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)

Phosphorylated NADP+-isocitrate dehydrogenase (EC 1.1.1.42) has been purified to electrophoretic homogeneity from in vivo 32P-labeled Escherichia coli. The cells used as the source of phosphorylated enzyme were harvested 1 h after the addition of 5 mCi of [32P]orthophosphoric acid and 25 mM sodium acetate to cultures grown to early stationary phase on a low phosphate medium with limiting glucose. Double immunodiffusion and autoradiography demonstrated immunological identity between the 32P-labeled NADP+-isocitrate dehydrogenase and the enzyme isolated from glucose-grown E. coli. The phosphoenzyme had an apparent subunit molecular weight of 51,000 as determined by denaturing acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, and the radioactivity co-electrophoresed with NADP+-isocitrate dehydrogenase activity when purified enzyme was subjected to nondenaturing gel electrophoresis. [32P]Phosphoserine was identified following partial acid hydrolysis of the purified phosphoenzyme.
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PMID:Purification and properties of phosphorylated isocitrate dehydrogenase of Escherichia coli. 11 96

Ovarian cycle in albino rats was applied to ascertain the problem of the relationship between the salivary and endocrine glands, and also of the extent of participation of individual components of the salivary glands with different functional orientation in the endocrine regulation of individual components of the salivary glands. The content of protein, mucopolysaccharides, DNA, and RNA, the activity of NAD- and NADP-diaphorase, alkaline phosphatase, malate and isocitrate dehydrogenase, alpha-leucine-aminopeptidase was studied. Cytospectrophotometric analysis showed that synchronous changes in the activity of the enzymes under study occurred in all the portions of the salivary glands, depending on the ovarian cycle phases. Of the four successive phases of the cycle the greatest activity of the enzymes and of the protein and mucopolysaccharide content was noted during the proestrus and metaestrus. Different metabolic processes were observed in the salivary ducts in comparison with other parts of the gland; this was apparently connected with peculiarities of the secretion and hormone production.
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PMID:[Quantitative histoenzymologic characteristics of the submaxillary salivary glands of white rats during an ovarian cycle]. 14 76

Two groups of rats were provided simultaneously with a commercial stock diet for a period of 7 days. One group was fed ad libitum (control), and the other was restricted to one-fourth of the daily intake of control animals (semistarved). Body weight declined significantly in semistarved rats whereas body weight of controls increased over the 7-day period. The following were determined in vitro on mitochondria isolated from liver, kidney, and heart tissues of both groups: substrate-stimulated and DNP-uncoupled respiratory rates; specific acivities of the Krebs cycle dehydrogenases, and cytochrome c oxidase. Degradative effects of reduced food intake on mitochondrial function were observed. Uncoupled respiratory rates of liver and kidney mitochondria (using succinate as substrate) and heart mitochondria (using alpha-ketoglutarate and pyruvate) were lower. Also lower were activities of isocitrate dehydrogenase, NADP: isocitrate dehydrogenases, transhydrogenase, succinate dehydrogenase, and cytochrome c oxidase of heart mitochondria, transhdrogenase of liver mitochondria, and isocitrate dehydrogenase and transhydrogenase of kidney mitochondria. Such decreases in enzyme activities under conditions of dietary protein deficiency might have their basis in breakdown rates exceeding synthesis rates or result from partial inactivation of existing enzyme protein. Thus, there is evidence that responses to semistarvation of such parameters of mitochondrial function may differ among various tissues. In addition, liver and kidney citrate levels were lower and heart citrate level higher with semistarvation.
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PMID:Effects of semistarvation on rat liver, kidney, and heart mitochondrial function. 16 2

A soluble NAD+-linked isocitrate dehydrogenase has been isolated from Crithidia fasciculata. The enzyme was purified 128-fold, almost to homogeneity, and was highly specific for NAD+ as the coenzyme. There is also a cytoplasmic NADP+-linked and a mitochondrial isocitrate dehydrogenase in the organism. Studies of the physical and kinetic properties of the soluble NAD+-isocitrate dehydrogenase from this organism showed that it resembled microbial NADP+-isocitrate dehydrogenases in general, all of which are cytoplasmic enzymes. The enzyme appeared not to be related to other NAD+-isocitrate dehydrogenases, which are found in the mitochondria of eukaryotic cells. The molecular weight of the soluble NAD+-isocitrate dehydrogenase was 105,000 which is within the range of the values for microbial NADP+-isocitrate dehydrogenases. Similar to the NADP+-isocitrate dehydrogenase in this organism, the enzyme was inhibited in a concerted manner by glyoxalate plus oxalacetate. Kinetic analysis revealed that Mn2+ was involved in the binding of isocitrate to the enzyme. Inhibition of the NAD+-linked isocitrate dehydrogenase by p-chloromercuribenzoate could be prevented by prior incubation of the enzyme with both Mn2+ and isocitrate; however, neither ion alone conferred protection. Free isocitrate, free Mn2+, and the Mn2+-isocitrate complex could all bind to the enzyme. Four different mechanisms with respect to the binding of isocitrate to the enzyme were tested. Of these, the formation of the active enzyme-Mn2+-isocitrate complex from (a) the random binding of Mn2+, isocitrate, and the Mn2+-isocitrate complex, or (b) the binding of Mn2+-isocitrate with free Mn2+ and isocitrate acting as dead-end competitors were both in agreement with these data.
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PMID:Purification and properties of a soluble nicotinamide adenine dinucleotide-linked isocitrate dehydrogenase from Crithidia fasciculata. 16 46

