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PubMedDate not supplied

[Changes in the blood serum aminotransferase activity in the experimental infection of Cercopithecus aethiops monkeys with the Marburg virus].

Aminotransferase levels in the peripheral blood serum of African green monkeys were studied after aerosol infection with lyophilized virus preparation. A correlation between aminotransferase activity and other symptoms of hemorrhagic fever was shown. Considerable variations in the features of aminotransferase activity in severe and mild cases of the disease were observed.

Alanine Transaminase↗

PubMed2005

[Effect of estragole on glucocorticoid induction of tyrosine aminotransferase and tryprophan oxygenase in the rat and mouse liver].

A single intraperitoneal injection of Estragole (300 mg/kg) to female ICR mice 19 hours prior to Dexamethasone induction decreased induced activities of tyrosine aminotransferase (TAT) and tryptophan oxygenase (TO) nearly to 50% of the control values. In these mice, activities of the marker enzymes of liver damage: alanine aminotransferase (ALAT) and aspartate aminotransferase (AAT) increased in the blood 1.7-2.3-fold as compared with the untreated controls. By contrast, carbon tetrachloride (100 mg/kg) increased the blood AIAT and AsAT activities 135- and 30-fold as compared with the control, but inhibited the TAT and TO induction much less than Estragole did. Estragole seems to inhibit the glucocorticoid induction of these hepatic enzymes not via the unspecific toxic damage of the liver.

Alanine Transaminase↗

PubMedDate not supplied

[Molecular evolution of glycogen phosphorylase and aminotransferases of vertebrate muscle tissue].

Comparative biochemical studies on phosphorylase b, aspartate aminotransferase and alanine aminotransferase in muscles of various vertebrates (the lamprey Lampetra fluviatilis, dogfish Squalus acanthias, rays Dasyatis pastinaca and Raja clavata, teleosts Scorpaena porcus, Spicara smaris, Esox lucius, Tinca tinca, Abramis brama, Lucioperca lucioperca, Cyprinus carpio, Salmo ischchan, frog Rana temporaria, tortoise Testudo horsfieldi) revealed some peculiarties of their molecular evolution. It was shown that isoenzyme PH-II, which comprises in most on the investigated lower vertebrates the main bulk of phosphorylase b, disappears in evolution of the type. Isoenzyme PH-I which is found in fisches in small amounts, increases in evolution becoming the sole form of phosphorylase b in skeletal muscles of endothermic animals. Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase were found in all the vertebrates studied. Cytoplasmic isoenzyme from ectothermic and endothermic animals does not differ significantly, whereas the mitochondrial one undergoes considerable changes in the evolution of vertebrates.

Alanine Transaminase↗

PubMed1991

Thermostable aspartate aminotransferase from a thermophilic Bacillus species. Gene cloning, sequence determination, and preliminary x-ray characterization.

The gene encoding aspartate aminotransferase of a thermophilic Bacillus species, YM-2, has been cloned and expressed efficiently in Escherichia coli. The primary structure of the enzyme was deduced from nucleotide sequences of the gene and confirmed mostly by amino acid sequences of tryptic peptides. The gene consists of 1,176 base pairs encoding a protein of 392 amino acid residues; the molecular mass of the enzyme subunit is estimated to be 42,661 daltons. The active site lysyl residue that binds the coenzyme, pyridoxal phosphate, was identified as Lys-239. Comparison of the amino acid sequence with those of aspartate aminotransferases from other organisms revealed very low overall similarities (13-14%) except for the sequence of the extremely thermostable enzyme from Sulfolobus solfataricus (34%). Several amino acid residues conserved in all the compared sequences include those that have been reported to participate in binding of the coenzyme in three-dimensional structures of the vertebrate and E. coli enzymes. However, the strictly conserved arginyl residue that is essential for binding of the distal carboxyl group of substrates is not found in the corresponding region of the sequences of the thermostable enzymes from the Bacillus species and S. solfataricus. The Bacillus aspartate aminotransferase has been purified from the E. coli clone cell extracts on a large scale and crystallized in the buffered ammonium sulfate solution by the hanging drop method. The crystals are monoclinic with unit cell dimensions a = 121.2 A, b = 110.5 A, c = 81.8 A, and beta = 97.6 degrees, belonging to space group C2, and contain two molecules in the asymmetric unit. The crystals of the enzyme-alpha-methylaspartate complex are isomorphous with those without the substrate analog.

