Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
 2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Acetyl-CoA carboxylase was purified to homogeneity, in the presence of protein phosphatase inhibitors, from rat liver sampled without freeze-clamping. The enzyme was in a highly phosphorylated state (4.8 mol/subunit) of low specific activity, and could be dramatically reactivated by treatment with protein phosphatase-2A. Amino acid sequencing and fast-atom-bombardment mass spectrometry showed that the enzyme was phosphorylated in Ser79, Ser1200 and Ser1215, the three sites known to be phosphorylated in cell-free assays by the AMP-activated protein kinase. 2. The inactive enzyme could also be completely reactivated using a limited treatment with trypsin, which removes the N-terminal segment containing Ser79 and reduces the phosphate content to 3.5 mol/subunit. These results strengthen previous findings that it is phosphorylation at Ser79 by the AMP-activated protein kinase that is responsible for the inactivation, and not the phosphorylation of the 220-kDa core fragment (which contains Ser1200 and Ser1215). 3. Analysis of the phosphorylation state of Ser79 in acetyl-CoA carboxylase from rat liver showed that phosphorylation occurs post mortem if freeze-clamping is not used. The higher phosphorylation observed in extracts made without freeze-clamping correlates with a large increase in AMP and decrease in ATP (presumably caused by hypoxia during removal of the liver), and with increased activity of the AMP-activated protein kinase. These results provide a rational explanation for the post mortem phosphorylation events, and re-emphasize the point that rapid cooling of cells and tissues is essential when measuring the expressed activity of acetyl-CoA carboxylase (as well as 3-hydroxy-3-methylglutaryl-CoA reductase). 4. Using the freeze-clamping procedure, the ratio of 'expressed' activity (measured in the presence of protein phosphatase inhibitors) to 'total' activity (measured after complete dephosphorylation) of rat liver acetyl-CoA carboxylase showed a marked diurnal rhythm, changing from 50% in the active form in the middle of the dark period to less than 10% active in the middle of the light period. The very low activity in the light period was associated with a high level of phosphorylation in Ser79. This diurnal rhythm is very similar to that previously described for the phosphorylation of 3-hydroxy-3-methylglutaryl-CoA reductase, another substrate for the AMP-activated protein kinase. Neither the activity of the AMP-activated protein kinase nor the content of AMP, ADP or ATP changed between the dark or light periods.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Diurnal rhythm of phosphorylation of rat liver acetyl-CoA carboxylase by the AMP-activated protein kinase, demonstrated using freeze-clamping. Effects of high fat diets. 134 20

The interaction of rat liver acetyl-CoA carboxylase with a 2',3'-dialdehyde derivative of ATP (oATP) has been studied. The degree of the enzyme inactivation has been found to depend on the oATP concentration and the incubation time. ATP was proved to be the only substrate which protected the inactivation. Acetyl-CoA did not effect inactivation, while HCO3- accelerated the process. Ki values for oATP in the absence and presence of HCO3- were 0.35 +/- 0.04 and 0.5 +/- 0.06 mM, and those of the modification constant (kmod) were 0.11 and 0.26 min-1 respectively. oATP completely inhibited the [14C]ADP in equilibrium ATP exchange and did not effect the [14C]acetyl-CoA in equilibrium malonyl-CoA exchange. Incorporation of approximately 1 equivalent of [3H]oATP per acetyl-CoA carboxylase subunit has been shown. No recovery of the modified enzyme activity has been observed in Tris or beta-mercaptoethanol containing buffers, and treatment with NaB3H4 has not led to 3H incorporation. The modification elimination of the ATP triphosphate chain. The results indicated the affinity modification of acetyl-CoA carboxylase by oATP. It was shown that the reagent apparently interacted selectively with the epsilon-amino group of lysine in the ATP-binding site to form a morpholine-like structure.
 ...
PMID:Affinity labelling of rat liver acetyl-CoA carboxylase by a 2',3'-dialdehyde derivative of ATP. 196 47

