Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biotinyl proteins were labelled by incubation of SDS-denatured preparations of subcellular fractions of rat liver with [14C]methylavidin before polyacrylamide-gel electrophoresis. Fluorographic analysis showed that mitochondria contained two forms of acetyl-CoA carboxylase [acetyl-CoA:carbon dioxide ligase (ADP-forming) EC 6.4.1.2], both of which were precipitated by antibody to the enzyme. When both forms were considered, almost three-quarters of the total liver acetyl-CoA carboxylase was found in the mitochondrial fraction of liver from fed rats while only 3.5% was associated with the microsomal fraction. The remainder was present in cytosol, either as the intact active enzyme or as a degradation product. The actual specific activity of the cytosolic enzyme was approx. 2 units/mg of acetyl-CoA carboxylase protein while that of the mitochondrial enzyme was about 20-fold lower, indicating that mitochondrial acetyl-CoA carboxylase was relatively inactive. Fractionation of mitochondria with digitonin showed that acetyl-CoA carboxylase was associated with the outer mitochondrial membrane. The available evidence suggests that mitochondrial acetyl-CoA carboxylase represents a reservoir of enzyme which can be released and activated under lipogenic conditions.
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PMID:Enzymatically inactive forms of acetyl-CoA carboxylase in rat liver mitochondria. 290 Dec 59

1. The effects of 2-oxo-4-methylpentanoate, 2-oxo-3-methylbutanoate and 2-oxo-3-methylpentanoate on the activity of pyruvate dehydrogenase (EC 1.2.4.1), citrate synthase (EC 4.1.3.7), acetyl-CoA carboxylase, (EC 6.4.1.2) and fatty acid synthetase derived from the brains of 14-day-old rats were investigated. 2. The pyruvate dehydrogenase enzyme activity was competitively inhibited by 2-oxo-3-methylbutanoate with respect to pyruvate with a K(i) of 2.04mm but was unaffected by 2-oxo-4-methylpentanoate or 2-oxo-3-methylpentanoate. 3. The citrate synthase activity was inhibited competitively (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (K(i)~7.2mm) and 2-oxo-3-methylbutanoate (K(i)~14.9mm) but not by 2-oxo-3-methylpentanoate. 4. The acetyl-CoA carboxylase activity was not inhibited significantly by any of the 2-oxo acids investigated. 5. The fatty acid synthetase activity was competitively inhibited (with respect to acetyl-CoA) by 2-oxo-4-methylpentanoate (K(i)~930mum) and 2-oxo-3-methylpentanoate (K(i)~3.45mm) but not by 2-oxo-3-methylbutanoate. 6. Preliminary experiments indicate that 2-oxo-4-methylpentanoate and 2-oxo-3-phenylpropionate (phenylpyruvate) significantly inhibit the ability of intact brain mitochondria from 14-day-old rats to oxidize pyruvate. 7. The results are discussed with reference to phenylketonuria and maple-syrup-urine disease. A biochemical mechanism is proposed to explain the characteristics of these diseases.
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PMID:Differential effects of 2-oxo acids on pyruvate utilization and fatty acid synthesis in rat brain. 415 48

The total cytosol activity of acetyl-CoA carboxylase (acetyl-CoA:CO(2) ligase (ADP), EC 6.4.1.2) in the liver is known to be 6- to 10-fold higher in genetically obese hyperglycemic mice (C57BL/6J-ob) than in nonobese mice. The results of immunochemical titrations, Ouchterlony double-diffusion analysis, and kinetic and heat inactivation studies indicated that this rise in the level of carboxylase activity in liver extracts from obese mice was ascribed to an increase in the quantity of the enzyme protein, which was indistinguishable from that derived from nonobese mice. Combined immunochemical and isotopic techniques showed that the rate of synthesis of the carboxylase per liver was 7.7-fold higher in obese than in nonobese mice. The rate of degradation of the carboxylase was found to be 1.7-fold lower in obese than in nonobese mice, the half-life being 115 and 67 hr, respectively. These results indicate that the increase in the acetyl-CoA carboxylase content of the liver in obese mice is due mainly to a rise in the rate of enzyme synthesis, and in a minor degree, to a decrease in the rate of enzyme degradation.
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PMID:Synthesis and degradation of liver acetyl coenzyme A carboxylase in genetically obese mice. 500 32

