ADAMTS13 assay using mutant full-length VWF. rhuVWF-WT and mutant VWF were digested by ADAMTS13 and subject to multimer analysis. The specific susceptibility to ADAMTS13-dependent proteolysis can be assessed by comparing the loss of HMWMs of VWF and the appearance of the proteolytic subbands between wild-type and mutant VWF. (A) Compared with rhuVWF-WT (lane 1) there is a moderately increased (rhuVWF1528V, lanes 3 and 4), highly increased (rhuVWF1629E, lanes 5 and 6), or reduced (rhuVWF1628T, lanes 7 and 8) degradation of mutant VWF. Increased cleavage is less prominent in the coexpression experiments (+wt, lanes 4, 6, and 8). (B) G1506L represents a group 1 mutation and has an increased susceptibility for ADAMTS13 (lanes 3 and 4); C1272 causes almost no change in proteolytic degradation (lanes 5 and 6); and R1597W is a classical group 2 mutation and exhibits increased susceptibility for ADAMTS13-dependent proteolysis (lanes 7 and 8). w/o ADAMTS13 indicates the undigested control of rhuVWF-WT (lane 2 of panels A and B).