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)

Cytosolic aspartate aminotransferase (c-AAT) was purified to homogeneity from porcine heart and immunized to rabbit for production of antiserum. The purity of this enzyme protein and the specificity of its antibody were judged by silver-stained-sodium dodecyl sulfate slab gel, Western blot transfer technique, and double immunodiffusion. The antibody against porcine heart c-AAT was found to cross-react with rat c-AAT but not with nine other different enzymes from the heart, liver, and muscle. Affinity purified antibody was used to localize this isoenzyme in the rat heart, liver, kidney, and cerebellum by indirect immunoperoxidase method. It was found that, in the rat heart muscle, c-AAT reaction product was present as a linear structure parallel to the muscle fiber and along the sarcolemma. Some cardiac muscle fibers contain more reaction products than the others. In the liver, reaction product was seen unevenly distributed in the hepatocytes. The Kupffer cells and endothelia were less stained. Most of the tubular epithelia of the loop of Henle in the kidney were intensely stained. But other tubular epithelia including convoluted and collecting tubules were sporadically and less stained. The basket and stellate cells and their neuronal processes and terminals in the cerebellum were markedly stained, but the Purkinje and granule cell bodies were weakly stained. For comparison of the staining intensity with enzyme activity in each organ, the c-AAT enzyme activity was simultaneously determined in those organs. This study indicates that the presence of c-AAT is specific in different organs and tissues.
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PMID:Production and characterization of an antibody to cytosolic aspartate aminotransferase and immunolocalization of the enzyme in rat organs. 640 65

General toxic and organotropic properties of sisomicin sulfate were studied in chronic experiments on different animal species with the use of doses equivalent to therapeutic ones in humans or exceeding them by several times. When sisomicin was injected intramuscularly for 4 weeks in a dose equivalent by the body surface to the average daily dose for humans, no significant effect on the macroorganism was observed. When the dose was 2--4 times higher, a significant increase in the blood serum levels of the urea nitrogen, creatinine, bilirubin and aspartate aminotransferase was shown. Histological examinations revealed focal adiposis of epithelial cells of the convoluted tubules of the kidney and small areas of parenchymal necrosis. Impairment of vestibular and auditory functions was detected in some animals.
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PMID:[General toxic and organotropic properties of sisomicin sulfate in chronic experiments on animals]. 660 12

Aspartate: 2-oxoglutarate aminotransferase [EC 2.6.1.1] was purified and crystallized from bakers' yeast. The crystalline preparation gave a single band on polyacrylamide disc gel electrophoresis in the presence of sodium dodecyl sulfate. However, in the absence of sodium dodecyl sulfate, the preparation gave one major band with two faint bands, all of which showed the same specific activity, molecular weight and serological properties. These faint bands appeared to be modified forms produced from the major band during the purification. The enzyme showed a molecular weight of 90,000 +/- 8,000 and 92,000 +/- 8,000 by gel filtration and sedimentation equilibrium analysis, respectively. The molecular weight of a subunit was estimated to be 45,000 by sodium dodecyl sulfate slab gel electrophoresis. Each subunit bound approximately 1 mol of pyridoxal 5'-phosphate. The bound pyridoxal 5'-phosphate showed an absorption maximum at 360 nm (epsilon M: 11,500) and 430 nm (epsilon M: 8,200) in alkaline and acidic conditions, respectively. Its proteolytic pK was pH 6.3. The enzyme showed an optimum pH of 8.0-9.0, and fairly high amino donor and acceptor specificities; aromatic amino acids and their corresponding 2-oxoacids were catalyzed at rates of 0.2-0.8% of those for aspartate and oxalacetate, respectively. Michaelis constants for various substrate were: L-aspartate (0.11 mM), L-glutamate (20.0 mM), oxalacetate (0.006 mM), and 2-oxoglutarate (0.16 mM). The antiserum against yeast aspartate aminotransferase did not form precipitin bands with homogeneous aspartate aminotransferases from pig heart cytosol, pig heart mitochondria or Escherichia coli B.
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PMID:Aspartate: 2-oxoglutarate aminotransferase from bakers' yeast: crystallization and characterization. 681 76

