Summary
According to some authors factor VIII procoagulant activity may be dissociable from
carrier protein (MW~ 2 × 106) by agarose gel filtration, e.g. at high ionic strength. We were able to reproduce
this phenomenon. However, addition of protease inhibitor (Trasylol) prevented the
appearance of low molecular weight peak of factor VIII procoagulant activity both
at high ionic strength and elevated temperature (37°C). We conclude from our results
that procoagulant activity and carrier protein (von Willebrand factor, factor VIII
antigen) are closely associated functional sites of native factor VIII macro molecule.
Consequently, proteolytic degradation should be avoided in functional and structural
studies on factor VIII and especially in preparing factor VIII concentrate for therapeutic
use.