Journal articles: 'Enzymes; Pentose phosphate pathway'

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Peleato, Maria Luisa, Teresa Muiño-Blanco, José Alvaro Cebrian Pérez, and Manuel José López-Pérez. "Significance of the Non-Oxidative Pentose Phosphate Pathway in Aspergillus oryzae Grown on Different Carbon Sources." Zeitschrift für Naturforschung C 46, no. 3-4 (April 1, 1991): 223–27. http://dx.doi.org/10.1515/znc-1991-3-411.

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Specific enzyme activities of the non-oxidative pentose phosphate pathway in Aspergillus oryzae mycelia grown on different carbon sources were determined. Mycelia grown on glucose, mannitol and ribose show the highest specific activities, ribose 5-phosphate isomerase being specially very enhanced. Moreover, transketolase, transaldolase, ribose 5-phosphate isomerase and ribulose 5-phosphate 3-epimerase were determined in different developmental stages of mycelia grown on glucose, mannitol and ribose. The non-oxidative pentose phosphate pathway is more active during conidiogenesis, except for ribulose 5-phosphate 3-epimerase, suggesting a fundamental role of this pathway during that stage to supply pentoses for nucleic acids biosynthesis. A general decrease of the enzyme activities was found in sporulated mycelia. Arabinose 5-phosphate was tested as metabolite of the pentose pathway. This pentose phosphate was not converted into hexose phosphates or triose phosphates and inhibits significantly the ribose 5-phosphate utilization, being therefore unappropriate to support the Aspergillus oryzae growth.

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Kunjara, S., M. Sochor, S. A. Ali, A. L. Greenbaum, and P. McLean. "Hepatic phosphoribosyl pyrophosphate concentration. Regulation by the oxidative pentose phosphate pathway and cellular energy status." Biochemical Journal 244, no. 1 (May 15, 1987): 101–8. http://dx.doi.org/10.1042/bj2440101.

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Measurements have been made of the tissue content of phosphoribosyl pyrophosphate (PPRibP) and of a range of metabolic intermediates involved in the energy charge of the cell, the glycolytic and pentose phosphate pathways, and of the activity of the enzymes of the pentose phosphate pathway and of PPRibP synthetase (EC 2.7.6.1) in the livers of normal, diabetic, insulin-treated diabetic and starved rats and in livers of rats previously starved and then re-fed with high-fat or high-carbohydrate diets. Diabetes, starvation and high-fat diet all caused a fall in the hepatic PPRibP content, whereas insulin treatment and high-carbohydrate diet raised the tissue content. A positive correlation was shown between the PPRibP content and ATP, energy charge and the cytosolic [NAD+]/[NADH] quotient. A positive association between the PPRibP content and the flux of glucose through the pentose phosphate pathway and the synthesis of ribose 5-phosphate via the oxidative enzymes of that pathway, including ribose-5-phosphate isomerase (EC 5.3.1.6), was also observed. A negative correlation was found between the ADP, AMP and Pi contents, and no correlation existed between PPRibP content and the enzymes of the non-oxidative branch of the pentose phosphate pathway. There was no correlation between hepatic PPRibP content and the activity of PPRibP synthetase measured in vitro. These results are considered in relation to the control of PPRibP synthetase in the liver in vivo.

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Maugeri, Dante A., Joaquin J. B. Cannata, and Juan-José Cazzulo. "Glucose metabolism in Trypanosoma cruzi." Essays in Biochemistry 51 (October 24, 2011): 15–30. http://dx.doi.org/10.1042/bse0510015.

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The causative agent of Chagas disease, Trypanosoma cruzi, metabolizes glucose through two major pathways: glycolysis and the pentose phosphate pathway. Glucose is taken up via one facilitated transporter and its catabolism by the glycolytic pathway leads to the excretion of reduced products, succinate and l-alanine, even in the presence of oxygen; the first six enzymes are located in a peroxisome-like organelle, the glycosome, and the lack of regulatory controls in hexokinase and phosphofructokinase results in the lack of the Pasteur effect. All of the enzymes of the pentose phosphate pathway are present in the four major stages of the parasite's life cycle, and some of them are possible targets for chemotherapy. The gluconeogenic enzymes phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase are present, but there is no reserve polysaccharide.

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Hanstveit, A. O., and J. Goksøyr. "The Pathway of Glucose Catabolism in Sporocytophaga myxococcoides." Microbiology 81, no. 1 (January 1, 2000): 27–35. http://dx.doi.org/10.1099/00221287-81-1-27.

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The pathway of glucose metabolism in Sporocytophaga myxococcoides was studied by a radiorespirometric technique and assays of enzyme activity in cell-free extracts. The primary catabolic pathways in the organism were examined by measurement of relative rates of 14CO2-production from different carbon atoms of labelled glucose, pyruvic acid and acetic acid. These substrates appeared to be degraded solely by enzymes of the Embden-Meyerhof-Parnas pathway in conjunction with the tricarboxylic acid cycle. The results were confirmed by studies of enzyme activity, which showed a lack of two enzymes, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate dehydrogenase, EC. 1.1.1.49) and 6-phospho-gluconate dehydrogenase [6-phospho-D-gluconate: NADP oxidoreductase (decarboxylating), EC. 1.1.1.44], in the pentose pathway, which indicated a biosynthetic function of the non-oxidative part of this pathway.

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Schaaff-Gerstenschläger, Ine, Thomas Miosga, and Friedrich K. Zimmermann. "Genetics of pentose-phosphate pathway enzymes in Saccharomyces cerevisiae." Bioresource Technology 50, no. 1 (January 1994): 59–64. http://dx.doi.org/10.1016/0960-8524(94)90221-6.

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Fridman, Alla, Arindam Saha, Adriano Chan, Darren E. Casteel, Renate B. Pilz, and Gerry R. Boss. "Cell cycle regulation of purine synthesis by phosphoribosyl pyrophosphate and inorganic phosphate." Biochemical Journal 454, no. 1 (July 26, 2013): 91–99. http://dx.doi.org/10.1042/bj20130153.

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Cells must increase synthesis of purine nucleotides/deoxynucleotides before or during S-phase. We found that rates of purine synthesis via the de novo and salvage pathways increased 5.0- and 3.3-fold respectively, as cells progressed from mid-G1-phase to early S-phase. The increased purine synthesis could be attributed to a 3.2-fold increase in intracellular PRPP (5-phosphoribosyl-α-1-pyrophosphate), a rate-limiting substrate for de novo and salvage purine synthesis. PRPP can be produced by the oxidative and non-oxidative pentose phosphate pathways, and we found a 3.1-fold increase in flow through the non-oxidative pathway, with no change in oxidative pathway activity. Non-oxidative pentose phosphate pathway enzymes showed no change in activity, but PRPP synthetase is regulated by phosphate, and we found that phosphate uptake and total intracellular phosphate concentration increased significantly between mid-G1-phase and early S-phase. Over the same time period, PRPP synthetase activity increased 2.5-fold when assayed in the absence of added phosphate, making enzyme activity dependent on cellular phosphate at the time of extraction. We conclude that purine synthesis increases as cells progress from G1- to S-phase, and that the increase is from heightened PRPP synthetase activity due to increased intracellular phosphate.

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Badolia, Rachit, Dinesh K. A. Ramadurai, E. Dale Abel, Peter Ferrin, Iosif Taleb, Thirupura S. Shankar, Aspasia Thodou Krokidi, et al. "The Role of Nonglycolytic Glucose Metabolism in Myocardial Recovery Upon Mechanical Unloading and Circulatory Support in Chronic Heart Failure." Circulation 142, no. 3 (July 21, 2020): 259–74. http://dx.doi.org/10.1161/circulationaha.119.044452.

