scholarly journals Alterations in nicotinamide and adenine nucleotide systems during mixed-function oxidation of p-nitroanisole in perfused livers from normal and phenobarbital-treated rats

1977 ◽  
Vol 166 (3) ◽  
pp. 583-592 ◽  
Author(s):  
Frederick C. Kauffman ◽  
Roxanne K. Evans ◽  
Ronald G. Thurman
Keyword(s):  
Malic Enzyme ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Tricarboxylic Acid Cycle ◽  
Pentose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Oxidation Reduction ◽  
Fructose 1,6 Bisphosphate ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Glucose 6 Phosphate Dehydrogenase

The contents of adenine nucleotides as well as steady-state concentrations of a number of glycolytic, pentose phosphate-pathway and tricarboxylic acid-cycle intermediates were measured in extracts of livers from normal and phenobarbital-treated rats that were perfused with p-nitroanisole. Metabolites were measured in livers that were freeze-clamped during periods of maximal rates of drug metabolism. Treatment of rats with phenobarbital increased rates of p-nitroanisole O-demethylation approx. fivefold. The concentrations of lactate, xylulose 5-phosphate and ribulose 5-phosphate were increased by phenobarbital treatment, whereas that of fructose 1,6-bisphosphate declined. Perfusion of livers with p-nitroanisole produced significant increases in 6-phosphogluconate and ribulose 5-phosphate in livers from phenobarbital-treated rats, but not in livers from control rats. Treatment of rats with phenobarbital caused [NADP+]/[NADPH] to change in the direction of more oxidation, as calculated from measured concentrations of 6-phosphogluconate and ribulose 5-phosphate; however, the [NADP+]/[NADPH] ratio calculated from ‘malic’ enzyme was not changed. Additions of p-nitroanisole produced a reduction of NADP+ as calculated from 6-phosphogluconate dehydrogenase activity, but did not alter the [NADP+]/[NADPH] ratio calculated from substrates assumed to be in equilibrium with ‘malic’ enzyme. Activities of both glucose 6-phosphate dehydrogenase and ‘malic’ enzyme were increased by phenobarbital treatment. NAD+ became more reduced as a result of phenobarbital treatment; however, perfusion of livers with p-nitroanisole did not cause a change in the oxidation–reduction state of this nucleotide. Concentrations of adenine nucleotides in livers were not altered significantly by treatment of rats with phenobarbital; however, a significant decline in the [ATP]/[ADP] ratio occurred during mixed-function oxidation of p-nitroanisole in livers from phenobarbital-treated rats, but not in livers from normal rats. Perfusion of livers with two other substrates for mixed-function oxidation, hexobarbital and aminopyrine, produced an increase in the [NADP+]/[NADPH] ratio calculated from ‘malic’ enzyme. In contrast with livers perfused with p-nitroanisole, there was no significant change in adenine nucleotides in livers exposed to hexobarbital or aminopyrine. Addition of 2,4-dinitrophenol (25μm) to the perfusate containing aminopyrine decreased the [ATP]/[ADP] ratio and tended to prevent the oxidation of NADPH observed with aminopyrine alone. Thus in the presence of an uncoupler of oxidative phosphorylation, NADPH generation may exceed its utilization via mixed-function oxidation.

The possible role of some enzymes in sclerotia formation in Aspergillus ochraceus

1983 ◽  
Vol 29 (6) ◽  
pp. 718-723 ◽  
Author(s):  
Nachman Paster ◽  
Ilan Chet
Keyword(s):  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Pentose Phosphate ◽  
Aspergillus Ochraceus ◽  
Phosphogluconate Dehydrogenase ◽  
Cycle Plays ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
The Glyoxylate Cycle

The role of some enzymes in sclerotia production by Aspergillus ochraceus was studied using a sclerotia-producing strain grown under conditions in which sclerotia production was either favoured or inhibited. In addition, a mutant strain incapable of producing sclerotia was used. No significant differences in patterns of soluble proteins, polyphenol oxidase, and esterases could be detected electrophoretically by gel electrophoresis, while the peroxidase pattern of both the sclerotia-producing strain and the mutant showed three bands as compared with two bands that appeared when sclerotia formation was inhibited. The activities of the tricarboxylic acid cycle enzymes, malate dehydrogenase and succinate dehydrogenase, and those of the pentose-phosphate pathway, glucose-6 phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, were almost identical in sclerotia- and nonsclerotia-producing mycelia. The activities of isocitrate lyase and malate synthetase, key enzymes of the glyoxylate cycle, and that of glyoxylate dehydrogenase which is related to this cycle were significantly reduced when sclerotia formation was inhibited either by methionine or by high levels of CO2. It is suggested that the glyoxylate cycle plays an important role in sclerotia formation in the fungus.

