Plasmin digestion of fibrinogen-420 and fibrinogen-340. The first 5 lanes in each panel contain purified fibrinogen (3.4 μg/lane), either fibrinogen-420 or fibrinogen-340; the sixth contains 0.5 μg recombinant human α_EC (rα_EC), which migrates at 34 kd.14 Proteins were separated on 4% to 15% SDS-PAGE gels under nonreducing conditions. Left and middle panels: Gelcode blue stain. Right panel: Western blot analysis of fibrinogen-420 using monoclonal anti-α_EC #29-1. Positions of fibrinogen (F) and fragments X, Y, D, and E are indicated, as are those of the α_E-containing cleavage products α_ECX and its precursors (pre-α_ECX); the larger precursors can only be seen in overexposures.