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 aromatic amino acid aminotransferase was purified to a homogenous state from a gramicidin S-producing strain of Bacillus brevis. The enzyme shows a molecular weight of about 71,000 on gel-filtration. The subunit molecular weight is about 35,000 as determined by sodium dodecyl sulfate gel electrophoresis, indicating that the enzyme is a dimer. The enzyme exhibits absorption maxima near 425 and 330 nm at neutral pH. One mole of pyridoxal phosphate is bound per subunit. The enzyme has amino donor specificity for aromatic amino acids, L-phenylalanine, L-tyrosine, and L-tryptophan, and utilizes 2-oxoglutarate as the amino acceptor. This enzyme activity was separated from both the aspartate aminotransferase activity and the branched chain amino acid aminotransferase activity by chromatography on DEAE-Sephadex.
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PMID:Purification and properties of the aromatic amino acid aminotransferase from gramicidin S-producing Bacillus brevis. 244 Aug 56

The intracellular proportion of the pyridoxal 5'-phosphate form of aspartate aminotransferase to the total enzyme in E. coli B cells was determined by a newly devised method, dependent on selective inactivation of the intracellular pyridoxal 5'-phosphate form of the enzyme by extracellularly added sodium borohydride. A large portion (80-99%) of the intracellular aspartate aminotransferase was in pyridoxal 5'-phosphate form in both natural and synthetic medium-grown bacterial cells. The intracellular predominancy of pyridoxal 5'-phosphate did not vary during the growth of bacteria and during incubation of bacterial cells in various kinds of buffers with different pH values. In contrast, the saturation levels generally used to describe in vivo the proportions of the apo and holo vitamin B6-dependent enzymes did not reflect the intracellular amount of the pyridoxal 5'-phosphate (holo) form of aspartate aminotransferase probably because the intracellular pyridoxal 5'-phosphate form was changed to an apo form by the disruption of bacterial cells for preparing crude extract. Various extracellularly-added vitamin B6 antagonists decreased the intracellular amount of pyridoxal 5'-phosphate without decrease in the total intracellular activity of the enzyme. The modified forms were stable in E. coli B cells and reversed into pyridoxal 5'-phosphate form by incubation of the antagonist-treated cells in the buffer containing pyridoxal. The present results showed that the sodium borohydride reduction method can be used for further analysis of the in vivo interaction of pyridoxal 5'-phosphate and apoaspartate aminotransferase. The fact that about 50% of the intracellular pyridoxal 5'-phosphate form was changed to a modified form without impairment of cell growth in the presence of 4-deoxypyridoxine, and that about 50% of intracellular modified aspartate aminotransferase was reversed to pyridoxal 5'-phosphate by the removal of antagonist followed by incubation suggested that there exists characteristically 2 different fractions of pyridoxal 5'-phosphate forms of aspartate aminotransferase in E. coli cells.
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PMID:Intracellular predominance of the pyridoxal 5'-phosphate form of aspartate aminotransferase in Escherichia coli B and reversible transformation of this form by extracellular substances. 250 48

The authors studied the pharmacotherapeutic efficacy of antioxidants vitamin E, sodium selenite, and their combination in damage to rat liver by CCl4 and the anthelmintic agent chloxyl. Changes of the intensity of peroxidation of biological membrane lipids, the activity of enzymes-markers of hepatocyte cytolysis--alanine aminotransferase and aspartate aminotransferase--in blood serum, and changes in the structure of the liver were studied. Antioxidants and their combination blocked lipid peroxidation, reduced the activity of alanine aminotransferase and aspartate aminotransferase in blood serum considerably, and caused a protective effect on the structure of rat liver in its damage by CCl4 and chloxyl.
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PMID:[Experimental antioxidant therapy in toxic liver damage from CCl4 and chloxyl]. 255 82

The primary structure of tyrosine aminotransferase, as deduced from the nucleotide sequence of complementary DNA, was confirmed by fast atom bombardment mass spectrometry of tryptic peptides derived from the purified protein. Limited digestion of the native enzyme with trypsin released an acetylated, amino-terminal peptide; the new amino terminus in the modified enzyme was Val65. Endogenous proteases generated a chromatographically separable form of tyrosine aminotransferase that began at Lys35. Neither trypsin nor the other proteases altered the catalytic activity of tyrosine aminotransferase. Reduction of the holoenzyme with sodium borohydride yielded a major tryptic peptide containing phosphopyridoxamine bound to lysine 280, which probably functions in transamination. The carboxyl terminus of tyrosine aminotransferase contains features that typify proteins with short half-lives; it includes two negatively charged, hydrophilic segments that are enriched for glutamyl residues and are similar to a PEST region in ornithine decarboxylase (Rogers, S., Wells, R., and Rechsteiner, M. (1986) Science 234, 364-368). Tyrosine aminotransferase belongs to a superfamily of enzymes which includes aspartate aminotransferase and can be aligned so that many invariant, functional residues coincide. Like the isoenzymes of aspartate aminotransferase, tyrosine aminotransferase may contain two domains, with a central, catalytic core, and a small domain made up of both amino- and carboxyl-terminal components. We speculate that the exposed small domain may confer the unusually rapid degradative rate that characterizes this enzyme.
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PMID:The structure of tyrosine aminotransferase. Evidence for domains involved in catalysis and enzyme turnover. 256 40

