Characterization of von Willebrand Factor Interaction with Collagens in Real Time Using Surface Plasmon Resonance

Abstract

von Willebrand factor (vWf) binding to subendothelial collagens is an initial step in thrombus formation. We have characterized the binding of vWf multimers to human pepsin-digested collagen I, III, and VI using surface plasmon resonance (BIAcore). Based on vWf subunit molecular weight (250 KDa), normal vWf multimers (nvWf) purified from human cryoprecipitate, which containing the entire range of multimers found in normal plasma, bound to human pepsin-digested collagen III with an association rate of 2.88+/-0.01 x 10(5) M(-1) s(-1), a dissociation rate of 5.85+/-0.10 x 10(-4) s(-1) and an equilibrium dissociation constant KD of 2.03+/-0.04 nM. These nvWf multimers bound to human pepsin-digested collagen I with a five fold lower binding capacity and a ten fold higher equilibrium dissociation constant. There was no detectable binding between the vWf multimers and human pepsin-digested collagen VI. The purified vWf A3 domain, vWf preparations enriched in either relatively small vWf (svWf) multimers or in unusually large vWf (ulvWf) multimers were also studied on collagen III surfaces. Our results demonstrate that the vWf dissociation rates are dependent on the vWf molecular mass and the duration of interactions. We conclude that vWf-collagen binding interactions involve multiple bond processes.