Coordinate regulation of the pentose phosphate pathway and of the activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase (Decarboxylating)

1982 ◽  
Vol 27 (6) ◽  
pp. 365-369 ◽  
Author(s):  
C. Pascual ◽  
L. S. Herrera
Keyword(s):  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Coordinate Regulation ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

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.

II. Lokalisation von Enzymen des reduktiven und dem oxydativen Pentosephosphat-Zyklus in den Chloroplasten und Permeabilität der Chloroplasten-Membran gegenüber Metaboliten

1967 ◽  
Vol 22 (11) ◽  
pp. 1200-1215 ◽  
Author(s):  
U. Heber ◽  
U. W. Hallier ◽  
M. A. Hudson ◽  
B. von der Groeben ◽  
R. Ernst ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Enzyme Activities ◽  
Intracellular Localization ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Amino Acid Synthesis ◽  
Phosphogluconate Dehydrogenase ◽  
Chloroplast Membrane ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Isolated Chloroplasts

1. The interrelationship of metabolic activities in chloroplasts and cytoplasm of leaf cells of spinach, sugar beet and Elodea has been investigated. Different methods have been adopted to study the intracellular localization of enzymes and the flow of phosphorylated intermediates across the chloroplast membrane. The flow of substrates was investigated by determining the rates of the conversion of substrates added to aqueously isolated chloroplasts, prior to and after destruction of the outer chloroplast membrane. The observed differences yielded information as to whether a substrate could traverse the chloroplast membrane.Two methods mere used to investigate the localization of enzymes :a) The percentage distribution of photosynthetic and respiratory enzymes in chloroplasts and cytoplasm was calculated from data on enzyme activities in non-aqueous cell fractions.b) Low levels of enzymes in chloroplasts in the presence of high cytoplasmatic levels were detected by assaying enzyme activities in preparations of aqueously isolated chloroplasts prior to and after ultrasonic destruction of the outer chloroplast membrane.2. If chloroplasts are isolated in aqueous sucrose buffer, their outer membranes act as an efficient barrier against the penetration of NADP, RuDP, GAP and, in some but not all experiments, of FMP and GMP. PGA, DHAP and, probably to a lesser extent, aspartate, ɑ-ketoglutarate, oxaloacetate and FDP can traverse this membrane. Chloroplast membranes are significantly altered when isolated in NaCI-buffer systems and do not correspond to the in vivo situation.3. The conversion of Ri-5-P to RuDP occurs exclusively or nearly exclusively in the chloroplasts indicating that phosphoribulokinase and/or ribosephosphate isomerase are located only there.4. The conversion of Ri-5-P to GAP and SuMP, which is catalyzed by the enzymes ribosephosphate isomerase, xylulosephosphate epimerase and transketolase, proceeds likewise only or at least predominantly in the chloroplasts and not, or only to a small extent, in the cytoplasm.5. The major parts of glucose-6-phosphate dehydrogenase and of 6-phosphogluconate dehydrogenase reside in the cytoplasm. However, a small, but significant, level of these enzymes is to be found also in the chloroplasts. Hexokinase and transaldolase are also present there. Pyruvate kinase and phosphofructokinase appear to be absent from chloroplasts.6. Since, with the presence of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, transaldolase and enzymes of the Calvin cycle, the enzymic machinery of the oxidative pentose phosphate pathway is complete in the chloroplasts, the results suggest that chloroplasts are engaged in the oxidative decomposition of carbohydrates.7. In the dark the oxidative pentose phosphate pathway requires the control of NADPH formation and the transfer of hydrogen across the chloroplast membrane.8. The available data on the intracellular localization of enzymes and on the kinetics of the distribution of labelled intermediates show that the photosynthetic carbon cycle operates exclusively within the chloroplasts. There is nothing to suggest that enzymes of chloroplasts and cytoplasm cooperate in the cyclic regeneration of the carbon acceptor molecule. However, the existence of phosphorylated transport metabolites suggests that secondary reactions of photosynthesis such as sucrose and amino acid synthesis, which proceed, at least in part, outside the chloroplasts, are directly linked with chloroplastic reactions by activated (phosphorylated) intermediates.

