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)

Citrate synthase activity of Saccharomyces cerevisiae was determined by a radioactive assay procedure and the reaction product, 14C-citric acid, was identified by chromatographic techniques. ATP, d-ATP, GTP and NADH were most inhibitory to the citrate synthase invitro. The activity was inhibited to a lesser extent by ADP, UTP, and NADP whereas, AMP and CTP were much less inhibitory. NADH, like NAD, glutamic acid, glutamine, arginine, ornithine, proline, aspartic acid and alpha-ketoglutarate exhibited no inhibition. These results have been discussed in the light of the role of citrate synthase for the energy metabolism and glutamic acid biosynthesis.
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PMID:Regulation of citrate synthase activity of Saccharomyces cerevisiae. 0

Subcellular localization of enzymes of arginine metabolism in Saccharomyces cerevisiae was studied by partial fractionation and stepwise homogenization of spheroplast lysates. These enzymes could clearly be divided into two groups. The first group comprised the five enzymes of the acetylated compound cycle, i.e., acetylglutamate synthase, acetylglutamate kinase, acetylglutamyl-phosphate reductase, acetylornithine aminotransferase, and acetylornithine-glutamate acetyltransferase. These enzymes were exclusively particulate. Comparison with citrate synthase and cytochrome oxidase, and results from isopycnic gradient analysis, suggested that these enzymes were associated with the mitochondria. By contrast, enzymatic activities going from ornithine to arginine, i.e., arginine pathway-specific carbamoylphosphate synthetase, ornithine carbamoyltransferase, argininosuccinate synthetase, and argininosuccinate lyase, and the two first catabolic enzymes, arginase and ornithine aminotransferase, were in the "soluble" fraction of the cell.
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PMID:Arginine metabolism in Saccharomyces cerevisiae: subcellular localization of the enzymes. 20 32

Relationship of citrate synthase (EC 4.1.3.7) to the biosynthesis of glutamic acid was investigated by characterizing a new glutamic acid auxotroph FL100-D1 (glu 3) of Saccharomyces cerevisiae. Nutritional requirement of the mutant was satisfied by L-glutamic acid, L-glutamic acid peptide as well as several analogs of glutamic acid, but not by proline, ornithine, arginine, lysine or aspartic acid. The mutant was unable to utilize nonfermentable carbon sources, glycerol, acetate or lactate. Mutant glu3 unlike aconitaseless glutamic acid auxotroph glu 1, failed to accumulate 14C-citric acid in vivo from 1-14C-sodium acetate or U-14C-glutamic acid. Both spectrophotometric and radioactive assay procedures demonstrated a lack of significant citrate synthase activity in the dialysed extract of the mutant compared to the wild type strain. Mutant glu 3 complemented with glu 1 and glu 2 individually in vivo and exhibited a significant aconitase (EC 4.2.1.3) activity in vitro.
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PMID:Citrate synthaseless glutamic acid auxotroph of Saccharomyces cerevisiae. 110 43

1. The activities of enzymes of the urea cycle, carbamoyl phosphate synthetase, ornithine transcarbamoylase, argininosuccinate synthetase, argininosuccinase (the last two comprising the arginine synthetase system) and arginase, were measured in the liver during development of the rat. All five enzymes exhibited relatively low activities in foetal liver and a rapid postnatal increase was found. The rate-limiting enzyme of urea synthesis in the rat, the condensing enzyme of the arginine synthetase system, showed the lowest activity at birth and the most rapid postnatal increase, a fivefold increase within 24hr. after birth. A second increase of activity was noted after the tenth day. These results suggest that the postnatal increase of arginine synthetase activity initiates the ability for urea synthesis in the rat. 2. Some factors influencing the development of the rate-limiting arginine synthetase system were studied in more detail. (a) Intraperitoneal administration of puromycin inhibited the postnatal increaseof the enzyme activity. (b) Starvation of newborn animals for 24hr. after birth had no effect on the postnatal development of the enzyme. (c) Bilateral adrenalectomy at birth caused a marked diminution in the postnatal increase of the enzyme activity and injections of triamcinolone were effective in preventing the effect of adrenalectomy. (d) Administration of triamcinolone alone had a marked stimulatory effect on the postnatal development of this enzyme. (e) Premature and postmature birth had virtually no effect on the developmental pattern of the arginine synthetase activity, suggesting that the increase of this enzyme activity after birth is not initiated by the birth process.
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PMID:Factors influencing the development of urea-synthesizing enzymes in rat liver. 1674 4

