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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied the isocitrate dehydrogenase of Tetrahymena pyriformis. This enzyme is able to utilize both NAD and NADP, but kinetic studies suggest that the enzymatic activity with NAD is not of physiological signifance. Some of the factors that might regualte the NADP-dependent isocitrate dehydrogenase were also studied. This enzyme has an absolute requirement for divalent cations; Mg,+ and Mn2+ will serve as cofactors but the latter is more effective than the former. It is known that this enzyme is subject to a concerted inhibition by oxaloacetate and glyoxylate. Either glyoxylate or oxaloacetate alone also are capable of inhibiting the enzyme although higher concentrations are required. We have found concerted inhibition also for the NAD-dependent isocitrate dehydrogenase from rat liver and yeast. The activity of the Tetrahymena pyriformis enzyme is inhibited by NADPH. This inhibition is competitive with NADP. The Ki and Km values are, respectively, 20 micrometers and 18 micrometers.
Mol Cell Biochem 1977 Oct 07
PMID:Isocitrate dehydrogenase of Tetrahymena pyriformis. 2 34

Histochemical observations were made of the activities of nucleosidephosphatases splitting ATP, ADP, IDP, and AMP and exopeptidases splitting l-alanine, l-leucine and l-glycyl-proline in the spleen sinuses of man, mouse, rat, hamster, and rabbit. Of the exopeptidases, only glycylprolyl-naphthylamidase could be proved histochemically, and that only in man and rat. Nucleosidephosphatases showed only traces of activity except in the rabbit where there was highly active AMP-ase, the others being moderately active.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979 Dec
PMID:Comments on spleen sinus enzyme equipment. A histochemical study. 4 57

The activities of isocitrate dehydrogenase (NAD), isocitrate dehydrogenase (NADP) and oxoglutarate dehydrogenase have been investigated in Saccharomyces cerevisiae grown in a variety of aerobic and hypoxic conditions, the latter including oxygen deprivation, high glucose concentration, addition of inhibitors of mitochondrial protein synthesis, respiratory inhibition by azide, and impaired respiration mutants. All hypoxic conditions led to a marked decrease of oxoglutarate dehydrogenase and significant decreases of the two isocitrate dehydrogenases. According to its kinetic properties, the NAD-isocitrate dehydrogenase will not be operative in hypoxia "in vivo". From these and other related facts it is concluded that hypoxic conditions in yeast generally lead to a splitting of the tricarboxylic acid cycle and that glutamate synthesis in these conditions takes place through the coupling of the NADP-linked isocitrate and glutamate dehydrogenases.
Mol Cell Biochem 1975 Feb 28
PMID:Isocitrate dehydrogenases and oxoglutarate dehydrogenase activities of baker's yeast grown in a variety of hypoxic conditions. 109 51

A putative isocitrate dehydrogenase (IDH) cDNA from alfalfa has been cloned and sequenced. The derived amino acid sequence of 433 residues contains the isocitrate and isopropylmalate dehydrogenase signatures, is 63% identical to yeast mitochondrial NADP-IDH and shares high sequence identity with peptides of pig heart NADP-IDH. The sequence contains a potential N-terminal leader with similarities to a thylakoid transit peptide. IDH transcripts and NADP-IDH activity were detected in all alfalfa tissues examined, their levels depending upon the tissue type and its developmental stage. Transcripts and enzymatic activity were not induced on exposure of cell suspension cultures to a fungal elicitor. IDH is encoded by a small gene family in alfalfa.
Plant Mol Biol 1992 Dec
PMID:Molecular characterization and expression of an isocitrate dehydrogenase from alfalfa (Medicago sativa L). 128 35

