Figure 5 rAceAP1 and rAcAP5 prolong the aPTT clotting time. Increasing amounts of purified recombinant inhibitor was added to pooled human plasma, and the aPTT clotting time measured using a microtiter plate based method. The estimated doubling time concentration for AceAP1 is 73 nM, versus 540 pM for rAcAP5.