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)

The response of various species of Anser and Branta geese and other avian species to the ingestion of carbophenothion (S-[[(4-chlorophenyl)thio]methyl] O,O-diethyl phosphorodithioate) has been investigated. Optimum assay conditions for measurement of glutamate oxaloacetate transaminase, glutamate dehydrogenase, sorbitol dehydrogenase, and cholinesterase in avian plasma were developed for the study. The administration of acutely toxic doses of carbophenothion to Japanese quail, pigeons, and chickens, and to Greylag, Pink-footed, Greenland White-fronted, and Canada geese led to species-dependent responses for both plasma glutamate oxaloacetate transaminase and cholinesterase levels. Carbophenothion administered to Japanese quail at several dose levels produced changes in plasma enzyme levels which were dependent on dose and time. The level of plasma glutamate oxaloacetate transaminase after dosing in the Anser family of geese rose more rapidly than in the Branta species but no change was found in this enzyme in either chickens or pigeons. In contrast to geese and pigeons, chickens exhibited no plasma cholinesterase inhibition for 3 hr after dosing. These enzyme changes demonstrate a species variation in the toxicological response of birds to a pesticide and indicate the desirability of using more than one avian species for pesticide toxicity testing.
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PMID:Variation in the response of plasma enzyme activities in avian species dosed with carbophenothion. 72 17

The method for the determination of enzymic activity in turbid, lipaemic sera, which involves clearing by polyanion precipitation with heparin and magnesium chloride, was critically reviewed. In the diagnosis of diseases of the liver and pancreas, which are frequently associated with hyperlipoproteinaemia, only residual enzyme activities are measured in the cleared serum after polyanion treatment. In the measurement of glutamate dehydrogenase and in the Phadebas test for alpha-amylase, the enzymes are inactivated by treatment with heparin and magnesium chloride. On the other hand, as a result of polyanion precipitation gamma-glutamyl transferase is transferred, together with lipoproteins and chylomicrons, to the lipid-rich supernatant. Acid phosphatase also exhibits only residual activity in cleared serum. The activity of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, leucine arylamidase, cholinesterase, creatine kinase, lactate dehydrogenase, and alpha-hydroxybutyrate dehydrogenase, and the activity of alpha-amylase in the Merckotest are not affected by polyanion treatment of the serum.
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PMID:[Enzyme diagnosis in lipaemic sera before and after polyanion precipitation with heparin and magnesium chloride (author's transl)]. 92 35

The rate of distribution of cell enzymes between the intravascular and extravascular space was studied, following a sudden decrease of enzyme activities in plasma. This rapid decrease of enzyme activities was achieved in rats by a rapid exchange of the blood with a twofold volume of a suspension of homologous erythrocytes in isoosmolar bovine serum albumin solution. After this plasmapheresis, the activities of seven cell enzymes in the plasma were decreased to 14 to 22% of their original values. The subsequent increase in activities showed different kinetics, depending on the enzyme. After 120 min, creatine kinase had reached the starting activity; malate dehydrogenase and aldolase reached their original activities after 180 min. Aspartate aminotransferase, glutamate dehydrogenase, alanine aminotransferase and pyruvate kinase increased more slowly and they had still not reached their starting values after 240 min. Repetition of the plasmapheresis after 90 min had no obvious effect on the kinetics of the subsequent activity increase. During the first minutes after plasmapheresis the adjustment of the activity equilibrium between the interstitial and the intravascular compartments depends mainly on the capillary permeability. It is therefore possible to determine half-life constants for the distribution of enzymes within the extracellular space. The constants for malate dehydrogenase and aldolase are almost identical with those determined by intravenous injection, whereas there are discrepancies in the constants for the remaining enzymes. The constants for pyruvate kinase and glutamate dehydrogenase are significantly lower, while those for aspartate aminotransferase, alanine aminotransferase and creatine kinase are significantly higher, than those determined after intravenous injection. Possible reasons for these differences are disucssed.
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PMID:[Plasmapheresis as an experimental model for studies on the extracellular distribution of enzymes. Distribution and transport of cell enzymes within the extracellular space. IV (author's transl)]. 93 47

