Rate of Asparagine Deamidation in a Monoclonal Antibody Correlating with Hydrogen Exchange Rate at Adjacent Downstream Residues.

Antibodies are an important class of drugs, comprising more than half of all new FDA approvals. Therapeutic antibodies must be chemically stable both in storage and in vivo, following administration to patients. Deamidation is a major degradation pathway for all natural and therapeutic proteins circulating in blood. Here, the linkage between deamidation propensity and structural dynamics is investigated by examining two antibodies with differing specificities. While both antibodies share a canonical asparagine-glycine (NG) motif in a structural loop, this is prone to deamidation in one of the antibodies but not the other. We found that the hydrogen-exchange rate at the adjacent two amides, often the autocatalytic nucleophiles in deamidation, correlated with the rate of degradation. This previously unreported observation was confirmed upon mutation to stabilize the deamidation lability via a generally applicable orthogonal engineering strategy presented here. We anticipate that the structural insight into chemical degradation in full-length monoclonal antibodies and the high-resolution hydrogen-exchange methodology used will have broad application across biochemical study and drug discovery and development.