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Background: Significant improvements in myocardial structure and function have been reported in some patients with advanced heart failure (termed responders [R]) following left ventricular assist device (LVAD)–induced mechanical unloading. This therapeutic strategy may alter myocardial energy metabolism in a manner that reverses the deleterious metabolic adaptations of the failing heart. Specifically, our previous work demonstrated a post-LVAD dissociation of glycolysis and oxidative-phosphorylation characterized by induction of glycolysis without subsequent increase in pyruvate oxidation through the tricarboxylic acid cycle. The underlying mechanisms responsible for this dissociation are not well understood. We hypothesized that the accumulated glycolytic intermediates are channeled into cardioprotective and repair pathways, such as the pentose-phosphate pathway and 1-carbon metabolism, which may mediate myocardial recovery in R. Methods: We prospectively obtained paired left ventricular apical myocardial tissue from nonfailing donor hearts as well as R and nonresponders at LVAD implantation (pre-LVAD) and transplantation (post-LVAD). We conducted protein expression and metabolite profiling and evaluated mitochondrial structure using electron microscopy. Results: Western blot analysis shows significant increase in rate-limiting enzymes of pentose-phosphate pathway and 1-carbon metabolism in post-LVAD R (post-R) as compared with post-LVAD nonresponders (post-NR). The metabolite levels of these enzyme substrates, such as sedoheptulose-6-phosphate (pentose phosphate pathway) and serine and glycine (1-carbon metabolism) were also decreased in Post-R. Furthermore, post-R had significantly higher reduced nicotinamide adenine dinucleotide phosphate levels, reduced reactive oxygen species levels, improved mitochondrial density, and enhanced glycosylation of the extracellular matrix protein, α-dystroglycan, all consistent with enhanced pentose-phosphate pathway and 1-carbon metabolism that correlated with the observed myocardial recovery. Conclusions: The recovering heart appears to direct glycolytic metabolites into pentose-phosphate pathway and 1-carbon metabolism, which could contribute to cardioprotection by generating reduced nicotinamide adenine dinucleotide phosphate to enhance biosynthesis and by reducing oxidative stress. These findings provide further insights into mechanisms responsible for the beneficial effect of glycolysis induction during the recovery of failing human hearts after mechanical unloading.

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Soderberg, Tim, and Robert C. Alver. "Transaldolase ofMethanocaldococcus jannaschii." Archaea 1, no. 4 (2004): 255–62. http://dx.doi.org/10.1155/2004/608428.

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TheMethanocaldococcus jannaschiigenome contains putative genes for all four nonoxidative pentose phosphate pathway enzymes. Open reading frame (ORF) MJ0960 is a member of themipB/talCfamily of ‘transaldolase-like’ genes, so named because of their similarity to the well-characterized transaldolase B gene family. However, recently, it has been reported that both themipBand thetalCgenes fromEscherichia coliencode novel enzymes with fructose-6-phosphate aldolase activity, not transaldolase activity (Schürmann and Sprenger 2001). The same study reports that other members of themipB/talCfamily appear to encode transaldolases. To confirm the function of MJ0960 and to clarify the presence of a nonoxidative pentose phosphate pathway inM. jannaschii, we have cloned ORF MJ0960 fromM. jannaschiigenomic DNA and purified the recombinant protein. MJ0960 encodes a transaldolase and displays no fructose-6-phosphate aldolase activity. It retained full activity for 4 h at 80 °C, and for 3 weeks at 25 °C.Methanocaldococcus jannaschiitransaldolase has a maximal velocity (Vmax) of 1.0 ± 0.2 µmol min–1mg–1at 25 °C, whereasVmax= 12.0 ± 0.5 µmol min–1mg–1at 50 °C. Apparent Michaelis constants at 50 °C wereKm= 0.65 ± 0.09 mM for fructose-6-phosphate andKm= 27.8 ± 4.3 µM for erythrose-4-phosphate. When ribose-5-phosphate replaced erythrose-4-phosphate as an aldose acceptor,Vmaxdecreased twofold, whereas theKmwas 150-fold higher. The molecular mass of the active enzyme is 271 ± 27 kDa as estimated by gel filtration, whereas the predicted monomer size is 23.96 kDa, suggesting that the native form of the protein is probably a decamer. A readily available source of thermophilic pentose phosphate pathway enzymes including transaldolase may have direct application in enzymatic biohydrogen production.

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Hong, Zhen Quan, and Les Copeland. "Pentose phosphate pathway enzymes in nitrogen-fixing leguminous root nodules." Phytochemistry 29, no. 8 (January 1990): 2437–40. http://dx.doi.org/10.1016/0031-9422(90)85162-9.

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Sprenger, Georg A. "Genetics of pentose-phosphate pathway enzymes ofEscherichia coli K-12." Archives of Microbiology 164, no. 5 (November 1995): 324–30. http://dx.doi.org/10.1007/bf02529978.

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Kelso, T. B., C. R. Shear, and S. R. Max. "Enzymes of glutamine metabolism in inflammation associated with skeletal muscle hypertrophy." American Journal of Physiology-Endocrinology and Metabolism 257, no. 6 (December 1, 1989): E885—E894. http://dx.doi.org/10.1152/ajpendo.1989.257.6.e885.

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Glutamine synthesis and utilization were studied in the plantaris muscle after removal of its functional synergists, the soleus and gastrocnemius muscles. Rat plantaris muscle was compared with unoperated controls at 7, 14, and 30 days after synergist ablation and induction of hypertrophy. Glutamine synthetase activity increased from 6.17 +/- 1.77 to 33.92 +/- 2.23 nmol.h-1.mg protein-1, and glutaminase activities increased from 98.63 +/- 23.05 to 478.70 +/- 64.17 nmol.h-1.mg protein-1 7 days after surgery and remained elevated at 14 and 30 days. Sham-operated controls examined 7 days after surgery did not exhibit significantly increased glutamine synthetase activity. Histological examination revealed a large proliferation of connective tissue cells, as well as cells involved in tissue repair and inflammation; this influx was maximal 1 wk after surgery. The activity of the oxidative enzymes of the pentose phosphate pathway increased from 3.08 +/- 4.31 to 20.86 +/- 1.13 nmol.min-1.mg protein-1 1 wk after surgery. The time course of changes in pentose phosphate pathway enzymes was similar to that of the increases in glutamine synthetase, glutaminase, and cellular infiltration. Increases in muscle wet weight followed a different time course than changes in glutamine synthetase, glutaminase, and pentose phosphate pathway activities. It is concluded that the initial increases in plantaris muscle weight are probably due to edema, connective tissue proliferation, and cells involved in tissue repair and inflammation. The increase in glutamine synthetase activity appears to occur in skeletal muscle, whereas the changes in glutaminase and pentose phosphate pathway activities appear to represent infiltrating inflammatory cells. Furthermore, the increase in glutamine synthetase activity may serve to support the infiltrating cells, which appear to lack substantial capacity for glutamine production. These results represent a functional relationship between skeletal muscle glutamine synthesis and utilization by cells mediating inflammation and connective tissue repair and synthesis.

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Lelevich, S. V. "Comparative feature of the glucose metabolism in liver of the rats under acute alcohol and morphine intoxication." Biomeditsinskaya Khimiya 57, no. 6 (2011): 615–23. http://dx.doi.org/10.18097/pbmc20115706615.

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The comparative analysis effect of acute alcohol and morphine intoxications on rats on hepatic glycolysis and pentose phosphate pathway was done. The dose-dependent inhibitory effect of ethanol on activity of limiting enzymes of these metabolic ways, as well as anaerobic reorientation of glucose metabolism was recognised with the increase of the dose of the intake alcohol. Morfine (10 mg/kg) activated enymes of glycolysis and pentose phosphate pathway, but in contrast to ethanol it did not influence these parameters at the dose 20 or 40 mg/kg.

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Bushau-Sprinkle, Adrienne, Michelle T. Barati, Kenneth B. Gagnon, Syed Jalal Khundmiri, Kathleen Kitterman, Bradford G. Hill, Amanda Sherwood, et al. "NHERF1 Loss Upregulates Enzymes of the Pentose Phosphate Pathway in Kidney Cortex." Antioxidants 9, no. 9 (September 14, 2020): 862. http://dx.doi.org/10.3390/antiox9090862.

