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)

1. The utilization of amino acids for gluconeogenesis by rat liver develops in postnatal life, reaching maximum activity at the fifth day. 2. The activity of aspartate transaminase shows a similar trend in postnatal development and the increased activity appears to be due to the soluble enzyme. 3. The activity of alanine transaminase is low in foetal and postnatal rat liver and increases in activity at about the twentieth day. 4. Aspartate, glutamate and alanine make a major contribution to gluconeogenesis in the postnatal rat liver.
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PMID:Gluconeogenesis from amino acids in neonatal rat liver. 604 92

We measured amino acid contents in the brains of 11 patients with dominantly inherited cerebellar disorders. Despite clinical similarities, three biochemically different disorders were found. One disorder, with demonstrated HLA linkage in one pedigree, was characterized by moderate reduction of aspartate and glutamate contents in cerebellar cortex alone. In a second disorder, aspartate and glutamate contents were reduced markedly in other brain areas as well as in cerebellar cortex. Aspartate and glutamate contents were normal in cerebellar cortex in the third disorder. GABA content in cerebellar cortex and dentate nucleus was reduced in some patients with each disorder, whereas cerebellar taurine content was normal in all patients. Aspartate deficiency in cerebellar cortex did not result from lack of aspartate aminotransferase or pyruvate carboxylase activity. These amino acid abnormalities probably imply loss of specific cerebellar neurons.
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PMID:Neurotransmitter amino acids in dominantly inherited cerebellar disorders. 611 Oct 44

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 activities of prolyl hydroxylase (Pro-OHase), galactosylhydroxylysyl glucosyltransferase (Glu-Gal-Hyl-Tase), and hydroxylysyl galactosyltransferase (Gal-Hyl-Tase) were assayed in lung tissues of hamsters with bleomycin-induced experimental pulmonary fibrosis. Serum Glu-Gal-Hyl-Tase and aspartate transaminase (Asp-NH2-Tase) were measured in the same animals. Lung fibrosis was induced by intratracheal bleomycin instillation, and the enzyme activities were assayed 2, 3, and 4 weeks after bleomycin administration. The activities of the three lung enzymes increased significantly after bleomycin instillation. However, no difference in the values of serum Glu-Gal-Hyl-Tase or Asp-NH2-Tase were observed. Histologic examination of lung sections indicated progressive fibrotic foci. These results thus indicate that the activities of collagen processing enzymes are elevated in the fibrotic lung tissues as a reflection of the increased rate of collagen synthesis during the period of active fibrogenesis, but unlike liver fibrosis, the elevation of tissue Glu-Gal-Hyl-Tase is not predicted by a corresponding increase in serum levels of this enzyme.
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PMID:Enzymes of collagen synthesis in lung tissues of bleomycin-induced pulmonary fibrosis. 620 Sep 53

The effects of cellulose, pectin and bran on the bioavailability of pyridoxine (PN) were examined using rat and chick bioassay methods. Dose-response curves for growth, feed consumption, feed efficiency and either lever pyridoxal 5'-phosphate (PLP) or erythrocyte aspartate aminotransferase (Asp-AT) activity and PLP stimulation in vitro were compared among animals fed experimental diets varying in dietary fiber source and suboptimal levels. of PN. In rats, the observed stimulation of growth and feed efficiency by pectin, as compared to cellulose, at suboptimal PN levels was attributed to increased synthesis of vitamin B-6 intestinal microflora. Diets containing pectin markedly increased the fecal vitamin B-6 content. No difference in liver PLP was detected among rats fed various diets. In chicks, 5% dietary pectin resulted in increased feed consumption, but also diarrhea and depressed growth. Asp-AT activities at the lower level of dietary PN showed a significant (P greater than 0.05) but modest stimulating effect of pectin on the apparent bioavailability of PN. Bran resulted in a 17% bioavailability decrease of PN as indicated by growth and feed consumption data in the chick. However, no difference in Asp-AT activity or in vitro PLP stimulation was detected in comparison of responses from bran-fed chicks with the standard responses. These results suggest that the polysaccharides tested did not have important deleterious effects on the bioavailability of pyridoxine.
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PMID:Effects of selected polysaccharides on the bioavailability of pyridoxine in rats and chicks. 626 37

The cytoplasmic isozyme of aspartate transaminase is inactivated by trypsin due to loss of a 19-residue peptide from the NH2-terminal region. A second peptide bond at Arg-25 is then cleaved by trypsin leaving a residual core protein, transaminase 26-412. Inactivation by trypsin resembles that for the mitochondrial enzyme (Sandmeier, E., and Christen, P. (1980) J. Biol. Chem. 255, 10284-10289), yet occurs 10 times faster for the cytoplasmic isozyme. In the mitochondrial enzyme, trypsin cleavage produces equal concentrations of proteins missing the first 26 and 31 amino acids. Sequence variation in the NH2-terminal regions can explain such differences. Specifically, the mitochondrial NH2 terminus has no trypsin-susceptible residue at position 19 and is stabilized by an electrostatic interaction between Asp-15 and Arg-292, whereas position 15 is a valyl residue in the cytoplasmic enzyme. Calorimetric data reveal both a decreased transition temperature (Td) and enthalpy (delta Hd) of denaturation in transaminases 20-412 and 26-412. Interaction of substrates with the active site chromophore and differential scanning calorimetry (DSC) reveal that catalytically inactive transaminases 20-412 and 26-412 can bind amino acid substrates and produce spectroscopically detectable conversion of the pyridoxal to the pyridoxamine form of the protein. By contrast, substrate analogs only form enzymatic Michaelis-type complexes.
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PMID:Selective tryptic cleavage of native cytoplasmic aspartate transaminase holoenzyme. 636 6

