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 mechanism of C4 acid decarboxylation was studied in bundle sheath cell strands from Urochloa panicoides, a phosphoenolpyruvate carboxykinase (PCK)-type C4 plant. Added malate was decarboxylated to give pyruvate and this activity was often increased by adding ADP. Added oxaloacetate or aspartate plus 2-oxoglutarate (which produce oxaloacetate via aspartate aminotransferase) gave little metabolic decarboxylation alone but with added ATP there was a rapid production of PEP. For this activity ADP could replace ATP but only when added in combination with malate. In addition, the inclusion of aspartate plus 2-oxoglutarate with malate plus ADP often increased the rate of pyruvate production from malate by more than twofold. Experiments with respiratory chain inhibitors showed that the malate-dependent stimulation of oxaloacetate decarboxylation (PEP production) was probably due to ATP generated during the oxidation of malate in mitochondria. We could provide no evidence that photophosphorylation could serve as an alternative source of ATP for the PEP carboxykinase reaction. We concluded that both PEP carboxykinase and mitochondrial NAD-malic enzyme contribute to C4 acid decarboxylation in these cells, with the required ATP being derived from oxidation-linked phosphorylation in mitochondria.
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PMID:Photosynthesis in phosphoenolpyruvate carboxykinase-type C4 plants: pathways of C4 acid decarboxylation in bundle sheath cells of Urochloa panicoides. 334 40

The culture forms of 30 T. cruzi stocks originating from different parts of Brazil and Venezuela were screened by starch-gel electrophoresis for the isoenzyme patterns of 9 enzymes: glucose-6-phosphate dehydrogenase (G6PD), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), aspartate aminotransferase (ASAT), "malic" enzyme (ME), alanine aminotransferase (ALAT), peptidases (PEP 1, PEP 2) and malate dehydrogenase (MDH). G6PD, PGM, GPI to some extent also ASAT, ME patterns divide 25 stocks into two distinct main groups A and B. The Brazilian stocks of group A originated from different wild animal species only, those of group B were with one exception isolated from human patients, or domestic hosts. In contrast all stocks from Venezuela regardless of their original host belonged to group A. The results of all enzymes showed group A (16 stocks and 7 profiles) to be more homogeneous than group B (9 stocks and 7 profiles). Comparison of these results with previous results of isoelectric focusing of the same stocks shows both methods to be complementary. The two methods gave identical classification of stocks with G6PD, PGM and GPI, both methods dividing most stocks into two main groups. The enzymes ALAT and ASAT confirmed this grouping to some extent in the starch-gel electrophoresis. For both starch-gel and isoelectric focusing ME was of only limited value because of variable enzyme activities in the trypanosome extracts. For the enzymes PEP 1, and PEP 2 and MDH neither method was useful in demonstrating intraspecific variation within the T. cruzi complex.
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PMID:The characterization of Trypanosoma cruzi stocks by starch-gel electrophoresis, comparison of results with those of isoelectric focusing. 622 25

Nodulated lupins (Lupinus angustifolius cv. Wonga) were hydroponically grown under conditions of low phosphate (LP) or adequate phosphate (HP) to assess the effect of phosphoenolpyruvate carboxylase (PEPC)-derived organic acids on nitrogen assimilation in LP nodules. LP conditions are linked to altered organic acid metabolism, by the engagement of PEP metabolism via PEPC. In LP nodules, the enhanced organic acid synthesis may reduce the available organic carbon for nitrogen assimilation. The diversion of carbon between the organic acid- and amino acid pools was assessed through key nodular enzymes and (14)CO(2) metabolism. Under LP conditions, increased rates of organic acid synthesis via PEPC and malate dehydrogenase (MDH), coincided with reduced nitrogen assimilation via aspartate aminotransferase (AAT), aspartate synthetase (AS) and glutamine synthetase (GS)/glutamate synthase (GOGAT) activities. There was a preferential metabolism of nodular (14)CO(2) into organic acids and particularly into malate. High malate levels were associated with reduced N(2) fixation and synthesis of amino acids. These results indicate that phosphorus deficiency can enhance malate synthesis in nodules, but that excessive malate accumulation may inhibit N(2) fixation and nitrogen assimilation.
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PMID:Organic acid accumulation may inhibit N2 fixation in phosphorus-stressed lupin nodules. 1806 56