Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dynamics of the glutamine synthetase and glutamate dehydrogenase activity was studied during cultivation of Str. antibioticus on media with different contents of glucose and ammonium sulfate. No correlation between the enzymes activity and the levels of oleandomycin production by the mycelium was observed. It was shown that the levels of oleandomycin biosynthesis repression by glucose did not depend on ammonium sulfate concentration in the medium.
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PMID:[Nitrogen metabolism of Streptomyces antibioticus on media with various glucose contents]. 305 1

The metabolic pathways of glucose were studied by histochemical reactions in some species of gastropods living in different habitats. The glycolytic pathway is histochemically indicated by positive results for glucose-6-phosphate isomerase, fructose-1,6-biphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, and D-lactate dehydrogenase. The enzymes of the Krebs cycle gave different responses: isocitrate dehydrogenase and L-malate dehydrogenase were positive, whilst succinate dehydrogenase was constantly negative. Malate synthetase activity was also demonstrated. Despite L-glutamate dehydrogenase is undetectable, the presence of transaminase indicates the gluconeogenetic route. Phosphoglucomutase and glucose-6-phosphate phosphatase appear also positive. The metabolic meaning of our results were discussed.
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PMID:Histochemical research on metabolic pathways of glucose in some species of Mollusca Gastropoda. 311 Nov 50

The literature concerning the metabolism of carbon and nitrogen compounds in ectomycorrhizal associations of trees is reviewed. The absorption and translocation of mineral ions by the mycelia require an energy source and a reductant which are both supplied by respiratory catabolism of carbohydrates produced by the host plant. Photosynthates are also required to generate the carbon skeletons for amino acid and carbohydrate syntheses during the growth of the mycelia. Competition for photosynthates occurs between the fungal cells and the various vegetative sinks in the host tree. The nature of carbon compounds involved in these processes, their routes of metabolism, the mechanisms of control and the partitioning of metabolites between the various sites of utilization are only poorly understood. Both ascomycetous and basidiomycetous ectomycorrhizal fungi synthesize and some, if not all, accumulate mannitol, trehalose and triglycerides. The fungal strains employ the Embden--Meyerhof pathway of glucose catabolism and the key enzymes of the pentose phosphate pathway (6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, transaldolase and transketolase). Anaplerotic CO2 fixation, via pyruvate carboxylase and/or phosphoenolpyruvate carboxykinase, provides high pools of amino acids. This process could be important in the recapture and assimilation of respired CO2 in the rhizosphere. The ectomycorrhizas are thought to contain the Embden--Meyerhof pathway, the pentose phosphate pathway and the tricarboxylic acid cycle, which provide the carbon skeletons for the assimilation of ammonia into amino acids. The main route of assimilation of ammonia appears to be through the glutamine synthetase-glutamate synthase cycle in the ectomycorrhizas. Glutamate dehydrogenase plays a minor role in this process. Glutamate dehydrogenase and glutamine synthetase are present in free-living ectomycorrhizal fungi and they participate in the assimilation of ammonia and the synthesis of amino acids through the glutamate dehydrogenase/glutamine synthetase sequence. In both in vitro cultures of fungi and ectomycorrhizas, the assimilated nitrogen accumulates in glutamine. Glutamine, but also ammonia, are thought to be exported from the fungal tissues to the host cells. Studies on the metabolism of ectomycorrhizas and ectomycorrhizal fungi have focused on the metabolic pathways and compounds which accumulate in the symbiotic tissues. Studies on regulation of the overall process, and the control of enzyme activity in particular, are still fragmentary.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Carbon and nitrogen metabolism in ectomycorrhizal fungi and ectomycorrhizas. 312 Jul 92

The effect of hypoxia and post-hypoxic recovery were studied in gastrocnemius muscle of young-adult and mature beagle dogs. Furthermore, the possible interference of pharmacological treatment with nicergoline was evaluated in these conditions. Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose 6-phosphate, pyruvate, lactate), Kreb's cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate) and related free amino acids (glutamate, alanine), ammonium ion, energy store and mediators (ATP, ADP, AMP and creatine phosphate), and the energy charge potential were evaluated. Furthermore, in the crude extract and/or mitochondrial fraction of another portion of the same gastrocnemius muscle the maximum rate (Vmax) of some muscular enzymes related to the anaerobic glycolytic pathway (hexokinase, lactate dehydrogenase), the Kreb's cycle (citrate synthase, malate dehydrogenase), the aminoacid pool related to the Krebs' cycle (glutamate dehydrogenase and aspartate aminotransferase), the electron transfer chain (cytochrome oxidase) and NAD+/NADH exchanges (total NADH cytochrome c reductase) was evaluated. Some glycolytic metabolites and Krebs' cycle intermediates were modified by acute hypoxia, while free amino acids and energy mediators remained practically unchanged. The pharmacological treatment maintained the glucose and succinate muscular concentrations within the normal range, during hypoxia. The behaviour of muscular metabolites during hypoxia and/or post-hypoxic recovery is an age-related event. In fact, only in young-adult animals did the altered values return to normal in post-hypoxic recovery. In the present experimental conditions, only minor changes were observed as far as muscular enzyme activities are concerned. In any case, some enzyme activities tested showed different Vmax in young-adult dogs in comparison with mature ones.
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PMID:Effect of hypoxia, aging and pharmacological treatment on muscular metabolites and enzyme activities. 322 9

