Bisected N-glycans
A number of complex structures with bisecting GlcNAc were present in CTRL tear fluid profiles, including two very intense ions at m/z1906.9 and 2081.1 that correspond to the agalactosyl- biantennary structure A2B and to the same structure core-fucosylated (FA2B), respectively. Since permethylated bisected species showed no characteristic fragments by MALDI MS/MS, structural characterization was achieved by comparing the fragmentation spectra with the model compound as already reported [13].