FIGURE 4.

FIX cleavage by fXIa-WT in the presence of monoclonal antibodies, and in the absence of Ca²⁺ ions. Panels A–C, effects of antibodies. Shown are progress curves of fIX disappearance (●), and fIXα (○) and fIXaβ (▴) generation. FIX (100 nm) was activated by 3 nm fXIa-WT (active sites) in the presence of (A) vehicle, (B) 50 nm IgG OA16, or (C) 1000 nm IgG SB 249417. Panels D and E, importance of Ca²⁺. Shown are progress curves of fIX disappearance (●), and fIXα (○) and fIXaβ (▴) generation. FIX (1000 nm) was activated in assay buffer at room temperature by (D) fXIa-WT (5 nm active sites) in the presence of Ca²⁺, or (E) fXIa-WT (40 nm active sites) in the presence of 25 mm EDTA.