Fig. 4.

Analysis of the binding of C3 and C4 to immobilized VWF-A3 domain using surface plasmon resonance. ( A ) A concentration range ( as indicated ) of C3 was analyzed across a recombinant VWF-A3 domain coupled to a biosensor surface at a flow rate of 10 μL/min. C3 bound to VWF A3 domain with a K _D of 137 nM. ( B ) Sensorgrams represent the binding of C3 (500 nM) and C4 (500 nM) to immobilized recombinant VWF-A3 domain. The C4 had a K _D  > 2.0 × 10 ³ nM, indicating a binding affinity for VWF A3 domain lower than C3 protein.