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:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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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PMID:Glutamine metabolism in a holostean (Amia calva) and teleost fish (Salvelinus namaycush). 167 42

Methanosarcina barkeri was able to grow on L-alanine and L-glutamate as sole nitrogen sources. Cell yields were 0.5 g/l and 0.7 g/l (wet wt), respectively. The mechanism of ammonia assimilation in Methanosarcina barkeri strain MS was studied by analysis of enzyme activities. Activity levels of nitrogen-assimilating enzymes in extracts of cells grown on different nitrogen sources (ammonia, 0.05-100 mM; L-alanine, 10 mM; L-glutamate, 10 mM) were compared. Activities of glutamate dehydrogenase, glutamate synthase, glutamine synthetase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase could be measured in cells grown on these three nitrogen sources. Alanine dehydrogenase was not detected under the growth conditions used. None of the measured enzyme activities varied significantly in response to the NH4+ concentration. The length of the poly-gamma-glutamyl side chain of F420 derivatives turned out to be independent of the concentration of ammonia in the culture medium.
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PMID:Ammonia assimilation and glutamate incorporation in coenzyme F420 derivatives of Methanosarcina barkeri. 167 22

Applying catalytic enzyme histochemistry, glutamate dehydrogenase (GDH) and phosphate activated glutaminase (PAG) were demonstrated at the light microscopic level, and aspartate aminotransferase (AAT) was detected at the electron microscopic level. GDH staining appeared preferentially in glial cells (Bergmann glia and astrocytes), whereas AAT was localized only in neuronal structures. Cytoplasmic AAT was demonstrated in the perikarya and terminal plexus of basket cells, in the perikarya of stellate cells, in about 60% of the granule cells, in mossy fiber boutons, in numerous small boutons in the molecular layer, and in the axoplasm of numerous myelinated and unmyelinated fibers. PAG was observed in both neuronal structures (perikarya of granule and Purkinje cells) and in astrocytes and Bergmann glia.
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PMID:Histochemistry of glutamate metabolizing enzymes in the rat cerebellar cortex. 168 39

The inability of the 'ethanol/high vitamin A Lieber-DeCarli diet' to induce liver fibrosis in two different rat strains was further evaluated by determining changes in parameters of liver cell damage and of retinoid and lipid metabolism. In the ethanol/vitamin A-treated group, slight but constant hepatic cell damage, as indicated by elevated alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase activities in blood, was already observed at 6 months and maintained until the time of death at 16 months. Serum gamma-glutamyl transaminase activities were not raised. Moderate parenchymal liver cell damage was not accompanied by fibrosis. Hypertriglyceridemia or hypercholesterolemia were observed at 6-16 months of chronic alcohol administration. This response was strain dependent. In ethanol-treated rats of both strains, total liver retinoids and serum retinol concentrations were not altered. Therefore, the hypothesis that interaction between alcohol and retinoids is a major factor in the pathogenesis of alcoholic liver disease, needs to be reconsidered.
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PMID:Chronic administration of ethanol with high vitamin A supplementation in a liquid diet to rats does not cause liver fibrosis. 2. Biochemical observations. 174 28

In order to gain insight into the metabolic modifications induced in rat brain tissues by helium-neon (He-Ne) laser irradiation, in the research described here, we investigated the variations in the activity of the enzymes aspartate transferase (AST, EC 2.6.1.4), both cytosolic and mitochondrial, glutamate dehydrogenase (GIDH, EC 1.4.1.3), and total superoxide dismutase (SOD, EC 1.15.1.1), in the brain of rats treated with a very small dose (1.08 J) of He-Ne laser radiation. The rats were sacrificed 4 h after the treatment. The enzymes were evaluated spectrophotometrically in brain extracts of irradiated animals and also in untreated rats (controls) and rats that underwent simulated treatment (stressed). The data obtained from 5-10 animals assayed individually showed that, in the in toto brain tissues of the irradiated rats compared to the stressed rats, there was a marked increase of total SOD, together with an appreciable decrease of cytosolic AST, and insignificant variations in mitochondrial AST and GIDH. Stress alone caused a considerable decrease of total SOD and small but statistically significant increases of s-AST, m-AST, and GIDH.
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PMID:Rat brain metabolism enzyme activity variations following He-Ne laser irradiation. 177 92

The effect of cercal deafferentation (cercectomy) on the ganglionic protein metabolism of the cricket, Gryllotalpa africana was studied. Significant changes in the activities of the enzymes acetylcholinesterase, glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase were observed in the terminal ganglion following unilateral and bilateral cercectomy.
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PMID:Cercal sensory regulation of ganglionic protein metabolism in the field cricket, Gryllotalpa africana. 179 75

