(284f) Molecular Origins of Antibody Phase Behavior

Protein aggregation is one of the most important challenges in successfully developing therapeutic antibodies, and its significance continues to grow with increasing demands for high concentration antibody formulations. Elucidating the molecular origins of antibody phase behavior is extremely difficult given the large sizes, highly variable sequences and poorly characterized structures of these proteins. To overcome these challenges, we are investigating the phase behavior of small antibody fragments which possess well-defined sequence variation on their surfaces and whose structures are known at high resolution. In this presentation, we will discuss our use of protein engineering, self-interaction measurements and phase behavior analysis to decipher the unique aggregation propensities of homologous antibody variants. Importantly, we find that the highly variable solubilities of several antibodies are not regulated through their collective amino acid sequences, but can be linked to a small set of solvent-exposed residues. We expect that our findings will guide future efforts aimed at manipulating antibody phase behavior in a rational manner.