We found heterogenous ornithine oxoacid aminotransferase (L-ornithine: 2-oxo-acid aminotransferase, EC 2.6.1.1.3) in rat ascites hepatoma AH 130 cells. Compared with enzymes from normal rat tissues, this heterogenous enzyme showed larger Km values for 2-oxoglutarate, a different elution-profile upon affinity chromatography with 2-oxoglutarate, more anionic mobility upon polyacrylamide gell electrophoresis, and a clearly different salting-out property upon ammonium sulfate fractionation. Similar heterogeneity of this aminotransferase was found in human cancer cells.
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PMID:Ornithine oxoacid aminotransferase found in AH 130 ascites hepatoma cells. 705 19

In chicken embryo fibroblasts pulsed wih [35S]methionine, a precursor of mitochondrial aspartate aminotransferase with higher molecular weight (delta Mr approximately 3000) was detected by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Peptide mapping of the precursor and the mature enzyme confirmed their precursor-product relationship. No precursor of the homologous cytosolic isoenzyme was found. The precursor of the mitochondrial isoenzyme is synthesized on membrane-free polysomes in the cytosol (Sonderegger, P., Jaussi, R., Christen, P., and Gehring, H. (1982) J. Biol. Chem. 257, 3339-3345); its half-life is 30 to 60 s. The pronounced susceptibility of the precursor toward exogenous proteases contrasts the stability of the mature enzyme and thus indicates that the conformation or the quarternary structure of the protein must change concomitantly with its import into mitochondria. Administration of the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) to the cell cultures blocks the import of many matrix and inner membrane proteins into mitochondria. The precursor of mitochondrial aspartate aminotransferase is found to be accumulated in the cytosol. However, its steady state concentration in CCCP-treated cells exceeds the concentration in untreated cells by not more than 1 order of magnitude. During a chase, the radioactive precursor disappears with a half-life of approximately 5 with min without formation of mature enzyme. Thus, in CCCP-treated cells, a degradative process is limiting the accumulation of the precursor in the cytosol. When the chase is performed in the presence of cysteamine, an antagonist of CCCP, the precursor is processed to the mature enzyme. Newly synthesized cytosolic aspartate aminotransferase is not degraded.
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PMID:Biosynthesis and topogenesis of aspartate aminotransferase isoenzymes in chicken embryo fibroblasts. The precursor of the mitochondrial isoenzyme is either imported into mitochondria or degraded in the cytosol. 714 50

A fluorescent derivative of lysine-258 isolated from the active site of aspartate aminotransferase modified by treatment of the apoenzyme with pyridoxal 5'-sulfate has been characterized as a substituted 2H-pyrrolo[3,4-c]pyridine. Similar pyrrolopyridines are produced in up to 20% yield by reaction of pyridoxal sulfate with simple alkylamines or with amino acids including lysine. The latter forms two products, one of which is identical with that isolated from the enzyme. The pyrrolopyridine derived from ethylamine has been characterized by proton and 13C NMR, ultraviolet-visible, and mass spectroscopy and by its chemical reactions.
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PMID:Pyrrolopyridine derivatives from pyridoxal 5'-sulfate. 717 50

We studied the effects on 25 analytes of duration of contact of serum with non-anticoagulated blood and of temperature. Serum was separated after blood was allowed to stand, for 0, 2, 4, 6, 8, 24, or 48 h at 4, 23, or 30 degrees C. Results obtained for bilirubin, albumin, zinc sulfate turbidity, thymol turbidity, cholinesterase (EC 3.1.1.8), alkaline phosphatase (EC 3.1.3.1), leucine aminopeptidase (EC 3.4.11.1), amylase (EC 3.2.1.2), total cholesterol, triglycerides, beta-lipoprotein, serum urea nitrogen, creatinine, uric acid, and gamma-glutamyltransferase (EC 2.3.2.2) were not influenced by storage at 4, 24, or 30 degrees C for as long as 48 h. Negligible differences were seen for potassium in sera in contact with cells as long as 24 h at 23 degrees C and for inorganic phosphorus after 48 h at 4 degrees C. However, at 4 degrees C we noted an increase at 8 h, a slight decrease at 30 degrees C. Statistically significant changes were seen for total protein and calcium after 48 h at 30 degrees C; for aspartate aminotransferase (EC 2.6.1.1), and alanine aminotransferase (EC 2.6.1.2), between 8 and 24 h at 23 degrees C and as soon as 6 h at 30 degrees C; for lactate dehydrogenase (EC 1.1.1.27) after 8 h at 30 degrees C and between 8 and 24 h at 23 degrees C; for glucose at 24, 4, or 2 h of storage at 4, 23, or 30 degrees C, respectively; for inorganic phosphorus after 48 h at 23 degrees C or 8 h at 30 degrees C; for potassium after 4 h at 4 degrees C or 24 h at 30 degrees C; and for sodium after 48 h at 4 degrees C or 6 h at 23 or 30 degrees C.
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PMID:Serum-constituents analyses: effect of duration and temperature of storage of clotted blood. 744 20

