Structural  -cell Changes and Transient Hyperglycemia in Mice Treated With Compounds Inducing Inhibited Citric Acid Cycle Enzyme Activity

Diabetes ◽  
1988 ◽  
Vol 37 (1) ◽  
pp. 89-98 ◽  
Author(s):  
L. Boquist ◽  
S. Boquist ◽  
I. Ericsson
Keyword(s):  
Enzyme Activity ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Acid Cycle ◽  
Structural Cell ◽  
Cycle Enzyme ◽  
Cell Changes

scholarly journals Another Unusual Type of Citric Acid Cycle Enzyme inHelicobacter pylori: the Malate:Quinone Oxidoreductase

2000 ◽  
Vol 182 (11) ◽  
pp. 3204-3209 ◽  
Author(s):  
Birgit Kather ◽  
Kerstin Stingl ◽  
Michel E. van der Rest ◽  
Karlheinz Altendorf ◽  
Douwe Molenaar
Keyword(s):  
Electron Transfer ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Acid Cycle ◽  
Electron Transfer Chain ◽  
Cycle Enzyme ◽  
Coa Transferase ◽  
Standard Textbook ◽  
H Pylori ◽  
Transfer Chain

ABSTRACT The only enzyme of the citric acid cycle for which no open reading frame (ORF) was found in the Helicobacter pylori genome is the NAD-dependent malate dehydrogenase. Here, it is shown that in this organism the oxidation of malate to oxaloacetate is catalyzed by a malate:quinone oxidoreductase (MQO). This flavin adenine dinucleotide-dependent membrane-associated enzyme donates electrons to quinones of the electron transfer chain. Similar to succinate dehydrogenase, it is part of both the electron transfer chain and the citric acid cycle. MQO activity was demonstrated in isolated membranes of H. pylori. The enzyme is encoded by the ORF HP0086, which is shown by the fact that expression of the HP0086 sequence from a plasmid induces high MQO activity in mqo deletion mutants of Escherichia coli or Corynebacterium glutamicum. Furthermore, this plasmid was able to complement the phenotype of the C. glutamicum mqo deletion mutant. Interestingly, the protein predicted to be encoded by this ORF is only distantly related to known or postulated MQO sequences from other bacteria. The presence of an MQO shown here and the previously demonstrated presence of a 2-ketoglutarate:ferredoxin oxidoreductase and a succinyl-coenzyme A (CoA):acetoacetyl-CoA transferase indicate that H. pylori possesses a complete citric acid cycle, but one which deviates from the standard textbook example in three steps.

scholarly journals The novel component Kgd4 recruits the E3 subunit to the mitochondrial α-ketoglutarate dehydrogenase

2014 ◽  
Vol 25 (21) ◽  
pp. 3342-3349 ◽  
Author(s):  
Manfred Heublein ◽  
Miguel A. Burguillos ◽  
F. Nora Vögtle ◽  
Pedro F. Teixeira ◽  
Axel Imhof ◽  
...  
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Respiratory Chain Complexes ◽  
Acid Cycle ◽  
Cycle Enzyme ◽  
Chain Complexes ◽  
Mitochondrial Ribosome ◽  
A Subunit ◽  
Biochemical Analyses ◽  
Ketoglutarate Dehydrogenase

The mitochondrial citric acid cycle is a central hub of cellular metabolism, providing intermediates for biosynthetic pathways and channeling electrons to the respiratory chain complexes. In this study, we elucidated the composition and organization of the multienzyme complex α-ketoglutarate dehydrogenase (α-KGDH). In addition to the three classical E1-E3 subunits, we identified a novel component, Kgd4 (Ymr31/MRPS36), which was previously assigned to be a subunit of the mitochondrial ribosome. Biochemical analyses demonstrate that this protein plays an evolutionarily conserved role in the organization of mitochondrial α-KGDH complexes of fungi and animals. By binding to both the E1-E2 core and the E3 subunit, Kgd4 acts as a molecular adaptor that is necessary to a form a stable α-KGDH enzyme complex. Our work thus reveals a novel subunit of a key citric acid–cycle enzyme and shows how this large complex is organized.

Effects of Exercise, Training, and Diet on Muscle Citric Acid Cycle Enzyme Activity

1973 ◽  
Vol 51 (6) ◽  
pp. 849-854 ◽  
Author(s):  
G. Lynis Dohm ◽  
Richard L. Huston ◽  
E. Wayne Askew ◽  
H. Lee Fleshood
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Citrate Synthase ◽  
Exhaustive Exercise ◽  
High Fat ◽  
Acid Cycle ◽  
Cycle Enzyme ◽  
High Fat Diets ◽  
Citric Acid Cycle Enzymes ◽  
Fat Diets

The effects of training, exhaustive exercise, and diet on the activity of skeletal muscle citric acid cycle enzymes were studied. Training increased the activities of all cycle enzymes. Exhaustion of trained rats resulted in lowered activities of NAD-specific isocitrate dehydrogenase, succinate dehydrogenase, and cytochrome oxidase but citrate synthase and malate dehydrogenase were unaffected. The enzyme activities in untrained muscle were not changed by exhaustive exercise. High carbohydrate and high fat diets did not alter citric acid cycle activities in trained rested or untrained rested rats and did not moderate or accentuate the effects of exhaustive exercise. The results indicate that muscle citric acid cycle activity is increased by training and decreased by exhaustion of trained animals.

