scholarly journals NADP-Dependent Isocitrate Dehydrogenase fromArabidopsisRoots Contributes in the Mechanism of Defence against the Nitro-Oxidative Stress Induced by Salinity

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Marina Leterrier ◽  
Juan B. Barroso ◽  
Raquel Valderrama ◽  
José M. Palma ◽  
Francisco J. Corpas
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Superoxide Radical ◽  
Plant Defence ◽  
Maximum Activity ◽  
Nadph Regeneration ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

NADPH regeneration appears to be essential in the mechanism of plant defence against oxidative stress. Plants contain several NADPH-generating dehydrogenases including isocitrate dehydrogenase (NADP-ICDH), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and malic enzyme (ME). InArabidopsisseedlings grown under salinity conditions (100 mM NaCl) the analysis of physiological parameters, antioxidant enzymes (catalase and superoxide dismutase) and content of superoxide radical (O2  ∙−), nitric oxide (NO), and peroxynitrite (ONOO-) indicates a process of nitro-oxidative stress induced by NaCl. Among the analysed NADPH-generating dehydrogenases under salinity conditions, the NADP-ICDH showed the maximum activity mainly attributable to the root NADP-ICDH. Thus, these data provide new insights on the relevance of the NADP-ICDH which could be considered as a second barrier in the mechanism of response against the nitro-oxidative stress generated by salinity.

NADP-linked dehydrogenases in secreted milk

1985 ◽  
Vol 52 (4) ◽  
pp. 501-506 ◽  
Author(s):  
Murray R. Grigor ◽  
Peter E. Hartmann
Keyword(s):  
Mammary Gland ◽  
Lactate Dehydrogenase ◽  
Malate Dehydrogenase ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Prolonged Storage ◽  
Phosphogluconate Dehydrogenase ◽  
The Absolute ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Accurate Reflection

SUMMARYThe activities of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase, malic enzyme, lactate dehydrogenase and malate dehydrogenase have been determined in secreted milk from sows, rats and rabbits. Within each species, although there was considerable variation in the absolute activities of these enzymes, the relative activities were similar to those observed for, or previously published for mammary homogenates. The only exception was milk glucose 6-phosphate dehydrogenase which tended to lose activity upon prolonged storage in the mammary gland. These results suggest that the pattern of milk enzymes can be an accurate reflection of that occurring in the mammary gland.

scholarly journals Enzymes of glucose metabolism in normal mouse pancreatic islets

1970 ◽  
Vol 119 (1) ◽  
pp. 5-15 ◽  
Author(s):  
S. J. H. Ashcroft ◽  
P. J. Randle
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Pyruvate Carboxylase ◽  
Normal Mouse ◽  
Mean Value ◽  
Intact Mouse ◽  
Major Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Total Glucose ◽  
Glucose 6 Phosphate Dehydrogenase

1. Glucose-phosphorylating and glucose 6-phosphatase activities, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADP+-linked isocitrate dehydrogenase, `malic' enzyme and pyruvate carboxylase were assayed in homogenates of normal mouse islets. 2. Two glucose-phosphorylating activities were detected; the major activity had Km 0.075mm for glucose and was inhibited by glucose 6-phosphate (non-competitive with glucose) and mannoheptulose (competitive with glucose). The other (minor) activity had a high Km for glucose (mean value 16mm) and was apparently not inhibited by glucose 6-phosphate. 3. Glucose 6-phosphatase activity was present in amounts comparable with the total glucose-phosphorylating activity, with Km 1mm for glucose 6-phosphate. Glucose was an inhibitor and the inhibition showed mixed kinetics. No inhibition of glucose 6-phosphate hydrolysis was observed with mannose, citrate or tolbutamide. The inhibition by glucose was not reversed by mannoheptulose. 4. 6-Phosphogluconate dehydrogenase had Km values of 2.5 and 21μm for NADP+ and 6-phosphogluconate respectively. 5. Glucose 6-phosphate dehydrogenase had Km values of 4 and 22μm for NADP+ and glucose 6-phosphate. The Km for glucose 6-phosphate was considerably below the intra-islet concentration of glucose 6-phosphate at physiological extracellular glucose concentrations. The enzyme had no apparent requirement for cations. Of a number of possible modifiers of glucose 6-phosphate dehydrogenase, only NADPH was inhibitory. The inhibition by NADPH was competitive with NADP+ and apparently mixed with respect to glucose 6-phosphate. 6. NADP+–isocitrate dehydrogenase was present but the islet homogenate contained little, if any, `malic' enzyme. The presence of pyruvate carboxylase was also demonstrated. 7. The results obtained are discussed with reference to glucose phosphorylation and glucose 6-phosphate oxidation in the intact mouse islet, and the possible nature of the β-cell glucoreceptor mechanism.

