Gas-Phase Ion/Ion Reactions to Enable Radical-Directed Dissociation of Fatty Acid Ions: Application to Localization of Methyl Branching.

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  • Additional Information
    • Source:
      Publisher: American Chemical Society Country of Publication: United States NLM ID: 0370536 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1520-6882 (Electronic) Linking ISSN: 00032700 NLM ISO Abbreviation: Anal Chem Subsets: MEDLINE
    • Publication Information:
      Original Publication: Washington, American Chemical Society.
    • Subject Terms:
      Fatty Acids*/analysis ; Lipids*; Humans ; Mass Spectrometry ; Esters/chemistry ; Ions/chemistry ; Anions
    • Abstract:
      Methyl branching on the carbon chains of fatty acids and fatty esters is among the structural variations encountered with fatty acids and fatty esters. Branching in fatty acid/ester chains is particularly prominent in bacterial species and, for example, in vernix caseosa and sebum. The distinction of branched chains from isomeric straight-chain species and the localization of branching can be challenging to determine by mass spectrometry (MS). Condensed-phase derivatization strategies, often used in conjunction with separations, are most commonly used to address the identification and characterization of branched fatty acids. In this work, a gas-phase ion/ion strategy is presented that obviates condensed-phase derivatization and introduces a radical site into fatty acid ions to facilitate radical-directed dissociation (RDD). The gas-phase approach is also directly amenable to fatty acid anions generated via collision-induced dissociation from lipid classes that contain fatty esters. Specifically, divalent magnesium complexes bound to two terpyridine ligands that each incorporate a ((2,2,6,6-tetramethyl-1-piperidine-1-yl)oxy) (TEMPO) moiety are used to charge-invert fatty acid anions. Following the facile loss of one of the ligands and the TEMPO group of the remaining ligand, a radical site is introduced into the complex. Subsequent collision-induced dissociation (CID) of the complex exhibits preferred cleavages that localize the site(s) of branching. The approach is illustrated with iso- , anteiso- , and isoprenoid branched-chain fatty acids and an intact glycerophospholipid and is applied to a mixture of branched- and straight-chain fatty acids derived from Bacillus subtilis .
    • Grant Information:
      R15 GM121986 United States GM NIGMS NIH HHS
    • Accession Number:
      0 (Fatty Acids)
      0 (Lipids)
      0 (Esters)
      0 (Ions)
      0 (Anions)
    • Publication Date:
      Date Created: 20240214 Date Completed: 20240228 Latest Revision: 20240919
    • Publication Date:
      20240919
    • Accession Number:
      10.1021/acs.analchem.3c04510
    • Accession Number:
      38353412