Many proteins are regulated by posttranslational modifications (PTMs) such as deamidation, phosphorylation, and glycosylation. Documented effects of PTMs include changes in enzymatic activity, interactions with other proteins, subcellular localization, and targeted degradation (1, 2). Also these physicochemical modifications may also affect receptor binding (3) or higher order structure (4) and result in clinical effects such as changes to bioactivity, immunogenicity, and bioavailability (5). The development of analytical technologies to rapidly interrogate protein structure also has direct relevance to the biopharmaceutical…