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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)

Using stabilizing conditions the acetyl-CoA carboxylase (EC 6.4.1.2) of Pseudomonas citronellolis has been isolated as a complex containing four different polypeptide chains with molecular weights of 53 000, 36 000, 33 000 and 25 000. Evidence is presented to suggest that these polypeptide chains correspond to distinct biotin carboxylase, transcarboxylase and biotin carboxyl carrier protein subunits in analogy with similar subunits of Escherichia coli acetyl-CoA carboxylase, an unstable complex in vitro.
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PMID:Stabilization of an acetyl-coenzyme A carboxylase complex from Pseudomonas citronellolis. 1 1

The process leading to the rise of acetyl-CoA carboxylase activity in rat mammary tissue after the onset of lactation was investigated. The kinetics of change in enzyme activity and enzyme immunotitratable with antibody against avian liver acetyl-CoA carboxylase were determined during the course of lactogenic differentiation. The antibody inactivates and specifically precipitates acetyl-CoA carboxylase from rat mammary tissue as well as that from chicken liver cytosol. Characterization of the immunoprecipitate of the mammary tissue carboxylase by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis reveals a single biotin-containing polypeptide of about 230000mol.wt. This molecular weight is approximately twice that reported for the avian liver enzyme. However, chicken liver cytosol prepared in the presence of trypsin inhibitor and subjected to immunoprecipitation gives rise to a biotin-containing subunit of 230000mol.wt. as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis; omission of proteinase inhibitor leads to a subunit(s) approximately one-half this size. Throughout gestation both carboxylase activity and amounts of immunotitratable enzyme remained low; however, after parturition both parameters rose concomitantly to values 30-40 times the initial values. Therefore the elevated concentration of acetyl-CoA carboxylase appears to result from an increased rate of synthesis of enzyme relative to degradation rather than to activation of a pre-existing form of the enzyme.
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PMID:Changes in mammary-gland acetyl-coenzyme A carboxylase associated with lactogenic differentiation. 1 88

The biotin-protein populations in several bacterial strains were analyzed by solubilization of [3H]biotin-labeled cells with sodium dodecylsulfate followed by electrophoresis on polyacrylamide gels containing the detergent. A variety of patterns of biotin-labeled polypeptide chains was seen, ranging from a single biotin-protein in Escherichia coli, corresponding to the biotin carboxyl carrier protein component of acetyl-CoA carboxylase, to multiple species in Enterobacter aerogenes, Pseudomonas citronellolis, Bacillus cereus, Propionibacterium shermanii, Lactobacillus plantarum, and Mycobacterium phlei, which probably represent subunits of multiple biotin-dependent enzymes present in these organisms. In the case of Pseudomonas citronellolis two major biotin-containing polypeptides with approximate molecular weights of 65 000 and 25 000 were shown to correspond to the biotin carboxyl carrier components of pyruvate carboxylase and acetyl-CoA carboxylase, respectively. Thus in the case of Pseudomonas citronellolis two different biotin-dependent enzymes in the same cell do not share common biotin carboxyl carrier subunits.
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PMID:Analysis of bacterial biotin-proteins. 23 15

The subunit structure of rat liver acetyl-coenzyme-A carboxylase has been studied by polyacrylamide gel electrophoresis in the presence of dodecylsulfate. A number of individual preparations of the enzyme purified by the same procedures exhibited three different types of electrophoretic patterns as follows: first, a single slow-moving protein bands (Mr 230000); secondly, two adjacent fast-moving protein band (M4 124000 and 118 000); finally, all three protein bands. With the use of the [14C]biotin-labelled enzyme, the biotinyl prosthetic group was shown to be associated with the polypeptide of 230000 Mr as well as with that of 124000 Mr, but not with the polypeptide of 118000 Mr. Studies were next made with the labelled enzyme to examine the possibility that the two light polypeptides might have been formed by proteolytic modification of the heavy polypeptide during the procedures used for the purification of the enzyme. Treatment of the enzyme with trypsin or chymotrypsin resulted in cleavage of the heavy polypeptide into two nonidentical polypeptides with molecular weights of approximately 120000. Incubation of the enzyme with proteases derived from rat liver converted the heavy polypeptide into lighter polypeptides of 80000-130000 Mr. Acetyl-CoA carboxylase isolated from crude rat liver extracts by means of immunoprecipitation with specific antibody invariably showed only the heavy polypeptide. The biotin content of the enzyme was found to be 1 mol per 237000 g protein. These results indicate that rat liver acetyl-CoA carboxylase, unlike bacterial and plant biotin enzymes, has only one kind of subunit, which has a molecular weight of 230000 and contains one molecular of biotin. Thus, the mammalian enzyme exhibits a highly integrated subunit structure.
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PMID:Acetyl-coenzyme-A carboxylase from rat liver. Subunit structure and proteolytic modification. 24 Jul 17

