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:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Deca-2,4,6,8-tetraenoic acid is a substrate for both ATP-specific (EC 6.2.1.2 or 3) and GTP-specific (EC 6.2.1.-) acyl-CoA synthetases of rat liver mitochondria. The enzymic synthesis of decatetraenoyl-CoA results in new spectral characteristics. The difference spectrum for the acyl-CoA minus free acid has a maximum at 376nm with epsilon(mM) 34. Isosbestic points are at 345nm and 440nm. 2. The acylation of CoA by decatetraenoate in mitochondrial suspensions can be continuously measured with a dual-wavelength spectrophotometer. 3. By using this technique, three distinct types of acyl-CoA synthetase activity were demonstrated in rat liver mitochondria. One of these utilized added CoA and ATP, required added Mg(2+) and corresponded to a previously described ;external' acyl-CoA synthetase. The other two acyl-CoA synthetase activities utilized intramitochondrial CoA and did not require added Mg(2+). Of these two ;internal' acyl-CoA synthetases, one was insensitive to uncoupling agents, was inhibited by phosphate or arsenate, and corresponded to the GTP-specific enzyme. The other corresponded to the ATP-specific enzyme. 4. Atractylate inhibited the activity of the two internal acyl-CoA synthetases only when the energy source was added ATP. 5. The amount of intramitochondrial CoA acylated by decatetraenoate was independent of whether the internal ATP-specific or GTP-specific acyl-CoA synthetase was active. It is concluded that these two internal acyl-CoA synthetases have access to the same intramitochondrial pool of CoA. 6. The amount of intramitochondrial CoA that could be acylated with decatetraenoate was decreased by the addition of palmitoyl-dl-carnitine, 2-oxoglutarate, or pyruvate. These observations indicated that pyruvate dehydrogenase (EC 1.2.4.1), oxoglutarate dehydrogenase (EC 1.2.4.2), carnitine palmitoyltransferase (EC 2.3.1.-), citrate synthase (EC 4.1.3.7), and succinyl-CoA synthetase (EC 6.2.1.4) all have access to the same intramitochondrial pool of CoA as do the two internal acyl-CoA synthetases.
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PMID:Spectrophotometric studies of acyl-coenzyme A synthetases of rat liver mitochondria. 550 Mar 16

1. CoA, acetyl-CoA, l-carnitine and acetyl-l-carnitine when added to rat liver mitochondria equilibrate with approximately two-thirds of the total intramitochondrial water. The mitochondrial space calculated to be freely permeable to these solutes was identical with that obtained for sucrose. 2. Acetyl-CoA is rapidly deacylated by rat liver mitochondria at 0 degrees C, and special precautions are required to measure its mitochondrial permeation. 3. Rat liver mitochondria were separated into fractions that correspond to the inner membrane, the outer membrane, and the soluble proteins of the matrix and intermembrane compartment. Soluble enzymes considered to be located in the matrix were citrate synthase (EC 4.1.3.7), palmitoyl-CoA dehydrogenase (EC 1.3.2.2), electron-transferring flavoprotein, medium-chain-length ATP-specific fatty acyl-CoA synthetase (EC 6.2.1.2), l-3-hydroxybutyryl-CoA dehydrogenase (EC 1.1.1.35) and 3-keto-acyl-CoA thiolase (EC 2.3.1.16). Carnitine palmitoyltransferase (EC 2.3.1.-) is largely associated with the inner-membrane fraction. A long-chain-length ATP-specific fatty acyl-CoA synthetase (EC 6.2.1.3) is associated with the outer-membrane fraction.
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PMID:The localization of some coenzyme A-dependent enzymes in rat liver mitochondria. 550 Mar 17

The activities of the eight citric acid-cycle enzymes of rat bone-marrow cells were determined along with several other mitochondrial and non-mitochondrial enzymes. Four of the citric acid-cycle enzymes (aconitase, succinyl-CoA thiokinase, alpha-oxoglutarate dehydrogenase and succinate dehydrogenase) have closely similar low activities; two [isocitrate dehydrogenase (NAD) and citrate synthase] have intermediate activities; the remaining two (malate dehydrogenase and fumarase) have high activities. The other enzymes surveyed also exhibited a spread of three orders of magnitude, the mitochondrial enzymes showing no less variation than the others.
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PMID:The activities of the citric acid-cycle enzymes in rat bone-marrow cells. 566 55