1. NADP-+-specific isocitrate dehydrogenase [EC 1.1.1.42] was partially purified by about 440-fold from an extreme thermophile, Thermus flavus AT-62. 2. Remarkable thermostability of the enzyme was confirmed. The enzyme was not inactivated after 60 min at 70 degrees, and the activity was lost only slowly at 80 degrees. Above 90 degrees, however, rapid inactivation was observed. 3. The dehydrogenase was susceptible to concerted inhibition by oxaloacetate plus glyoxylate. In the presence of oxaloacetate plus glyoxylate (each 1 mM), 75 percent inhibition was observed. 4. The degree of inhibition of the enzyme by oxaloacetate plus glyoxylate decreased markedly above 60 degrees. The affinity of the enzyme for isocitrate and NADP-+ was also reduced markedly above 60 degrees. The activation energy calculated from Arrhenius plots below and above 60 degrees were 14,500 and 8,000 cal per mole, respectively. These observations suggest a possible conformation change of the enzyme protein at a transition temperature of 60 degrees, and the physiological significance of this in the adaptation of thermophiles to elevated temperatures is discussed.
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PMID:Studies on NADP-+-specific isocitrate dehydrogenase from an extreme thermophile, Thermus flavus AT-62. 16 75

The objective of this investigation was to find out whether vitamin E deficiency, apart from influencing the lipid component of cellular membranes, also influences the protein component. For that purpose a number of membrane-bound enzymes in the liver of the Pekin duckling were histochemically, cytochemically, and biochemically examined. Furthermore, cells, cellular membranes, and protein particles in membranes were morphometrically investigated. Histochemically five membrane-bound enzymes appeared to be stimulated in vitamin E deficiency: 5'-nucleotidase, glucose-6-phosphatase, isocitrate dehydrogenase (NADP), tetrazolium reductase (NADH), and tetrazolium reductase (NADPH). 5'-Nucleotidase and glucose-6-phosphatase were also investigated cytochemically and biochemically. The cytochemical localization of these enzymes was identical in control and vitamin E-deficient ducklings. Biochemically, a stimulation of these two enzymes also could be demonstrated. The increase per milligram of DNA appeared to be largest whereas the increase per milligram of protein, per milligram of phospholipid, and per milligram of RNA was only half of the increase per milligram of DNA. This can be explained by the 30 per cent increase of the cell volume in vitamin E deficiency leading to an increase of protein, phospholipid, and RNA per cell. The thickness of membranes and the diameter of protein particles in membranes were measured in liver parenchymal cells. In vitamin E deficiency the thickness of the outer mitochondrial membrane and the diameter of protein particles in this membrane were smaller whereas the thickness of the endoplasmic reticular membrane was larger. The increase of the activities of mitochondrial and microsomal enzymes and the decrease of the thickness of the outer mitochondrial membrane and of its protein particles are interpreted to be the result of the influence of free radicals on membranes with electron transport functions. The increase of 5'-nucleotidase activity in the plasma membrane is likely to have a different cause; it may be related to the transport of nucleotides across this membrane.
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PMID:Cellular membranes and membrane-bound enzymes in vitamin E deficiency. A histochemical, cytochemical, biochemical, and morphologic study of the liver of the Pekin duckling. 16 37

