title: Identification and quantitation of unsaturated fatty acid isomers by electrospray ionization tandem mass spectrometry: a shotgun lipidomics approach.
abstract: Identification and quantification of unsaturated fatty acid (FA) isomers in a biological system are significant in the study of lipid metabolism and catabolism, membrane biophysics, and pathogenesis of diseases but are challenging in lipidomics. We developed a novel approach for identification and quantitation of unsaturated FA isomers by exploiting two facts: (1) unsaturated FA anions yield fragment ion(s) from loss of CO(2) or H(2)O from the anions upon collision-induced dissociation; and (2) the fragment ions yielded from discrete FA isomers have distinct profiles of the fragment ion intensity vs. collision conditions. These distinct profiles likely result from the differential interactions of the negative charge of the fragment ion with the electron clouds of the double bonds due to their different distances in discrete FA isomers. The novel approach was also extended to analyze the double bond isomers of FA chains present in phospholipids by multistage tandem mass spectrometry. Collectively, we developed a new approach for identification and quantification of the double bond isomers of endogenous FA species or FA chains present in intact phospholipid species. We believe that this approach should further advance the lipidomic power for identification of the biochemical mechanisms underlying metabolic diseases.
authors.affiliation: Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Kui
authors.initials: K
authors.lastname: Yang
authors.forename: Zhongdan
authors.initials: Z
authors.lastname: Zhao
authors.forename: Richard W
authors.initials: RW
authors.lastname: Gross
authors.forename: Xianlin
authors.initials: X
authors.lastname: Han
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D004041:Dietary Fats; D005231:Fatty Acids, Unsaturated / Q000032:analysis*; D007536:Isomerism; D051379:Mice; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014867:Water / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D005231:Fatty Acids, Unsaturated; D014867:Water; D002245:Carbon Dioxide