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1
Czosnowski, J. "Metabolism of excised embryos of Lupinus luteus L. VI. An electrophoretic analysis of some dehydrogenases in cultured embryos as compared with the normal seedling axes." Acta Societatis Botanicorum Poloniae 43, no. 1 (2015): 117–27. http://dx.doi.org/10.5586/asbp.1974.011.
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The electrophoretic patterns (disc electrophoresis) of the studied dehydrogenases: glucose-6-phosphate - (A), malate - (B), glutamate - (C), alcohol - (D) and lactate dehydrogenase (E), in the axial organs of isolated <i>Lupinus luteus</i> embryos and seedlings cultivated over 12 days are characterized by great similarities. With time, after the third day of cultivation the patterns begin to become less deyeloped. Analyses performed during the first 10 hours of imbibition of seed parts indicate that the maximal development of isozyme patterns occurs during the third hour after which the patterns become poorer. The most uniform type of pattern. and the lowest number of isozymes was shown by glutamate dehydrogenase, the richest pattern was shown by malate dehydrogenase. No band common for a 11 the 27 experimental elements was found.
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Thome, Trace, Zachary R. Salyers, Ravi A. Kumar, et al. "Uremic metabolites impair skeletal muscle mitochondrial energetics through disruption of the electron transport system and matrix dehydrogenase activity." American Journal of Physiology-Cell Physiology 317, no. 4 (2019): C701—C713. http://dx.doi.org/10.1152/ajpcell.00098.2019.
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Chronic kidney disease (CKD) leads to increased skeletal muscle fatigue, weakness, and atrophy. Previous work has implicated mitochondria within the skeletal muscle as a mediator of muscle dysfunction in CKD; however, the mechanisms underlying mitochondrial dysfunction in CKD are not entirely known. The purpose of this study was to define the impact of uremic metabolites on mitochondrial energetics. Skeletal muscle mitochondria were isolated from C57BL/6N mice and exposed to vehicle (DMSO) or varying concentrations of uremic metabolites: indoxyl sulfate, indole-3-acetic-acid, l-kynurenine, and kynurenic acid. A comprehensive mitochondrial phenotyping platform that included assessments of mitochondrial oxidative phosphorylation (OXPHOS) conductance and respiratory capacity, hydrogen peroxide production ( JH2O2), matrix dehydrogenase activity, electron transport system enzyme activity, and ATP synthase activity was employed. Uremic metabolite exposure resulted in a ~25–40% decrease in OXPHOS conductance across multiple substrate conditions ( P < 0.05, n = 5–6/condition), as well as decreased ADP-stimulated and uncoupled respiratory capacity. ATP synthase activity was not impacted by uremic metabolites; however, a screen of matrix dehydrogenases indicated that malate and glutamate dehydrogenases were impaired by some, but not all, uremic metabolites. Assessments of electron transport system enzymes indicated that uremic metabolites significantly impair complex III and IV. Uremic metabolites resulted in increased JH2O2 under glutamate/malate, pyruvate/malate, and succinate conditions across multiple levels of energy demand (all P < 0.05, n = 4/group). Disruption of mitochondrial OXPHOS was confirmed by decreased respiratory capacity and elevated superoxide production in cultured myotubes. These findings provide direct evidence that uremic metabolites negatively impact skeletal muscle mitochondrial energetics, resulting in decreased energy transfer, impaired complex III and IV enzyme activity, and elevated oxidant production.
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Lietz, T., K. Winiarska, and J. Bryła. "Ketone bodies activate gluconeogenesis in isolated rabbit renal cortical tubules incubated in the presence of amino acids and glycerol." Acta Biochimica Polonica 44, no. 2 (1997): 323–31. http://dx.doi.org/10.18388/abp.1997_4428.
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In isolated rabbit renal kidney-cortex tubules 2 mM glycerol, which is a poor gluconeogenic substrate, does not induce glucose formation in the presence of alanine, while it activates gluconeogenesis on substitution of alanine by aspartate, glutamate or proline. The addition of either 5 mM 3-hydroxybutyrate or 5 mM acetoacetate to renal tubules incubated with alanine + glycerol causes a marked induction of glucose production associated with inhibition of glutamine synthesis. In contrast, the rate of the latter process is not altered by ketones in the presence of glycerol and either aspartate, glutamine or proline despite the stimulation of glucose formation. Acceleration of gluconeogenesis by ketone bodies in the presence of amino acids and glycerol is probably due to (i) stimulation of pyruvate carboxylase activity, (ii) activation of malate-aspartate shuttle as concluded from elevated intracellular levels of malate, aspartate and glutamate, as well as (iii) diminished supply of ammonium for glutamine synthesis from alanine resulting from a decrease in glutamate dehydrogenase activity.
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Bryce, JH, and JT Wiskich. "Effect of NAD and Rotenone on the Partitioning of Malate Oxidation Between Malate Dehydrogenase and Malic Enzyme in Isolated Plant Mitochondria." Functional Plant Biology 12, no. 3 (1985): 229. http://dx.doi.org/10.1071/pp9850229.
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Our aim was to determine whether there is a specific link between NAD-malic enzyme and the rotenone- insensitive bypass of electron transport. Mitochondria were isolated from fresh beetroot tissue, aged beetroot slices, and turnips. Oxygen uptake and pyruvate production were measured in reactions where these mitochondria were metabolizing malate at pH 6.8 in the presence of glutamate, to facilitate the removal of oxaloacetate, and in its absence. In the absence of glutamate there was substantial activity of malic enzyme. NAD+ (577 �M) prevented a fall in oxygen uptake by stimulating malic enzyme. Rotenone (19 �M) reduced oxygen uptake. This inhibited rate was stimulated by NAD+ due, in particular, to a stimulation of malic enzyme. We conclude that the stimulation of malate metabolism by NAD+ is accounted for by malic enzyme due to the unfavourable equilibrium of malate dehydrogenase for malate oxidation and the resultant accumulation of oxaloacetate, and not to any specific link between malic enzyme and the rotenone-insensitive bypass. In the presence of glutamate, malate dehydrogenase was the predominant malate metabolizing enzyme. Oxygen uptake and malic enzyme were stimulated and inhibited by NAD+ and rotenone, respectively. In the presence of rotenone, NAD+ stimulated oxygen uptake and increased the percentage due to malic enzyme. This stimulation is accounted for by the higher Kin of the rotenone-insensitive dehydrogenase for NADH and the unfavourable equilibrium position of malate dehydrogenase resulting in activation of malic enzyme only. We conclude that malic enzyme is not specifically linked to the rotenone-insensitive pathway of electron transport. This has important implications for the regulation of energy metabolism in plants.
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Scaduto, R. C., and A. C. Schoolwerth. "Effect of bicarbonate on glutamine and glutamate metabolism by rat kidney cortex mitochondria." American Journal of Physiology-Renal Physiology 249, no. 4 (1985): F573—F581. http://dx.doi.org/10.1152/ajprenal.1985.249.4.f573.
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Isolated rat kidney cortex mitochondria were incubated at pH 7.4 in the presence or absence of a CO2/bicarbonate buffer (28 mM) to investigate the pH-independent role of bicarbonate on glutamine and glutamate metabolism. Changes in the concentration of key intermediates and products during the incubations were used to calculate metabolite flux rates through specific mitochondrial enzymes. With 1 mM glutamine and 2 mM glutamate as substrates, bicarbonate caused an inhibition of glutamate oxalacetate transaminase flux and a stimulation of glutamate deamination. The same effects were also produced with addition of either aminooxyacetate or malonate. These effects of bicarbonate were prevented when 0.2 mM malate was included as an additional substrate. Bicarbonate ion was identified as a potent competitive inhibitor of rat kidney cortex succinate dehydrogenase. These results indicate that aminooxyacetate, malonate, and bicarbonate all act to stimulate glutamate deamination through a suppression of glutamate transamination, and that the control by transamination of glutamate deamination is due to alterations in alpha-ketoglutarate metabolism. In contrast, in mitochondria incubated with glutamine in the absence of glutamate, bicarbonate was found to inhibit glutamate dehydrogenase flux. This effect was found to be due in part to the lower intramitochondrial pH observed in incubations with bicarbonate. These findings indicate that bicarbonate ion, independent of pH, may have an important regulatory role in renal glutamine and glutamate metabolism.
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Starritt, Emma C., Damien Angus, and Mark Hargreaves. "Effect of short-term training on mitochondrial ATP production rate in human skeletal muscle." Journal of Applied Physiology 86, no. 2 (1999): 450–54. http://dx.doi.org/10.1152/jappl.1999.86.2.450.
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Seven untrained volunteers [3 men, 4 women, 20.1 ± 2.0 (SD) yr, 66.0 ± 11.0 kg, 171 ± 13 cm] participated in a 10-day cycle exercise training program. Resting muscle samples were obtained from vastus lateralis before and after 5 and 10 days of training. Mitochondrial ATP production rate (MAPR) was assayed in isolated mitochondria by using a bioluminescence technique and referenced to the activity of glutamate dehydrogenase in the muscle sample. MAPR increased 136 and 161% after 10 days of training for the mitochondrial substrate combinations pyruvate + palmitoyl-l-carnitine + α-ketoglutarate + malate and palmitoyl-l-carnitine + malate, respectively. Total muscle glutamate dehydrogenase and citrate synthase activity increased 53 and 16%, respectively, after 5 days but did not significantly increase further after 10 days. The results from the present study indicate that MAPR, measured by using the substrate combinations pyruvate + palmitoyl-l-carnitine + α-ketoglutarate + malate and palmitoyl-l-carnitine + malate, can rapidly increase in response to endurance training.
