scholarly journals Citrate Synthetase in Mitochondria and Glyoxysomes of Maize Scutellum

1974 ◽  
Vol 53 (6) ◽  
pp. 802-807 ◽  
Author(s):  
Daniela Barbareschi ◽  
Giovanna P. Longo ◽  
Orietta Servettaz ◽  
Tullio Zulian ◽  
Claudio P. Longo
Keyword(s):  
Citrate Synthetase

Effect of Phenylalanine and Its Metabolites on the Metabolism of Leucocytes and Lymphocytes

1975 ◽  
Vol 49 (4) ◽  
pp. 343-351
Author(s):  
D. M. Bradley ◽  
R. F. Mahler
Keyword(s):  
Leucine Incorporation ◽  
Published Data ◽  
Suitable Model ◽  
Acetate Incorporation ◽  
Inborn Errors ◽  
Insoluble Material ◽  
Model Cell ◽  
Resting Lymphocytes ◽  
Citrate Synthetase

1. The pathogenesis of the mental retardation in phenylketonuria remains obscure. Leucocytes have proved of value in the study of other inborn errors of metabolism. The lymphocyte is a suitable model cell for the study of mammalian metabolism, because of its ability to divide in vitro in response to various stimuli. 2. We have examined the effects of phenylalanine, phenylpyruvate, phenyl-lactate and phenylacetate on the human leucocyte and the resting and phyto-haemagglutinin-stimulated rabbit lymphocyte. 3. Phenylpyruvate and phenyl-lactate reduced acetate incorporation into leucocyte lipid by 38% and 48% respectively. Only phenyl-lactate reduced acetate incorporation into the resting and stimulated lymphocyte, by 20% and 34% respectively. 4. Glucose incorporation into leucocyte lipid was unaffected by phenylalanine, phenylpyruvate and phenyl-lactate. Only phenyl-lactate inhibited (46%) the production of CO2 from glucose. 5. Phenylalanine and leucine incorporation into trichloroacetic acid-insoluble material of resting and stimulated lymphocytes was inhibited by phenyl-lactate (10–42%), phenylpyruvate (27–57%) and phenylacetate (19–39%). 6. Uridine incorporation into resting and stimulated cells was inhibited by phenyl-lactate (22–26%), phenylpyruvate (42–52%) and phenylacetate (20%). 7. Thymidine incorporation into resting lymphocytes was reduced by phenyl-lactate, phenylpyruvate, phenylacetate and phenylalanine by 12–26%. Incorporation into the stimulated cell was inhibited by phenylpyruvate and phenyl-lactate (90%) and phenylacetate (66%). 8. Phenylalanine inhibited lymphocyte pyruvate kinase and phenylpyruvate inhibited citrate synthetase. 9. These results are compared with published data relating to experimental hyperphenylalaninaemia and the effects of these metabolites on nervous tissue in vitro.

Radiometric Assay of Citrate Condensing Enzyme (Citrate Synthetase) in Liver Tissue and Mitochondria

1973 ◽  
Vol 19 (10) ◽  
pp. 1106-1111 ◽  
Author(s):  
Padmakar K Dixit ◽  
Raul Cuestas
Keyword(s):  
Liver Mitochondria ◽  
Spectrophotometric Assay ◽  
Synthetase Activity ◽  
Carbon 14 ◽  
Coupling Reagent ◽  
Radiometric Assay ◽  
Oxidative Bromination ◽  
Isolated Liver ◽  
Citrate Synthetase ◽  
Condensing Enzyme

Abstract Citrate synthetase activity was determined in samples of commercially available citrate condensing enzyme. We measured the amount of radioactive citrate formed from the condensation of carbon-14 labeled acetyl CoA and oxaloacetate. The labeled citrate was oxidized by oxidative bromination; 14CO2 evolved was collected and represented the amount of citrate synthesized. Enzyme activity as low as 10-4 µmol/min was measured reproducibly with this procedure. Results obtained with this assay compared closely with those of a widely used spectrophotometric assay in which Ellman’s SH-coupling reagent [5,5-dithio-bis-(2-nitrobenzoate)] is coupled with CoA released during the reaction. Accuracy of labeled citrate determination in the presence of labeled acetate or pyruvate was excellent. The method can be used to determine citrate synthetase activity in skeletal muscle, liver, and isolated liver mitochondria, or to study the fate of labeled citrate injected into animals.

