Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.1.1.41 (isocitrate dehydrogenase)
3,101 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mutant was isolated that failed to derepress the 5' upstream region of Candida tropicalis isocitrate lyase gene (UPR-ICL)-mediated gene expression in acetate medium, and the gene (FIL1) that complemented this mutation was isolated. The fil1 null mutant in which FIL1 is disrupted (deltafil1 strain) could not grow on acetate or ethanol, and the derepression of the isocitrate lyase encoded by ICL1 in Saccharomyces cerevisiae was also defected. The amino acid sequence of Fil1p (230 amino acids) showed similarity to ribosome recycling factors (RRFs) of prokaryotes. Compared to prokaryotic RRFs, Fil1p had an N-terminal 46-amino-acid extension which was shown to be able to function as a mitochondrial-targeting sequence. The subcellular fractionation of the deltafil1 strain showed that protein constituents of the mitochondrial fraction of the deltafil1 strain differed from those of the wild-type strain, but resembled those of chloramphenicol-treated cells or rho(o) cells. The specific activity of cytochrome c oxidase, was severely decreased in deltafil1, rho(o) and chloramphenicol-treated cells compared with wild-type cells, while enzymatic levels of mitochondrial NAD+-linked isocitrate dehydrogenase, which is encoded by nuclear DNA, were not affected. These results suggest that Fillp is necessary for protein synthesis in mitochondria of S. cerevisiae. Furthermore, cells treated with antimycin A, along with chloramphenicol-treated, rho(o), and deltafil1 cells, showed deficiency in derepression of isocitrate lyase. Northern-blot analysis showed that this can be ascribed to no increase in transcription of ICL1 and FBP1 encoding fructose 1,6-bisphosphatase. The results indicate the presence of a communication pathway between mitochondria and the nucleus which represses expression of genes encoding the key enzymes of the glyoxylate cycle and gluconeogenic pathway when there is a deficiency in the mitochondrial respiratory chain.
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PMID:A regulatory factor, Fil1p, involved in derepression of the isocitrate lyase gene in Saccharomyces cerevisiae--a possible mitochondrial protein necessary for protein synthesis in mitochondria. 974 66

The influence of thyroxine on the activities of enzymes of energy metabolism (hexokinase, 6-phosphofructokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase, cytochrome c oxidase) was investigated in bone marrow myeloid cells and blood neutrophils of 3-10-day old neonatal piglets. Data obtained suggest different responsiveness of energy metabolism enzymes to thyroxine action. Repeated hormone injections resulted in the preferential stimulation of enzymes involved in oxidative stages of carbohydrate catabolism in animal myelocaryocytes, while the activities of anaerobic enzymes in these cells were less affected. At the same time glycolytic enzymes in neutrophil granulocytes showed higher sensitivity to thyroxine action than enzymes catalyzing oxidative stages of energy metabolism.
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PMID:[Effect of thyroxine on the activity of some enzymes of energy metabolism in bone marrow myeloid cells and blood neutrophils from piglets]. 1088 37

The capacity of white adipose tissue mitochondria to support a high beta-oxidative flux was investigated by comparison to liver mitochondria. Based on marker enzyme activities and electron microscopy, the relative purity of the isolated mitochondria was similar thus allowing a direct comparison on a protein basis. The results confirm the comparable capacity of adipose tissue and liver mitochondria for palmitoyl-carnitine oxidation. Relative to liver, both citrate synthase and alpha-ketoglutarate dehydrogenase were increased 7.87- and 10.38-fold, respectively. In contrast, adipose tissue NAD-isocitrate dehydrogenase was decreased (2.85-fold). Such modifications in the citric acid cycle are expected to severely restrict citrate oxidation in porcine adipose tissue. Except for cytochrome c oxidase, activities of the enzyme complexes comprising the electron transport chain were not significantly different. The decrease in adipose cytochrome c oxidase activity could partly be attributed to a decreased inner membrane as suggested by lipid and enzyme analysis. In addition, Western blotting indicated that adipose and liver mitochondria possess similar quantities of cytochrome c oxidase protein. Taken together these results indicate that not only is the white adipose tissue protoplasm relatively rich in mitochondria, but that these mitochondria contain comparable enzymatic machinery to support a relatively high beta-oxidative rate.
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PMID:Biochemical properties of porcine white adipose tissue mitochondria and relevance to fatty acid oxidation. 1143 34