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(1) Background: We previously showed Na/H exchange regulatory factor 1 (NHERF1) loss resulted in increased susceptibility to cisplatin nephrotoxicity. NHERF1-deficient cultured proximal tubule cells and proximal tubules from NHERF1 knockout (KO) mice exhibit altered mitochondrial protein expression and poor survival. We hypothesized that NHERF1 loss results in changes in metabolic pathways and/or mitochondrial dysfunction, leading to increased sensitivity to cisplatin nephrotoxicity. (2) Methods: Two to 4-month-old male wildtype (WT) and KO mice were treated with vehicle or cisplatin (20 mg/kg dose IP). After 72 h, kidney cortex homogenates were utilized for metabolic enzyme activities. Non-treated kidneys were used to isolate mitochondria for mitochondrial respiration via the Seahorse XF24 analyzer. Non-treated kidneys were also used for LC-MS analysis to evaluate kidney ATP abundance, and electron microscopy (EM) was utilized to evaluate mitochondrial morphology and number. (3) Results: KO mouse kidneys exhibit significant increases in malic enzyme and glucose-6 phosphate dehydrogenase activity under baseline conditions but in no other gluconeogenic or glycolytic enzymes. NHERF1 loss does not decrease kidney ATP content. Mitochondrial morphology, number, and area appeared normal. Isolated mitochondria function was similar between WT and KO. Conclusions: KO kidneys experience a shift in metabolism to the pentose phosphate pathway, which may sensitize them to the oxidative stress imposed by cisplatin.

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Sprenger, Georg A. "Genetics of pentose-phosphate pathway enzymes of Escherichia coli K-12." Archives of Microbiology 164, no. 5 (November 21, 1995): 324–30. http://dx.doi.org/10.1007/s002030050270.

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Özaslan, Muhammet Serhat, Neslihan Balcı, Yeliz Demir, Mahmut Gürbüz, and Ömer İrfan Küfrevioğlu. "Inhibition effects of some antidepressant drugs on pentose phosphate pathway enzymes." Environmental Toxicology and Pharmacology 72 (November 2019): 103244. http://dx.doi.org/10.1016/j.etap.2019.103244.

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Loureiro, Inês, Joana Faria, Nuno Santarem, Terry K. Smith, Joana Tavares, and Anabela Cordeiro-da-Silva. "Potential Drug Targets in the Pentose Phosphate Pathway of Trypanosomatids." Current Medicinal Chemistry 25, no. 39 (January 17, 2019): 5239–65. http://dx.doi.org/10.2174/0929867325666171206094752.

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The trypanosomatids, Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp, are causative agents of important human diseases such as African sleeping sickness, Chagas’ disease and Leishmaniasis, respectively. The high impact of these diseases on human health and economy worldwide, the unsatisfactory available chemotherapeutic options and the absence of human effective vaccines, strongly justifies the search for new drugs. The pentose phosphate pathway has been proposed to be a viable strategy to defeat several infectious diseases, including those from trypanosomatids, as it includes an oxidative branch, important in the maintenance of cell redox homeostasis, and a non-oxidative branch in which ribose 5-phosphate and erythrose 4-phosphate, precursors of nucleic acids and aromatic amino acids, are produced. This review provides an overview of the available chemotherapeutic options against these diseases and discusses the potential of genetically validated enzymes from the pentose phosphate pathway of trypanosomatids to be explored as potential drug targets.

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Chan, Giek Far, Han Ming Gan, How Lie Ling, and Noor Aini Abdul Rashid. "Genome Sequence of Pichia kudriavzevii M12, a Potential Producer of Bioethanol and Phytase." Eukaryotic Cell 11, no. 10 (October 2012): 1300–1301. http://dx.doi.org/10.1128/ec.00229-12.

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ABSTRACTA draft genome sequence ofPichia kudriavzeviiM12 is presented here. The genome reveals the presence of genes encoding enzymes involved in xylose utilization and the pentose phosphate pathway for bioethanol production. Strain M12 is also a potential producer of phytases, enzymes useful in food processing and agriculture.

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Wong, A. L., and H. J. Willetts. "Polyacrylamide-gel Electrophoresis of Enzymes during Morphogenesis of Sclerotia of Sclerotinia sclerotiorum." Microbiology 81, no. 1 (January 1, 2000): 101–9. http://dx.doi.org/10.1099/00221287-81-1-101.

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Succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (Glu-6-PDH) from Sclerotinia sclerotiorum (Lib.) de Bary were moderately active in submerged mycelium while in non-sclerotial aerial mycelium arylesterase and acid phosphatase were very active. In sclerotial initials, glyceraldehyde-3-phosphate dehydrogenase (Gly-3-PDH) and SDH were at their highest level of activity, Glu-6-PDH and phosphogluconate dehydrogenase (PGDH) were moderately active, laccase activity increased markedly, and tyrosinase was detected for the first time, its activity being moderate. In young compacting sclerotia, the activities of Glu-6-PDH and PGDH increased, Gly-3-PDH and SDH showed lowered activities, and laccase activity decreased. Suppression of the glycolytic Krebs-cycle pathway and the stimulation of the pentose phosphate pathway seem important during the compaction and maturation of sclerotia. Tyrosinase may be involved in sclerotial initiation.

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Jortzik, Esther, Boniface M. Mailu, Janina Preuss, Marina Fischer, Lars Bode, Stefan Rahlfs, and Katja Becker. "Glucose-6-phosphate dehydrogenase–6-phosphogluconolactonase: a unique bifunctional enzyme from Plasmodium falciparum." Biochemical Journal 436, no. 3 (May 27, 2011): 641–50. http://dx.doi.org/10.1042/bj20110170.

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The survival of malaria parasites in human RBCs (red blood cells) depends on the pentose phosphate pathway, both in Plasmodium falciparum and its human host. G6PD (glucose-6-phosphate dehydrogenase) deficiency, the most common human enzyme deficiency, leads to a lack of NADPH in erythrocytes, and protects from malaria. In P. falciparum, G6PD is combined with the second enzyme of the pentose phosphate pathway to create a unique bifunctional enzyme named GluPho (glucose-6-phosphate dehydrogenase–6-phosphogluconolactonase). In the present paper, we report for the first time the cloning, heterologous overexpression, purification and kinetic characterization of both enzymatic activities of full-length PfGluPho (P. falciparum GluPho), and demonstrate striking structural and functional differences with the human enzymes. Detailed kinetic analyses indicate that PfGluPho functions on the basis of a rapid equilibrium random Bi Bi mechanism, where the binding of the second substrate depends on the first substrate. We furthermore show that PfGluPho is inhibited by S-glutathionylation. The availability of recombinant PfGluPho and the major differences to hG6PD (human G6PD) facilitate studies on PfGluPho as an excellent drug target candidate in the search for new antimalarial drugs.

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Tsai, C. Stan, and Q. Chen. "Regulation of D-glucose-6-phosphate dehydrogenase from Schizosaccharomyces pombe." Biochemistry and Cell Biology 76, no. 4 (August 1, 1998): 645–48. http://dx.doi.org/10.1139/o98-023.

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D-Glucose-6-phosphate dehydrogenase is a regulatory enzyme of the oxidative pentose phosphate pathway in Schizasaccharomyces pombe. The enzyme is subject to negative cooperative regulation by D-glucose-6-phosphate as characterized by the Hill coefficient of 0.68 ± 0.04. D-Glyceraldehyde-3-phosphate and D-ribulose-5-phosphate rectify the negative cooperativity as evidenced from a change in the Hill coefficients to 0.98 ± 0.05 and 1.02 ± 0.05, respectively. These pentose phosphate pathway intermediates also inhibit the enzyme competitively with respect to D-glucose-6-phosphate. Thus, D-glucose-6-phosphate dehydrogenase provides an avenue for regulating the partitioning of D-glucose between the redundant branches of the oxidative phosphate pathway in S. pombe.Key words: regulation, yeast, glucose-6-phosphate dehydrogenase.

