respectively. Furthermore, CoA was reused at least 26 times, and NADPH was also regenerated at least 26 times during 24 h of reaction.
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PMID:Enzyme-catalyzed poly(3-hydroxybutyrate) synthesis from acetate with CoA recycling and NADPH regeneration in Vitro. 1623 16

Tub is a member of a small gene family, the tubby-like proteins (TULPs), with predominant expression in neurons. Mice carrying a mutation in Tub develop retinal and cochlear degeneration as well as late-onset obesity with insulin resistance. During behavioral and metabolic testing, we found that homozygous C57BL/6J-Tub(tub) mice have a lower respiratory quotient than C57BL/6J controls before the onset of obesity, indicating that tubby homozygotes fail to activate carbohydrate metabolism and instead rely on fat metabolism for energy needs. In concordance with this, tubby mice show higher excretion of ketone bodies and accumulation of glycogen in the liver. Quantitation of liver mRNA levels shows that, during the transition from light to dark period, tubby mice fail to induce glucose-6-phosphate dehydrogenase (G6pdh), the rate-limiting enzyme in the pentose phosphate pathway that normally supplies NADPH for de novo fatty acid synthesis and glutathione reduction. Reduced G6PDH protein levels and enzymatic activity in tubby mice lead accordingly to lower levels of NADPH and reduced glutathione (GSH), respectively. mRNA levels for the lipolytic enzymes acetyl-CoA synthetase and carnitine palmitoyltransferase are increased during the dark cycle and decreased during the light period, and several citric acid cycle genes are dysregulated in tubby mice. Examination of hypothalamic gene expression showed high levels of preproorexin mRNA leading to accumulation of orexin peptide in the lateral hypothalamus. We hypothesize that abnormal hypothalamic orexin expression leads to changes in liver carbohydrate metabolism and may contribute to the moderate obesity observed in tubby mice.
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PMID:Defective carbohydrate metabolism in mice homozygous for the tubby mutation. 1684 32

A general method for isotopic labeling of the purine base moiety of nucleotides and RNA has been developed through biochemical pathway engineering in vitro. A synthetic scheme was designed and implemented utilizing recombinant enzymes from the pentose phosphate and de novo purine synthesis pathways, with regeneration of folate, aspartate, glutamine, ATP, and NADPH cofactors, in a single-pot reaction. Syntheses proceeded quickly and efficiently in comparison to chemical methods with isolated yields up to 66% for 13C-, 15N-enriched ATP and GTP. The scheme is robust and flexible, requiring only serine, NH4+, glucose, and CO2 as stoichiometric precursors in labeled form. Using this approach, U-13C- GTP, U-13C, 15N- GTP, 13C 2,8- ATP, and U-15N- GTP were synthesized on a millimole scale, and the utility of the isotope labeling is illustrated in NMR spectra of HIV-2 transactivation region RNA containing 13C 2,8-adenosine and 15N 1,3,7,9,2-guanosine. Pathway engineering in vitro permits complex synthetic cascades to be effected, expanding the applicability of enzymatic synthesis.
ACS Chem Biol 2008 Aug 15
PMID:Pathway engineered enzymatic de novo purine nucleotide synthesis. 1870 56

Gluconeogenesis is blocked in a strain of Escherichia coli that is deficient in triosephosphate isomerase, but it was restored by the insertion of a plasmid coding for an L-glyceraldehyde 3-phosphate reductase (YghZ). This reductase provides a "bypass" that produces dihydroxyacetone phosphate (DHAP) by the consecutive enzyme-catalyzed reduction of L-glyceraldehyde 3-phosphate ( L-GAP) by NADPH to give L-glycerol 3-phosphate and reoxidation by NAD(+) catalyzed by endogenous L-glycerol 3-phosphate dehydrogenase to give DHAP. The origin of cellular L-GAP remains to be determined.
ACS Chem Biol 2008 Oct 17
PMID:Restoring a metabolic pathway. 1892 48


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