The interaction between acetyl-CoA fragments and rat liver acetyl-CoA carboxylase was studied. It was found that the 3'-phosphate group did not interfere with the enzyme interaction since the substrate properties of acetyl-dephospho-CoA and acetyl-CoA are nearly identical. The non-nucleotide substrate analogs S-acetyl-pantethin and its 4'-phosphate) also displayed substrate properties (V = 1.5% and 15% of the V for acetyl-CoA carboxylation respectively). The nucleotide fragment of the acetyl-CoA molecule produced an appreciable effect on the thermodynamics of this substrate interaction with the enzyme. Its physiological role consists in all probability, in the activation and propes orientation of the acetyl group in the enzyme active center. The far more pronounced substrate properties of S-acetyl pantethin 4'-phosphate and the inhibitory properties of pantethin 4'-phosphate (compared to non-phosphorylated analogs) suggest the essential role of the beta-phosphate residue of ADP in the acetyl-CoA binding to the enzyme. The data obtained suggest also that the hydrophobic region responsible for the acyl radical binding, has a site which specifically recognizes the beta-mercaptoethyl residue of the CoA pantethin fragment. The pivotal role in the acetyl-CoA carboxylase interaction with the substrate is ascribed to the productive binding of the acetyl radical; the contribution of individual fragment of the CoA molecule is variable.
 ...
PMID:[Substrate specificity of acetyl-CoA-carboxylase from the rat liver]. 197 87

The interaction of acetyl-CoA fragments with rat liver acetyl-CoA carboxylase has been studied. Dephosphorylated acetyl-CoA did not actually differ from acetyl-CoA in its substrate properties. Non-nucleotide analogues of the substrate, S-acetylpantatheine and it's 4'-phosphate, also possess substrate properties (Vmax = 1.5% and 15% of the maximal rate value of acetyl-CoA carboxylation, respectively). The nucleotide fragment in the acetyl-CoA molecule produces a marked effect on the thermodynamics of the substrate-enzyme interaction, and is apparently involved in activation and appropriate orientation of the acetyl group in the active site. The better substrate properties of S-acetylpantetheine 4'-phosphate and the inhibitory properties of pantetheine 4'-phosphate, compared to the unphosphorylated analogues, evidence an important role of the 5'-beta-phosphate of 3'-phosphorylated ADP residue in acetyl-CoA binding to the enzyme.
 ...
PMID:Interaction of acetyl-CoA fragments with rat liver acetyl-CoA carboxylase. 197 84

The interaction of a number of ATP analogs with a modified triphosphate moiety as well as 2-chloro-ethyl-amino derivatives of nucleotides, 4(N-2-chloroethyl-N-methylamino)-benzyl-gamma-amide of ATP and the corresponding ADP beta-amide with acetyl-CoA carboxylase (EC 6.4.1.2.) from rat liver has been studied. Halophosphonate derivatives of ATP have been synthesized from bromomethylene diphosphonic acid and found to be reversible inhibitors of the enzyme. ATP and ADP alkylating amides have proved to form a reversible complex with the ATP-binding site and to modify a group in the acetyl-CoA-binding site. The bicarbonate ion accelerates the process of inactivation. The estimate of the distance between the ATP-binding site and the acetyl-CoA-binding site ranges within 0.8-1.2 nm.
 ...
PMID:Interaction of ATP with acetyl-CoA carboxylase from rat liver. The role of the polyphosphate chain. Affinity labelling with alkylating amides of ATP and ADP. 198 47

The interaction of rat liver acetyl-CoA carboxylase with a 2',3'-dialdehyde derivative of ATP (oATP) has been studied. The degree of the enzyme inactivation has been found to depend on the oATP concentration and the incubation time. ATP was the only reaction substrate which provided protection from inactivation. Acetyl-CoA did not affect inactivation, while HCO3- accelerated the process. Ki values for oATP in the absence and the presence of HCO3- were 0.35 +/- 0.04 and 0.5 +/- 0.06 mM, and those of the modification constant (k) were 0.11 and 0.26 min-1, respectively. oATP completely inhibited the reaction of [14C]ADP in equilibrium ATP exchange, whereas produced actually no effect on [14C]acetyl-CoA equilibrium with malonyl-CoA exchange. Incorporation of about one equivalent of [3H]oATP per acetyl-CoA carboxylase subunit has been shown. No restoration of the modified enzyme activity has been observed in Tris or beta-mercaptoethanol containing buffers, and treatment with NaB[3H]4 has not led to 3H incorporation. The modification process involves elimination of the triphosphate chain of oATP. The results obtained indicate the affinity character of oATP-mediated modification of acetyl-CoA carboxylase. The reagent apparently interacts selectively with the epsilon-amino group of lysine in the ATP-binding site to form a morpholine-like structure.
 ...
PMID:[Acetyl-CoA-carboxylase: modification of ATP-binding site of the active center by 2',3'-dialdehyde derivative of ATP]. 257 82

