Reducing SDS-PAGE of human F.IX and F.IXa after proteolysis by plasmin.

Purified human F.IX or F.IXa (4 μM of each) was incubated with plasmin (50 nM) as described in the legend to Figure 1. Aliquots (containing approximately 4 μg of F.IX protein) of F.IX (A) or F.IXa (B) were withdrawn into reducing SDS-PAGE sample buffer after 0, 0.5, 2, 10, 20, and 30 minutes of incubation with plasmin at 37°C (lanes 1-6, respectively). F.IX and F.IXa (A, lanes 7 and 8, respectively) or F.IXa (B, lane 7) incubated as described above for 30 minutes at 37°C but in the absence of added plasmin are also shown. The migration positions of the molecular weight standards (in kd) are shown at the left of each panel.