MOESM4 of User-friendly extraction and multistage tandem mass spectrometry based analysis of lipid-linked oligosaccharides in microalgae

Additional file 4. Multistage tandem mass spectrometry analyses of the structure of the LLO-released oligosaccharide isolated from P. tricornutum. ESI-MSn spectra with n = 3 (panels A, C and E) and n = 4 (panel B and D) of permethylated Hex11HexNAc2 derivative (m/z 1413.5 corresponding to [M + 2Na]2+ precursor ion) isolated from P. tricornutum. On each panel, the ion selected for the fragmentation analysis is shown with a diamond and its fragmentation pattern is proposed according to Prien et al. [40]. Black square: N-acetylglucosamine; grey circle: mannose, black circle: glucose. The fragment ions are labelled according to the nomenclature of Domon and Costello [41]. Note that loss of 190 u correspond to the elimination of a hexose residue which was linked with three other residues in the oligosaccharide (for example, a 1,3,6-linked hexose residue). Therefore, the successive losses of two 218 u (m/z 1247.6 → m/z 1029.5 → m/z 811.5) indicate a di-antenna ion m/z 1247.6 while the loss of 190 u followed by successive losses of 204 u (m/z 1247.6 → m/z 1057.5 → m/z 853.5 → m/z 649.4 → m/z 445.3) indicate a linear ion m/z 1247.6.