Biochemical and metabolic data have led to the conclusion that the enzyme phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32) contributes to a critical point of divergence in energy conservation pathways between mammals and nematodes. To facilitate the determination of the molecular basis for host vs parasite differences in PEPCK, we have cloned a cDNA encoding this enzyme from a parasitic nematode of ruminants, Haemonchus contortus. H. contortus PEPCK was cloned by functional complementation of a PEPCK-, malic enzyme- strain of Escherichia coli (E1786) using an egg stage H. contortus cDNA library in lambda ZAPII. Selection was for growth on malate as the sole carbon source (malate+ phenotype). We isolated a plasmid, pPEPCK, which reproducibly confers a malate+ phenotype in E1786. The sequence of the 2.0-kb EcoRI insert of pPEPCK predicts a 612-amino acid protein which shows about 74% similarity to Drosophila melanogaster and chicken PEPCK. Extracts of E1786[pPEPCK], but not E1786, contain IDP- or GDP-dependent PEPCK enzyme activity. Sequence analysis revealed that the open reading frame (ORF) in pPEPCK lacked a 5' initiation codon and was probably expressed as an in-frame fusion protein with beta-galactosidase. A strategy combining library screening with PCR analysis of positive clones led to the identification of a clone encoding 6 additional NH2-terminal amino acids, including a Met, which, by comparison with known PEPCK amino acid sequences, is likely to be the translation initiation site.
Mol Biochem Parasitol 1992 Feb
PMID:Cloning of a cDNA encoding phosphoenolpyruvate carboxykinase from Haemonchus contortus. 174 Oct 16

A rapid switch from a fermentative to a primarily oxidative type of glucose utilization was observed during in vitro differentiation of Trypanosoma brucei STIB348 and EATRO1244 bloodstream to procyclic trypomastigotes. In accordance with previously published reports bloodstream populations produced pyruvate as the major end product of glucose catabolism, together with very small amounts of CO2, succinate and glycerol. During differentiation pyruvate excretion decreased within 48 h to the low levels produced by 28-day procyclic stages. Concomitant with the decline in pyruvate formation, acetate appeared as a new product and the rates of respiratory CO2 increased considerably. The amount of carbon released with these compounds could account for nearly all of the glucose carbon consumed. Rates of glucose utilization and formation of acetate and CO2 in cells differentiated for 48 h were essentially the same as those found in 28-day procyclics. Succinate and glycerol excretion remained low during the entire transformation process, and no significant difference in the pattern and quantities of end products were found between the two trypanosome strains. During trypanosome differentiation the changes in metabolism were associated with marked alterations in enzyme activity levels. Activities of the tricarboxylic acid (TCA) cycle enzymes citrate synthase, isocitrate dehydrogenase (NAD+), succinate dehydrogenase and fumarase were not detectable in bloodstream trypomastigotes but appeared upon differentiation for 24 h. An exception was citrate synthase whose activity was not demonstrable until 48 h postinoculation into culture. After 48 h the majority of the TCA cycle enzyme activities continued to increase steadily until day 28. Pyruvate kinase activity decreased in differentiating cells after 48 h to about 25% of the level found in bloodstream trypomastigotes.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Biochem Parasitol 1991 Mar
PMID:Alterations in Krebs cycle enzyme activities and carbohydrate catabolism in two strains of Trypanosoma brucei during in vitro differentiation of their bloodstream to procyclic stages. 190 88

The in vitro metabolism of [1-13C]glucose by Ascaris suum third and fourth-stage larvae was analyzed under different gas phases using 13C nuclear magnetic resonance spectroscopy (13C-NMR). Third-stage larvae (L3) incubated under a gas phase of 85% N2/5% O2/10% CO2 produced trace amounts of [13C]succinate, and molted to fourth-stage larvae (L4) between days 3 and 4 in vitro. However, they appeared to arrest as L3s when incubated under air, or 85% N2/5% O2/10% CO2 in the presence of 2 mM potassium cyanide, or 95% N2/5% CO2. Day 12 L4 (eight days after molting) incubated under 85% N2/5% O2/10% CO2, or 95% N2/5% CO2, or 94% N2/1% O2/5% CO2, produced succinate, acetate, propionate and the branched-chain fatty acids 2-methylvalerate and 2-methylbutyrate by fermentative pathways characteristic of adult body wall muscle. In contrast, when Day 12 L4 were incubated under air, only trace amounts of these acids were detected in the incubation medium. Thus, L4 are capable of synthesizing end-products typical of the adult even in the presence of oxygen, as long as the CO2 tensions are above 5%. As would be predicted, activities of enzymes involved in aerobic metabolism, including citrate synthase, isocitrate dehydrogenase, and cytochrome oxidase, decreased dramatically as L4s underwent the final ecdysis and matured to the adult stage. More importantly, activities of enzymes typical of anaerobic metabolism, including phosphoenolpyruvate carboxykinase and malic enzyme, were substantially elevated in L3s (over their levels in second-stage larvae), and appeared to have reached their adult levels in L3s prior to the third molt, even though L3s still exhibited cyanide sensitivity. Since L3s and L4s have enzymes involved in both aerobic and anaerobic pathways, it is possible that the L3s contain two populations of mitochondria, one which functions aerobically and a second which functions anaerobically.
Mol Biochem Parasitol 1989 Aug
PMID:Effect of gas phase on carbohydrate metabolism in Ascaris suum larvae. 250 8

