Andersson L O, Brown J E
Biochem J. 1981 Oct 15;200(1):161-7. doi: 10.1042/bj2000161.
The interaction of Factor VIII-von Willebrand Factor with phospholipid vesicles has been studied by using sucrose-density-gradient ultracentrifugation. When purified Factor VIII-von Willebrand Factor was run alone. Factor VIII activity and Factor VIIIR-Ag sedimented together to the lower half of the tube. Addition of phosphatidylserine/phosphatidylethanolamine vesicles at concentrations above 250 microgram/ml resulted in complete separation of Factor VIII activity and Factor VIIIR-Ag, the former appearing with the phospholipid on the top of the tube and the latter sedimenting as before. This separation was obtained even in the presence of proteinase inhibitors. Activation of Factor VIII-von Willebrand Factor by thrombin resulted in formation of a slow sedimenting component containing essentially all the Factor VIII activity, whereas the Factor VIIIR-Ag sedimented towards the bottom of the tube as before. The thrombin-induced Factor VIII activity was strongly bound to phospholipid vesicles as determined by density-gradient centrifugations at various Factor VIII concentrations and low concentrations of phospholipid. Based on certain assumptions a dissociation constant of 2.5 nM was calculated, a mechanism for the formation in vivo of the Factor X-activator complex is suggested.
通过蔗糖密度梯度超速离心法研究了因子VIII-血管性血友病因子与磷脂囊泡的相互作用。当单独运行纯化的因子VIII-血管性血友病因子时，因子VIII活性和因子VIIIR-Ag一起沉淀到管的下半部分。添加浓度高于250微克/毫升的磷脂酰丝氨酸/磷脂酰乙醇胺囊泡会导致因子VIII活性和因子VIIIR-Ag完全分离，前者与磷脂一起出现在管顶部，而后者像以前一样沉淀。即使在存在蛋白酶抑制剂的情况下也能实现这种分离。凝血酶对因子VIII-血管性血友病因子的激活导致形成一个缓慢沉降的组分，该组分基本上包含所有因子VIII活性，而因子VIIIR-Ag像以前一样沉淀到管底部。通过在各种因子VIII浓度和低浓度磷脂下进行密度梯度离心测定，凝血酶诱导的因子VIII活性与磷脂囊泡紧密结合。基于某些假设计算出解离常数为2.5 nM，并提出了体内因子X激活剂复合物形成的机制。
