One of the most common posttranslational modifications of eukaryotic proteins is glycosylation. Glycosylation of proteins can affect many biological activities. For therapeutic glycoproteins, it can modify biological activity, targeting, trafficking, serum half life, clearance, and recognition by receptors (1, 2). For such reasons, biomanufacturers must monitor and characterize the glycosylation patterns of their recombinant therapeutic proteins (3, 4). Therapeutic proteins have two main types of glycosylation: N-linked glycans and O-linked glycans (5). Attachment of an N-glycan starts in the endoplasmic…