The insulin-like growth factor I (IGF-1) mediates the actions of pituitary growth hormone in a variety of tissues. Its receptor (IGF1R) displays considerable structural similarity to the insulin receptor. In humans, the IGF1R gene has been mapped near FES, the cellular counterpart of the feline sarcoma virus transforming gene v-fes, at the q25-q26 region of human chromosome 15 (HSA15). Here, we report the mapping of mouse Igf1r to mouse chromosome 7 (MMU7) by somatic cell hybrid analysis. This result, along with the prior assignment of the loci for mitochondrial isocitrate dehydrogenase and FES to human chromosome 15 and mouse chromosome 7, suggest a conserved autosomal synteny group on the distal long arm of HSA15 and in the center of MMU7.
Somat Cell Mol Genet 1989 Jul
PMID:Insulin-like growth factor I receptor gene is concordant with c-Fes protooncogene and mouse chromosome 7 in somatic cell hybrids. 254 93

In Saccharomyces cerevisiae a nuclear recessive mutation, lpd1, which simultaneously abolishes the activities of lipoamide dehydrogenase, 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase has been identified. Strains carrying this mutation can grow on glucose or poorly on ethanol, but are unable to grow on media with glycerol or acetate as carbon source. The mutation does not prevent the formation of other tricarboxylic acid cycle enzymes such as fumarase, NAD+-linked isocitrate dehydrogenase or succinate-cytochrome c oxidoreductase, but these are produced at about 50%-70% of the wild-type levels. The mutation probably affects the structural gene for lipoamide dehydrogenase since the amount of this enzyme in the cell is subject to a gene dosage effect; heterozygous lpd1 diploids produce half the amount of a homozygous wild-type strain. Moreover, a yeast sequence complementing this mutation when present in the cell on a multicopy plasmid leads to marked overproduction of lipoamide dehydrogenase. Homozygous lpd1 diploids were unable to sporulate indicating that some lipoamide dehydrogenase activity is essential for sporulation to occur on acetate.
Mol Gen Genet 1986 Jul
PMID:A mutation affecting lipoamide dehydrogenase, pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase activities in Saccharomyces cerevisiae. 352 55

The mechanism by which the nephrotoxic S-conjugates S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and S-(1,2-dichlorovinyl)-L-homocysteine (DCVHC) produce toxicity in rat kidney mitochondria was studied by examining their effects on mitochondrial function, structural integrity, and metabolism. Both S-conjugates inhibited succinate-linked state 3 respiration and impaired the ability of mitochondria to retain Ca2+ and to generate a membrane potential; 30-60 min were required for maximal expression of these functional changes. Mitochondrial structure was damaged, as indicated by enhanced polyethylene glycol-induced shrinkage of matrix volume and by leakage of protein and malic dehydrogenase from the matrix; 60-120 min were required for maximal expression of these structural changes. Much shorter incubation times (15-30 min) were required for DCVC and DCVHC to decrease ATP concentrations, to alter the concentrations of several citric acid cycle intermediates, and to inhibit succinate:cytochrome c oxidoreductase and isocitrate dehydrogenase activities. Lipid peroxidation and oxidation of glutathione to glutathione disulfide also occurred. The relative time courses of these pathological changes indicate that the initial effects of DCVC and DCVHC in renal mitochondria are the inhibition of energy metabolism and the oxidation of glutathione. These changes then lead to alterations in mitochondrial function and ultimately to irreversible damage to mitochondrial structure.
Mol Pharmacol 1987 Oct
PMID:Mechanism of S-(1,2-dichlorovinyl)-L-cysteine- and S-(1,2-dichlorovinyl)-L-homocysteine-induced renal mitochondrial toxicity. 367 Feb 84


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