scholarly journals Phosphonomethyl analogues of hexose phosphates

1976 ◽  
Vol 155 (2) ◽  
pp. 433-441 ◽  
Author(s):  
D Webster ◽  
W. R Jondorf ◽  
H B. F. Dixon
Keyword(s):  
Pentose Phosphate ◽  
Phosphate Group ◽  
Phosphogluconate Dehydrogenase ◽  
Fructose 1,6 Bisphosphatase ◽  
Pentose Phosphate Pathways ◽  
Fructose 1,6 Bisphosphate ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Hexose Phosphates

The analogue of fructose 1,6-bisphosphate in which the phosphate group, -O-PO3H2, on C-6 is replaced by the phosphonomethyl group, -CH2-PO3H2, was made enzymically from the corresponding analogue of 3-phosphoglycerate. It was a substrate for aldolase, which was used to form it, but not for fructose 1,6-bisphosphatase. It was hydrolysed chemically to yield the corresponding analogue of fructose 6-phosphate [i.e. 6-deoxy-6-(phosphonomethyl)-D-fructose, or, more strictly, 6,7-dideoxy-7-phosphono-D-arabino-2-heptulose]. This proved to be a substrate for the sequential actions of glucose 6-phosphate isomerase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Thus seven out of the nine enzymes of the glycolytic and pentose phosphate pathways so far tested catalyse the reactions of the phosphonomethyl isosteres of their substrates.

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.

scholarly journals Metabolic phases during the development of granulation tissue

1967 ◽  
Vol 105 (1) ◽  
pp. 333-341 ◽  
Author(s):  
Kirsti Lampiaho ◽  
E. Kulonen
Keyword(s):  
Granulation Tissue ◽  
Collagen Synthesis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Short Period ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Observation Period

1. The metabolism of incubated slices of sponge-induced granulation tissue, harvested 4–90 days after the implantation, was studied with special reference to the capacity of collagen synthesis and to the energy metabolism. Data are also given on the nucleic acid contents during the observation period. Three metabolic phases were evident. 2. The viability of the slices for the synthesis of collagen was studied in various conditions. Freezing and homogenization destroyed the capacity of the tissue to incorporate proline into collagen. 3. Consumption of oxygen reached the maximum at 30–40 days. There was evidence that the pentose phosphate cycle was important, especially during the phases of the proliferation and the involution. The formation of lactic acid was maximal at about 20 days. 4. The capacity to incorporate proline into collagen hydroxyproline in vitro was limited to a relatively short period at 10–30 days. 5. The synthesis of collagen was dependent on the supply of oxygen and glucose, which latter could be replaced in the incubation medium by other monosaccharides but not by the metabolites of glucose or tricarboxylic acid-cycle intermediates.

Analysis of isozymes related to energy metabolism of adult Tegillarca granosa

2007 ◽  
Vol 4 (2) ◽  
pp. 163-166
Author(s):  
Su Xiu-Rong ◽  
Lv Zhen-Ming ◽  
Li Tai-Wu ◽  
Liu Zhi-Ming ◽  
Paul K. Chien
Keyword(s):  
Energy Metabolism ◽  
Malic Enzyme ◽  
Energy Supply ◽  
Anaerobic Metabolism ◽  
Polyacrylamide Gel Electrophoresis ◽  
Pentose Phosphate ◽  
Considerable Proportion ◽  
Tegillarca Granosa ◽  
Phosphogluconate Dehydrogenase ◽  
Auxiliary Role

AbstractThe isozymes of 10 enzymes connected with energy metabolism in Tegillarca granosa were analysed by vertical polyacrylamide gel electrophoresis. Esterase and α-amylase are enzymes related to energy intake, their activities were high in the digestive gland. Malate dehydrogenase, malic enzyme, isocitrate dehydrogenase, succinate dehydrogenase, alcohol dehydrogenase, lactate dehydrogenase, 6-phosphogluconate dehydrogenase (G-6-PDH) and adenosine triphosphatase (ATPase) are enzymes related to energy metabolism. The main energy supply of T. granosa comes from aerobic respiration; anaerobic metabolism and the pentose phosphate pathway take an auxiliary role in energy metabolism. The high activity of G-6-PDH in T. granosa might mean a considerable proportion of carbohydrates metabolized through this pathway. This reaction could provide abundant NADP for metabolism in T. granosa. Compared with other shellfish, T. granosa had lower activity of ATPase, which might have some relationship with the amnicolous life and low motility of this animal.