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Mezhenska, O. A., V. A. Aleshin, T. Kaehne, A. V. Artiukhov, and V. I. Bunik. "Regulation of Malate Dehydrogenases and Glutamate Dehydrogenase of Mammalian Brain by Thiamine in vitro and in vivo." Biochemistry (Moscow) 85, no. 1 (2020): 27–39. http://dx.doi.org/10.1134/s0006297920010034.
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Katyare, S. S., C. S. Bangur, and J. L. Howland. "Is respiratory activity in the brain mitochondria responsive to thyroid hormone action?: a critical re-evaluation." Biochemical Journal 302, no. 3 (1994): 857–60. http://dx.doi.org/10.1042/bj3020857.
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The effects of in vivo treatment with graded doses (0.5-1.5 micrograms/g body weight) of thyroid hormones, tri-iodothyronine (T3) and thyroxine (T4), for 4 consecutive days to euthyroid rats on the respiratory activity of isolated brain mitochondria were examined. T4 stimulated coupled State-3 respiration with glutamate, pyruvate + malate, ascorbate + tetramethyl-p-phenylenediamine and succinate, in a dose-dependent manner; T3 was effective only at the highest (1.5 micrograms) dose employed. T4 was more effective than T3 in stimulating respiratory activity. State-4 respiratory rates were in general not influenced except in the case of the ascorbate + tetramethyl-p-phenylenediamine system. Primary dehydrogenase activities, i.e. glutamate dehydrogenase, malate dehydrogenase and succinate dehydrogenase, were stimulated about 2-fold; interestingly mitochondrial but not cytosolic malate dehydrogenase activity was influenced under these conditions. The hormone treatments did not greatly influence the mitochondrial cytochrome content. The results therefore suggest that thyroid hormone treatment not only stimulates primary dehydrogenase activities but may also directly influence the process of mitochondrial electron transfer.
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Artiukhov, Artem V., Anastasia V. Graf, Alexey V. Kazantsev, et al. "Increasing Inhibition of the Rat Brain 2-Oxoglutarate Dehydrogenase Decreases Glutathione Redox State, Elevating Anxiety and Perturbing Stress Adaptation." Pharmaceuticals 15, no. 2 (2022): 182. http://dx.doi.org/10.3390/ph15020182.
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Specific inhibitors of mitochondrial 2-oxoglutarate dehydrogenase (OGDH) are administered to animals to model the downregulation of the enzyme as observed in neurodegenerative diseases. Comparison of the effects of succinyl phosphonate (SP, 0.02 mmol/kg) and its uncharged precursor, triethyl succinyl phosphonate (TESP, 0.02 and 0.1 mmol/kg) reveals a biphasic response of the rat brain metabolism and physiology to increasing perturbation of OGDH function. At the low (TE)SP dose, glutamate, NAD+, and the activities of dehydrogenases of 2-oxoglutarate and malate increase, followed by their decreases at the high TESP dose. The complementary changes, i.e., an initial decrease followed by growth, are demonstrated by activities of pyruvate dehydrogenase and glutamine synthetase, and levels of oxidized glutathione and citrulline. While most of these indicators return to control levels at the high TESP dose, OGDH activity decreases and oxidized glutathione increases, compared to their control values. The first phase of metabolic perturbations does not cause significant physiological changes, but in the second phase, the ECG parameters and behavior reveal decreased adaptability and increased anxiety. Thus, lower levels of OGDH inhibition are compensated by the rearranged metabolic network, while the increased levels induce a metabolic switch to a lower redox state of the brain, associated with elevated stress of the animals.
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Hung, Hui-Chih, Meng-Wei Kuo, Gu-Gang Chang, and Guang-Yaw Liu. "Characterization of the functional role of allosteric site residue Asp102 in the regulatory mechanism of human mitochondrial NAD(P)+-dependent malate dehydrogenase (malic enzyme)." Biochemical Journal 392, no. 1 (2005): 39–45. http://dx.doi.org/10.1042/bj20050641.
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Human mitochondrial NAD(P)+-dependent malate dehydrogenase (decarboxylating) (malic enzyme) can be specifically and allosterically activated by fumarate. X-ray crystal structures have revealed conformational changes in the enzyme in the absence and in the presence of fumarate. Previous studies have indicated that fumarate is bound to the allosteric pocket via Arg67 and Arg91. Mutation of these residues almost abolishes the activating effect of fumarate. However, these amino acid residues are conserved in some enzymes that are not activated by fumarate, suggesting that there may be additional factors controlling the activation mechanism. In the present study, we tried to delineate the detailed molecular mechanism of activation of the enzyme by fumarate. Site-directed mutagenesis was used to replace Asp102, which is one of the charged amino acids in the fumarate binding pocket and is not conserved in other decarboxylating malate dehydrogenases. In order to explore the charge effect of this residue, Asp102 was replaced by alanine, glutamate or lysine. Our experimental data clearly indicate the importance of Asp102 for activation by fumarate. Mutation of Asp102 to Ala or Lys significantly attenuated the activating effect of fumarate on the enzyme. Kinetic parameters indicate that the effect of fumarate was mainly to decrease the Km values for malate, Mg2+ and NAD+, but it did not notably elevate kcat. The apparent substrate Km values were reduced by increasing concentrations of fumarate. Furthermore, the greatest effect of fumarate activation was apparent at low malate, Mg2+ or NAD+ concentrations. The Kact values were reduced with increasing concentrations of malate, Mg2+ and NAD+. The Asp102 mutants, however, are much less sensitive to regulation by fumarate. Mutation of Asp102 leads to the desensitization of the co-operative effect between fumarate and substrates of the enzyme.
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Gellerich, Frank Norbert, Zemfira Gizatullina, Sonata Trumbekaite, et al. "Cytosolic Ca2+ regulates the energization of isolated brain mitochondria by formation of pyruvate through the malate–aspartate shuttle." Biochemical Journal 443, no. 3 (2012): 747–55. http://dx.doi.org/10.1042/bj20110765.
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The glutamate-dependent respiration of isolated BM (brain mitochondria) is regulated by Ca2+cyt (cytosolic Ca2+) (S0.5=225±22 nM) through its effects on aralar. We now also demonstrate that the α-glycerophosphate-dependent respiration is controlled by Ca2+cyt (S0.5=60±10 nM). At higher Ca2+cyt (>600 nM), BM accumulate Ca2+ which enhances the rate of intramitochondrial dehydrogenases. The Ca2+-induced increments of state 3 respiration decrease with substrate in the order glutamate>α-oxoglutarate>isocitrate>α-glycerophosphate>pyruvate. Whereas the oxidation of pyruvate is only slightly influenced by Ca2+cyt, we show that the formation of pyruvate is tightly controlled by Ca2+cyt. Through its common substrate couple NADH/NAD+, the formation of pyruvate by LDH (lactate dehydrogenase) is linked to the MAS (malate–aspartate shuttle) with aralar as a central component. A rise in Ca2+cyt in a reconstituted system consisting of BM, cytosolic enzymes of MAS and LDH causes an up to 5-fold enhancement of OXPHOS (oxidative phosphorylation) rates that is due to an increased substrate supply, acting in a manner similar to a ‘gas pedal’. In contrast, Ca2+mit (intramitochondrial Ca2+) regulates the oxidation rates of substrates which are present within the mitochondrial matrix. We postulate that Ca2+cyt is a key factor in adjusting the mitochondrial energization to the requirements of intact neurons.
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Altube, H. A., F. Cabello, and J. M. Ortiz. "Caracterización de variedades y portainjertos de vid (Vitis vinifera L.) mediante isoenzimas de las raíces." AgriScientia 9, no. 2 (1992): 21–29. http://dx.doi.org/10.31047/1668.298x.v9.n2.2369.
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Twenty-one cultivars of Vitis vinifera L. and three rootstocks were chosen to study their biochemical characterization based on the electrophoretic separation of isoenzyme systems obtained from root tissue extracts. Acid phosphatases (ACPH), esterases (EST), catechol oxidases (CO), glutamate oxaloacetate transaminases (GOT), malate dehydrogenases (MDH), and peroxidases (PER) were separated using polyacrylamide gels and later stained with specific stains for the various isoenzyme systems. ACPH, CO, EST, and MDH were found to be the most adequate systems for characterization. The results of the study of the different systems and the grouping of the cultivars are presented. The use of isoenzymatic techniques for the characterization of Vitis genotypes is suggested.
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Dudina, Margarita A., Sergey A. Dogadin, and Аndrey A. Savchenko. "The negative effect of GH/IGF-1 excess on NAD- and NADP-dependent blood lymphocytes dehydrogenases activity in acromegaly." Problems of Endocrinology 62, no. 5 (2016): 59–60. http://dx.doi.org/10.14341/probl201662559-60.