Arsenic exists ubiquitously in our environment and various forms of arsenic circulate in air, water, soil and living organisms. Since arsenic compounds have shown to exert their toxicity chiefly by generating reactive oxygen species, we have evaluated the effect of antioxidants ascorbic acid and alpha-tocopherol on lipid peroxidation, antioxidants and mitochondrial enzymes in liver and kidney of arsenic exposed rats. A significant increase in the level of lipid peroxidation and decrease in the levels of antioxidants and in the activities of mitochondrial enzymes were observed in arsenic intoxicated rats. Co-administration of arsenic treated rats with ascorbic acid and alpha-tocopherol showed significant reduction in the level of lipid peroxidation and elevation in the levels of ascorbic acid, alpha-tocopherol, glutathione and total sulfhydryls and in the activities of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, NADH-dehydrogenase and cytochrome c oxidase. From our results, we conclude that ascorbic acid and alpha-tocopherol alleviate arsenic- induced alterations in mitochondria.
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PMID:Ascorbic acid and alpha-tocopherol as potent modulators on arsenic induced toxicity in mitochondria. 1291 23

1. Mitochondria and fluffy layer were prepared from control and regenerating rat liver. Differential and density-gradient centrifugation were used to fractionate the preparations, which were examined for protein content, density and the activity of cytochrome c oxidase, succinate dehydrogenase, NAD-isocitrate dehydrogenase and NADP-isocitrate dehydrogenase. 2. During regeneration the mitochondrial protein content of the liver fell by 18% from the control value of 18.4mg. of protein/g. of liver (wet wt.) and by 3 weeks had risen to 130% of the control value. It then declined slowly. 3. The fluffy-layer protein content (4.7mg./g. of liver) varied inversely as the mitochondrial content and increased by 70% in the early stages (10 days) of liver regeneration. The results suggest that fluffy layer may partially represent both partly formed and broken-down mitochondria. 4. NAD- and NADP-isocitrate dehydrogenases differed in their behaviour during liver regeneration. 5. The succinate-dehydrogenase and NADP-isocitrate-dehydrogenase activity of fluffy layer was high and rose during the early stages of liver regeneration (1 week). Succinate dehydrogenase and cytochrome c oxidase were concentrated in the lighter fluffy-layer particles 10 days to 3 weeks after partial hepatectomy. The significance of this with respect to mitochondrial formation is discussed. 6. Mitochondrial fractions possessed a certain degree of heterogeneity in enzymic activity when separated according to size and density. The mean density of heavy mitochondria was 1.198, light mitochondria 1.193. Fluffy layer was nearly homogeneous in control liver, but during regeneration considerable heterogeneity became evident. The significance of the heterogeneity is discussed.
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PMID:SOME FEATURES OF MITOCHONDRIA AND FLUFFY LAYER IN REGENERATING RAT LIVER. 1433 47

Aging is characterized by a general decline in physiological functions that affects many tissues and increases the risk of death. Deterioration of mitochondria, the major source and target of reactive oxygen species (ROS), is implicated in aging and a variety of age-related diseases. In the present study, the activities of citric acid cycle enzymes, such as isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase, were found to be decreased in aged rats as well as that of electron-transferring enzymes such as NADH dehydrogenase and cytochrome c oxidase. After supplementation of carnitine to aged rats, the activities of these enzymes reverted nearer to that of young control rats. These findings suggest that L-carnitine improves the activities of mitochondrial enzymes, increases the electron flow through the electron transport chain, and improves reducing equivalence, thereby improves energy status in aged rats.
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PMID:Supplementation of L-carnitine improves mitochondrial enzymes in heart and skeletal muscle of aged rats. 1584 73

Mitochondrial content of skeletal muscle varies among fiber types, and changes in complex ways during aging. We evaluated the regulatory origins of differences in mitochondrial content among muscles of varied fiber type in F344xBNF1 rats, and how these regulatory patterns are altered with aging. In adult (12 month) animals we found that units citrate synthase (CS)/g tissue, a marker for mitochondrial content, varied approximately 3-fold among 10 skeletal muscles. Stoichiometric relationships between CS and isocitrate dehydrogenase, aconitase, and cytochrome c oxidase were generally preserved across fiber types. Among the 10 muscles of adult rats, CS content correlated with nuclear content (R2= 0.36). Muscles differed widely in CS messenger RNA (mRNA)/DNA (an index of variation in transcriptional regulations) and units CS/CS mRNA (an index of variation in posttranscriptional regulations). All muscles of aged rats (35 months) showed an increase in mg DNA/g, suggestive of atrophy. Age-dependent declines in units CS/DNA were accompanied by reductions in CS mRNA/DNA and/or units CS/CS mRNA, depending on muscle fiber type. Thus, declines in units CS/DNA with age appeared to be due to transcriptional as well as translational variations. Differences in mitochondrial content among muscle fiber types and age groups may arise from variations in nuclear content and posttranscriptional processes, as well as transcriptional regulation.
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PMID:Regulation of skeletal muscle mitochondrial content during aging. 1645 89

