Removal of oligosaccharides from glycoproteins, termed deglycosylation, is often used in order to simplify analysis of the peptide and/or glycan portion of a glycoprotein. Detailed knowledge of the glycan structures helps to correlate them to their respective function. To do this, tools are required for highly sensitive analysis of glycan chains. Both chemical and enzymatic methods exist for removing oligosaccharides from glycoproteins. However, chemical methods such as β-elimination with mild alkali (1) or mild hydrazinolysis (2) often results in the degradation of the protein; whereas, enzymatic methods such as treating with PNGase F (NEB #P0704, NEB #P0705) or Endo H (NEB #P0702, NEB #P0703) (3) for N-glycans are much gentler and can provide complete sugar removal with no protein degradation. Unfortunately, there are no general endoglycosidases that can give complete removal of all O-linked glycans. The broadest specificity O-glycosidase (NEB #P0733, NEB #E0540) is able to cleave only core 1 and core 3 O-glycans (4). Using the O-glycosidase in combination with an appropriate mix of exoglycosidases allows the removal of large O-glycans, after the exoglycosidases have trimmed them to their core. However, for removal of intact O-glycan chains a researcher must still use chemical methods.
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