Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The changes in both the levels of some free amino acids and their metabolism in the rat brain during the first 24 hr of postnatal life were studied. The content of glutamic acid decreased for the first 2 hr; it remained at the lowest level for the next 4 hr, when it began to increase. The content of alanine decreased for the first 6 hr and approached the adult level. Oxygen consumption, glucose oxidation, and pyruvate formation in the cerebral slices of the 24-hr-old rats were as much as 150% of that of the 19-day-old fetus. The distribution profile of radioactivity incorporated into the cerebral amino acids from the subarachnoid-injected [U-14C]glucose was also changed. In the 2- and 6-hr-old rats, 50% of the total radioactivity recovered in the free amino acids was in alanine. Its rate decreased to 30% in the 24-hr-old and was 2% in the adult, while the radioactivity incorporated into glutamic acid increased. Alanine aminotransferase activity started to increase at birth and had the highest level at 24 hr after birth. It then decreased and finally reached the same level as shown at birth. However, aspartate aminotransferase increased during the first 6 hr after birth and did not change until the end of the first day of life.
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PMID:Perinatal changes in amino acid metabolism of rat brain, especially alanine and glutamic acid. 746 80

L-Glutamate is the immediate precursor of the inhibitory transmitter GABA, and considered to be supplied from alpha-ketoglutarate through a transamination reaction or from glutamine through a glutaminase reaction. In the present study, the localization of aspartate aminotransferase and glutaminase in GABAergic neurons was investigated in the rat neocortex by a double immunofluorescence method. Immunoreactivities for both soluble and mitochondrial aspartate aminotransferases were detected in more than 90% of GABA-positive neurons, whereas glutaminase immunoreactivity was not found in GABA-positive neurons. All neocortical neurons with soluble aspartate aminotransferase immunoreactivity were immunopositive for GABA, but none for glutaminase. Neurons with mitochondrial aspartate aminotransferase immunoreactivity showed either glutaminase or GABA immunoreactivity. Under confocal laser scan microscopy, immunoreactivity for soluble aspartate aminotransferase was observed in many axons and axon terminals showing immunoreactivity for glutamic acid decarboxylase, whereas immunoreactivity for mitochondrial aspartate aminotransferase was seen in only a few axons displaying immunoreactivity for glutamic acid decarboxylase. The present results indicate that soluble aspartate aminotransferase is selectively localized to cell bodies and axon terminals of GABAergic non-pyramidal neurons in the cerebral neocortex. This suggests that glutamate is supplied from alpha-ketoglutarate via transamination and works as the immediate precursor for GABA in axon terminals of GABAergic neurons. The absence of glutaminase immunoreactivity in GABAergic neurons indicates that glutamine is a "metabolically remote" precursor for GABA. Mitochondrial aspartate aminotransferase was located in perikarya, rather than in axon terminals of GABAergic neurons, suggesting a transmitter-irrelevant role of this enzyme in neurons.
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PMID:Glutamate-synthesizing enzymes in GABAergic neurons of the neocortex: a double immunofluorescence study in the rat. 783 83

Pathophysiological concentrations of ammonia, both in vivo and in vitro, suppressed the oxidation of glutamate by rat cerebellar mitochondria. The transport of glutamate into mitochondria was either unaltered or enhanced during hyperammonemic states. Activities of mitochondrial enzymes, aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase, glutaminase, and GABA-transaminase were suppressed during hyperammonemic states. Suppression of 14CO2 production with (aminooxy)acetic acid but not with glutamic acid diethyl ester indicated that transamination but not oxidative deamination of glutamate plays a major role in glutamate oxidation during normal and hyperammonemic states.
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PMID:Transport and metabolism of glutamate by rat cerebellar mitochondria during ammonia toxicity. 810 3