scholarly journals Glucose metabolism and its regulation in pieces of perirenal adipose tissue from foetal lambs

1983 ◽  
Vol 210 (3) ◽  
pp. 677-683 ◽  
Author(s):  
J P Robertson ◽  
A Faulkner ◽  
R G Vernon
Keyword(s):  
Adipose Tissue ◽  
Glucose Metabolism ◽  
Pyruvate Dehydrogenase ◽  
Glucose Utilization ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Near Term ◽  
Glucose 6 Phosphate Dehydrogenase

1. The following were measured in pieces of perirenal adipose tissue obtained from foetal lambs at about 120 days of gestation or within 3 days of term, and 9-month-old sheep: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO2 and the proportions contributed by the pentose phosphate cycle, pyruvate dehydrogenase and the tricarboxylic acid cycle; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase and pyruvate dehydrogenase. 2. The total rate of glucose utilization was lower in pieces of adipose tissue from near-term lambs than 120-day foetal lambs and the pattern of glucose metabolism differed, with, for example, a much smaller proportion of glucose carbon being used for fatty acid synthesis, whereas a greater proportion of glucose oxidation occurred via the tricarboxylic acid cycle in the near-term lambs. In general, these differences in glucose metabolism were not associated with differences in the activities of the various enzymes listed above. 3. The rates of glucose utilization per fat-cell by 120-day foetal lambs and 9-month-old sheep were very similar but, again, the proportions metabolized to the various products differed. In particular, there was a smaller proportion of glucose oxidized via the pentose phosphate cycle and a greater proportion oxidized via pyruvate dehydrogenase and the tricarboxylic acid cycle in adipose tissue from foetal lambs. These differences were matched by a lower activity of glucose 6-phosphate dehydrogenase and a higher pyruvate dehydrogenase activity in fat-cells from the foetal lambs.

scholarly journals CcpN Controls Central Carbon Fluxes in Bacillus subtilis

2008 ◽  
Vol 190 (18) ◽  
pp. 6178-6187 ◽  
Author(s):  
Simon Tännler ◽  
Eliane Fischer ◽  
Dominique Le Coq ◽  
Thierry Doan ◽  
Emmanuel Jamet ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Pentose Phosphate ◽  
Growth Defect ◽  
Protein Coding ◽  
Arginine Catabolism ◽  
Futile Cycling ◽  
Mutant Phenotypes ◽  
Tricarboxylic Acid Cycle Intermediates

ABSTRACT The transcriptional regulator CcpN of Bacillus subtilis has been recently characterized as a repressor of two gluconeogenic genes, gapB and pckA, and of a small noncoding regulatory RNA, sr1, involved in arginine catabolism. Deletion of ccpN impairs growth on glucose and strongly alters the distribution of intracellular fluxes, rerouting the main glucose catabolism from glycolysis to the pentose phosphate (PP) pathway. Using transcriptome analysis, we show that during growth on glucose, gapB and pckA are the only protein-coding genes directly repressed by CcpN. By quantifying intracellular fluxes in deletion mutants, we demonstrate that derepression of pckA under glycolytic condition causes the growth defect observed in the ccpN mutant due to extensive futile cycling through the pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and pyruvate kinase. Beyond ATP dissipation via this cycle, PckA activity causes a drain on tricarboxylic acid cycle intermediates, which we show to be the main reason for the reduced growth of a ccpN mutant. The high flux through the PP pathway in the ccpN mutant is modulated by the flux through the alternative glyceraldehyde-3-phosphate dehydrogenases, GapA and GapB. Strongly increased concentrations of intermediates in upper glycolysis indicate that GapB overexpression causes a metabolic jamming of this pathway and, consequently, increases the relative flux through the PP pathway. In contrast, derepression of sr1, the third known target of CcpN, plays only a marginal role in ccpN mutant phenotypes.

