scholarly journals 13C n.m.r. isotopomer and computer-simulation studies of the non-oxidative pentose phosphate pathway of human erythrocytes

1993 ◽  
Vol 296 (2) ◽  
pp. 379-387 ◽  
Author(s):  
H A Berthon ◽  
W A Bubb ◽  
P W Kuchel
Keyword(s):  
Pentose Phosphate Pathway ◽  
Time Course ◽  
Pentose Phosphate ◽  
Correlation Spectroscopy ◽  
Human Erythrocytes ◽  
Oxidative Pentose Phosphate Pathway ◽  
Double Quantum ◽  
Exchange Reactions ◽  
Cosy Spectrum ◽  
Time Course Data

13C double-quantum filtered correlation spectroscopy (DQF-COSY) provides a novel method for the detection of reactions involving carbon-bond scissions. We report the use of this technique to investigate isotopic exchange reactions of the non-oxidative pentose phosphate pathway in human erythrocytes. These exchange reactions resulted in the formation of a range of isotopic isomers (isotopomers) of glucose 6-phosphate after incubation of a mixture of universally 13C-labelled and unlabelled glucose 6-phosphate with fructose 1,6-bisphosphate and haemolysates. These isotopomers were detected in the coupling patterns of cross-peaks within the DQF-COSY spectrum of the deproteinized sample. A computer model which fully describes the reactions of the non-oxidative pentose phosphate pathway in human erythrocytes has previously been constructed and tested with 31P n.m.r. time-course data in our laboratory. This model was refined using 13C n.m.r. time-course data and extended to include the range of isotopomers which may be formed experimentally by the reactions of the non-oxidative pentose phosphate pathway. The isotopomer ratios obtained experimentally from the DQF-COSY spectrum were consistent with simulations generated by this model.

scholarly journals The pentose phosphate pathway in rabbit liver. Studies on the metabolic sequence and quantitative role of the pentose phosphate cycle by using a system in situ

1971 ◽  
Vol 123 (5) ◽  
pp. 923-943 ◽  
Author(s):  
J. F. Williams ◽  
K. G. Rienits ◽  
P. J. Schofield ◽  
M. G. Clark
Keyword(s):  
Pentose Phosphate Pathway ◽  
Time Course ◽  
Specific Radioactivity ◽  
Glucose Production ◽  
Pentose Phosphate ◽  
Rate Of Change ◽  
Exchange Reactions ◽  
High Concentration ◽  
Pentose Phosphate Cycle ◽  
Definition Of

1. The reactions of the pentose phosphate cycle were investigated by the intraportal infusion of specifically labelled [14C]glucose or [14C]ribose into the liver of the anaesthetized rabbit. The sugars were confined in the liver by haemostasis and metabolism was allowed to proceed for periods up to 5min. Metabolism was assessed by measuring the rate of change of the specific radioactivity of CO2, the carbon atoms of glucose 6-phosphate, fructose 6-phosphate and tissue glucose. 2. The quotient oxidation of [1-14C]glucose/oxidation of [6-14C]glucose as measured by the incorporation into respiratory CO2 was greater than 1.0 during most of the time-course and increased to a maximum of 3.1 but was found to decrease markedly upon application of a glucose load. 3. The estimate of the pentose phosphate cycle from C-1/C-2 ratios generally increased during the time-course, whereas the estimate of the pentose phosphate cycle from C-3/C-2 ratios varied depending on whether the ratios were measured in glucose or hexose 6-phosphates. 4. The distribution of 14C in hexose 6-phosphate after the metabolism of [1-14C]ribose showed that 65–95% of the label was in C-1 and was concluded to have been the result of a rapidly acting transketolase exchange reaction. 5. Transaldolase exchange reactions catalysed extensive transfer of 14C from [2-14C]glucose into C-5 of the hexose 6-phosphates during the entire time-course. The high concentration of label in C-4, C-5 and C-6 of the hexose 6-phosphates was not seen in tissue glucose in spite of an unchanging rate of glucose production during the time-course. 6. It is concluded that the reaction sequences catalysed by the pentose phosphate pathway enzymes do not constitute a formal metabolic cycle in intact liver, neither do they allow the definition of a fixed stoicheiometry for the dissimilation of glucose.

scholarly journals Targeting oxidative pentose phosphate pathway prevents recurrence in mutant Kras colorectal carcinomas

PLoS Biology ◽  
2019 ◽  
Vol 17 (8) ◽  
pp. e3000425 ◽  
Author(s):  
WenChao Gao ◽  
YuTing Xu ◽  
Tao Chen ◽  
ZunGuo Du ◽  
XiuJuan Liu ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Colorectal Carcinomas

scholarly journals Stoichiometric Relationship between Na+ Ions Transported and Glucose Consumed in Human Erythrocytes: Bayesian Analysis of 23Na and 13C NMR Time Course Data

