Figure 6.

Factor VIIIa degradation by APC derivatives in complex with protein S in the absence and presence of factor V. (A) The degradation of FVIIIa (10 nM) by APC-WT (O) and APC-G74S (●) in complex with protein S (110 nM) in the absence of FV was analyzed by incubating increasing concentrations of each protease with FVIIIa on PC/PS vesicles (50 μM) in TBS/Ca²⁺ in a 96-well assay plate for 3 min. The remaining cofactor activity of FVIIIa was determined by an intrinsic Tenase (1 nM FIXa and 100 nM FX for 1 min) as described in Materials and methods. (B) The same as panel A except that the reaction was carried out in the presence of human FV (10 nM).