Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.1 (aspartate aminotransferase)
 21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In experiments on 6 sheep the authors found the following enzyme activities in bacteria in the rumen fluid, bacteria adhering to the epithelium of the rumen wall and bacteria adhering to food particles in the rumen (given in nkat X g-1 bacterial dry weight): GDH (NADH): 725 +/- 165, 558 +/- 127, 661 +/- 153; GDH (NADPH): 558 +/- 338, 255 +/- 88, 565 +/- 139; GOAT (NADH): 46 +/- 23, 67 +/- 31, 66 +/- 14; GOGAT/NADPH: 58 +/- 27, 56 +/- 15, 65 +/- 29; GS: 153 +/- 65, 69 +/- 35, 71 +/- 32; ALT: 71 +/- 25, 43 +/- 20, 52 +/- 11; AST: 52 +/- 12, 33 +/- 16, 28 +/- 15. The results show that, except for GDH (NADPH), there were no significant differences between the given enzyme activities in the rumen fluid and in bacteria adhering to the rumen wall and to food. Adherent rumen bacteria have the same potential possibilities as the rumen fluid bacteria for the utilization of ammonia, particularly for the synthesis of glutamic acid, glutamine, alanine and aspartic acid, with the above enzymes as catalysts. By means of the GS/GOGAT system, adherent rumen bacteria can probably synthesize glutamic acid in the presence of a limited NH3 concentration in the rumen.
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PMID:Ammonia-utilizing enzymes of adherent bacteria in the sheep's rumen. 286 70

Amino acids of the glutamate family, viz. glutamic acid, aspartic acid, glutamine, gamma-amino-butyric acid (GABA) and alanine, along with the activities of glutamic acid dehydrogenase (GDH), aspartic acid aminotransferase (AST), alanine aminotransferase (ALT), glutamine synthetase (GS), glutaminase, glutamic acid decarboxylase (GAD) and GABA-aminotransferase (GABA-T) were estimated in cerebral cortex, cerebellum and brain stem of rats treated with a single dose of lithium or with seven daily doses of lithium (3 m-equiv./kg body wt). The levels of GABA were found to increase in cerebral cortex and brain stem following the administration of a single dose and also were found to be increased in cerebral cortex and cerebellum after treatment for 7 days. The content of glutamic acid was increased in all three brain regions after treatment for 7 days. Glutamine was increased in both cerebral cortex and brain stem after treatment for 7 days, whereas aspartic acid was increased in brain stem after both the administration of single dose and treatment for 7 days. A significant increase (P less than 0.05) in the activity of GS was observed in brain stem after 7 days of treatment. Similarly, a significant increase (P less than 0.01) in the activity of AST was observed in all three regions of the brain following the treatment for 7 days. The above results are discussed in relation to the known effects of lithium on brain cation metabolism and a suggestion is made that an imbalance in the functional activities of glutamic acid and GABA as a result of quantitative changes in these amino acids, brought about by lithium, may play a role in the therapeutic efficacy of lithium in bipolar disorders.
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PMID:Acute and short-term effects of lithium on glutamate metabolism in rat brain. 286 24

The amino acid pool sizes of Trichomonas vaginalis are reported. Alanine, glutamic acid, proline and leucine account for 72% of the measured amino acids. Growth of T. vaginalis was unaffected by gostatin, an irreversible inhibitor of aspartate aminotransferase, when the enzyme activity within the cell had been completely inhibited and a specific elevation of the aspartate pool had occurred. In media lacking aspartate and glutamate, the amino acid substrates of the aspartate aminotransferase reaction, gostatin caused a larger increase in the aspartate pool. During incubation of cells with or without gostatin, aspartate and glutamate were produced in the medium, presumably by proteolysis of medium proteins. Hence any requirement for the aspartate aminotransferase reaction might have been bypassed. Glutamate-gamma-hydroxamate and aminooxyacetate inhibited growth of T. vaginalis but caused large changes in the pool-sizes of aspartate, glutamate, pyruvate plus oxaloacetate and 2-oxoglutarate, suggesting a more general interference with amino acid metabolism.
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PMID:Modulation of amino acid and 2-oxo acid pools in Trichomonas vaginalis by aspartate aminotransferase inhibitors. 287 95

We measured neurotransmitter markers in autopsied brain of infants with glycine encephalopathy (GE). Because patients with GE develop intractable seizures, special attention was devoted to those neurotransmitter systems implicated in human epilepsy. Mean levels of glycine in the frontal cortex of GE patients were three times higher than control values. No abnormalities were observed for concentrations of gamma-aminobutyric acid (and related receptors), other major neurotransmitter amino compounds, or activities of cholineacetyltransferase and aspartate aminotransferase. Mean acetylcholinesterase activity was significantly elevated by 46%. As experimental data suggest, glycine markedly potentiates the action of the excitatory neurotransmitter glutamic acid. To the extent that the brain seizures in patients with GE can be explained by this mechanism, pharmacotherapy with excitatory amino acid antagonists may represent a new approach to the treatment of GE.
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PMID:Brain neurotransmitters in glycine encephalopathy. 290 30