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Soderberg, Tim. "Biosynthesis of ribose-5-phosphate and erythrose-4-phosphate in archaea: a phylogenetic analysis of archaeal genomes." Archaea 1, no. 5 (2005): 347–52. http://dx.doi.org/10.1155/2005/314760.

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A phylogenetic analysis of the genes encoding enzymes in the pentose phosphate pathway (PPP), the ribulose monophosphate (RuMP) pathway, and the chorismate pathway of aromatic amino acid biosynthesis, employing data from 13 complete archaeal genomes, provides a potential explanation for the enigmatic phylogenetic patterns of the PPP genes in archaea. Genomic and biochemical evidence suggests that three archaeal species (Methanocaldococcus jannaschii,Thermoplasma acidophilumandThermoplasma volcanium) produce ribose-5-phosphate via the nonoxidative PPP (NOPPP), whereas nine species apparently lack an NOPPP but may employ a reverse RuMP pathway for pentose synthesis. One species (Halobacteriumsp. NRC-1) lacks both the NOPPP and the RuMP pathway but may possess a modified oxidative PPP (OPPP), the details of which are not yet known. The presence of transketolase in several archaeal species that are missing the other two NOPPP genes can be explained by the existence of differing requirements for erythrose-4-phosphate (E4P) among archaea: six species use transketolase to make E4P as a precursor to aromatic amino acids, six species apparently have an alternate biosynthetic pathway and may not require the ability to make E4P, and one species (Pyrococcus horikoshii) probably does not synthesize aromatic amino acids at all.

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Dekleva, Michael L., and William R. Strohl. "Biosynthesis of ε-rhodomycinone from glucose by Streptomyces C5 and comparison with intermediary metabolism of other polyketide-producing streptomycetes." Canadian Journal of Microbiology 34, no. 11 (November 1, 1988): 1235–40. http://dx.doi.org/10.1139/m88-217.

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The catabolism of glucose by Streptomyces C5, a producer of anthracycline antibiotics, was investigated to determine the pathways that supply precursors for anthracycline biosynthesis. Carbons for the biosynthesis of ε-rhodomycinone, an anthracycline aglycone, from radiolabelled glucose were derived primarily from the Embden–Meyerhof–Parnas pathway, with a minor contribution from the pentose phosphate pathway. Furthermore, the anthracycline-producing strain, Streptomyces C5, as well as Streptomyces aureofaciens and Streptomyces lividans, strains that produce nonanthracycline polyketide antibiotics, displayed enzyme activities indicative of the Embden–Meyerhof–Parnas and pentose phosphate glycolytic pathways. As determined from labelling patterns, Streptomyces C5 apparently has a complete tricarboxylic acid cycle, but does not have a glyoxylate bypass pathway.

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Alexander, M. A., V. W. Yang, and T. W. Jeffries. "Levels of pentose phosphate pathway enzymes fromCandida shehatae grown in continuous culture." Applied Microbiology and Biotechnology 29, no. 2-3 (September 1988): 282–88. http://dx.doi.org/10.1007/bf01982917.

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TONOUCHI, Naoto, Masakazu SUGIYAMA, and Kenzo YOKOZEKI. "Coenzyme Specificity of Enzymes in the Oxidative Pentose Phosphate Pathway ofGluconobacter oxydans." Bioscience, Biotechnology, and Biochemistry 67, no. 12 (January 2003): 2648–51. http://dx.doi.org/10.1271/bbb.67.2648.

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Stover, Nicholas A., Thomas A. Dixon, and Andre R. O. Cavalcanti. "Multiple Independent Fusions of Glucose-6-Phosphate Dehydrogenase with Enzymes in the Pentose Phosphate Pathway." PLoS ONE 6, no. 8 (August 1, 2011): e22269. http://dx.doi.org/10.1371/journal.pone.0022269.

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Ronimus, Ron S., and Hugh W. Morgan. "Distribution and phylogenies of enzymes of the Embden-Meyerhof-Parnas pathway from archaea and hyperthermophilic bacteria support a gluconeogenic origin of metabolism." Archaea 1, no. 3 (2003): 199–221. http://dx.doi.org/10.1155/2003/162593.

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Enzymes of the gluconeogenic/glycolytic pathway (the Embden-Meyerhof-Parnas (EMP) pathway), the reductive tricarboxylic acid cycle, the reductive pentose phosphate cycle and the Entner-Doudoroff pathway are widely distributed and are often considered to be central to the origins of metabolism. In particular, several enzymes of the lower portion of the EMP pathway (the so-called trunk pathway), including triosephosphate isomerase (TPI; EC 5.3.1.1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12/13), phosphoglycerate kinase (PGK; EC 2.7.2.3) and enolase (EC 4.2.1.11), are extremely well conserved and universally distributed among the three domains of life. In this paper, the distribution of enzymes of gluconeogenesis/glycolysis in hyperthermophiles—microorganisms that many believe represent the least evolved organisms on the planet—is reviewed. In addition, the phylogenies of the trunk pathway enzymes (TPIs, GAPDHs, PGKs and enolases) are examined. The enzymes catalyzing each of the six-carbon transformations in the upper portion of the EMP pathway, with the possible exception of aldolase, are all derived from multiple gene sequence families. In contrast, single sequence families can account for the archaeal and hyperthermophilic bacterial enzyme activities of the lower portion of the EMP pathway. The universal distribution of the trunk pathway enzymes, in combination with their phylogenies, supports the notion that the EMP pathway evolved in the direction of gluconeogenesis, i.e., from the bottom up.

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Cordeiro, Artur T. "NADPH Producing Enzymes as Promising Drug Targets for Chagas Disease." Current Medicinal Chemistry 26, no. 36 (December 13, 2019): 6564–71. http://dx.doi.org/10.2174/0929867325666181009152844.

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Reduced Nicotinamide Adenine Dinucleotide Phosphate (NADPH) is a cofactor used in different anabolic reactions, such as lipid and nucleic acid synthesis, and for oxidative stress defense. NADPH is essential for parasite growth and viability. In trypanosomatid parasites, NADPH is supplied by the oxidative branch of the pentose phosphate pathway and by enzymes associated with the citric acid cycle. The present article will review recent achievements that suggest glucose-6-phosphate dehydrogenase and the cytosolic isoform of the malic enzyme as promising drug targets for the discovery of new drugs against Trypanosoma cruzi and T. brucei. Topics involving an alternative strategy in accelerating T. cruzi drug-target validation and the concept of drug-target classification will also be revisited.

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Frederiks, Wilma M., Intan P. E. D. Kümmerlin, Klazina S. Bosch, Heleen Vreeling-Sindelárová, Ard Jonker, and Cornelis J. F. Van Noorden. "NADPH Production by the Pentose Phosphate Pathway in the Zona Fasciculata of Rat Adrenal Gland." Journal of Histochemistry & Cytochemistry 55, no. 9 (May 3, 2007): 975–80. http://dx.doi.org/10.1369/jhc.7a7222.2007.

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Biosynthesis of steroid hormones in the cortex of the adrenal gland takes place in smooth endoplasmic reticulum and mitochondria and requires NADPH. Four enzymes produce NADPH: glucose-6-phosphate dehydrogenase (G6PD), the key regulatory enzyme of the pentose phosphate pathway, phosphogluconate dehydrogenase (PGD), the third enzyme of that pathway, malate dehydrogenase (MDH), and isocitrate dehydrogenase (ICDH). However, the contribution of each enzyme to NADPH production in the cortex of adrenal gland has not been established. Therefore, activity of G6PD, PGD, MDH, and ICDH was localized and quantified in rat adrenocortical tissue using metabolic mapping, image analysis, and electron microscopy. The four enzymes have similar localization patterns in adrenal gland with highest activities in the zona fasciculata of the cortex. G6PD activity was strongest, PGD, MDH, and ICDH activity was ∼60%, 15%, and 7% of G6PD activity, respectively. The Km value of G6PD for glucose-6-phosphate was two times higher than the Km value of PGD for phosphogluconate. As a consequence, virtual flux rates through G6PD and PGD are largely similar. It is concluded that G6PD and PGD provide the major part of NADPH in adrenocortical cells. Their activity is localized in the cytoplasm associated with free ribosomes and membranes of the smooth endoplasmic reticulum, indicating that NADPH-demanding processes related to biosynthesis of steroid hormones take place at these sites. Complete inhibition of G6PD by androsterones suggests that there is feedback regulation of steroid hormone biosynthesis via G6PD.