Studies with the seeds of soybean, navy bean, pea, and peanut were made to determine the extent of leakage of intracellular enzymes during imbition. Embryos with intact testae from all four species were found to leak detectable activities of either intracellular enzymes of the cytosol (glucose-6-phosphate dehydrogenase) or enzymes found in both the cytosol and organelles (malate dehydrogenase, glutamate dehydrogenase, glutamate oxaloacetate transaminase, and NADP-isocitrate dehydrogenase) after 6 hours imbition at 25 C. Pea and peanut embryos with testae leaked considerably lower levels of activity for these enzymes than did those of soybean and bean. Leakage of mitochondrial marker enzymes (fumarase, cytochrome c oxidase, and adenylate kinase) was not detected from embryos with testae, suggesting that a differential diffusion of intracellular components out of cells occurred. Soybean and bean embryos without testae leaked high, and proportionally (per cent dry seed basis) similar, levels of all cytosol, cytosol-organelle, and mitochondrial marker enzymes and protein during imbibition, indicating that cell membranes were not differential to leakage and that they had ruptured. Pea and peanut embryos without testae leaked detectable activities of all cytosol and cytosol-organelle enzymes, although fumarase was the only detectable mitochondrial marker enzyme leaked, suggesting that some degree of differential leakage may have occurred in these species. The outermost layers of embryo cells of seeds without testae of all four species absorbed and sequestered the nonpermeating pigment Evan's blue after 5 to 15 minutes imbibition, indicating that membranes had ruptured. This occurred to a much lesser extent in seeds with intact testae. Both soybean and bean embryos without testae were observed to disintegrate during imbibition, whereas those of pea and peanut did not. These data indicate that seeds of certain legumes are susceptible to cellular rupture during imbibition when seed coats are damaged or missing.
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PMID:Role of the testa in preventing cellular rupture during imbibition of legume seeds. 1666 92

During the period of most active leaf expansion, the foliar dark respiration rate of soybeans (Glycine max cv Williams), grown for 2 weeks in 1000 microliters CO(2) per liter air, was 1.45 milligrams CO(2) evolved per hour leaf density thickness, and this was twice the rate displayed by leaves of control plants (350 microliters CO(2) per liter air). There was a higher foliar nonstructural carbohydrate level (e.g. sucrose and starch) in the CO(2) enriched compared with CO(2) normal plants. For example, leaves of enriched plants displayed levels of nonstructural carbohydrate equivalent to 174 milligrams glucose per gram dry weight compared to the 84 milligrams glucose per gram dry weight found in control plant leaves. As the leaves of CO(2) enriched plants approached full expansion, both the foliar respiration rate and carbohydrate content of the CO(2) enriched leaves decreased until they were equivalent with those same parameters in the leaves of control plants. A strong positive correlation between respiration rate and carbohydrate content was seen in high CO(2) adapted plants, but not in the control plants.Mitochondria, isolated simultaneously from the leaves of CO(2) enriched and control plants, showed no difference in NADH or malate-glutamate dependent O(2) uptake, and there were no observed differences in the specific activities of NAD(+) linked isocitrate dehydrogenase and cytochrome c oxidase. Since the mitochondrial O(2) uptake and total enzyme activities were not greater in young enriched leaves, the increase in leaf respiration rate was not caused by metabolic adaptations in the leaf mitochondria as a response to long term CO(2) enrichment. It was concluded, that the higher respiration rate in the enriched plant's foliage was attributable, in part, to a higher carbohydrate status.
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PMID:Effects of CO(2) Enrichment and Carbohydrate Content on the Dark Respiration of Soybeans. 1666 73

A method for isolating intact chloroplasts from Chlamydomonas reinhardtii F-60 was developed from the Klein, Chen, Gibbs, Platt-Aloia procedure ([1983] Plant Physiol 72: 481-487). Protoplasts, generated by treatment with autolysine, were lysed with a solution of digitonin and fractionated on Percoll step gradients. The chloroplasts were assessed to be 90% intact (ferricyanide assay) and free from cytoplasmic contamination (NADP isocitrate dehydrogenase activity) and to range from 2 to 5% in mitochondrial contamination (cytochrome c oxidase activity). About 25% of the cellular succinate dehydrogenase activity (21.6 micromoles per milligram chlorophyll per hour, as determined enzymically) was placed within the chloroplast. Chloroplastic succinate dehydrogenase had a K(m) for succinate of 0.55 millimolar and was associated with the thylakoidal material derived from the intact chloroplasts. This same thylakoidal material, with an enzymic assay of 21.6 micromoles per milligram chlorophyll per hour was able to initiate a light-dependent uptake of oxygen at a rate of 16.4 micromoles per milligram chlorophyll per hour when supplied with succinate and methyl viologen. Malonate was an apparent competitive inhibitor of this reaction. The succinate dehydrogenase activity present in the chloroplast was sufficient to account for the photoanaerobic rate of acetate dissimilation in H(2) adapted Chlamydomonas (M Gibbs, RP Gfeller, C Chen [1986] Plant Physiol 82: 160-166).
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PMID:Evidence for Chloroplastic Succinate Dehydrogenase Participating in the Chloroplastic Respiratory and Photosynthetic Electron Transport Chains of Chlamydomonas reinhardtii. 1666 55


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