Kinetic inhibition of plasma ADAMTS13 by three antispacer antibodies at different temperatures and pHs. Titration of plasma ADAMTS13 activity with FRETS-VWF73 in the presence of various concentrations of scFv4-20, scFv3-1, and scFv4-16 under different conditions: (1) temperature of 37°C and pH of 6.0 for scFv4-20 (A), scFv3-1 (B), and scFv4-16 (C); (2) temperature of 25°C and pH of 6.31 for scFv4-20 (D), scFv3-1 (E), and scFv4-16 (F) (n ≥ 3 for all titrations). The data in the plots are shown as mean ± SEM.