Heterogeneity of plasma von Willebrand factor multimers resulting from proteolysis of the constituent subunit.

Abstract

In this report we demonstrate that proteolytic cleavage of the constituent subunit is one of the causes determining the heterogeneous size distribution of plasma von Willebrand factor (vWf) multimers. As shown by two-dimensional nonreduced/ reduced agarose/polyacrylamide gel electrophoresis, the structure of circulating vWf molecules may deviate from that represented by assemblage of a variable number of identical subunits. Indeed, even though the largest multimers in normal plasma appear to be composed predominantly of intact 225-kD subunits, those of intermediate and smaller size contain also 189-, 176-, and 140-kD proteolytic fragments. Different subunit composition patterns are repeated regularly in multimers ofincreasing molecular mass, yielding series of bands with similar structure. One of these series consists of molecules without evidence of proteolytic fragmentation, and its smallest member appears to be a dimer of 225-kD subunits. Type IIA von Willebrand disease, characterized by absence of the largest multimers, displays a pattern wherein the fragments of 176 and 140 kD are relatively increased, that of 189 kD is markedly decreased or absent, but the composition of individual multimers is otherwise similar to that of species seen also in normal plasma. In contrast to those in the circulation, all normal platelet vWf multimers contain only intact subunit. These results suggest that proteolytic cleavage of plasma vWf subunits occurs after release from cellular sites, whereas platelet vWf stored in a-granules is protected from proteolysis. These findings provide information that may be relevant for understanding the normal processing of vWf multimers and for elucidating the pathogenesis of some of the congenital and acquired structural abnormalities of this molecule. (J. Clin. Invest. 1991.

Native multimer analysis of plasma and platelet von Willebrand factor compared to denaturing separation: Implication for the interpretation of satellite bands

“…The absence of the characteristic triplet subband structure in platelet vWF shown by SDS multimer analysis (Dent et al 1991;Ott et al 2010), could not be confirmed properly with the use of 2-D blue native/SDS-agarose electrophoresis. The second dimension of normal platelet vWF even showed a triplet structure (Hohenstein et al 2011;figure 4).…”

von Willebrand factor cleaving protease (ADAMTS13) is deficient in recurrent and familial thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

“…8 However, UL multimers do not normally circulate because they are cleaved into smaller multimers soon after their secretion. [10][11][12][13] In patients with TTP or HUS, in contrast to healthy subjects, UL multimers are sometimes detected in plasma. 14,15 The relationship between UL VWF multimers and thrombotic microangiopathies remained elusive until the recent demonstration of the presence in human plasma of a metalloprotease (ADAMTS13) [16][17][18] that cleaves VWF physiologically at the peptide bond between amino acid residues 842Thr and 843Met in the A2 domain of the subunit.…”

Structural analysis of recombinant von Willebrand factor produced at industrial scale fermentation of transformed CHO cells co‐expressing recombinant furin

“…(terminology according to [15]) in the first dimension. Second dimension electrophoresis showed that this protein band contained exclusively mature vWF subunits.…”