Effect ofEchinococcus multilocularison the origin of acetyl-CoA entering the tricarboxylic acid cycle in host liver

2002 ◽  
Vol 76 (1) ◽  
pp. 31-36 ◽  
Author(s):  
C. Kepron ◽  
M. Novak ◽  
B.J. Blackburn
Keyword(s):  
Carbohydrate Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Meriones Unguiculatus ◽  
Host Liver ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
A Value ◽  
Alveolar Hydatid Disease ◽  
And Control

AbstractCarbon-13 nuclear magnetic resonance (NMR) spectroscopy was employed to investigate alterations in hepatic carbohydrate metabolism inMeriones unguiculatusinfected withEchinococcus multilocularis. Following portal vein injections of an equimolar mixture of ]#x005B;1,2-13C2]acetate and [3-13C]lactate, perchloric acid extracts of the livers were prepared and NMR spectra obtained. Isotopomer analysis using glutamate resonances in these spectra showed that the relative contributions of endogenous and exogenous substrates to the acetyl-CoA entering the tricarboxylic acid cycle differed significantly between infected and control groups. The mole fraction of acetyl-CoA that was derived from endogenous, unlabelled sources (FU) was 0.50±0.10 in controls compared to 0.34±0.04 in infected animals. However, the fraction of acetyl-CoA derived from [3-13C]lactate (FLL) was larger in livers of infected animals than those from controls with values of 0.27±0.04 and 0.18±0.04, respectively. Similarly, the fraction of acetyl-CoA derived from [1,2-13C2]acetate (FLA) was larger in livers of infected animals compared to those in controls; the fractions were 0.38±0.01 and 0.32±0.07, respectively. The ratio of FLA:FLLwas significantly smaller in the infected group with a value of 1.42±0.18 compared to 1.74±0.09 for the controls. These results indicate that alveolar hydatid disease has a pronounced effect on the partitioning of substrates within the pathways of carbohydrate metabolism in the host liver.

13C isotopomer model for estimation of anaplerotic substrate oxidation via acetyl-CoA

1996 ◽  
Vol 271 (4) ◽  
pp. E788-E799 ◽  
Author(s):  
F. M. Jeffrey ◽  
C. J. Storey ◽  
A. D. Sherry ◽  
C. R. Malloy
Keyword(s):  
Biochemical Analysis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Propionate Metabolism ◽  
13C Nuclear Magnetic Resonance ◽  
Isotopomer Analysis ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Anaplerotic Pathway

A previous model using 13C nuclear magnetic resonance isotopomer analysis provided for direct measurement of the oxidation of 13C-enriched substrates in the tricarboxylic acid cycle and/or their entry via anaplerotic pathways. This model did not allow for recycling of labeled metabolites from tricarboxylic acid cycle intermediates into the acetyl-CoA pool. An extension of this model is now presented that incorporates carbon flow from oxaloacetate or malate to acetyl-CoA. This model was examined using propionate metabolism in the heart, in which previous observations indicated that all of the propionate consumed was oxidized to CO2 and water. Application of the new isotopomer model shows that 2 mM [3-13C]propionate entered the tricarboxylic acid cycle as succinyl-CoA (an anaplerotic pathway) at a rate equal to 52% of tricarboxylic acid cycle turnover and that all of this carbon entered the acetyl-CoA pool and was oxidized. This was verified using standard biochemical analysis; from the rate (mumol.min-1.g dry wt-1) of propionate uptake (4.0 +/- 0.7), the estimated oxygen consumption (24.8 +/- 5) matched that experimentally determined (24.4 +/- 3).

