Fibrin gel zymograms of proteases in QPD platelets.

Samples of QPD (Q₁ and Q₂ indicate patients from families 1 and 2, respectively) and control (C) platelet lysates (lys; A, 12.5 μL; B, 2 μL) and ADP releasates (ADP rel; A, 50 μL; B, 2 μL) were analyzed on fibrin substrate gels after 9% (A) or 5% to 15% (B) nonreduced SDS-PAGE. (A) Analyses using gels without added plasminogen indicated QPD platelets contained 50-kd (major band) and 100-kd (minor component) secretable, fibrinolytic proteases (arrows) that were not evident in the same amount of control samples. (B) Comparative analyses, using substrate gels with (+) or without (−) added plasminogen, indicated the 100- and 50-kd QPD platelet proteases had properties of plasminogen activators. A 33-kd plasminogen activator was also detected in QPD (but not in control) platelets and releasates (M_r based on 5%-15% nonreduced SDS-PAGE).