The Arabidopsis FATTY ACID ELONGATION1 (FAE1) gene encodes a putative seed-specific condensing enzyme. It is the first of four enzyme activities that comprise the microsomal fatty acid elongase (FAE) involved in the biosynthesis of very-long-chain fatty acids (VLCFAs). FAE1 has been expressed in yeast and in tissues of Arabidopsis and tobacco, where significant quantities of VLCFAs are not found. The introduction of FAE1 alone in these systems is sufficient for the production of VLCFAs, for wherever FAE1 was expressed, VLCFAs accumulated. These results indicate that FAE1 is the rate-limiting enzyme for VLCFA biosynthesis in Arabidopsis seed, because introduction of extra copies of FAE1 resulted in higher levels of the VLCFAs. Furthermore, the condensing enzyme is the activity of the elongase that determines the acyl chain length of the VLCFAs produced. In contrast, it appears that the other three enzyme activities of the elongase are found ubiquitously throughout the plant, are not rate-limiting and play no role in the control of VLCFA synthesis. The ability of yeast containing FAE1 to synthesize VLCFAs suggests that the expression and the acyl chain length specificity of the condensing enzyme, along with the apparent broad specificities of the other three FAE activities, may be a universal eukaryotic mechanism for regulating the amounts and acyl chain length of VLCFAs synthesized.
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PMID:Very-long-chain fatty acid biosynthesis is controlled through the expression and specificity of the condensing enzyme. 926 55

Diabetic states are characterized by a raised serum/islet level of triglycerides and a lowered EC50 (concentration at half-maximal stimulation) for glucose-induced insulin secretion. Culturing islets with long-chain fatty acids (FAs) replicates the basal insulin hypersecretion. In a previous study, we showed that the mechanism involved deinhibition of hexokinase by a 60% decrease in glucose-6-phosphate (G-6-P). The key event was proposed to be an increased phosphofructokinase (PFK) Vmax secondary to an upregulatory effect of the FA metabolite, long-chain acyl-coenzyme A (LC-CoA). We now show another contributory factor, a lowered content of the PFK inhibitor citrate. Citrate synthase Vmax and citrate levels were lowered 45% in rat islets cultured with 250 micromol/l oleate for 24 h. Both effects were reversed by triacsin C, an inhibitor of fatty acyl-CoA synthetase, the enzyme that generates LC-CoA. Culturing islets with high doses of glucose (16.7 mmol/l) for 48 h should also raise cytosolic LC-CoA. As predicted, citrate synthase Vmax was lowered and PFK Vmax was increased, both in a triacsin C-reversible fashion. These results show shared selected functional and biochemical properties in beta-cells of so-called glucotoxicity and lipotoxicity.
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PMID:Shared biochemical properties of glucotoxicity and lipotoxicity in islets decrease citrate synthase activity and increase phosphofructokinase activity. 983 20

A Caenorhabditis elegans ORF encoding the presumptive condensing enzyme activity of a fatty acid elongase has been characterized functionally by heterologous expression in yeast. This ORF (F56H11. 4) shows low similarity to Saccharomyces cerevisiae genes involved in fatty acid elongation. The substrate specificity of the C. elegans enzyme indicated a preference for Delta(6)-desaturated C18 polyunsaturated fatty acids. Coexpression of this activity with fatty acid desaturases required for the synthesis of C20 polyunsaturated fatty acids resulted in the accumulation of arachidonic acid from linoleic acid and eicosapentaenoic acid from alpha-linolenic acid. These results demonstrate the reconstitution of the n-3 and n-6 polyunsaturated fatty acid biosynthetic pathways. The C. elegans ORF is likely to interact with endogenous components of a yeast elongation system, with the heterologous nematode condensing enzyme F56H11.4 causing a redirection of enzymatic activity toward polyunsaturated C18 fatty acid substrates.
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PMID:Heterologous reconstitution in yeast of the polyunsaturated fatty acid biosynthetic pathway. 1082 69

The fatty acid elongase-1 beta-ketoacyl-CoA synthase, FAE1 KCS, a seed-specific elongase condensing enzyme from Arabidopsis, is involved in the production of eicosenoic (C20:1) and erucic (C22:1) acids. Alignment of the amino acid sequences of FAE1 KCS, KCS1, and five other putative elongase condensing enzymes (KCSs) revealed the presence of six conserved cysteine and four conserved histidine residues. Each of the conserved cysteine and histidine residues was individually converted by site-directed mutagenesis to both alanine and serine, and alanine and lysine respectively. After expression in yeast cells, the mutant enzymes were analyzed for their fatty acid elongase activity. Our results indicated that only cysteine 223 is an essential residue for enzyme activity, presumably for acyl chain transfer. All histidine substitutions resulted in complete loss of elongase activity. The loss of activity of these mutants was not due to their lower expression level since immunoblot analysis confirmed each was expressed to the same extent as the wild type FAE1 KCS.
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PMID:Active-site residues of a plant membrane-bound fatty acid elongase beta-ketoacyl-CoA synthase, FAE1 KCS. 1134 60