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Background. Acromegaly is a rare serious condition characterized by chronic hypersecretion of growth hormone (GH) from a pituitary adenoma and induces the synthesis of insulin-like growth factor I (IGF-1). The idea of the crucial GH importance not only in the control of cell proliferation and differentiation, but, also, in the regulation of immune cells metabolism allows to think that chronic excess GH/IGF-I in acromegaly is the potent effector distortion of the immune response mechanisms. Aim. To study the NAD(P)-dependent dehydrogenases level in blood lymphocytes and their interaction with GH/IGF-1 concentration in patients with active acromegaly.Methods. The level of NAD(P)-dependent dehydrogenases in blood lymphocytes was studied in a group of 88 patients with active acromegaly, mean age 51.0±12.5 years. The NAD(P)-dependent dehydrogenases activity was determined by biochemiluminescence method. The concentrations of GH and IGF-1 were measured by ELISA.Results. Studying the activity of mitochondrial NAD(P)-dependent dehydrogenases found a decrease in all NAD-dependent oxidoreductase: NADIDH, NADGDH, and MDH (P<0.01), which allows to state the low level flow in the tricarboxylic acid cycle. In active acromegaly were revealed the decreasing activity of all studied oxidoreductases: glucose-6-phosphate dehydrogenase (P<0.01), NAD–lactate dehydrogenase (LDH) (P<0.001), NADH–LDH (P<0.001), NAD–malate dehydrogenase (MDH) (P<0.001), NADH–MDH (P<0.001), NADP–MDH (P<0.001), NAD–glutamate dehydrogenases (GDH) and NADH–GDH (P<0.001), NADP–GDH and NADPH–GDH (P<0.001), NAD–isocitrate dehydrogenases (IDH) and NADP–IDH (P<0.01 and P<0.001 respectively), and, also, glutathione reductase (P<0.001). Our data observed that decreasing activity of NADP–GDH positively correlated with the basal GH level (r=+0.23, P=0.04) and NADP–MDH activity with IGF-1 level (r=+0.30, P=0.008). The low NADH–MDH activity negatively correlated to the basal GH concentration (r=−0.23, P=0.04).Conclusion. The chronic excess of GH/IGF-1 causes a significant depletion of metabolic lymphocytes reserves and may play an important role in several systems malignancies of acromegaly patients. This pathway continues to attract interest as a potentially useful target for therapeutic design of acromegaly.
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Wipf, Daniel, Jean-Philippe Bedell, Bernard Botton, Jean Charles Munch, and François Buscot. "Polymorphism in morels: isozyme electrophoretic analysis." Canadian Journal of Microbiology 42, no. 8 (1996): 819–27. http://dx.doi.org/10.1139/m96-103.
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The aim of this study was to assess whether isozyme polymorphism in different members of the Morchellaceae could be used to improve the systematics in this fungal group and to characterize intraspecific crossings between monosporal strains in Morchella esculenta. For this purpose, isozyme electrophoretic analysis of the following enzymes was performed: glutamine synthetase, NAD–glutamate dehydrogenase, NADP–glutamate dehydrogenase, aspartate aminotransferase, malate dehydrogenase, NAD–glyceraldehyde phosphate dehydrogenase, glucose phosphate isomerase, and superoxide dismutase. The analyses allowed discrimination at the inter- or intra-specific levels and could help to establish a method of identification for strains in the Morchellaceae. To a certain extent they appeared to be suitable to analyze interactions of monosporal strains of Morchella esculenta in pairing experiments. The polymorphism shown in this study was consistent with the phylogenetic relationships between the investigated strains only at the genus level.Key words: isozyme analysis, electrophoresis, Morchella sp., polymorphism.
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Kennedy, Larry S., and Paul G. Thompson. "Identification of Sweetpotato Cultivars Using Isozyme Analysis." HortScience 26, no. 3 (1991): 300–302. http://dx.doi.org/10.21273/hortsci.26.3.300.
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The enzymes alcohol dehydrogenase, diaphorase, esterase, glutamate dehydrogenase, glucosephosphate isomerase, isocitrate dehydrogenase, malate dehydrogenase, malic enzyme, 6-phosphogluconate dehydrogenase, phosphoglucomutase, shikimate dehydrogenase, and xanthine dehydrogenase were analyzed by starch gel electrophoresis of leaf tissue from nine sweetpotato [Ipomoea batatas (L.) Lam.] cultivars. Bands of most enzymes were well-defined. Polymorphisms were found in nine enzymes, and cultivars were identified by comparing polymorphisms.
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Hassel, Bjørnar, and Anders Bråthe. "Cerebral Metabolism of Lactate in Vivo: Evidence for Neuronal Pyruvate Carboxylation." Journal of Cerebral Blood Flow & Metabolism 20, no. 2 (2000): 327–36. http://dx.doi.org/10.1097/00004647-200002000-00014.
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The cerebral metabolism of lactate was investigated. Awake mice received [3-13C]lactate or [1-13C]glucose intravenously, and brain and blood extracts were analyzed by 13C nuclear magnetic resonance spectroscopy. The cerebral up-take and metabolism of [3-13C]lactate was 50% that of [1-13C]glucose. [3-13C]Lactate was almost exclusively metabolized by neurons and hardly at all by glia, as revealed by the 13C labeling of glutamate, γ-aminobutyric acid and glutamine. Injection of [3-13C]lactate led to extensive formation of [2-13C]lactate, which was not seen with [1-13C]glucose, nor has it been seen in previous studies with [2-13C]acetate. This formation probably reflected reversible carboxylation of [3-13C]pyruvate to malate and equilibration with fumarate, because inhibition of succinate dehydrogenase with nitropropionic acid did not block it. Of the [3-13C]lactate that reached the brain, 20% underwent this reaction, which probably involved neuronal mitochondrial malic enzyme. The activities of mitochondrial malic enzyme, fumarase, and lactate dehydrogenase were high enough to account for the formation of [2-13C]lactate in neurons. Neuronal pyruvate carboxylation was confirmed by the higher specific activity of glutamate than of glutamine after intrastriatal injection of [1-14C]pyruvate into anesthetized mice. This procedure also demonstrated equilibration of malate, formed through pyruvate carboxylation, with fumarate. The demonstration of neuronal pyruvate carboxylation demands reconsideration of the metabolic interrelationship between neurons and glia.
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Chamberlin, M. E., H. C. Glemet, and J. S. Ballantyne. "Glutamine metabolism in a holostean (Amia calva) and teleost fish (Salvelinus namaycush)." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 260, no. 1 (1991): R159—R166. http://dx.doi.org/10.1152/ajpregu.1991.260.1.r159.
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Amino acid metabolism was examined in mitochondria from the lateral red muscle of a teleost (lake char, Salvelinus namaycush) and a nonteleost fish (bowfin, Amia calva). Isolated mitochondria oxidize a wide variety of substrates and have high respiratory control ratios. In both species, glutamine is oxidized more rapidly than any other amino acid. The rate of glutamine oxidation by bowfin mitochondria exceeds that of lake char mitochondria, and the bowfin displays correspondingly higher levels of mitochondrial phosphate-dependent glutaminase. It is suggested that amino acids in general, and glutamine in particular, are important oxidative substrates for nonteleost red muscle. The teleost red muscle, however, may rely on both glutamine and fatty acids as oxidative substrates. It appears that glutamate derived from glutamine is oxidized primarily via glutamate dehydrogenase, whereas exogenous glutamate is oxidized primarily via aspartate aminotransferase. Complete oxidation of glutamine may be accomplished in the absence of other substrates by conversion of glutamine-derived malate to pyruvate via malic enzyme. To assess the relative abilities of various tissues to synthesize and oxidize glutamine, the activities of glutamine synthetase and glutaminase were measured. The results of these studies indicate that the organization of glutamine metabolism of fish differs markedly from that in mammals.
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Ross, C. D., and D. A. Godfrey. "Distributions of aspartate aminotransferase and malate dehydrogenase activities in rat retinal layers." Journal of Histochemistry & Cytochemistry 33, no. 7 (1985): 624–30. http://dx.doi.org/10.1177/33.7.4008916.
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Aspartate aminotransferase (AAT), an enzyme interconverting glutamate and aspartate, has been suggested to be a marker for glutamatergic and/or aspartatergic neurons. However, AAT, glutamate, and aspartate are also involved in cellular metabolism, e.g., the malate-aspartate shuttle. To investigate the extent to which AAT might be involved in these several functions in retina, the distribution of AAT activity in rat retinal layers was compared to that of malate dehydrogenase (MDH), an enzyme of aerobic metabolism proposed to be physically complexed with AAT in the malate-aspartate shuttle mechanism. The distribution of AAT activity in retinal layers closely paralleled that of MDH (correlation coefficient AAT versus MDH = 0.93). AAT activity was proportionately higher than MDH in the photoreceptor inner segments, containing a high density of mitochondria, and in the outer plexiform layer (OPL), containing photoreceptor terminals and bipolar and horizontal cell processes. The amount of total AAT activity in the inner segments related to the mitochondrial isoenzyme is almost twice that in the other layers tested, including the OPL. The correlation between AAT and MDH activities is consistent with AAT involvement in retinal energy metabolism, although other functions, such as neurotransmission, are possible.
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Wakayama, Mamoru, Kazue Takashima, Yuko Tau, Sadatoshi Nakashima, Kenji Sakai, and Mitsuaki Moriguchi. "Spectrophotometric Assay ofd-Aspartate andd-Glutamate Usingd-Aspartate Oxidase with Malate Dehydrogenase and Glutamate Dehydrogenase." Analytical Biochemistry 250, no. 2 (1997): 252–53. http://dx.doi.org/10.1006/abio.1997.2230.
