Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.1.1.41 (isocitrate dehydrogenase)
 3,101 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The occurrence and subcellular distribution of arginase have been studied in mammary glands from lactating dairy cattle. The enzyme appears to be localized in the mitochondrial fraction, although a significant amount has been found to be associated with the cytosolic fraction. Both mitochondrial and cytosolic arginase are activated by heating with Mn2+. The Michaelis constants for the two fractions, however, are different: 49.5 and 18.5 mM for the mitochondrial fraction and cytosolic fraction, respectively. Overall the total enzyme concentration in the gland suggests that these enzymes contribute to the conversion of arginine to ornithine. Ornithine, in turn, may be converted by ornithine aminotransferase into an intermediate, L-delta 1-pyrroline-5-carboxylate; concurrently. alpha-keto-glutarate is transformed into glutamic acid. Finally, pyrroline-5-carboxylate reductase yields proline, an important amino acid that is needed for casein synthesis. Because pyrroline-5-carboxylate reductase requires NADPH, and because ornithine aminotransferase uses alpha-ketoglutarate, this new pathway is linked to the Krebs cycle through the cytosolic isocitrate dehydrogenase, which is the source of both of these intermediates.
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PMID:Arginase in lactating bovine mammary glands: implications in proline synthesis. 943 5

Systematic protein expression studies in the brain of exercising and sedentary animals have not been carried out so far and it was therefore decided to determine differences in metabolic protein levels in rat hippocampus of sedentary, voluntary and involuntary exercising rats by a proteomic approach. Aged, male Sprague-Dawley rats, 23 months old, were used for the study: the first group consisted of sedentary rats, the second of rats with voluntary exercise from five to 23 months and the third group was performing involuntary exercise on a treadmill from five to 23 months. Two-dimensional gel electrophoresis with subsequent mass spectrometrical identification of spots followed by quantification of spots was carried out. Identification of significantly differential proteins was validated by the determination of the corresponding enzyme activity. Five individual metabolic proteins showed differential protein levels in the three groups: mitochondrial precursors of ornithine aminotransferase, isocitrate dehydrogenase [NAD] subunit alpha, malate dehydrogenase, ubiquinol-cytochrome-c reductase complex core protein 1, and ubiquitin carboxyl-terminal hydrolase isozyme L1. The unambiguously identified metabolic proteins were mainly of mitochondrial localization and fit the expectations of altered mitochondrial activity in exercise. Reduced ubiquitin carboxyl-terminal hydrolase isoenzyme L1 levels in treadmill (forced) exercise show the involvement of the proteasomal pathway as a novel finding. These results not only form the basis for functional studies elucidating mechanisms and differences between voluntary and forced exercise in hippocampal metabolism but also highlight the most intriguing aspect that exercise is affecting the brain at the protein level.
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PMID:Hippocampal metabolic proteins are modulated in voluntary and treadmill exercise rats. 1845 60

We report the molecular characterization and functional analysis of a gene (PsdeltaOAT) from Scots pine (Pinus sylvestris) encoding Orn-delta-aminotransferase (delta-OAT; EC 2.6.1.13), an enzyme of arginine metabolism. The deduced amino acid sequence contains a putative N-terminal signal peptide for mitochondrial targeting. The polypeptide is similar to other delta-OATs from plants, yeast, and mammals and encoded by a single-copy gene in pine. PsdeltaOAT encodes a functional delta-OAT as determined by expression of the recombinant protein in Escherichia coli and analysis of the active enzyme. The expression of PsdeltaOAT was undetectable in the embryo, but highly induced at early stages of germination and seedling development in all different organs. Transcript levels decreased in later developmental stages, although an increase was observed in lignified stems of 90-d-old plants. An increase of delta-OAT activity was observed in germinating embryos and seedlings and appears to mirror the observed alterations in PsdeltaOAT transcript levels. Similar expression patterns were also observed for genes encoding arginase and isocitrate dehydrogenase. Transcripts of PsdeltaOAT and the arginase gene were found widely distributed in different cell types of pine organs. Consistent with these results a metabolic pathway is proposed for the nitrogen flow from the megagametophyte to the developing seedling, which is also supported by the relative abundance of free amino acids in embryos and seedlings. Taken together, our data support that delta-OAT plays an important role in this process providing glutamate for glutamine biosynthesis during early pine growth.
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PMID:Molecular and functional analyses support a role of Ornithine-{delta}-aminotransferase in the provision of glutamate for glutamine biosynthesis during pine germination. 1862 80