Because of the difficulties in drawing blood for clinical chemistry in small laboratory animals there exist many methods for sampling blood and the preparation of serum, none of which is generally accepted or well standardised. It was the aim of this study to investigate the effects of sampling techniques on normal values of enzyme activities in the serum of rat and mouse. The activities of the following enzymes were determined: sorbitol dehydrogenase, lactate dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, pyruvate kinase, creatine kinase, myokinase, alkaline phosphatase and leucine aminopeptidase. In addition plasmaproteins, urea and inorganic phosphorus were measured. In rats blood was obtained from the following sites: retroorbital venous plexus, jugular vein, heart and ventral aorta. In mice blood was sampled from the jugular vein and the ventral aorta. Shifts of water from the interstitial to the intravascular space due to hypovolemia occurring during the experimental procedure were followed up by measuring the hematocrit and the distribution of radioiodide labelled albumin. In rats the activities of lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase, pyruvate kinase, creatine kinase and myokinase found in blood serum obtained from the retroorbital venous plexus and the ventral aorta were too high compared to the other sampling sites. Activities of alkaline phosphatase and alanine aminotransferase were slightly elevated when blood was sampled from the punctured retroorbital venous plexus. Small differences in plasmaproteins and hematocrit values were found to be due to acute shifts of water within the extracellular space. In mice the activities of lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and myokinase were found to be too high in blood serum obtained from the ventral aorta. Efflux of enzymes from damaged cells and the interstitial space ive caused erroneous results too, but only to a minor extent. The most reliable method for blood sampling in rat and mouse is the cannulation of the jugular vein. The heart puncture can be recommended too. Attention should be paid, however, to the possibility of aspirating disrupted muscle cells through the inserted needle.
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PMID:[Effects of blood sampling on enzyme activities in the serum of small laboratory animals (author's transl)]. 108 84

Sources of variation in assays of aspartate aminotransferase (EC 2.6.1.1) activity were examined in an interlaboratory survey and through an examination of materials used as calibration materials in these assays. Four highly stable lyophilized specimens containing human cytoplasmic enzyme, with activities of 0, 22, 46, and 96 U/liter at 30 degrees C and optimal substrate concentrations, were assayed by 319 laboratories. Mean values obtained on these specimens by laboratories using 2,4-dinitrophenylhydrazine kits varied among manufacturers and deviated from values expected from this procedure. The average coefficient of variation (CV) with these kits was greater than 20%. Automated continuous-flow procedures with use of diazonium salt showed the best precision (av CV, less than 10%). However, the automated continuous-flow malate dehydrogenase/NADH coupled method produced an average CV greater than 20%. Results from each of the automated methods were related to a reference malate dehydrogenase/NADH coupled continuous kinetic assay method by temperature relationships alone. Mean values from manual diazonium salt procedures were 1.7-fold greater than similar reference values (av CV was 18%). The higher results were attributed to the use of poorly-defined units and to an artifact caused by chromophore stabilizers in this procedure when aqueous samples are used. The average CV in continuous kinetic methods varied among kit manufacturers, ranging from 6 to 28% for the specimen of highest activity. Variations in results were much larger at 366 nm than at 340 nm than at 340ity. Variations in results were much larger at 366 nm than at 340 nm. Interassay relationships of these methods are presented. Concentrations of pyruvate in commercially available calibration materials differed between manufacturers, varied in stability, and deviated from the expected concentration. For some colorimetric assays the precision attained on reported absorbance values for the enzyme specimens was of the same order of magnitude as that for pyruvate standards. Other sources of error are revealed by the interlaboratory survey. The value of commercially available sources of enzyme activity as calibration or control materials was assessed by evaluating the following properties: activity at suboptimal concentrations of L-aspartate or 2-oxoglutarate, temperature effects, preincubation lability owing to aspartate and phosphate, pyridoxal phosphate saturation, contamination with glutamate dehydrogenase, and manufacturer's rated activity. These properties are compared to those of human cytoplasmic enzyme in a human serum matrix.
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PMID:Interlaboratory proficiency, intermethod comparison, and calibrator suitability in assay of serum aspartate aminotransferase activity. 113 21

The realtionship between growth rate and the metabolic activity of certain liver enzymes was studied using two strains of White Plymouth Rock chickens which had been selected in divergent directions for eight-week body weight. The activities of hexokinase, glucokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, citrate synthase, glycogen synthetase, glutamate dehydrogenase and aspartate transaminase were measured at 4, 8 and 20 weeks of age. The mean percentage rate of growth of the birds selected for high eight-week body weight exceeded that of the birds selected for low eight-week body weight only during the early growth period. Thereafter, and until sexual maturity, the low-line birds grew at a faster rate, relative to body size. The mature body weight of the high-line birds exceeded that of the low-line birds by a factor of approximately 1.5. A close similarity was noted between the metabolic activity of certain liver enzymes and the growth rate (relative to body size) of the birds studied. At four and eight weeks of age, the faster-growing birds (whether high- or low-line) generally exhibited a greater capacity for glucose phosphorylation and glycolysis, but a poorer capacity for glycogen synthesis, than the slower-growing birds. At twenty weeks, growth rate and metabolic activity were similar in both strains.
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PMID:Activity of certain liver enzymes in fast- and slow-growing lines of chickens. 118 17

