Characterization of murine Adamts13 cDNA. (A) Western blotting determined recombinant murine ADAMTS13. The conditioned medium containing murine (mA13) or human (hA13) ADAMTS13 or vector alone (Vector) was separated under denatured and reduced conditions on 8% SDS polyacrylamide gel electrophoresis (PAGE) and blotted with anti-V5 IgG. The controls include purified V5-tagged reference protein (Positope) (12.5, 25, and 50 ng/lane) and purified recombinant human ADAMTS13 (rAD13) as a positive control. The closed arrowhead indicates full-length murine and human ADAMTS13 proteins (∼195 kDa), whereas the open arrowhead and star indicate the intact and C-terminal fragment of the reference protein. (B) Kinetic analysis of murine (mA13, open circle) and human (hA13, closed circle) ADAMTS13 by FRETS-vWF73 at various concentrations. (C) Proteolytic cleavage of purified human VWF by conditioned medium or plasma containing murine (M) or human (H) ADAMTS13. The medium obtained from vector-transfected cells (V) or assay buffer (−) was used as controls. The proteolytic cleavage products were determined by Western blot with rabbit anti-VWF IgG that preferentially bound C-terminal portion of VWF (176K).