Kunitz-type serine protease inhibitor snake venom toxin (KSPI)

Kunitz-type serine protease inhibitor (KSPI) snake venom toxins are a diverse family of small, disulfide-rich proteins (approx. 60 amino acids) characterized by the conserved Kunitz/BPTI domain (UniProt, 2024). These toxins are found in the venoms of various snake families, including Elapidae and Viperidae, where they play critical roles in prey immobilization and defense (FEBS J., 2011). Biologically, they function primarily as potent inhibitors of serine proteases involved in blood coagulation and fibrinolysis, such as trypsin, plasmin, and kallikrein, or as neurotoxic blockers of voltage-gated potassium channels (e.g., dendrotoxins) (Expasy, 2024; Harvey, 2001). In the context of disease, they contribute to the complex pathophysiology of snakebite envenomation, leading to symptoms like hemorrhage, coagulopathy, and neuromuscular paralysis (NIH, 2023). Beyond their toxic roles, KSPIs are significant in drug discovery as templates for developing anticoagulants, anti-inflammatory agents, and anti-tumor therapies due to their high specificity and stability (MDPI, 2022). Therapeutic management of KSPI-induced toxicity relies on the administration of polyvalent or monovalent antivenoms that neutralize these proteins (ResearchGate, 2026).

Other names

BPTI-like snake venom toxinSnake venom Kunitz-type inhibitorDendrotoxinTextilininKunitz-type SPI

Kunitz-type toxins act by competitively inhibiting serine proteases through binding to their active sites or by blocking voltage-gated potassium channels, thereby disrupting nerve impulse transmission. Therapeutic neutralization is achieved via antivenom antibodies that bind and sequester the toxins.