Determination of 13C enrichment at specific positions of plasma glucose by gas chromatographic-mass spectrometric analysis of the 1,2:5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative.
To determine 13C enrichment at specific positions of glucose, plasma samples (50-100 microliters) were deproteinized using ethyl alcohol, centrifuged, and evaporated to dryness, and the residues were derivatized with acetone/H2SO4 (100/1, v/v). After acetylation, the 1,2:5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative was analyzed by gas chromatography-mass spectrometry. The method was tested using mixtures of natural and 13C-labeled glucose molecules. Ions at m/z 113, 114, 143, 144, 287, and 288, corresponding to the C2-C4, C1-C4, and C1-C6 parts of natural or 13C-labeled glucose molecule, respectively, were selectively monitored to determine the 13C content of these fragments. This method was applied to the study of plasma glucose-labeling pattern following the infusion of [3-13C]lactic acid at tracer doses. Assuming equilibration of label through triose-phosphate isomerization in vivo, we determined the 13C enrichment of carbons 1, 2, and 3 of glucose; the values for E1/E3 and E2/E1 ratios of 8.1 and 0.77, respectively, are consistent with those obtained in studies using radioactive tracers.
Rocchiccioli
F
F
U 342 INSERM, Hôpital Saint-Vincent-de-Paul, Paris, France.
Auclair
M
M
Bougnères
P F
PF
D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism*; D002138:Calibration; D002247:Carbon Isotopes; D002675:Child, Preschool; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005943:Gluconeogenesis; D006027:Glycosides; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D012680:Sensitivity and Specificity; D014305:Triose-Phosphate Isomerase / Q000378:metabolism
D001786:Blood Glucose; D002247:Carbon Isotopes; D006027:Glycosides; D007773:Lactates; D019344:Lactic Acid; D014305:Triose-Phosphate Isomerase