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Giacomini, Isabella, Eugenio Ragazzi, Gianfranco Pasut, and Monica Montopoli. "The Pentose Phosphate Pathway and Its Involvement in Cisplatin Resistance." International Journal of Molecular Sciences 21, no. 3 (January 31, 2020): 937. http://dx.doi.org/10.3390/ijms21030937.

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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.

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Kim, Soo Rin, Haiqing Xu, Anastashia Lesmana, Uros Kuzmanovic, Matthew Au, Clarissa Florencia, Eun Joong Oh, Guochang Zhang, Kyoung Heon Kim, and Yong-Su Jin. "Deletion ofPHO13, Encoding Haloacid Dehalogenase Type IIA Phosphatase, Results in Upregulation of the Pentose Phosphate Pathway in Saccharomyces cerevisiae." Applied and Environmental Microbiology 81, no. 5 (December 19, 2014): 1601–9. http://dx.doi.org/10.1128/aem.03474-14.

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ABSTRACTThe haloacid dehalogenase (HAD) superfamily is one of the largest enzyme families, consisting mainly of phosphatases. Although intracellular phosphate plays important roles in many cellular activities, the biological functions of HAD enzymes are largely unknown. Pho13 is 1 of 16 putative HAD enzymes inSaccharomyces cerevisiae. Pho13 has not been studied extensively, but previous studies have identifiedPHO13to be a deletion target for the generation of industrially attractive phenotypes, namely, efficient xylose fermentation and high tolerance to fermentation inhibitors. In order to understand the molecular mechanisms underlying the improved xylose-fermenting phenotype produced by deletion ofPHO13(pho13Δ), we investigated the response ofS. cerevisiaetopho13Δ at the transcriptomic level when cells were grown on glucose or xylose. Transcriptome sequencing analysis revealed thatpho13Δ resulted in upregulation of the pentose phosphate (PP) pathway and NADPH-producing enzymes when cells were grown on glucose or xylose. We also found that the transcriptional changes induced bypho13Δ required the transcription factor Stb5, which is activated specifically under NADPH-limiting conditions. Thus,pho13Δ resulted in the upregulation of the PP pathway and NADPH-producing enzymes as a part of an oxidative stress response mediated by activation of Stb5. Because the PP pathway is the primary pathway for xylose, its upregulation bypho13Δ might explain the improved xylose metabolism. These findings will be useful for understanding the biological function ofS. cerevisiaePho13 and the HAD superfamily enzymes and for developingS. cerevisiaestrains with industrially attractive phenotypes.

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Ito, Shoki, and Takashi Osanai. "Unconventional biochemical regulation of the oxidative pentose phosphate pathway in the model cyanobacterium Synechocystis sp. PCC 6803." Biochemical Journal 477, no. 7 (April 17, 2020): 1309–21. http://dx.doi.org/10.1042/bcj20200038.

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Metabolite production from carbon dioxide using sugar catabolism in cyanobacteria has been in the spotlight recently. Synechocystis sp. PCC 6803 (Synechocystis 6803) is the most studied cyanobacterium for metabolite production. Previous in vivo analyses revealed that the oxidative pentose phosphate (OPP) pathway is at the core of sugar catabolism in Synechocystis 6803. However, the biochemical regulation of the OPP pathway enzymes in Synechocystis 6803 remains unknown. Therefore, we characterized a key enzyme of the OPP pathway, glucose-6-phosphate dehydrogenase (G6PDH), and related enzymes from Synechocystis 6803. Synechocystis 6803 G6PDH was inhibited by citrate in the oxidative tricarboxylic acid (TCA) cycle. Citrate has not been reported as an inhibitor of G6PDH before. Similarly, 6-phosphogluconate dehydrogenase, the other enzyme from Synechocystis 6803 that catalyzes the NADPH-generating reaction in the OPP pathway, was inhibited by citrate. To understand the physiological significance of this inhibition, we characterized succinic semialdehyde dehydrogenase (SSADH) from Synechocystis 6803 (SySSADH), which catalyzes one of the NAD(P)H generating reactions in the oxidative TCA cycle. Similar to isocitrate dehydrogenase from Synechocystis 6803, SySSADH specifically catalyzed the NADPH-generating reaction and was not inhibited by citrate. The activity of SySSADH was lower than that of other bacterial SSADHs. Previous and this studies revealed that unlike the OPP pathway, the oxidative TCA cycle is a pathway with low efficiency in NADPH generation in Synechocystis 6803. It has, thus, been suggested that to avoid NADPH overproduction, the OPP pathway dehydrogenase activity is repressed when the flow of the oxidative TCA cycle increases in Synechocystis 6803.

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Igoillo-Esteve, Mariana, Dante Maugeri, Ana L. Stern, Paula Beluardi, and Juan J. Cazzulo. "The pentose phosphate pathway in Trypanosoma cruzi: a potential target for the chemotherapy of Chagas disease." Anais da Academia Brasileira de Ciências 79, no. 4 (December 2007): 649–63. http://dx.doi.org/10.1590/s0001-37652007000400007.

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Trypanosoma cruzi is highly sensitive to oxidative stress caused by reactive oxygen species. Trypanothione, the parasite's major protection against oxidative stress, is kept reduced by trypanothione reductase, using NADPH; the major source of the reduced coenzyme seems to be the pentose phosphate pathway. Its seven enzymes are present in the four major stages in the parasite's biological cycle; we have cloned and expressed them in Escherichia coli as active proteins. Glucose 6-phosphate dehydrogenase, which controls glucose flux through the pathway by its response to the NADP/NADPH ratio, is encoded by a number of genes per haploid genome, and is induced up to 46-fold by hydrogen peroxide in metacyclic trypomastigotes. The genes encoding 6-phosphogluconolactonase, 6-phosphogluconate dehydrogenase, transaldolase and transketolase are present in the CL Brener clone as a single copy per haploid genome. 6-phosphogluconate dehydrogenase is very unstable, but was stabilized introducing two salt bridges by site-directed mutagenesis. Ribose-5-phosphate isomerase belongs to Type B; genes encoding Type A enzymes, present in mammals, are absent. Ribulose-5-phosphate epimerase is encoded by two genes. The enzymes of the pathway have a major cytosolic component, although several of them have a secondary glycosomal localization, and also minor localizations in other organelles.

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Mehta, Shwetal, S. Velmurugan, and Zita Lobo. "Repression of enzymes of the pentose phosphate pathway by glucose in fission yeast." FEBS Letters 440, no. 3 (December 4, 1998): 430–33. http://dx.doi.org/10.1016/s0014-5793(98)01420-3.

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Shaw, Jeff A., Calvin A. Henard, Lin Liu, Lynne M. Dieckman, Andrés Vázquez-Torres, and Travis J. Bourret. "Salmonella entericaserovar Typhimurium has three transketolase enzymes contributing to the pentose phosphate pathway." Journal of Biological Chemistry 293, no. 29 (May 30, 2018): 11271–82. http://dx.doi.org/10.1074/jbc.ra118.003661.

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35

Alexander, M. A., V. W. Yang, and T. W. Jeffries. "Levels of pentose phosphate pathway enzymes from Candida shehatae grown in continuous culture." Applied Microbiology and Biotechnology 29, no. 2-3 (September 1988): 282–88. http://dx.doi.org/10.1007/bf00251717.

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Bettey, Mary, and W. E. Finch-Savage. "Respiratory enzyme activities during germination inBrassicaseed lots of differing vigour." Seed Science Research 6, no. 4 (December 1996): 165–74. http://dx.doi.org/10.1017/s0960258500003226.

