Figure 2. Antigen-binding affinity and kinetic of the bH1 variants and Herceptin.

(A) k_on and k_off and dissociation constant (K_D) of Fabs binding to immobilized VEGF or HER2 are determined by SPR measurements (See Methods). The errors represent the standard deviations based on at least three independent experiments. bH1-81 was measured only once. Hence no error estimation is available. NB = No binding detected. ND = Not determined as the interaction was too weak to assess. The representative binding responses over time of 0.5 µM Fab bH1-44 (red), bH1-44 (LC-Y32) (green), bH1-44(LC-I29A+Y32A) (magenta) and bH1-44(HC-R50A+R58A) (gray) to immobilized VEGF₁₀₉ (B) or HER2-ECD (C).