Figure 4
Identification of a hybrid proteoglycan site.
(a,b) Extracted-ion current chromatograms of chondroitinase ABC- and heparinase digested perlecan samples revealed a C-terminal CS-glycopeptide (a) (m/z 1095.75; 3+) and a HS-glycopeptide (b) (m/z 1095.75; 3+), respectively, both eluting at ~39 min. (c,d) The MS2 spectra of the CS-glycopeptide (c) and HS-glycopeptide (d) provided almost identical peptide- and glycosidic fragmentation. (e,f) The oxonium-derived ion profile in the low mass range revealed higher intensities of m/z 126.06 and m/z 144.07 for the CS-glycopeptide (e) compared with the HS-glycopeptide showing higher intensities of m/z 138.05 and m/z 168.07 (f), thereby differentiating the presence of GalNAc- and GlcNAc-oxonium ions, respectively.
