Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In islets from adult rats injected with streptozotocin during the neonatal period, both a nonmetabolized analog of L-leucine and 3-phenylpyruvate augmented 14CO2 output from islets either prelabeled with L-[U-14C]glutamine or exposed to D-[2-14C]glucose and D-[6-14C]glucose, in a manner qualitatively comparable to that found in islets from control rats. The islets of diabetic rats differed, however, from those of control rats by their unresponsiveness to both the L-leucine analog and a high concentration of D-glucose in terms of increasing 3HOH generation from [2-3H]glycerol, an impaired sparing action of the hexose upon 14CO2 output from islets prelabeled with [U-14C]palmitate, and, most importantly, by a decreased rate of D-[2-14C]glucose and D-[6-14C]glucose oxidation when either incubated at a high concentration of the hexose (16.7 mM) or stimulated by nonglucidic nutrient secretagogues at a low concentration of D-glucose (2.8 mM). In islet homogenates, the activity of glyceraldehyde phosphate dehydrogenase, glutamate decarboxylase, and NADP-malate dehydrogenase was lower in diabetic than control islets. Such was not the case for glutamate-alanine transaminase, glutamate-aspartate transaminase, or glutamate dehydrogenase. The neonatal injection of streptozotocin thus affected, in the adult rats, the activity of several islet enzymes. Nevertheless, the metabolic data suggest that an impaired circulation in the glycerol phosphate shuttle, as observed in response to stimulation of the islets by either a high concentration of D-glucose or nonglucidic nutrient secretagogues, represents an essential determinant of the preferential impairment of glucose-induced insulin release in this model of non-insulin-dependent diabetes.
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PMID:Metabolic response to nonglucidic nutrient secretagogues and enzymatic activities in pancreatic islets of adult rats after neonatal streptozotocin administration. 848 60

The pyridoxal-5'-phosphate-dependent enzymes (B(6) enzymes), that operate in the metabolism of amino acids, are of multiple evolutionary origin. To estimate their rates of evolution, a total of 180 sequences of 21 B(6) enzymes from distantly related eukaryotic species were compared. The enzymes belong to all four evolutionarily independent families of B(6) enzymes with different folds, i.e., the large alpha family, the beta family, the d-alanine aminotransferase family, and the alanine racemase family. Their unit evolutionary periods, i.e., the time for a 1% sequence difference to accumulate between branches, ranged from 4.6 to 45.1 million years. Both, fastest changing serine pyruvate aminotransferase and most slowly changing glutamate decarboxylase are members of the alpha family. The evolutionary rates of the few enzymes belonging to the other three families were interspersed among those of the alpha family members. Enzymes that catalyze the same reaction, e.g., transamination or amino acid decarboxylation, with different substrates show widely varying rates. The absence of correlations of the rate of evolution with either protein fold or type of catalyzed reaction suggests that individual functional constraints have determined the differential rates of evolution of B(6) enzymes.
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PMID:Rates of evolution of pyridoxal-5'-phosphate-dependent enzymes. 1075 66

There exist differences between 12-day-old and adult rats in the onset of seizures induced by some inhibitors of glutamate decarboxylase (GAD). The aim of study was to investigate if there are differences between both groups in activities of rat brain alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the enzymes involved in glutamate metabolism, after the administration of 3-mercaptopropionic acid as specific GAD inhibitor or isoniazid as less specific general inhibitor of pyridoxal enzymes. Activities of both aminotransferases in a supernatant 20,000 g of the whole brain (containing predominantly cytosolic isoforms of enzymes) were increased at the beginning of 3-mercaptopropionic acid-induced generalized tonic-clonic seizures. At isoniazid-induced generalized tonic-clonic seizures, a significant increase in both enzyme activities was observed in adult rat brain. In the 12-day-old rat brain, ALT and AST activities reached about 40% and about 50-60% of adult control levels, respectively. In in vitro experiments, no influence of 3-mercaptopropionic acid on transaminase activities was found and an inhibitory effect of isoniazid on the enzymes was confirmed. Increased aminotransferase activities might participate in the enhanced synthesis of excitatory amino acid neurotransmitters in the nervous system, which may take a part in the initiation of epileptic seizures. Alternatively, the increased AST activity may be connected with an increased transport of NADH from the cytosol to mitochondria, while the increased ALT activity would represent the transformation of pyruvate to alanine as a consequence of increased glycolysis.
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PMID:Influence of convulsants on rat brain activities of alanine aminotransferase and aspartate aminotransferase. 1188 79

