Reactivity of rvWF with HPDP-biotin.

Biotinylation of rvWF by HPDP-biotin was performed as described in “Materials and methods.” Serial dilutions of biotinylated rvWF were added in duplicate into microtiter wells coated with anti-vWF polyclonal antibodies. On half the wells, the quantity of bound rvWF was detected by peroxidase-conjugated anti-vWF polyclonal antibodies; on the other half, the amount of biotin linked to vWF was detected by streptavidin–peroxidase. Dotted lines and empty symbols represent the native rvWF, whereas the full lines and full symbols represent the rvWF in 4 mol/L guanidine HCl. ▵, ▴, WT; ○, •, Tyr25; □, ▪, Phe95.