A) Wild type strain W83 and its mutants lacking gingipains grown as described in Fig. 1 were incubated with (50 µg/ml) C4BP-FITC for 30 minutes at RT, washed and analyzed by flow cytometry. Binding of C4BP to W83 in each experiment was set as 1. Statistical significance of differences between tested stains was estimated with Student’s t-test, *** p<0.001. B) Purified HRgpA, RgpB and Kgp were immobilized on microtiter plates and incubated with indicated concentrations of C4BP, binding of which was detected with specific monoclonal antibodies. In each experiment, the binding of highest concentration of C4BP to HRgpA was set as 1 and all values were normalized C) C4BP (15 µg/ml) was incubated with HRgpA immobilized on microtiter plates in the presence of indicated concentrations of fibrinogen and prothrombin and the binding of C4BP was detected with a monoclonal antibody. Binding at every condition in A–C was analyzed three times in doublets. Shown are mean values +/− SD.