Acetoin and Diacetyl Production by Lactobacillus plantarum Able to Use Citrate

1983 ◽  
Vol 46 (6) ◽  
pp. 503-505 ◽  
Author(s):  
S. M. EL-GENDY ◽  
H. ABDEL-GALIL ◽  
Y. SHAHIN ◽  
F. Z. HEGAZI
Keyword(s):  
Lactobacillus Plantarum ◽  
Lactobacillus Casei ◽  
Coenzyme A ◽  
Cell Suspensions ◽  
Reversible Reaction ◽  
Acetyl Coenzyme A ◽  
Whole Cell ◽  
Acetyl Coenzyme ◽  
Molar Basis ◽  
Citrate Synthetase

Whole-cell suspensions of Lactobacillus plantarum grown on lactose in the presence of citrate did not produce acetoin and diacetyl (AD) (D) from citrate in succinate buffer, pH 4.4 unless both a source of energy and nitrogen was present, but did from pyruvate. The total AD and the amount of D, produced by citrate-grown cells, from citrate were about two times the amounts formed from pyruvate, calculated on a molar basis. It appears, that AD are formed not only from pyruvate resulting from cleavage of citrate but also from acetyl-coenzyme A arising during a probable breakdown of citrate in a reversible reaction of citrate synthetase. Neither acetate nor acetaldehyde had any effect on the total AD or the amount of D produced from pyruvate by pyruvate-grown cells. The rates of AD production from pyruvate by whole-cell suspensions of pyruvate-grown L. plantarum and Streptococcus subsp. diacetylactis represented only 69.7 and 6.6%, respectively, of that produced by Lactobacillus casei. These were 0.075 μmoles/mg dry wt−1 ml−1 min−1 for L. casei, 0.053 for L. plantarum and 0.005 for S. lactis subsp. diacetylactis.

Activation of Citrate Synthetase by Indoleacetic Acid

Nature ◽  
1969 ◽  
Vol 224 (5215) ◽  
pp. 184-185 ◽  
Author(s):  
B. L. W. BROCK ◽  
R. A. FLETCHER
Keyword(s):  
Indoleacetic Acid ◽  
Citrate Synthetase

Acetoin and Diacetyl Formation by Streptococcus lactis subsp. diacetylactis DRC3

1983 ◽  
Vol 46 (7) ◽  
pp. 601-604
Author(s):  
S. M. EL-GENDY ◽  
H. ABDEL-GALIL ◽  
Y. SHAHIN ◽  
F. Z. HEGAZI
Keyword(s):  
Cetylpyridinium Chloride ◽  
Reversible Reaction ◽  
Optimum Conditions ◽  
Acetyl Coa ◽  
Streptococcus Lactis ◽  
Molar Basis ◽  
Citrate Synthetase

Cells of Streptococcus lactis subsp. diacetylactis DRC3 which had been grown on lactose in the presence of citrate were unable to form acetoin and diacetyl (AD) from citrate when suspended in succinate buffer, pH 4.4. Inclusion of both a source of energy and nitrogen in the buffer was necessary for AD formation. Concentrations of AD and D at pH 4.4 were about five and three times the concentrations at pH 6.4. The amounts of AD and D from citrate were about eight and two times those from pyruvate, calculated on a molar basis. It appears that D, at least, is formed not only from pyruvate arising during citrate cleavage, but also from acetyl-CoA resulting from a probable citrate breakdown in a reversible reaction of a citrate synthetase. The rate of AD formation, under optimum conditions, was 0.047 μmoles mg (dry wt−1) cells ml−1 min−1. Pyruvate-grown cells produced little AD from pyruvate. AD production was inhibited partly by acetate and completely by acetaldehyde. Cetylpyridinium chloride at a concentration higher than μg ml−1 suppressed AD production from citrate because of the absence of interfering compounds normally present in milk.

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