Carbohydrate metabolism in Acanthamoeba castellanii. 1. The activity of key enzymes and [14C]-glucose metabolism

1973 ◽  
Vol 19 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
Lansing M. Prescott ◽  
Harold E. Hoyme ◽  
Darlene Crockett ◽  
Elena Hui
Keyword(s):  
Carbohydrate Metabolism ◽  
Citrate Synthase ◽  
Tricarboxylic Acid Cycle ◽  
Fumarate Hydratase ◽  
Acanthamoeba Castellanii ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Glyceraldehydephosphate Dehydrogenase

The specific activities of a number of the key enzymes involved in carbohydrate metabolism in Acanthamoeba castellanii (Neff clone I–12) have been determined. The following Embden–Meyerhof and pentose phosphate pathway enzymes were present: glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase, hexose diphosphatase, aldolase, glyceraldehydephosphate dehydrogenase, pyruvate kinase, and pyruvate-phosphate dikinase. The following tricarboxylic acid cycle enzymes were also found: citrate synthase, aconitase, isocitrate dehydrogenase, succinate dehydrogenase, fumarate hydratase, and malate dehydrogenase. The degradation of glucose-U-14C to 14CO2 was examined. Aerobic 14CO2 production from glucose-U-14C was 3.4-fold greater than anaerobic production. The data provide further evidence that the Embden–Meyerhof, pentose phosphate, and tricarboxylic acid cycle pathways are probably functional in A. castellanii.

Studies in the respiratory and carbohydrate metabolism of plant tissues XIII. The influence of oxygen at high pressures in increasing and decreasing the respiration of potatoes at 15 °C

1963 ◽  
Vol 158 (971) ◽  
pp. 143-155 ◽  
Keyword(s):  
Carboxylic Acid ◽  
Carbohydrate Metabolism ◽  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Total Carbon ◽  
Plant Tissues ◽  
Sugar Phosphate ◽  
Oxygen Inhibition ◽  
Acid Cycle

The CO 2 output of potatoes held at 15 °C in oxygen at a pressure of either 2 or 3 atm was first decreased, then increased and finally again decreased. The increase of CO 2 output was much larger than in carrots (Barker 1961); in oxygen at a pressure of 2 atm the rate of CO 2 output of potatoes was increased 4.6 fold; taking into account the accumulation of citrate, the ‘total carbon traffic’ was increased 5.6 fold in oxygen. This increase was believed to occur mainly in a pathway which was not the tricarboxylic acid cycle. As in potatoes held at 1 °C in an atmosphere of oxygen (Barker & Mapson 1955), citrate accumulated and α -ketoglutarate decreased in potatoes, held at 15 °C in oxygen at pressures of 2 or 3 atm; these changes were accepted as demonstrating the occurrence of the tri­-carboxylic acid cycle. The final decrease of CO 2 output in oxygen appeared not to be related to the occurrence of ‘blocks’ either between citrate and α -ketoglutarate or of pyruvate or α -ketoglutarate oxidases; the inhibition might be due to a shortage of sugar phosphate substrates, caused possibly by oxygen inhibition of cytochrome- c reductase. The outburst of CO 2 , which occurred in potatoes first held in oxygen and then returned to air, could not be attributed solely to oxidation of accumulated citrate.

A general model for analysis of the tricarboxylic acid cycle with use of [13C]glutamate isotopomer measurements

1994 ◽  
Vol 266 (6) ◽  
pp. E1012-E1022 ◽  
Author(s):  
J. A. Vogt ◽  
A. J. Fischman ◽  
M. Kempf ◽  
Y. M. Yu ◽  
R. G. Tompkins ◽  
...  
Keyword(s):  
13C Nmr ◽  
Tricarboxylic Acid Cycle ◽  
Nonlinear Least Squares ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Metabolic System ◽  
Acid Cycle ◽  
Nmr Data ◽  
13C Nuclear Magnetic Resonance ◽  
Model Equations

A generalized steady-state model was developed for determining tricarboxylic acid cycle fractional fluxes from 13C nuclear magnetic resonance (NMR) data. The model relates the measured mole fractions of [13C]glutamate isotopomers to the fractional fluxes and predicted mole fractions of isotopomers of oxaloacetate (OAA) and acetyl-CoA. This model includes cycling between OAA and fumarate. Fractional fluxes are determined by fitting the model equations to NMR parameters by use of nonlinear least squares. Although only fractional fluxes can be determined from 13C-NMR data, when they are combined with mass spectroscopic measurements, absolute values can be derived. A specific metabolic system represented by published 13C-NMR data from extracts of hearts perfused with [13C]acetate, [13C]pyruvate (PYR), and [13C]acetate plus [13C]PYR was used to test the model. The intensities of predicted 13C-NMR splitting patterns were compared with observed values, and there was excellent agreement between observed and predicted signal intensities. With this model, important physiological parameters, including the OAA-derived fraction of inflow to PYR, PYR-derived fraction of inflow to acetyl-CoA, citrate-derived fraction of inflow to OAA, and PYR-derived fraction of inflow to OAA, can be determined.

