FIGURE 1.

Only a fraction of plasmin is a substrate for PGK-mediated angiostatin formation. Plasmin (20 μg) was incubated with PGK (0–80 μg) in 0.5 ml of Hepes-buffered saline for 30 min at 37 °C. Kringle-containing products were collected on lysine-Sepharose, resolved on SDS-PAGE, and silver stained. The three angiostatin fragments are indicated. The positions of molecular mass markers are shown at left.