Twelve serum analytes [triglycerides, cholesterol, total and conjugated bilirubin, high-density-lipoprotein cholesterol (HDL-C), alkaline phosphatase (AP), gammaglutamyl transferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), beta-glucuronidase (beta-glu), alanine aminopeptidase (AAP), and 5'-nucleotidase (5'nuc)] were measured to investigate their correlation with exposure to polychlorinated biphenyls (PCBs) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT). The relationship between serum lipids, lipophilic toxicants, and the analytes was also evaluated. The beta-glu, 5'nuc, triglycerides, cholesterol, and total bilirubin correlated positively and significantly with log concentrations of serum total PCBs and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), a metabolite of DDT. The more highly chlorinated PCBs (Aroclor 1260) had significant, positive correlations with several serum analytes, but the less chlorinated PCBs (Aroclor 1242) correlated significantly and negatively only with HDL-cholesterol. Triglyceride- and cholesterol-rich lipoproteins were added to serum to determine the effects of lipids on these assays. Several were spuriously elevated. AP and beta-glu were not affected by lipoprotein addition with the methods used in this study. AAP was increased significantly only at triglyceride concentrations exceeding 400 mg/dl. Lipoproteins may be elevated because of deranged lipid metabolism in response to PCBs, or PCBs may be elevated because elevated lipoproteins are present, as in familial triglyceridemia, a relatively common dyslipoproteinemia. Because this relationship is not well understood with respect to cause and effect, we propose the further use in epidemiological investigations of assay methods that are little affected by blood lipids yet are correlated with PCB concentrations. Congener-specific quantification of PCBs would help elucidate the effects of PCBs on assays used to monitor health effects.
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PMID:Effects of polychlorinated biphenyls and lipemia on serum analytes. 302 64

The fate of aspartic acid used for proline fermentation by Kurthia catenaforma was traced by using aspartic acid-U-(14)C. The radioactivities of proline and glutamic acid increased with the disappearance of aspartic acid. After 40 hr, aspartic acid disappeared from the medium and radioactive alpha-ketoglutaric acid was detected. The radioactivity of proline reached 44% of aspartic acid radioactivity at 40 hr. The specific radioactivities of these amino acids and of alpha-ketoglutaric acid supported the notion that proline is produced mainly from aspartic acid via alpha-ketoglutaric acid and glutamic acid. Since the levels of glutamic acid dehydrogenases (EC 1.4.1.2 and EC 1.4.1.4) were low in this organism, it appears that the nitrogen atom of aspartic acid enters proline by the action of aspartate aminotransferase (EC 2.6.1.1). The mechanism of proline production is discussed on the basis of the role of aspartic acid in this fermentation.
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PMID:Mechanism of proline production by Kurthia catenaforma. 501 17

1. N-(5'-Phosphopyridoxyl)-l-glutamic acid (P-Pxy-Glu, compound I) is readily converted at pH3 into a substance (P-Pxy-Glp, compound II) characterized as N-(5'-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid. 2. The u.v., i.r. and fluorescence spectra of P-Pxy-Glu and P-Pxy-Glp have been determined; from the u.v. spectra their pK values have been found and compared. 3. The apoenzyme of aspartate aminotransferase is rapidly and irreversibly inactivated by P-Pxy-Glu, but is inactivated more slowly by P-Pxy-Glp. The complex with P-Pxy-Glp is stable enough to be isolated, but it is slowly reactivated in the presence of excess of pyridoxal phosphate. 4. The u.v. spectrum of the complex of apoenzyme and P-Pxy-Glp suggests that it contains a hydrogen bond between the phenolic hydroxyl group and the pyrrolidone nitrogen; this specifies the conformation of most of the molecule of P-Pxy-Glp. This conformation is similar to that previously postulated for the enzyme-glutamate complex except for the side chain of glutamate. Hence both the affinity of P-Pxy-Glp for the apoenzyme and the fact that it is more easily removed than P-Pxy-Glu are explicable.
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PMID:N-(5'-phosphopyridoxyl)glutamic acid and N-(5'-phosphopyridoxyl)-2-oxopyrrolidine-5-carboxylic acid and their action on the apoenzyme of aspartate aminotransferase. 512 78

