Preferential cleavage: Arg-|-Xaa, Lys-|-Xaa. Causes an allergic reaction in human (PubMed:12708986, PubMed:12752596). Recombinant protein binds to IgE in 51% of the 45 patients tested allergic to B.tropicalis mites (PubMed:12708986). Native protein binds to IgE in 57% of the 44 patients tested allergic to B.tropicalis mites (PubMed:12752596). Belongs to the peptidase S1 family.