The uncharged residues are required for prothrombinase inhibition by a peptide mimicking the TFPIα basic region. (A) Prothrombinase activity assays were performed as in Figure 2A using either FVaXa (filled square) or FVaIIa (open circle) and the indicated concentrations of LIKTKRKRKK (LIKT). The initial rate of thrombin generation is shown as a percentage of control (mean ± standard deviation; n ≥ 3). Lines represent best-fit inhibition curves. (B,D) Thrombin generation was measured in platelet-rich plasma as in Figure 2D, in the presence of the indicated concentrations of LIKT (B) or AAKAKRKRKK (AAKA) (D). Shown are average thrombin generation curves from experiments using at least 3 donors. (C) Prothrombinase activity assays were performed using FVaXa and the indicated concentrations of AAKA (open circle). Inhibition of FVaXa prothrombinase by LIKT (filled square) is reproduced from panel A for reference.