Sources of acetyl-CoA entering the tricarboxylic acid cycle as determined by analysis of succinate carbon-13 isotopomers

Biochemistry ◽  
1993 ◽  
Vol 32 (45) ◽  
pp. 12240-12244 ◽  
Author(s):  
John G. Jones ◽  
A. Dean Sherry ◽  
F. Mark H. Jeffrey ◽  
Charles J. Storey ◽  
Craig R. Malloy
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle

scholarly journals The activities of 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase in hearts and mammary glands from ruminants and non-ruminants

1977 ◽  
Vol 164 (2) ◽  
pp. 349-355 ◽  
Author(s):  
G Read ◽  
B Crabtree ◽  
G H Smith
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Tricarboxylic Acid Cycle ◽  
Mammary Glands ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Simple Method ◽  
Acid Cycle ◽  
Maximum Flux ◽  
Oxoglutarate Dehydrogenase

1. The activities of 2-oxoglutarate dehydrogenase (EC 1.2.4.2) were measured in hearts and mammary glands of rats, mice, rabbits, guinea pigs, cows, sheep, goats and in the flight muscles of several Hymenoptera. 2. The activity of 2-oxoglutarate dehydrogenase was similar to the maximum flux through the tricarboxylic acid cycle in vivo. Therefore measuring the activity of this enzyme may provide a simple method for estimating the maximum flux through the cycle for comparative investigations. 3. The activities of pyruvate dehydrogenase (EC 1.2.4.1) in mammalian hearts were similar to those of 2-oxoglutarate dehydrogenase, suggesting that in these tissues the tricarboxylic acid cycle can be supplied (under some conditions) by acetyl-CoA derived from pyruvate alone. 4. In the lactating mammary glands of the rat and mouse, the activities of pyruvate dehydrogenase exceeded those of 2-oxoglutarate dehydrogenase, reflecting a flux of pyruvate to acetyl-CoA for fatty acid synthesis in addition to that of oxidation via the tricarboxylic acid cycle. In ruminant mammary glands the activities of pyruvate dehydrogenase were similar to those of 2-oxoglutarate dehydrogenase, reflecting the absence of a significant flux of pyruvate to fatty acids in these tissues.

Intermediary carbohydrate metabolism in protoscoleces ofEchinococcus granulosus(horse and sheep strains) andE. multilocularis

Parasitology ◽  
1982 ◽  
Vol 84 (2) ◽  
pp. 351-366 ◽  
Author(s):  
D. P. McManus ◽  
J. D. Smyth
Keyword(s):  
Steady State ◽  
Carbohydrate Metabolism ◽  
Pyruvate Kinase ◽  
Energy Production ◽  
Alternative Energy ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
State Content

SUMMARYWith few exceptions, the specific activities of the glycolytic enzymes and the steady-state content of glycolytic and associated intermediates in protoscoleces of the horse (E.g.H) and sheep (E.g.S) strains ofEchinococcus granulosusand the closely relatedE. multilocularis(E.m.) are very similar. Phosphorylase, hexokinase, phosphofructokinase and pyruvate kinase catalyse non-equilibrium reactions and the patterns of activity for pyruvate kinase, phosphoenolpyruvate carboxykinase and malic enzyme are similar in the three organisms. The levels of tricarboxylic acid cycle intermediates inE.g.H., E.g.S. andE.m. are of the same order as those reported in tissues with an active cycle. Each has a complete sequence of cycle enzymes but there are substantial differences between the three parasites with regard to the activity of individual enzymes, The activities of NAD and NADP-linked isocitrate dehydrogenases are significantly lower inE.g.H. than inE.g.S. and particularly inE.m. which suggests that the tricarboxylic acid cycle may play a more important role in carbohydrate metabolism and energy production in the latter parasites. Nevertheless, the three organisms utilize fermentative pathways for alternative energy production, fix carbon dioxide via phosphoenolpyruvate carboxykinase and have a partial reversed tricarboxylic acid cycle. It is speculated thatin vivomore carbon will be channelled towards oxaloacetate than pyruvate at the phosphoenolpyruvate branch point. The steady state content of ATP and the ATP/AMP ratios are low in the three organisms, suggesting a low rate of ATP utilization in each.

