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 time course of changes in concentration of renal metabolites in response to a non-toxic load of NH4 as NH4 Cl or NH4HCO3 were measured in fasted rats. 2) Following a NH4Cl load, decrease of renal concentration of 2-oxoglutarate occurs but this change is delayed in relation to the peak of the blood ammonia concentration and persists after disappearance of the hyperammoniemia. 3) Following a NH4HCO3 load, the oxoglutarate concentration changes are less marked and more transient. 4) No close relationship between the mitochondrial free NAD/NADH ratio calculated from the glutamate dehydrogenase and the 3-hydroxybutyrate dehydrogenase systems were seen during alteration of the ammonia concentration. 5) Contrary to the observations in the liver under similar circumstances (BROSNAN, J.T. et al.: Biochem.J. 138, 453, 1974), no increase in kidney tissue or renal venous blood alanine or aspartate concentration are seen. 6) A constant infusion of NH4HCO3 resulted only in an increase in tissue and renal venous blood glutamine concentration. 7) The infusion of NH4 together with a carbon source (malate) resulted in a similar increase in tissue glutamine concentration and more striking increase in renal venous glutamine concentration. No accumulation of aspartate nor alanine were seen. 8) In vitro studies indicate that the net flux through both the aspartate aminotransferase and the glutamate dehydrogenase reactions is dependent on the concentration of the reactants as expected for a near-equilibrium system. 9) It is concluded that the kidney response to an ammonia load differs from that of the liver despite the existence of a similar network of near-equilibrium reactions of (1) a lack of local availability of oxaloacetate, (2) a lower activity of alanine aminotransferase, (3) a greater in vivo activity of glutamine synthetase.
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PMID:Effect of an ammonia load on the kidney near-equilibrium systems in the rat in vivo. 18 80

The levels of several enzymes have been studied during sporulation of Saccharomyces cerevisia. The specific activities of ribonuclease and aminopeptidase I raised several-fold after transfer of the cells to sporulation medium, whereas the specific activities of phosphofructokinase, glucose-6-phosphate dehydrogenase, tryptophan synthase and pyruvate decarboxylase were not significantly altered. The specific activities of NAD-dependent glutamate dehydrogenase, isocitrate lyase, malate dehydrogenase and fructose bisphosphatase all decreased from the onset of sporulation. The inactivation of these latter enzymes was inhibited by cycloheximide and by inhibitors of energy metabolism. Hexokinase, alcohol dehydrogenase and glutamate oxaloacetate transaminase were partially lost from the cells during the period of ascus maturation. None of the enzyme changes observed proved to be 'sporulation-specific' in that it occurred exclusively in sporulating diploid yeast cells. Therefore it is postulated that the meiotic events and the metabolic changes required for ascospore formation are under separate genetic control in this organism. During sporulation, the cellular content of cytochromes b, c, and aa3 was reduced to 20% or less of that present in vegetative derepressed cells. Since the relative percentage of total to cycloheximide-insensitive mitochondrial protein synthesis was not significantly altered throughout sporulation, and the pattern of mitochondrially synthesized polypeptides was rather similar both in vegetative and in sporulating cells, it appeared that not only degradation but also synthesis and therefore turnover of the mitochondrially coded polypeptides of cytochromes b and aa3 took place during sporulation. The activity ratio of cytochrome c oxidase to F1-ATPase in submitochondrial particles isolated from vegetative cells and from purified asci was almost identical. This indicates that the loss of membrane-bound mitochondrial cytochromes during sporulation is probably due to a nonselective degradation of inner mitochondrial membrane proteins.
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PMID:Protein degradation during yeast sporulation. Enzyme and cytochrome patterns. 18 44

Lactate production by liver slices from fetal rats (17th--18th day of gestation) is enhanced about two fold by aminooxyacetate, an inhibitor of aspartate transaminase (EC 2.6.1.1). Such an effect is consistent with an increase of the cytosolic NAD-redox state owing to the parallel fall in the pyruvate level, whereas the glycolytic flux does not seem to be influenced appreciably. Indeed, although the inhibitor causes a marked increase of fructose 1,6-diphosphate, glucose-6-phosphate decreases only slightly. These results suggest that in fetal rat liver the malate-aspartate shuttle is operative in the reoxidation of cytosolic NADH produced during aerobic glycolysis.
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PMID:The operation of the malate-aspartate shuttle in the reoxidation of glycolytic NADH in slices of fetal rat liver. 20 12

