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)

Addition of the cell soluble supernatant fraction to an assay medium containing NADPH generating system, mixed function oxidase substrate and microsomes, resulted in a stimulation of drug metabolism ranging from 12-75%. This stimulation was observed only when the supply of DADPH generating system (isocitric dehydrogenase or glucose 6 phosphate dehydrogenase) was insufficient, leading to a NADPH oxidation rate which was greater than the rate of reduction of NADP+ during the oxidation of a drug. Hence, under our assay conditions, the soluble supernate (SS) is only providing sufficient NADPH generator, and possibly relieving inhibition by the generated NADP+. Finally, microsomal lipid peroxidation measurements under these same conditions indicate negligible to no peroxidation activity in the absence of SS.
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PMID:Explanation of the stimulation of microsomal N-demethylation reactions by soluble supernatant fraction. 0 Jul 45

1. The activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenases were measured in nervous tissue from different animals in an attempt to provide more information about the citric acid cycle in this tissue. In higher animals the activities of citrate synthase are greater than the sum of activities of the isocitrate dehydrogenases, whereas they are similar in nervous tissues from the lower animals. This suggests that in higher animals the isocitrate dehydrogenase reaction is far-removed from equilibrium. If it is assumed that isocitrate dehydrogenase activities provide an indication of the maximum flux through the citric acid cycle, the maximum glycolytic capacity in nervous tissue is considerably greater than that of the cycle. This suggest that glycolysis can provide energy in excess of the aerobic capacity of the tissue. 2. The activities of glutamate dehydrogenase are high in most nervous tissues and the activities of aspartate aminotransferase are high in all nervous tissue investigated. However, the activities of alanine aminotransferase are low in all tissues except the ganglia of the waterbug and cockroach. In these insect tissues, anaerobic glycolysis may result in the formation of alanine rather than lactate.
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PMID:Activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenases, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in nervous tissues from vertebrates and invertebrates. 0 Oct 3

The effect of a single interaperitoneal injection (6 mg/kg body weight) of aflatoxin B1 in propylene glycol on pyridine nucleotides and NDP linked dehydrogenases was studied 24 h after administration of the toxin. The liver showed a decrease in total proteins and pyridine nucleotides though levels of NADP and NADPH remained unchanged. Levels of NAD and NADH were decreased. The activities of hepatic of hwpRIX of hepatic malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICDH) were not altered though ICDH showed an increase when expressed on protein basis. However, there was a significance decrease in the activity of combined HMP dehydrogenases. Adipose tissue showed increased activities of the HMP dehydrogenasess.
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PMID:Effect of aflatoxin B1 on pyridine nucleotides and NADP linked dehydrogenases. 0 75

The oxidative decarboxylation of D-isocitrate catalyzed by NADP-linked isocitrate dehydrogenase is activated by NADPH, the product of the reaction. We analyzed the autocatalytic behavior exhibited by the enzyme during the steady-state kinetics. NADP acts as a competitive inhibitor toward NADPH in the catalytic activation. In a large concentration range of the reduced and oxidized coenzymes, the activity of the enzyme is proportional to the ratio (NADPH)/(NADP). The results are compared with the results of experiments done with other NADP-linked decarboxylating dehydrogenases. Two different models are presented in order to explain the mechanism of action of isocitrate dehydrogenase, according to our data.
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PMID:Nicotinamide adenine dinucleotide phosphate linked isocitrate dehydrogenase. Catalytic activation by the reduced coenzyme product of the reaction. 0 14

Thermostable NADP+ -specific isocitrate dehydrogenase (EC 1.1.1.42) was purified from crude extract of an extremely thermophilic bacterium Thermus flavus AT-62 through DEAE-cellulose column, acetone fractionation, DEAE-Sephadex A-50 column and isoelectric focussing. The enzyme was purified about 500-folds in its specific activity and purity was found to be about 96%. The enzyme was not inactivated after 60 min at 70 degrees C, but 20 and 80% of the activity were lost after 60 min at 80 degrees and 90 degrees C, respectively. Oxalacetate plus glyoxylate (each 1 nM) demonstrated 75% inhibition of the activity in concerted manner. The degree of the inhibition and the affinity of the enzyme for isocitrate and NADP+ decreased with the rise of temperature, especially above 60 degrees C. The activation energy below and above 60 degrees C were 14,500 and 8,000 cal per mole respectively. In CD spectra negative bands at 210 and 220nm were observed and alpha-helix content was calculated to be about 26%. In the course of heating up to 60 degrees practically no change in CD bands are observed, but above 60 degrees the depth of CD bands decreased gradually and remarkably above 80 degrees C. The effect of temperature on kinetic parameters and secondary structures of the enzyme was discussed in relation to the temperature adaptation of the organism.
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PMID:Purification and some properties of NADP+ -specific isocitrate dehydrogenase from an extreme thermophile, Thermus flavus AT-62. 0 66