Amino Acid Sequence↗

PubMed1991

Inhibition of cytoplasmic aspartate aminotransferase from porcine heart by R and S isomers of aminooxysuccinate and hydrazinosuccinate.

D- and L-aminooxysuccinate were synthesized and evaluated as inhibitors of cytoplasmic aspartate aminotransferase (EC 2.6.1.1) from porcine heart. L-Aminooxysuccinate was shown to be a slow binding inhibitor of the pyridoxal phosphate form of the enzyme with a Ki of 160 nM and a half-life of the inhibited complex of 8 min. Kinetic analysis revealed that inhibition followed a two-step mechanism in which the last step was rate-limiting. D-Aminooxysuccinate was not inhibitory up to a concentration of 0.1 mM. These compounds were compared to D- and L-hydrazinosuccinate, which are potent slow binding inhibitors of aspartate aminotransferase with Ki values of 1.5 and 0.5 nM, respectively. Models of all four analogs were built into the active site of the closed form of the enzyme. The energy-minimized conformations of both L-isomers bound to aspartate aminotransferase show better geometry for hydrogen bond and ion pair formation than do the corresponding D-isomers. The aldimine double bond formed by the L-isomers is not coplanar with the pyridoxal phosphate ring in accordance with the spectral properties of the inhibitor complexes that are characterized by broad absorbance bands. This lack of planarity was not evident for the models of D-hydrazinosuccinate and D-aminooxysuccinate.

Animals↗

PubMed1990

Molecular cloning and sequence analysis of the human cytosolic aspartate aminotransferase gene.

Structural organization of the human cytosolic aspartate aminotransferase gene was determined by analyzing the phage clones obtained from two kinds of genomic DNA libraries, using mouse cytosolic aspartate aminotransferase cDNA as a probe. The gene is more than 32 kb long and is split into 9 exons by 8 introns of various sizes. The 5' and 3'-flanking regions and the exact sizes and boundaries of the exon blocks were determined. The 5' end of the gene lacks the TATA and CAAT boxes, but contains G+C rich sequences and one potential binding site for the transcription factor, Sp1. Comparison of the nucleotide sequence of 250 bp upstream from the translation-initiation site revealed that the sequences of binding sites for the nuclear proteins, previously identified in the mouse, are highly conserved between human and mouse cytosolic aspartate aminotransferase genes.

Amino Acid Sequence↗

PubMedDate not supplied

[Aminotransferase and dehydrogenase activity in human brain tumours].

Asparate and alanine aminotransferase activity is approximately the same in different lobes of cerebral hemispheres of people with an uninjured central nervous system. The maximal activity of lactate, malate and succinate dehydrogenase is in the temporal lobes and thalami, the minimal one is in the corpus callosum. The activity of aminotransferases in the brain tumour lowers: in the dedifferentiated tumour the asparate aminotransferase shows a 23-24% decrease; in the case of the meningeal sarcoma it is 2.5 times as low: the activity of alaine aminogransferase is almost 10 times as low. The activity of malate dehydrogenase decreases in the neuroectodermal tumours and sharply (almost twice) in multiform glioblastoma. In the dedifferentiated meningiomas the activity of all the dehydrogenases is increased.

Adult↗

PubMed1990

Drug-induced decrease of serum alanine and aspartate aminotransferase activity in the rat, as a result of treatment with oxodipine, a new calcium channel blocker.