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Scholz, Thomas D., Stacia L. Koppenhafer, Cynthia J. Teneyck, and Brian C. Schutte. "Ontogeny of malate-aspartate shuttle capacity and gene expression in cardiac mitochondria." American Journal of Physiology-Cell Physiology 274, no. 3 (1998): C780—C788. http://dx.doi.org/10.1152/ajpcell.1998.274.3.c780.
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Developmental downregulation of the malate-aspartate shuttle has been observed in cardiac mitochondria. The goals of this study were to determine the time course of the postnatal decline and to identify potential regulatory sites by measuring steady-state myocardial mRNA and protein levels of the mitochondrial proteins involved in the shuttle. By use of isolated porcine cardiac mitochondria incubated with saturating concentrations of the cytosolic components of the malate-aspartate shuttle, shuttle capacity was found to decline by ∼50% during the first 5 wk of life (from 921 ± 48 to 531 ± 53 nmol ⋅ min−1 ⋅ mg protein−1). Mitochondrial aspartate aminotransferase mRNA levels were greater in adult than in newborn myocardium. mRNA levels of mitochondrial malate dehydrogenase in adult cardiac tissue were 224% of levels in newborn tissue, whereas protein levels were 54% greater in adult myocardium. Aspartate/glutamate carrier protein levels were also greater in adult than in newborn tissue. mRNA and protein levels of the oxoglutarate/malate carrier were increased in newborn myocardium. It was concluded that 1) myocardial malate-aspartate shuttle capacity declines rapidly after birth, 2) divergence of mitochondrial malate dehydrogenase mRNA and protein levels during development suggests posttranscriptional regulation of this protein, and 3) the developmental decline in malate-aspartate shuttle capacity is regulated by decreased oxoglutarate/malate carrier gene expression.
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Zhang, Xiao, Namrata Tomar, Sunil M. Kandel, Said H. Audi, Allen W. Cowley, and Ranjan K. Dash. "Substrate- and Calcium-Dependent Differential Regulation of Mitochondrial Oxidative Phosphorylation and Energy Production in the Heart and Kidney." Cells 11, no. 1 (2021): 131. http://dx.doi.org/10.3390/cells11010131.
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Mitochondrial dehydrogenases are differentially stimulated by Ca2+. Ca2+ has also diverse regulatory effects on mitochondrial transporters and other enzymes. However, the consequences of these regulatory effects on mitochondrial oxidative phosphorylation (OxPhos) and ATP production, and the dependencies of these consequences on respiratory substrates, have not been investigated between the kidney and heart despite the fact that kidney energy requirements are second only to those of the heart. Our objective was, therefore, to elucidate these relationships in isolated mitochondria from the kidney outer medulla (OM) and heart. ADP-induced mitochondrial respiration was measured at different CaCl2 concentrations in the presence of various respiratory substrates, including pyruvate + malate (PM), glutamate + malate (GM), alpha-ketoglutarate + malate (AM), palmitoyl-carnitine + malate (PCM), and succinate + rotenone (SUC + ROT). The results showed that, in both heart and OM mitochondria, and for most complex I substrates, Ca2+ effects are biphasic: small increases in Ca2+ concentration stimulated, while large increases inhibited mitochondrial respiration. Furthermore, significant differences in substrate- and Ca2+-dependent O2 utilization towards ATP production between heart and OM mitochondria were observed. With PM and PCM substrates, Ca2+ showed more prominent stimulatory effects in OM than in heart mitochondria, while with GM and AM substrates, Ca2+ had similar biphasic regulatory effects in both OM and heart mitochondria. In contrast, with complex II substrate SUC + ROT, only inhibitory effects on mitochondrial respiration was observed in both the heart and the OM. We conclude that the regulatory effects of Ca2+ on mitochondrial OxPhos and ATP synthesis are biphasic, substrate-dependent, and tissue-specific.
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Jalloh, Ibrahim, Adel Helmy, Duncan J. Howe, et al. "Focally perfused succinate potentiates brain metabolism in head injury patients." Journal of Cerebral Blood Flow & Metabolism 37, no. 7 (2016): 2626–38. http://dx.doi.org/10.1177/0271678x16672665.
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Following traumatic brain injury, complex cerebral energy perturbations occur. Correlating with unfavourable outcome, high brain extracellular lactate/pyruvate ratio suggests hypoxic metabolism and/or mitochondrial dysfunction. We investigated whether focal administration of succinate, a tricarboxylic acid cycle intermediate interacting directly with the mitochondrial electron transport chain, could improve cerebral metabolism. Microdialysis perfused disodium 2,3-13C2 succinate (12 mmol/L) for 24 h into nine sedated traumatic brain injury patients' brains, with simultaneous microdialysate collection for ISCUS analysis of energy metabolism biomarkers (nine patients) and nuclear magnetic resonance of 13C-labelled metabolites (six patients). Metabolites 2,3-13C2 malate and 2,3-13C2 glutamine indicated tricarboxylic acid cycle metabolism, and 2,3-13C2 lactate suggested tricarboxylic acid cycle spinout of pyruvate (by malic enzyme or phosphoenolpyruvate carboxykinase and pyruvate kinase), then lactate dehydrogenase-mediated conversion to lactate. Versus baseline, succinate perfusion significantly decreased lactate/pyruvate ratio (p = 0.015), mean difference −12%, due to increased pyruvate concentration (+17%); lactate changed little (−3%); concentrations decreased for glutamate (−43%) (p = 0.018) and glucose (−15%) (p = 0.038). Lower lactate/pyruvate ratio suggests better redox status: cytosolic NADH recycled to NAD+ by mitochondrial shuttles (malate-aspartate and/or glycerol 3-phosphate), diminishing lactate dehydrogenase-mediated pyruvate-to-lactate conversion, and lowering glutamate. Glucose decrease suggests improved utilisation. Direct tricarboxylic acid cycle supplementation with 2,3-13C2 succinate improved human traumatic brain injury brain chemistry, indicated by biomarkers and 13C-labelling patterns in metabolites.
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Camarasa, Carole, Jean-Philippe Grivet, and Sylvie Dequin. "Investigation by 13C-NMR and tricarboxylic acid (TCA) deletion mutant analysis of pathways for succinate formation in Saccharomyces cerevisiae during anaerobic fermentation." Microbiology 149, no. 9 (2003): 2669–78. http://dx.doi.org/10.1099/mic.0.26007-0.
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NMR isotopic filiation of 13C-labelled aspartate and glutamate was used to explore the tricarboxylic acid (TCA) pathway in Saccharomyces cerevisiae during anaerobic glucose fermentation. The assimilation of [3-13C]aspartate led to the formation of [2,3-13C]malate and [2,3-13C]succinate, with equal levels of 13C incorporation, whereas site-specific enrichment on C-2 and C-3 of succinate was detected only with [3-13C]glutamate. The non-random distribution of 13C labelling in malate and succinate demonstrates that the TCA pathway operates during yeast fermentation as both an oxidative and a reductive branch. The observed 13C distribution suggests that the succinate dehydrogenase (SDH) complex is not active during glucose fermentation. This hypothesis was tested by deleting the SDH1 gene encoding the flavoprotein subunit of the SDH complex. The growth, fermentation rate and metabolite profile of the sdh1 mutant were similar to those of the parental strain, demonstrating that SDH was indeed not active. Filiation experiments indicated the reductive branch of the TCA pathway was the main pathway for succinate production if aspartate was used as the nitrogen source, and that a surplus of succinate was produced by oxidative decarboxylation of 2-oxoglutarate if glutamate was the sole nitrogen source. Consistent with this finding, a kgd1 mutant displayed lower levels of succinate production on glutamate than on other nitrogen sources, and higher levels of oxoglutarate dehydrogenase activity were observed on glutamate. Thus, the reductive branch generating succinate via fumarate reductase operates independently of the nitrogen source. This pathway is the main source of succinate during fermentation, unless glutamate is the sole nitrogen source, in which case the oxidative decarboxylation of 2-oxoglutarate generates additional succinate.
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Savchenko, Andrey A., Alexander G. Borisov, and Ivan I. Gvozdev. "Features of the respiratory burst state of neutrophils and the activity of NAD(P)-dependent dehydrogenases in patients with widespread purulent peritonitis in the prognosis of the development of sepsis." Cytokines and inflammation 20, no. 1 (2023): 54–62. http://dx.doi.org/10.17816/ci2023231-8.
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Aim: Studying of the respiratory burst state and NAD(P)-dependent dehydrogenases activities in blood neutrophils features in the forecast of the development of abdominal sepsis in patients with widespread purulent peritonitis (WPP).
 Materials and methods. The study involved 50 patients with WPP in the preoperative period. Abdominal sepsis was developed by 35 patients (70.0%) from 5 to 10 days postoperative period, 15 patients (30.0%) hadn’t complications. The respiratory burst condition of blood neutrophils was examined using a chemiluminescent assay. Intracellular activity of the NAD- and NADP-dependent dehydrogenases was researched with using bioluminescent methods.
 Results. It was found that patients with WPP whose dynamics of the preoperative period will develop sepsis the chemiluminescent activity of blood neutrophils was characterized by a reduced level of spontaneous synthesis of the primary reactive oxygen species (ROS) and elevated levels of spontaneous synthesis of secondary ROS relative of the indicators identified in patients without subsequent complications. The feature of neutrophil metabolism in WPP patients without subsequent development of sepsis was high activity of the anaerobic lactate dehydrogenase reaction and decrease in activity of the NADP-dependent decarboxylating malate dehydrogenase. In patients with WPP and the subsequent development of sepsis was found high level of NAD-dependent substrates outflow citric acid cycle in the reaction of amino acid metabolism via glutamate dehydrogenase that may affect the activity of aerobic respiration in the neutrophils. Using correlation analysis was found that the intensity of the neutrophils respiratory burst in patients with no subsequent complications depends on the activity of anaerobic glycolysis.
