α₂マクログロブリンと活性第X因子の結合について

抄録

It is well known that α₂MG is an inhibitor of both thrombin and plasmin, but the interaction between α₂MG and activated factor X (Xa) has not been clarified. In the present study we investigated the inhibition of α₂MG on Xa.
α₂MG was incubated with ¹²⁵I-Xa at 37°C for 15min. By gelfiltration of the incubation mixture on Sephadex G-200, the radio-activity of ¹²⁵I was appeared with α₂MG in void volume.
The mixture of α₂MG with Xa was applied to a column of Sephadex G-200. The hydrolysed activity against S-2222 was observed in void volume, but the coagulation activity was not detected in this fraction. On the contrary, coagulation activity and hydrolysed activity against S-2222 were markedly reduced in albumin fraction.
Antithrombin III did not inhibit the hydrolysed activity of Xa after making the complex with α₂MG.
These results indicate that Xa makes a complex after binding to α₂MG, but its active site (s) is preserved.