Epitope mapping of mAbs within the C1 domain. (A) Peptide map of HSA-C1 protein showing 97% sequence coverage of the C1 domain. (B) Heat map of differences in deuterium exchange per residue at 0, 15, 60, and 120 seconds for the C1 domain demonstrating regions of H/D exchange protection in the presence of anti-C1 mAbs. Color scale indicates percentage of H/D exchange protection determined by the difference in percentage of deuterium exchange per residue between the antigen alone and antigen/mAb mixtures at each individual time (antigen/mAb, also referred to “Apo-mAb,” subtracted from antigen). Red indicates regions of increased H/D exchange protection and blue indicates no protection.