The effects of two environmental temperatures (T; 16 degrees and 31 degrees), five diet dilutions (D; 0%, 12.5%, 25%, 37.5% and 50%), and five daily treadmill running periods (E; 10 minutes, 40 minutes, 70 minutes, 100 minutes, and 130 minutes) upon enzyme activities of liver and adipose tissue of male rats were observed. Liver enzymes studied were glucose-6-phosphatase (G6Pase), 6-P-gluconate dehydrogenase (6PGD), glucose-6-phosphate dehydrogenase (G6PD), fructose diphosphatase (FDPase), NADP-isocitrate dehydrogenase (ICDH), and malic enzyme (ME). Adipose tissue (epididymal fat) enzymes (6PGD, G6PD, and ME) were studied as well as the in vitro incorporation of the 14C of [U-14C] glucose into liberated 14CO2 and into the triglycerides, free fatty acids, and total lipids by adipose tissue slices. Equations describing regression surfaces for these responses (expressed as units/100 g body weight) could contain significant linear coefficients of the independent variables (T, D, and E), their first order interactions, and quadratic coefficients for D and E. Significnat regression coefficients for activities of liver enzymes associated with increased lipogenesis (6PGD, G6PD, and ME) produced response surfaces with conformations generally concave downward. All enzymes possessed positive and negative linear and quadratic coefficients for D which caused response surfaces to be concave downward with respect to that variable. Also, 6PGD and G6PD (positive linear and negative quadratic coefficients for E) exhibited response surfaces concave downward with respect to E. Additionally, 6PGD showed greater activity at 31 degrees than at 16 degrees while G6PD showed no effect of temperature on activity. Liver ICDH, probably important in supplying reducing equivalents for fatty acid synthesis, evidenced response surfaces almost identical to those for 6PGD. Significant regression coefficients for activity of liver enzymes associated with increased gluconeogenesis (FDPase and G6Pase) produced for FDPase a response surface concave downward with respect to both D and E with greater values at 31 degrees than at 16 degrees; but for G6Pase non-concave surfaces with lesser values at 31 degrees than at 16 degrees. Significant regression coefficients for activities of adipose enzymes associated with increased lipogenesis produced for 6PGD a response surface concave upward due to negative linear and positive quadratic coefficients for both D and E. For G6PD and ME regression surfaces were concave upward with respect to E, but these were modified by positive and negative linear coefficients, respectively, for D. Significant regression coefficients for incorporation of the 14C of glucose into triglycerides and free fatty acids of adipose tissue slices and their production of 14CO2 yielded response surfaces concave upward with respect to E (negative linear and positive quadratic coefficients). In addition, the surface for free fatty acids was concave upward with respect to D. The 14CO2 production was greater at 16 degrees than at 31 degrees...
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PMID:Effects in the rat of environmental temperature, diet dilution, and treadmill running on liver and adipose enzymes and metabolism of 14C-glucose: a multiple regression analysis. 18 37

This study attempted to detect evidence of mitochondrial terminal respiratory components in matrix vesicles isolated from rachitic rat tibial epiphyseal plates. Biochemical assays for cytochrome c oxidase, NAD isocitrate dehydrogenase, NADP isocitrate dehydrogenase and succinate-cytochrome c reductase were negative. Polarimetric determinations revealed that the addition of succinate to matrix vesicles in suspension did not cause any increase in oxygen utilization. Spectrophotometric tracings of deoxycholate-solubilized matrix vesicles showed no characteristic absorption peaks or maxima belonging to any of the cytochrome complex components. Attempts to prepare pyridine hemochromes of cytochrome prosthetic groups from the matrix vesicles were also unsuccessful. The above results indicate that key components of mitochondrial respiratory systems are not detectable in rachitic matrix vesicles. The results are compatible with the interpretation that such vesicles are not derived from mitochondria.
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PMID:Absence of mitochondrial terminal respiratory enzymes in cartilage matrix vesicles. 20 76

This paper reports the time course of development of the intramitochondrial cholesterol side-chain-cleavage activity, cytoplasmic NADP+-dependent isocitric dehydrogenase, malic enzyme and glucose-6-phosphate dehydrogenase during ovarian maturation, using as a model the immature rat ovary stimulated to develop with pharmacological doses of gonadotrophin. These enzymic activities were correlated with increases in ovarian content of DNA, cellular content of adenosin 3':5'-monophosphate, and the levels of plasma progesterone. The plasma progesterone concentrations followed closely the development of the [4-14C]cholesterol side-chain-cleavage which was mimicked by the cytoplasmic isocitric dehydrogenase; both enzymes increased in activity 28 times during the 6 days of this study. There was no correlation between adenosine 3':5'-monophosphate levels and cholesterol side-chain cleavage or progesterone plasma concentrations.
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PMID:Changes in enzyme activities during the artificially stimulated transition from follicular to luteal cell types in rat ovary. 20 54

After a brief exposition to glucose, Thiobacillus acidophilus was isolated from a culture of iron-grown T. ferrooxidans. Physicochemical analysis of its DNA showed a G+C content of 62.9-63.2%. The new isolate grows best at 25-30 degrees C and at pH 3.0. Growth is possible between pH 1.5 and 6.0. Thiobacillus acidophilus is apparently strictly aerobic. Ammonium salts are the only suitable source of nitrogen. The bacterium is a facultative autotroph. In addition to elemental sulfur, it obtains energy from organic compounds such as D-glucose, D-galactose, D-fructose, D-mannitol, D-xylose, D-ribose, D-arabinose, L-arabinose, sucrose, sodium citrate, malic acid,dl-aspartic acid, and dl-glutamic acid. Thiobacillus acidophilus possesses the key enzymes of the tricarboxylic acid (TCA) cycle including NAD-and NADP-linked isocitric dehydrogenase and alpha-ketoglutarate dehydrogenase, and the key enzymes of the hexose monophosphate pathway (glucose-6-phosphate and 6-phosphogluconate dehydrogenase, and fructose 1,6-diphosphate aldolase). NADH oxidase has been found in particulate fraction of extracts. Rhodanese and thiosulfate oxidase have also been detected.
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PMID:Thiobacillus acidophilus sp. nov.; isolation and some physiological characteristics. 23 84


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