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)

Aspartate aminotransferase (EC 2.6.1.1) activity and the distribution of its isoenzymes in human liver were examined. Rabbit antiserum against porcin soluble (i.e., non-mitochondrial) enzyme cross-reacted with the soluble enzyme of human origin and was used in an immunoprecipitation assay to quantitate the soluble and mitochondrial isoenzymes. These were separated by rapid, semiquantitative electrophoresis on cellulose acetate and by three other quantitative techniques: isoelectric focusing and anion-and cation-exchange chromatography. The mitochrondrial enzyme averaged 81% of the total activity in normal adult human liver (n = 4). Its contribution was dramatically reduced in single specimens of human fetal liver (56% of total activity) and hepatoblastoma tissue (38%). Total enzyme activities (mumol min-1 per gram of tissue) were: adult, 150; fetal, 38; tumor, 6. Total enzyme concentrations (micromoles of enzyme per kilogram of tissue) found were: adult, 10.8; fetal, 2.7; tumor, 0.4. The concentrations and isoenzyme distribution in human liver are compared to those in various animal model systems. Other methods for quantitative estimation of the isoenzymes and their adaptability for use in estimating concentrations in serum are reviewed.
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PMID:Aspartate aminotransferase activity and isoenzyme proportions in human liver tissues. 21 6

Aspartate aminotransferase in the sera of normal subjects and of patients with hepatic diseases has been immunologically separated into two isoenzymes, cytosolic aspartate aminotransferase and mitochondrial aspartate aminotransferase. The activity of the isoenzymes was measured in three different buffer solutions with or without pyridoxal 5'-phosphate. To attain maximal activation, the apoenzyme of mitochondrial fraction must be preincubated with pyridoxal 5'-phosphate longer than that of the cytosolic fraction in either of the three reaction mixtures. In most sera the activity of both isoenzymes increased substantially in the presence of pyridoxal 5'-phosphate regardless of the type of buffer solutions. Both the apoenzymatic activity and the ratio of apo- to holo-enzymatic activity of each of the isoenzymes varied among samples from the patients with hepatic diseases. However, significantly high ratios of apo- to holo-enzymatic activity of both isoenzymes were observed in the patients with hepatoma in contrast with those with other hepatic diseases. These findings suggest that the simultaneous measurement of both apo- and holo-enzyme activities of aspartate aminotransferase isoenzymes may be useful in the clinical assessment of hepatic diseases.
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PMID:Apoenzyme of aspartate aminotransferase isozymes in serum and its diagnostic usefullness for hepatic diseases. 22 64

Aspartate aminotransferase (L-aspartate : 2-oxoglutarate aminotransferase, EC 2.6.1.1) has been covalently bound to chemically activated collagen films. This enzyme had never previously been coupled to any other solid support. The coupling method, including acyl azide formation on the carrier, allowed coupling of many other enzymes. A systematic study of coupling conditions has been performed; influence of time of coupling and of concentration of coupling solution on the enzymatic activity retained on the film. Coupling solutions could be used for several successive couplings. To determine the yield of binding, N-[14C] ethylmaleimide-labelled enzyme was prepared fully active and bound to collagen films. After lyophilisation the film retained most of its activity when stored in buffer and the half-life of the enzymatic film was about ten months. pH Dependence and activation energy were about the same for soluble and coupled enzyme. Coupling protects against thermal denaturation and increases the stability of the enzyme; the enzymatic film could be used repeatedly. Kinetics were somewhat modified in the coupled enzyme as compared to the enzyme in solution. Glutamate appeared more available while oxaloacetate seemed to be limiting. These modifications might be due to the proteic support itself. The enzymatic films also revealed themselves as a good tool for industrial or clinical purposes as well as for studying the mechanism of enzyme action.
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PMID:Surface-bound aspartate aminotransferase on collagen films. Compared properties with native enzyme. 23 97

Blood serum of pygmy goats (both sexes, and castrated males) was analyzed to establish biochemical reference values. Influence of age on reference values was also studied. Serum biochemical analyses were made for urea nitrogen, creatinin, bilirubin, lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, glucose, uric acid, and total lipids. These serum values for pygmy goats were similar to those reported for man, except as follows: Aspartate aminotransferase activities were slightly higher than those reported for man. Glucose concentrations in pygmy goats were slightly lower than in human beings, and uric acid levels were significantly lower than the values for man. Female and castrated male goats had lower total lipid concentrations than did human beings, whereas intact males had higher concentrations. Thus, of the 9 measured variables for pygmy goats, 5 were comparable to human values. This, together with other attributes, including the small size which conduces to economics of maintenance and enhances the desirability of using pygmy goats in research.
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PMID:Serum biochemistry values in normal pygmy goats. 59 8

