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

1. The activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenases were measured in nervous tissue from different animals in an attempt to provide more information about the citric acid cycle in this tissue. In higher animals the activities of citrate synthase are greater than the sum of activities of the isocitrate dehydrogenases, whereas they are similar in nervous tissues from the lower animals. This suggests that in higher animals the isocitrate dehydrogenase reaction is far-removed from equilibrium. If it is assumed that isocitrate dehydrogenase activities provide an indication of the maximum flux through the citric acid cycle, the maximum glycolytic capacity in nervous tissue is considerably greater than that of the cycle. This suggest that glycolysis can provide energy in excess of the aerobic capacity of the tissue. 2. The activities of glutamate dehydrogenase are high in most nervous tissues and the activities of aspartate aminotransferase are high in all nervous tissue investigated. However, the activities of alanine aminotransferase are low in all tissues except the ganglia of the waterbug and cockroach. In these insect tissues, anaerobic glycolysis may result in the formation of alanine rather than lactate.
 ...
PMID:Activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenases, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in nervous tissues from vertebrates and invertebrates. 0 Oct 3

Polarization of fluorescence measurements on aspartate aminotransferase (from pig heart cytosol) labeled with fluorescein isothiocyanate have been used to detect the formation of a soluble complex of this protein wich glutamate dehydrogenase from bovine liver. The binding of the labeled transaminase to dehydrogenase is detectable at catalytic concentrations of the enzymes.
 ...
PMID:Fluorescence polarization studies on the binding between glutamate dehydrogenase and cytoplasmic aspartate aminotransferase. 0 87

In previous studies it was found that: (a) aspartate aminotransferase increases the aspartate dehydrogenase activity of glutamate dehydrogenase; (b) the pyridoxamine-P form of this aminotransferase can form an enzyme-enzyme complex with glutamate dehydrogenase; and (c) the pyridoxamine-P form can be dehydrogenated to the pyridoxal-P form by glutamate dehydrogenase. It was therefore concluded (Fahien, L.A., and Smith, S.E. (1974) J. Biol. Chem 249, 2696-2703) that in the aspartate dehydrogenase reaction, aspartate converts the aminotransferase into the pyridoxamine-P form which is then dehydrogenated by glutamate dehydrogenase. The present results support this mechanism and essentially exclude the possibility that aspartate actually reacts with glutamate dehydrogenase and the aminotransferase is an allosteric activator. Indeed, it was found that aspartate is actually an activator of the reaction between glutamate dehydrogenase and the pyridoxamine-P form of the aminotransferase. Aspartate also markedly activated the alanine dehydrogenase reaction catalyzed by glutamate dehydrogenase plus alanine aminotransferase and the ornithine dehydrogenase reaction catalyzed by ornithine aminotransferase plus glutamate dehydrogenase. In these latter two reactions, there is no significant conversion of aspartate to oxalecetate and other compounds tested (including oxalacetate) would not substitute for aspartate. Thus aspartate is apparently bound to glutamate dehydrogenase and this increases the reactivity of this enzyme with the pyridoxamine-P form of aminotransferases. This could be of physiological importance because aspartate enables the aspartate and ornithine dehydrogenase reactions to be catalyzed almost as rapidly by complexes between glutamate dehydrogenase and the appropriate mitochondrial aminotransferase in the absence of alpha-ketoglutarate as they are in the presence of this substrate. Furthermore, in the presence of aspartate, alpha-ketoglutarate can have little or no affect on these reactions. Consequently, in the mitochondria of some organs these reactions could be catalyzed exclusively by enzyme-enzyme complexes even in the presence of alpha-ketoglutarate. Rat liver glutamate dehydrogenase is essentially as active as thebovine liver enzyme with aminotransferases. Since the rat liver enzyme does not polymerize, this unambiguously demonstrates that monomeric forms of glutamate dehydrogenase can react with aminotransferases.
 ...
PMID:Effect of aspartate on complexes between glutamate dehydrogenase and various aminotransferases. 1 47