scholarly journals Pyruvate Dehydrogenase and Tricarboxylic Acid Cycle Enzymes Are Sensitive Targets of Traumatic Brain Injury Induced Metabolic Derangement

2019 ◽  
Vol 20 (22) ◽  
pp. 5774 ◽  
Author(s):  
Giacomo Lazzarino ◽  
Angela Maria Amorini ◽  
Stefano Signoretti ◽  
Giuseppe Musumeci ◽  
Giuseppe Lazzarino ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Pyruvate Dehydrogenase ◽  
Coenzyme A ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Gene Expressions ◽  
Acetyl Coa ◽  
Metabolic Derangement ◽  
Acid Cycle

Using a closed-head impact acceleration model of mild or severe traumatic brain injury (mTBI or sTBI, respectively) in rats, we evaluated the effects of graded head impacts on the gene and protein expressions of pyruvate dehydrogenase (PDH), as well as major enzymes of mitochondrial tricarboxylic acid cycle (TCA). TBI was induced in anaesthetized rats by dropping 450 g from 1 (mTBI) or 2 m height (sTBI). After 6 h, 12 h, 24 h, 48 h, and 120 h gene expressions of enzymes and subunits of PDH. PDH kinases and phosphatases (PDK1-4 and PDP1-2, respectively), citrate synthase (CS), isocitrate dehydrogenase (IDH), oxoglutarate dehydrogenase (OGDH), succinate dehydrogenase (SDH), succinyl-CoA synthase (SUCLG), and malate dehydrogenase (MDH) were determined in whole brain extracts (n = 6 rats at each time for both TBI levels). In the same samples, the high performance liquid chromatographic (HPLC) determination of acetyl-coenzyme A (acetyl-CoA) and free coenzyme A (CoA-SH) was performed. Sham-operated animals (n = 6) were used as controls. After mTBI, the results indicated a general transient decrease, followed by significant increases, in PDH and TCA gene expressions. Conversely, permanent PDH and TCA downregulation occurred following sTBI. The inhibitory conditions of PDH (caused by PDP1-2 downregulations and PDK1-4 overexpression) and SDH appeared to operate only after sTBI. This produced almost no change in acetyl-CoA and free CoA-SH following mTBI and a remarkable depletion of both compounds after sTBI. These results again demonstrated temporary or steady mitochondrial malfunctioning, causing minimal or profound modifications to energy-related metabolites, following mTBI or sTBI, respectively. Additionally, PDH and SDH appeared to be highly sensitive to traumatic insults and are deeply involved in mitochondrial-related energy metabolism imbalance.

scholarly journals A study on the tricarboxylic acid cycle and the synthesis of acetylcholine in the lobster nerve

1970 ◽  
Vol 118 (3) ◽  
pp. 451-455 ◽  
Author(s):  
S.-C. Cheng ◽  
R. Nakamura
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Relative Magnitude ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Cleavage Enzyme ◽  
Choline Acetylase ◽  
Probable Presence ◽  
Metabolic Compartments ◽  
Slow Turnover

1. The pattern of metabolism of 14C-labelled substrates in the lobster nerve suggested a normal tricarboxylic acid cycle with a slow turnover. 2. Acetylcholine was synthesized from [2-14C]acetate, [2-14C]pyruvate and [1,5-14C]citrate, implying the presence of acetate thiokinase, choline acetylase and citrate-cleavage enzyme. 3. [2-14C]Acetate was the best precursor. 4. The formation of acetyl-CoA from citrate was limited, probably by the citrate-cleavage enzyme, although the magnitude of the reversed reactions of the tricarboxylic acid cycle was large when compared with that of the forward reactions. 5. The relative magnitude of the two pathways (acetyl-CoA and carbon dioxide fixation) in pyruvate utilization was nearly equal. 6. The probable presence of metabolic compartments in the lobster nerve is discussed.

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