**2.9 Deglycosylation**

Glycopeptides were lyophilized, resuspended in 10 mM AMBIC and incubated with PNGase F (5 U), for 12-16 h at 37°C. Deglycosylation was carried out also on unbound peptides, in order to release the glycans not recognized by Boronate affinity chromatography.
