School of Pharmacy, University of Wisconsin–Madison, Madison WI 53705 USA.; Department of Chemistry, University of Wisconsin–Madison, Madison WI 53706 USA ; Division of Otolaryngology, Department of Surgery, School of Medicine and Public Health, University of Wisconsin–Madison, Madison WI 53792 USA ; Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin–Madison, Madison WI 53705 USA
Abstract:
Elucidating the isomeric structure of free fatty acids (FAs) in biological samples is essential to comprehend their biological functions in various physiological and pathological processes. Herein, we report a novel approach of using peracetic acid (PAA) induced epoxidation coupled with mass spectrometry (MS) for localization of the CC bond in unsaturated FAs, which enables both quantification and spatial visualization of FA isomers from biological samples. Abundant diagnostic fragment ions indicative of the CC positions were produced upon fragmentation of the FA epoxides derived from either in-solution or on-tissue PAA epoxidation of free FAs. The performance of the proposed approach was evaluated by analysis of FAs in human cell lines as well as mapping the FA isomers from cancer tissue samples with MALDI-TOF/TOF-MS. Merits of the newly developed method include high sensitivity, simplicity, high reaction efficiency, and capability of spatial characterization of FA isomers in tissue samples.A structural lipidomics approach employs peracetic acid-induced epoxidation coupled with mass spectrometry for pinpointing CC bonds in unsaturated fatty acids, enabling both quantification and imaging of FA isomers from biological samples.