Unspecific and side effects caused by interaction with proteins belong to common problems of many structures synthesized as potential medicaments. Possible in vitro interactions with proteins of a group of phenylsulfonyl benzoic acid derivatives (VUFB 19363, 19369, 19370, 19371, and 19760) as new potential anti-inflammatory compounds with anti-leukotrienic activities were studied in the present work. Three purified enzymes were used as model proteins with catalytic activities: Pig heart aspartate aminotransferase (AST, EC 2.6.1.1), alanine aminotransferase (ALT, EC 2.6.1.2), and glutamate decarboxylase (GAD, EC 4.1.1.15) from E. coli. Catalytic activities during incubation of individual compounds (6 x 10(-5) M solution to 5 x 10(-2) M suspension) at 37 degrees C with enzymes served as criteria of stability and function of the proteins. No immediate influence of any compound studied on enzyme activities was found. Aminotransferase activities were not affected even during incubation up to 20 d. In the case of GAD, the compounds VUFB 19369, 19370, 19371, and 19760 had stabilizing influence on GAD activity during incubation at enzyme concentrations of 11.25 and 5.62 mg prot/l. The lack of an immediate effect of compounds and the stability of enzymes during incubation them are favorable and support the prospective of the compounds as potential drugs.
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PMID:New potential nonsteroidal anti-inflammatory drugs with antileukotrienic effects: influence on model proteins with catalytic activity. 1214 13

The interactions of two pyridoxal-5-phosphate (PLP)-dependent enzymes, alanine aminotransferase (ALT) and glutamate decarboxylase (GAD), with pyridoxal kinase (PK) were studied by fluorescence polarization as well as surface plasmon resonance techniques. The results demonstrated that PK can specifically bind to ALT and GAD. Moreover, binding profiles of both enzymes to immobilized PK were altered by excess amount of PLP. The equilibrium affinity constants for ALT in the absence and presence of PLP are 20.4 x 10(4) M(-1)and 6.7 x 10(4) M(-1), and for GAD are 37 x 10(4) M(-1)and 20.8 x 10(4) M(-1), respectively. It appears that specific interactions occur between PK and PLP-dependent enzymes, and the binding affinities of PK for PLP-dependent enzymes decrease in the presence of PLP. The results support our hypothesis that PLP transfer from PK to PLP-dependent enzymes requires a specific interaction between PK and the enzyme.
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PMID:Interaction between pyridoxal kinase and pyridoxal-5-phosphate-dependent enzymes. 1468 39

Labeled glutamate was rapidly converted to gamma-aminobutyrate in intact, excised radish (Raphanus sativus L., var. Champion) leaves. Labeled gamma-aminobutyrate was metabolized via succinate and the Krebs cycle and was not carboxylated to form glutamate. Administration of carbon-14 and tritium-labeled succinate indicated that less than 10% of the gamma-aminobutyrate formation occurs by amination of succinic semialdehyde. Therefore, most gamma-aminobutyrate formation must be via glutamate decarboxylation.Radish leaf extracts were more active in catalyzing transamination between gamma-aminobutyrate and pyruvate than that between gamma-aminobutyrate and alpha-ketoglutarate. Glutamate decarboxylase was approximately 20 times more active than gamma-aminobutyrate: pyruvate transaminase. Succinic semialdehyde dehydrogenase was found in the extracts, and NAD was much more active as a hydrogen acceptor than NADP. No reduction of succinate to succinic semialdehyde by the NAD-linked dehydrogenase could be demonstrated. The following pH optima were determined: glutamate decarboxylase, 5.9; gamma-aminobutyrate: pyruvate transaminase, 8.9; succinic semialdehyde: NAD dehydrogenase, about 9.0.
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PMID:In Vivo and In Vitro Studies on gamma-Aminobutyric Acid Metabolism with the Radish Plant (Raphanus sativus, L.). 1665 5

