title: Total structure characterization of unsaturated acidic phospholipids provided by vicinal di-hydroxylation of fatty acid double bonds and negative electrospray ionization mass spectrometry.
abstract: In the present work, the unsaturated fatty acid substituents of some phosphatidic acid, phosphatidylserine, phosphatidylinositol, and phosphatidylglycerol species were converted to their 1,2-di-hydroxy derivatives by OsO(4). The subsequent electrospray ionization tandem low-energy mass spectrometry analysis of the deprotonated species allowed positional determination of the double bonds by the production of specific product-ions. The product-ions are formed by charge-remote and charge-proximate homolytic cleavages as well as charge-directed heterolytic cleavages and rearrangements. The commercial availability of pure species of the phospholipids in question was limited, and a number of species were therefore synthesized. The developed method was used to fully characterize the two isobaric phosphatidylglycerol species 16:0/16:1Delta(9) and 16:0/16:1Delta(10) extracted from the bacteria Methylococcus capsulatus. The presence of these fatty acids was supported by a gas-chromatography mass spectrometry investigation of the dimethyloxazoline derivatives of the species of the lipid extract. The present work demonstrates that a total structure characterization of acidic unsaturated phospholipids in isolate or in mixtures is accomplished by vicinal di-hydroxylation of olefinic sites and subsequent electrospray ionization mass spectrometry of the derivatized phospholipids.
authors.affiliation: University of Tromsø, Institute of Pharmacy, Tromsø, Norway. mortenm@farmasi.uit.no
authors.forename: Morten K
authors.initials: MK
authors.lastname: Moe
authors.forename: Trude
authors.initials: T
authors.lastname: Anderssen
authors.forename: Morten B
authors.initials: MB
authors.lastname: Strøm
authors.forename: Einar
authors.initials: E
authors.lastname: Jensen
mesh_terms: D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006900:Hydroxylation; D020619:Methylococcus capsulatus / Q000737:chemistry; D015394:Molecular Structure; D010712:Phosphatidic Acids / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D010716:Phosphatidylinositols / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D005231:Fatty Acids, Unsaturated; D010712:Phosphatidic Acids; D010715:Phosphatidylglycerols; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D010743:Phospholipids