The effect of soaking injury in bean seeds on aspects of the oxidative pentose phosphate pathway in embryonic axes

1992 ◽  
Vol 2 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Johan C. Pretorius ◽  
J. G. Chris Small
Keyword(s):  
Pentose Phosphate Pathway ◽  
Causative Factor ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Embryonic Axes ◽  
Phosphogluconate Dehydrogenase ◽  
Saturated Water ◽  
Radicle Emergence ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Seed Coats

AbstractSubmerging Phaseolus vulgaris cv. Top Crop seeds in air-saturated water for 16 h markedly depresses subsequent germination. This is termed soaking injury. Soaking injury does not occur in seeds soaked in CO2-saturated water. Previous studies have shown that soaking injury can be alleviated by drying seeds or removing seed coats. Submergence therefore leads to a situation in bean seeds which is similar to secondary dormancy.As with dormant seeds, C6/C1 ratios of embryonic axes of seeds soaked in air-saturated water remained high (0.8–1.0) during and after soaking. This was paralleled by low activities of glucose-6-phosphate dehydrogenase (EC.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44). In axes of seeds soaked in CO2-saturated water and in unsoaked seeds C6/C1 ratios declined steadily during soaking/imbibition and reached values of around 0.3 after germination. Slight increases ofglucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities occurred in the pre-germination phase. This was followed by a massive increase after radicle emergence. Synthesis of the plastid isoenzymes was a post-germinative event.It appears that soaking injury depresses protein synthesis. Lack of oxidative pentose phosphate pathway activity appears to be a causative factor in soaking injury.

scholarly journals Activities of Catalase and Pentose Phosphate Pathway Dehydrogenases during Dormancy Release in Nectarine Seed

1990 ◽  
Vol 115 (6) ◽  
pp. 987-990 ◽  
Author(s):  
Hening Hu ◽  
Gary A. Couvillon
Keyword(s):  
Pentose Phosphate Pathway ◽  
Catalase Activity ◽  
Prunus Persica ◽  
Enzymic Activity ◽  
Pentose Phosphate ◽  
Significant Activity ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Thiourea Treatment

The activities of catalase and of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH), the two key enzymes in the pentose phosphate pathway (ppp), were measured in the seeds of Prunus persica (L.) Batsch var. nectarina Maxim `Nectarine 7'. The seeds were subjected to three imbibition treatments: 1) continuous 24C; 2) continuous 4C; and 3) application of thiourea (TU)/gibberellic acid (GA) at various concentrations to seed held at 24C then subsequently chilled at 4C. Treatments of continuous 24 or 4C indicated that catalase, G6PDH, and 6PGDH exhibited significant activity increases only when the seeds obtained germination potential, which occurred in the seeds chilled for 7 weeks at 4C. Seeds held at 24C did not germinate and showed little change with time in G6PDH and 6PGDH activity. There was only a slight increase in catalase activity beginning 3 weeks following treatment initiation and a decrease in activity following 13 weeks of treatment. Thiourea treatment resulted in an inhibition of catalase activity and a stimulation of G6PDH, but had no effect on 6PGDH activity. However, no correlation between enzymic activity and seed germination was found. The results strongly questioned the role of the ppp and catalase activity in dormancy control as previously hypothesized.

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 The pentose phosphate pathway in regenerating skeletal muscle

1978 ◽  
Vol 170 (1) ◽  
pp. 17-22 ◽  
Author(s):  
K R Wagner ◽  
F C Kauffman ◽  
S R Max
Keyword(s):  
Skeletal Muscle ◽  
Pentose Phosphate Pathway ◽  
Actinomycin D ◽  
Pentose Phosphate ◽  
Skeletal Muscle Regeneration ◽  
Oxidative Enzymes ◽  
Muscle Fibres ◽  
Histochemical Analysis ◽  
Phosphogluconate Dehydrogenase ◽  
Glucose 6 Phosphate Dehydrogenase

1. The activities of the oxidative enzymes (glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) and of the non-oxidative enzymes (transaldolase, tranketolase, ribose 5 phosphate isomerase and ribulose 5-phosphate 3-epimerase) of the pentose phosphate pathway were measured at various times during the first 24h of skeletal-muscle regeneration after administration of Marcaine, a mytoxic local anesthetic. 2. The activities of the oxidative enzymes increased after Marcaine injection and rose to 9 times control activities by 24h. 3. The activities of all non-oxidative enzymes were increased after Marcaine administration, but to a much smaller extent than the oxidative enzymes (1.1-1.7-fold). 4. Histochemical analysis localized glucose 6-phosphate dehydrogenase activity within muscle fibres of control and Marcaine-treated muscles. 5. Cycloheximide or actinomycin D prevented the increase in oxidative enzyme activities, suggesting a requirement for synthesis of protein and RNA.

scholarly journals The Pentose Phosphate Pathway and Its Involvement in Cisplatin Resistance

