Thrombotic thrombocytopenic purpura (
TTP) is characterized by widespread platelet thrombi in arterioles and capillaries. Unusually large or multimeric
von Willebrand factor, as well as one or more platelet-agglutinating factors, have been implicated in the pathogenesis of
TTP. But, the actual mechanisms of platelet agglutination have not been satisfactorily explained. Recent studies suggested the 37-kDa platelet-agglutinating
protein (PAP) p37 to be partially responsible for the formation of platelet thrombi in patients with
TTP. We studied mobility in SDS-PAGE, the sequence of N-terminal
amino acid residues,
DNA and antigenic characteristics of PAP p37, which might be related to the pathogenesis of
TTP. PAP p37 was purified from the plasma of a 31-year-old male Korean patient with acute
TTP. The findings are as follows: (1) We compared PAP p37 with
thrombin through the use of SDS-PAGE, either with or without beta-
mercaptoethanol. PAP p37 did not appear to be cleaved between the A- and B-chains of
prethrombin 2. However,
thrombin did cleave between those of
prethrombin 2, but linked with
disulfide bridge. (2) N-terminal 21 amino acid sequence of PAP p37 was T-F-G-S-G- E-A-D-X-G-L-R-P-L-F-E-K-K-S-L-E. It appeared to be identical to that of 285-305
amino acid residues of human
prothrombin (
prethrombin 2). (3) No
prothrombin gene
DNA mutation was revealed. (4) The antigenicity of PAP p37 was similar to
thrombin, which was a result of the competitive binding against the anti-
thrombin antibody. With these results, we conclude that PAP p37 has similar characteristics to prethrombin2.