Chronic oral administration of oxodipine, a new calcium channel blocker, resulted in a reduction in the blood enzyme activity of alanine and aspartate aminotransferase. The reductions were both time and dose related. The decline in enzyme activities was accompanied by microscopic hepatic changes, which in the opinion of the authors should have been associated with an increase in the enzyme activities of alanine aminotransferase and aspartate aminotransferase. The effect was only partially reversed one month after the cessation of oxodipine treatment.

Alanine Transaminase↗

PubMed1975

Stimulation of tyrosine aminotransferase activity by dl-alpha-methyltryptophan.

DL-alpha-Methyltryptophan (alphaMeTrp), a synthetic analogue of tryptophan, has been found to be a potent inducer of hepatic tyrosine aminotransferase activity in the adrenalectomized rat. alphaMeTrp is inactive in vitro. Unlike the action of other known inducers (tryptophan, hydrocortisone, adenosine cyclic 3:5-monophosphate, and glucagon), maximal stimulation of enzyme activity occurs only 16 to 30 hours after alphaMeTrp administration and the activity is still elevated at 96 hours. Only the L isomer of alphaMeTrp is active, and addition of a hydroxyl group to position 5 of the indole ring renders an inactive compound. The induction can be prevented by actinomycin D or cycloheximide but not galactosamine. Administration of alphaMeTrp together with hydrocortisone produced an additive stimulation of enzyme activity. alphaMeTrp given along with glucagon or adenosine cyclic 3:5-monophosphate caused a further but not additive increase in enzyme activity. Tryptophan given along with alphaMeTrp promoted no extra stimulation whatsoever. These data indicate that alphaMeTrp and tryptophan may act via a common pathway which in part requires RNA synthesis. Other enzymes, namely alanine and aspartate aminotransferase, ornithine aminotransferase, ornithine carbamoyltransferase, serine dehydratase, and histidine ammonialyase, were not affected by treatment of rats with alphaMeTrp.

Adrenalectomy↗

PubMed1975

Factors contributing to the inhibition of aspartate aminotransferase by dicarboxylic acids.

At pH 8.0 aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) reacts with the modified substrate, erythro-beta-hydroxy-L-aspartate, to form a mixture of enzyme-substrate complexes absorbing at 492 nm. A variety of dicarboxylic acids were studied spectrophotometrically as competitive inhibitors of this reaction. All of the inhibitory dicarboxylic acids form a complex with the enzyme, absorbing at 362 nm. In addition, some of the dicarboxylic acids form a protonated complex absorbing at about 435 nm. This complex, which is the conjugate acid of that absorbing at 362 nm, is formed only by those dicarboxylic acids which can assume a configuration in which the two carboxyl groups are positioned as in maleic acid. Bulky substituents, such as aromatic rings or even methyl groups, prevent the formation of the protonated complex, presumably because of steric restrictions at the active site. Substitution of the central carbon atom of glutaric acid by heteroatoms of increasing charge density results in a progressive decrease in inhibitory effectiveness, at pH 8, primarily due to a loss of this pH-dependent stabilization of the enzyme-dicarboxylic acid complex. Acids with an aromatic ring are among the most potent dicarboxylic acid inhibitors of this enzyme in spite of the fact that they do not undergo the pH-dependent stabilization of their enzyme complexes. From these observations it was concluded that the affinity of aspartate aminotransferase for dicarboxylic acids is determined as much by the mechanism of binding as by the solvation and steric effects.

Animals↗

PubMed1989

Mitochondrial aspartate aminotransferase by immunoprecipitation method in patients with acute myocardial infarction.

The semiautomated kinetic procedure for determining cytoplasmic aspartate aminotransferase (c-AST) and mitochondrial aspartate aminotransferase (m-AST) activities was studied by the use of the immunoprecipitation method with anti-c-AST antibody in serum samples. The measured activity for m-AST remained constant after the addition of c-AST up to 1,000 IU/l throughout the 60-min incubation period. The measurements of m-AST activity were reproducible, selective and complete as determined by a purified m-AST. The precision of this method was as good as that of the manual method (CV 2.04%). The present method and the manual method gave approximately equal results for m-AST (r = 0.987). The effects of activations on m- and c-AST activity were compared by the addition of pyridoxal 5'-phosphate to sera of various diseases. A higher activation ratio by pyridoxal 5'-phosphate was observed on both aspartate aminotransferase activities in the serum of patients with ischemic heart diseases than in the serum of patients with liver diseases.

