Serine protease inhibitor that inhibits trypsin (Ki=50 nM). This protease exhibits a pronounced neuroprotective activity on Alzheimer's disease model. It enhances cell viability by 39.4% when neuroblastoma cells are in presence of the toxin component beta-amyloid, but has no effect when these cells are in presence of 6-OHDA. Does not show activity on the eight potassium channels 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.