Figure 1.

Bispecific (FcFc*) and novel product‐related parental antibody impurities (FcFc, Fc*Fc*) expressed in the production bioreactor. The theoretical expression ratio assumes equal production of either heavy chain and no thermodynamic preference for the formation of either quaternary structure. The star substitution present on the Fc* heavy chain (blue) is indicated via the circle. The Protein A binding Fc heavy chain lacking the star substitution is shown as red, and the common light chain is green.