Binding interactions of small molecule inhibitors to β-FXIIa. (A) Close-up view of the inhibitor binding area in the benzamidine complex (gray ribbon). The benzamidine molecule (green sticks) bound to the S1 site, the residues defining the interaction with the inhibitors, the residues of the catalytic triad, and the bound phosphate ions (yellow) are shown as sticks. The electron density maps (blue) around the bound inhibitor and the ion are countered at 1σ. (B) The compound 1–β-FXIIa complex. The same view as in panel A.