Changes in the mass and subunit structure of liver acetyl-CoA carboxylase (ACC) accompany altered nutrition in vivo. Enzyme activity in different tissues and cell lines is also, in part, determined by variations in both total mass and ACC isoenzyme composition. ACC isoenzyme mass and hetero/homo-isoenzyme association were quantified by three sandwich e.l.i.s.a. assays, i.e. an avidin-based assay that measured total isoenzyme mass and two antibody-sandwich assays which measure polypeptide association. Results from the avidin-based assay reveal that the two major isoenzymes, of molecular mass 265 kDa (ACC 265) and 280 kDa (ACC 280), are present in markedly variable concentration in several rat and mouse tissues and in cell lines of rat and mouse origin. Hepatic ACC mass has been reported to be distributed between mitochondrial and cytosolic fractions and to undergo only a change in subcellular distribution without alteration in total mass on induction/repression of activity in vivo [Roman-Lopez, Shriver, Joseph & Alfred (1989) Biochem. J. 260, 927-930]. However, in the present study, immunoblotting and e.l.i.s.a. analysis reveals that, in rat liver, the mass of both isoenzymes is predominantly cytosolic in distribution, is markedly diminished on fasting and rises 6-8-fold on refeeding of a high-carbohydrate diet. These data support the results of several other investigations of hepatic ACC mass, and are consistent with known nutritionally altered changes in ACC mRNA content. By the two antibody-sandwich e.l.i.s.a. assays, isoenzyme complexes either composed of both ACC 280 and 265 or with multiple copies of ACC 265 are detectable in rat liver enzyme; their concentration varies independently of total ACC mass with the nutritional state of the rat, being lowest in fasting and highest on fasting/refeeding. E.l.i.s.a. analysis, applicable to crude tissue/cell extracts, provides a simple, sensitive and quantitative measurement of ACC mass and subunit composition. Its use may permit needed quantitative insight into the role of variable total ACC and isoenzyme mass and of alterations in ACC subunit composition that occur in vivo or in isolated cells in response to a variety of hormonal and nutritional influences.
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PMID:Immunological analysis of acetyl-CoA carboxylase mass, tissue distribution and subunit composition. 197 60

1. We have purified the AMP-activated protein kinase 4800-fold from rat liver. The acetyl-CoA carboxylase kinase and 3-hydroxy-3-methylglutaryl-CoA(HMG-CoA) reductase kinase activities copurify through all six purification steps and are inactivated with similar kinetics by treatment with the reactive ATP analogue fluorosulphonylbenzoyladenosine. 2. The final preparation contains several polypeptides detectable by SDS/polyacrylamide gel electrophoresis, but only one of these, with an apparent molecular mass of 63 kDa, is labelled using [14C]fluorosulphonylbenzoyladenosine. This is also the only polypeptide in the preparation that becomes significantly labelled during incubation with [gamma 32P]ATP. This autophosphorylation reaction did not affect the AMP-stimulated kinase activity. 3. In the absence of AMP the purified kinase has apparent Km values for ATP and acetyl-CoA carboxylase of 86 microM and 1.9 microM respectively. AMP increases the Vmax 3-5-fold without a significant change in the Km for either protein or ATP substrates. 4. The response to AMP depends on the ATP concentration in the assay, but at a near-physiological ATP concentration the half-maximal effect of AMP occurs at 14 microM. Studies with a range of nucleoside monophosphates and diphosphates, and AMP analogues showed that the allosteric activation by AMP was very specific. ADP gave a small stimulation at low concentrations but was inhibitory at high concentrations. 5. These results show that the AMP-activated protein kinase is the major HMG-CoA reductase kinase detectable in rat liver under our assay conditions and that it is therefore likely to be identical to previously described HMG-CoA reductase kinase(s) which are activated by adenine nucleotides and phosphorylation. The AMP-binding and catalytic domains of the kinase are located on a 63-kDa polypeptide which is subject to autophosphorylation.
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PMID:Purification and characterization of the AMP-activated protein kinase. Copurification of acetyl-CoA carboxylase kinase and 3-hydroxy-3-methylglutaryl-CoA reductase kinase activities. 259 24