To purify cytoplasmic and mitochondrial isoenzymes of aspartate aminotransferase (EC 2.6.1.1) from human liver. We used heat treatment, ammonium sulfate precipitation, anion- and cation-exchange chromatography, affinity chromatography, and isoelectric focusing. Final preparations of the isoenzymes were homogeneous, with specific activities of 198 and 208 kU/g for the cytoplasmic and the mitochondrial enzymes, respectively. The mitochondrial isoenzyme focused as a single band with a pl value of 9.60, whereas the cytoplasmic isoenzyme had subforms with pl values of 5.22, 5.42, and 5.62 at 4 degrees C. In Tris . HCl buffer, both isoenzymes have an activity maximum at pH 7.8. In [bis(2-hydroxyethyl)amino]tris(hydroxymethyl)methane (Bistris) buffer, however, the mitochondrial isoenzyme also showed an optimum pH of 6.7.
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PMID:Isolation and purification of aspartate aminotransferase isoenzymes from human liver by chromatography and isoelectric focusing. 746 Feb 73

J.M., a healthy, 25-year-old male, volunteered for a study involving warfarin and acetaminophen. Acetaminophen 1 g four times a day was started for 21 days. Liver function tests taken at regular intervals for the first 12 days were unremarkable. On day 18, however, aspartate aminotransferase (AST) was 527 IU/liter and alanine aminotransferase (ALT) was 166 IU/liter. Acetaminophen was discontinued and serum transaminase levels returned to baseline levels two weeks later (AST = 26, ALT = 20). Analysis of J.M.'s urine samples over the first 18 days showed excretion patterns of glucuronide, sulfate, and glutathione derived cysteine and mercapturic acid conjugates were similar to the other subjects in the study. Acetaminophen causes hepatotoxicity in overdose or malnourished or alcoholic patients, none of which applied to our subject. Differences in metabolic activation and capacity for glutathione synthesis can predispose individuals given therapeutic doses of acetaminophen to adverse effects. Failure to detoxify a highly reactive metabolite, formed by P-450 metabolism, via glutathione conjugation is responsible for the development of acute hepatic necrosis. Accumulation of the toxic metabolite due to depleted glutathione stores may have occurred with prolonged high dosing in our subject and been responsible for his abnormal rise in liver enzymes.
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PMID:Abnormal serum transaminases following therapeutic doses of acetaminophen in the absence of known risk factors. 755 49

In vitro techniques make a major contribution to the development of alternatives to the in vivo "Draize" skin irritation test, and the development of sensitive and generally applicable in vitro endpoints of cutaneous toxicity is an area of intensive research. To investigate in vitro characteristics of cutaneous irritation, skin explants of rabbit and human origin were topically exposed to chemical irritants, after which the culture medium was analyzed for the presence of metabolites of both arachidonic and linoleic acid. In rabbits exposed to the potent irritant benzalkonium chloride, a direct relation was established between clinical signs of irritation and in vitro release of the proinflammatory mediator 12-hydroxyeicosatetraenoic acid (12-HETE) by the exposed skin. Histological examination revealed varying degrees of epidermal damage. 12-HETE was also the predominant hydroxy fatty acid released in a dose-dependent way by rabbit skin cultures after in vitro exposure to sodium dodecyl sulfate (SDS), benzalkonium chloride (BC), and formaldehyde (FA). Human skin cultures released, in addition to 12-HETE, predominantly 15-HETE and 13-hydroxyoctadecadienoic acid (13-HODE), omega-6 oxygenase products of arachidonic acid and linoleic acid, respectively. The irritant-induced release of hydroxy fatty acids was strongly inhibited by the lipoxygenase inhibitor eicosatetraynoic acid, indicating enzyme-mediated generation of these bioactive lipids. Comparison of hydroxy fatty acid release to more established markers of cytotoxicity (leakage of the cellular enzymes, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH)) revealed that increased levels of 13-HODE, 9-HODE, 12-HETE, and ALT were specific markers of cutaneous irritancy in rabbit skin cultures.
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PMID:Release of arachidonic and linoleic acid metabolites in skin organ cultures as characteristics of in vitro skin irritancy. 760 24


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