Mass Spectrometry
Online ISSN : 2186-5116
Print ISSN : 2187-137X
ISSN-L : 2186-5116
Original Article
Fragmentation of Dicarboxylic and Tricarboxylic Acids in the Krebs Cycle Using GC-EI-MS and GC-EI-MS/MS
Nobuyuki OkahashiShuichi KawanaJunko IidaHiroshi ShimizuFumio Matsuda
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Supplementary material

2019 Volume 8 Issue 1 Pages A0073


Isotope labeling measurements using mass spectrometry can provide informative insights on the metabolic systems of various organisms. The detailed identification of carbon positions included in the fragment ions of dicarboxylic and tricarboxylic acids in central carbon metabolism is needed for precise interpretation of the metabolic states. In this study, fragment ions containing the carbon backbone cleavage of dicarboxylic and tricarboxylic in the Krebs cycle were investigated by using gas chromatography (GC)-electron ionization (EI)-MS and GC-EI-MS/MS. The positions of decarboxylation in the dicarboxylic and tricarboxylic acids were successfully identified by analyses using position-specific 13C-labeled standards prepared by in vitro enzymatic reactions. For example, carboxyl groups of C1 and C6 of trimethylsilyl (TMS)- and tert-butyldimethylsilyl (TBDMS)-derivatized malic and citric acids were primarily cleaved by EI. MS/MS analyses were also performed, and fragment ions of TBDMS-citric and α-ketoglutaric acids (αKG) with the loss of two carboxyl groups in collision-induced dissociation (CID) were observed.

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© 2019 Nobuyuki Okahashi, Shuichi Kawana, Junko Iida, Hiroshi Shimizu, and Fumio Matsuda. This is an open access article distributed under the terms of Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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