Serine protease inhibitor that inhibits trypsin (PubMed:1743283). The recombinant protein also barely blocks voltage-gated potassium channel Kv1.3/KCNA3 (3.70% inhibition at 60 nM of toxin) (PubMed:30648553). Expressed by the venom gland. Belongs to the venom Kunitz-type family.