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.
 ...
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

Because of certain similarities between acetyl-CoA carboxylase (ACC) and tubulin, and the recent demonstration of the ADP-ribosylation of tubulin by cholera toxin, we have investigated a potential role for ADP-ribosylation in the regulation of ACC activity. Incubation of purified rat liver ACC with cholera toxin in the presence of millimolar concentrations of [adenylate-32P]NAD results in a time-dependent incorporation of ADP-ribose into ACC of greater than 2 mol/mol of enzyme subunit, accompanied by a marked inactivation of enzyme activity. This effect is not mimicked by pertussis toxin, ADP-ribose, or ribose 5-phosphate. Incubation of labeled ACC with snake venom phosphodiesterase and alkaline hydrolysis release 32P-products tentatively identified by high-performance liquid chromatography as 5'-[32P]AMP and [32P]ADP-ribose, respectively. These data are consistent with a mono-ADP-ribosylation of ACC catalyzed by cholera toxin. Phosphodiesterase treatment of inactivated ACC partially restores enzyme activity. The effects of ADP-ribosylation of ACC are expressed both as a decrease in the enzyme Vmax and as an increase in the apparent Ka for citrate. These results suggest that ACC might be a substrate for endogenous ADP-ribosyltransferases and that this covalent modification could be an important regulatory mechanism for the modulation of fatty acid synthesis in vivo.
 ...
PMID:Regulation of acetyl-CoA carboxylase by ADP-ribosylation. 287 58

A soluble protein that binds malonyl-CoA without requiring cofactors has been purified from rat liver. Until saturated, it competes with fatty acid synthetase for free malonyl-CoA, temporarily reducing the rate of fatty acid synthesis at low levels of malonyl-CoA, as in fatty acid synthetase--coupled assays for acetyl-CoA carboxylase. These assays yield low estimates for carboxylase activity with crude and partially purified homogenates containing the malonyl-CoA-binding protein. The protein does not inhibit assays for carboxylase activity that measure nonvolatile radioactivity incorporated from bicarbonate or NADH oxidation coupled to ADP formation. It has an Mr of 180,000 and a subunit of 90,000. It has a lower affinity for ATP, ADP, and acetyl-CoA and none for CO2 or fatty acid synthetase. No enzymatic function has been identified. The protein may regulate malonyl-CoA-binding enzymes.
 ...
PMID:A malonyl-CoA-binding protein from liver. 288 60

The interaction of 4-(N-chloroethyl-N-methylamino)-benzyl-gamma-amide ATP (I) and the corresponding beta-amide of ADP (II) with rat liver acetyl-CoA carboxylase was studied. Both analogs were shown to cause affinity modification of the enzyme. ATP and GoAS Ac protected the enzyme against inactivation. HCO3- increased the rate of carboxylase inactivation by analogs I and II (2.5- and 1.5-fold, respectively). The alkylating amides did not influence the rate of the bicarbonate-dependent [14C]-ADP-ATP exchange and inhibited the enzyme-catalyzed reaction of [14C]-CoAs Ac----CoAS Mal exchange, which testifies to the localization of the modified group in the CoAS Ac-binding site of the enzyme active center. Based on the affinity modification and analog size, it was found that the distance between the ATP- and CoAS Ac-binding sites of the enzyme active center can vary from 0.8 to 1.2 nm.
 ...
PMID:[Interaction of acetyl-CoA-carboxylase from the rat liver with alkylating amides of ATP and ADP]. 290 6


1 2 3 4 Next >>