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AbstractThe rate of oxygen consumption by cabbage seeds increased on imbibition and there was a further sharp increase on germination. This was delayed in artificially aged seeds of low vigour. The increases in oxygen consumption reflect the increased oxidation of carbohydrates via respiratory pathways. The activities of key regulatory enzymes of glycolysis and the oxidative pentose phosphate pathway were measured in aged and unaged seed lots of cabbage. Differences in the activities of glucose 6-phosphate dehydrogenase and pyrophosphate:fructose 6-phosphate 1-phosphotransferase were correlated with the rate of germination (T50) in seed lots with large differences in seed vigour induced experimentally by artificial aging. However, the activities of these enzymes could not be used to distinguish between untreated seed lots which had smaller vigour differences apparent only under stress. The enzymes are presumably not controlling and determining seed vigour, but merely reflecting actual seed performance under the current conditions.

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SHENTON, Daniel, and Chris M. GRANT. "Protein S-thiolation targets glycolysis and protein synthesis in response to oxidative stress in the yeast Saccharomyces cerevisiae." Biochemical Journal 374, no. 2 (September 1, 2003): 513–19. http://dx.doi.org/10.1042/bj20030414.

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The irreversible oxidation of cysteine residues can be prevented by protein S-thiolation, a process by which protein SH groups form mixed disulphides with low-molecular-mass thiols such as glutathione. We report here the target proteins which are modified in yeast cells in response to H2O2. In particular, a range of glycolytic and related enzymes (Tdh3, Eno2, Adh1, Tpi1, Ald6 and Fba1), as well as translation factors (Tef2, Tef5, Nip1 and Rps5) are identified. The oxidative stress conditions used to induce S-thiolation are shown to inhibit GAPDH (glyceraldehyde-3-phosphate dehydrogenase), enolase and alcohol dehydrogenase activities, whereas they have no effect on aldolase, triose phosphate isomerase or aldehyde dehydrogenase activities. The inhibition of GAPDH, enolase and alcohol dehydrogenase is readily reversible once the oxidant is removed. In addition, we show that peroxide stress has little or no effect on glucose-6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase, the enzymes that catalyse NADPH production via the pentose phosphate pathway. Thus the inhibition of glycolytic flux is proposed to result in glucose equivalents entering the pentose phosphate pathway for the generation of NADPH. Radiolabelling is used to confirm that peroxide stress results in a rapid and reversible inhibition of protein synthesis. Furthermore, we show that glycolytic enzyme activities and protein synthesis are irreversibly inhibited in a mutant that lacks glutathione, and hence cannot modify proteins by S-thiolation. In summary, protein S-thiolation appears to serve an adaptive function during exposure to an oxidative stress by reprogramming metabolism and protecting protein synthesis against irreversible oxidation.

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Pedersen, Henrik, Morten Carlsen, and Jens Nielsen. "Identification of Enzymes and Quantification of Metabolic Fluxes in the Wild Type and in a Recombinant Aspergillus oryzae Strain." Applied and Environmental Microbiology 65, no. 1 (January 1, 1999): 11–19. http://dx.doi.org/10.1128/aem.65.1.11-19.1999.

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ABSTRACT Two α-amylase-producing strains of Aspergillus oryzae, a wild-type strain and a recombinant containing additional copies of the α-amylase gene, were characterized with respect to enzyme activities, localization of enzymes to the mitochondria or cytosol, macromolecular composition, and metabolic fluxes through the central metabolism during glucose-limited chemostat cultivations. Citrate synthase and isocitrate dehydrogenase (NAD) activities were found only in the mitochondria, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase (NADP) activities were found only in the cytosol, and isocitrate dehydrogenase (NADP), glutamate oxaloacetate transaminase, malate dehydrogenase, and glutamate dehydrogenase (NAD) activities were found in both the mitochondria and the cytosol. The measured biomass components and ash could account for 95% (wt/wt) of the biomass. The protein and RNA contents increased linearly with increasing specific growth rate, but the carbohydrate and chitin contents decreased. A metabolic model consisting of 69 fluxes and 59 intracellular metabolites was used to calculate the metabolic fluxes through the central metabolism at several specific growth rates, with ammonia or nitrate as the nitrogen source. The flux through the pentose phosphate pathway increased with increasing specific growth rate. The fluxes through the pentose phosphate pathway were 15 to 26% higher for the recombinant strain than for the wild-type strain.

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Churova, M. V., N. S. Shulgina, M. Yu Krupnova, D. A. Efremov, and N. N. Nemova. "Activity of Energy and Carbohydrate Metabolism Enzymes in the Juvenile Pink Salmon Oncorhynchus gorbuscha (Walb.) during the Transition from Freshwater to a Marine Environment." Biology Bulletin 48, no. 5 (September 2021): 546–54. http://dx.doi.org/10.1134/s106235902104004x.

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Abstract Biochemical adaptations of energy metabolism and some pathways of glucose oxidation during a change in salinity of the environment in larvae and smolts of the pink salmon Oncorhynchus gorbuscha (Walb.) inhabiting the White Sea were studied. We assayed the activity of energy and carbohydrate metabolism enzymes (cytochrome c oxidase (COХ), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PDH), 1-glycerophosphate dehydrogenase (1-GPDH), and aldolase) in pink salmon larvae in a short-term aquarium experiment and in pink salmon smolts in a long-term cage experiment simulating the transition of juveniles from freshwater to a marine environment. A decrease in the activity of COX, LDH, 1‑GPDH, and aldolase already in the first hour after the transfer of larvae to seawater was shown. Smolts kept in the estuary and in the sea had low levels of activity of 1-GPDH and aldolase in comparison with individuals from the river. Most likely, in the salmon juveniles studied, there was a redistribution of carbohydrates between the reactions of aerobic and anaerobic metabolism in favor of anaerobic ATP synthesis. No changes in the enzyme activity of the pentose phosphate pathway, G-6-PDH, were found in either larvae or smolts compared with the individuals kept in freshwater. Maintenance of the required levels of anaerobic metabolism and of the pentose phosphate pathway is probably one of the mechanisms of biochemical adaptation of pink salmon to changes in salinity.

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Tsai, C. Stan, and Q. Chen. "Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe." Biochemistry and Cell Biology 76, no. 1 (February 1, 1998): 107–13. http://dx.doi.org/10.1139/o98-001.

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Hexokinase and D-glucose-6-phosphate dehydrogenase (G6PDH) from Schizosaccharomyces pombe have been purified 250-fold by an identical three-step. Both enzymes are dimeric with a molecular mass of 88 kDa for the kinase and 112 kDa for the dehydrogenase. Steady-state kinetic studies were performed on hexokinase and G6PDH, which form the glucose phosphate branch of the oxidative pentose phosphate pathway of S. pombe (fission yeast). Hexokinase promotes Mg2+-activated phosphorylation of D-glucose by the equilibrium random Bi Bi mechanism with formation of the abortive enzyme-ADP-glucose complex. ADP inhibits the kinase competitively versus ATP and noncompetitively versus D-glucose. The Mg2+activation of hexokinase is associated with an increase in the maximal velocity by its interaction with the ternary complex to facilitate the transfer of the phosphoryl group. G6PDH catalyzes NADP+-linked oxidation of D-glucose-6-phosphate by the ordered Bi Bi mechanism with NADP+as the leading reactant. High NADP+concentration inhibits the dehydrogenase by forming the dead-end ternary complex. In addition, G6PDH is also subjected to product inhibition by NADPH and noncompetitive inhibition by A(G)TP. Thus, the oxidative pentose phosphate pathway in S. pombe may be regulated via inhibition of hexokinase by ADP in conjunction with inhibition of G6PDH by NADPH and ATP.Key words: yeast hexokinase, glucose-6-phosphate dehydrogenase.

