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Divergent Metabolic Fates of Aromatic Amino Acid-Derived Isomers: Insights from Ex Vivo Metabolomics and HDX-HRMS/MS-Based Resolution of Tautomers.
- Source :
-
Analytical chemistry [Anal Chem] 2024 Oct 22; Vol. 96 (42), pp. 16917-16925. Date of Electronic Publication: 2024 Oct 07. - Publication Year :
- 2024
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Abstract
- Tautomers are one of the many types of isomers, and differences in tautomeric structures confer altered chemical and biological properties. Using ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) ex vivo metabolomics, we investigate, in whole blood, the divergent metabolism of enol and keto forms of indole-3-pyruvate (IPyA), a tautomeric product of aromatic amino acid metabolism. Two new compounds resulting from IPyA metabolism were discovered, 3-(1 H -indol-3-yl)-2,3-dioxopropanoic acid or "indole-3-oxopyruvic acid" and glutathionyl-indole pyruvate (GSHIPyA), which were characterized via ultraviolet photodissociation (UVPD) and higher-energy collisional dissociation (HCD). Computational calculations support the hypothesis that GSHIPyA forms specifically through the enol form of IPyA. GSHIPyA is also hypothesized to be tautomeric, and a hydrogen-deuterium exchange-high-resolution tandem mass spectrometry (HDX-HRMS/MS) approach is developed to prove the presence of an enol and keto tautomer. HDX of GSHIPyA labels the keto form with an additional deuterium, relative to the enol form. HRMS/MS of the labeled isomers is employed to leverage the relationship of resolving power scaling inversely with the square root of m / z , for Orbitrap mass analyzers. HRMS/MS yields a smaller-molecular-weight deuterated tautomeric product ion, reducing the analyte ion m / z and thus lowering the resolving power necessary to separate the deuterated keto tautomer product ion from the [13]C product ion.
Details
- Language :
- English
- ISSN :
- 1520-6882
- Volume :
- 96
- Issue :
- 42
- Database :
- MEDLINE
- Journal :
- Analytical chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 39374072
- Full Text :
- https://doi.org/10.1021/acs.analchem.4c03862