The effect of ammonia on the alanine metabolism was investigated in perfused rat liver. Gluconeogenesis was found to be stimulated by physiological concentrations of ammonia, while being inhibited at higher concentrations (5-10 mM). The stimulating effect of 0.5 mM ammonia was studied in greater detail. In addition to glucose formation seen enhanced five times, increased rates were observed for ureogenesis as well as the formation of lactate and pyruvate, demonstrating also activation of the total alanine turnover. Furthermore, the mitochondrial and cytosolic NAD systems were increasingly oxidized as reflected by the beta-hydroxybutyrate/acetoacetate and lactate/pyruvate ratios. The shift of the beta-hydroxybutyrate/acetoacetate ratio was correlated to the ATP demand by gluconeogenesis and ureogenesis. The elevated concentration of pyruvate was found to have caused stimulation of gluconeogenesis since there existed a Michaelis-Menten type relation between pyruvate concentration and glucose formation irrespective of the presence or absence of ammonia. The flux through glutamate dehydrogenase was calculated from the total alanine turnover and urea formation, and noted to be diminished in the presence of ammonia despite the increased alanine turnover. It is concluded that glutamate dehydrogenase, at least in part, controls the total alanine turnover in the absence of ammonia.
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PMID:Stimulation of alanine metabolism in rat liver by ammonia. 325 56

The integrated use of several energy sources allows high muscular power outputs to be sustained. Muscle glycogen provides the major fuel source for muscular exercise, but other fuels can provide alternative energy sources which allow for muscle glycogen-sparing and an increased potential for prolonged high metabolic rates. Blood-borne glucose, derived from liver glycogenolysis and glyconeogenesis, as well as intra-muscular lipids and plasma free fatty acids derived from adipose tissue provide the main energy alternatives to muscle glycogen. Several amino acids, including the essential amino acid leucine, are also used directly as oxidizable fuels during exercise. Depending on the duration and intensity of exercise and other factors such as glycogen stores and energy intake, amino acids can provide from a few to approximately 10% of the total energy for sustained exercise. Additionally, many amino acids can be converted to glutamate (via glutamate dehydrogenase) and then to alanine (via glutamate-pyruvate transaminase). Alanine, along with lactate and pyruvate, are recognized as the major gluconeogenic precursors. Via this mechanism, several amino acids play crucial roles in providing the carbon sources for maintaining blood glucose homeostasis during exercise and glycogen restitution during recovery. And finally, during exercise and recovery, amino acids likely play important anaplerotic functions sustaining the whole metabolic apparatus.
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PMID:Amino acid and protein metabolism during exercise and recovery. 331 14

Measurement of the arteriovenous differences for free amino acids across rat kidney reveals that glycine and citrulline are removed and serine and arginine are added to the circulation. In addition, glutamine is taken up in large quantities by kidneys of animals that need to excrete large quantities of acid (e.g., diabetic animals, NH4Cl-fed animals, and animals fed a high protein diet). Glutamine is the major precursor of urinary ammonia and thus renal glutamine metabolism plays a key role in acid-base homeostasis. This process occurs primarily in the cells of the convoluted proximal tubule. Glutamine carbon is converted to glucose in acidotic rats and is totally oxidized in dogs. Regulation of glutamine metabolism occurs at two levels: acute regulation and chronic regulation. Acute regulation is, in part, mediated through a fall in intracellular [H+]. This activates alpha-ketoglutarate dehydrogenase and, ultimately, glutaminase. Chronic regulation involves induction of key enzymes, including, in the rat, glutaminase, glutamate dehydrogenase, and phosphoenolpyruvate carboxykinase. During the acidosis of prolonged starvation, the kidneys' requirement for glutamine must be met from muscle proteolysis and thus becomes a drain on lean body mass. Serine synthesis occurs by two separate pathways: from glycine by the combined actions of the glycine cleavage enzyme and serine hydroxymethyltransferase and from gluconeogenic precursors using the phosphorylated-intermediate pathway. Both pathways are located in the cells of the proximal tubule. Conversion of glycine to serine is ammoniagenic and the activity of the glycine cleavage enzyme is increased in acidosis. The function of serine synthesis by the phosphorylated-intermediate pathway is not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The 1986 Borden award lecture. The role of the kidney in amino acid metabolism and nutrition. 332 68

