Deglycosylation of asparagine-linked glycans by peptide:N-glycosidase F

Endo-beta-N-acetylglucosaminidase F (Endo F) and peptide:N-glycosidase F (PNGase F) were purified from cultures of Flavobacterium meningosepticum by ammonium sulfate precipitation followed by gel filtration on TSK HW-55(S). This system separated the two enzymes and provided PNGase F in a high state of purity, but the basis for the resolution appeared to be hydrophobic interaction and not molecular size. Studies using purified Endo F and PNGase F with defined glycopeptides demonstrated that Endo F was somewhat similar to Endo H in that it hydrolyzed many, but not all, high-mannose and hybrid oligosaccharides, as well as complex biantennary oligosaccharides. PNGase F, in contrast, hydrolyzed all classes of asparagine-linked glycans examined, provided both the alpha-amino and carboxyl groups of the asparagine residue were in peptide linkage. Deglycosylation studies with PNGase F revealed that many proteins in their native conformation were susceptible to this enzyme but that prior denaturation in sodium dodecyl sulfate greatly decreased the amount of enzyme required for complete carbohydrate removal.