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)

Four aminotransferases were identified and characterized from Methanococcus aeolicus. Branched-chain aminotransferase (BcAT, EC 2.6.1.42), aspartate aminotransferase (AspAT, EC 2.6.1.1), and two aromatic aminotransferases (EC 2.6.1.57) were partially purified 175-, 84-, 600-, and 30-fold, respectively. The apparent molecular weight, substrate specificity, and kinetic properties of the BcAT were similar to those of other microbial BcATs. The AspAT had an apparent molecular weight of 162,000, which was unusually high. It had also a broad substrate specificity, which included activity towards alanine, a property which resembled the enzyme from Sulfolobus solfataricus. An additional alanine aminotransferase was not found in M. aeolicus, and this activity of AspAT could be physiologically significant. The apparent molecular weights of the aromatic aminotransferases (ArAT-I and ArAT-II) were 150,000 and 90,000, respectively. The methanococcal ArATs also had different pIs and kinetic constants. ArAT-I may be the major ArAT in methanococci. High concentrations of 2-ketoglutarate strongly inhibited valine, isoleucine, and alanine transaminations but were less inhibitory for leucine and aspartate transaminations. Aromatic amino acid transaminations were not inhibited by 2-ketoglutarate. 2-Ketoglutarate may play an important role in the regulation of amino acid biosynthesis in methanococci.
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PMID:Characterization of amino acid aminotransferases of Methanococcus aeolicus. 172 42

The effects of aminooxyacetic acid (AOAA), a transaminase inhibitor, and 2-oxoglutarate, a precursor to glutamate by the activity of aspartate aminotransferase (AAT), on slices of rat medulla oblongata, cerebellum, cerebral cortex, and hippocampus were studied. The slices were superfused and electrically stimulated. There was a Ca2+-dependent stimulus-evoked release of endogenous glutamate, gamma-aminobutyric acid (GABA), and beta-alanine in all regions examined. AOAA (10(-4) and 10(-3) M) decreased the release of glutamate in the medulla oblongata and cerebellum but not in the hippocampus. L-Canaline, a specific inhibitor of ornithine aminotransferase, did not affect the glutamate release in the medulla. 2-Oxoglutarate (10(-3) M) increased the release of glutamate in the medulla oblongata and cerebellum but not in the cerebral cortex and hippocampus. Treatment with AOAA (10(-4) M) almost abolished the activities of AAT in all regions studied. AOAA (10(-4) and 10(-3) M) increased the stimulus-evoked release of GABA in the cerebellum, cerebral cortex, and hippocampus, whereas the stimulus-evoked release of beta-alanine was decreased by this agent in all regions studied. These results suggest the participation of AAT in the synthesis of the transmitter glutamate in the medulla oblongata and cerebellum of the rat.
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PMID:Aspartate aminotransferase for synthesis of transmitter glutamate in the medulla oblongata: effect of aminooxyacetic acid and 2-oxoglutarate. 256 22

Transaminative metabolism of L-cysteine was investigated using homogenates of guinea pig liver and kidney. L-Cysteine was transaminated in the presence of 2-oxoglutarate and the homogenate of either liver or kidney. S-(2-Hydroxy-2-carboxyethylthio)cysteine (HCETC) (3-mercaptolactate-cysteine disulfide) was formed by liver homogenate, but the amount was very small. On the other hand, a relatively large amount of HCETC was formed in the presence of kidney homogenate. Transamination between 3-mercaptopyruvate and certain amino acids was catalyzed actively by both liver and kidney homogenates in the presence of L-glutamate. However, more half-cysteine was formed by liver than kidney, and more HCETC was produced by kidney than liver. L-Glutamate was the most potent amino donor, and L-aspartate strongly inhibited the reaction. Results indicate that L-cysteine can be transaminated both in liver and kidney of the guinea pig, and that kidney is more active than liver. 2-Oxoglutarate is the most active 2-oxo acid for cysteine transamination. Oxaloacetate (and aspartate in the reverse reaction) is inhibitory to the reaction. These results are in agreement with the previous conclusion that cysteine aminotransferase is identical with aspartate aminotransferase.
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PMID:Transaminative metabolism of L-cysteine in guinea pig liver and kidney. 649 71