島津評論 77〔1・2〕 79～84 (2020.9)
Chemical ionization (CI) is an important technique for gas chromatography mass spectrometry to investigate molecular weights. A new chemical ionization approach, solvent mediated chemical ionization (SMCI), enables the generation of molecular ions for molecular weight determination as efficiently as conventional CI. In addition, SMCI generates specific information about unsaturated fatty acids when implemented on a triple quadrupole gas chromatography mass spectrometer (GC-MS/MS), identifying double bond positions in unsaturated fatty acids. Fatty acid desaturase genes (FADS1, 2) insert double bonds in fatty acids. We confirm and extended that FADS2 especially catalyzes Δ4-, Δ6- and Δ8- desaturations in fatty acids using SMCI and GC-MS/MS. This technique can be applied to branched chain fatty acids which are present in human skin. FADS2 is also expressed in human skin and performs the same function, the desaturations of fatty acids. Here, SMCI and GC-MS/MS discovered that FADS2 desaturates branched chain fatty acids at the Δ6 position.
Keywords : Fatty acid methyl esters, Branched chain fatty acids, Fatty acid desaturase 2, Chemical ionization, Gas chromatography mass spectrometry
1Dell Pediatric Research Institute, Dell Medical School, The University of Texas at Austin, Texas, USA
2Global Application Development Center, Analytical & Measuring Instruments Division, Shimadzu Corporation, Kyoto, Japan