Endoglycosidases are enzymes that cleave intact glycans from glycoproteins. These enzymes are highly stable in clean preparations with no glycerol, NaCl, or other additives such as EDTA. All enzymes are tested for the absence of proteolytic or unexpected glycosidic activity.
Endoglycosidases are some of the most widely used enzymes for the analysis of glycoproteins. These enzymes release intact glycans from glycoproteins, while exoglycosidases release individual monosaccharides (i.e. sialic acid, galactose, β-N-acetylgucosamine, mannose, etc.).
PNGase F is commonly included in the group of enzymes due to its similar activity of cleaving intact N-linked glycans, though it is actually an amidase. It cleaves between the asparagine amino acid and the first β-N-acetylglucoseamine sugar (GlcNAc) of the chitobiose core of N-linked glycans. The Endo F enzymes and Endo H cleave N-linked glycans between the first and second GlcNAc, leaving a charged residue which aids in increasing solubility of the deglycosylated protein, reducing the potential for precipitation of the protein aggregates. PNGase F cleaves all N-linked glycans, while Endo H and the Endo F enzymes remove specific types of N-linked glycans.
Also included in this classification of enzymes is O-Glycosidase, which removes the Core 1 O-Linked glycan (Gal-β(1-3)GalNAc-α) from serine or threonine amino acids. Often times O-linked glycans contain additional monosaccharides linked to the galactose in both branched and linear linkages, requiring the use of exoglycosidases such as sialidase and galactosidase to remove the additional sugars.
PNGase F (Peptide N Glycosidase F) and recombinant PNGase F
PNGase F is suitable for release of all types (high-mannose, hybrid and complex) N-linked glycans from glycoproteins and glycopeptides. PNGase F will not remove oligosaccharides containing α(1-3) linked core fucose commonly found on plant glycoproteins.
Table below lists and compares the PNGase F enzyme kits offered at Ludger.