Daboia russelii siamensis Kunitz-type serine protease inhibitor (DrS-Kunitz)

Daboia russelii siamensis Kunitz-type serine protease inhibitor toxins are a group of small proteins (approximately 6-7 kDa) found in the venom of the Eastern Russell's Viper (Daboia siamensis). These toxins possess a characteristic Kunitz fold stabilized by three conserved disulfide bonds, which allows them to function as potent competitive inhibitors of various serine proteases, such as trypsin and chymotrypsin (UniProt P00991). In the context of human envenomation, these inhibitors interfere with the delicate balance of the coagulation and fibrinolytic cascades, contributing to the severe systemic symptoms of Russell's viper bites, including viper-induced consumptive coagulopathy (VICC) and spontaneous hemorrhage (Journal of Proteomics, 2014). While they are primarily viewed as toxic agents, they are the specific targets of therapeutic antivenoms, which utilize polyclonal antibodies to sequester and neutralize the toxins in the bloodstream. Beyond their role in pathology, these Kunitz-type inhibitors are valuable in biochemical research and drug discovery as scaffolds for developing highly specific protease inhibitors for treating conditions like thrombosis or excessive inflammation (Toxins, 2018).

Other names

Daboia siamensis Kunitz-type inhibitorEastern Russell's viper Kunitz-type protease inhibitorVipera russelli protease inhibitorKunitz-type venom basic protease inhibitorDrKIn

Neutralization by antivenom antibodies which bind to the toxin's active site or surface epitopes, sterically hindering its interaction with host serine proteases and preventing the inhibition of endogenous coagulation factors.