Monitoring of cleavage of prothrombin by ptfV chimeric variants using SDS-PAGE analysis. (A) Prothrombin processing by ptfXa in the presence of ptfV, ptfV_hfVa1, and ptfV_hfVIIIa1 was monitored for up to 60 minutes, and reaction products at selected time points were visualized by SDS-PAGE. (B) Fraction of total for each band was determined by densitometry analysis and plotted against time to assess disappearance of prothrombin (II) and appearance Pre-2 and meizothrombin (mIIa), inferred from F1.2+light chain (F1.2-L) band and thrombin heavy chain (IIa-H), as indicated.