Proteolysis of acetyl-CoA carboxylase was examined with cathepsin B. When chicken liver acetyl-CoA carboxylase was incubated with cathepsin B at pH 6.3, the native 220-kDa polypeptide was primarily cleaved into two polypeptides of 125 and 115 kDa, and further degraded to polypeptides of 100-50 kDa.
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PMID:Proteolysis of liver acetyl coenzyme A carboxylase by cathepsin B. 285 34

Limited proteolysis of chicken liver acetyl-CoA carboxylase by staphylococcal serine proteinase yielded a fragment of 31 kDa which contained the biotinyl active site. This polypeptide was purified by preparative polyacrylamide gel electrophoresis and characterized. The complete amino acid sequence of this polypeptide has been deduced from the nucleotide sequence of cloned DNA complementary to the chicken liver acetyl-CoA carboxylase mRNA. A highly conserved sequence of Met-Lys-Met was found in the biotin-binding site. Appreciable homology was observed among the sequences in close vicinity of the biotin sites of chicken liver acetyl-CoA carboxylase and other biotin-dependent carboxylases including biotin carboxyl carrier protein of Escherichia coli acetyl-CoA carboxylase.
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PMID:Primary structure of the biotin-binding site of chicken liver acetyl-CoA carboxylase. 287 45

The complete amino acid sequence of acetyl-CoA carboxylase from chicken liver has been deduced by cloning and sequence analysis of DNA complementary to its messenger RNA. The results were confirmed by Edman degradation of peptide fragments obtained by digestion of the enzyme polypeptide with Achromobacter proteinase I or staphylococcal serine proteinase. Chicken liver acetyl-CoA carboxylase is predicted to be composed of 2,324 amino acid residues, having a calculated molecular weight of 262,706. The biotin carboxyl carrier protein domain is located in the middle region of the enzyme polypeptide. The amino-terminal portion of the acetyl-CoA carboxylase has been found to exhibit a homologous primary structure to that of carbamyl phosphate synthetase. Localization of possible functional domains including biotin carboxylase subsite in the acetyl-CoA carboxylase polypeptide is discussed.
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PMID:Primary structure of chicken liver acetyl-CoA carboxylase deduced from cDNA sequence. 289 93

Acetyl-coenzyme A carboxylase (Ac-CoA carboxylase; EC 6.4.1.2) catalyzes the rate-limiting reaction in long-chain fatty acid biosynthesis. To investigate the mechanism of genetic control of expression of Ac-CoA carboxylase and the relationship between its structure and function, cDNA clones for Ac-CoA carboxylase were isolated. The complete coding sequence contains 7035 bases; it encodes a polypeptide chain of 2345 amino acids having a Mr of 265,220. The sequences of several CNBr peptides of Ac-CoA carboxylase were localized within the predicted protein sequence as were those peptides that contain the sites for phosphorylation. The deduced protein contains one putative site for biotinylation in the NH2-terminal half. The "conserved" biotinylation site peptide, Met-Lys-Met, is preceded by valine, whereas alanine is found in a similar position in all other known biotin-containing proteins. The primary sequences of Ac-CoA carboxylase and carbamoyl phosphate synthetase exhibit substantial identity.
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PMID:Structure of the coding sequence and primary amino acid sequence of acetyl-coenzyme A carboxylase. 290 Oct 88


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