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)

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.
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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.
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PMID:Glutamate dehydrogenase and aspartate aminotransferase in Trypanosoma cruzi. 40 Sep 47

The hepatocyte and haematopoietic cell contents of the liver of the foetal guinea pig were measured over the latter half of gestation. Hepatocytes represented about 30% of liver volume at mid-gestation and this increased to 70-80% by term; cell volume remained fairly constant until 5-7 days before term, then more than doubled. Haematopoietic cells represented about 5% of liver volume at mid-gestation and this progressively fell to <1% by term. At 75% of gestation hepatocytes and haematopoietic cells were prepared from perfused foetal livers by collagenase digestion. Enzyme activity of the hepatocyte was, without exception, similar to that of the whole liver. In general, enzyme activity in the haematopoietic cells was similar to that in erythrocytes, with relatively low values for aldolase, glycerol 3-phosphate dehydrogenase, phosphoglycerate mutase, enolase, lactate dehydrogenase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, isocitrate dehydrogenase, ;malic' enzyme, glutamate dehydrogenase and aspartate aminotransferase. The haematopoietic cell contribution to total enzyme activity in the foetal liver was usually much less than 10% and could thus not account for the major changes in hepatic enzyme activity over the latter half of gestation. Hepatocytes contained hexokinase isoenzymes I and III, aldolase isoenzymes A and B and pyruvate kinase isoenzymes 1, 2 and 4. The haematopoietic cells contained hexokinase isoenzyme I and two additional bands of activity with slightly greater mobility, aldolase isoenzyme A and pyruvate kinase isoenzymes 2 and 4.
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PMID:The distribution of enzyme and isoenzyme activities between parenchymal and haematopoietic cells in the liver of the foetal guinea pig. 43 88

The mitochondrial matrix subfractions from rat liver, kidney cortex, brain, heart, and skeletal muscle were isolated and their protein components were resolved by two-dimensional polyacrylamide gel electrophoresis, revealing between 120 and 150 components for each matrix subfraction. Excellent resolution was obtained utilizing a pH 5 to 8 gradient in the first dimension and in 8 to 13% exponential acrylamide gradient in the second dimension, increasing the number of mitochondrial matrix proteins observed 3-fold over one-dimensional systems. Protein components tentatively identified by co-migration with pure enzymes and by known tissue distributions are carbamoyl-phosphate synthetase (EC 2.7.2.5), ornithine transcarbamylase (EC 2.1.3.3), glutamate dehydrogenase (EC 1.4.1.3), pyruvate carboxylase (EC 6.4.1.1), citrate synthase (EC 4.1.3.7), fumarase (EC 4.2.1.2), aconitase (EC 4.2.1.3), alpha-ketoglutarate dehydrogenase (EC 1.2.4.2), dihydrolipoyl transsuccinylase (EC 2.3.1.12), lipoamide dehydrogenase (EC 1.6.4.3), glutamate-aspartate aminotransferase (EC 2.6.1.1), and the two subunits of pyruvate dehydrogenase (EC 1.2.4.1). Protein components unambiguously identified by peptide mapping are citrate synthase, aconitase, and pyruvate carboxylase. The inner membrane subfraction from rat liver mitochondria was also resolved two dimensionally; the alpha and beta subunits of ATPase (F1) (EC 3.6.1.3) were identified by peptide mapping.
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PMID:Resolution of rat mitochondrial matrix proteins by two-dimensional polyacrylamide gel electrophoresis. 44 63

1. The concentration of HCO3- (independent of any change of pH) exerts different effects on glutamine metabolism in rat kidney-cortex tubules, hepatocytes and enterocytes.2. In kidney tubules HCO3- (10.5-50 MM) has no effect on glutaminase (EC 3.5.1.2), whereas glutamate dehydrogenase (EC 1.4.1.3) is inhibited as HCO3- concentration is increased. The result is that flux through the entire glutamate-to-glucose pathway is inhibited by increasing HCO3- concentrations. A large proportion (more than 30%) of the glutamine removed undergoes complete oxidation. 3. In hepatocytes, and to a smaller extent in enterocytes, HCO3- is an accelerator of glutaminase. Synthesis of glucose and urea from glutamine in hepatocytes increases as HCO3- concentration is increased. Calculations show that fumarate, formed via aspartate aminotransferase and arginino-succinate lyase, is the precursor of the glucose. There is no complete oxidation of the carbon skeleton of glutamine in hepatocytes. 4. Leucine at near-physiological concentrations (0.1-1 mM) is an accelerator of glutaminase in hepatocytes, but not in kidney tubules or in enterocytes. 5. The results are discussed in relation to regulation of acid/base balance in vivo.
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PMID:A role for bicarbonate in the regulation of mammalian glutamine metabolism. 54 52

A chromatographic-videodensitometric assay was found to be appropriate for measuring the activity of glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, ornithine-2-oxoacid aminotransferase and histidine ammonia-lyase in human tissue homogenates. From the assay mixtures containing substrate(s), cofactor(s), buffer and tissue extract, five or ten microliters samples were taken at different time intervals and chromatographed on Dowex 50 X 8 type resin-coated chromatosheets. On each chromatoplate 50 nmoles of the amino acid to be measured were separately run as a reference for videodensitometric evaluation. By comparing the density of the reference amino acid to that of the individual samples the molar amount of amino acids formed or consumed in the reaction could be calculated. The present findings suggest that the chromatographic-videodensitometric microassay (CV-technique) is suitable for measuring the activity of amino acid transforming enzymes in minute amounts of tissue extracts.
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PMID:Determination of enzyme activity by chromatography and videodensitometry. I. Microassay of amino acid transforming enzymes in human tissue homogenates. 54 67

