Serine protease inhibitor that acts on trypsin (Ki=190 nM) and to elastase (PubMed:32144281). Does not bind to alpha-chymotrypsin, cathepsin G, and kallikrein (PubMed:32144281). Does not show activity on all potassium channel tested (Kv1.1/KCNA1, Kv1.2/KCNA2, Kv1.3/KCNA3, Kv1.4/KCNA4, Kv1.5/KCNA5, Kv1.6/KCNA8, Shaker IR, and Kv11.1/KCNH2/ERG1). Belongs to the venom Kunitz-type family. Sea anemone type 2 potassium channel toxin subfamily.