1. Although citrate is known to activate purified preparations of acetyl-CoA carboxylase, it had no stimulatory effect on the incorporation of [(14)C]acetate into long-chain fatty acids in a whole homogenate of rat liver (S(0.7)) under conditions in which the activity of acetyl-CoA carboxylase was rate-limiting for fatty acid synthesis. 2. The rate of incorporation of acetyl carbon into fatty acids was estimated in S(0.7) preparations incubated with [(14)C]acetate, by measuring the specific radioactivity of the acetyl carbon of acetyl-CoA and the incorporation of (14)C into fatty acids. These estimates were compared with estimates of acetyl-CoA carboxylase activity in the S(0.7) preparation obtained by direct assay in conditions in which the enzyme was in the fully activated state. 3. In the absence of citrate, incorporation of acetyl carbon into fatty acids was about 75% of the value expected if the acetyl-CoA carboxylase in the S(0.7) preparation were in the fully activated state. 4. Incorporation of acetyl carbon into fatty acids in the S(0.7) preparation was stimulated by citrate, but the effect was many times less than the stimulation of [(14)C]acetate incorporation by citrate in particle-free preparations. 5. When the mitochondria and microsomes were removed from the S(0.7) preparation, [(14)C]acetate incorporation into fatty acids fell to a negligible value and the preparation became highly sensitive to stimulation by citrate. 6. It is suggested that in the presence of mitochondria and microsomes, and in the intact liver cell, the degree of activation of acetyl-CoA carboxylase is such that citrate activation may not be of physiological significance.
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PMID:The sensitivity of acetyl-coenzyme A carboxylase to citrate stimulation in a homogenate of rat liver containing subcellular particles. 542 55

1. Methods are described for the extraction and assay of acetyl-CoA and of total acid-soluble and total acid-insoluble CoA derivatives in rat epididymal adipose tissue. 2. The concentration ranges of the CoA derivatives in fat pads incubated in vitro under various conditions were: total acid-soluble CoA, 0.20-0.59mm; total acid-insoluble CoA, 0.08-0.23mm; acetyl-CoA, 0.03-0.14mm. 3. An investigation was made of some postulated mechanisms of control of fatty acid and triglyceride synthesis in rat epididymal fat pads incubated in vitro. The concentrations of intermediates of possible regulatory significance were measured at various rates of fatty acid and triglyceride synthesis produced by the addition to the incubation medium (Krebs bicarbonate buffer containing glucose) of insulin, adrenaline, albumin, palmitate or acetate. 4. The whole-tissue concentrations of glucose 6-phosphate, l-glycerol 3-phosphate, citrate, acetyl-CoA, total acid-soluble CoA and total acid-insoluble CoA were assayed after 30 or 60min. incubation. The rates of fatty acid and triglyceride synthesis, calculated from the incorporation of [U-(14)C]glucose into fatty acids and glyceride glycerol respectively, and the rates of glucose uptake, lactate plus pyruvate output and glycerol output were measured over a 60min. incubation. 5. The rate of triglyceride synthesis could not be correlated with the concentrations of either l-glycerol 3-phosphate or long-chain fatty acyl-CoA (measured as total acid-insoluble CoA). Factor(s) other than the whole-tissue concentrations of these recognized precursors appear to be involved in the determination of the rate of triglyceride synthesis. 6. No relationship was found between the rate of fatty acid synthesis and the whole-tissue concentrations of the intermediates, citrate or acetyl-CoA, or with the two proposed effectors of acetyl-CoA carboxylase, citrate (as activator) or long-chain fatty acyl-CoA (as inhibitor). The control of fatty acid synthesis appears to reside in additional or alternative factors.
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PMID:The control of fatty acid and triglyceride synthesis in rat epididymal adipose tissue. Roles of coenzyme A derivatives, citrate and L-glycerol 3-phosphate. 574 24

Acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] is activated by physiological concentrations of CoA. The CoA concentration dependency of this activation is sigmoidal; below 60 microM there is little or no activation, but the activation observed between 60 and 120 microM indicates that small changes in the concentration of CoA can cause significant changes in carboxylase activity. CoA activation of acetyl-CoA crboxylase accompanies polymerization of acetyl-CoA carboxylase. However, the binding site for CoA appears to be different from that of citrate. In contrast to citrate activation, which changes only the Vmax of the reaction, CoA activation of carboxylase results in polymeric forms with a lower Km for acetyl-CoA. The Km for acetyl-CoA is 0.4 mM in the control enzyme, whereas that of the CoA-activated enzyme is as low as 4 microM. The Km for ATP was not changed. Derivatives of CoA were not effective in activating the carboxylase, indicating that the CoA effect is specific. Arguments are presented that CoA could be a physiologically significant positive effector of the carboxylase.
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PMID:Regulation of acetyl-coA carboxylase: properties of coA activation of acetyl-coA carboxylase. 610 89

Among more than 7000 mutants of Saccharomyces cerevisiae, requiring saturated fatty acids, 61 acetyl-CoA-carboxylase-deficient strains have been identified. According to their mutual complementation characteristics these mutants have been assigned to two different genes, acc1 and acc2. Both acetyl-CoA carboxylase genes are unlinked to each other and to the fatty acids synthetase genes fas1 and fas2. The acetyl-CoA carboxylases of several acc1 and acc2 mutants have been purified and assayed for their overall and component enzyme activities. Besides overall acetyl-CoA carboxylation, which was lost in all cases, both component enzymes, biotin carboxylase and transcarboxylase, were simultaneously affected in most mutants, though often to a different relative extent. Similarly, the comparison of biochemical and genetic complementation data revealed no basis for a clear distinction between specific biotin carboxylase and transcarboxylase mutants. These results suggest that acc1 is a cluster gene coding for a multifunctional protein harboring both acetyl-CoA carboxylase component enzyme activities on the same polypeptide chain. The acetyl-CoA carboxylase isolated from acc2 mutants was free of biotin. Correspondingly, biotin:apoacetyl-CoA-carboxylase ligase activity was missing in acc2 mutants. Therefore, it is concluced that the primary defect in acc2 mutants is in the biotin:apocarboxylase ligase. In agreement with this conclusion, the acc2 acetyl-CoA carboxylase can be activated, in the presence of biotin and ATP, by ligase preparations from wild-type or acc1 mutant cells. By the use of these mutants, evidence was obtained that in vivo the biotinylation of both acetyl-CoA carboxylase and pyruvate carboxylase is catalyzed by the same ligase.
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PMID:Yeast mutants defective in acetyl-coenzyme A carboxylase and biotin: apocarboxylase ligase. 610 18

Acetyl-CoA carboxylase is activated by physiological concentrations of CoA. Activation of partially purified enzyme by CoA is accompanied by a decrease in the Km for acetyl-CoA from 0.2 mM to about 4 microM, which is the physiological concentration of acetyl-CoA in the cytosol. CoA activation of the purified enzyme is accompanied by an increase in the Vmax, without changing the Km for acetyl-CoA. The Km for acetyl-CoA of the purified enzyme is about 10 to 40 microM. The purification procedure results in a decrease in the Km for acetyl-CoA; under these conditions, CoA activation does not cause further lowering of the Km. CoA activation is accompanied by polymerization of the enzyme. However, CoA activation is not causally related to polymerization. There is one CoA binding site/subunit of acetyl-CoA carboxylase. CoA binding at that site is not affected by the presence of citrate, but palmityl-CoA inhibits CoA binding. CoA alone cannot reverse palmityl-CoA inhibition of the carboxylase. Bovine serum albumin and CoA together can activate the palmityl-CoA-inhibited enzyme. This indicates that the involvement of bovine serum albumin-like protein, CoA, and palmityl-CoA may play a physiologically significant role in the control of acetyl-CoA carboxylase.
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PMID:Coenzyme A activation of acetyl-CoA carboxylase. 610 27