Aspartate aminotransferase activity was measured in plasma, in liver and in heart mitochondrial and cytoplasmic preparations from rats immediately after death and after a post-mortem interval of 15 h. No significant stimulation of activity on addition of pyridoxal 5-phosphate to the assay medium could be demonstrated in any preparations obtained immediately after death. Significant stimulation occurred in both cytoplasmic and mitochondrial preparations of liver and myocardium after a 15-h post-mortem interval, but not in plasma stored for the same period. It appears, therefore, that variations in the intracellular saturation of apoenzyme with coenzyme cannot account for the observed differences in activation of aspartate aminotransferase by pyridoxal 5-phosphate in sera from patients with myocardial infarction and liver disease. Changes in degree of saturation of apoenzyme seem to occur intracellularly after cell death or injury and before release into the circulation.
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PMID:The changes in activation of intracellular aspartate aminotransferase by pyridoxal 5-phosphate after cell death. 63 4

The activities of alkaline phosphatase, aspartate aminotransferase and creatine kinase in sera of 1,033 children and adolescents aged 5 to 20 years were measured. The results showed significant deviation from the gaussian distribution. Because of differences between sexes and nonlinear relationship to age, sex- and age-related values for the 95th, 90th, and 5th percentiles are presented. Alkaline phosphatase activity increased markedly between 5 and 14 years of age in male subjects and 5 and 12 years of age in female subjects. The peak at puberty was more pronounced in boys than in girls. After puberty, activities decreased toward adult values. Aspartate aminotransferase activity showed a gradual significant decrease between 5 and 17 years of age in male subjects and 5 and 16 years of age in female subjects; then it remained steady until 20 years of age. Creatine kinase activity remained constant in male subjects between 5 and 12 years old, then rose to a maximum at 15 to 16 years of age before declining rapidly toward adult values. In female subjects, creatine kinase activity remained stable from 5 to 12 years of age, then decreased gradually in early adulthood.
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PMID:Age dependence of serum enzymatic activities (alkaline phosphatase, aspartate aminotransferase, and creatine kinase) in healthy children and adolescents. 71 84

Aspartate aminotransferase (EC 2.6.1.1) activities in sera from nine healthy individuals were monitored during two weeks, both with and without first supplementing the serum with pyridoxal phosphate. Pyridoxal phosphate supplementation caused a mean increase of 39% (range, 33-55%) in measured activity. The biological variability during the two-week period was independent of pyridoxal phosphate supplemantation. The intra-individual variability (CV) was 5.3% and 5.1% with and without pyridoxal phosphate supplementation, respectively; the corresponding inter-individual variability was 13.2% and 13.6%. We conclude that the reference interval will be insensitive to intra-individual fluctuations in aspartate aminotransferase activity in serum, whether or not the serum is supplemented with pyridoxal phosphate.
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PMID:Biological variability in aspartate aminotransferase activity in serum of healthy persons, and effect of in vitro supplemantation with pyridoxal 5-phosphate. 83 43

I evaluated the diagnostic value of routinely ordered liver-function tests in 175 biopsy-proven cases of hepatic disease by use of stepwise discriminant analysis. The tests studied-total and "direct" bilirubin, alkaline phosphatase, lactate dehydrogenase, and aspartate aminotransferase-correctly classified 45-73% of cases, depending on the homogeneity of the diagnostic groups. Aspartate aminotransferase and alkaline phosphatase were the best discriminators. When all tests were used in the most homogeneous groups (tumors, cirrhosis, and hepatitis), there was a stepwise improvement in diagnostic accuracy from 51 to 73%.
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PMID:Diagnostic effectiveness of biochemical liver-function tests, as evaluated by discriminant function analysis. 84 56

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

Aspartate aminotransferase was detected in the adrenals of 6-7-week human embryos, the activity being the highest at the 7-9th and 12-14th weeks. Alanine aminotransferase was found in 15-week foetuses. During all the period investigated (6-28 weeks), the activity of aspartate aminotransferase was found to be higher than that of the second enzyme. The activity of both enzymes is higher in female foetuses than in male ones. However, age changes in the activity of both enzymes in male embryos and foetuses were of the same sign as in female ones.
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PMID:[Aspartate and alanine aminotransferase activity in the adrenal cortex of human embryos and fetuses]. 94 57


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