A two-stage surgical occlusion of the portal vein was employed to produce hyperammonaemia in the rat. The procedure resulted in a significant rise of arterial blood ammonia level from 70 . 5 +/- 6 . 5 mumol/l (mean +/- SEM, n = 10) to 214 . 0 +/- 37 . 7 mumol/l and in a rise of venous blood ammonia from 65 . 0 +/- 9 . 4 mumol/l to 122 . 2 +/- 7 . 4 mumol/l during the first day following the complete vein occlusion. A marked increase of the arteriovenous difference of ammonia concentration from virtually zero in sham-operated controls to 72 +/- 9 (n = 8) mumol/l in rats 1 day after the surgical manipulation suggested uptake of ammonia by skeletal muscle. Rat muscle glutamine synthetase activity increased from 0 . 46 +/- 0 . 06 u/mg (n = 7) in controls to 2 . 7 +/- 0 . 3 u/mg (n = 7) on the fourth day following portal vein ligation, and muscle branched chain amino acids aminotransferase increased from 0 . 2 +/- 0 . 05 u/mg in controls to 0 . 96 +/- 0 . 1 u/mg (n = 7) during the first day of ligation. Glutamine dehydrogenase and aspartate aminotransferase activities were not affected by the surgical procedure. These observations suggest that ammonia trapping in skeletal muscle is coupled to glutamine formation via amination of glutamic acid. This conclusion was further supported by the finding that ammonia uptake correlated (r = 0 . 92) with enhanced release of glutamine from muscle and that treatment with methionine sulfoximine, a potent inhibitor of glutamine synthetase, changed the arteriovenous difference of glutamine from -0 . 92 +/- 0 . 01 mmol/l in ligated animals (net release) to +0 . 12 +/- 0 . 01 mmol/l (net uptake) in ligated and inhibitor-treated animals. Similarly, the inhibitor also abolished the arterio-venous difference of ammonia. Thus, the animal model of hyperammonaemia and the muscle enzyme assays reveal that skeletal muscle is involved in the regulation of blood ammonia level by conversion of ammonia, via glutamic acid, to glutamine.
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PMID:Ammonia uptake by skeletal muscle in the hyperammonaemic rat. 612 77

Metabolism of the glutamate group of amino acids--glutamic acid, gamma-amino-butyric acid, glutamine, aspartic acid and alanine--was studied in the brain of rat as a function of age. The levels of glutamic acid, glutamine and aspartic acid decreased while those of gamma-aminobutyric acid, and alanine increased with age. The results on the activity of the twelve enzymes involved in the metabolism showed that five of them (glutamate dehydrogenase, glutamine synthase, gamma-aminobutyric acid transaminase, succinic semialdehyde dehydrogenase and NAD+-isocitrate dehydrogenase) decreased, while four of them (glutaminase, glutamotransferase, glutamic acid decarboxylase, and alpha-ketoglutarate dehydrogenase) increased. The other three enzymes (aspartate aminotransferase, alanine aminotransferase and NADP+-isocitrate dehydrogenase) did not show any significant change in activity. An age-related increase was seen in alpha-ketoglutarate and ammonia, the intermediates involved in the metabolism of these amino acids. The changes in the level of these amino acids are discussed in relation to the altered energy metabolism during aging.
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PMID:Metabolism of the glutamate group of amino acids in rat brain as a function of age. 614 62

The activity of certain key enzymes involved in glutamic acid metabolism was studied in purified brain mitochondria and in mitochondrial subfractions separated in a discontinuous 1.2--1.6 mol/l sucrose gradient. Alanine aminotransferase and glutamate dehydrogenase were found to be matrix enzymes and aspartate aminotransferase to be associated with the inner mitochondrial membranes. After the purified mitochondria had been separated into 5 subfractions, aspartate aminotransferase and NAD+-dependent isocitrate dehydrogenase were found to be bound to the lighter mitochondrial subfractions settling at the 1.4--1.5 mol/l sucrose boundary while alanine aminotransferase, 4-aminobutyrate transaminase and glutamate dehydrogenase were associated with the heavier subfractions settling below 2.4 mol/l sucrose. The highest specific activity of the given enzymes was found in the subfraction settling at the 1.4--1.5 mol/l sucrose boundary, the only exception being alanine aminotransferase activity, whose maximum was found in the subfractions settling in 1.5 and 1.6 mol/l sucrose. It was concluded that alanine aminotransferase, in conjunction with glutamate dehydrogenase, is linked to NH3 binding and to the oxidation of reduced adenine nucleotides; in addition, alanine aminotransferase is presumed to have the function of transporting glutamate from the mitochondria to the extramitochondrial space.
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PMID:Alanine aminotransferase and some other enzymes in different populations of free brain cortex mitochondria. 645 52


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