Imaging Mass Spectrometry Technology and Application on Ganglioside Study; Visualization of Age-Dependent Accumulation of C20-Ganglioside Molecular Species in the Mouse Hippocampus
Figure 2
Direct MALDI-MS and MSn allows specific detection of ganglioside molecular species.
A. Averaged mass spectra obtained from the entire hippocampal formation. In the spectra, the mass peaks corresponding to GM1, GD1, and GT1 are detected, and IMS provides distinct signals for molecular species containing C18- and C20-sphingosines. B. MSn structural analysis of ions corresponding to GM1. (a) MS2 product ion spectra show that the ions at m/z 1544 and 1572 had the same oligosaccharide structure, i.e., they contained a sialic acid moiety, but the ceramide mass peaks were observed at different m/z values. (b) MS3 product ion mass spectra of m/z 888.3 and 916.3 were obtained to determine the different structural constituents in the ceramide moieties. Because of the detection of m/z 283.0 (fatty acid-related ion) in both the spectra, the 28-u difference between m/z 1544 and m/z 1572 was attributed to the difference in the sphingosine constituent; m/z 1544 had C18-sphingosine and m/z 1572 had C20-sphingosine.