1. The activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenase were measured in muscles from a large number of animals, in order to provide some indication of the importance of the citric acid cycle in these muscles. According to the differences in enzyme activities, the muscles can be divided into three classes. First, in a number of both vertebrate and invertebrate muscles, the activities of all three enzymes are very low. It is suggested that either the muscles use energy at a very low rate or they rely largely on anaerobic glycolysis for higher rates of energy formation. Second, most insect flight muscles contain high activities of citrate synthase and NAD+-linked isocitrate dehydrogenase, but the activities of the NADP+-linked enzyme are very low. The high activities indicate the dependence of insect flight on energy generated via the citric acid cycle. The flight muscles of the beetles investigated contain high activities of both isocitrate dehydrogenases. Third, other muscles of both vertebrates and invertebrates contain high activities of citrate synthase and NADP+-liniked isocitrate dehydrogenase. Many, if not all, of these muscles are capable of sustained periods of mechanical activity (e.g. heart muscle, pectoral muscles of some birds). Consequently, to support this activity fuel must be supplied continually to the muscle via the circulatory system which, in most animals, also transports oxygen so that energy can be generated by complete oxidation of the fuel. It is suggested that the low activities of NAD+-linked isocitrate dehydrogenase in these muscles may be involved in oxidation of isocitrate in the cycle when the muscles are at rest. 2. A comparison of the maximal activities of the enzymes with the maximal flux through the cycle suggests that, in insect flight muscle, NAD+-linked isocitrate dehydrogenase catalyses a non-equilibrium reaction and citrate synthease catalyses a near-equilibrium reaction. In other muscles, the enzyme-activity data suggest that both citrate synthase and the isocitrate dehydrogenase reactions are near-equilibrium.
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PMID:Activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenase in muscle from vertebrates and invertebrates. 0 36

Mitochondrial preparations isolated from rat ventral prostate were capable of oxidizing isocitrate by way of NADP isocitrate dehydrogenase (NADP-IDH) and NAD-IDH. NAD-IDH activity required ADP for activation. The pH responses for NAD-IDH and NADP-IDH were quite different. The results indicated that two different enzymes were involved in the NAD- and NADP-IDH activities. Indirect evidence indicated that NADPH-NAD transhydrogenase activity might also be involved in the mitochondrial pathway for isocitrate oxidation. NADP-IDH activity was significantly greater than NAD-IDH activity. The oxidation of isocitrate through IDH activity was coupled to the cytochrome system by NADPH- and NADH-cytochrome c reductase activities. Citrate, via isocitrate, oxidation proceeded at a much slower rate suggesting that aconitase activity could be limiting in the oxidation of citrate. In comparison to other tissues, the prostate oxidative enzyme activities are considerably lower. The results suggest that the accumulation of high prostate citrate levels is not due to a limitation imposed by a lack of IDH activity in prostate mitochondria.
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PMID:Mitochondrial isocitrate dehydrogenase and isocitrate oxidation of rat ventral prostate. 1 37

Alkylation at N-1 of the NADP+ adenine ring with 3,4-epoxybutanoic acid gave 1-(2-hydroxy-3-carboxypropyl)-NADP+. Enzymic reduction of the latter, followed by alkaline Dimroth rearrangement and enzymic reoxidation, gave N6-(2-hydroxy-3-carboxypropyl)-NADP+. On the other hand, bromination at C-8 of the NADP+ adenine ring, followed by reaction with the disodium salt of 3-mercaptroproionic acid, gave 8-(2-carboxyethylthio)-NADP+. Carbodimide coupling of the three carboxylic NADP+ derivatives to polyethyleneimine afforded the corresponding macromolecular NADP+ analogues. The carboxylic and the polyethyleneimine derivatives synthesized have been shown to be co-enzymically active with yeast glucose-6-phosphate dehydrogenase, liver glutamate dehydrogenase and yeast aldehyde dehydrogenase. The degree of efficiency relative to NADP+ with the three enzymes ranged from 17% to 100% for the carboxylic derivatives and from 1% to 36% for the polyethyleneimine analogues. On comparing the efficiences with the three enzymes of the N-1 derivatives to the one of the corresponding N6 anc C-8 analogues, the order of activity was N-1 greater than N6 greater C-8, except in the case of the carboxylic compounds with glutamate dehydrogenase, where this order was inverted. None of these modified cofactors were active with pig heart isocitrate dehydrogenase.
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PMID:Preparation of coenzymic activity of soluble polyethyleneimine-bound NADP+ derivatives. 1 99

