Recombinant fXI species (30 nM) were incubated without (□,○,∆) or with (■,●,▲) (A) 5 μg/ml DNA or (B) 1 μg/ml RNA, and with 2.5 nM thrombin (left) or 2.5 nM fXIIa (right). Symbols: fXI-WT (□,■), fXI-ABS1 (○,●), or fXI-ABS2 (∆,▲). (C) FXI-ABS2 (30 nM) was incubated with 5 μg/ml DNA and 2.5 nM thrombin (left) or 2.5 nM fXIIa (right) without (○) or with (●) 30 nM HK. (D) 60 nM PK-WT (left) or PK-ABS2 (right) were incubated with 50 pM fXIIa in the presence of 5 μg/ml DNA without (○) or with (●) 60 nM HK. For all reactions, at indicated time points, aliquots were tested for fXIa or kallikrein activity by chromogenic assay. Error bars are +/−one SD.