Effects of succinylation and dodecyl succinylation on bovine factor VIII/von willebrand factor complex

Blocking the ϵ-amino·groups of the lysine residues in the bovine VIII/vWf complex by succinylation and dodecyl succinylation resulted in the total loss of procoagulant activity. In contrast, the platelet aggregating activity was totally lost after succinylation, but only partially lost after dodecyl succinylation. The VIII R-Ag of modified complex remained active as shown by rocket immunoelectrophoresis and crossed immunoelectrophoresis. The net gain of negative charges by these two reactions resulted in an increase in mobility to the anode of their products upon electrophoresis. In the presence of SDS, no change in mobility was observed, indicating that no dissociation of subunits had occurred. These findings suggest that lysine residues are involved in the binding and/or active sites of the VIII/vWf complex and the hydrophobic 16-carbon chain introduced to this complex by dodecyl succinylation might play a stabilizing role in the platelet-von Willebrand factor interaction.