Plant fatty acid elongase which catalyzes very-long-chain fatty acid (VLCFA) biosynthesis is a membrane-bound multienzyme complex. It is composed of four enzymes, a 3-ketoacyl-CoA synthase (condensing enzyme), a 3-ketoacyl-CoA reductase, a 3-hydroxyacyl-CoA dehydrase, and an enoyl-CoA reductase required for completion of each step of 2-carbon elongation of fatty acids. To improve our understanding of the overall regulation of the fatty acid elongase, we investigated the spatial and temporal expression of its key component, the FAE1-condensing enzyme, and examined the activity of the promoter of the FAE1 gene in Arabidopsis. In situ hybridization results revealed that FAE1 transcripts were found exclusively in the embryo. RNA blot analysis and histochemical analysis of GUS activity in pFAE1::GUS transgenic Arabidopsis lines demonstrated that the FAE1 gene was already transcribed in the early torpedo stage embryos 4-5 days after flowering, with transcription reaching its peak 9-11 days after flowering. VLCFA deposition closely paralleled FAE1 transcript accumulation. FAE1 promoter was highly active and embryo-specific. Because its timing coincides with the period of major storage lipid accumulation, and because its in vivo activity in Arabidopsis is superior to the napin promoter, FAE1 promoter may be ideal for genetic engineering of seed oil composition.
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PMID:Expression of the FAE1 gene and FAE1 promoter activity in developing seeds of Arabidopsis thaliana. 1157 26

The purpose of this study was to determine if there were differences in the capacity of skeletal muscle from morbidly obese Black and White American women to oxidize fatty acids. The oxidation rates of (14)C-palmitate, (14)C-palmitoyl-CoA, and (14)C-palmitoyl-carnitine were measured in whole homogenates of rectus abdominus from Black and White women who were similar in age and body mass index (BMI). The activities of muscle citrate synthase (CS), beta-hydroxy acyl-CoA dehydrogenase (beta-HAD), and mitochondrial and microsomal acyl-CoA synthetase (ACS) were measured in the 2 groups. The results showed that the rate of (14)C-palmitate oxidation by muscle of Black women was 25% that of Whites (8.7 +/- 1.5 v 34.4 +/- 6.8 nmol (14)CO(2) produced/gram tissue wet weight/ hour; P <.05), but the rates of (14)C-palmitoyl-CoA and (14)C-palmitoyl-carnitine oxidation were not different in the 2 groups. No differences were found in the activities of CS or beta-HAD. However, the activities of both mitochondrial and microsomal ACS were lower in the Black women than the Whites (mitochondrial ACS 25.1 +/- 3.9 v 36.4 +/- 5.0 nmol/mg protein/min; P <.05; microsomal ACS 6.2 +/- 0.5 v 8.5 +/- 0.5; nmol/mg protein/min; P <.005). The lower rate of palmitate oxidation, and the lack of differences in the rates of palmitoyl-CoA and palmitoyl-carnitine oxidation indicate that there is a defect in the activation of the fatty acid in the muscle of the Black women. This was confirmed by the decrease in mitochondrial ACS activity in the Black women. The decreased fatty acid oxidation by skeletal muscle of obese Black women could result in shunting these fuels from muscle to adipose tissue for storage, which may contribute to the maintenance of obesity in the Black women.
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PMID:Fatty acid oxidation by skeletal muscle homogenates from morbidly obese black and white American women. 1280 Jan

In this study, the phosphoproteome of Corynebacterium glutamicum, an industrially important soil bacterium of the Corynebacterium/Mycobacterium/Nocardia (CMN) group of Gram-positive bacteria, was investigated by two different detection methods: first, by in vivo radio-labeling using [(33)P]-phosphoric acid with subsequent autoradiography and second, by immunostaining with phosphoamino acid-specific monoclonal antibodies. After two-dimensional gel electrophoresis (2-DE), around 60 [(33)P]-labeled protein spots were visualized and around 90 antibody-decorated protein spots detected; 31 of the protein spots were detected with both methods. By peptide mass fingerprinting, 41 different proteins were identified, namely 5-enolpyruvylshikimate 3-phosphate synthase, aconitase, acyl-CoA carboxylase, acyl-CoA synthetase, ATP (synthase alpha- and beta-chain), carbamoyl-phosphate synthase, citrate synthase, cysteine synthase, DnaK, the elongation factors G, P, Ts and Tu, enolase, fructose bisphosphate aldolase, fumarase, Gap dehydrogenase, glutamine synthetase I, glycine hydroxymethyltransferase, GroEL2, GTPase, heat-inducible transcriptional repressor DnaJ2, inorganic pyrophosphatase, isocitrate dehydrogenase, ketol-acid reductoisomerase, lactate dehydrogenase, leucine-tRNA ligase, lipoamide dehydrogenase, methionine synthase, O-acetylhomoserine sulfhydrylase, pyruvate carboxylase, pyruvate kinase, pyruvate oxidase, ribosomal protein S1, RNA polymerase (beta-subunit), succinyl-CoA:CoA transferase, transketolase and UDP-N-acetylmuramoyl-L-alanine ligase, besides a hypothetical 35k protein and a hypothetical glucose kinase. Both detection techniques were used to create a phosphoproteome map. Additionally, the influence of nitrogen deprivation on the phosphoproteome of C. glutamicum was investigated.
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PMID:Towards a phosphoproteome map of Corynebacterium glutamicum. 1292 88


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