A study is presented in which eight healthy male non-smoking volunteers ingested a daily amount of 0.5 mg/kg butylated hydroxyanisole (BHA) for 10 consecutive days. Blood samples were taken on days -6 and 0 before and on days 4 and 7 after the first BHA administration for the assessment of standard clinical plasma parameters (L-aspartate aminotransferase, L-alanine-aminotransferase, L-gamma-glutamyltranspeptidase, creatine phosphokinase, lactate dehydrogenase, total protein, albumin, urea, creatinine, Na+, and Cl-). Antipyrine (500 mg p.o.) and paracetamol (500 mg p.o) were administered before and during BHA administration as test substances to measure phase-I and phase-II biotransformation capacity. Saliva samples and urine were subsequently collected for the assessment of kinetic parameters (e.g. saliva elimination half-life, saliva clearance, apparent volume of distribution) and urinary excretion of metabolites. Kinetic plasma parameters of BHA itself were determined in plasma samples obtained via a catheter in an arm vein after oral BHA intake on days 0 and 7. Levels of antipyrine, paracetamol, BHA and metabolites in plasma, saliva or urine were quantified by standard or newly developed reversed-phase high-performance liquid chromatography methods. Urinary excretion of Na+, K+, and Cl-, as well as osmolality of urine were measured on three days before and six days during BHA administration. Generally, no significant differences were detected in the parameters measured, indicating that oral administration of BHA to men for 10 days remains without effects on clinical biochemical parameters and phase-I and phase-II biotransformation capacity. In contrast, urinary excretion of metabolites of BHA was significantly increased on days 3 and 7 vs. the first day of BHA administration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of subacute oral intake of the food antioxidant butylated hydroxyanisole on clinical parameters and phase-I and -II biotransformation capacity in man. 259 85

We determined the effect of long-term freezer storage and repeated thawing and freezing of serum on concentrations of electrolytes (sodium, potassium, calcium, and phosphate), enzymes (aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, and creatine kinase), total protein, tumor markers (carcinoembryonic antigen and alpha-fetoprotein), and other substances. Vials (1 ml) of frozen serum from a single blood drawing from 40 women with no breast disease and 70 with benign breast disease were analyzed annually from 1983 to 1987. Blood had been obtained from 40 subjects in 1978, 40 in 1980, and 30 in 1983. Thawing and refreezing studies were done in two ways: (1) serum samples from 30 subjects with benign breast disease were thawed at weekly intervals for 6 weeks and (2) serum samples from 30 patients with stage IV breast cancer were analyzed for alpha-fetoprotein and carcinoembryonic antigen, and serum specimens from 23 patients with benign breast disease and 7 control subjects were analyzed for lactate dehydrogenase and creatine kinase after thawing and keeping the samples at room temperature for up to 4 hours and then refreezing them. For measuring laboratory variability, duplicate samples were processed. Long-term storage (up to 10 years) and repeated thawing and refreezing did not affect the results of any tested constituents of serum. Although most measurements showed statistically significant variability over test cycles, these differences were thought to be due to laboratory variability.
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PMID:Effect of long-term freezer storage, thawing, and refreezing on selected constituents of serum. 259 13

Thirty female beagle dogs, 7 to 8 months old, were assigned to five groups. Control, low dosage, medium dosage, high dosage, and pair-fed groups were offered 0, 1, 2, 4 and 0 mg of sodium arsenite per killigram of body weight per day (mg/kg/day), respectively, in their feed. On Day 59, the dosage was doubled for the rest of the experiment, which ended on Day 183. Nominal dosages of 4 and 8 mg/kg/day caused a significant decrease in feed consumption. The initial decreased feed consumption was followed by increased intake over time. Nominal dosages of 4 and 8 mg/kg/day caused a significant decrease in body weight. Body weight loss of high dosage and pair fed groups were not significantly different. Serum aspartate aminotransferase was elevated in dogs exposed to 4 and 8 mg/kg/day of sodium arsenite. Serum alanine aminotransferase was elevated in dogs exposed to 2, 4, and 8 mg/kg/day. No gross or light microscopic lesions were present in the liver of any group. This study shows that dietary sodium arsenite causes a dose-dependent decrease of feed consumption and body weight. Weight loss is caused by decreased feed consumption, not by the direct effect of the sodium arsenite.
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PMID:Effect of subacute low level dietary sodium arsenite on dogs. 261 77