2013 ◽  
Vol 104 (8) ◽  
pp. 1676-1684 ◽  
Author(s):  
Max Puckeridge ◽  
Bogdan E. Chapman ◽  
Arthur D. Conigrave ◽  
Stuart M. Grieve ◽  
Gemma A. Figtree ◽  
...  
Keyword(s):  
Bayesian Analysis ◽  
13C Nmr ◽  
Time Course ◽  
Human Erythrocytes ◽  
Na Ions ◽  
Time Course Data

Significance of the Non-Oxidative Pentose Phosphate Pathway in Aspergillus oryzae Grown on Different Carbon Sources

1991 ◽  
Vol 46 (3-4) ◽  
pp. 223-227 ◽  
Author(s):  
Maria Luisa Peleato ◽  
Teresa Muiño-Blanco ◽  
José Alvaro Cebrian Pérez ◽  
Manuel José López-Pérez
Keyword(s):  
Aspergillus Oryzae ◽  
Pentose Phosphate Pathway ◽  
Enzyme Activities ◽  
Developmental Stages ◽  
Carbon Sources ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Pentose Pathway ◽  
Hexose Phosphates

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.

scholarly journals Beneficial effects of acute inhibition of the oxidative pentose phosphate pathway in the failing heart

2014 ◽  
Vol 306 (5) ◽  
pp. H709-H717 ◽  
Author(s):  
Claudio Vimercati ◽  
Khaled Qanud ◽  
Gianfranco Mitacchione ◽  
Danuta Sosnowska ◽  
Zoltan Ungvari ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pentose Phosphate Pathway ◽  
Tissue Concentration ◽  
Glucose Consumption ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Stroke Work ◽  
Failing Heart

In vitro studies suggested that glucose metabolism through the oxidative pentose phosphate pathway (oxPPP) can paradoxically feed superoxide-generating enzymes in failing hearts. We therefore tested the hypothesis that acute inhibition of the oxPPP reduces oxidative stress and enhances function and metabolism of the failing heart, in vivo. In 10 chronically instrumented dogs, congestive heart failure (HF) was induced by high-frequency cardiac pacing. Myocardial glucose consumption was enhanced by raising arterial glycemia to levels mimicking postprandial peaks, before and after intravenous administration of the oxPPP inhibitor 6-aminonicotinamide (80 mg/kg). Myocardial energy substrate metabolism was measured with radiolabeled glucose and oleic acid, and cardiac 8-isoprostane output was used as an index of oxidative stress. A group of five chronically instrumented, normal dogs served as control. In HF, raising glycemic levels from ∼80 to ∼170 mg/dL increased cardiac isoprostane output by approximately twofold, whereas oxPPP inhibition normalized oxidative stress and enhanced cardiac oxygen consumption, glucose oxidation, and stroke work. In normal hearts glucose infusion did not induce significant changes in cardiac oxidative stress. Myocardial tissue concentration of 6P-gluconate, an intermediate metabolite of the oxPPP, was significantly reduced by ∼50% in treated versus nontreated failing hearts, supporting the inhibitory effect of 6-aminonicotinamide. Our study indicates an important contribution of the oxPPP activity to cardiac oxidative stress in HF, which is particularly pronounced during common physiological changes such as postprandial glycemic peaks.

scholarly journals Lesions in the nuo Operon, Encoding NADH Dehydrogenase Complex I, Prevent PurF-Independent Thiamine Synthesis and Reduce Flux through the Oxidative Pentose Phosphate Pathway inSalmonella enterica Serovar Typhimurium

2000 ◽  
Vol 182 (1) ◽  
pp. 228-232 ◽  
Author(s):  
Kathy Claas ◽  
Shara Weber ◽  
Diana M. Downs
Keyword(s):  
Pentose Phosphate Pathway ◽  
Nadh Dehydrogenase ◽  
Pyridine Nucleotide ◽  
Growth Conditions ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
New Class ◽  
Nucleotide Pools ◽  
Serovar Typhimurium ◽  
Cell Data

ABSTRACT In Salmonella enterica serovar Typhimurium, PurF-independent thiamine synthesis (or alternative pyrimidine biosynthesis) allows strains, under some growth conditions, to synthesize thiamine in the absence of the first step in the purine biosynthetic pathway. Mutations have been isolated in a number of loci that prevent this synthesis and thus result in an Apb−phenotype. Here we identify a new class of mutations that prevent PurF-independent thiamine synthesis and show that they are defective in the nuo genes, which encode the major, energy-generating NADH dehydrogenase of the cell. Data presented here indicated that anuo mutant has reduced flux through the oxidative pentose phosphate pathway that may contribute to, but is not sufficient to cause, the observed thiamine requirement. We suggest that reduction of the oxidative pentose phosphate pathway capacity in a nuomutant is an attempt to restore the ratio between reduced and oxidized pyridine nucleotide pools.

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