The activities of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP oxidoreductase, G6PD), 6 phosphate glucono dehydrogenase (6 phospho-D-gluconate: NADP oxidoreductase, 6PGD) lactate dehydrogenase (D-lactate: NAD oxidoreductase, LDH), glutamate oxaloacetate transaminase (L-aspartate: 2-oxo-glutarate aminotransferase, GOT) and hexokinase (ATP: D-hexo-6-phosphotrans-ferase, Hx) were measured over 24 h in isolated lymphocytes of normal subjects and in white cells of patients with chronic lymphatic leukaemia (CLL). The activitty patterns of all enzymes in the normal lymphocytes were similar. A computed pattern of all the results exhibited a circadian rhythm of activity with the highest level at 16.00 hours. The oscillations in the activities of the same enzymes in the CLL cells differed among the patients, although all the enzymes of the same individual showed a similar diurnal rhythmic pattern. All peaks in this group appeared between 20.00 and 08.00 hours. The possible importance of these observations in setting up therapeutic schedules was raised.
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PMID:Blood leucocyte enzymes. III. Diurnal rhythm of activity in isolated lymphocytes of normal subjects and chronic lymphatic leukaemia patients. 98 50

The activities of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP oxidoreductase, G6PD), 6-phosphogluconate dehydrogenase (6-phospho-D-gluconate: NADP oxidoreductase, 6PGD), hexokinase (ATP: D-hexose 6-phosphotransferase, Hx), lactate dehydrogenase (D-lactate: NAD oxidoreductase, LDH). glutamate oxaloacetate transaminase (L-aspartate: 2 oxoglutarate aminotransferase, GOT) and dihydrofolate reductase (DHFR) were measured at 8 a.m. in leucocytes of healthy individuals and patients with chronic myeloid leukaemia (CML), chronic lymphatic leukaemia (CLL), myelofibrosis with myeloid metaplasia and polycythaemia vera. In view of the heterogeneity of the leucocyte populations in these conditions, the enzyme activities were correlated to the number of immature cells in CML and to the percentage of lymphocytes in CLL. No differences in the enzyme activities were found between the white cells of healthy individuals, myelofibrosis with myeloid metaplasia and polycythaemia vera. In CML the activities of all enzymes except GOT correlated directly with the number of immature cells; an inverse correlation with the number of lymphocytes was observed in CLL. GOT was the only enzyme whose activity correlated with the number of lymphocytes in the cell suspension. Furthermore, a significantly higher activity of this enzyme was found in Ficoll-isolated CLL lymphocytes as compared to normal lymphocytes.
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PMID:Blood leucocyte enzymes. II. Activities at 8-9 a.m. in cells of normal subjects, chronic lymphatic leukaemia and chronic myeloid leukaemia patients. 105 70

The cytosolic and mitochondrial isozymes of aspartate aminotransferase (AspAT) function in the C4 dicarboxylate cycle of photosynthesis. We constructed a cDNA library from leaf tissues of Panicum miliaceum, an NAD-malic-enzyme-type C4 plant and screened the library for AspAT isozymes. A full-length cDNA clone for cytosolic AspAT was isolated. This clone contains an open reading frame that encodes 409 amino acids. We also isolated two cDNA clones for different precursors of mitochondrial AspAT. Comparing these two sequences in the coding regions, we found 12 amino acid substitutions out of 28 base substitutions. The encoded amino acid sequences predict that mitochondrial AspAT are synthesized as precursor proteins of 428 amino acid residues, which each consist of a mature enzyme of 400 amino acid residues and a 28-amino-acid presequence. This prediction coincides with the observation that the in vitro translation product of the mRNA for mitochondrial AspAT was substantially larger than the mature form. A comparison of the amino acid sequences of the AspAT isozymes from P. miliaceum with the published sequences for the enzymes from various animals and microorganisms reveals that functionally and/or structurally important residues are almost entirely conserved in all AspAT species.
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PMID:Cloning and sequence analysis of cDNA encoding aspartate aminotransferase isozymes from Panicum miliaceum L., a C4 plant. 154 Dec 76