scholarly journals Lipid metabolism by rat lung in vitro. Effect of starvation and re-feeding on utilization of [U-14C]glucose by lung slices

1971 ◽  
Vol 124 (2) ◽  
pp. 257-264 ◽  
Author(s):  
Richard W. Scholz ◽  
Rodney A. Rhoades
Keyword(s):  
Fatty Acid ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Total Phospholipid ◽  
Fatty Acid Fraction ◽  
Acid Fraction ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Vitro Effect

1. The incorporation of [U-14C]glucose into several lipid components of lung and liver slices, and the activities of glucose 6-phosphate dehydrogenase (EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), ‘malic’ enzyme (EC 1.1.1.40) and NADP–isocitrate dehydrogenase (EC 1.1.1.42) of the cell cytosol were examined in normal, starved and re-fed rats. 2. Lipogenesis and the activities of these enzymes in liver were decreased markedly in rats starved for 72h. Re-feeding starved rats on a fat-free diet for 72h resulted in the well documented hyperlipogenic response in liver, particularly in its ability to convert glucose into neutral lipid, and increased activities of glucose 6-phosphate dehydrogenase, ‘malic’ enzyme and 6-phosphogluconate dehydrogenase to values approx. 700, 470 and 250% of controls respectively. 3. Approx. 70% of the total label in lung lipids was present in the phospholipid fraction. Hydrolysis of lung phospholipids revealed that lipogenesis from glucose was considerable, with approx. 40% of the total phospholipid radioactivity present in the fatty acid fraction. 4. Incorporation of glucose into total lung lipids was decreased by approx. 40% in lung slices of starved rats and was returned to control values on re-feeding. Although phospholipid synthesis from glucose was decreased in lung slices of starved rats, the decrease proportionally was greater for the fatty acid fraction (approx. 50%) as compared with the glycerol fraction (approx. 25%). 5. The activities of lung glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP–isocitrate dehydrogenase were not affected by the dietary alterations. ‘Malic’ enzyme activity was not detected in lung cytosol preparations. 6. The results are discussed in relation to the surface-active lining layer (surfactant) of the lung.

scholarly journals Development of NADPH-producing pathways in rat heart

1980 ◽  
Vol 186 (3) ◽  
pp. 799-803 ◽  
Author(s):  
A Andrés ◽  
J Satrústegui ◽  
A Machado
Keyword(s):  
Pentose Phosphate Pathway ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Rat Heart ◽  
Pentose Phosphate ◽  
Mitochondrial Enzyme ◽  
Physiological Functions ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Mitochondrial Malic Enzyme

The behaviours of the principal NADPH-producing enzymes (glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, cytoplasmic and mitochondrial ‘malic’ enzyme and NAPD+-dependent isocitrate dehydrogenase) were studied during the development of rat heart and compared with those in brain and liver. 1. The enzymes belonging to the pentose phosphate pathway exhibit lower activities in heart than in other tissues throughout development. 2. The pattern of induction of heart cytoplasmic and mitochondrial ‘malic’ enzymes does not parallel that found in liver. Heart mitochondrial enzyme is slowly induced from birth onwards. 3. NADP+-dependent isocitrate dehydrogenase has similar activities in all tissues in 18-day foetuses. 4. Heart mitochondrial NADP+-dependent isocitrate dehydrogenase is greatly induced in the adult, where it attains a 10-fold higher activity than in liver. 5. The physiological functions of mitochondrial ‘malic’ enzyme and NADP+-dependent isocitrate dehydrogenase are discussed.