Seventeen serum markers (including 9 enzyme activities) for eventual tissue damage were studied after ESWL in 40 patients with unilateral kidney calculosis. No changes were established in the 8 non-enzymic parameters and the activities of amylase, lipase, AST (GOT), ALT (GPT) and CK-MB. A statistically significant increase was found in LDH, alpha-HBDH, CK (twice) and glutamate dehydrogenase (3 times). The slight elevation of LDH and alpha-HBDH could be due to haemolysis caused by the shock waves. Increased activity of CK suggested myolysis and that of GlDH a hepatocellular damage.
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PMID:Acute changes of serum markers for tissue damage after ESWL of kidney stones. 188 66

In liver and serum, AST activity is dependent on two isoenzymes, which are mitochondrial and cytosolic in nature. In an attempt to explain the well-known increase of serum mitochondrial AST-to-total AST ratio in chronic alcoholism (which is due to a specific increase of the mitochondrial isoenzyme), we analyzed: (a) liver and serum AST, ALT and glutamate dehydrogenase activities in 23 active drinkers with minimal liver changes, 11 alcoholic patients with cirrhosis who had stopped drinking, 18 nonalcoholic patients with viral chronic hepatitis and 11 subjects with normal livers; and (b) the expression of messenger RNAs for AST isoenzymes in the corresponding liver samples. Enzymatic activities were decreased in the liver irrespective of the origin of the liver disease. In patients with viral chronic hepatitis (or in those with alcoholic cirrhosis when abstinent), variations in liver proteins and messenger RNAs paralleled significant decreases in mitochondrial AST, ALT and glutamate dehydrogenase and a nonsignificant decrease of cytosolic AST. In alcoholic patients with minimal liver changes, the significant decrease of hepatic cytosolic AST, ALT and glutamate dehydrogenase activities contrasted with a close-to-normal liver mitochondrial AST activity; the increased amounts of mitochondrial AST messenger RNA give evidence for a pretranslational mechanism of regulation, indicating a possible increase in the total production of mitochondrial AST in the liver. The decrease of hepatic cytosolic AST activity was statistically significant only in alcoholic patients without cirrhosis who had a normal cytosolic AST mRNA level, thus suggesting a contributory role of translational or posttranslational regulation. In conclusion, regulation of AST isozymes during liver disease is complex, including differential, pretranslational and translational or posttranslational mechanisms.
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PMID:Hepatic activity and mRNA expression of aspartate aminotransferase isoenzymes in alcoholic and nonalcoholic liver disease. 191 63

Changes in the protein metabolism of gill, kidney and intestine of freshwater fish, Cyprinus carpio exposed to 1, 15 and 30 days to sublethal concentration (0.1 mg/l) of mercury were studied. The total, soluble and structural protein contents recorded the depletion followed by progressive increase in accumulation of free aminoacids. Concurrently, the activity of protease in the tissues was also increased. A steady enhancement in the activities of aspartate aminotransferase and alanine aminotransferase paralleled the elevation of glutamate dehydrogenase activity in the organs studied. Levels of ammonia and urea have also reported elevation. All these changes clearly documented the induction of severe proteolysis. The magnitude of these changes increased overtime. These changes were more in the gill at the initial periods of exposure (1 and 15 days), but as the period of exposure increased, these changes were more pronounced in the kidney at 30 days of exposure to sublethal concentration of mercury.
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PMID:Shifts in protein metabolism in some organs of freshwater fish, Cyprinus carpio under mercury stress. 193 Feb 54

Leucine and beta-(+/-)-2-aminobicyclo[2.2.1]heptane-2-carboxylic acid (BCH) stimulated, in a dose-dependent manner, reductive amination of 2-oxoglutarate in rat brain synaptosomes treated with Triton X-100. The concentration dependence curves were sigmoid, with 10-15-fold stimulations at 15 mM leucine (or BCH); oxidative deamination of glutamate also was enhanced, albeit less. In intact synaptosomes, leucine and BCH elevated oxygen uptake and increased ammonia formation, consistent with stimulation of glutamate dehydrogenase (GDH). Enhancement of oxidative deamination was seen with endogenous as well as exogenous glutamate and with glutamate generated inside synaptosomes from added glutamine. With endogenous glutamate, the stimulation of oxidative deamination was accompanied by a decrease in aspartate formation, which suggests a concomitant reduction in flux through aspartate aminotransferase. Activation of reductive amination of 2-oxoglutarate by BCH or leucine could not be demonstrated even in synaptosomes depleted of internal glutamate. It is suggested that GDH in synaptosomes functions in the direction of glutamate oxidation, and that leucine may act as an endogenous activator of GDH in brain in vivo.
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PMID:Activation of glutamate dehydrogenase by leucine and its nonmetabolizable analogue in rat brain synaptosomes. 196 60


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