SDS-PAGE analysis of human neutrophil elastase cleavage of human factor V. Purified human F.V (600 nmol/L) was incubated at 37°C with purified HNE (2 nmol/L) in HBS, pH 7.4 with 5 mmol/L CaCl₂ and 3 μmol/L DAPA in the absence (A) or presence (B) of 50 μmol/L PCPS vesicles and simultaneous aliquots were withdrawn for prothrombinase assays and analysis by SDS-PAGE. Samples (4 μg) were withdrawn at 0, 0.5, 2, 10, 20, and 30 minutes after HNE addition corresponding to lanes 1, 2, 3, 4, 5, and 6, respectively. HNE activity was terminated by addition of SDS-PAGE sample buffer and heating at 90°C for 2 minutes. Samples were electrophoresed on 4% to 10% gradient SDS polyacrylamide gels under reducing conditions and then stained with Coomassie Blue. The migration position of molecular weight standards in (kD) is indicated on the left of each panel.