Inhibition of mite protease (Df-protease) with protease inhibitors.

A protease from house dust mite(Dermatophagoides farinae) having high specificity towards a substrate of blood coagulation factor XIIa catalyzes the activation of kallikrein-kinin system in plasma (Takahashi et al., 1990). To prevent the formation of kinin by the mite-protease, inhibition of the protease with its inhibitors was tested in vitro and in vivo. Its kinetic studies revealed that Ki values are 3.9 x 10(-10) M for aprotinin, 3.0 x 10(-9) M for soybean trypsin inhibitor (Kunitz) and 2.5 x 10(-8) M for gabexate mesylate. Enhancement of blood permeability in guinea pigs caused by the protease was markedly suppressed by these inhibitors.