Biotin deficiency in Aspergillus nidulans resulted in a 70% increase of the protein content and increased levels of free and bound aspartate, glutamate, serine, leucine and methionine. Likewise, the activities of NADP+ glutamate dehydrogenase, NAD+ gluatmate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were significantly increased. The total RNA content increased while the DNA content was unaffected. The rRNA/tRNA ratio remained higher in biotin-deficient cells. Supplementation of glutamate, aspartate, serine, leucine and methionine to the culture medium raised the rRNA/tRNA ratio, and the difference observed in the qualitative and the quantitative patterns of protein and dry cell mass between normal and biotin-deficient cultures was abolished.
 ...
PMID:Factors affecting protein synthesis during biotin deficiency in Aspergillus nidulans. 4 77

Using rats, we studied how best to assess hepatic damage after administering therapeutic doses of each of five anti-cancer drugs or of the hepatotoxin, carbon tetrachloride. As indexes, we compared measurement of the concentration of administered antipyrine in plasma with measurement in serum of alpha-fetoprotein or of the activities of five enzymes that reportedly best reflect hepatic damage. The biological half-life of antipyrine in the plasma was increased more than threefold on pretreating the rats with any of the five cytotoxic drugs or with carbon tetrachloride. In contrast, the concentrations of alpha-fetoprotein, alkaline phosphatase, gamma-glutamyltransferase, or glutamate dehydrogenase were not consistently increased. Of the enzymes tested in serum, aspartate aminotransferase and ornithine carbamoyltransferase best indicated hepatic impairment resulting from the treatment with anti-cancer drugs. Our results imply that determination of the pharmacokinetics of marker drugs such as antipyrine better indicates hepatic dysfunction induced by cytotoxic agents than does measurement of the enzymes liberated into serum as a result of damage to liver mitochondria.
 ...
PMID:Hepatic function assessed (in rats) during chemotherapy with some anti-cancer drugs. 8 82

A tetrazolium staining medium incorporated in a gel has been used in a histochemical study of enzymes in thin sections of heart muscle. Formazan distribution patterns given by mitochondrial enzymes were inconsistent with the location of these enzymes revealed by the extraction of whole tissue. Similar stain distributions were given by lactate dehydrogenase, glutamate oxaloacetate transaminase and glutamate dehydrogenase. The distribution given by succinate dehydrogenase was not the same as that given by cytochrome oxidase stained by a different technique. Alcohol dehydrogenase added to the tissue assumed a distribution which suggested some adsorption of the enzyme to the tissue. But experiments suggested that this enzyme was not firmly bound to muscle proteins in the manner of some glycolytic enzymes.
 ...
PMID:Localization in cardiac muscle of some enzymes related to glutamate metabolism. 16 67

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.
 ...
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.
 ...
PMID:Protein degradation during yeast sporulation. Enzyme and cytochrome patterns. 18 44

Enzymes of parasite origin were identified by starch-gel electrophoresis. The species of parasite studied were Plasmodium berghei, Plasmodium yoelii nigeriensis, Babesia rodhaini and Anthemosoma garnhami. Lactate dehydrogenase, glucose phosphate isomerase and (NADP) glutamate dehydrogenase were detected in all species; phosphogluconate dehydrogenase was detected in both Plasmodium species but malate dehydrogenase only in P. y. nigeriensis. Glucose-6-phosphate dehydrogenase, alanine aminotransferase and aspartate aminotransferase were not detected in any parasite.
 ...
PMID:Biochemistry of intraerythrocytic parasites. I. Identification of enzymes of parasite origin by starch-gel electrophoresis. 38 67

1. The cultured, epimastigote-form of Trypanosoma cruzi contains NADP-linked glutamate dehydrogenase (EC 1.4.1.4), with a molecular weight of about 280,000, similar to the enzyme from Plasmodium chabaudi and different from the enzymes from higher animal sources. 2. T. cruzi also contains aspartate aminotransferase (EC 2.6.1.1), with properties similar to those of the enzyme from mammals. 3. The concerted action of the transaminase and glutamate dehydrogenase might be responsible for the production of NH3 which characterizes the protein catabolism in T. cruzi.
 ...
PMID:Glutamate dehydrogenase and aspartate aminotransferase in Trypanosoma cruzi. 40 Sep 47


1 2 3 4 5 6 7 8 9 10 Next >>