Analysis of the procoagulant activities of factor IX concentrates.

The Factor VIII content of Factor IX concentrates was investigated by agarose gel electrophoresis which removed the interfering effects of stabilisers and proteolytic enzyme inhibitors. Factor VIII coagulant activity (FVIII C) as measured by clotting and amidolytic methods correlated well with the distribution of FVIII coagulant antigen (FVIII CAg). The FVIIIC activity was apparently not entirely due to the presence of activated coagulation enzymes, since none of the enzymicity patterns observed with various chromogenic substrates correlated completely with the FVIII peak. However, some enzyme activity was detected in positions coincident with the margins of the FVIII peak; these activities may represent complexes of some of the FVIII with activated coagulation factors.