In rats, shortly after ligation of superior mesenteric artery serum enzyme activities are found significantly altered. Those changes concern aspartate aminotransferase (GOT), alanine aminotransferase (GPT), lipase, alpha amylase, and isocitrate dehydrogenase as well as glutamate dehydrogenase. The causes are discussed. The authors emphasize that the assessment of serum enzymes possibly gives some help in diagnosing acute intestinal ischemias in early stages.
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PMID:[Behavior of various serum enzymes following ligation of the superior mesenteric artery in the rat (preliminary report)]. 60 23

The hypothesis that mictochondrial damage is a significant factor in the pathogenesis of alcoholic liver disease (ALD) was investigated by enzymic analysis of mitochondrial fractions isolated from needle biopsy specimens from control patients, patients with fatty liver due to chronic alcoholism, and from patients with other forms of liver disease. Enzymes associated with the inner and outer mitochondrial membranes showed normal levels in ALD. Enzymes associated with the mitochondrial matrix, glutamate dehydrogenase, malate dehydrogenase and aspartate aminotransferase showed significantly raised levels in ALD, but the levels in patients with non-alcoholic liver disease was normal. In addition, analysis of the mitochondria by sucrose density gradient centrifugation revealed no differences between control tissue and liver from patients with alcoholic liver disease. These results do not indicate that there is significant mitochondrial damage in ALD. The raised mitochondrial matrix enzymes may represent an adaptive response to the ethanol load.
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PMID:Mitochondrial enzyme activities in liver biopsies from patients with alcoholic liver disease. 65 61

Previously, a proteolipid that can bind glutamate with high affinity has been isolated from pig heart mitochondrial membranes. A final affinity chromatography on gamma-methylglutamate-albumin coreticulated on glass fiber was necessary. This procedure includes long dialysis steps which tend to denature the high-glutamate affinity proteolipid. Here is described a new method of isolation which avoids long dialysis steps and yields greater amounts of the high-glutamate affinity proteolipid. The binding of glutamate or aspartate on high-glutamate affinity proteolipid has been studied by gel filtration, by equilibrium dialysis or by a new procedure of rapid centrifugation based on the insolubility of high-glutamate affinity proteolipid in water. The latter method permits the detection of low and high affinity sites for glutamate with a Kd 60 mM and 55 muM, respectively. Among a series of analogues, aspartate appeared to be the best competitor: Kd = 30 muM and two Ki values, 0.37 mM (at high glutamate concentration) and 3.8 muM (at low glutamate concentration). High-glutamate affinity proteolipid binds 0.4 nmol of glutamate but only 0.1 nmol of aspartate per mg protein. The sites for glutamate and aspartate appear to be different but interdependent. In the presence of high-glutamate affinity proteolipid, externally added glutamate stimulated the efflux of aspartate from preloaded liposomes. High-glutamate affinity proteolipid contains cardiolipin, phosphatidyl choline and phosphatidyl ethanolamine the distribution of which is different from that of the inner membrane. The effects of various phospholipases, trypsin, and thiol reagents were studied on the binding of glutamate. High-glutamate affinity proteolipid binds 9 nmol N-ethylmaleimide per mg protein but only 6.1 nmol in the presence of glutamate. The dissociation of high-glutamate affinity proteolipid caused by thiol reagents yielded a soluble protein fraction with higher affinity for glutamate. Electrophoresis and an immunological approach allowed the detection and titration of the glutamate dehydrogenase and aspartate aminotransferase present in high-glutamate affinity proteolipid in inhibited forms, the latter being 26-fold more concentrated than the former.
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PMID:Glutamate transport in pig heart mitochondria. Binding and structural properties of high-glutamate affinity proteolipid: reconstitution studies. 68 5

The method of progress curve analysis for enzyme-catalyzed reactions (Duggleby, R.G. and Morrison, J.F. (1977) Biochim. Biophys. acta 481, 297--312) has been extended to a two substrate, reversible reaction through the use of enzyme-catalyzed recycling of one of the products. The reaction investigated was that catalyzed by aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) and the product, alpha-ketoglutarate was recycled to glutamate using NADH and NH4Cl in the presence of glutamate dehydrogenase. The values determined for the kinetic parameters of the aminotransferase were found to agree well with those obtained from steady-state velocity measurements. The standard errors of the parameters, as calculated by the procedure originally described, were found to underestimate the observed variation between different experiments. Therefore, a procedure of data compression was devised which leads to more realistic values for standard errors. The compressed data obtained with aspartate aminotransferase have been fitted to the integrated rate equations that describe a variety of kinetic mechanisms. The best fit was obtained with the Ping-Pong model which is applicable to the aspartate aminotransferase reaction. Thus, progress curve analysis may be used to determine the kinetic mechanism of, and values of the kinetic parameters associated with, an enyzme-catalyzed reaction.
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PMID:Progress curve analysis in enzyme kinetics: model discrimination and parameter estimation. 71 44


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