The net production of citrate from exogenous substrates by rat ventral prostate was investigated. The preparation of isolated prostate epithelial cells was described. These cells were capable of oxidizing pyruvate (5 mmol/l) as a source of acetyl coenzyme A. The addition of aspartate + alpha-ketoglutarate (5 mmol/l) in the presence of pyruvate resulted in significant net production of citrate and excess oxalacetate. In the presence of aspartate and glutamate, the cells were capable of producing citrate without excessive oxalacetate production. Neither glucose alone nor glucose plus pyruvate resulted in net citrate production. The results demonstrated that aspartate could serve as a 4-carbon source of oxalacetate for citrate synthesis. Furthermore, the results indicate the intramitochondrial operation of a glutamate-aspartate-citrate pathway involving mitochondrial aspartate aminotransferase and glutamic dehydrogenase activities in prostate epithelial cells.
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PMID:Net citrate production by isolated prostate epithelial cells. 337 41

In vitro resting, short-term mitogen stimulated, and proliferating rat thymocytes as well as established human T and B lymphoblastoid cell lines were compared in their capacity to metabolize glucose and glutamine as energy source. Furthermore, the pathways of glutamine metabolism in these cells were studied. Compared with resting thymocytes, glucose metabolism of proliferating thymocytes was 36-fold increased during the incubation; 92% of the amount of glucose utilized was converted into trioses mainly lactate, whereas resting cells metabolized only 38% to trioses. However, the latter oxidized 19% of glucose to CO2, as opposed to 1.1% by the proliferating cells. Rates of glucose uptake and degradation to products by the malignant T lymphoblastoid cell line (Jurkat) were nearly identical with those observed with proliferating rat thymocytes, whereas the benign B lymphoblastoid cell lines (DHg-B-1 and LV-B-1) showed significantly higher rates of glucose metabolism. All three transformed lymphoblastoid cell lines, however, metabolized glucose almost completely to lactate as did the proliferating rat thymocytes. Lymphocytes are able to utilize glutamine with glutamate, aspartate and ammonia being the major end-products. A complete recovery of glutamine carbon in the products was obtained with all cells. Glutamine utilization by incubated proliferating rat thymocytes was 8-fold increased as compared to the resting cells. Again the human T lymphoblastoid cell line showed the same rates of glutamine uptake and conversion into products as did the proliferating rat thymocytes, whereas both B lymphoblastoid cell lines had about 2.5-fold enhanced rates as compared to the T cell line. The results indicate that during lymphocyte proliferation caused by mitogen stimulation as well as by permanent transformation into lymphoblastoid cell lines glucose metabolism is altered not only quantitatively but also qualitatively by changing from partly aerobic to almost complete anaerobic glucose breakdown. Glutamine has been found to be a suitable energy source for lymphocytes. About 75% of the amount of glutamate derived from glutamine entered into the citric acid cycle via the aspartate aminotransferase, and the remaining 25% via the glutamate dehydrogenase reaction. The changes in metabolic rates observed in proliferating as well as in transformed or leukemic lymphocytes appear to be reliable parameters to characterize the state of lymphocyte activation or to evaluate the efficacy of lymphokines.
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PMID:Metabolic alterations associated with proliferation of mitogen-activated lymphocytes and of lymphoblastoid cell lines: evaluation of glucose and glutamine metabolism. 349 37

Peptides representing the C-terminal end of secretin were synthetized and their effects tested along with secretin on column-perifused isolated mouse pancreatic islets. Insulin release induced by 10 mmol/l D-glucose was potentiated by secretin tested in a concentration range of 0.01-10 micrograms/ml; the maximal effect was obtained with 1 microgram/ml secretin. This effect was mimicked by 50-500 micrograms/ml NH2-Leu-Leu-Gln-Gly-Leu-Val-NH2, [S-(22-27)], which represents an amidated C-terminal sequence of the secretin molecule. The consecutive smaller secretin C-terminal peptides had either no effects [Val-NH2, S-(24-27)] or only marginally [S-(26-27), S-(23-27)] potentiating effects on insulin release in the presence of 10 mmol/l D-glucose. The effects of secretin and S-(22-27) were not influenced by 2 mmol/l glutamine. The intact hormone and the five synthetic peptides as well as Val-NH2 had no stimulatory effect on islet glutamate dehydrogenase activity. In fact, S-(23-27), S-(24-27), and S-(25-27) inhibited the islet glutamate dehydrogenase activity, the activation by which amino acids and amino acid derivatives are known to elicit a potentiation of insulin release. Our results suggest that the C-terminal part is important to the marked potentiation of glucose-induced insulin release in vitro by secretin.
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PMID:Secretin and its C-terminal hexapeptide potentiates insulin release in mouse islets. 351 6


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