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Alfarouk, Khalid O., Samrein B. M. Ahmed, Robert L. Elliott, Amanda Benoit, Saad S. Alqahtani, Muntaser E. Ibrahim, Adil H. H. Bashir, et al. "The Pentose Phosphate Pathway Dynamics in Cancer and Its Dependency on Intracellular pH." Metabolites 10, no. 7 (July 11, 2020): 285. http://dx.doi.org/10.3390/metabo10070285.

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The Pentose Phosphate Pathway (PPP) is one of the key metabolic pathways occurring in living cells to produce energy and maintain cellular homeostasis. Cancer cells have higher cytoplasmic utilization of glucose (glycolysis), even in the presence of oxygen; this is known as the “Warburg Effect”. However, cytoplasmic glucose utilization can also occur in cancer through the PPP. This pathway contributes to cancer cells by operating in many different ways: (i) as a defense mechanism via the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) to prevent apoptosis, (ii) as a provision for the maintenance of energy by intermediate glycolysis, (iii) by increasing genomic material to the cellular pool of nucleic acid bases, (iv) by promoting survival through increasing glycolysis, and so increasing acid production, and (v) by inducing cellular proliferation by the synthesis of nucleic acid, fatty acid, and amino acid. Each step of the PPP can be upregulated in some types of cancer but not in others. An interesting aspect of this metabolic pathway is the shared regulation of the glycolytic and PPP pathways by intracellular pH (pHi). Indeed, as with glycolysis, the optimum activity of the enzymes driving the PPP occurs at an alkaline pHi, which is compatible with the cytoplasmic pH of cancer cells. Here, we outline each step of the PPP and discuss its possible correlation with cancer.

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Orita, Izumi, Takaaki Sato, Hiroya Yurimoto, Nobuo Kato, Haruyuki Atomi, Tadayuki Imanaka, and Yasuyoshi Sakai. "The Ribulose Monophosphate Pathway Substitutes for the Missing Pentose Phosphate Pathway in the Archaeon Thermococcus kodakaraensis." Journal of Bacteriology 188, no. 13 (July 1, 2006): 4698–704. http://dx.doi.org/10.1128/jb.00492-06.

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ABSTRACT The ribulose monophosphate (RuMP) pathway, involving 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexuloisomerase (PHI), is now recognized as a widespread prokaryotic pathway for formaldehyde fixation and detoxification. Interestingly, HPS and PHI homologs are also found in a variety of archaeal strains, and recent biochemical and genome analyses have raised the possibility that the reverse reaction of formaldehyde fixation, i.e., ribulose 5-phosphate (Ru5P) synthesis from fructose 6-phosphate, may function in the biosynthesis of Ru5P in some archaeal strains whose pentose phosphate pathways are imperfect. In this study, we have taken a genetic approach to address this possibility by using the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1. This strain possesses a single open reading frame (TK0475) encoding an HPS- and PHI-fused protein. The recombinant HPS-PHI-fused enzyme exhibited the expected HPS and PHI activities in both directions (formaldehyde fixing and Ru5P synthesizing). The TK0475 deletion mutant Δhps-phi-7A did not exhibit any growth in minimal medium, while growth of the mutant strain could be recovered by the addition of nucleosides to the medium. This auxotrophic phenotype together with the catalytic properties of the HPS-PHI-fused enzyme reveal that HPS and PHI are essential for the biosynthesis of Ru5P, the precursor of nucleotides, showing that the RuMP pathway is the only relevant pathway for Ru5P biosynthesis substituting for the classical pentose phosphate pathway missing in this archaeon.

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CORPAS, J. Francisco, B. Juan BARROSO, M. Luisa SANDALIO, Stefania DISTEFANO, M. José PALMA, José A. LUPIÁÑEZ, and A. Luis del RÍO. "A dehydrogenase-mediated recycling system of NADPH in plant peroxisomes." Biochemical Journal 330, no. 2 (March 1, 1998): 777–84. http://dx.doi.org/10.1042/bj3300777.

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The presence of the two NADP-dependent dehydrogenases of the pentose phosphate pathway has been investigated in plant peroxisomes from pea (Pisum sativum L.) leaves. Both enzymes, glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44), were present in the matrix of leaf peroxisomes, and their kinetic properties were studied. G6PDH and 6PGDH showed a typical Michaelis-Menten kinetic saturation curve, and had specific activities of 12.4 and 29.6 mU/mg protein, respectively. The Km values of G6PDH and 6PGDH for glucose 6-phosphate and for 6-phosphogluconate were 107.3 and 10.2 μM, respectively. Dithiothreitol did not inhibit G6PDH activity. By isoelectric focusing of peroxisomal matrices, the G6PDH activity was resolved into three isoforms with isoelectric points of 5.55, 5.30 and 4.85. The isoelectric point of peroxisomal 6PGDH was 5.10. Immunoblot analyses of peroxisomal matrix with an antibody against yeast G6PDH revealed a single cross-reactive band of 56 kDa. Post-embedment, EM immunogold labelling of G6PDH confirmed that this enzyme was localized in the peroxisomal matrices, the thylakoid membrane and matrix of chloroplasts, and the cytosol. The presence of the two oxidative enzymes of the pentose phosphate pathway in plant peroxisomes implies that these organelles have the capacity to reduce NADP+ to NADPH for its re-utilization in the peroxisomal metabolism. NADPH is particularly required for the ascorbate-glutathione cycle, which has been recently demonstrated in plant peroxisomes [Jiménez, Hernández, del Río and Sevilla (1997) Plant Physiol. 114, 275-284] and represents an important antioxidant protection system against H2O2 generated in peroxisomes.

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Enos-Berlage, Jodi L., Mark J. Langendorf, and Diana M. Downs. "Complex Metabolic Phenotypes Caused by a Mutation in yjgF, Encoding a Member of the Highly Conserved YER057c/YjgF Family of Proteins." Journal of Bacteriology 180, no. 24 (December 15, 1998): 6519–28. http://dx.doi.org/10.1128/jb.180.24.6519-6528.1998.

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ABSTRACT The oxidative pentose phosphate pathway is required for function of the alternative pyrimidine biosynthetic pathway, a pathway that allows thiamine synthesis in the absence of the PurF enzyme inSalmonella typhimurium. Mutants that no longer required function of the oxidative pentose phosphate pathway for thiamine synthesis were isolated. Further phenotypic analyses of these mutants demonstrated that they were also sensitive to the presence of serine in the medium, suggesting a partial defect in isoleucine biosynthesis. Genetic characterization showed that these pleiotropic phenotypes were caused by null mutations in yjgF, a previously uncharacterized open reading frame encoding a hypothetical 13.5-kDa protein. The YjgF protein belongs to a class of proteins of unknown function that exhibit striking conservation across a wide range of organisms, from bacteria to humans. This work represents the first detailed phenotypic characterization of yjgF mutants in any organism and provides important clues as to the function of this highly conserved class of proteins. Results also suggest a connection between function of the isoleucine biosynthetic pathway and the requirement for the pentose phosphate pathway in thiamine synthesis.

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45

Padilla, Leandro, Reinhard Krämer, Gregory Stephanopoulos, and Eduardo Agosin. "Overproduction of Trehalose: Heterologous Expression of Escherichia coli Trehalose-6-Phosphate Synthase and Trehalose-6-Phosphate Phosphatase in Corynebacterium glutamicum." Applied and Environmental Microbiology 70, no. 1 (January 2004): 370–76. http://dx.doi.org/10.1128/aem.70.1.370-376.2004.

