The VWF-reducing activity of TSP-1 is contained in the E3CaG-1 fragment.

VWF (8 nM) was incubated with 0.8, 8, or 80 nM TSP-1, delNo-1, NoC-1, CP123-1, P3E123-1, or E3CaG-1. Aliquots of the reactions were analyzed for the average VWF multimer size and for the generation of new thiols in VWF. The average VWF multimer size was estimated from the ratio of the collagen-binding activity and VWF antigen level (■). Generation of new free thiols in VWF was assessed from incorporation of the biotin-linked maleimide, MPB (▪). The dotted lines represent no change in VWF multimer size (top line) or thiols in VWF (bottom line). The asterisks indicate significant difference compared to control (P < .05).