scholarly journals Effects of starvation on the maximal activities of some glycolytic and citric acid-cycle enzymes and glutaminase in mucosa of the small intestine of the rat

1982 ◽  
Vol 206 (1) ◽  
pp. 169-172 ◽  
Author(s):  
Leszek Budohoski ◽  
R. A. John Challis ◽  
Eric A. Newsholme
Keyword(s):  
Small Intestine ◽  
Citric Acid ◽  
Glucose Metabolism ◽  
Citric Acid Cycle ◽  
Fructose Bisphosphatase ◽  
Acid Cycle ◽  
Absorptive Cells ◽  
Citric Acid Cycle Enzymes

Starvation decreases activities of some glycolytic and citric acid-cycle enzymes, and increases those of glucose 6-phosphatase and fructose bisphosphatase, whereas that of glutaminase is unchanged. These findings may be of significance for the control of glucose metabolism in the absorptive cells of the intestine.

scholarly journals The activities of the citric acid-cycle enzymes in rat bone-marrow cells

1968 ◽  
Vol 108 (3) ◽  
pp. 413-415
Author(s):  
Eugene Goldwasser
Keyword(s):  
Bone Marrow ◽  
Citric Acid ◽  
Citric Acid Cycle ◽  
Citrate Synthase ◽  
Bone Marrow Cells ◽  
Mitochondrial Enzymes ◽  
Acid Cycle ◽  
Citric Acid Cycle Enzymes ◽  
Rat Bone ◽  
Marrow Cells

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, α-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.

Enzymes of Glucose Metabolism in the Caecum of the Marine Borer Bankia setacea

1970 ◽  
Vol 27 (6) ◽  
pp. 1141-1146 ◽  
Author(s):  
D. L. Liu ◽  
C. C. Walden
Keyword(s):  
Citric Acid ◽  
Glucose Metabolism ◽  
Enzyme Activities ◽  
Citric Acid Cycle ◽  
Acid Cycle ◽  
Modified Embden Meyerhof Pathway

The caecum of the marine borer Bankia setacea was found to contain the enzymes for a modified Embden–Meyerhof pathway, a pentose cycle, and a complete citric acid cycle. The pathways are linked to the digestion of cellulose by the enzyme cellobiase. Significant numbers of bacteria were not detected in the caecum of the borer. Enzyme activities in the citric acid cycle indicate a biosynthesis role for the caecum.

The extraordinary mitochondrion and unusual citric acid cycle in Trypanosoma brucei

2005 ◽  
Vol 33 (5) ◽  
pp. 967-971 ◽  
Author(s):  
J.J. van Hellemond ◽  
F.R. Opperdoes ◽  
A.G.M. Tielens
Keyword(s):  
Citric Acid ◽  
Energy Metabolism ◽  
Trypanosoma Brucei ◽  
Citric Acid Cycle ◽  
Clinical Importance ◽  
African Trypanosomes ◽  
Acid Cycle ◽  
Fermentative Metabolism ◽  
Influence Of Substrate ◽  
Citric Acid Cycle Enzymes

African trypanosomes are parasitic protozoa that cause sleeping sickness and nagana. Trypanosomes are not only of scientific interest because of their clinical importance, but also because these protozoa contain several very unusual biological features, such as their specially adapted mitochondrion and the compartmentalization of glycolytic enzymes in glycosomes. The energy metabolism of Trypanosoma brucei differs significantly from that of their hosts and changes drastically during the life cycle. Despite the presence of all citric acid cycle enzymes in procyclic insect-stage T. brucei, citric acid cycle activity is not used for energy generation. Recent investigations on the influence of substrate availability on the type of energy metabolism showed that absence of glycolytic substrates did not induce a shift from a fermentative metabolism to complete oxidation of substrates. Apparently, insect-stage T. brucei use parts of the citric acid cycle for other purposes than for complete degradation of mitochondrial substrates. Parts of the cycle are suggested to be used for (i) transport of acetyl-CoA units from the mitochondrion to the cytosol for the biosynthesis of fatty acids, (ii) degradation of proline and glutamate to succinate, (iii) generation of malate, which can then be used for gluconeogenesis. Therefore the citric acid cycle in trypanosomes does not function as a cycle.

Organization of citric acid cycle enzymes into a multienzyme cluster

FEBS Letters ◽  
1986 ◽  
Vol 201 (2) ◽  
pp. 267-270 ◽  
Author(s):  
Sarah J. Barnes ◽  
P.D.J. Weitzman
Keyword(s):  
Citric Acid ◽  
Citric Acid Cycle ◽  
Acid Cycle ◽  
Citric Acid Cycle Enzymes

Glucose Metabolism in the Caecum of the Marine Borer Bankia setacea

1968 ◽  
Vol 25 (5) ◽  
pp. 853-862 ◽  
Author(s):  
D. Liu ◽  
P. M. Townsley
Keyword(s):  
Citric Acid ◽  
Glucose Metabolism ◽  
Soluble Protein ◽  
Citric Acid Cycle ◽  
Digestive Organ ◽  
Acid Cycle ◽  
Wood Borer ◽  
Pentose Pathway

The degradation of uniformly labelled glucose-C14 was followed in the caeca preparations of the marine wood borer Bankia setacea (Tryon). This digestive organ was found to contain large quantities of soluble protein. Various accumulating intermediates were isolated, indicating the presence of enzymes typical of the Embden–Meyerhof pathway, the pentose pathway, the citric acid cycle, and the non-triose pathway. The presence of wood in the caeca may be required for the synthesis of glutamic and aspartic acids within the caeca. Approximately 10% of the added glucose was found in an unidentified, unstable, electronegative compound called glucose-X. The function of this compound is unknown.

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