Correlation between the effect of HNE and the cofactor activities of F.V and F.Va and the appearance/dissappearance of specific protein fragments. The SDS gels for F.V (A) or F.Va (B) from Figs 2A and 3A, respectively, were scanned using a Hewlett Packard ScanJet 3C and the density of each fragment calculated as described in Materials and Methods. The data from the corresponding prothrombinase assays (F.V, Fig 1A; F.Va, Fig 1B) is plotted against the densitometry data to relate fragment appearance/disappearance after HNE treatment to changes in cofactor activity. In (A), the cofactor activity (left axis) of F.V (•) is plotted against the density (right axis) of fragments of apparent molecular mass of 99/97 kD (▪); 89/87 kD (▴); and 76/74 kD (▾). In (B), the cofactor activity (left axis) of F.Va (•) is plotted against the density (right axis) of the 96-kD heavy chain (▪) and the 74/72 kD light chain (▴).