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Open AccessArticle

Quantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry

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Department of Bioinformatics and Biochemistry, BRICS, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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Luxembourg Centre for Systems Biomedicine, Université du Luxembourg, 4362 Esch-sur-Alzette, Luxembourg
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Integrated Biobank of Luxembourg, Luxembourg Institute of Health, 3555 Dudelange, Luxembourg
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Unilever R&D Vlaardingen, 3133 AT Vlaardingen, The Netherlands
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Helmholtz Zentrum für Infektionsforschung, 38124 Braunschweig, Germany
*
Author to whom correspondence should be addressed.
Metabolites 2018, 8(1), 15; https://doi.org/10.3390/metabo8010015
Received: 11 January 2018 / Revised: 7 February 2018 / Accepted: 8 February 2018 / Published: 14 February 2018
Currently, changes in metabolic fluxes following consumption of stable isotope-enriched foods are usually limited to the analysis of postprandial kinetics of glucose. Kinetic information on a larger diversity of metabolites is often lacking, mainly due to the marginal percentage of fully isotopically enriched plant material in the administered food product, and hence, an even weaker 13C enrichment in downstream plasma metabolites. Therefore, we developed an analytical workflow to determine weak 13C enrichments of diverse plasma metabolites with conventional gas chromatography-mass spectrometry (GC-MS). The limit of quantification was increased by optimizing (1) the metabolite extraction from plasma, (2) the GC-MS measurement, and (3) most importantly, the computational data processing. We applied our workflow to study the catabolic dynamics of 13C-enriched wheat bread in three human subjects. For that purpose, we collected time-resolved human plasma samples at 16 timepoints after the consumption of 13C-labeled bread and quantified 13C enrichment of 12 metabolites (glucose, lactate, alanine, glycine, serine, citrate, glutamate, glutamine, valine, isoleucine, tyrosine, and threonine). Based on isotopomer specific analysis, we were able to distinguish catabolic profiles of starch and protein hydrolysis. More generally, our study highlights that conventional GC-MS equipment is sufficient to detect isotope traces below 1% if an appropriate data processing is integrated. View Full-Text
Keywords: GC-MS; stable isotope labeling; mass isotopomer distribution (MID); plasma; nutrition GC-MS; stable isotope labeling; mass isotopomer distribution (MID); plasma; nutrition
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Krämer, L.; Jäger, C.; Trezzi, J.-P.; Jacobs, D.M.; Hiller, K. Quantification of Stable Isotope Traces Close to Natural Enrichment in Human Plasma Metabolites Using Gas Chromatography-Mass Spectrometry. Metabolites 2018, 8, 15.

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