| Autor: |
Christopher MW; Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States., Ericson AC; Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States., Klug AC; Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States., Dinglasan RR; Department of Infectious Disease and Immunology, College of Veterinary Medicine, Gainesville, Florida 32608, United States., Prentice BM; Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States., Garrett TJ; Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States.; Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, College of Medicine, Gainesville, Florida 32608, United States. |
| Abstrakt: |
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. |
