The N-glycan Glycoprotein Deglycosylation Complex (Gpd) from Capnocytophaga canimorsus Deglycosylates Human IgG
Figure 2
LC-MS analysis reveals an endo-β-N-acetylglucosaminidase activity of GpdG.
Glycosylation analysis of fetal calf serum fetuin. (A) N156 glycosylation of untreated bovine fetuin. Selected ion chromatogram for the quadruply charged tryptic peptide whose m/z is in accordance with a GlcNAc5Man3Gal3Sial3 glycosyl moiety on the LCPDCPLLAPLNDSR peptide. The inset shows the isotope pattern for the N156 glycopeptide. The blue squares represent GlcNAc, the red and green circles Man and Gal, respectively, and the orange diamonds Sial. (B) Selected ion chromatogram for the doubly charged N156 GlcNAc-modified LCPDCPLLAPLNDSR glycopeptide of fetuin that had been incubated with wild-type Cc5. The sugar moieties are designated as in (A). (C) Fragmentation spectrum of the N156- GlcNAc species with the y- and b-ions that conclusively show the GlcNAc modification of N156. (D) N156 glycosylation of bovine fetuin that had been treated with the ΔgpdG strain. Selected ion chromatogram for the quadruply charged tryptic peptide carrying the presumed GlcNAc5Man3Gal3Sial3 glycosyl moiety on the LCPDCPLLAPLNDSR peptide. The inset shows the isotope pattern for the N156 glycopeptide. The sugar moieties are designated as in (A).