Apoptotic activity of FDP resides in Aα17-104. (A) Nonreducing SDS-PAGE analysis of total FDP (lane 6, S) fractionated by DEAE ion-exchange chromatography. Fractions A-D (lanes 1-4) were combined (lane 5, R) to reconstitute the starting material (lane 6, S); Coomassie stain. (B) Nonreducing SDS-PAGE analysis of native (FnE, lane 1) and reduced/alkylated fibrin fragment E (lane 2); fibrinogen fragment E derived by proteolysis with hementin (Ehem; lane 3); Ehem treated with thrombin (lane 4); fibrinogen (Fgn; lane 5); fibrinogen degradation products after plasmin treatment (Fgn-DP; lane 6); Fgn-DP treated with thrombin (lane 7); recombinant E coli GST-Aα1-104 (GST1-104; lane 8) and purified recombinant Aα17-104 (lane 9). (C) Apoptotic activity of fractionated FDP on JEG3 cells, corresponding to preparations characterized in panel A. (D) Apoptotic activity of fibrin(ogen)-derived fragments characterized in panel (B). Fbg, fibrinogen; FbgE, fibrinogen fragment E; FnE, fibrin fragment E; FnE denat., FnE after reduction/alkylation. Ehem, fibrinogen fragment E derived by hementin proteolysis of fibrinogen; Ehem-thrombin, Ehem treated with thrombin to release fibrinopeptide A; GST 1-104, intact recombinant E coli GST fusion protein with Aα1-104; Aα17-104, recombinant fibrin a-chain fragment derived by thrombin-cleavage of GST 1-104, followed by removal of GST 1-16. Bars in (C) and (D) represent mean plus or minus SE from 3 independent experiments. *P < .05 by t test.