Changes of acetyl-CoA-carboxylase (EC 6.4.1.2) activity and the NAD content in the liver tissue were studied in dynamics after excessive administration of nicotinic acid to chickens. It is established that in chickens, which were given a high-carbohydrate diet after fasting, administration of nicotinic acid at first causes a fall of the acetyl-CoA-activity in the liver tissue, followed by its gradual rise against a background of the NAD content drop and by the 24th hour its level approaches the initial values. The maxima of NAD accumulation and of the acetyl-CoA-carboxylase activity decrease coincide in time. The administration of nicotinic acid to these chickens causes both a decrease in the intensity of 2-14C acetate incorporation into free fatty acids and a drop in their content.
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PMID:[Nicotinic acid effect on acetyl-CoA-carboxylic activity in chicken liver]. 611 Nov 43

The activity of 3-hydrosy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and the rate of mevalonic acid (MVA) synthesis from [I-14C]acetyl-CoA and [2-14C]malonyl-CoA in the soluble (X140000 g) and microsomal fractions of rat liver and in a reconstituted system containing the soluble and microsomal fractions were studied. The changes in the activity of HMG-CoA reductase and the rate of MVA biosynthesis in the fractions at different times of the day were analyzed. The daily rhythms of the rate of acetyl-CoA and malonyl-CoA incorporation into squalene, sterols and fatty acids in the postmitochondrial fraction and the daily changes in the acetyl-CoA carboxylase activity of the soluble fraction of rat liver were compared. The incorporation of labelled acetyl-CoA and malonyl-CoA into MVA showed that the latter can be synthesized from these two substrates both in the soluble and microsomal fractions. Malonyl-CoA is a preferable substrate for MVA synthesis in the soluble fraction. MVA synthesis from acetyl-CoA proceeds fastr in the intact and solubilized microsomes than in the soluble fraction. The activity of HMG-CoA reductase was found in the soluble and microsomal fractions in practically equal amounts. The enzyme activity was increased in the microsomal fraction after its solubilization. The rate of MVA biosynthesis from acetyl-CoA and the activity of HMG-CoA reductase in the soluble fraction are practically unaffected by day-to-night changes. The activity of HMG-CoA reductase and MVA biosynthesis from acetyl-CoA in the intact and solubilized microsomal fractions reached their maximal values in the middle of the dark period. The rate of MVA biosynthesis from malonyl-CoA was decreased in the middle of the dark period in all fractions studied and reached its maximum in the middle of the light period. The daily rhythms of the acetyl-CoA carboxylase activity in the soluble fraction and the rate of MVA biosynthesis from malonyl-CoA in all fractions show a coincidence. a comparison of incorporation by the postmitochondrial fractions of acetyl-CoA and malonyl-CoA into the total non-saponified lipid fraction and its components, e. g. squalene, lanosterol and cholesterol, as well as into sterols precipitated by digitonin, showed that malonyl-CoA incorporation into the total non-saponified lipid fraction was more intensive than that of acetyl-CoA. However, acetyl-CoA was far more efficiently incorporated into sterols precipitated by digitonin or isolated by TLC than malonyl-CoA. The rate of acetyl-CoA incorporation into the total non-saponified lipid fraction and into squalene, lanosterol and cholesterol was maximal in the middle of the dark period and minimal in the middle of the light period. On the contrary, the rate of malonyl-CoA incorporation into these products was minimal in the middle of the dark period and maximal in the middle of the light period. The rate of fatty acid biosynthesis from acetyl-CoA was increased in the middle of the light and dark periods...
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PMID:[Activities of 3-hydroxy-3-methylglutaryl-CoA reductase and acetyl-CoA carboxylase and rate of biosynthesis of mevalonic acid, squalene, sterols and fatty acids from [1-14C]acetyl-CoA and [2-14C]malonyl-CoA in rat liver: changes induced by daily rhythm]. 611 51


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