scholarly journals 4-Aminobutyrate (GABA): a metabolite and signal with practical significance

Botany ◽  
2017 ◽  
Vol 95 (11) ◽  
pp. 1015-1032 ◽  
Author(s):  
Barry J. Shelp ◽  
Alan W. Bown ◽  
Adel Zarei
Keyword(s):  
Reductase Activity ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Practical Significance ◽  
Succinic Semialdehyde ◽  
Gaba Transaminase ◽  
Gaba A ◽  
Acid Cycle ◽  
Stomatal Functioning ◽  
Invertebrate Pests

We discuss the origin of 4-aminobutyrate (GABA) from glutamate and polyamines, and its subsequent catabolism to succinic semialdehyde and either succinate or 4-hydroxybutyrate. Promiscuous activities of GABA transaminase, glyoxylate/succinic semialdehyde reductases, and aldehyde dehydrogenase 10As appear to be important determinants of cross-talk among metabolic pathways during stress. Imposition of abiotic stress, as well as genetic or chemical disruption of glutamate decarboxylase, GABA transaminase, and tricarboxylic acid cycle reactions, results in non-cyclic carbon flux in the tricarboxylic acid cycle, demonstrating that stress-induced GABA metabolism is strongly linked with respiration. Metabolic generation of 4-hydroxybutyrate is probably linked to the stimulation of succinic semialdehyde reductase activity by an increasing NADPH/NADP+ ratio. We discuss the potential signaling role of GABA in various processes, including pollen tube guidance, interaction with fungal, bacterial, and invertebrate pests, and stomatal functioning, and argue that further research on short-term responses to stress is required to determine whether or not GABA functions by binding to or regulating the activity of GABA receptor molecules. Finally, we describe how emerging information about the metabolic and signaling roles of GABA is being used to improve plant defenses against biotic and abiotic stresses, and benefit human health.

scholarly journals HISTOCHEMICAL INVESTIGATIONS ON THE IN VIVO EFFECTS OF FLUORIDE ON TRICARBOXYLIC ACID CYCLE DEHYDROGENASES FROM PELARGONIUM ZONALE: PART II

1967 ◽  
Vol 15 (4) ◽  
pp. 202-206
Author(s):  
C. JAMES LOVELACE ◽  
GENE W. MILLER
Keyword(s):  
Sodium Fluoride ◽  
Reductase Activity ◽  
Tricarboxylic Acid Cycle ◽  
Leaf Tissue ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Pelargonium Zonale ◽  
Acid Cycle ◽  
In Vivo Effects

In vivo effects of fluoride on tricarboxylic acid (TCA) cycle dehydrogenase enzymes of Pelargonium zonale were studied using p-nitro blue tetrazoleum chloride. Plants were exposed to 17 ppb HF, and enzyme activities in treated plants were compared to those in controls. Leaves of control plants were incubated in 5 x 10–3 M sodium fluoride. Injuries observed in fumigation and solution experiments were similar. Leaf tissue subjected to HF or sodium fluoride evidenced less succinic p-nitro blue tetrazoleum reductase activity than did control tissue. Other TCA cycle dehydrogenase enzymes were not observably affected by the fluoride concentrations used in these experiments. Excised leaves cultured in 5 x 10–3 M sodium fluoride exhibited less succinic p-nitro blue tetrazoleum reductase activity after 24 hr than did leaves cultured in 5 x 10–3 M sodium chloride.

THE METABOLISM OF PUTRESCINE (1,4-DIAMINOBUTANE) BY MYCOBACTERIA ISOLATED FROM FISH: II. STUDIES WITH ARSENITE-INHIBITED CELLS AND CELL-FREE EXTRACTS

1967 ◽  
Vol 13 (5) ◽  
pp. 521-531 ◽  
Author(s):  
T. P. T. Evelyn
Keyword(s):  
Succinic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Significant Proportion ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Aminobutyric Acid ◽  
Succinic Semialdehyde ◽  
Amino Group ◽  
Intact Cells ◽  
Acid Cycle

Three mycobacterial strains isolated from fish degraded putrescine by a pathway in which γ-aminobutyraldehyde (Δ′-pyrroline), γ-aminobutyric acid, succinic semialdehyde, and succinic acid were intermediates. These results agree substantially with those of other workers using different microorganisms. Intact cells utilized γ-aminobutyric acid in a transaminase reaction with endogenously supplied α-ketoglutarate to produce succinic semialdehyde and glutamate. Studies with arsenite-poisoned cells showed that a significant proportion of putrescine was metabolized via pyruvate and alanine. When putrescine-1,4-14C was substrate, HCl extracts of cells contained radioactive aspartate and glutamate in addition to alanine. The further metabolism of succinate therefore proceeded in two directions: one yielding oxalacetate and α-ketoglutarate by way of the tricarboxylic acid cycle, and the other branching off the cycle to yield pyruvate. Studies with cell-free extracts suggested that putrescine nitrogen was assimilated via glutamate, which served as the amino-group donor to yield alanine and aspartate.

Enzymes of intermediary metabolism of Butyrivibrio fibrisolvens and Ruminococcus albus grown under glucose limitation

1973 ◽  
Vol 19 (9) ◽  
pp. 1119-1127 ◽  
Author(s):  
A. Kistner ◽  
J. P. Kotzé
Keyword(s):  
Reductase Activity ◽  
Tricarboxylic Acid Cycle ◽  
Defined Medium ◽  
Tricarboxylic Acid ◽  
Ruminococcus Albus ◽  
Glucose Limitation ◽  
Butyrivibrio Fibrisolvens ◽  
Acid Cycle ◽  
Phosphofructokinase Activity

A survey was made of enzyme activities in cell-free extracts prepared from one strain each of Butyrivibrio fibrisolvens and Ruminococcus albus, two anaerobic cellulolytic rumen bacteria, which had been grown in continuous culture on a defined medium under glucose limitation. In both organisms the enzymes of the glycolytic sequence up to the cleavage of hexosediphosphate were demonstrated, except that 6-phosphofructokinase activity in B. fibrisolvens was barely measurable. Instead, 1-phosphofructo-kinase was found in this organism. The role of this enzyme in glucose-grown cells is uncertain. Phosphopyruvate hydratase and pyruvate kinase could not be detected in R. albus extracts and their activities were extremely low in B. fibrisolvens, thus posing a problem as to pyruvate production in these organisms. At least part of the tricarboxylic acid cycle appeared to be functional in both organisms.Since several of the enzymes of this cycle in B. fibrisolvens were NADP-dependent, rather than NAD-dependent, and other workers have shown that fumarate reductase activity exceeds succinate dehydrogenase activity by more than 3:1, it is suggested that the tricarboxylic acid cycle may operate as a reductive cycle in this organism. Both organisms possessed fairly high activities of glutamate dehydrogenase and aspartate aminotransferase. The information obtained is inadequate to map out the pathways leading to the main end products of glucose fermentation.

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.

scholarly journals Triheptanoin partially restores levels of tricarboxylic acid cycle intermediates in the mouse pilocarpine model of epilepsy

2013 ◽  
Vol 129 (1) ◽  
pp. 107-119 ◽  
Author(s):  
Mussie G. Hadera ◽  
Olav B. Smeland ◽  
Tanya S. McDonald ◽  
Kah Ni Tan ◽  
Ursula Sonnewald ◽  
...  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Pilocarpine Model ◽  
Tricarboxylic Acid Cycle Intermediates
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