EINFLUSS VON CYCLUS UND EXOGENER HORMONZUFUHR AUF STOFFWECHSELVORGÄNGE DES RATTENUTERUS

1967 ◽  
Vol 56 (2) ◽  
pp. 231-243 ◽  
Author(s):  
H. Schmidt ◽  
I. Noack ◽  
H. Walther ◽  
K. D. Voigt
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Leucine Aminopeptidase ◽  
Intraperitoneal Administration ◽  
Exogenous Hormone ◽  
Rat Uterus ◽  
Normal Cycle ◽  
Phosphogluconate Dehydrogenase ◽  
Dna And Rna ◽  
Hormone Administration ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT The first significant increase of weight, RNA and protein was observed in the uterus of spayed rats twelve hours after the intraperitoneal administration of a single dose of 1 μg oestradiol. There was no significant increase of DNA. At the same time the activities of glucose-6-phosphate dehydrogenase, fructose-1,6-diphosphate aldolase, isocitrate dehydrogenase and leucine aminopeptidase had increased significantly. Twentyfour hours after the injection the augmented values began to decline. Three injections of 1 μg oestradiol, given at 24 hour intervals obtained similar changes, the only difference being that these changes were more marked and that a DNA increase was also observed. The augmentation of protein, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and fructose-1,6-diphosphate aldolase content of cells induced by repeated oestradiol injections was inhibited partly by 1 mg progesterone when administered together with the last dose of oestradiol. During the normal oestrus cycle of the rat uterus an increase of uterine weight, DNA and RNA content and also of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and 1,6-diphosphate aldolase activities was observed, whereas isocitrate dehydrogenase, malate dehydrogenase and leucine aminopeptidase did not change significantly. It would appear that the changes after exogenous hormone administration reflect those of the normal cycle as regards both their extent and timing. The importance of these findings in connection with hormone-induced pathways of uterine metabolism is discussed.

TPNH GENERATION IN THE HUMAN OVARY

1965 ◽  
Vol 49 (1) ◽  
pp. 58-64 ◽  
Author(s):  
M. H. Nielson ◽  
J. C. Warren
Keyword(s):  
Life Cycle ◽  
Corpus Luteum ◽  
Malate Dehydrogenase ◽  
Isocitrate Dehydrogenase ◽  
Relative Activity ◽  
Human Ovary ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT The endogenous activities of four major supernatant enzymes which produce TPNH (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase) were quantitated in both normal and pathologic human ovarian tissues. The atrophic ovary demonstrated the lowest relative activity of the pentose shunt dehydrogenases, whereas luteinized tissues displayed the highest. During the course of its life cycle, the corpus luteum of the nonpregnant female displayed a progressive rise in isocitrate dehydrogenase and a concomitant fall in glucose-6-phosphate dehydrogenase activities. The corpus luteum of pregnancy, studied at term, demonstrated the highest levels of activity of all the four enzymes quantitated.

scholarly journals Regulation of p-nitroanisole O-demethylation in perfused rat liver. Adenine nucleotide inhibition of NADP+-dependent dehydrogenases and NADPH-cytochrome c reductase

1979 ◽  
Vol 184 (3) ◽  
pp. 675-681 ◽  
Author(s):  
F C Kauffman ◽  
R K Evans ◽  
L A Reinke ◽  
R G Thurman
Keyword(s):  
Cytochrome C ◽  
Isocitrate Dehydrogenase ◽  
Malic Enzyme ◽  
Adenine Nucleotide ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Intracellular Atp ◽  
Nucleotide Inhibition ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Nadph Cytochrome C Reductase

Perfusion of rat livers with 10 mM-fructose or pretreatment of the rat with 6-aminonicotinamide (70 mg/kg) 6 h before perfusion decreased intracellular ATP concentrations and increased the rate of p-nitroanisole O-demethylation. This increase was accompanied by a decrease in the free [NADP+]/[NADPH] ratio calculated from concentrations of substrates assumed to be in near-equilibrium with isocitrate dehydrogenase. After pretreatment with 6-aminonicotinamide the [NADP+]/[NADPH] ratio also declined. Reduction of NADP+ during mixed-function oxidation may be explained by inhibition of of one or more NADPH-generating enzymes. Glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase and “malic” enzyme, partially purified from livers of phenobarbital-treated rats, were inhibited by ATP and ADP. Inhibitor constants of ATP for the four dehydrogenases varied considerably, ranging from 9 micrometer for “malic” enzyme to 1.85 mM for glucose 6-phosphate dehydrogenase. NADPH-cytochrome c reductase was also inhibited by ATP (Ki 2.8 mM) and by ADP (Ki 0.9 mM), but not by AMP. Concentrations of ATP and ADP that inhibited glucose 6-phosphate dehydrogenase and the reductase were comparable with concentrations in the intact liver. Thus agents that lower intracellular ATP may accelerate rates of mixed-function oxidation by a concerted mechanism involving deinhibition of NADPH-cytochrome c reductase and one or more NADPH-generating enzymes.

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