A simple method for measuring the tricarboxylic acid cycle and pentose phosphate pathway in adipose tissue

1978 ◽  
Vol 84 (2) ◽  
pp. 609-614 ◽  
Author(s):  
C.John Garratt
Keyword(s):  
Adipose Tissue ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Simple Method ◽  
Acid Cycle

scholarly journals Glucose metabolism and its regulation in pieces of perirenal adipose tissue from foetal lambs

1983 ◽  
Vol 210 (3) ◽  
pp. 677-683 ◽  
Author(s):  
J P Robertson ◽  
A Faulkner ◽  
R G Vernon
Keyword(s):  
Adipose Tissue ◽  
Glucose Metabolism ◽  
Pyruvate Dehydrogenase ◽  
Glucose Utilization ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Near Term ◽  
Glucose 6 Phosphate Dehydrogenase

1. The following were measured in pieces of perirenal adipose tissue obtained from foetal lambs at about 120 days of gestation or within 3 days of term, and 9-month-old sheep: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO2 and the proportions contributed by the pentose phosphate cycle, pyruvate dehydrogenase and the tricarboxylic acid cycle; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase and pyruvate dehydrogenase. 2. The total rate of glucose utilization was lower in pieces of adipose tissue from near-term lambs than 120-day foetal lambs and the pattern of glucose metabolism differed, with, for example, a much smaller proportion of glucose carbon being used for fatty acid synthesis, whereas a greater proportion of glucose oxidation occurred via the tricarboxylic acid cycle in the near-term lambs. In general, these differences in glucose metabolism were not associated with differences in the activities of the various enzymes listed above. 3. The rates of glucose utilization per fat-cell by 120-day foetal lambs and 9-month-old sheep were very similar but, again, the proportions metabolized to the various products differed. In particular, there was a smaller proportion of glucose oxidized via the pentose phosphate cycle and a greater proportion oxidized via pyruvate dehydrogenase and the tricarboxylic acid cycle in adipose tissue from foetal lambs. These differences were matched by a lower activity of glucose 6-phosphate dehydrogenase and a higher pyruvate dehydrogenase activity in fat-cells from the foetal lambs.

Upregulation of Pentose Phosphate Pathway and Preservation of Tricarboxylic Acid Cycle Flux after Experimental Brain Injury

2005 ◽  
Vol 22 (10) ◽  
pp. 1052-1065 ◽  
Author(s):  
Brenda L. Bartnik ◽  
Richard L. Sutton ◽  
Masamichi Fukushima ◽  
Neil G. Harris ◽  
David A. Hovda ◽  
...  
Keyword(s):  
Brain Injury ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle

scholarly journals Maximum activities of key enzymes of glycolysis, glutaminolysis, pentose phosphate pathway and tricarboxylic acid cycle in normal, neoplastic and suppressed cells

1990 ◽  
Vol 265 (2) ◽  
pp. 503-509 ◽  
Author(s):  
M Board ◽  
S Humm ◽  
E A Newsholme
Keyword(s):  
Pyruvate Kinase ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Neoplastic Cells ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Metastatic Cells ◽  
Tumorigenic Cells

1. Maximal activities of some key enzymes of glycolysis, the pentose phosphate pathway, the tricarboxylic acid cycle and glutaminolysis were measured in homogenates from a variety of normal, neoplastic and suppressed cells. 2. The relative activities of hexokinase and 6-phosphofructokinase suggest that, particularly in neoplastic cells, in which the capacity for glucose transport is high, hexokinase could approach saturation in respect to intracellular glucose; consequently, hexokinase and phosphofructokinase could play an important role in the regulation of glycolytic flux in these cells. 3. The activity of pyruvate kinase is considerably higher in tumorigenic cells than in non-tumorigenic cells and higher in metastatic cells than in tumorigenic cells: for non-tumorigenic cells the activities range from 28.4 to 574, for tumorigenic cells from 899 to 1280, and for metastatic cells from 1590 to 1627 nmol/min per mg of protein. 4. The ratio of pyruvate kinase activity to 2 x phosphofructokinase activity is very high in neoplastic cells. The mean is 22.4 for neoplastic cells, whereas for muscle from 60 different animals it is only 3.8. 5. Both citrate synthase and isocitrate dehydrogenase activities are present in non-neoplastic and neoplastic cells, suggesting that the full complement of tricarboxylic-acid-cycle enzymes are present in these latter cells. 6. In neoplastic cells, the activity of glutaminase is similar to or greater than that of hexokinase, which suggests that glutamine may be as important as glucose for energy generation in these cells.

scholarly journals Biochemical adaptation in rat liver in response to marginal oxygen toxicity

1971 ◽  
Vol 125 (2) ◽  
pp. 439-447 ◽  
Author(s):  
R. R. Gorman ◽  
J. P. Jordan ◽  
J. B. Simmons ◽  
D. P. Clarkson
Keyword(s):  
Sea Level ◽  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Oxygen Toxicity ◽  
Liver Glycogen ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Biochemical Adaptation ◽  
Glucose 6 Phosphate Dehydrogenase