Rats were fed for 23 d diets adequate or deficient in vitamin B-6 and containing selenium as either sodium selenite, selenocysteine (SeCys) or selenomethionine (SeMet). They were then injected with 75Se of the same chemical form and killed 2 d later. Tissue deposition of stable and radiotracer selenium and the activity of glutathione peroxidase (GSHPx) were used to assess selenium utilization. Erythrocyte levels of selenium and GSHPx were lower in vitamin B-6--deficient animals for all forms of selenium; however, 75Se deposition in erythrocytes was not affected by vitamin B-6 status. The activities of cystathionine lyase, aspartate aminotransferase and selenocysteine lyase were lower in livers of vitamin B-6--deficient rats than in vitamin B-6--supplemented rats. The proportion of liver and kidney 75Se soluble in 5% trichloroacetic acid and 0.1 M 2-mercaptoethanol was consistently lower in vitamin B-6--deficient animals, but cation-exchange chromatography of tissue extracts did not identify a specific low-molecular-weight species. Tissue retention of 75Se provided as SeMet was increased in vitamin B-6--deficient animals, but the proportion of 75Se retained in muscle and liver as SeCys was significantly reduced. These findings suggest that the conversion of SeMet to a form available for GSHPx synthesis is reduced by vitamin B-6 deficiency.
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PMID:Effects of vitamin B-6 deficiency on selenium metabolism in the rat. 262 89

The precursor to rat liver mitochondrial aspartate aminotransferase has been expressed in Escherichia coli JM105 using the pKK233-2 expression vector. This mammalian natural precursor has been isolated as a soluble dimeric protein. The amino-terminal sequence and the amino acid composition of the isolated protein correspond to those predicted from the inserted cDNA (Mattingly, J. R., Jr., Rodriguez-Berrocal, F. J., Gordon, J., Iriarte, A., and Martinez-Carrion, M. (1987) Biochem. Biophys. Res. Commun. 149, 859-865). The isolated precursor contains bound pyridoxal phosphate and shows catalytic activity with a specific activity equal to that of the mature form of the enzyme. This precursor can also be processed by mitochondria into a form with the sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobility of mature enzyme. The isolation of this precursor as a stable and catalytically active entity indicates that the presequence peptide does not necessarily interfere with much of the folding and basic structural properties of the mature protein component.
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PMID:Isolation and properties of a liver mitochondrial precursor protein to aspartate aminotransferase expressed in Escherichia coli. 264 43

After racing 722 m, 16 Greyhounds were evaluated to determine changes in hematologic, biochemical, blood-gas, and acid-base values following exercise. Values were determined before racing (T0), immediately after racing (T1), and 3 hours after racing (T2). Significant changes detected immediately after racing included increased heart rate, respiratory rate, and rectal temperature. Significant changes in hematologic values included increases in PCV, total plasma protein, hemoglobin, RBC, WBC, neutrophils, and lymphocytes. Change was not detected in values for monocytes, eosinophils, and neutrophil/lymphocyte ratio. Other increases included those for plasma concentrations of sodium, chloride, calcium, lactic acid, aspartate transaminase, alanine transaminase, alkaline phosphatase, creatine kinase, lactate dehydrogenase, and glucose. Concentrations of potassium and urea did not change. Measurement of blood-gas and acid-base status revealed significant increases in PaO2 and base deficit, whereas PaCO2, pH, and bicarbonate decreased. Three hours after exercise, all vital signs and blood-gas and acid-base values, except for PaCO2, which was still slightly low, had returned to baseline (T0) values. Most biochemical values had also returned to baseline, although sodium, chloride, aspartate transaminase, and creatine kinase were still high, and urea was low. Many hematologic values were still different from baseline values, with high values for WBC, neutrophils and neutrophil/lymphocyte ratio, and low values for PCV, total plasma protein, hemoglobin, RBC, and lymphocytes.
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PMID:Hematologic, biochemical, blood-gas, and acid-base values in greyhounds before and after exercise. 271 27


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