 Conclusion. The established differences in the state of the respiratory burst and the activity of enzymes in neutrophils in patients with WPP, in depending on the subsequent development of the sepsis, determine the possibility of developing the method of forecasting complications and developing immunoactive therapy in the postoperative period of WPP.
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Lemieux, Guy, James Berkofsky, and Christiane Lemieux. "Renal tissue metabolism in the rat during chronic metabolic alkalosis: importance of glycolysis." Canadian Journal of Physiology and Pharmacology 64, no. 11 (1986): 1419–26. http://dx.doi.org/10.1139/y86-240.
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Chronic metabolic alkalosis was induced in rats drinking 0.3 M NaHCO3 and receiving 1 mg furosemide/100 g body weight per day intraperitoneally. Another group of animals received a potassium supplement in the form of 0.3 M KHCO3. In this group, hypokalemia did not develop and muscle potassium fell by only 18% versus 50% in those not receiving potassium. In vitro renal production of ammonia and uptake of glutamine fell by 40% with a decrease in the activity of glutaminase I and glutamate dehydrogenase. Activity of phosphofructokinase, a major enzyme of glycolysis, rose only in the kidney of animals receiving a potassium supplement. Fructose-1,6-diphosphatase fell as well as phosphoenolpyruvate carboxykinase. Malate dehydrogenase also fell. The activity of phosphofructokinase also rose in the liver, heart, and leg muscle. The major biochemical changes in the renal cortex were the following: glutamate, α-ketoglutarate, malate, lactate, pyruvate, alanine, aspartate, and citrate rose as well as calculated oxaloacetate. The concentration of intermediates like 2-phosphoglycerate, 3-phosphoglycerate, and glucose-6-phosphate fell. The cytosolic redox potential (NAD+/NADH) decreased. In addition to the fall in ammoniagenesis, it could be demonstrated in vitro that the renal tubules incubated with glutamine showed decreased glucose production and increased production of lactate and pyruvate. The concentration of lactate was elevated in all tissues examined including liver, heart, and leg muscle. This study confirms in the rat that decreased renal ammoniagenesis takes place following decreased uptake of glutamine in metabolic alkalosis. All other changes are accounted for by the process of increased glycolysis, which appears to take place in all tissues in metabolic alkalosis. All reported changes were more significant in animals receiving supplement of potassium, indicating that associated potassium deficiency plays a role in counteracting the observed changes now expected in metabolic alkalosis.
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Saniyam, Ibragimova, Elena Gukkengeimer, Nataliya Riger, Gulzat Kulbaeva, and Murat Gilmanov. "The New Wheat MDH-GOAT Enzyme Complex and its Application for Quantitative Determination of Glutamate Concentration." Advanced Materials Research 781-784 (September 2013): 957–60. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.957.
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The quantitative determination of glutamate is very important for diagnostic of many diseases of the nervous system, severity of stroke of the brain and also for determination glutamate in the food stuffs [1,2]. To the present days for quantitative determination of glutamate is wide used to the enzyme preparation of glutamate dehydrogenase (GDh) from bovine liver. However the application of GDh has the next serious disadvantages: high lability of this preparation and many substances strong change the activity of GDh. For example there are nucleotides, amino acid, steroid and metal ions. As the results the application of GDh preparation dont give reliable determination of quantity of glutamate. Thus there is the high necessity to propose another enzyme preparation for quantitative determination of glutamate without above mentioned disadvantages. In this reason we propose absolutely new enzyme preparation for this aim. In the laboratory of the enzyme structure and regulation of the Institute of the molecular biology and biochemistry of the Ministry of the education and science of the Republic of Kazakhstan was discovered the new enzyme complex (EC), which consists of malate dehydrogenase (MDh) and glutamate-oxaloacetate aminotransferase (GOAT) and used it for quantitative determination of glutamate concentration [3].
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Hage, Maha El, Justine Masson, Agnès Conjard-Duplany, Bernard Ferrier, Gabriel Baverel, and Guy Martin. "Brain Slices from Glutaminase-Deficient Mice Metabolize Less Glutamine: A Cellular Metabolomic Study with Carbon 13 NMR." Journal of Cerebral Blood Flow & Metabolism 32, no. 5 (2012): 816–24. http://dx.doi.org/10.1038/jcbfm.2012.22.
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In the brain, glutaminase is considered to have a key role in the provision of glutamate, a major excitatory neurotransmitter. Brain slices obtained from wild-type (control) and glutaminase-deficient (GLS1 +/–) mice were incubated without glucose and with 5 or 1 mmol/L [3-13C]glutamine as substrate. At the end of the incubation, substrate removal and product formation were measured by both enzymatic and carbon 13 nuclear magnetic resonance (13C-NMR) techniques. Slices from GLS1 +/– mice consumed less [3-13C]glutamine and accumulated less [3-13C]glutamate. They also produced less 13CO2 but accumulated amounts of 13C-aspartate and 13C-gamma-aminobutyric acid (GABA) that were similar to those found with brain slices from control mice. The newly formed glutamine observed in slices from control mice remained unchanged in slices from GLS1 +/– mice. As expected, flux through glutaminase in slices from GLS1 +/– mice was found diminished. Fluxes through all enzymes of the tricarboxylic acid cycle were also reduced in brain slices from GLS1 +/– mice except through malate dehydrogenase with 5 mmol/L [3-13C]glutamine. The latter diminutions are consistent with the decreases in the production of 13CO2 also observed in the slices from these mice. It is concluded that the genetic approach used in this study confirms the key role of glutaminase for the provision of glutamate.
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Winiarska, K., P. Bozko, T. Lietz, and J. Bryła. "Importance of glutamate dehydrogenase stimulation for glucose and glutamine synthesis in rabbit renal tubules incubated with various amino acids." Acta Biochimica Polonica 45, no. 3 (1998): 825–31. http://dx.doi.org/10.18388/abp.1998_4278.
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The effect of 2-aminobicyclo[2.2.1]heptan-2-carboxylic acid (BCH), an L-leucine nonmetabolizable analogue and an allosteric activator of glutamate dehydrogenase, on glucose and glutamine synthesis was studied in rabbit renal tubules incubated with alanine, aspartate or proline in the presence of glycerol and octanoate, i.e. under conditions of efficient glucose formation. With alanine+glycerol+octanoate the addition of BCH resulted in a stimulation of alanine and glycerol consumption, accompanied by an increased glucose, lactate and glutamine synthesis. In contrast, when alanine was substituted by either aspartate or proline, BCH altered neither glucose formation nor glutamine and glutamate synthesis, while an accelerated glycerol utilization was accompanied by a small increase in lactate production. In view of the BCH-induced changes in intracellular metabolite levels the acceleration of gluconeogenesis by BCH in the presence of alanine+glycerol+octanoate is probably due to (i) increased uptake of alanine via alanine aminotransferase, (ii) stimulation of phosphoenolpyruvate carboxykinase, a key-enzyme of gluconeogenesis, (iii) rise of glucose-6-phosphatase activity, as well as (iv) activation of the malate-aspartate shuttle resulting in an augmented glycerol utilization for lactate and glucose synthesis.
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Brand, K. "Glutamine and glucose metabolism during thymocyte proliferation. Pathways of glutamine and glutamate metabolism." Biochemical Journal 228, no. 2 (1985): 353–61. http://dx.doi.org/10.1042/bj2280353.
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Energy metabolism in proliferating cultured rat thymocytes was compared with that of freshly prepared non-proliferating resting cells. Cultured rat thymocytes enter a proliferative cycle after stimulation by concanavalin A and Lymphocult T (interleukin-2), with maximal rates of DNA synthesis at 60 h. Compared with incubated resting thymocytes, glucose metabolism by incubated proliferating thymocytes was 53-fold increased; 90% of the amount of glucose utilized was converted into lactate, whereas resting cells metabolized only 56% to lactate. However, the latter oxidized 27% of glucose to CO2, as opposed to 1.1% by the proliferating cells. Activities of hexokinase, 6-phosphofructokinase, pyruvate kinase and aldolase in proliferating thymocytes were increased 12-, 17-, 30- and 24-fold respectively, whereas the rate of pyruvate oxidation was enhanced only 3-fold. The relatively low capacity of pyruvate degradation in proliferating thymocytes might be the reason for almost complete conversion of glucose into lactate by these cells. Glutamine utilization by rat thymocytes was 8-fold increased during proliferation. The major end products of glutamine metabolism are glutamate, aspartate, CO2 and ammonia. A complete recovery of glutamine carbon and nitrogen in the products was obtained. The amount of glutamate formed by phosphate-dependent glutaminase which entered the citric acid cycle was enhanced 5-fold in the proliferating cells: 76% was converted into 2-oxoglutarate by aspartate aminotransferase, present in high activity, and the remaining 24% by glutamate dehydrogenase. With resting cells the same percentages were obtained (75 and 25). Maximal activities of glutaminase, glutamate dehydrogenase and aspartate aminotransferase were increased 3-, 12- and 6-fold respectively in proliferating cells; 32% of the glutamate metabolized in the citric acid cycle was recovered in CO2 and 61% in aspartate. In resting cells this proportion was 41% and 59% and in mitogen-stimulated cells 39% and 65% respectively. Addition of glucose (4 mM) or malate (2 mM) strongly decreased the rates of glutamine utilization and glutamate conversion into 2-oxoglutarate by proliferating thymocytes and also affected the pathways of further glutamate metabolism. Addition of 2 mM-pyruvate did not alter the rate of glutamine utilization by proliferating thymocytes, but decreased the rate of metabolism beyond the stage of glutamate significantly. Formation of acetyl-CoA in the presence of pyruvate might explain the relatively enhanced oxidation of glutamate to CO2 (56%) by proliferating thymocytes.
