Structural elucidation of diglycosyl diacylglycerol and monoglycosyl diacylglycerol from Streptococcus pneumoniae by multiple‐stage linear ion‐trap mass spectrometry with electrospray ionization

摘要: The cell wall of the pathogenic bacterium Streptococcus pneumoniae contains glucopyranosyl diacylglycerol (GlcDAG) and galactoglucopyranosyldiacylglycerol (GalGlcDAG). specific GlcDAG consisting vaccenic acid substituent at sn-2 was recently identified as another glycolipid antigen family recognized by invariant natural killer T-cells. Here, we describe a linear ion-trap multiple-stage (MSn) mass spectrometric approach towards structural analysis GalGlcDAG GlcDAG. Structural information derived from MSn (n = 2, 3) on [M + Li]+ adduct ions desorbed electrospray ionization affords identification fatty substituents, assignment acyl groups glycerol backbone, well location double bond along chain. determination their regio-specificity were confirmed [M + NH4]+ ions. We establish structures isolated S. pneumoniae, in which major species consists 16:1- or 18:1-fatty mainly sn-2, is located ω-7 (n-7). More than one isomers found for each family. This provides simple method to achieve structure this important lipid that would be very difficult define using traditional method. Copyright © 2012 John Wiley & Sons, Ltd.