Adult↗

PubMed1989

[Serum activity of mitochondrial aspartate aminotransferase and extrahepatic cholestasis].

Serum mitochondrial aspartate aminotransferase (mAST) level and the mitochondrial aspartate aminotransferase/total aspartate aminotransferase ratio (mAST/AST) have been proposed as sensitive markers of chronic alcoholism. Their specificity, however, remains poorly defined. The purpose of this study was to compare these markers in three groups of hospitalized patients: group I, 80 patients with chronic alcoholic liver disease; group II, 51 patients with chronic liver disease without alcoholism; group III, 44 patients with extrahepatic cholestasis (due to choledocholithiasis in 21 and malignant in 23). mAST was measured after immuno-precipitation of cytoplasmic aspartate aminotransferase. The normal values of mAST (less than or equal to 2 mu/l) and mAST/AST (less than or equal to 6 p. 100) were defined in a group of 59 non alcoholic subjects without liver disease (controls). mAST was increased as compared with controls in 91 p. 100 of the patients of group I, 20 p. 100 of group II, 61 p. 100 of group III. mAST was comparable in groups I (mean +/- SD: 10 +/- 10.8) and III (10.3 +/- 12.9), and higher than in group II (1.8 +/- 2.4). m/AST was increased in 59 p. 100 of the patients of group I, 6 p. 100 of group II and 36 p. 100 of group III. It was higher in group I (8 +/- 4 p. 100) than in group III (6 +/- 4 p. 100, p less than 0.02), and particularly higher in both these groups than in group II (2 +/- 1 p. 100, p less than 0.00001). mAST was correlated to AST in each of these three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗

PubMed1988

Purification and characterization of aspartate aminotransferase from the thermoacidophilic archaebacterium Sulfolobus solfataricus.

Aspartate aminotransferase from the archaebacterium Sulfolobus solfataricus, a thermoacidophilic organism isolated from an acidic hot spring (optimal growth conditions: 87 degrees C, pH 3.5) was purified to homogeneity. The enzyme is a dimer (Mr subunit = 53,000) showing microheterogeneity when submitted to chromatofocusing and/or isoelectric focusing analysis (two main bands having pI = 6.8 and 6.3 were observed). The N-terminal sequence (22 residues) does not show any homology with any stretch of known sequence of aspartate aminotransferases from animal and bacterial sources. The apoenzyme can be reconstituted with pyridoxamine 5'-phosphate and/or pyridoxal 5'-phosphate, each subunit binding 1 mol of coenzyme. The absorption maxima of the pyridoxamine and pyridoxal form are centered at 325 and 335 nm, respectively; the shape of the pyridoxal form band does not change with pH. The enzyme has an optimum temperature higher than 95 degrees C, and at 100 degrees C shows a half-inactivation time of 2 h. The above properties seem to be unique even for enzymes from extreme thermophiles (Daniel, R. M. (1986) in Protein Structure, Folding, and Design (Oxender, D. L., ed) pp. 291-296, Alan R. Liss, Inc., New York) and lead to the conclusion that aspartate aminotransferase from S. solfataricus is one of the most thermophilic and thermostable enzymes so far known.

Amino Acid Sequence↗

PubMed1987

Expression of cDNAs encoding the precursor and the mature form of chicken mitochondrial aspartate aminotransferase in Escherichia coli.