1. Hepatic glucose 6-phosphate dehydrogenase activity was increased in rats exposed to 5lb/in2 (equivalent to 27000ft), 100% O2 when compared with control animals in a 14.7lb/in2 (sea level), air environment. Glyceraldehyde 3-phosphate dehydrogenase, isocitrate dehydrogenase, and succinate dehydrogenase were not affected by the 5lb/in2, 100% O2 environment. 2. Animals exposed to the hyperoxic environment consumed food, expired CO2 and gained weight at the same rate as normoxic control animals. Additionally, blood glucose and liver glycogen concentrations were unchanged in the hyperoxic animals. The only readily apparent physiological difference in the hyperoxic animals was a decreased haematocrit. 3. The increase in glucose 6-phosphate dehydrogenase was eliminated by the injection of actinomycin D or cycloheximide. 4. Expiration of 14CO2 from [1-14C]glucose was approximately the same in hyperoxic and normoxic rats. However, 14CO2 expiration from [6-14C]glucose was markedly decreased in the animals exposed to the hyperoxic environment. 5. Calculations of the relative importance of the pentose phosphate pathway versus the tricarboxylic acid cycle plus glycolysis indicated that the livers from animals in the 5lb/in2, 100% O2 environment metabolized twice as much carbohydrate by way of the pentose phosphate pathway as did those from the sea-level air control animals. 6. In livers of rats exposed to 5lb/in2, 100% O2 the concentrations of pyruvate, citrate and 2-oxoglutarate were increased, that of isocitrate was slightly elevated, whereas the concentrations of succinate, fumarate and malate were decreased. 7. An inactivation of both tricarboxylic acid cycle lipoate-containing dehydrogenases, pyruvate and 2-oxoglutarate, under hyperoxic conditions is proposed. 8. The adaptive significance of the induction of glucose 6-phosphate dehydrogenase and the resultant production of NADPH under hyperoxic conditions is discussed.

scholarly journals Dual metabolomic profiling uncovers Toxoplasma manipulation of the host metabolome and the discovery of a novel parasite metabolic capability

2018 ◽  
Author(s):  
William J. Olson ◽  
David Stevenson ◽  
Daniel Amador-Noguez ◽  
Laura J. Knoll
Keyword(s):  
Pentose Phosphate Pathway ◽  
Time Course ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Obligate Intracellular ◽  
Host Parasite ◽  
Host Metabolism ◽  
Sedoheptulose Bisphosphatase

AbstractThe obligate intracellular parasite Toxoplasma gondii is auxotrophic for several key metabolites and must scavenge these from the host. It is unclear how Toxoplasma manipulates host metabolism for its overall growth rate and non-essential metabolites. To address this question, we measured changes in the joint host-parasite metabolome over a time course of infection. Host and parasite transcriptomes were simultaneously generated to determine potential changes in metabolic enzyme levels. Toxoplasma infection increased activity in multiple metabolic pathways, including the tricarboxylic acid cycle, the pentose phosphate pathway, glycolysis, amino acid synthesis, and nucleotide metabolism. Our analysis indicated that changes in some pathways, such as the tricarboxylic acid cycle, derive from the parasite, while changes in others, like the pentose phosphate pathway, were host and parasite driven. Further experiments led to the discovery of a Toxoplasma enzyme, sedoheptulose bisphosphatase, which funnels carbon from glycolysis into ribose synthesis through a energetically driven dephosphorylation reaction. This second route for ribose synthesis resolves a conflict between the Toxoplasma tricarboxylic acid cycle and pentose phosphate pathway, which are both NADP+ dependent. During periods of high energetic and ribose need, the competition for NADP+ could result in lethal redox imbalances. Sedoheptulose bisphosphatase represents a novel step in Toxoplasma central carbon metabolism that allows Toxoplasma to satisfy its ribose demand without using NADP+. Sedoheptulose bisphosphatase is not present in humans, highlighting its potential as a drug target.Author SummaryThe obligate intracellular parasite Toxoplasma is commonly found among human populations worldwide and poses severe health risks to fetuses and individuals with AIDS. While some treatments are available they are limited in scope. A possible target for new therapies is Toxoplasma’s limited metabolism, which makes it heavily reliant in its host. In this study, we generated a joint host/parasite metabolome to better understand host manipulation by the parasite and to discover unique aspects of Toxoplasma metabolism that could serve as the next generation of drug targets. Metabolomic analysis of Toxoplasma during an infection time course found broad activation of host metabolism by the parasite in both energetic and biosynthetic pathways. We discovered a new Toxoplasma enzyme, sedoheptulose bisphosphatase, which redirects carbon from glycolysis into ribose synthesis. Humans lack sedoheptulose bisphosphatase, making it a potential drug target. The wholesale remodeling of host metabolism for optimal parasite growth is also of interest, although the mechanisms behind this host manipulation must be further studied before therapeutic targets can be identified.

Biosynthesis of ε-rhodomycinone from glucose by Streptomyces C5 and comparison with intermediary metabolism of other polyketide-producing streptomycetes

1988 ◽  
Vol 34 (11) ◽  
pp. 1235-1240 ◽  
Author(s):  
Michael L. Dekleva ◽  
William R. Strohl
Keyword(s):  
Pentose Phosphate Pathway ◽  
Enzyme Activities ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Anthracycline Antibiotics ◽  
Glyoxylate Bypass ◽  
Acid Cycle ◽  
Minor Contribution ◽  
A Minor

The catabolism of glucose by Streptomyces C5, a producer of anthracycline antibiotics, was investigated to determine the pathways that supply precursors for anthracycline biosynthesis. Carbons for the biosynthesis of ε-rhodomycinone, an anthracycline aglycone, from radiolabelled glucose were derived primarily from the Embden–Meyerhof–Parnas pathway, with a minor contribution from the pentose phosphate pathway. Furthermore, the anthracycline-producing strain, Streptomyces C5, as well as Streptomyces aureofaciens and Streptomyces lividans, strains that produce nonanthracycline polyketide antibiotics, displayed enzyme activities indicative of the Embden–Meyerhof–Parnas and pentose phosphate glycolytic pathways. As determined from labelling patterns, Streptomyces C5 apparently has a complete tricarboxylic acid cycle, but does not have a glyoxylate bypass pathway.

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