scholarly journals THE TRICARBOXYLIC ACID CYCLE IN RHODOSPIRILLUM RUBRUM

1953 ◽  
Vol 203 (2) ◽  
pp. 815-836 ◽  
Author(s):  
Max A. Eisenberg
Keyword(s):  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle

Utilization of fructose and glutamate by Rhodospirillum rubrum

1968 ◽  
Vol 14 (5) ◽  
pp. 493-498 ◽  
Author(s):  
Margaret S. Gibson ◽  
Chih H. Wang
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Glycolytic Pathway ◽  
Light Conditions ◽  
Acid Cycle

Fructose served as sole carbon source for the growth of Rhodospirillum rubrum anaerobically under light or aerobically in the dark while glucose did not. Glucose was not utilized by the organism at all. Radiorespirometric studies, using 14C specifically labelled fructose as substrate, revealed that fructose is catabolized exclusively via the Embden–Meyerhof–Parnas (EMP) glycolytic pathway. Both L-glutamic and D-glutamic acids can be utilized by this organism, via the tricarboxylic acid cycle (TCA) pathway, under either aerobic-dark or anaerobic-light conditions.

scholarly journals Microaerophilic Cooperation of Reductive and Oxidative Pathways Allows Maximal Photosynthetic Membrane Biosynthesis in Rhodospirillum rubrum

2003 ◽  
Vol 69 (11) ◽  
pp. 6577-6586 ◽  
Author(s):  
Hartmut Grammel ◽  
Ernst-Dieter Gilles ◽  
Robin Ghosh
Keyword(s):  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Carbon Sources ◽  
Pyridine Nucleotide ◽  
Tricarboxylic Acid ◽  
Physiological Adaptation ◽  
Marker Enzyme ◽  
Photosynthetic Membrane ◽  
Acid Cycle ◽  
Microaerophilic Conditions

ABSTRACT The purple nonsulfur bacterium Rhodospirillum rubrum has been employed to study physiological adaptation to limiting oxygen tensions (microaerophilic conditions). R. rubrum produces maximal levels of photosynthetic membranes when grown with both succinate and fructose as carbon sources under microaerophilic conditions in comparison to the level (only about 20% of the maximum) seen in the absence of fructose. Employing a unique partial O2 pressure (pO2) control strategy to reliably adjust the oxygen tension to values below 0.5%, we have used bioreactor cultures to investigate the metabolic rationale for this effect. A metabolic profile of the central carbon metabolism of these cultures was obtained by determination of key enzyme activities under microaerophilic as well as aerobic and anaerobic phototrophic conditions. Under aerobic conditions succinate and fructose were consumed simultaneously, whereas oxygen-limiting conditions provoked the preferential breakdown of fructose. Fructose was utilized via the Embden-Meyerhof-Parnas pathway. High levels of pyrophosphate-dependent phosphofructokinase activity were found to be specific for oxygen-limited cultures. No glucose-6-phosphate dehydrogenase activity was detected under any conditions. We demonstrate that NADPH is supplied mainly by the pyridine-nucleotide transhydrogenase under oxygen-limiting conditions. The tricarboxylic acid cycle enzymes are present at significant levels during microaerophilic growth, albeit at lower levels than those seen under fully aerobic growth conditions. Levels of the reductive tricarboxylic acid cycle marker enzyme fumarate reductase were also high under microaerophilic conditions. We propose a model by which the primary “switching” of oxidative and reductive metabolism is performed at the level of the tricarboxylic acid cycle and suggest how this might affect redox signaling and gene expression in R. rubrum.

A COMPARISON OF THE OXIDATIVE METABOLISM OF LIGHT AND DARK GROWN RHODOSPIRILLUM RUBRUM

1956 ◽  
Vol 2 (4) ◽  
pp. 427-432 ◽  
Author(s):  
P. G. Crook ◽  
E. S. Lindstrom
Keyword(s):  
Oxidative Metabolism ◽  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Rhodopseudomonas Palustris ◽  
Succinic Dehydrogenase ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Acid Cycle ◽  
Keto Acids ◽  
Soluble Enzymes

Using a manometric or a dehydrogenase assay, activity for most of the intermediates of the tricarboxylic acid cycle was demonstrated in extracts from Rhodo spirillum rubrum grown photosynthetically (anaerobic light), heterotrophically (aerobic dark), or a combination of both (aerobic light). Dehydrogenases for succinate and α-ketoglutarate were more active in extracts from cells grown photosynthetically. Extracts from cells grown heterotrophically had the greatest oxidative activity. Succinic dehydrogenase was associated with larger macromolecular units in all extracts while the other dehydrogenases behaved as soluble enzymes. Conditions of cultivation affected the rate at which keto acids were formed from citrate. Rhodopseudomonas palustris also possessed tricarboxylic acid dehydrogenases whether grown photosynthetically or heterotrophically.

scholarly journals Effects of sevoflurane anesthesia and abdominal surgery on the systemic metabolome: a prospective observational study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yiyong Wei ◽  
Donghang Zhang ◽  
Jin Liu ◽  
Mengchan Ou ◽  
Peng Liang ◽  
...  
Keyword(s):  
Abdominal Surgery ◽  
General Anesthesia ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Metabolic Changes ◽  
Sevoflurane Anesthesia ◽  
Glutamate Metabolism ◽  
Acid Cycle ◽  
Link Type ◽  
The Mean

Abstract Background Metabolic status can be impacted by general anesthesia and surgery. However, the exact effects of general anesthesia and surgery on systemic metabolome remain unclear, which might contribute to postoperative outcomes. Methods Five hundred patients who underwent abdominal surgery were included. General anesthesia was mainly maintained with sevoflurane. The end-tidal sevoflurane concentration (ETsevo) was adjusted to maintain BIS (Bispectral index) value between 40 and 60. The mean ETsevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery was calculated for each patient. The patients were further divided into low ETsevo group (mean − SD) and high ETsevo group (mean + SD) to investigate the possible metabolic changes relevant to the amount of sevoflurane exposure. Results The mean ETsevo of the 500 patients was 1.60% ± 0.34%. Patients with low ETsevo (n = 55) and high ETsevo (n = 59) were selected for metabolomic analysis (1.06% ± 0.13% vs. 2.17% ± 0.16%, P < 0.001). Sevoflurane and abdominal surgery disturbed the tricarboxylic acid cycle as identified by increased citrate and cis-aconitate levels and impacted glycometabolism as identified by increased sucrose and D-glucose levels in these 114 patients. Glutamate metabolism was also impacted by sevoflurane and abdominal surgery in all the patients. In the patients with high ETsevo, levels of L-glutamine, pyroglutamic acid, sphinganine and L-selenocysteine after sevoflurane anesthesia and abdominal surgery were significantly higher than those of the patients with low ETsevo, suggesting that these metabolic changes might be relevant to the amount of sevoflurane exposure. Conclusions Sevoflurane anesthesia and abdominal surgery can impact principal metabolic pathways in clinical patients including tricarboxylic acid cycle, glycometabolism and glutamate metabolism. This study may provide a resource data for future studies about metabolism relevant to general anaesthesia and surgeries. Trial registration www.chictr.org.cn. identifier: ChiCTR1800014327.

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