scholarly journals The tricarboxylic acid cycle in Dictyostelium discoideum. II. Evaluation of model consistency and robustness

1992 ◽  
Vol 267 (32) ◽  
pp. 22919-22925 ◽  
Author(s):  
F Shiraishi ◽  
M.A. Savageau
Keyword(s):  
Dictyostelium Discoideum ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Model Consistency

scholarly journals The tricarboxylic acid cycle in Dictyostelium discoideum. A model of the cycle at preculmination and aggregation

1979 ◽  
Vol 184 (3) ◽  
pp. 589-597 ◽  
Author(s):  
P J Kelly ◽  
J K Kelleher ◽  
B E Wright
Keyword(s):  
Dictyostelium Discoideum ◽  
Adenylate Kinase ◽  
Malic Enzyme ◽  
Tricarboxylic Acid Cycle ◽  
Specific Radioactivity ◽  
Tricarboxylic Acid ◽  
Complete Oxidation ◽  
Flux Rate ◽  
Acid Cycle ◽  
Preliminary Model

A preliminary model of tricarboxylic acid-cycle activity in Dictyostelium discoideum is presented. Specific-radioactivity labelling patterns of intra- and extra-mitochondrial pools are simulated by this model and compared with the experimental data. The model arrived at by this method shows the following features. (1) The cycle flux rate is approx. 0.4 mM/min. (2) Both fumarate and malate are compartmentalized at approx. 1:5 between cycle pools and non-cycle pools. These may represent mitochondrial and cytoplasmic pools. Citrate is compartmentalized at 1:10. Succinate appears to exist in three compartments, two of which become labelled by [14C]glutamate and only one by [14C]aspartate (3) Two pools of aspartate with two associated pools of oxaloacetate are necessary for simulation. (4) Exchange between the cycle and non-cycle pools of both citrate and fumarate occurs at very low rates of about 0.003 mM/min, whereas exchange between the malate pools is about 0.004 mM/min. The exchange reaction glutamate in equilibrium 2-oxoglutarate runs at approx. 15 times the cycle flux. (5) A reaction catalysed by “malic” enzyme is included in the model, as this reaction is necessary for complete oxidation of amino acid substrates. (6) Calculation of the ATP yield from the model is consistent with earlier estimates of ATP turnover if the activity of adenylate kinase is considered.

scholarly journals The tricarboxylic acid cycle in Dictyostelium discoideum. Metabolite concentrations, oxygen uptake and 14c-labelled amino acid labelling patterns

1979 ◽  
Vol 184 (3) ◽  
pp. 581-588 ◽  
Author(s):  
P J Kelly ◽  
J K Kelleher ◽  
B E Wright
Keyword(s):  
Amino Acid ◽  
Oxygen Uptake ◽  
Dictyostelium Discoideum ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Stage Of Development ◽  
Metabolite Concentrations

Some aspects of tricarboxylic acid-cycle activity during differentiation and aging in Dictyostelium discoideum were examined. The concentrations of glutamate, aspartate, alanine, citrate, 2-oxoglutarate, succinate, fumarate, malate, oxaloacetate, pyruvate and acetyl-CoA were determined at four stages over the course of differentiation. The rate of O2 utilization was also determined over differentiation. In addition, experiments are described in which the specific radioactivities of citrate, 2-oxoglutarate, succinate, fumarate and malate were determined during a 30 min labelling of cells from the preculmination stage of development with [14C]glutamate, [14C]aspartate or [14C]alanine. A similar experiment was also performed with cells from the aggregation stage of development using [14C]glutamate.

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