Binding of denatured VWF to ADAMTS13 and C-terminal truncated variants. Purified VWF pretreated for 2 hours with 1.5 M guanidine-HCl at 37°C was diluted (1:10) with HBS-T buffer with (not shown) or without EDTA into various concentrations (0 to 125 μg/mL or 0 to 500 nM). The diluted VWF was then injected at 20 μL/min for 3 minutes over the CM5 chips covalently coupled by FL-A13 (A), delCUB (B), and MDTCS (C). After the equilibrium was established, the HBS-T buffer without VWF was flowed over the surface to allow the dissociation phase to be recorded. The equilibrium constant, K_D, was determined similarly as described for Figure 3. The entries in panel D represent the means (± SD) of 6 repeats.