ENZYMOLOGISCHE STUDIEN AM ARRHENOBLASTOM

1971 ◽  
Vol 67 (3) ◽  
pp. 577-589 ◽  
Author(s):  
H. Brandau ◽  
L. Brandau
Keyword(s):  
Enzyme Activity ◽  
Citric Acid ◽  
Enzyme Activities ◽  
Citric Acid Cycle ◽  
Hydroxysteroid Dehydrogenase ◽  
Pentose Phosphate ◽  
Testosterone Metabolism ◽  
Acid Cycle ◽  
Enzyme Activity Pattern ◽  
Pentose Phosphate Shunt

ABSTRACT In an arrhenoblastoma of a 24 years old female patient the enzyme activities of the intermediary carbonhydrate metabolism, the citric acid cycle, the glycerophosphate cycle, the pentose-phosphate shunt as well as the steroid-dehydrogenases were measured quantitatively and localized histochemically. The striking high activities of the glycolytic enzymes, the presence of steroid-dehydrogenases and the only moderately increased enzyme activities of the citric acid cycle in comparison with the stroma ovarii identify the arrhenoblastoma as a tissue with steroid hormonal metabolism. High activities of the mentioned enzymes and especially the activities of the steroid-dehydrogenases were localized histochemically only in Leydig-cell-like cells. Therefore these cells may be considered as structures of steroid-biogenesis. The enzyme activity pattern of the steroiddehydrogenases illuminates the biogenetic pathways of androgens. The low activities of the 17β-hydroxysteroid-dehydrogenase in this tissue in comparison with other steroid producing tissues indicate a special testosterone metabolism.

Aerobic adaptation in yeast. IV. Alterations in enzyme synthesis during anaerobic–aerobic transitions in exponentially growing cultures

1975 ◽  
Vol 21 (6) ◽  
pp. 869-876 ◽  
Author(s):  
A. J. S. Ball ◽  
Rita M. Bruver ◽  
E. R. Tustanoff
Keyword(s):  
Phase Transition ◽  
Citric Acid ◽  
Enzyme Activities ◽  
Citric Acid Cycle ◽  
Enzyme Synthesis ◽  
Acid Cycle ◽  
Cycle Enzyme ◽  
Yeast Cultures ◽  
Step Down ◽  
In Cells

As a corollary to the metabolite data obtained from yeast cultures undergoing an exponential anaerobic–aerobic phase transition, levels of various glycolytic and citric acid cycle enzyme activities have been monitored in these cells. The relation of the changes in these enzyme activities in cells grown on either glucose or galactose is discussed in light of different metabolic postures these cells demonstrate as a result of their transitions.A general discussion is presented which compares the results obtained in this series of papers from both step-down and exponential transfer experiments and relates these data to control of mitochondriogenesis in yeast.

Acute Carnosine Administration Increases Respiratory Chain Complexes and Citric Acid Cycle Enzyme Activities in Cerebral Cortex of Young Rats

2015 ◽  
Vol 53 (8) ◽  
pp. 5582-5590 ◽  
Author(s):  
Levy W. Macedo ◽  
José H. Cararo ◽  
Soliany G. Maravai ◽  
Cinara L. Gonçalves ◽  
Giovanna M. T. Oliveira ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Citric Acid ◽  
Respiratory Chain ◽  
Enzyme Activities ◽  
Citric Acid Cycle ◽  
Respiratory Chain Complexes ◽  
Acid Cycle ◽  
Cycle Enzyme ◽  
Young Rats ◽  
Chain Complexes

EFFECT OF SERUM GONADOTROPHIN ON DEHYDROGENASES OF THE CITRIC ACID CYCLE IN THE OVARY OF THE RAT

1963 ◽  
Vol 42 (4) ◽  
pp. 480-484 ◽  
Author(s):  
B. Eckstein ◽  
R. Landsberg
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Age Groups ◽  
Succinic Dehydrogenase ◽  
Immature Rat ◽  
Acid Cycle ◽  
Immature Rats ◽  
Rat Ovary

ABSTRACT The succinic, malic and isocitric dehydrogenases in the ovary of immature and mature, normal and serum gonadotrophin injected rats were examined. The Qo2 of these enzymes were markedly enhanced in the gonadotrophin injected rats of both age groups, except in the case of succinic dehydrogenase in the ovary of the immature rats, where a slight non-significant decrease was noted. It is concluded that in the mature rat ovary, gonadotrophin administration stimulates the activity of all the examined dehydrogenases of the citric acid cycle, whereas in the immature rat ovary, at least the isocitric- and malic dehydrogenases are thus stimulated.

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