Comparison of glycolytic, pentose phosphate pathway, glyoxylate shunt, Krebs' cycle enzymes in Ganeo tigrinum parasitizing hibernating and non-hibernating Rana cyanophlyctis and R. tigrina

1983 ◽  
Vol 57 (1) ◽  
pp. 59-68 ◽  
Author(s):  
P. N. Sharma ◽  
Sushila Mandawat
Keyword(s):  
Isocitrate Lyase ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Glyoxylate Shunt ◽  
Strong Activity ◽  
Key Enzymes ◽  
Phosphogluconate Dehydrogenase ◽  
Weak Activity ◽  
Krebs Cycle Enzymes ◽  
Glucose 6 Phosphate Dehydrogenase

AbstractThe histochemical site and distribution of hexokinase, glycogen phosphorylase (GP Rylase), lactate dehydrogenase (LDH) (key enzymes of glycolysis), glucose-6-phosphate dehydrogenase (GPD) and 6-phosphogluconate dehydrogenase (6PGD) (pentose phosphate shunt enzymes), isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and α-ketoglutarate dehydrogenase (α-KDH) (key enzymes of Krebs' cycle), malate synthetase (MS) and isocitrate lyase (IL) (enzymes of glyoxylate shunt) in various tissues of Ganeo tigrinum from hibernating and non-hibernating Rana cyanophlyctis and R. tigrina were studied. Differences in their intensities were revealed. Weak activity of GP Rylase and strong activity of hexokinase in flukes from non-hibernating hosts indicates that they utilize glucose through glycolysis for energy turnover. Intense GP Rylase and weak hexokinase activity in worms from hibernating hosts indicates the utilization of glycogen. Strong activity of IDH, SDH, MDH, α-KGD, MS and IL was demonstrable in the tissues of flukes from non-hibernating hosts, suggesting that Krebs' cycle and glyoxylate shunt, respectively, were operating. Tissues of the fluke from hibernating hosts, on the other hand, displayed positive activity only for SDH and MDH; no activity for MS and IL, the enzymes of glyoxylate shunt, was observed, The activity of the above enzymes was found to be relatively low in worms from hibernating hosts.

scholarly journals Antioxidant SMe1EC2 modulates pentose phosphate pathway and glutathione-dependent enzyme activities in tissues of aged diabetic rats

2017 ◽  
Vol 10 (4) ◽  
pp. 148-154 ◽  
Author(s):  
Nuray Nuriye Ulusu ◽  
Müslüm Gök ◽  
Arzu Ayşe Sayin Şakul ◽  
Nuray Ari ◽  
Milan Stefek ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Enzyme Activities ◽  
Body Weight Loss ◽  
Diabetic Rats ◽  
Pentose Phosphate ◽  
Aged Rats ◽  
Glutathione S Transferase ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
And Control

Abstract The pentose phosphate pathway and glutathione-associated metabolism are the main antioxidant cellular defense systems. This study investigated the effects of the powerful antioxidant SMe1EC2 (2-ethoxycarbonyl-8-methoxy-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b] indolinium dichloride) on pentose phosphate pathway (PPP) and glutathione-dependent enzyme activities in aged diabetic and aged matched control rats. Diabetes was induced by streptozotocin injection in rats aged 13-15 months. Diabetic and control rats were divided into two subgroups, one untreated and one treated with SMe1EC2 (10 mg/kg/day, orally) for 4 months. SMe1EC2 ameliorated body weight loss, but not hyperglycemia of aged diabetic rats. Diabetes resulted in decreased glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD) and glutathione-S-transferase (GST), yet in unchanged glutathione reductase (GR) in the liver of aged diabetic rats. In the liver of the aged control rats, SMe1EC2 did not affect G6PDH, 6PGDH and GR, but it inhibited GST. SMe1EC2 also failed to affect diabetes-induced decline in 6PGDH, it ameliorated G6PDH but produced further decline in GST in the liver of aged diabetic rats. In the kidney of aged rats, G6PDH and GST were found to be comparable among the groups, but diabetes up-regulated 6PGDH and GR; these alterations were prevented by SMe1EC2. In the heart of aged diabetic rats, while GST remained unchanged, the recorded increase in G6PD, 6PGD, GR was prevented by SMe1EC2. Furthermore, an unchanged GR and remarkable increases in G6PD, 6PGD and GST were found in the lung of the aged diabetic group. These alterations were completely prevented by SMe1EC2. The results suggest that in aged rats SMe1EC2 can ameliorate the response of the kidney, heart and lung but not that of the liver against diabetes-induced glucotoxicity by interfering with the activity of redox network enzymes.

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