The degree of hepatotoxicity induced by halothane in hypoxic (14% inspired oxygen), enzyme-induced (phenobarbitone treatment for 10 days), male Sprague-Dawley rats was assessed by histological examination and analysis of serum aspartate aminotransferase (Asp. AT) concentrations. There was a significant direct, linear relationship between dose of halothane and histology score (P = 2.96 X 10(-5), and Asp. AT concentration (P = 4.8 X 10(-5) ). The effect of administration of nitrous oxide before (70%) and during (86%) hypoxia was tested for in the presence and absence of 0.75% halothane. Nitrous oxide was found to produce no effect in the absence of halothane, but to potentiate the hepatotoxicity of 0.75% halothane (P = 0.0003 for Asp. AT and 0.0016 for histology scores). The possible mechanisms of this effect are discussed.
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PMID:Effect of nitrous oxide on halothane-induced hepatotoxicity in hypoxic, enzyme-induced rats. 672 61

Aspartate: 2-oxoglutarate aminotransferase [EC 2.6.1.1] was purified and crystallized from bakers' yeast. The crystalline preparation gave a single band on polyacrylamide disc gel electrophoresis in the presence of sodium dodecyl sulfate. However, in the absence of sodium dodecyl sulfate, the preparation gave one major band with two faint bands, all of which showed the same specific activity, molecular weight and serological properties. These faint bands appeared to be modified forms produced from the major band during the purification. The enzyme showed a molecular weight of 90,000 +/- 8,000 and 92,000 +/- 8,000 by gel filtration and sedimentation equilibrium analysis, respectively. The molecular weight of a subunit was estimated to be 45,000 by sodium dodecyl sulfate slab gel electrophoresis. Each subunit bound approximately 1 mol of pyridoxal 5'-phosphate. The bound pyridoxal 5'-phosphate showed an absorption maximum at 360 nm (epsilon M: 11,500) and 430 nm (epsilon M: 8,200) in alkaline and acidic conditions, respectively. Its proteolytic pK was pH 6.3. The enzyme showed an optimum pH of 8.0-9.0, and fairly high amino donor and acceptor specificities; aromatic amino acids and their corresponding 2-oxoacids were catalyzed at rates of 0.2-0.8% of those for aspartate and oxalacetate, respectively. Michaelis constants for various substrate were: L-aspartate (0.11 mM), L-glutamate (20.0 mM), oxalacetate (0.006 mM), and 2-oxoglutarate (0.16 mM). The antiserum against yeast aspartate aminotransferase did not form precipitin bands with homogeneous aspartate aminotransferases from pig heart cytosol, pig heart mitochondria or Escherichia coli B.
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PMID:Aspartate: 2-oxoglutarate aminotransferase from bakers' yeast: crystallization and characterization. 681 76

The effects of intraperitoneal administration of (S)-4-amino-5-fluoropentanoic acid, a mechanism-based covalent inactivator of gamma-aminobutyric acid transaminase (GABA-T), on whole brain GABA metabolism in mice were investigated. A dose-dependent and time-dependent irreversible inactivation of GABA-T was observed with a concomitant increase in whole brain GABA levels. The compound exhibited no in vitro nor in vivo time-dependent inhibition of glutamate decarboxylase (GAD), alanine transaminase, or aspartate transaminase (Asp-T). It was, however, a potent competitive reversible inhibitor of GAD and a weak competitive inhibitor of Asp-T. The chloro analogue, (S)-4-amino-5-chloropentanoic acid, was ineffective.
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PMID:In vitro and in vivo effects on brain GABA metabolism of (S)-4-amino-5-fluoropentanoic acid, a mechanism-based inactivator of gamma-aminobutyric acid transaminase. 685 67

Mitochondrial aspartate transamination was investigated as a major source of oxalacetate for citrate synthesis in rat ventral prostate. Citrate accumulation was measured in isolated mitochondria incubated with acetyl coenzyme A and various combinations of amino acids. Aspartate plus alpha ketoglutarate in the presence of acetyl coenzyme A resulted in significant citrate accumulation. Neither aspartate nor alpha ketoglutarate alone resulted in any significant citrate accumulation. Aspartate and alpha ketoglutarate use was comparable to glutamate and citrate production. The results indicated the presence of a mitochondrial aspartate aminotransferase. Castration (3 days) caused a significant decrease in citrate production from aspartate plus alpha ketoglutarate as well as a decrease in mitochondrial AAT activity in prostate although no effect on kidney activity occurred. A single injection of 1 mg. testosterone propionate to castrate rats significantly increased prostate mitochondrial AAT activity within 24 hours while MDH activity was unaltered. A double reciprocal plot indicated that testosterone might regulate the level of mitochondrial AAT in prostate. Ventral prostate also contain a uniquely high level of endogenous aspartate. These studies indicate that aspartate might be the major 4-carbon source of oxalacetate for citrate synthesis. Also testosterone possibly regulated prostate citrate production by its effect on the level of mitochondrial AAT activity.
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PMID:Mitochondrial aspartate aminotransferase and the effect of testosterone on citrate production in rat ventral prostate. 706 60


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