To exclude the influence of denaturing condition on interaction between VWF and antibodies, we constructed and expressed VWF-R1597W mutant and investigated whether SZ34 inhibited its proteolysis by ADAMTS13. R1597W is the most frequent mutation in von Willebrand disease type 2A and the mutation site is adjacent to Tyr1605-Met1606 bond. This mutant VWF can be cleaved by ADAMTS13 under static condition and in the absence of denaturants such as urea and guanidine [8] . The results showed that with or without SZ34 R1597W VWF multimers were equally effectively cleaved by ADAMTS13 under static conditions (Figure 4 ), which suggested that SZ34 had no effects on the proteolysis of this VWF mutant by ADAMTS13. Preliminary experiments have shown that SZ34 binds to VWF-R1597W multimers by an ELISA method and the dissociation constants (Kd) is 0.6760.11 nM.