Soybean (Glycine max [L.] Merr) leaves contain a low level (0.05 micromole per gram fresh weight) of gamma-aminobutyric acid (Gaba) but the concentration of this non-protein amino acid increased to 1 to 2 micromoles per gram fresh weight within 5 minutes after transfer of plants or detached leaves from 33 degrees C to 22 degrees C or lower temperatures. A parallel decrease occurred in the concentration of glutamate. Accumulation of Gaba was also triggered by mechanical damage to the soybean leaves, but in plants subjected to a gradual reduction in temperature (2 degrees C per minute) only a small increase in Gaba occurred. A rapid increase in the concentration of alanine and decrease in glycine occurred upon transfer of the soybean plants to darkness and was not influenced by temperature. When plants were returned to normal growing conditions, all changes in amino acid concentrations were fully reversed in 1 hour.In soybean leaf discs incubated with [(14)C]glutamate, a rapid accumulation of [(14)C]Gaba was detected, and glutamate decarboxylase activity of the soybean leaf considerably exceeded (>30-fold) that of Gaba pyruvate transaminase. Part of the transaminase was localized in the mitochondria, but glutamate decarboxylase was not associated with any organelle or membrane component of the leaf cell. We consider that Gaba accumulation results from some change in intracellular compartmentation of the cell triggered by low temperature shock or mechanical damage. The accumulation of alanine due to a light-dark transition could be accounted for by transamination. [(14)C]Alanine formation was demonstrated when soybean leaf extracts were incubated with glutamate, aspartate, or serine and [(14)C]pyruvate.The changes in amino acid concentrations described for soybean leaves were demonstrated for all the vegetative tissues of the soybean plant and at variable rates in the leaves of a range of plant species. The response in detached tomato (Lycopersicon esculentum Mill.) leaves was of a similar magnitude to soybean. Thus, precautions are necessary to minimize changes in amino acid composition induced by manipulation and extraction of plant material.
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PMID:Rapid Accumulation of gamma-Aminobutyric Acid and Alanine in Soybean Leaves in Response to an Abrupt Transfer to Lower Temperature, Darkness, or Mechanical Manipulation. 1666 65

100 mg of taurine per kg body weight had been administered intraperitoneally and 30 min after the administration the animals were sacrificed. Glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, glutaminase, glutamine synthetase, glutamate decarboxylase and GABA aminotransferase along with the content of glutamate and GABA in cerebral cortex, cerebellum and brain stem were studied and compared with the same obtained in the rats treated with normal saline in place of taurine. The results indicated a significant decrease in the activity of glutamate dehydrogenase in cerebral cortex and cerebellum and a significant increase in brain stem. Glutaminase and glutamine synthetase were found to increase significantly both in cerebral cortex and cerebellum. The activities of glutamate decarboxylase was found to increase in all the three regions along with a significant decrease in GABA aminotransferase while the content of glutamate showed a decrease in all the three brain regions, the content of GABA was observed to increase significantly. The above effects of taurine on the metabolism of glutamate and GABA are discussed in relation to the functional role of GABA and glutamate. The results indicate that taurine administration would result in a state of inhibition in brain.
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PMID:Acute metabolic effects of taurine on the enzymes metabolizing glutamate and gaba. 2049 55

This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen.
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PMID:[Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress]. 2534 52


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