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Kimmich, George A., James A. Roussie, and Joan Randles. "Aspartate aminotransferase isotope exchange reactions: implications for glutamate/glutamine shuttle hypothesis." American Journal of Physiology-Cell Physiology 282, no. 6 (2002): C1404—C1413. http://dx.doi.org/10.1152/ajpcell.00487.2001.
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Aspartate aminotransferase (AAT) catalyzes amino group transfer from glutamate (Glu) or aspartate (Asp) to a keto acid acceptor—oxaloacetate (OA) or α-ketoglutarate (KG), respectively. Data presented here show that AAT catalyzes two partial reactions resulting in isotope exchange between3H-labeled Glu or 3H-labeled Asp and the cognate keto acid in the absence of the keto acid acceptor required for the net reaction. Tritiated keto acid product was detected by release of 3H2O from C-3 during base-induced enolization. Tritium released directly from C-2 (or C-3) by the enzyme was also evaluated and is a small fraction of that released because of exchange to the keto acid pool. Exchange is dependent on AAT concentration, time-dependent, proportional to the amino-to-keto acid ratio, and blocked by aminooxyacetate (AOA), an AAT inhibitor. Enzymatic conversion of [3H]KG to Glu by glutamic dehydrogenase (GDH) or of [3H]OA to malate by malic dehydrogenase (MDH) “protects” the label from release by base, showing that base-induced isotope release is from keto acid rather than a result of release during the exchange process. AAT isotope exchange is discussed in the context of the glutamate/glutamine shuttle hypothesis for astrocyte/neuron carbon cycling.
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Grossman, A., R. N. Rosenberg, and L. Warmoth. "Glutamate and malate dehydrogenase activities in Joseph disease and olivopontocerebellar atrophy." Neurology 37, no. 1 (1987): 106. http://dx.doi.org/10.1212/wnl.37.1.106.
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Panov, Alexander V., Vladimir I. Mayorov, Anna E. Dikalova, and Sergey I. Dikalov. "Long-Chain and Medium-Chain Fatty Acids in Energy Metabolism of Murine Kidney Mitochondria." International Journal of Molecular Sciences 24, no. 1 (2022): 379. http://dx.doi.org/10.3390/ijms24010379.
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Scientists have long established that fatty acids are the primary substrates for kidney mitochondria. However, to date we still do not know how long-chain and middle-chain fatty acids are oxidized at the mitochondrial level. Our previous research has shown that mitochondria from the heart, brain, and kidney oxidize palmitoylcarnitine at a high rate only in the presence of succinate, glutamate, or pyruvate. In this paper, we report properties of the isolated kidney mitochondria and how malate and succinate affect the oxidation of C16 and C8 acylcarnitines. The isolated kidney mitochondria contain very few endogenous substrates and require malate to oxidize pyruvate, glutamate, and C16 or C8 acylcarnitines. We discovered that with 10 µM of C16 or C8 acylcarnitines, low concentrations of malate (0.2 mM) or succinate (0.5 mM) enhance the States 4 and 3 respiratory rates several times. The highest respiration rates were observed with C16 or C8 acylcarnitines and 5 mM succinate mixtures. Results show that kidney mitochondria, unlike the heart and brain mitochondria, lack the intrinsic inhibition of succinate dehydrogenase. Additionally, results show that the oxidation of fatty acid by the small respirasome’s supercomplex generates a high level of CoQH2, and this makes SDH in the presence of succinate reverse the flow of electrons from CoQH2 to reduce fumarate to succinate. Finally, we report evidence that succinate dehydrogenase is a key mitochondrial enzyme that allows fast oxidation of fatty acids and turns the TCA cycle function from the catabolic to the anabolic and anaplerotic metabolic pathways.
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Holten, Eirik. "IMMUNOLOGICAL COMPARISON OF NADP-DEPENDENT GLUTAMATE DEHYDROGENASE AND MALATE DEHYDROGENASE IN GENUS NEISSERIA." Acta Pathologica Microbiologica Scandinavica Section B Microbiology and Immunology 82B, no. 6 (2009): 849–59. http://dx.doi.org/10.1111/j.1699-0463.1974.tb02383.x.
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Byrne, David H., and Thomas G. Littleton. "Electrophoretic Characterization of Diploid Plums of the Southeastern United States." Journal of the American Society for Horticultural Science 113, no. 6 (1988): 918–24. http://dx.doi.org/10.21273/jashs.113.6.918.
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Abstract Twenty-nine Japanese-type plum clones were assayed for isozymic variability for eight enzyme systems. Glutamate dehydrogenase (GDH), leucine amino-peptidase (LAP), malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), and peroxidase (PX) showed variability among the plums surveyed. 6-phosphogluconate dehydrogenase (6PGD) and triosephosphate isomerase (TPI) were not variable. Isozymic characterization uniquely identified 38% of the clones. The remainder separated into groups of two to three clones that were distinguishable using vegetative morphological characteristics. Reported parentage of five out of nine plums examined was not consistent with their isozymic genotypes.
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Alvarez, B., and G. Martínez-Drets. "Metabolic characterization of Acetobacter diazotrophicus." Canadian Journal of Microbiology 41, no. 10 (1995): 918–24. http://dx.doi.org/10.1139/m95-126.
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Carbon and nitrogen metabolism were investigated in Acetobacter diazotrophicus Pal 3, a N2-fixing bacterium able to grow at low pH and at high sugar concentration. Enzymatic, respiratory, and uptake studies were performed. The main active pathway for the catabolism of phosphorylated glucose was the pentose phosphate pathway. In addition, A. diazotrophicus directly oxidized glucose, gluconate, and ketogluconates through respiratory chain-linked enzymes. Soluble enzymes for the oxidation of glucose and gluconate were also found. Acetobacter diazotrophicus had a complete tricarboxylic acid cycle with a respiratory chain-linked malate dehydrogenase. The ability to grow on two- and three-carbon substrates would be explained by the presence of gluconeogenesis. Lack of bacterial growth on dicarboxylates was explained by the absence of a transport system. Ammonium assimilation proceeded mainly through glutamate dehydrogenase under ammonium excess but also through energy-demanding glutamine synthetase and glutamate synthase under N2-fixing conditions. Acetobacter diazotrophicus was not able to transport sucrose and its ability to grow on this disaccharide was explained by the presence of an extracellular enzyme with saccharolytic activity.Key words: Acetobacter diazotrophicus, carbon–nitrogen metabolism, extracellular saccharolytic activity, sucrose–succinate uptake.
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Vikman, Per-Åke. "The symbiotic vesicle is a major site for respiration in Frankia from Alnus incana root nodules." Canadian Journal of Microbiology 38, no. 8 (1992): 779–84. http://dx.doi.org/10.1139/m92-127.
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A technique was developed for preparation of Frankia symbiotic vesicles, free of hyphae. The symbiotic vesicles were isolated by isopycnic centrifugation of disrupted Frankia vesicle clusters prepared from root nodules of Alnus incana (L.) Moench. Activities in symbiotic vesicles were compared with activities in intact symbiotic vesicle clusters on a total protein basis. Respiratory capacity was tested with 6-phosphogluconate, malate + glutamate, and NADH as added substrates. With all three substrates, specific respiration was doubled after symbiotic vesicle isolation. Nitrogenase was used as a symbiotic vesicle specific marker and its specific activity increased similarly to respiration. Activities of four respiratory enzymes were assayed on crude cell-free extracts obtained after sonication of symbiotic vesicle preparations. According to the increased specific rates after symbiotic vesicle isolation, NAD+:6-phosphogluconate dehydrogenase (EC 1.1.1.44) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) were mainly localized in symbiotic vesicles. NAD+:malate dehydrogenase (EC 1.1.1.37) and glutamate-oxaloacetate transaminase (EC 2.6.1.1) were also present in symbiotic vesicles, but their specific activities were not increased compared with the symbiotic vesicle clusters. The magnitude of increased activities suggested that the symbiotic vesicle is a major site for hexose respiration in symbiotic Frankia. An apparent Km for O2 between 20 and 30 μM indicated that symbiotic vesicles in symbiotic vesicle clusters have a restricted oxygen diffusion rate. Key words: Frankia, symbiotic vesicles, respiration, nitrogenase, oxygen diffusion.
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Kubik-Dobosz, Genowefa, and Grażyna Kłobus. "The localization of nitrite reductase, glutamate synthase and malate metabolism enzymes in Pisum arvense L. roots." Acta Societatis Botanicorum Poloniae 54, no. 1 (2014): 85–93. http://dx.doi.org/10.5586/asbp.1985.008.
