Over the past decades structural characterization of macromolecules in vitro has advanced significantly. A plethora of techniques have been employed to characterize the structure of a protein macromolecule primary sequence as well as secondary and tertiary structure at atomic and sub-atomic resolution. Advanced techniques have been applied to characterize molecular dynamics of molecules and recent advances have focused on characterization of macromolecular complexes and non-covalent interactions . In the case of small molecules, the structural characterization in vitro has been extended to the in vivo realm under the auspices of biotransformation analyses. Decades of research into biotransformation of small molecule xenobiotics enriched our understanding of such processes. However, characterization of changes to protein macromolecule structure in vitro as well in vivo, i. e. biotransformation, is an emerging area of scientific inquiry . The main biotransformation pathway for traditional protein therapeutics such as monoclonal antibodies (Mabs) usually involves straightforward proteolysis . Therefore, recent work in macromolecule biotransformation has focused primarily on characterization of complex biotherapeutics such as antibody-drug conjugates (ADCs) .