A common large-scale strategy utilizes a glycopeptide or glycoprotein enrichment step followed by glycan removal. Glycopeptides are usually enriched using lectins, hydrophilic interaction LC, hydrazide or graphite. The method of choice will determine the type of glycopeptides that will ultimately be enriched.90,91 After enrichment, PNGase-F is used to enzymatically remove the glycan moiety from asparagine residues, serving two purposes: Firstly, the core peptide can be analysed without interference from sugars during MS/MS and secondly, PNGase-F via a deamidation reaction converts the asparagine to aspartic acid. This conversion is characterized by a 0.984 Da mass shift that can be detected using MS. Moreover, if the reaction is performed in the presence of H218O, it instead leads to a 2.99 Da mass shift, indicative for the presence of glycosylation at that position. Using this methodology in rat hearts, Parker et al.58 identified 1556 N-linked glycosites from 972 protein groups. This study provided information on the changes in glycosylation following ischemia and reperfusion. Enzymatic deglycosylation allows for the separate analysis of the core protein and glycan,92 but the link between the glycans and peptides is lost.