A protease from Tetrahymena pyriformis inactivated eight of nine commercially available enzymes tested, including lactate deyhdrogenase, isocitrate dehydrogenase (TPN-specific), glucose-6 phosphate dehydrogenase, D-amino acid oxidase, fumarase, pyruvate kinase, hexokinase, and citrate synthase. Urate oxidase was not inactivated. Inactivation occurred at neutral pH, was prevented by inhibitors of the protease, and followed first order kinetics. In those cases tested, inactivation was enhanced by mercaptoethanol. Most of the enzyme-inactivating activity was due to a protease of molecular weight 25,000 that eluted from DEAE-Sephadex at 0.3 M KCl. A second protease of this molecular weight, which was not retained by the gel, inactivated only isocitrate dehydrogenase and D-amino acid oxidase. These two proteases could also be distinguished by temperature and inhibitor sensitivity. Two other protease peaks obtained by DEAE-Sephadex chromatography had little or no no enzyme inactivating activity, while another attacked only D-amino acid oxidase. At least six of the enzymes could be protected from proteolytic inactivation by various ligands. Isocitrates dehydrogenase was protected by isocitrate, TPN, or TPNH, glucose-6-dehydrogenase by glucose-6-P or TPN, pyruvate kinase by phosphoenolypyruvate or ADP, hexokinase by glucose, and fumarase by a mixture of fumarate and malate. Lactate dehdrogenase was not protected by either of its substrates of coenzymes. Citrate synthase was probably protected by oxalacetate. Our data suggest that the protease or proteases discussed here may participate in the inactivation or degradation of a least some enzymes in Tetrahymena. Since the inactivation occurs at neutral pH, this process could be regulated by variations in the cellular levels of substrates, coenzymes, or allosteric regulators resulting form changes in growth conditions or growth state. Such a mechanism would permit the selective retention of enzymes of metabolically active pathways.
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PMID:Enzyme inactivation by a cellular neutral protease: enzyme specificity, effects of ligands on inactivation, and implications for the regulation of enzyme degradation. 1 68

The effect of dietary DL-ethionine and/or DL-methionine on egg laying, and activities of some NAD linked-dehydrogenases and NADPH-producing enzymes in liver of Japanese quail, Coturnix coturnix japonica was investigated. A 0.30% DL-ethionine plus 0.30% DL-methionine supplemented diet reversed partially the egg laying inhibited by the diet with 0.30% DL-ethionine alone. No inhibitory effect on egg laying was observed for the diet supplemented with 0.30% DL-methionine alone. In marked contrast to the decreased activity of L-glycerol 3-phosphate dehydrogenase and malate dehydrogenase, significantly increased activity of lactate dehydrogenase was obtained for quail fed the DL-ethionine, and the DL-ethionine plus the DL-methionine supplemented diet, respectively. No marked changes in activities of these three dehydrogenases were obtained for quail fed the diet supplemented with DL-methionine alone. Although decreased activity was observed for all of the four NADPH-producing enzymes in quail fed the diet supplemented with DL-ethionine alone, the DL-ethionine plus DL-methionine, the smallest decrease was obtained for NADP-isocitrate dehydrogenase. The diet supplemented with DL-methionine alone induced markedly the respective activity of malic enzyme and glucose 6-phosphate dehydrogenase. These results indicate a relatively important function of NADP-isocitrate dehydrogenase for NADPH-production even under DL-ethionine toxicity and suggest complicated relationships between egg production and activities of enzymes associated with carbohydrate and lipid metabolism in quail liver.
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PMID:Effect of dietary DL-ethionine and/or DL-methionine on egg laying and activities of some cytoplasmic NAD linked-dehydrogenases and NADPH-producing enzymes in liver of Japanese quail, Coturnix coturnix japonica. 1


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