Guanidinoacetate methyltransferase (GAMT) deficiency is a rare disorder of creatine synthesis. We report a patient who presented at 10 months of age with hypotonia and global developmental delay. Subsequently, she developed seizures and choreoathetosis. Magnetic resonance imaging showed high signal bilaterally in the globus pallidus on T2-weighted images. Mitochondrial respiratory chain studies revealed low complex I activity (in muscle 0.052 nmol NADH oxidized per min per unit citrate synthase, controls 0.166 +/- 0.047; in fibroblasts 0.080 nmol NADH oxidized per min per unit citrate synthase, controls 0.197 +/- 0.034). The true diagnosis was suspected at 21 months of age because of persistent low plasma and urine creatinine concentrations. GAMT activity was undetectable in fibroblasts and compound heterozygous mutations were found in the GAMT gene (c.327G>A and c.522G>A). The patient was treated with creatine, dietary arginine restriction and ornithine supplements. Her movement disorder and seizures resolved but she still has severe cognitive impairment and no expressive language. The occurrence of secondary respiratory chain abnormalities in GAMT deficiency may lead to misdiagnosis, particularly as the clinical and radiological features resemble those seen in mitochondrial encephalopathies. It is important to establish the correct diagnosis because specific treatment is available.
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PMID:Guanidinoacetate methyltransferase deficiency masquerading as a mitochondrial encephalopathy. 1717 76

Experimental metabolic alkalosis is known to stimulate whole-animal urea production and active ion secretion by the rectal gland in the dogfish shark. Furthermore, recent evidence indicates that a marked alkaline tide (systemic metabolic alkalosis) follows feeding in this species and that the activities of the enzymes of the ornithine-urea cycle (OUC) for urea synthesis in skeletal muscle and liver and of energy metabolism and ion transport in the rectal gland are increased at this time. We therefore evaluated whether alkalosis and/or NaCl/volume loading (which also occurs with feeding) could serve as a signal for activation of these enzymes independent of nutrient loading. Fasted dogfish were infused for 20 h with either 500 mmol L(-1) NaHCO3 (alkalosis + volume expansion) or 500 mmol L(-1) NaCl (volume expansion alone), both isosmotic to dogfish plasma, at a rate of 3 mL kg(-1) h(-1). NaHCO3 infusion progressively raised arterial pH to 8.28 (control = 7.85) and plasma [HCO3-] to 20.8 mmol L(-1) (control = 4.5 mmol L(-1)) at 20 h, with unchanged arterial P(CO2), whereas NaCl/volume loading had no effect on blood acid-base status. Rectal gland Na+,K+-ATPase activity was increased 50% by NaCl loading and more than 100% by NaHCO3 loading, indicating stimulatory effects of both volume expansion and alkalosis. Rectal gland lactate dehydrogenase activity was elevated 25% by both treatments, indicating volume expansion effects only, whereas neither treatment increased the activities of the aerobic enzymes citrate synthase, NADP-isocitrate dehydrogenase, or the ketone body-utilizing enzyme beta-hydroxybutyrate dehydrogenase in the rectal gland or liver. The activity of ornithine-citrulline transcarbamoylase in skeletal muscle was doubled by NaHCO3 infusion, but neither treatment altered the activities of other OUC-related enzymes (glutamine synthetase, carbamoylphosphate synthetase III). We conclude that both the alkaline tide and salt loading/volume expansion act as signals to activate some but not all of the elevated metabolic pathways and ionoregulatory mechanisms needed during processing of a meal.
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PMID:Is the alkaline tide a signal to activate metabolic or ionoregulatory enzymes in the dogfish shark (Squalus acanthias)? 1841 54

In insect, pyruvate is generally the predominant oxidative substrate for mitochondria. This metabolite is transported inside mitochondria via the mitochondrial pyruvate carrier (MPC), but whether and how this transporter controls mitochondrial oxidative capacities in insects is still relatively unknown. Here, we characterize the importance of pyruvate transport as a metabolic control point for mitochondrial substrate oxidation in two genotypes of an insect model, Drosophila melanogaster, differently expressing MPC1, an essential protein for the MPC function. We evaluated the kinetics of pyruvate oxidation, mitochondrial oxygen consumption, metabolic profile, activities of metabolic enzymes, and climbing abilities of wild-type (WT) flies and flies harboring a deficiency in MPC1 (MPC1^def). We hypothesized that MPC1 deficiency would cause a metabolic reprogramming that would favor the oxidation of alternative substrates. Our results show that the MPC1^def flies display significantly reduced climbing capacity, pyruvate-induced oxygen consumption, and enzymatic activities of pyruvate kinase, alanine aminotransferase, and citrate synthase. Moreover, increased proline oxidation capacity was detected in MPC1^def flies, which was associated with generally lower levels of several metabolites, and particularly those involved in amino acid catabolism such as ornithine, citrulline, and arginosuccinate. This study therefore reveals the flexibility of mitochondrial substrate oxidation allowing Drosophila to maintain cellular homeostasis.
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PMID:Metabolic Characterization and Consequences of Mitochondrial Pyruvate Carrier Deficiency in Drosophila melanogaster. 3289 62

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