In a chronic toxicity study in the rat, bidisomide administered as a dietary admixture produced a dose-related lowering of reticulocytes and leucocytes. Plasma alanine aminotransferase activity was increased at 300 mg/kg and decreased at 900 mg/kg. The potential mechanisms of these effects were investigated by comparing the responses in groups of male Sprague-Dawley rats receiving a control diet, or 300 or 1200 mg/kg/day bidisomide. Subsets of these groups were co-treated subcutaneously with folinic acid or with a vitamin B1, B6, B12 complex. Subsets of control and 300 mg/kg groups were maintained on a 20-25% feed restriction regimen for 3 months, to mimic the depression in body weight gain observed in animals receiving 1200 mg/kg. Body weight gains were significantly reduced at 1200 mg/kg and in all feed-restricted animals. Plasma and liver alanine aminotransferase (ALT) and plasma aspartate aminotransferase (AST) levels were also reduced at this dose level. At 300 mg/kg, plasma transaminases, glutamate dehydrogenase (GLDH) and sorbitol dehydrogenase (SDH) activities were increased. These changes were prevented in animals receiving folinic acid supplementation. Plasma glucose, triglycerides, and unsaturated and total iron binding capacities were decreased, while plasma iron levels tended to increase, mainly at the high dose. Vitamin supplementation prevented a decrease in reticulocyte counts at 300 mg/kg. Bidisomide increased urinary formimino-glutamic acid (FIGLU) excretion but did not affect methylmalonic acid (MMA) or taurine excretion. The effect on FIGLU at 1200 mg/kg was prevented by folinic acid co-treatment. Absolute liver weight was lowered at both dose levels and in feed-restricted animals. However, the relative liver weights were unaffected. Thymidine kinase and thymidylate synthase activity of the bone marrow cells were not altered by the bidisomide treatment. Except for the increase in plasma transaminase, GLDH and SDH levels at 300 mg/kg, changes in clinical chemistry parameters are considered to result mainly from nutritional restrictions. Changes in hematologic parameters appear to be related to the combination of decreased feed consumption (leukocytes) and decreased availability or utilization of folates (reticulocytes). This alteration, however, did not affect DNA synthesis in bone marrow. The prevention by folinic acid, but not by feed restriction, of the elevation of liver enzymes at 300 mg/kg is an intriguing, yet unexplained finding. There was no evidence that bidisomide affected B6 and B12 availability.
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PMID:Effect of folate supplementation on clinical chemistry and hematologic changes related to bidisomide administration in the rat. 858 20

The protective effect of dietary L-glutamine against the hepatotoxic action of D-galactosamine (GaIN) was investigated by model experiments with rats. Rats fed with 20% casein diets containing 10% free amino acids were injected with GaIN, and the serum aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities and the hepatic glycogen content were assayed 20 hours after the injection. These enzyme activities in the group fed with 10% L-glutamine diet for 8 days were lower than those in the groups fed with the control, 10% L-glutamic acid and 10% L-alanine diets for 8 days. The more prolonged the feeding period with the 10% L-glutamine diet was, the more the serum activity levels of such enzymes were decreased. Although neomycin also lowered these enzyme activities, its simultaneous ingestion with neomycin did not show any additive or synergistic effect. The hepatic glycogen content in the 10% glutamine group still remained high after the GaIN treatment. It is therefore assumed that the effectiveness of glutamine intake would have been mediated by glycogen metabolism rather than by uridine metabolism.
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PMID:Effect of dietary L-glutamine on the hepatotoxic action of D-galactosamine in rats. 898 89

The activity of aspartate aminotransferase, glutamate dehydrogenase in the liver of rats in 1, 7 and 15 days after gamma irradiation effect of the dose of 0.5 Gy on the background of consumption by animals of sodium nitrate, sodium nitrite and nitrosodiethylamine was studied. The combined influence of chemical agents and gamma irradiation modified the effects of nitro compounds-xenobiotics on processes of the synthesis and dissociation of the glutamic acid as well as the intensity of transamination of the reamination by aspartate aminotransferase.
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PMID:[The combined action of ionizing radiation and nitro compounds on the activity of the basic enzymes of glutamic acid metabolism]. 968 35

Chronic occupational exposure to organophosphorus and carbamate-type pesticides significantly inhibits acetylcholinesterase activity and causes morbidity. This study on mice was designed to evaluate their amino profile and to identify signs of hepatic dysfunction following their chronic exposure to mixtures of organophosphorus pesticides. Laboratory mice were exposed to a formulated mixture of the six organophosphorus pesticides (Dimethoate, Chlorpyrifos, Profenofos, Pirimiphos methyl, Triazophos and Dimethoate) most commonly used in agriculture in this region of the Middle East. Doses (10% of LD50 of the mixture) were given once a week by gavage in corn oil for 7 weeks; the control group was given only corn oil. At the end of the exposure period, mice were culled and blood samples were collected to determine erythrocyte acetylcholinesterase activity, biochemical markers of liver function and concentrations of serum amino acids. Erythrocyte acetylcholinesterase activity and total serum proteins decreased significantly in the exposed group. Serum concentrations of alanine aminotransferase and aspartate aminotransferase, alanine, glutamic acid, glycine, isoleucine, leucine, methionine, ornithine, proline, serine, threonine and valine were significantly increased in the exposed mice, while serum levels of cystine were decreased significantly. There were also non-significant increases in serum alkaline phosphatase, gama-glutamyl transpeptidase and some of the other amino acids. Chronic exposure to mixtures of organophosphorus pesticides is associated with decreased acetylcholinesterase activity, hepatic dysfunction and disturbance of amino acids profile. Biochemical indices of hepatocellular injury and disturbed amino acid metabolism may be of value as markers of chronic exposure to such pesticides.
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PMID:Hepatic injury and disturbed amino acid metabolism in mice following prolonged exposure to organophosphorus pesticides. 1002 66