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Centrifugation of a homogenate made from <em>Pisum arvense</em> L. roots in a sucrose density gradient enabled the separation of the plastid fraction from mitochondria and microsomes. The presence of nitrite reductase and glutamate synthase was demonstrated in the plastids. Malic enzyme activity was not linked with any organelle fraction and was found only in the cytosol. High malate dehydrogenase activity was found in the mitochondria fraction, although its activity was also determined in plastids. The results suggest that malic acid metabolism in plastids may be the source of reduced pyridine nucleotides for reactions catalysed by nitrite reductase and glutamate synthase.
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Panov, A. V., and R. C. Scaduto. "Substrate specific effects of calcium on metabolism of rat heart mitochondria." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 4 (1996): H1398—H1406. http://dx.doi.org/10.1152/ajpheart.1996.270.4.h1398.
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Oxidative metabolism in the heart is tightly coupled to mechanical work. Because this coupling process is believed to involve Ca2+, the roles of mitochondrial Ca2+ in the regulation of oxidative phosphorylation was studied in isolated rat heart mitochondria. The electrical component of the mitochondrial membrane potential (delta psi) and the redox state of the pyridine nucleotides were determined during the oxidation of various substrates under different metabolic states. In the absence of added adenine nucleotides, the NADP+ redox couple was almost completely reduced, regardless of the specific substrate and the presence of Ca2+, whereas NAD+ couple redox state was highly dependent on the substrate type and the presence of Ca2+. Titration of respiration with ADP, in the presence of excess hexokinase and glucose, showed that both respiration and NAD(P)+ reduction were very sensitive to ADP. The maximal enzyme reaction rate of ADP-stimulated respiration Michaelis constants (Km) for ADP were dependent on the particular substrate employed. delta psi was much less sensitive to ADP. With either alpha-ketoglutarate or glutamate as substrate, Ca2+ significantly increased reduction of NAD(P)+.Ca2+ did not influence NAD(P)+ reduction with either acetylcarnitine or pyruvate as substrate. In the presence of ADP, delta psi was increased by Ca2+ at all metabolic states with glutamate plus malate, 0.5 mM alpha-ketoglutarate plus malate, or pyruvate plus malate as substrates. The data presented support the hypothesis that cardiac respiration is controlled by the availability of both Ca2+ and ADP to mitochondria. The data indicate that an increase in substrate supply to mitochondria can increase mitochondrial respiration at given level of ADP. This effect can be produced by Ca2+ with substrates such as glutamate, which utilize alpha-ketoglutarate dehydrogenase activity for oxidation. Increases in respiration by Ca2+ may mitigate an increase in ADP during periods of increased cardiac work.
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Bizeau, Michael E., Wayne T. Willis, and Jeffrey R. Hazel. "Differential responses to endurance training in subsarcolemmal and intermyofibrillar mitochondria." Journal of Applied Physiology 85, no. 4 (1998): 1279–84. http://dx.doi.org/10.1152/jappl.1998.85.4.1279.
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To examine the effect of endurance training (6 wk of treadmill running) on regional mitochondrial adaptations within skeletal muscle, subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria were isolated from trained and control rat hindlimb muscles. Mitochondrial oxygen consumption (V˙o 2) was measured polarographically by using the following substrates: 1 mM pyruvate + 1 mM malate (P+M), 10 mM 2-oxoglutarate, 45 μM palmitoyl-dl-carnitine + 1 mM malate, and 10 mM glutamate. Spectrophotometric assays of cytochrome- c reductase and NAD-specific isocitrate dehydrogenase (IDH) activity were also performed. Maximal (state III) and resting (state IV)V˙o 2 were lower in SS than in IMF mitochondria in both trained and control groups. In SS mitochondria, training elicited significant 36 and 20% increases in state III V˙o 2 with P+M and glutamate, respectively. In IMF mitochondria, training resulted in a smaller (20%), yet significant, increase in state IIIV˙o 2 with P+M as a substrate, whereas state IIIV˙o 2 increased 33 and 27% with 2-oxoglutarate and palmitoyl-dl-carnitine + malate, respectively. Within groups, cytochrome- c reductase and IDH activities were lower in SS when compared with IMF mitochondria. Training increased succinate-cytochrome- c reductase in both SS (30%) and IMF mitochondria (28%). IDH activity increased 32% in the trained IMF but remained unchanged in SS mitochondria. We conclude that endurance training promotes substantial changes in protein stoichiometry and composition of both SS and IMF mitochondria.
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Jiang, Yonghua, Yingwei Qi, Xilong Chen, et al. "Combined Metabolome and Transcriptome Analyses Unveil the Molecular Mechanisms of Fruit Acidity Variation in Litchi (Litchi chinensis Sonn.)." International Journal of Molecular Sciences 24, no. 3 (2023): 1871. http://dx.doi.org/10.3390/ijms24031871.
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Fruit acidity determines the organoleptic quality and nutritive value of most fruits. In litchi, although the organic acid composition of pulps is known, the molecular mechanisms and genes underlying variation in fruit acidity remain elusive. Herein, developing pulps of two contrasting litchi varieties, Huaizhi (HZ, low-acidity) and Boye_No.8 (B8, high-acidity), were subjected to metabolomics and transcriptomics, and the dynamic metabolome and transcriptional changes were determined. Measurements revealed that the dominant acidity-related organic acid in litchi pulps is malate, followed in low levels by citrate and tartrate. Variation in litchi pulps’ acidity is mainly associated with significant differences in malate and citrate metabolisms during fruit development. Malic acid content decreased by 91.43% and 72.28% during fruit ripening in HZ and B8, respectively. The content of citric acid increased significantly in B8, while in HZ it was reduced considerably. Differentially accumulated metabolites and differentially expressed genes analyses unveiled fumarate, succinate, 2-oxoglutarate, GABA (γ-aminobutyric acid), phosphoenolpyruvate, and citrate metabolisms as the key driving pathways of litchi fruits’ acidity variation. The drastic malate and citrate degradation in HZ was linked to higher induction of fumarate and GABA biosynthesis, respectively. Thirty candidate genes, including three key genes (LITCHI026501.m2, fumarase; LITCHI020148.m5, glutamate decarboxylase; and LITCHI003343.m3, glutamate dehydrogenase), were identified for functional studies toward genetic modulation of litchi fruit acidity. Our findings provide insights into the molecular basis of acidity variation in litchi and provide valuable resources for fruit quality improvement.
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Angelov, Georgi B., and Teodora A. Ivanova. "Isoenzyme variation and genetic affinities among four species of the genus Festuca L. (Poaceae)." Biodiversity: Research and Conservation 28, no. 1 (2012): 3–8. http://dx.doi.org/10.2478/v10119-012-0021-6.
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Abstract Festuca L. is one of the most complicated genera in Poaceae. Polyacrylamide gel electrophoresis was used to study the isoenzyme variation of glutamate-oxaloacetate transaminase, malate dehydrogenase, glutamate dehydrogenase, isocitrate dehydrogenase and 6-phosphogluconate dehydrogenase in natural populations of F. valesiaca Schleich. ex Gaud., F. rupicola Heuff., F. dalmatica (Hack.) K. Richt. and F. stojanovii (Acht.) Kozuharov ex Foggi & Petrova. The aim of the present study was to assess isoenzyme variation and genetic affinities among the four species of the genus Festuca. Genetic identities (I) and distances (D) were calculated to evaluate qualitative genetic affinities and systematic relationships among the species. Considering the patterns of isoenzyme variation in the studied group, it is evident that F. dalmatica and F. stojanovii are closely related species. The species F. valesiaca and F. rupicola are isoenzymatically well characterized as distinct genetic entities. The obtained results generally support recent narrow species concept in the genus Festuca.
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Aleshin, Vasily A., Anastasia V. Graf, Artem V. Artiukhov, et al. "Pentylenetetrazole-Induced Seizures Are Increased after Kindling, Exhibiting Vitamin-Responsive Correlations to the Post-Seizures Behavior, Amino Acids Metabolism and Key Metabolic Regulators in the Rat Brain." International Journal of Molecular Sciences 24, no. 15 (2023): 12405. http://dx.doi.org/10.3390/ijms241512405.
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Epilepsy is characterized by recurrent seizures due to a perturbed balance between glutamate and GABA neurotransmission. Our goal is to reveal the molecular mechanisms of the changes upon repeated challenges of this balance, suggesting knowledge-based neuroprotection. To address this goal, a set of metabolic indicators in the post-seizure rat brain cortex is compared before and after pharmacological kindling with pentylenetetrazole (PTZ). Vitamins B1 and B6 supporting energy and neurotransmitter metabolism are studied as neuroprotectors. PTZ kindling increases the seizure severity (1.3 fold, p < 0.01), elevating post-seizure rearings (1.5 fold, p = 0.03) and steps out of the walls (2 fold, p = 0.01). In the kindled vs. non-kindled rats, the post-seizure p53 level is increased 1.3 fold (p = 0.03), reciprocating a 1.4-fold (p = 0.02) decrease in the activity of 2-oxoglutarate dehydrogenase complex (OGDHC) controlling the glutamate degradation. Further, decreased expression of deacylases SIRT3 (1.4 fold, p = 0.01) and SIRT5 (1.5 fold, p = 0.01) reciprocates increased acetylation of 15 kDa proteins 1.5 fold (p < 0.01). Finally, the kindling abrogates the stress response to multiple saline injections in the control animals, manifested in the increased activities of the pyruvate dehydrogenase complex, malic enzyme, glutamine synthetase and decreased malate dehydrogenase activity. Post-seizure animals demonstrate correlations of p53 expression to the levels of glutamate (r = 0.79, p = 0.05). The correlations of the seizure severity and duration to the levels of GABA (r = 0.59, p = 0.05) and glutamate dehydrogenase activity (r = 0.58, p = 0.02), respectively, are substituted by the correlation of the seizure latency with the OGDHC activity (r = 0.69, p < 0.01) after the vitamins administration, testifying to the vitamins-dependent impact of the kindling on glutamate/GABA metabolism. The vitamins also abrogate the correlations of behavioral parameters with seizure duration (r 0.53–0.59, p < 0.03). Thus, increased seizures and modified post-seizure behavior in rats after PTZ kindling are associated with multiple changes in the vitamin-dependent brain metabolism of amino acids, linked to key metabolic regulators: p53, OGDHC, SIRT3 and SIRT5.
