JMSSJ On-line

JMSSJ On-line, Vol. 50 (2002) No. 2, pp. 75-77

Unexpected Fragmentation of a Novel Cationic Glycosphingolipid, Glyceroplasmalopsychosine, by Electrospray Ionization and Low Energy Multistage Mass Spectrometry		>> Full Text PDF >> References
*Keiko TADANO-ARITOMI,^a) Toshiyuki HIKITA,^{b), c)} Takeshi KASAMA,^d) Sen-itiroh HAKOMORI,^{b), c)} and Ineo ISHIZUKA^a)** ^*a)Department of Biochemistry, Teikyo University School of Medicine (Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan) ^b)Division of Biomembrane Research, Pacific Northwest Research Institute, ^c)Department of Pathobiology, University of Washington (Seattle, Washington 98195-7238, USA) ^d)Instrumental Analysis Research Center for Life Science, Tokyo Medical and Dental University (Bunkyo-ku, Tokyo 113-8510, Japan) Abbreviations: Gal, galactose; Gro, glycerol; Hex, hexose; PLPS, plasmalopsychosine

Glyceroplasmalopsychosine, Gro1(3)-O-plasmal-O-6Galβ-sphingosine, is a unique plasmal conjugate of galactosylsphingosine (psychosine) that has an O-acetal conjugate of plasmal to the hydroxyl groups of both glycerol and galactosyl residues. Electrospray ionization ion trap mass spectrometry was applied to the structural analysis of this unique compound. In the MS/MS (MS²) spectrum produced by low energy collision-induced dissociation (CID) of the [M+H]⁺ ion, elimination of glycerol was predominant. MS/MS/MS (MS³) of the [M+H-glycerol]⁺ ion yielded an outstanding anomalous ion which required the loss of a hexose in the middle of the molecule with the plasmal residue retained on the psyhchosine side. This unexpected fragmentation by MS³ could be attributed to a rearrangement of the plasmal residue to the sphingosine residue, allowing elimination of the galactose by subsequent MS³ after CID.

Key words: Glycolipids, Plasmal-containing lipids, ESIMS, Ion trap, Rearrangement

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