Electrophoretic characterization of plasmic derivatives of fibrin. (A) SDS polyacrylamide gel electrophoresis of cross-linked fibrin (lane 1) and cross-linked fibrin after exposure to t-PA (1 μg/mL) for 1 hour (lane 2) or 4 hours (lane 3). After 2 and 4 hours, 9% and 26%, respectively, of the original fibrin clot had been solubilized. Electrophoresis of reduced protein was performed using 7% polyacrylamide gels. The locations of the polypeptide chains are indicated. (B) SDS polyacrylamide gel electrophoresis of digests of fibrin after incubation with plasmin for 45 minutes, 1 hour, 2 hours, and 3.5 hours in lanes 1 through 4, respectively. The percentage degradation of the original fibrin was 4% at 45 minutes, 5% at 1 hour, 11% at 2 hours, and 12% at 3.5 hours. The location of fragment E and the smallest cross-linked degradation products (DD, DY, and YY) are indicated. Electrophoresis of nonreduced protein was performed in 4% to 10% gradient gels.