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FRICKE, W., and E. PAHLICH. "Malate: A Possible Source of Error in the NAD Glutamate Dehydrogenase Assay." Journal of Experimental Botany 43, no. 11 (1992): 1515–18. http://dx.doi.org/10.1093/jxb/43.11.1515.
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Pedersen, Henrik, Morten Carlsen, and Jens Nielsen. "Identification of Enzymes and Quantification of Metabolic Fluxes in the Wild Type and in a Recombinant Aspergillus oryzae Strain." Applied and Environmental Microbiology 65, no. 1 (1999): 11–19. http://dx.doi.org/10.1128/aem.65.1.11-19.1999.
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ABSTRACT Two α-amylase-producing strains of Aspergillus oryzae, a wild-type strain and a recombinant containing additional copies of the α-amylase gene, were characterized with respect to enzyme activities, localization of enzymes to the mitochondria or cytosol, macromolecular composition, and metabolic fluxes through the central metabolism during glucose-limited chemostat cultivations. Citrate synthase and isocitrate dehydrogenase (NAD) activities were found only in the mitochondria, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase (NADP) activities were found only in the cytosol, and isocitrate dehydrogenase (NADP), glutamate oxaloacetate transaminase, malate dehydrogenase, and glutamate dehydrogenase (NAD) activities were found in both the mitochondria and the cytosol. The measured biomass components and ash could account for 95% (wt/wt) of the biomass. The protein and RNA contents increased linearly with increasing specific growth rate, but the carbohydrate and chitin contents decreased. A metabolic model consisting of 69 fluxes and 59 intracellular metabolites was used to calculate the metabolic fluxes through the central metabolism at several specific growth rates, with ammonia or nitrate as the nitrogen source. The flux through the pentose phosphate pathway increased with increasing specific growth rate. The fluxes through the pentose phosphate pathway were 15 to 26% higher for the recombinant strain than for the wild-type strain.
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Vasileva, Ivanina, Juliana Ivanova, and Liliana Gigova. "Selection of nitrogen source affects the growth and metabolic enzyme activities of Chlorella vulgaris (Beijerinck) strain R-06/2 (chlorophyta)." Archives of Biological Sciences 72, no. 2 (2020): 291–300. http://dx.doi.org/10.2298/abs200219023v.
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The choice of nitrogen source in a cultivation medium can specifically affect the physiology and biochemistry of microalgae. To increase the production of low-cost valuable biomass, the preferred nitrogen form for each alga should be determined. The aim of our study was to analyze the effects of different nitrogen sources and cultivation times on the growth, biochemical composition and the activities of glutamine synthetase, glutamate synthase, glutamate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and proteases of Chlorella vulgaris R-06/2. Media supplemented with urea or ammonium nitrate provided similarly (p>0.05) high growth rates for a short cultivation time (4 days). The two nitrogen compounds applied simultaneously ensured better biomass yield but for prolonged cultivation. In the exponential growth phase, ammonium nitrate stimulated (p<0.05) protein production, whereas urea enhanced (p<0.05) the carbohydrate content in older cultures as compared to the other nitrogen sources. The activity of each of the studied metabolic enzymes of C. vulgaris R-06/2 varied specifically depending on the nitrogen source and the growth phase, ensuring the maintenance of efficient, balanced metabolism under all cultivation conditions. When using large-scale cultivation to produce biomass for various useful applications, the selection of nitrogen source should be based on algal metabolism.
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Guimarães Filho, Artur, Rodrigo Maranguape Silva da Cunha, Paulo Roberto Leitão de Vasconcelos, and Sergio Botelho Guimarães. "Glutamine and ornithine alpha-ketoglutarate supplementation on malate dehydrogenases expression in hepatectomized rats." Acta Cirurgica Brasileira 29, no. 6 (2014): 365–70. http://dx.doi.org/10.1590/s0102-86502014000600003.
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Vasconcelos, Paulo Roberto Cavalcante de, Claudio Duarte da Costa Neto, Raquel Cavalcante de Vasconcelos, Pedro Paulo Chaves de Souza, Paulo Roberto Leitão Vasconcelos, and Sérgio Botelho Guimarães. "Effect of glutamine on the mRNA level of key enzymes of malate-aspartate shuttle in the rat intestine subjected to ischemia reperfusion." Acta Cirurgica Brasileira 26, suppl 1 (2011): 26–31. http://dx.doi.org/10.1590/s0102-86502011000700006.
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PURPOSE: To determine the effects of oral L-glutamine (L-Gln) and the dipeptide l-alanyl-glutamine (L-Ala-Gln) upon the activity of the malate-aspartate shuttle in the rat distal small intestine following ischemia and reperfusion. METHODS: Seventy-two Wistar rats (350-400g), were randomized in 2 groups (n = 36): group S (Sham) and Group T (Treatment) and divided into 12 subgroups (n = 6): A-A6, and B1-B6. The subgroups A1-A3 were subjected to sham procedures at 30 and 60 minutes. Thirty minutes before the study, rats were treated with calcium caseinate, 0.5g/Kg (subgroups A1, A4, B1, B4), L-Gln, 0.5g / kg (subgroups A2, A5, B2 and B5) or L-Ala-Gln, 0.75g/Kg (subgroups A3, A6, B3, B6), administered by gavage. Ischemia was achieved by clamping the mesenteric vessels, delimiting a segment of bowel 5 cm long and 5 cm apart from the ileocecal valve. Samples were collected 30 and 60 minutes after start of the study for real-time PCR assay of malate dehydrogenases (MDH1-2) and aspartate-aminotransferases (GOT1-2) enzymes. RESULTS: Tissue MDH and GOT mRNA expression in intestinal samples from rats preconditioned with either L-Gln or L-Ala-Gln showed no significant differences both during ischemia and early reperfusion. CONCLUSION: Activation of the malate-aspartate shuttle system appears not to be the mechanism of glutamine-mediated elevation of glucose oxidation in rat intestine during ischemia/reperfusion injury.
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PICARD, B., and Ph GOULLET. "Comparative Electrophoretic Profiles of Esterases, and of Glutamate, Lactate and Malate Dehydrogenases, from Aeromonas hydrophila, A. caviae and A. sobria." Microbiology 131, no. 12 (1985): 3385–91. http://dx.doi.org/10.1099/00221287-131-12-3385.
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Goullet, Ph, and B. Picard. "Characterization of Enterobacter cloacae and E. sakazakii by Electrophoretic Polymorphism of Acid Phosphatase, Esterases, and Glutamate, Lactate and Malate Dehydrogenases." Microbiology 132, no. 11 (1986): 3105–12. http://dx.doi.org/10.1099/00221287-132-11-3105.
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Green, Laura S., Youzhong Li, David W. Emerich, Fraser J. Bergersen та David A. Day. "Catabolism of α-Ketoglutarate by a sucA Mutant of Bradyrhizobium japonicum: Evidence for an Alternative Tricarboxylic Acid Cycle". Journal of Bacteriology 182, № 10 (2000): 2838–44. http://dx.doi.org/10.1128/jb.182.10.2838-2844.2000.
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ABSTRACT A complete tricarboxylic acid (TCA) cycle is generally considered necessary for energy production from the dicarboxylic acid substrates malate, succinate, and fumarate. However, a Bradyrhizobium japonicum sucA mutant that is missing α-ketoglutarate dehydrogenase is able to grow on malate as its sole source of carbon. This mutant also fixes nitrogen in symbiosis with soybean, where dicarboxylic acids are its principal carbon substrate. Using a flow chamber system to make direct measurements of oxygen consumption and ammonium excretion, we confirmed that bacteroids formed by thesucA mutant displayed wild-type rates of respiration and nitrogen fixation. Despite the absence of α-ketoglutarate dehydrogenase activity, whole cells of the mutant were able to decarboxylate α-[U-14C]ketoglutarate and [U-14C]glutamate at rates similar to those of wild-typeB. japonicum, indicating that there was an alternative route for α-ketoglutarate catabolism. Because cell extracts fromB. japonicum decarboxylated [U-14C]glutamate very slowly, the γ-aminobutyrate shunt is unlikely to be the pathway responsible for α-ketoglutarate catabolism in the mutant. In contrast, cell extracts from both the wild type and mutant showed a coenzyme A (CoA)-independent α-ketoglutarate decarboxylation activity. This activity was independent of pyridine nucleotides and was stimulated by thiamine PPi. Thin-layer chromatography showed that the product of α-ketoglutarate decarboxylation was succinic semialdehyde. The CoA-independent α-ketoglutarate decarboxylase, along with succinate semialdehyde dehydrogenase, may form an alternative pathway for α-ketoglutarate catabolism, and this pathway may enhance TCA cycle function during symbiotic nitrogen fixation.