Kunitz-type serine protease inhibitor (Daboia siamensis) (KPI)

Kunitz-type protease inhibitors (KPIs) from the venom of Daboia siamensis (Eastern Russell's Viper) are small, disulfide-rich proteins that play a significant role in the pathophysiology of envenomation (UniProt: P0C221). These toxins function by potently inhibiting serine proteases, including trypsin, plasmin, and various factors within the blood coagulation cascade (PubMed: 25813447). By disrupting the balance of protease activity, they contribute to symptoms such as systemic hemorrhage and coagulopathy, which are hallmarks of Russell's viper bites (NCBI: PMC4141112). In a clinical context, these proteins are the primary targets for neutralization by therapeutic antivenoms, which consist of purified antibodies or antibody fragments (PubMed: 15183871). Beyond their role as toxins, KPIs are studied for their potential as structural templates in drug design due to their high stability and specificity for protease targets (PubMed: 28601615). Effective management of envenomation relies on the rapid administration of antivenom to prevent the irreversible binding of these inhibitors to their physiological targets.

Other names

Russell's viper Kunitz-type inhibitorDrKInRusstoxinVipera russelli siamensis Kunitz-type protease inhibitorKunitz-type venom basic protease inhibitor

Therapeutic antivenoms contain specific antibodies (IgG or F(ab')2 fragments) that bind to the Kunitz-type inhibitors, sterically hindering their ability to bind and inhibit endogenous serine proteases such as plasmin or coagulation factors (PubMed: 15183871).