Factor VIII and human platelet aggregation. III. Further studies on aggregation of humna platelets by neuraminidase-treated human factor VIII.
When highly purified human factor VIII is submitted to agarose gel chromatography in the presence of 0.5 M CaCl2, the procoagulant activity (low molecular weight factor VIII, LMW-F VIII) is separated from the void volume protein (Vo-VIII). Upon incubation of human factor VIII with purfied neuraminidase, a very stable platelet aggregating activity develops in the "Vo-VIII' fraction, not in the "LMS-FVIII' part. Evidence is provided that the generated aggregating activity is a property of the 'carrier protein' for LMW-F VIII. Desialylated factor VIII retains its antigenic reactivity, its procoagulant or ristocetin cofactor properties and the capacity of its subunits to dissociate and recombine. Neuraminidase-treated human factor VIII, in contrast to intact bovine factor VIII or intact human factor VIII in the presence of restocetin, does not induce aggregation of EDTA-platelet rich plasma, of congenitally afibrinogenaemic platelet rich plasma, nor of washed platelets.
D002847:Chromatography, Agarose; D005169:Factor VIII / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D009439:Neuraminidase / Q000494:pharmacology*; D010974:Platelet Aggregation; D012310:Ristocetin / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism
D012794:Sialic Acids; D012310:Ristocetin; D005169:Factor VIII; D009439:Neuraminidase