Biotherapeutic protein formulation variables influence protein integrity and can promote post-translational modifications as shown using chicken egg white lysozyme as a model system

Objectives The effect of different formulations variables on protein integrity were investigated using lysozyme as a model protein for the development of biotherapeutic protein formulations for use in the clinic. Results Buffer composition/concentration was the key variable of formulation reagents investigated in determining lysozyme stability and authenticity independent of protein concentration whilst the storage temperature and time, not surprisingly, were also key variables. Tryptic peptide mapping of the protein showed that the modifications occurred when formulated under specific conditions but not others. A model peptide system was developed that reflected the same behavior under formulation conditions as intact lysozyme. Conclusions Peptide models may mirror the stability of proteins, or regions of proteins, in the same formulations and be used to help develop a rapid screen of formulations for stabilisation of biotherapeutic proteins.