Anticoagulant protein that prevents the activation of factor X (F10). It acts by potently inhibiting the extrinsic tenase complex (ETC) (IC(50)=116.49 nM), a complex composed by active factor VII (F7a), tissue factor (TF) and F10. In addition, it shows weaker activities on other complexes. It weakly inhibits F10 activation by inhibiting the intrinsic tenase complex (IC(50)=4.05 uM), a complex composed by active factor IX (IXa, F9a), its cofactor factor VIII (VIIIa, F8a), and their substrate F10. It also weakly prevents prothrombin activation by inhibiting the prothrombinase complex (IC(50)=17.66 uM). It shows high kinetic constant towards F7a/TF/F10/phospholipids complex (Ki=30.62 nM) and lower kinetic constant towards F7a/TF/phospholipids complex (Ki=153.75 nM). Expressed by the venom gland. This protein does not show activity on procoagulant, anticoagulant and fibrinolytic serine proteases such as FVIIa, FXa, FIXa, FXIa, FXIIa, alpha-thrombin, kallikrein, activated protein C (APC), plasmin, urokinase, and tissue plasminogen activator (PubMed:27558950). Does not induce hemolysis (PubMed:27558950). Is classified as a P-type cytotoxin, since a proline residue stands at position 28 (Pro-31 in standard classification). Belongs to the snake three-finger toxin family. Short-chain subfamily. Orphan group XX sub-subfamily.