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ABSTRACT Trehalose is a disaccharide with potential applications in the biotechnology and food industries. We propose a method for industrial production of trehalose, based on improved strains of Corynebacterium glutamicum. This paper describes the heterologous expression of Escherichia coli trehalose-synthesizing enzymes trehalose-6-phosphate synthase (OtsA) and trehalose-6-phosphate phosphatase (OtsB) in C. glutamicum, as well as its impact on the trehalose biosynthetic rate and metabolic-flux distributions, during growth in a defined culture medium. The new recombinant strain showed a five- to sixfold increase in the activity of OtsAB pathway enzymes, compared to a control strain, as well as an almost fourfold increase in the trehalose excretion rate during the exponential growth phase and a twofold increase in the final titer of trehalose. The heterologous expression described resulted in a reduced specific glucose uptake rate and Krebs cycle flux, as well as reduced pentose pathway flux, a consequence of downregulated glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. The results proved the suitability of using the heterologous expression of Ots proteins in C. glutamicum to increase the trehalose biosynthetic rate and yield and suggest critical points for further improvement of trehalose overproduction in C. glutamicum.

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46

Bertels, Laura-Katharina, Lucía Fernández Murillo, and Jürgen J. Heinisch. "The Pentose Phosphate Pathway in Yeasts–More Than a Poor Cousin of Glycolysis." Biomolecules 11, no. 5 (May 12, 2021): 725. http://dx.doi.org/10.3390/biom11050725.

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The pentose phosphate pathway (PPP) is a route that can work in parallel to glycolysis in glucose degradation in most living cells. It has a unidirectional oxidative part with glucose-6-phosphate dehydrogenase as a key enzyme generating NADPH, and a non-oxidative part involving the reversible transketolase and transaldolase reactions, which interchange PPP metabolites with glycolysis. While the oxidative branch is vital to cope with oxidative stress, the non-oxidative branch provides precursors for the synthesis of nucleic, fatty and aromatic amino acids. For glucose catabolism in the baker’s yeast Saccharomyces cerevisiae, where its components were first discovered and extensively studied, the PPP plays only a minor role. In contrast, PPP and glycolysis contribute almost equally to glucose degradation in other yeasts. We here summarize the data available for the PPP enzymes focusing on S. cerevisiae and Kluyveromyces lactis, and describe the phenotypes of gene deletions and the benefits of their overproduction and modification. Reference to other yeasts and to the importance of the PPP in their biotechnological and medical applications is briefly being included. We propose future studies on the PPP in K. lactis to be of special interest for basic science and as a host for the expression of human disease genes.

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González-Domínguez, Álvaro, Francisco Visiedo, Jesus Domínguez-Riscart, Beatriz Ruiz-Mateos, Ana Saez-Benito, Alfonso M. Lechuga-Sancho, and Rosa María Mateos. "Blunted Reducing Power Generation in Erythrocytes Contributes to Oxidative Stress in Prepubertal Obese Children with Insulin Resistance." Antioxidants 10, no. 2 (February 5, 2021): 244. http://dx.doi.org/10.3390/antiox10020244.

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Childhood obesity, and specifically its metabolic complications, are related to deficient antioxidant capacity and oxidative stress. Erythrocytes are constantly exposed to multiple sources of oxidative stress; hence, they are equipped with powerful antioxidant mechanisms requiring permanent reducing power generation and turnover. Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) are two key enzymes on the pentose phosphate pathway. Both enzymes supply reducing power by generating NADPH, which is essential for maintaining the redox balance within the cell and the activity of other antioxidant enzymes. We hypothesized that obese children with insulin resistance would exhibit blunted G6PDH and 6PGDH activities, contributing to their erythrocytes’ redox status imbalances. We studied 15 control and 24 obese prepubertal children, 12 of whom were insulin-resistant according to an oral glucose tolerance test (OGTT). We analyzed erythroid malondialdehyde (MDA) and carbonyl group levels as oxidative stress markers. NADP+/NADPH and GSH/GSSG were measured to determine redox status, and NADPH production by both G6PDH and 6PGDH was assayed spectrophotometrically to characterize pentose phosphate pathway activity. Finally, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) activities were also assessed. As expected, MDA and carbonyl groups levels were higher at baseline and along the OGTT in insulin-resistant children. Both redox indicators showed an imbalance in favor of the oxidized forms along the OGTT in the insulin-resistant obese group. Additionally, the NADPH synthesis, as well as GR activity, were decreased. H2O2 removing enzyme activities were depleted at baseline in both obese groups, although after sugar intake only metabolically healthy obese participants were able to maintain their catalase activity. No change was detected in SOD activity between groups. Our results show that obese children with insulin resistance present higher levels of oxidative damage, blunted capacity to generate reducing power, and hampered function of key NADPH-dependent antioxidant enzymes.

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Costa Rosa, L. F. B. P., R. Curi, C. Murphy, and P. Newsholme. "Effect of adrenaline and phorbol myristate acetate or bacterial lipopolysaccharide on stimulation of pathways of macrophage glucose, glutamine and O2 metabolism. Evidence for cyclic AMP-dependent protein kinase mediated inhibition of glucose-6-phosphate dehydrogenase and activation of NADP+-dependent ‘malic’ enzyme." Biochemical Journal 310, no. 2 (September 1, 1995): 709–14. http://dx.doi.org/10.1042/bj3100709.

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Adrenaline has recently been shown to stimulate both glucose metabolism and H2O2 release by macrophages but the activity of the key pentose phosphate pathway enzyme, glucose-6-phosphate dehydrogenase (which generates the NADPH crucial for the reduction of molecular oxygen), was reduced under these conditions [Costa Rosa, Safi, Cury and Curi (1992) Biochem. Pharmacol. 44, 2235-2241]. We report here that adrenaline activates another NADPH-producing enzyme, NADP(+)-dependent ‘malic’ enzyme, while also inhibiting glucose-6-phosphate dehydrogenase, via cyclic AMP-dependent protein kinase (PKA) activation. Regulation of glucose-6-phosphate dehydrogenase activity by PKA has not been reported elsewhere. The sparing of some glucose from pentose phosphate pathway consumption may be important in the provision of glycerol 3-phosphate which in the macrophage may be required for new phospholipid synthesis. Glutamine oxidation was also stimulated by adrenaline thus providing increased substrate (malate) for NADP(+)-dependent ‘malic’ enzyme and therefore shifting some of the burden of NADPH production from glucose to glutamine metabolism. We also report a novel synergistic effect of adrenaline and some bacterial products and/or gamma-interferon in stimulating secretory and metabolic pathways in macrophages which may be a part of a larger network of signals that lead to enhanced macrophage activity.

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Arthur, Patrick K., Luigi J. Alvarado, and T. Kwaku Dayie. "Expression, purification and analysis of the activity of enzymes from the pentose phosphate pathway." Protein Expression and Purification 76, no. 2 (April 2011): 229–37. http://dx.doi.org/10.1016/j.pep.2010.11.008.

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Messner, Christoph B., Paul C. Driscoll, Gabriel Piedrafita, Michael F. L. De Volder, and Markus Ralser. "Nonenzymatic gluconeogenesis-like formation of fructose 1,6-bisphosphate in ice." Proceedings of the National Academy of Sciences 114, no. 28 (June 26, 2017): 7403–7. http://dx.doi.org/10.1073/pnas.1702274114.

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The evolutionary origins of metabolism, in particular the emergence of the sugar phosphates that constitute glycolysis, the pentose phosphate pathway, and the RNA and DNA backbone, are largely unknown. In cells, a major source of glucose and the large sugar phosphates is gluconeogenesis. This ancient anabolic pathway (re-)builds carbon bonds as cleaved in glycolysis in an aldol condensation of the unstable catabolites glyceraldehyde 3-phosphate and dihydroxyacetone phosphate, forming the much more stable fructose 1,6-bisphosphate. We here report the discovery of a nonenzymatic counterpart to this reaction. The in-ice nonenzymatic aldol addition leads to the continuous accumulation of fructose 1,6-bisphosphate in a permanently frozen solution as followed over months. Moreover, the in-ice reaction is accelerated by simple amino acids, in particular glycine and lysine. Revealing that gluconeogenesis may be of nonenzymatic origin, our results shed light on how glucose anabolism could have emerged in early life forms. Furthermore, the amino acid acceleration of a key cellular anabolic reaction may indicate a link between prebiotic chemistry and the nature of the first metabolic enzymes.

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Journal articles on the topic 'Enzymes; Pentose phosphate pathway'

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