The subcellular localization of NAD- and NADP-linked glutamate dehydrogenases (GDH-NAD and GDH-NADP), alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) in epimastigotes of Trypanosoma cruzi was studied by digitonin extraction from whole cells, subcellular fractionation by differential centrifugation and isopycnic ultracentrifugation. All enzymes presented both a cytosolic and a mitochondrial form; in addition, GDH-NADP seems to have a third, still undefined, localization. The results are compatible with the existence of two pathways for the production of L-alanine linked to the reoxidation of glycolytic NADH, one operative in the mitochondrion and the other in the cytosol, and perhaps responsible for the existence of the two alanine pools detected by 13C-nuclear magnetic resonance (B. Frydman et al., Eur. J. Biochem. 192 (1990) 363-368).
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PMID:Subcellular localization of glutamate dehydrogenases and alanine aminotransferase in epimastigotes of Trypanosoma cruzi. 177 28

The activities of serum malate dehydrogenase (MDH) and its mitochondrial isoenzyme (MDHm) were studied in sera of patients with liver disease. They proved to be more useful than those of aspartate aminotransferase (AST) and its mitochondrial isoenzyme for detection of hepatocellular carcinoma and acute circulatory failure, and for estimation of the severity of acute hepatitis. The N/T value measuring system, which is adaptable for autoanalysis and allows simultaneous determination of activities depending on NAD and thionicotinamide adenine dinucleotide (thio-NAD), yields both the total activity of MDH and the N/T value which was correlated significantly with MDHm/MDH (r = 0.748). Assay of MDH and its mitochondrial isoenzyme in association with the N/T value measuring system seems to be more useful and less time consuming for estimation of the severity of liver diseases than that of AST and its mitochondrial isoenzyme.
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PMID:Clinical usefulness of malate dehydrogenase and its mitochondrial isoenzyme in comparison with aspartate aminotransferase and its mitochondrial isoenzyme in sera of patients with liver disease. 217 15

This investigation presents disturbances of the mitochondrial metabolism by arsenite, a hydrophilic dithiol reagent known as an inhibitor of mitochondrial alpha-keto acid dehydrogenases. Arsenite at concentrations of 0.1-1.0 mM was shown to induce a considerable oxidation of intramitochondrial NADPH, NADH, and glutathione without decreasing the mitochondrial membrane potential. The oxidation of NAD(P)H required the presence of phosphate and was sensitive to ruthenium red, but occurred without the addition of calcium salts. Mitochondrial reactions producing alpha-ketoglutarate from glutamate and isocitrate were modulated by arsenite through various mechanisms: (i) both glutamate transaminations, with oxaloacetate and with pyruvate, were inhibited by accumulating alpha-ketoglutarate; however, at low concentrations of alpha-ketoglutarate the aspartate aminotransferase reaction was stimulated due to the increase of NAD+ content; (ii) the oxidation of isocitrate was stimulated at its low concentration only, due to the oxidation of NADPH and NADH; this oxidation was prevented by concentrations of citrate or isocitrate greater than 1 mM; (iii) the conversion of isocitrate to citrate was suppressed, presumably as a result of the decrease of Mg2+ concentration in mitochondria. Thus the depletion of mitochondrial vicinal thiol groups in hydrophilic domains disturbs the mitochondrial metabolism not only by the inhibition of alpha-keto acid dehydrogenases but also by the oxidation of NAD(P)H and, possibly, by the change in the ion concentrations.
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PMID:A complex effect of arsenite on the formation of alpha-ketoglutarate in rat liver mitochondria. 227 50

The NAD analog 3-acetylpyridine adenine nucleotide (APAD), because of its higher oxidation potential, has proven useful for the direct enzymatic measurement of such compounds as lactate, malate, glutamate, etc., for which the equilibrium with NAD+ as oxidant is unfavorable. An enzymatic cycling method which is capable of increasing the sensitivity of such reactions 10,000-fold or more is described. The APADH produced in the original stoichiometric reaction is used to catalyze a cycling reaction that employs lactate and malate dehydrogenases (EC 1.1.1.27 and EC 1.1.1.37) to generate (from lactate plus oxalacetate) very large quantities of pyruvate and malate. After the cycling step, the malate formed is measured with NAD+ and with malate dehydrogenase, plus aspartate aminotransferase, and oxaloacetate to pull this indicator reaction to completion. The application of this cycling method is illustrated by analysis of malate in the range 1 to 10 pmol.
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PMID:An enzymatic cycling method for 3-acetylpyridine adenine dinucleotide to increase the sensitivity of enzymatic methods which employ this NAD analog. 236 93


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