Figure 6

GC-MS analysis of alditol acetate derivatives of the glycosyl residues of GPLs. (A) Total ion count chromatographs displaying the presence or absence of alditol acetates in extracted lipid samples from the strains indicated. (B) Mass spectra showing fragmentation pattern fingerprints demonstrating alditol acetate identity in peaks labeled 2,3,4-trimethyl- rhamnose (1), 3,4-dimethyl-rhamnose (2), and 6-deoxy-talose (3) from Ms WT + pCP0. Equivalent spectra were observed for the samples of Ms ΔgplH + pCP0-gplH (not shown). The selective ion monitoring MS analysis of the mutant strain Ms ΔgplH revealed that the strain lacks the alditol acetate derivatives. For illustration clarity, only the m/z values of selected diagnostic molecular ions are indicated in the spectra. These molecular ions arise from the fragmentation patterns of the corresponding alditol acetates as displayed next to each spectrum.