Development of a validated liquid chromatography/tandem mass spectrometry method for the distinction of thyronine and thyronamine constitutional isomers and for the identification of new deiodinase substrates

Susanne Piehl, Thomas Heberer, Gabor Balizs, Thomas S. Scanlan, Josef Köhrle

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Thyronines (THs) and thyronamines (TAMs) are two groups of endogenous iodine-containing signaling molecules whose representatives differ from each other only regarding the number and/or the position of the iodine atoms. Both groups of compounds are substrates of three deiodinase isozymes, which catalyze the sequential reductive removal of iodine from the respective precursor molecule. In this study, a novel analytical method applying liquid chromatography/tandem mass spectrometry (LC-MS/MS) was developed. This method permitted the unequivocal, simultaneous identification and quantification of all THs and TAMs in the same biological sample. Furthermore, a liquid-liquid extraction procedure permitting the concurrent isolation of all THs and TAMs from biological matrices, namely deiodinase (Dio) reaction mixtures, was established. Method validation experiments with extracted TH and TAM analytes demonstrated that the method was selective, devoid of matrix effects, sensitive, linear over a wide range of analyte concentrations and robust in terms of reproducible recoveries, process efficiencies as well as intra-assay and inter-assay stability parameters. The method was applied to study the deiodination reactions of iodinated THs catalyzed by the three deiodinase isozymes. With the HPLC protocol developed herein, sufficient chromatographic separation of all constitutional TH and TAM isomers was achieved. Accordingly, the position of each iodine atom removed from a TH substrate in a Dio-catalyzed reaction was backtracked unequivocally. While several established deiodination reactions were verified, two as yet unknown reactions, namely the phenolic ring deiodination of 3′,5′-diiodothyronine (3′,5′-T 2) by Dio2 and the tyrosyl ring deiodination of 3-monoiodothyronine (3-T1) by Dio3, were newly identified.

Original languageEnglish (US)
Pages (from-to)3286-3296
Number of pages11
JournalRapid Communications in Mass Spectrometry
Volume22
Issue number20
DOIs
StatePublished - Oct 30 2008

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry

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