Mass spectrometry combinations for structural characterization of sulfated-steroid metabolites

Yuetian Yan, Don L. Rempel, Timothy E. Holy, Michael L. Gross

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Steroid conjugates, which often occur as metabolites, are challenging to characterize. One application is female-mouse urine, where steroid conjugates serve as important ligands for the pheromone-sensing neurons. Although the two with the highest abundance in mouse urine were previously characterized with mass spectrometry (MS) and NMR to be sulfated steroids, many more exist but remain structurally unresolved. Given that their physical and chemical properties are similar, they are likely to have a sulfated steroid ring structure. Because these compounds occur in trace amounts in mouse urine and elsewhere, their characterization by NMR will be difficult. Thus, MS methods become the primary approach for determining structure. Here, we show that a combination of MS tools is effective for determining the structures of sulfated steroids. Using 4-pregnene analogs, we explored high-resolving power MS (HR-MS) to determine chemical formulae; HD exchange MS (HDX-MS) to determine number of active, exchangeable hydrogens (e.g., OH groups); methoxyamine hydrochloride (MOX) derivatization MS, or reactive desorption electrospray ionization with hydroxylamine to determine the number of carbonyl groups; and tandem MS (MS n), high-resolution tandem MS (HRMS/MS), and GC-MS to obtain structural details of the steroid ring. From the fragmentation studies, we deduced three major fragmentation rules for this class of sulfated steroids. We also show that a combined MS approach is effective for determining structure of steroid metabolites, with important implications for targeted metabolomics in general and for the study of mouse social communication in particular. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)869-879
Number of pages11
JournalJournal of the American Society for Mass Spectrometry
Volume25
Issue number5
DOIs
StatePublished - May 2014

Keywords

  • 4-Pregnene steroids
  • DESI
  • Derivatization
  • Reactive desorption electrospray ionization (reactive DESI)
  • Steroid sulfate
  • Steroids
  • Structure determination
  • Tandem MS (MS/MS)

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