Both the precursor and the mature form of chicken mitochondrial aspartate aminotransferase were synthesized in Escherichia coli. The precursor was found to sediment quantitatively together with insoluble cell material. In contrast, mature mitochondrial aspartate aminotransferase could be readily extracted from the cells and was indistinguishable from the enzyme isolated from chicken heart in all respects tested: specific activity 230 units mg-1; Mr 2 X 45,000; pI greater than 9; NH2-terminal sequence SSWWSHVEMG, the initiator methionine having been removed by the bacteria. Thus, the polypeptide chain representing mature mitochondrial aspartate aminotransferase is an autonomous folding unit which attains its functional spatial structure independently of the presence of the prepiece, trans-membrane passage, and proteolytic processing.

Amino Acid Sequence↗

PubMed1988

[Diagnostic value of aspartate aminotransferase in the cerebrospinal fluid].

As datum, the range of aspartate aminotransferase in the cerebrospinal fluid of adults was determined on the basis of 153 fluid samples and compared with the values obtained from 356 neurological patients. A significant increase in enzyme activity was established in respect of CVI, polyneuropathy, acute encephalitis, and SAB. It was possible to eliminate any dependence of the aspartate aminotransferase activity on serum activity, total protein, and cell count. The increase in activity of aspartate aminotransferase in the cerebrospinal fluid is thus identified as an independent pathological fact, and thus it can be incorporated in diagnostic routine more particularly in the diagnosis of CVI disorders.

Aspartate Aminotransferases↗

PubMed1988

Induction of cytosolic aspartate aminotransferase by a high-protein diet.

Induction of cytosolic aspartate aminotransferase (glutamic oxaloacetic transaminase) was observed in rat liver on administration of a high-protein diet. The enzyme activity in the liver of rats given 60% and 80% protein diet increased to 1.8- and 1.9-fold that in the liver of rats maintained on 20% protein diet, with about 2-fold increases in the levels of functional sGOT mRNA, measured by in vitro translation. Whereas the activity of mitochondrial aspartate aminotransferase did not increase. Induction of cytosolic aspartate aminotransferase was also detected immunocytochemically.

Animals↗

PubMed1986

Plasma clearance of mitochondrial aspartate aminotransferase in the rat: competition with mitochondrial malate dehydrogenase.

In previous experiments we have shown that the rapid clearance in rats of alcohol dehydrogenase, lactate dehydrogenase M4, and the mitochondrial and cytosolic isoenzymes of malate dehydrogenase is largely due to endocytosis by macrophages in liver, spleen and bone marrow. Competition experiments indicated that the dehydrogenases as well as adenylate kinase and creatine kinase MM are endocytosed via the same receptor. We suggested that this receptor contains a group with affinity for the nucleotide-binding sites of the enzymes. We now demonstrate that competition also occurs between mitochondrial malate dehydrogenase and mitochondrial aspartate aminotransferase, which does not require a nucleotide for its activity. At low doses, mitochondrial aspartate aminotransferase was cleared following first-order kinetics (half-life: 19 min). Simultaneous injection of a high dose of mitochondrial malate dehydrogenase strongly retarded the clearance of the aminotransferase. These results make unlikely the hypothesis that a nucleotide-binding site is involved in recognition of enzymes by macrophages.

Animals↗

PubMedDate not supplied

[Aspartate aminotransferase activity of different strains of Escherichia coli].

Aspartate-aminotransferase activity was measured in strains of Escherichia coli grown no meat infusion broth. As an enzyme cells with damaged permeability of the cytoplasmatic membrane were used. The cells were damaged by an addition of toluene at a concentration of 1% of the reaction mixture by volume. These cells showed 50--60% aspartate-aminotransferase activity as compared with aliquotes of the cell-free extract. E. coli synthesized oxalacetic and glutamic acids from L-aspartic acid and alpha-ketoglutaric acid. Glutamic acid was identified by thin-layer chromatography on Fixion plates. E. coli str. 85 cells and their extracts grown on the synthetic medium containing glucose or glycerol showed a two-fold specific aspartate-aminotransferase activity as compared with those cultivated on meat-infusion broth.

Aspartate Aminotransferases↗