FIGURE 3.
Glycopeptide mapping and glycan profiling of the SynCAM 1 extracellular sequence. Broadband FT-ICR MS mass spectrum of four different enzymatic digestion of the purified, glycosylated SynCAM 1 extracellular sequence. 10 μg of SynCAM 1 was utilized for each digestion with CNBr (A), CNBr + trypsin (B), Lys C + trypsin (C), and protease type XIII (D). The asterisks indicate potential glycosylation sites based on exact mass measurements and GlycoMod prediction (41). The inset in B shows an enlarged region illustrating a predicted glycopeptide at m/z 1606.413 (3+) that corresponds to a modification at the Asn70 position. Note that internal calibrations were utilized to obtain mass accuracy of <5 ppm. The inset in C shows an enlarged region with a glycopeptide that corresponds to the modified Asn104 residue of SynCAM 1 at m/z 1341.616 (3+).