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Urinary metabolites of L ‐threonine in type 1 diabetes determined by combined gas chromatography/chemical ionization mass spectrometry
Author(s) -
Kassel D. B.,
Martin M.,
Schall W.,
Sweeley C. C.
Publication year - 1986
Publication title -
biomedical and environmental mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0887-6134
DOI - 10.1002/bms.1200131004
Subject(s) - chemistry , electron ionization , mass spectrometry , chromatography , chemical ionization , gas chromatography , gas chromatography–mass spectrometry , threonine , protonation , amino acid , ion , ionization , biochemistry , organic chemistry , serine , enzyme
Metabolic profiling of urinary organic acids from patients with juvenile‐onset (Type 1) diabetes mellitus have revealed significantly elevated levels of 2‐hydroxybutyric acids. To test the hypothesis that these metabolites, as well as 4‐deoxyerythronic acid, are derived from L‐threonine, stable isotope‐labeled threonine was infused into an insulin‐deficient dog and the incorporation of 13 C into these metabolites was monitored by gas chromatography/mass spectrometry. Electron ionization was relatively insensitive, but positive chemical ionization with ammonia as the reactant gas gave both protonated molecules and [M+NH 4 ] + ions, which could be analysed by selected ion monitoring. The isotope‐labeled species of 2‐hydroxybutyric, 4‐deoxyerythronic and 4‐deoxythreonic acids were observed, but 13 C was not incorporated into other organic acids. Thus, it is proposed that L‐threonine is a precursor of these metabolites.