2020 ◽  
Vol 21 (3) ◽  
pp. 937 ◽  
Author(s):  
Isabella Giacomini ◽  
Eugenio Ragazzi ◽  
Gianfranco Pasut ◽  
Monica Montopoli
Keyword(s):  
Cancer Cells ◽  
Pentose Phosphate Pathway ◽  
Molecular Mechanisms ◽  
Cisplatin Resistance ◽  
Combined Treatment ◽  
Pentose Phosphate ◽  
Metabolic Reprogramming ◽  
Phosphogluconate Dehydrogenase ◽  
Cisplatin Sensitivity ◽  
Glucose 6 Phosphate Dehydrogenase

Cisplatin is the first-line treatment for different types of solid tumors, such as ovarian, testicular, bladder, cervical, head and neck, lung, and esophageal cancers. The main problem related to its clinical use is the onset of drug resistance. In the last decades, among the studied molecular mechanisms of cisplatin resistance, metabolic reprogramming has emerged as a possible one. This review focuses on the pentose phosphate pathway (PPP) playing a pivotal role in maintaining the high cell proliferation rate and representing an advantage for cancer cells. In particular, the oxidative branch of PPP plays a role in oxidative stress and seems to be involved in cisplatin resistance. In light of these considerations, it has been demonstrated that overexpression and higher enzymatic activity of different enzymes of both oxidative and non-oxidative branches (such as glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and transketolase) increase cisplatin resistance, and their silencing or combined treatment with cisplatin could restore cisplatin sensitivity. Moreover, drug delivery systems loaded with both PPP inhibitors and cisplatin give the possibility of reaching cancer cells selectively. In conclusion, targeting PPP is becoming a strategy to overcome cisplatin resistance; however, further studies are required to better understand the mechanisms.

scholarly journals The pentose phosphate pathway of glucose metabolism. Measurement of the non-oxidative reactions of the cycle

1968 ◽  
Vol 107 (6) ◽  
pp. 775-791 ◽  
Author(s):  
F. Novello ◽  
Patricia McLean
Keyword(s):  
Pentose Phosphate Pathway ◽  
Coupled System ◽  
Pentose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Tissue Extracts ◽  
Oxidative Reactions ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Rate Limiting ◽  
Made In

Methods for the quantitative determination of ribose 5-phosphate isomerase, ribulose 5-phosphate 3-epimerase, transketolase and transaldolase in tissue extracts are described. The determinations depend on the measurement of glyceraldehyde 3-phosphate by using the coupled system triose phosphate isomerase, α-glycero-phosphate dehydrogenase and NADH. By using additional purified enzymes transketolase, ribose 5-phosphate isomerase and ribulose 5-phosphate epimerase conditions could be arranged so that each enzyme in turn was made rate-limiting in the overall system. Transaldolase was measured with fructose 6-phosphate and erythrose 4-phosphate as substrates, and again glyceraldehyde 3-phosphate was measured by using the same coupled system. Measurements of the activities of the non-oxidative reactions of the pentose phosphate pathway were made in a variety of tissues and the values compared with those of the two oxidative steps catalysed by glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase.

scholarly journals Catalysis of pentose phosphate pathway reactions by cytoplasmic fractions from muscle, uterus and liver of the rat, and the presence of a reduced nicotinamide–adenine dinucleotide phosphate–triose phosphate oxidoreductase in rat muscle

1974 ◽  
Vol 138 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Terry Wood
Keyword(s):  
Pentose Phosphate Pathway ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Pentose Phosphate ◽  
Hexose Monophosphate ◽  
Triose Phosphate ◽  
Phosphogluconate Dehydrogenase ◽  
Rat Muscle ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Glucose 6 Phosphate Dehydrogenase

1. The enzymes of the pentose phosphate pathway were assayed in supernatant fractions from rat muscle, liver and uterus. 2. On incubation of ribose 5-phosphate with uterus and liver supernatants, triose phosphate, sedoheptulose 7-phosphate and hexose monophosphate accumulated. 3. When a muscle supernatant was used, glycerol 3-phosphate instead of triose phosphate appeared and there was a negligible accumulation of hexose monophosphate. 4. Hexose monophosphate production from ribose 5-phosphate was also followed by measuring NADP+ reduction in the presence of an excess of phosphoglucose isomerase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. 5. With a muscle supernatant, NADPH was reoxidized as rapidly as it was formed owing to the presence of a NADPH–triose phosphate oxidoreductase. 6. A modification of the pentose phosphate pathway in skeletal muscle incorporating this enzyme is proposed.

Sign in / Sign up

Export Citation Format

Share Document