To examine what causes increased viscosity in culture broth in Streptomyces fradiae culture, various natural nitrogen sources were investigated. Extracellular protease activity increased with culture time and decomposed the natural nitrogen source into amino acids. In the case of gluten meal, after a culture time of 5 d, concentrations of glutamic acid and aspartic acid had increased to 600 and 200 mg/L, respectively, which were about 3- and 2-fold as high as levels in cultures under similar conditions using Pharmamedia. For various amino acids tested, the addition of glutamic acid or aspartic acid mixture to the culture medium raised the apparent viscosity to its highest demonstrated value, 260 mPa.s after 5 d of culture, which was 3-fold higher than without amino acids. Consumption of the decomposed glutamic acid and aspartic acid was dependent on the activities of glutamate dehydrogenase and aspartate aminotransferase, respectively. When ammonium ion was used as the nitrogen source, cell concentration reached 1.75 g/L measured as an intracellular nucleic acid concentration, which was about 2.3-fold higher than that with any other natural nitrogen source. However, apparent viscosity was only 75 mPa.s, a value one-third that of the amino acid mixture, and 70% of the pellets were bigger than 1.2 x 10(4) microm(2). In the case of gluten meal or the amino acid mixture, pellets bigger than 1.2 x 10(4) microm(2) comprised only 8%. This demonstrates that consumption of some amino acids affected the formation of filamentous morphology, which caused an increase in the apparent viscosity of the culture broth, and the apparent viscosity was not caused by the mycelial concentration but the mycelial morphology.
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PMID:Dependence of apparent viscosity on mycelial morphology of Streptomyces fradiae culture in various nitrogen sources. 1093 23

Our hypothesis was that, because horses have not evolved as fat eaters, there may be negative metabolic long-term effects of feeding a high fat diet. The objective of the present study was to identify these long-term effects and compare them with the effects of isoenergetic long-term high starch feeding. This randomised block study with 20 exercised horses looked at the effect of feeding either a high starch (HS) or a high fat (HF) diet type in 3 periods during stabling (Stable 1), pasture, and stabling (Stable 2) over 390 days. The horses received a HS or HF concentrate, straw, hay and 6 h pasture/day in the pasture period. HF horses gained weight (2% of initial bwt) and, therefore, fat intake was reduced (from 1.43 to 0.88 g/kg bwt/day). Blood plasma glucose, total protein, albumins, gamma-globulins, free fatty acids, phospholipids and cholesterol concentrations were higher but urea concentration was lower with HF compared to HS feeding (P<0.05). Plasma concentrations of triglycerides, bilirubin and pre-beta lipoproteins were unaffected by the diet type. There were period effects (P<0.05) for all variables except triglycerides and pre-beta lipoproteins. In contrast to HS, in HF the quotient alpha/beta lipoproteins rose (P<0.05) throughout the stable periods and decreased (P<0.05) during 'pasture'. Glutamic acid dehydrogenase, gamma-glutamyl transferase, alkaline phosphatase, aspartate aminotransferase, creatine kinase and lactate dehydrogenase activity in sera were within the normal range. In conclusion, on the precondition that substantial bodyweight changes were prevented, no apparent adverse effects of long-term high fat feeding were identified and there were no apparent disadvantages of feeding on high fat compared with high starch diets.
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PMID:Effect of feeding exercised horses on high-starch or high-fat diets for 390 days. 1240 59

The homology of subunit primary sequence of 40 glutamate decarboxylases (GAD) of different origin was analyzed by multiple alignment. A phylogenetic tree was designed on the basis of the resulting data. The following groups are distinguished in the consensus tree: archeans, bacteria, plant eukaryotes, and animal eukaryotes. The latter are clearly divided into two branches according to two enzyme isoforms. Borders of PLP domains in each enzyme were detected. The consensus phylogenetic tree for PLP domains is structurally rather similar to that obtained for subunits. Twenty homologous motifs of from 15 to 87 amino acid residues were revealed in all GAD studied. The results revealed the division of all of the enzymes into groups with characteristic sets of motifs in each and a fixed order of their arrangement along the sequence. Thus, we can show the divergent evolution of the enzyme. The results of multiple alignments during structural analysis of the 40 GAD confirmed and extended our previous data on conserved residues that arrange the position of the coenzyme (PLP) in the enzyme active center. The following residues should be noted: lysine forming a Schiff base with the PLP aldehyde group, an adjacent histidine, and aspartic acid that establishes a link with nitrogen of the PLP pyridine ring. The homology of the primary sequence fragments was also found in the residues in contact with the PLP phosphate group. Comparison of the GAD amino acid sequence with that of another PLP enzyme, aspartate aminotransferase, revealed a binding site for carboxylic group of the substrate--glutamic acid. The structures carrying out a particular catalytic function of all GAD studied were detected, i.e., convergent evolution of the enzyme was revealed.
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PMID:Glutamate decarboxylase: computer studies of enzyme evolution. 1246 Jan 16


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