Effect of HRPII on the heparin-induced prolongation of plasma clot time. aPTT reagent (100 μL) was premixed with citrated pooled normal plasma (100 μL) before adding zinc acetate (10 μL, 20 μM final) with or without varied concentrations of HRPII (20μL) with or without varied concentrations of heparin (20 μL). The mixture was allowed to incubate at 37°C for 3 minutes, after which CaCl₂ (50 μL, 10mM final, prewarmed to 37°C) was added and the clot time recorded as described in “Clotting assay.” (A) Effect of increasing amounts of heparin on aPTT in the presence and absence of 700nM HRPII. (B) Effect of increasing amounts of HRPII on aPTT in the presence and absence of 0.1 U/mL heparin. Data points and error bars represent mean ± SE for 2 independent experiments performed in duplicate.