Isolated mitochondria of pigeon and guinea pig liver were subjected to zonal centrifugation. With pigeon liver mitochondria there was uniform distribution of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, aspartate aminotransferase and glutamate dehydrogenase activities. Guinea pig liver mitochondria demonstrated two pyruvate carboxylase and phosphoenolpyruvate carboxykinase maxima but only one maximum with aspartate aminotransferase, malate dehydrogenase and glutamate dehydrogenase. Mitochondrial enzyme levels in rat, pigeon and guinea pig indicate different roles of certain gluconeogenic enzymes in the transport of carbon and hydrogen in and out of mitochondria.
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PMID:The relationship between mitochondrial heterogeneity and gluconeogenesis in liver mitochondria of the rat, pigeon and guinea pig. 119 37

Ammonium sulfate fractionation of proteins from extremely halophilic bacteria on Sepharose 4B, carboxymethylcellulose, diethylaminoethylcellulose, and hexamethylenediamine-Agarose is described. Halophilic proteins are absorbed on these gels at 2.5 M ammonium sulfate and eluted by decreasing concentration gradients of this salt. The method has enabled the separation of malate dehydrogenase from glutamate dehydrogenase and aspartate aminotransferase on Sepharose 4B and the additional 15-fold purification of glutamate dehydrogenase on DEAE-cellulose. The technique is simple and convenient, operates at low cost, and possesses great power of resolution. The mechanism of adsorption is discussed and compared to previous instances of "hydrophobic chromatography". It is concluded that the retention of halophilic proteins on the polysaccharide gels at 2.5 M ammonium sulfate is due to hydrophobic interactions.
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PMID:Hydrophobic chromatography and fractionation of enzymes from extremely halophilic bacteria using decreasing concentration gradients of ammonium sulfate. 127 45

Glutamate metabolism in rat cortical astrocyte cultures was studied to evaluate the relative rates of flux of glutamate carbon through oxidative pathways and through glutamine synthetase (GS). Rates of 14CO2 production from [1-14C]glutamate were determined, as was the metabolic fate of [14C(U)]glutamate in the presence and absence of the transaminase inhibitor aminooxyacetic acid and of methionine sulfoximine, an irreversible inhibitor of GS. The effects of subculturing and dibutyryl cyclic AMP treatment of astrocytes on these parameters were also examined. The vast majority of exogenously added glutamate was converted to glutamine and exported into the extracellular medium. Inhibition of GS led to a sustained and greatly elevated intracellular glutamate level, thereby demonstrating the predominance of this pathway in the astrocytic metabolism of glutamate. Nevertheless, there was some glutamate oxidation in the astrocyte culture, as evidenced by aspartate production and labeling of intracellular aspartate pools. Inhibition of aspartate aminotransferase caused a greater than 70% decrease in 14CO2 production from [1-14C]glutamate. Inhibition of GS caused an increase in aspartate production. It is concluded that transamination of glutamate rather than oxidative deamination catalyzed by glutamate dehydrogenase is the first step in the entry of glutamate carbon into the citric acid cycle in cultured astrocytes. This scheme of glutamate metabolism was not qualitatively altered by subculturing or by treatment of the cultures with dibutyryl cyclic AMP.
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PMID:Glutamate metabolism in rat cortical astrocyte cultures. 134 25

The level of aspartate aminotransferase in liver mitochondria was found to be approximately 140 microM, or 2-3 orders of magnitude higher than its dissociation constant in complexes with the inner mitochondrial membrane and the high molecular weight enzymes (M(r) = 1.6 x 10(5) to 2.7 x 10(6)) carbamyl-phosphate synthase I, glutamate dehydrogenase, and the alpha-ketoglutarate dehydrogenase complex. The total concentration of aminotransferase-binding sites on these structures in liver mitochondria was more than sufficient to accommodate all of the aminotransferase. Therefore, in liver mitochondria, the aminotransferase could be associated with the inner mitochondrial membrane and/or these high molecular weight enzymes. The aminotransferase in these hetero-enzyme complexes could be supplied with oxalacetate because binding of aminotransferase to the high molecular weight enzymes can enhance binding of malate dehydrogenase, and binding of both malate dehydrogenase and the aminotransferase facilitated binding of fumarase. The level of malate dehydrogenase was found to be so high (140 microM) in liver mitochondria, compared with that of citrate synthase (25 microM) and the pyruvate dehydrogenase complex (0.3 microM), that there would also be a sufficient supply of oxalacetate to citrate synthase-pyruvate dehydrogenase.
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PMID:Glutamate-malate metabolism in liver mitochondria. A model constructed on the basis of mitochondrial levels of enzymes, specificity, dissociation constants, and stoichiometry of hetero-enzyme complexes. 135 Feb 79


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