Further characterization of ADAMTS-13 inactivation by thrombin.

摘要: Summary. Background: The multimeric size and platelettethering function of von Willebrand factor (VWF) are modulated by the plasma metalloprotease, a disintegrin metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS-13). In vitro ADAMTS-13 is susceptible to proteolytic inactivation thrombin. Objectives: this study, we aimed characterize ADAMTS13 thrombin assess its physiological significance. Methods results: By N-terminal sequencing cleavage products, mutagenesis, identified principal sites in as R257 R1176. Using library 76 mutants, highlighted functional importance exosite I on proteolysis ADAMTS-13. Proteolysis caused an 8-fold reduction affinity for VWF that contributed loss VWF-cleaving function. Intriguingly, thrombin-cleaved both bound proteolyzed short recombinant A2 domain substrate (VWF115) normally. Following activation coagulation normal plasma, endogenous ADAMTS-13, but not added appeared resistant coagulation-induced fragmentation. An estimation Km was appreciably higher than concentration This corroborated comparatively low (KD 95 nM). Conclusions: Together, our data suggest protected from rapid plasma. Whether remains case under pathological situations involving elevated/sustained generation unclear.