FIGURE 7.

Effect of the BR peptide on FV-810 thrombin cleavage site variants. A, schematic of the partial cleavage products generated by incubating FV-810 containing the R709Q and/or R1545Q mutation with thrombin. B, reactions containing 600 nm FV-810, FV-810^R709Q, FV-810^R1545Q, FV-810^QQ, or rFVa were incubated for 15 min at 37 °C with buffer or 10 nm thrombin and then quenched with 20 nm hirudin. Samples were resolved by 4–12% gradient SDS-PAGE under reducing conditions and stained with Coomassie Brilliant Blue. C and D, specific clotting activities of FV-810 variants after incubation with buffer (C) or thrombin (D). FV-deficient plasma was supplemented with the quenched reaction products at 0.25 nm, and specific activity was measured in the absence (white bars) or presence (gray bars) of 5 μm BR peptide.