Figure 6

Percent inhibition of C2 activity by cattle IgGs. Inhibition assays to assess the ability of immune IgGs to inhibit C2 activity in-vitro were performed at IgG conc. of 1000, 500 and 250 μg/ml (25, 12.5, and 6.25 μg per well respectively). The amount of C2 used in the assay was 1.65 ng active enzyme per well. The C2-IgG mixtures were incubated overnight at 4°C and residual C2 activity was measured after activation with 8 mM DTT. The fluorogenic substrate used was 20 μM Z-Phe-Arg-AMC and the fluorescence recorded (excitation 360 nm and emission 460 nm). Percent inhibition of C2 activity was determined from slopes of the linear plots of residual C2 activity.