13C n.m.r. isotopomer and computer-simulation studies of the non-oxidative pentose phosphate pathway of human erythrocytes.
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.
Berthon
H A
HA
Department of Biochemistry, University of Sydney, NSW, Australia.
Bubb
W A
WA
Kuchel
P W
PW
D002247:Carbon Isotopes; D003198:Computer Simulation; D004912:Erythrocytes / Q000378:metabolism*; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000097:blood; D006801:Humans; D007536:Isomerism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008433:Mathematics; D008954:Models, Biological; D010427:Pentose Phosphate Pathway; D013997:Time Factors
D002247:Carbon Isotopes; D005958:Glucosephosphates; D019298:Glucose-6-Phosphate